Prostate-specific membrane antigen (PSMA)-PET/CT has shown considerable promise in the evaluation of prostate cancer bone metastases; however, data utilizing a histopathologic reference standard in this setting are limited. We therefore sought to evaluate the diagnostic performance of PSMA-PET/CT using a consistent histopathologic gold standard in the form of bone biopsy.

In this single-center, retrospective study, we identified 80 patients with prostate cancer who underwent CT-guided bone biopsy of a tracer-avid osseous lesion on PSMA-PET/CT performed with 18F-piflufolastat. Concordance between PET/CT and histopathology and the positive predictive value of PSMA-PET/CT were determined. Factors predictive of positive biopsies were also evaluated.

PSMA-PET/CT and bone biopsy results were concordant in 55/80 patients (69%), and the positive predictive value of PSMA-PET/CT for osseous metastasis of prostate cancer was 66% (53/80). Positive predictive values for spine, pelvis, and rib biopsies were 82% (23/28), 72% (18/25), and 26% (5/19), respectively. Peak SUV and its ratio to liver mean SUV were significantly higher in biopsy-positive lesions compared to biopsy-negative lesions. A threshold peak SUV to liver mean SUV ratio of 1.7 had a sensitivity of 61% and a specificity of 92% for a histopathologic diagnosis of metastatic prostate cancer.

PSMA-PET/CT has a moderately high histopathologic concordance and positive predictive value for the diagnosis of osseous metastatic disease in prostate cancer. Peak SUV is useful for distinguishing biopsy-positive from biopsy-negative lesions. In keeping with prior investigations, a majority of biopsied rib lesions were negative for metastatic prostate cancer.

Recently developed dynamic whole-body PET/CT (D-WB PET/CT) protocols allow for measurements of potentially more precise metabolic parameters than the commonly used semiquantitative SUV. Most notable is the metabolic rate of FDG uptake (MRFDG), which reflects quantitative glucose uptake into tissues and organs. However, data on the reproducibility of MRFDG measurements are scarce, particularly in patients with perturbed glucose homeostasis such as type 2 diabetes. We therefore aimed to evaluate the test-retest repeatability of both MRFDG and SUV in these patients.

Fifteen participants (mean age 71 ± 7 years; 2 females) with type 2 diabetes underwent a short 20-minute [18F]FDG D-WB PET/CT after 6 h fasting on two consecutive days. Both SUV and MRFDG images were reconstructed from D-WB PET/CT data obtained 60-80 min post-injection of [18F]FDG. MRFDG and SUV data were measured in organs and tissues, and repeatability was assessed with Bland-Altman analysis, intraclass correlation coefficients (ICC), repeatability coefficients (RPC) and coefficients of variation (wCV). There was high repeatability of both SUVmean and MRFDG-mean in all measured organs (ICC range: 0.65-0.95 for SUVmean and 0.66-0.94 for MRFDG-mean). SUVmean generally demonstrated higher reliability (ICC) and lower variability (%RPC and %wCV) when compared to MRFDG-mean. However, MRFDG test-retest variation was < 19% in most analysed tissues, demonstrating that MRFDG may be used as a precise marker of treatment response.

This study demonstrates that MRFDG calculated from D-WB PET/CT exhibit high repeatability, comparable to SUVs across most organs in patients with type 2 diabetes.

The intricateness of tumor immune microenvironment types (TIMTs) complicates identifying responders to immune checkpoint inhibitors (ICIs). Our purpose was to explore the metabolic characteristics of TIMTs in breast cancer using 18F-fluorodeoxyglucose (FDG) PET/CT and to establish radiomics-based predictive models for TIMTs.

Consecutive 207 breast cancer patients (211 primary lesions), who underwent 18F-FDG PET/CT examination from Sep 2022 to Aug 2024 in our hospital, were retrospectively reviewed. The programmed death-ligand 1 (PD-L1) and tumor-infiltrating lymphocytes (TILs) were evaluated for TIMTs: TMIT-I (PD-L1-, TILs-), TMIT-II (PD-L1+, TILs+), TMIT-III (PD-L1-, TILs+), and TMIT-IV (PD-L1+, TILs-). The relationship between metabolic parameters (such as maximum standardized uptake value (SUVmax) and tumor-to-liver SUV ratio (TLR)) and TIMTs was analyzed. Then composite predictive models based on radiomics were further developed.

TIMT-II represented the highest proportion in HER2+ (14/22, 64%) and triple-negative (17/27, 63%) breast cancer. Most metabolic parameters (such as SUVmax and TLR) exhibited significant differences in TIMT-II vs. -I or TIMT-II vs. -III (P < 0.05). TLR (P = 0.03; OR: 1.1) and Nottingham grade (P = 0.006; OR: 3.1) were independent impact factors of TIMT-II. We further developed a composite model that integrated radiomics, metabolic parameter, and clinicopathological data, which demonstrated promising predictive efficacy for TIMT-II (AUC testing set = 0.86).

Metabolic differences existed among different TIMTs, with TIMT-II exhibiting markedly elevated metabolic characteristics. The composite model based on radiomics demonstrated high predictive efficacy for TIMT-II and has the potential to screen ICIs responders.

To perform a systematic review and meta-analysis to assess the relationship between intraprostatic maximum standardised uptake value (SUVmax) of the dominant prostatic lesion as measured on preoperative prostate-specific membrane antigen (PSMA) positron emission tomography (PET) with radical prostatectomy International Society of Urological Pathology (ISUP) Grade Group, pathological tumour (pT) staging, and biochemical recurrence (BCR).

Prostate-specific membrane antigen PET may offer non-invasive assessment of histopathological and oncological outcomes before definitive treatment. SUVmax of the dominant lesion has been explored as a prognostic biomarker. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, we performed reviews of digital libraries and databases and retrieved studies reporting SUVmax quantified on PSMA PET computed tomography or magnetic resonance imaging and subsequent radical prostatectomy ISUP Grade Group, pT stage, and BCR. Quality assessment was performed using Quality Assessment of Diagnostic Accuracy Studies-2 and Prediction model Risk of Bias Assessment tools. Random effects meta-analysis and meta-regression by ISUP Grade Group and pT2 vs pT3/4 stage was performed. This study was registered on the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023408170).

After removing duplicates, 23 studies were included for review. Pooled SUVmax (95% confidence interval [CI]) increased monotonically with advancing ISUP Grade Group, with ISUP 1: 5.8 (95% CI 3.9-7.7), through to ISUP 5: 17.3 (95% CI 13.1-21.5). For pT2 disease, pooled SUVmax: 9.7 (95% CI 7.8-11.5) increasing to 13.8 (95% CI 10.9-16.7) for pT3/4 disease. Substantial inconsistency was noted (I2 >50%) for all subgroups. This was not attenuated by restricting analysis only to studies using [68Ga]Ga-PSMA-11. Narrative synthesis of six papers reporting BCR showed increasing SUVmax was associated with reduced time to BCR.

Preoperative intraprostatic PSMA SUVmax increases monotonically with higher ISUP Grade Group and pathological tumour stage. Higher SUVmax is associated with reduced BCR-free survival. However, the use of single SUVmax thresholds for clinical decision making is not recommended as variability between studies is high.

As body mass index (BMI) increases, the quality of 2-deoxy-2-[fluorine-18]fluoro-D-glucose (18F-FDG) positron emission tomography (PET) images reconstructed with ordered subset expectation maximization (OSEM) declines, negatively impacting lesion diagnostics. It is crucial to identify methods that ensure consistent diagnostic accuracy and maintain image quality. Deep progressive learning (DPL) algorithm, an Artificial Intelligence(AI)-based PET reconstruction technique, offers a promising solution.

150 patients underwent 18F-FDG PET/CT scans and were categorized by BMI into underweight, normal, and overweight groups. PET images were reconstructed using both OSEM and DPL and their image quality was assessed both visually and quantitatively. Visual assessment employed a 5-point Likert scale to evaluate overall score, image sharpness, image noise, and diagnostic confidence. Quantitative assessment parameters included the background liver image-uniformity-index ([Formula: see text]) and signal-to-noise ratio ([Formula: see text]). Additionally, 466 identifiable lesions were categorized by size: sub-centimeter and larger. We compared maximum standard uptake value ([Formula: see text]), signal-to-background ratio ([Formula: see text]), [Formula: see text], contrast-to-background ratio ([Formula: see text]), and contrast-to-noise ratio ([Formula: see text]) of these lesions to evaluate the diagnostic performance of the DPL and OSEM algorithms across different lesion sizes and BMI categories.

DPL produced superior PET image quality compared to OSEM across all BMI groups. The visual quality of DPL showed a slight decline with increasing BMI, while OSEM exhibited a more significant decline. DPL maintained a stable [Formula: see text] across BMI increases, whereas OSEM exhibited increased noise. In the DPL group, quantitative image quality for overweight patients matched that of normal patients with minimal variance from underweight patients. In contrast, OSEM demonstrated significant declines in quantitative image quality with rising BMI. DPL yielded significantly higher contrast ([Formula: see text], [Formula: see text],[Formula: see text]) and [Formula: see text] than OSEM for all lesions across all BMI categories.

DPL consistently provided superior image quality and lesion diagnostic performance compared to OSEM across all BMI categories in 18F-FDG PET/CT scans. Therefore, we recommend using the DPL algorithm for 18F-FDG PET/CT image reconstruction in all BMI patients.

This retrospective analysis evaluates baseline 18F-flotufolastat positron emission tomography (PET) parameters as prognostic parameters for treatment response and outcome in patients with metastatic castration-resistant prostate cancer (mCRPC) undergoing treatment with [177Lu]Lu-PSMA-I&T.

A total of 188 mCRPC patients with baseline 18F-flotufolastat PET scans were included. Tumor lesions were semiautomatically delineated, with imaging parameters including volume-based and standardized uptake value (SUV)-based metrics. Outcome measures included prostate-specific antigen (PSA) response, PSA-progression-free survival (PSA-PFS), and overall survival (OS). Univariate and multivariate regression analyses assessed the impact of baseline imaging and pretherapeutic clinical parameters on outcome. Event time distributions were estimated with the Kaplan-Meier method, and groups were compared with log-rank tests.

Significant prognostic parameters for PSA response and PSA-PFS included log-transformed whole-body SUVmax (odds ratio (OR), 3.26, 95% confidence interval (CI), 2.01-5.55 and hazard ratio (HR), 0.51, 95% CI, 0.4-0.66; both p < 0.001) and prior chemotherapy (OR 0.3, 95% CI, 0.12-0.72 and HR 1.64, 95% CI, 1.07-2.58; p = 0.008 and p = 0.028, respectively). For OS, significant prognosticators were the following log-transformed parameters: number of lesions (HR 1.38, 95% CI, 1.24-1.53; p < 0.001), TTV (HR 1.27, 95% CI, 1.18-1.37; p < 0.001), and ITLV (HR 1.24, 95% CI, 1.16-1.33; p < 0.001), with log-transformed TTV (HR 1.15, 95% CI, 1.04-1.27; p = 0.008) remaining significant in multivariate analysis.

At baseline, SUV-based 18F-flotufolastat PET metrics (e.g., whole-body SUVmax) serve as significant positive prognosticators for short-term outcomes (PSA response and PSA-PFS). In contrast, volume-based metrics (e.g., TTV) are significant negative prognosticators for long-term outcome (OS), in mCRPC patients treated with [177Lu]Lu-PSMA-I&T.

It has been hypothesized that 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography (PET) computed tomography (CT) can distinguish polymyalgia rheumatica (PMR) from non-PMR patients based on the [18F]FDG-uptake patterns. Nevertheless, a comprehensive assessment of whole-body [18F]FDG-patterns across all uptaking musculoskeletal sites, as well as site-specific [18F]FDG-uptake patterns, has not been conducted. Therefore, this study aimed to investigate both the overall whole-body [18F]FDG-uptake patterns and the specific uptake patterns at individual sites in patients suspected of having PMR.

Two distinct cohorts of patients with suspected PMR from Denmark and the Netherlands were prospectively included, encompassing 66/27 and 36/21 PMR/non-PMR patients, respectively. The cohorts consisted of treatment-naïve patients, who underwent pre-treatment [18F]FDG-PET/CT scans. The [18F]FDG-uptake was then assessed across 34 different anatomical sites. Furthermore, the site-specific [18F]FDG-uptake pattern within each anatomical site was categorized according to its shape.

Patients with PMR were more likely than non-PMR patients to have bilateral [18F]FDG-uptake equal to or above liver compared at the ischial tuberosities (91%/41%), shoulder joints (86%/45%), hip joints (83%/52%), and along the lumbar spinal processes (70%/30%). However, a subgroup analysis comparing non-PMR patients with other inflammatory conditions to patients with PMR revealed that several non-PMR patients exhibited a similar whole-body [18F]FDG-uptake pattern. Furthermore, site-specific [18F]FDG-uptake patterns were similar in patients with PMR and non-PMR.

Assessing whole-body or site-specific [18F]FDG-uptake patterns does not improve the diagnostic accuracy in distinguishing PMR from other inflammatory diseases. Consequently, [18F]FDG-PET/CT should mainly be used to rule out a clinical diagnosis of PMR.

ClinicalTrials.gov (NCT04519580). Registered 17th of August 2020.

Gallium-68 (68Ga) prostate-specific membrane antigen (PSMA) ([68Ga]Ga-PSMA-11) directed PET/CT reflects PSMA expression at metastatic sites and can hence be a surrogate of lutetium-177 (177Lu) PSMA ([177Lu]Lu-PSMA) radiation delivery. This retrospective analysis aims to explore the association between quantitative baseline [68Ga]Ga-PSMA-11 PET imaging biomarkers and treatment outcomes in our Asian cohort.

We included patients with progressive metastatic castrate-resistant prostate cancer (mCRPC) who received [177Lu]Lu-PSMA radioligand therapy at our institution. The association between baseline [68Ga]Ga-PSMA-11 PET parameters (SUVmax, SUVmean, total tumor volume [PSMA-TV], total lesion uptake [PSMA-TLU = PSMA-TV × SUVmean], and total lesion quotient [PSMA-TLQ = PSMA-TV / SUVmean]) and overall survival (OS), prostate specific antigen (PSA) progression free survival (PFS), PSA response, and toxicity were analyzed using univariate analysis. Optimal cut-points were also explored.

Between May 9, 2018 and October 7, 2024, 71 of 84 screened patients were eligible. The median whole-body SUVmean in our cohort was 8.04. Higher PSMA-TLQ and PSMA-TV (per 10-unit increment) were associated with shorter OS (HR 1.005; HR 1.005) and shorter PSA PFS (HR 1.005; HR 1.004). A higher PSMA-TLQ was also associated with poorer odds of PSA response (OR 0.994). Conversely, higher SUVmean was associated with longer PSA PFS (HR 0.911) and improved odds of PSA response (OR 1.34). Higher PSMA-TV (per 10-unit increment) and PSMA-TLU (per 100-unit increment) were associated with increased hematological toxicity (OR 1.008; OR 1.012).

PSMA-TLQ and PSMA-TV were negative prognostic markers and SUVmean was a positive prognostic marker among Asian patients with mCRPC who received [177Lu]Lu-PSMA radioligand therapy.

The present study aimed to investigate the influence of the deep progressive learning reconstruction (DPR) algorithm on the 18F-FDG PET image quality and quantitative parameters.

In this retrospective study, data were collected from 55 healthy individuals and 184 patients with primary malignant pulmonary tumors who underwent 18F-FDG PET/CT examinations. PET data were reconstructed using the ordered subset expectation maximization (OSEM) and DPR algorithms. The influence of DPR algorithm on quantitative parameters was explored, including the SUVmax, SUVmean, standard deviation of SUV (SUVSD), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor-to-background uptake ratio (TBR). Finally, the differences in image quality parameters, including signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), between the two reconstruction algorithms were evaluated.

DPR algorithm significantly reduced the SUVmax and SUVSD of background tissues (all, P < 0.001) compared to OSEM algorithm, while no statistical difference was observed in SUVmean between the two algorithms (all, P > 0.05). DPR algorithm notably increased the SUVmax, SUVmean, and TBR of lesions (all, P < 0.001) and reduced MTV (P = 0.005), with minimal differences in TLG noted between the reconstruction algorithms (P < 0.001). The percentage differences in SUVmax (P = 0.001), SUVmean (P = 0.005), and TBR (P = 0.001) between the two algorithms were significantly higher in solid nodules than in pure ground glass nodules (pGGNs). The ΔCNR between solid nodules (P = 0.031) and mixed ground glass nodules (P = 0.020) was greater than that between pGGNs. SNR and CNR obtained using the DPR algorithm were markedly improved compared to those determined using the OSEM algorithm (all, P < 0.001).

Under identical acquisition conditions, the DPR algorithm enhanced the accuracy of quantitative parameters in pulmonary lesions and potentially improved lesion detectability. The DPR algorithm increased image SNR and CNR compared to those obtained using the OSEM algorithm, significantly optimizing overall image quality. This advancement facilitated precise clinical diagnosis, underpinning its potential to significantly contribute to the field of medical imaging.

[18F]FDG uptake in the livers and tumors of children is lower than that of adults. The brain exhibits intense physiological [18F]FDG uptake. In childhood, the ratio of brain weight to body height and the ratio of brain weight to body weight are higher than those of adults. We hypothesized that in children, most of the [18F]FDG would be retained in the brain, resulting in less [18F]FDG activity reaching other organs and tumor tissues.

The [18F]FDG PET/CT images of 56 pediatric and 24 adult patients were evaluated retrospectively. Patients were divided into four age groups: 1) 3-7 years old, 2) 8-12 years old, 3) 13-17 years old, and 4) over 18 years old. Accumulated [18F]FDG activity in the brain, liver, and whole body (WB) was calculated using the manually drawn volumes of interest for all patients using NUKDOS software. Also, SUV normalized to total body weight (SUVbw) and SUV normalized to lean body mass (SUVlbm) of the liver were calculated using the NUKDOS software.

The mean [18F]FDG accumulation ratio of brain-to-WB was significantly higher in patients aged 3-7 years and 8-12 years than in adults. Brain/WB [18F]FDG activity ratio was lower in the 13-17 age group compared to the 3-7 age group (P = .0001). The accumulated [18F]FDG activity ratio of liver-to-WB in the 3-7 age group was significantly lower than in adults when comparing the four groups (P = .0001). The mean of liver SUVbw was statistically lower in the 3-7 and 8-12 age groups than in the 13-17 and adult groups. Patients aged 3-7 years had a significantly lower mean liver SUVlbm than those in the other age groups. The mean liver SUVlbm was also significantly lower in the 8-12 years and 13-17 years age groups than in adults. There was a negative correlation between blood glucose levels and the amount of [18F]FDG in the brain. However, no statistically significant correlation existed between blood glucose and age.

We showed that the [18F]FDG accumulation rate was higher in the brain and lower in the liver in the children when compared to adults. Our findings suggest that increased uptake of [18F]FDG in children's brains may lead to reduced activity reaching other organs and tumor tissue. To improve diagnostic accuracy, adapted SUV correction protocols can be developed for pediatric populations, considering age-related changes in [18F]FDG uptake ratio of the brain.

18F-Fluorodeoxyglucose (FDG) PET/CT is emerging as a tool in the diagnosis and evaluation of pulmonary sarcoidosis, however, there is limited consensus regarding its diagnostic performance and prognostic value.

A meta-analysis was conducted with PubMed, Science Direct, MEDLINE, Scopus, and CENTRAL databases searched up to and including September 2023. 1355 studies were screened, with seventeen (n = 708 patients) suitable based on their assessment of the diagnostic performance or prognostic value of FDG-PET/CT. Study quality was assessed using the QUADAS-2 tool. Forest plots of pooled sensitivity and specificity were generated to assess diagnostic performance. Pooled changes in SUVmax were correlated with changes in pulmonary function tests (PFT).

FDG-PET/CT in diagnosing suspected pulmonary sarcoidosis (six studies, n = 400) had a pooled sensitivity of 0.971 (95%CI 0.909-1.000, p = < 0.001) and specificity of 0.873 (95%CI 0.845-0.920)(one study, n = 169). Eleven studies for prognostic analysis (n = 308) indicated a pooled reduction in pulmonary SUVmax of 4.538 (95%CI 5.653-3.453, p = < 0.001) post-treatment. PFTs displayed improvement post-treatment with a percentage increase in predicted forced vital capacity (FVC) and diffusion capacity of the lung for carbon monoxide (DLCO) of 7.346% (95%CI 2.257-12.436, p = 0.005) and 3.464% (95%CI -0.205-7.132, p = 0.064), respectively. Reduction in SUVmax correlated significantly with FVC (r = 0.644, p < 0.001) and DLCO (r = 0.582, p < 0.001) improvement.

In cases of suspected pulmonary sarcoidosis, FDG-PET/CT demonstrated good diagnostic performance and correlated with functional health scores. FDG-PET/CT may help to guide immunosuppression in cases of complex sarcoidosis or where treatment rationalisation is needed.

FDG-PET/CT has demonstrated a high diagnostic performance in the evaluation of suspected pulmonary sarcoidosis with radiologically assessed disease activity correlating strongly with clinically derived pulmonary function tests.

In diagnosing pulmonary sarcoidosis, FDG-PET/CT had a sensitivity and specificity of 0.971 and 0.873, respectively. Disease activity, as determined by SUVmax, reduced following treatment in all the included studies. Reduction in SUVmax correlated with an improvement in functional vital capacity, Diffusion Capacity of the Lungs for Carbon Monoxide, and subjective health scoring systems.

To evaluate the predictive value of standardized uptake value (SUV) in both primary tumors and axillary lymph nodes (ALNs) using FDG PET/CT for lymph node metastasis in breast cancer patients, and to assess the influence of molecular subtypes on this predictive performance.

This retrospective study included 287 patients with invasive ductal carcinoma (IDC) who underwent FDG PET/CT prior to surgery between September 2016 and December 2019. The maximum standardized uptake value (SUVmax) of primary tumors (SUV-B) and ALNs (SUV-LN) were analyzed. Molecular subtypes were classified as hormone receptor-positive, HER2-positive, and triple-negative breast cancer (TNBC). Receiver operating characteristic (ROC) curve analysis was performed to assess and compare the diagnostic performance of SUV-B and SUV-LN for predicting ALN metastasis.

Among the 287 patients, 62 (21.6%) had confirmed ALN metastasis. The median SUV-LN was significantly higher in patients with metastasis compared to those without metastasis (1.5 vs. 0.9; P < 0.001). SUV-LN demonstrated good discriminative performance for ALN metastasis (AUC: 0.796), whereas SUV-B did not show significant predictive value (AUC: 0.536). The SUV_LN demonstrated significantly lower predictive performance for ALN metastasis in the hormone-positive group (AUC: 0.796) compared to the excellent discriminative performance in the HER2-positive (AUC: 0.923, P = 0.018) and TNBC (AUC: 0.940, P = 0.004) groups. Hormone receptor-positive tumors also exhibited lower FDG uptake in metastatic lymph nodes compared to HER2-positive and TNBC subtypes (P = 0.031).

FDG PET/CT SUV-LN effectively predicts ALN metastasis in HER2-positive and TNBC subtypes. Hormone receptor-positive breast cancers show lower FDG uptake in metastatic ALNs, reducing diagnostic accuracy. This finding may aid in selecting the most appropriate diagnostic modality based on tumor characteristics in the era of personalized medicine.

Radiation-induced injuries (RIIs) are significant complications of radiation therapy used in cancer treatments and affect organs in a systemic fashion such as the heart, lungs, liver, and bone marrow. Such ionizing radiation leads to inflammation, fibrosis, and/or irreparable DNA damage, each of which can significantly impact patient's quality of life, underscoring the need for advanced diagnostic and imaging techniques. A novel combination of PET/Computed Tomography (CT) with Quantitative MR Imaging has emerged as a crucial tool for early diagnosis and timely evaluation of RIIs. This review focuses on the important role of quantitative PET-CT-MR imaging in diagnosing and monitoring RIIs.

Background: Hypoxia plays a critical role in lung cancer progression and treatment resistance by contributing to aggressive tumor behavior and poor therapeutic response. Molecular imaging, particularly positron emission tomography (PET), has become an essential tool for noninvasive hypoxia detection, providing valuable insights into tumor biology and aiding in personalized treatment strategies. Objective: This narrative review explores recent advancements in PET imaging for detecting hypoxia in lung cancer, with a focus on the development, characteristics, and clinical applications of various radiotracers. Findings: Numerous PET-based hypoxia radiotracers have been investigated, each with distinct pharmacokinetics and imaging capabilities. Established tracers such as 18F-Fluoromisonidazole (18F-FMISO) remain widely used, while newer alternatives like 18F-Fluoroazomycin Arabinoside (18F-FAZA) and 18F-Flortanidazole (18F-HX4) demonstrate improved clearance and image contrast. Additionally, 64Cu-ATSM has gained attention for its rapid tumor uptake and hypoxia selectivity. The integration of PET with hybrid imaging modalities, such as PET/CT and PET/MRI, enhances the spatial resolution and functional interpretation, making hypoxia imaging a promising approach for guiding radiotherapy, chemotherapy, and targeted therapies. Conclusions: PET imaging of hypoxia offers significant potential in lung cancer diagnosis, treatment planning, and therapeutic response assessment. However, challenges remain, including tracer specificity, quantification variability, and standardization of imaging protocols. Future research should focus on developing next-generation radiotracers with enhanced specificity, optimizing imaging methodologies, and leveraging multimodal approaches to improve clinical utility and patient outcomes.

Mediastinal lymph node (LN) staging is routinely performed using PET/CT and EBUS-TBNA. Promising predictive algorithms for lymph nodes have been reported for each technique, both individually and in combination. This study aims to develop a predictive algorithm that combines EBUS, PET/CT and clinical data to provide a probability of malignancy.

A retrospective study was conducted on consecutive patients with non-small cell lung carcinoma staged using PET/CT and EBUS-TBNA. Lymph nodes were identified by level (N1, N2, and N3) and anatomical region (AR) (subcarinal, paratracheal, and hilar). A Standardized Uptake Value (SUV) was determined for each sampled LN. The ultrasound features collected included diameter in the short axis (DSA), morphology, border, echogenicity and the presence of the vascular hilum. A robust logistic regression model was used to construct an algorithm to estimate the probability of malignancy of the lymph node.

A total of 116 patients with a mean age of 66, 93% of whom were men, were included. 358 lymph nodes were evaluated, 51% of which exhibited adenocarcinoma and 35% were squamous, while 14% were classified as non-small-cell lung carcinoma. The model estimated the probability of malignancy for each lymph node using age, DSA, SUVmax, and AR. The Area Under the ROC curve, was 0.89. A user-friendly application was also developed ( https://ubidi.shinyapps.io/lymma/ .) CONCLUSIONS: The integration of patient clinical characteristics, EBUS features, and PET/CT findings may generate a pre-sampling malignancy probability map for each lymph node. The model requires prospective and external validation.

To minimize radiation exposure while obtaining high-quality Positron Emission Tomography (PET) images, various methods have been developed to derive standard-count PET (SPET) images from low-count PET (LPET) images. Although deep learning methods have enhanced LPET images, they rarely utilize the rich complementary information from MR images. Even when MR images are used, these methods typically employ early, intermediate, or late fusion strategies to merge features from different CNN streams, failing to fully exploit the complementary properties of multimodal fusion.

In this study, we introduce a novel multimodal feature-guided diffusion model, termed MFG-Diff, designed for the denoising of LPET images with the full utilization of MRI.

MFG-Diff replaces random Gaussian noise with LPET images and introduces a novel degradation operator to simulate the physical degradation processes of PET imaging. Besides, it uses a novel cross-modal guided restoration network to fully exploit the modality-specific features provided by the LPET and MR images and utilizes a multimodal feature fusion module employing cross-attention mechanisms and positional encoding at multiple feature levels for better feature fusion.

Under four counts (2.5%, 5.0%, 10%,  and 25%), the images generated by our proposed network showed superior performance compared to those produced by other networks in both qualitative and quantitative evaluations, as well as in statistical analysis. In particular, the peak-signal-to-noise ratio of the generated PET images improved by more than 20% under a 2.5% count, the structural similarity index improved by more than 16%, and the root mean square error reduced by nearly 50%. On the other hand, our generated PET images had significant correlation (Pearson correlation coefficient, 0.9924), consistency, and excellent quantitative evaluation results with the SPET images.

The proposed method outperformed existing state-of-the-art LPET denoising models and can be used to generate highly correlated and consistent SPET images obtained from LPET images.

The maximum standardised uptake value (SUVmax) can potentially be affected by the uptake period during PSMA PET imaging. The optimal image acquisition period for 2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL)PSMA PET/CT is yet to be established. This study aims to evaluate the effect of the uptake period on the SUVmax in diagnosing localised, clinically significant prostate cancer using 18F-DCFPyL-PSMA PET/CT.

Sixty biopsy-naive men with one or more PI-RADS 4 or 5 lesions of at least 10 mm on multiparametric MRI (mpMRI) were enrolled to undergo 18F-DCFPyL-PSMA PET/CT. SUVmax was prospectively measured following an uptake period of 60, 90 and 120 min post injection of 18F-DCFPyL-PSMA radiotracer. Concordance with biopsy results or final histopathology was recorded.

Mean absolute differences in SUVmax at 60 vs. 90, 60 vs. 120, and 90 vs. 120 min uptake periods were 3.23 (SD 4.76), 4.53 (SD 7.33), and 3.24 (SD 4.56), respectively. This represents a statistically significant systematic increase in SUVmax (p-value < 0.001) with increasing uptake period. The interval between the uptake period of 60 vs. 120 min represented the largest SUVmax change of 29.98%.

The SUVmax is a dynamic variable significantly affected by uptake period. Our study supports image acquisition at 120 min following injection of 18F-DCFPyL radiotracer. Further studies are needed to determine if this acquisition period can be applied to other Fluorine-18 based PSMA radiotracers.

Androgen receptor-targeting agents, particularly enzalutamide, show promise in enhancing prostate cancer diagnostic and therapeutic strategies by modulating prostate-specific membrane antigen (PSMA). Methods: A retrospective clinical cohort study investigated 9 men with metastatic castration-resistant prostate cancer on enzalutamide. PSMA PET/CT scans were obtained before and after enzalutamide initiation to assess PSMA expression changes. Lesions and organs at risk were evaluated visually and semiquantitatively. The flare phenomenon was characterized by a significant increase (≥20%) in the SUVmax of existing lesions or the appearance of new PSMA-positive lesions. Results: Exposure to enzalutamide led to a significant PSMA expression increase in 56% of assessed lesions (n = 42), with new lesions detected in 1 patient (11%). PSMA expression in organs at risk remained largely unaffected, indicating a tumor-specific response. Conclusion: Enzalutamide induces PSMA upregulation in metastatic castration-resistant prostate cancer, potentially enhancing diagnostic and therapeutic strategies. Further exploration of the flare phenomenon's clinical implications is warranted.

The purpose of this systematic review was to evaluate the role of PSMA PET/CT in intermediate-risk prostate cancer (PCa) patients, to determine whether it could help improve treatment strategy and prognostic stratification. A systematic literature search up to May 2024 was conducted in the PubMed, Embase and Scopus databases. Articles with mixed risk patient populations, review articles, editorials, letters, comments, or case reports were excluded. The quality of the papers was assessed by using the CASP criteria. The literature search returned 1111 studies; however, 1105 articles were excluded, and therefore 6 full-text papers were retrieved for the final analysis. Three out of six papers focused on the utility of SUVmax in identifying high ISUP grade in patients with intermediate-risk PCa. The latest three papers discussed the controversial role of PSMA PET/CT in predicting the lymph node involvement, mainly in the case of favorable subset. PSMA PET has completely changed the management of patients with PCa; indeed its role is still undefined in patients with intermediate-risk disease. Future perspective is to investigate larger cohorts of intermediate-risk PCa patients, to fully recognize the added value offered by PSMA PET in this category of subjects.

Background: This study aimed to investigate the clinical and prognostic significance of preoperative maximum standardized uptake value (SUVmax) and GLUT-1 expression in patients with advanced gastric cancer (AGC). Methods: Medical records of patients who were diagnosed with AGC between 2018 and 2020 at Zhongshan Hospital of Fudan University (Shanghai, China) were retrospectively analyzed. Finally, 182 patients were enrolled, and for each patient, SUVmax was calculated for the primary lesion on PET/CT prior to curative surgery. A total of 165 clinical tissue specimens were collected for immunohistochemical analysis of GLUT-1 expression. Results: A total of 182 patients were divided into two groups based on their SUVmax values. The low SUVmax group comprised 92 patients. Patients with low SUVmax tended to be younger and included a higher proportion of women, with their primary tumors typically smaller or in earlier TNM stages. The median follow-up time was 52 months. The 1-, 3-, and 5-year progression-free survival (PFS) rates were 90.7%, 71.4%, and 67.0%, respectively. Among them, 33 patients experienced recurrence and metastasis, and 40 ultimately died. Log-rank analysis revealed that the low SUVmax group exhibited superior progression-free survival (PFS) and overall survival (OS). Multivariate analysis indicated that, for AGC without preoperative treatment, later stage (stage III) was independently correlated with a higher risk of recurrence (HR = 3.049; 95%CI = 1.076-8.639; p = 0.036), while the low SUVmax group exhibited a reduced risk of recurrence and mortality compared with the high SUVmax group (HR = 0.565; 95%CI = 0.326-0.979; p = 0.042). Conclusions: The clinicopathological characteristics of patients with AGC with different SUVmax values appeared significantly different. Tumor stage and SUVmax were found as independent factors affecting postoperative recurrence and death of patients with AGC.

Objectives: This retrospective study explored the qualitative and quantitative assessment of F18-fluordeoxyglucose ([18F]-FDG) positron emission tomography and computed tomography (PET/CT) scans to assess pathophysiological muscle glucose uptake in patients with a rheumatic musculoskeletal disease (RMD). [18F]-FDG PET/CT detects metabolic activity via glucose uptake in tissues. This study aimed to determine the feasibility of quantitative assessment of [18F]-FDG uptake in muscles across three different RMDs compared to controls. Methods: In this study we analysed whole-body [18F]-FDG PET/CT scans from patients with rheumatoid arthritis (RA; n = 11), osteoarthritis (OA; n = 10), and idiopathic inflammatory myositis (IIM; n = 10), and non-RMD controls (n = 11), focusing on muscle-tracer uptake in specific muscle groups. Qualitative assessment visually identified regions with high [18F]-FDG uptake, followed by quantitative assessment using two methods: fixed volume-of-interest (VOI) and hotspot VOI. In the fixed VOI method, a VOI was placed in the respective muscle at a fixed position (50% height from proximal to distal end) on PET/CT images. In the hotspot VOI method, the VOI was placed at the site of the highest [18F]-FDG uptake observed during qualitative assessment. Standardised uptake values (SUVs) were determined for different muscle groups between RMDs and controls. Results: Qualitative assessment revealed a heterogenous uptake pattern of [18F]-FDG that was found in 93% of quadriceps and hamstring muscles, while other muscles displayed either heterogenous or homogenous patterns. A Bland-Altman analysis showed that the hotspot VOI method had a higher sensitivity in detecting differential [18F]-FDG uptake in muscles. Across all muscle groups, patients with IIM had the highest [18F]-FDG uptake, followed by patients with OA and RA, respectively. Conclusions: [18F]-FDG PET/CT enables qualitative and quantitative differentiation of muscle glucose uptake in patients with RA, OA, and IIM, at both individual muscle and patient group levels. The hotspot method and SUVpeak are recommended for quantitative assessment. High [18F]-FDG uptake in multiple muscle groups suggests pathophysiological glucose metabolism in RMD-affected muscles.

Misregistration artifacts between the PET and attenuation correction CT (CTAC) exams can degrade image quality and cause diagnostic errors. Deep learning (DL)-warped elastic registration methods have been proposed to improve misregistration errors.

30 patients undergoing routine oncologic examination (20 18F-FDG PET/CT and 10 64Cu-DOTATATE PET/CT) were retrospectively identified and compared using unmodified CTAC, and a DL-augmented spatial transformation CT attenuation map. Primary endpoints included differences in subjective image quality and standardized uptake values (SUV). Exams were randomized to reduce reader bias, and three radiologists rated image quality across six anatomic sites using a modified Likert scale. Measures of local bias and lesion SUV were also quantitatively evaluated.

The DL attenuation correction methods were associated with higher image quality and reduced misregistration artifacts (Mean 18F-FDG quality rating=3.5-3.8 for DL vs 3.2-3.5 for standard reconstruction (STD); Mean 64Cu-DOTATATE quality rating= 3.2-3.4 for DL vs 2.1-3.3; P < 0.05 for STD, for all except 64Cu-DOTATATE inferior spleen). Percent change in superior liver SUVmean for 18F-FDG and 64Cu-DOTATATE were 5.3 ± 4.9 and 8.2 ± 4.1%, respectively. Measures of signal-to-noise ratio were significantly improved for the DL over STD (Hepatopulmonary index (HPI) [18F-FDG] = 4.5 ± 1.2 vs 4.0 ± 1.1, P < 0.001; HPI [64Cu-DOTATATE] = 16.4 ± 16.9 vs 12.5 ± 5.5, P = 0.039).

Deep learning elastic registration for CT attenuation correction maps on routine oncology PET/CT decreases misregistration artifacts, with a greater impact on PET scans with longer acquisition times.

This guideline outlines the use of 3,4-dihydroxy-6-18F-fluoro-L-phenylalanine positron emission tomography / computed tomography for the diagnosis and management of neuroendocrine tumors, brain tumors, and other tumorous conditions. It provides detailed recommendations on patient preparation, imaging procedures, and result interpretation. Based on international standards and adapted to local clinical practices, the guideline emphasizes safety, quality control, and the effective application of 3,4-dihydroxy-6-18F-fluoro-L-phenylalanine positron emission tomography / computed tomography for various tumors such as insulinomas, pheochromocytomas, and medullary thyroid carcinoma. It also addresses the use of premedication with carbidopa, fasting protocols, and optimal imaging techniques. The aim is to assist nuclear medicine professionals in delivering precise diagnoses, improving patient outcomes, and accommodating evolving medical knowledge and technology. This comprehensive document serves as a practical resource to enhance the accuracy, quality, and safety of 3,4-dihydroxy-6-18F-fluoro-L-phenylalanine positron emission tomography / computed tomography in oncology.

This study aimed to optimize the quantitative aspects of (18F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging by investigating the impact of various reconstruction parameters on the recovery coefficients (RCs) using the NEMA image quality phantom. Specifically, the study aims to assess how different matrix sizes, iterations, subsets, and Gaussian postfilters affect the accuracy of standardized uptake value (SUV) quantification in (18F) FDG PET/CT imaging.

The study utilized the "Vue Point FX + Sharp IR" algorithm for PET image reconstruction, incorporating 3D-ordered subset expectation maximization (3D-OSEM), time-of-flight, and point spread function technologies. Various reconstruction parameters were explored, including two distinct matrix sizes, multiple iterations, subsets, and a wide range of Gaussian postfilters. The investigation focused on the impact of these parameters on RCs using the NEMA image quality phantom.

The results of the study indicated that for accurate SUV quantification in spheres ≥17 mm, the 256 × 256 matrix size and mean SUV should be employed. Conversely, for spheres ≤13 mm, maximum SUV was found to be more suitable. The choice of postfiltering value was shown to have a significant impact on SUV quantification accuracy, particularly for small-sized spheres. In addition, a larger matrix size was found to partially mitigate the effects of Gibbs artifact and slightly enhance SUV quantification for the spheres of various sizes.

This study highlights the critical importance of optimizing PET reconstruction parameters in accordance with the guidelines set by European Association of Nuclear Medicine/EARL. By optimizing these parameters, the accuracy and reliability of SUV quantification in (18F) FDG PET imaging can be significantly enhanced, especially for small-sized spheres. This underscores the necessity of carefully considering reconstruction parameters to ensure precise and reliable quantitative measurements in PET/CT imaging.

In veterinary medicine, PET/CT scans are generally performed with the patient under general anesthesia. The aim of this prospective crossover study was to compare the musculoskeletal uptake of 18F-FDG and radiation doses to workers during PET/CT studies of healthy dogs and cats between sedation and general anesthesia. Volume and maximal standard uptake values (SUVmax) values of abnormal 18F-FDG uptake in the skeletal musculature, presence of misregistration artifact, and radiation doses to workers for each PET/CT study were recorded. Sedation was associated with increased volume of 18F-FDG uptake in the musculature of the thoracic limbs (p = .01), cervical (p = .02), and thoracic (p = .03) spine. Increased volume and SUVmax of the musculature assessed altogether were associated with the lighter degree of sedation (p = .04 for both). A significant decrease in the odds of misregistration artifact was observed for anesthetized animals in comparison with sedated (OR: 0.0, 95% CI: 0.0-0.0, p = .01). Radiation doses to workers were significantly higher for sedation compared with general anesthesia (p = .01) and for the anesthesia technician compared with the nuclear medicine technologist (p = .01). Use of sedation for PET/CT studies in dogs and cats is feasible. However, it is associated with increased physiologic musculoskeletal uptake of 18F-FDG in the thoracic limbs, cervical, and thoracic spine, with increased frequency of misregistration artifact, and with increased radiation doses to workers. These limitations can be overcome by recognition of the uptake pattern and monitoring/rotation of the involved staff at institutions where a high caseload is expected.

Sarcoidosis is a systemic disorder characterized by non-necrotizing granulomatous inflammation and fibrosis affecting multiple organs, notably the lungs and lymph nodes. Cardiac sarcoidosis (CS), a subset of the disease predominantly involving the heart, significantly heightens the associated morbidity and mortality of sarcoidosis. Early detection of CS is crucial for optimal management. Positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose (18F-FDG) has emerged as an important diagnostic, prognostic, and monitoring tool for CS. Guidelines emphasize a combined approach of visual interpretation and adjunctive quantitative metrics to enhance diagnostic accuracy and treatment monitoring. Various quantitative parameters including maximum standardized uptake value (SUVmax), coefficient of variation, and texture analysis show promise as auxiliary tools diagnosing and prognosticating CS. However, standardization and validation of these quantitative methods remain challenging due to inter-center variability and technological differences. Further validation through large-scale, multi-center studies is needed to optimize their use and better delineate their role in CS diagnosis, prognostication, and therapy monitoring.

Brown adipose tissue (BAT) plays a crucial role in energy expenditure and thermoregulation and has thus garnered interest in the context of metabolic diseases. Segmentation in medical imaging is time-consuming and prone to inter- and intra-operator variability. This study aims to develop an automated BAT segmentation method using the nnU-Net deep learning framework, integrated into the TotalSegmentator software, and to evaluate its performance in a large cohort of patients with lymphoma.

A 3D nnU-Net model was trained on the manually annotated BAT regions from 159 lymphoma patients' CT scans, employing a 5-fold cross-validation approach. An ensemble model was created using these folds to enhance segmentation performance. The model was tested on an independent cohort of 30 patients. The evaluation metrics included the DICE score and Hausdorff Distance (HD). Additionally, the mean standardized uptake value (SUV) in the BAT regions was analyzed in 7107 FDG PET/CT lymphoma studies to identify patterns in the BAT SUVs.

The ensemble model achieved a state-of-the-art average DICE score of 0.780 ± 0.077 and an HD of 29.0 ± 14.6 mm in the test set, outperforming the individual fold models. Automated BAT segmentation revealed significant differences in the BAT SUVs between the sexes, with higher values in women. The morning scans showed a higher BAT SUV compared to the afternoon scans, and seasonal variations were observed, with an increased uptake during the winter. The BAT SUVs decreased with age.

The proposed automated BAT segmentation tool demonstrates robust performance, reducing the need for manual annotation. The analysis of a large patient cohort confirms the known patterns of BAT SUVs, highlighting the method's potential for broader clinical and research applications.

To construct and externally calibrate a predictive model for early biochemical recurrence (BCR) after radical prostatectomy (RP) incorporating clinical and modern imaging characteristics of the primary tumour.

Patients who underwent RP following multiparametric magnetic resonance imaging, prostate biopsy and prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT), from two centres in Australia and the Netherlands. The primary outcome was biochemical recurrence-free survival (BRFS), where BCR was defined as a rising PSA level of ≥0.2 ng/mL or initiation of postoperative treatment per clinician discretion. Proportional hazards models to predict time to event were developed in the Australian sample using relevant pre- and post-surgical parameters and primary tumour maximum standardised uptake value (SUVmax) on diagnostic PSMA-PET/CT. Calibration was assessed in an external dataset from the Netherlands with the same inclusion criteria.

Data from 846 patients were used to develop the models. Tumour SUVmax was associated with worse predicted 3-year BRFS for both pre- and post-surgical models. SUVmax change from 4 to 16 lessened the predicted 3-year BRFS from 66% to 42% for a patient aged 65 years with typical pre-surgical parameters (PSA level 8 ng/mL, Prostate Imaging-Reporting and Data System score 4/5 and biopsy Gleason score ≥4 + 5). Considering post-surgical variables, a patient with the same age and PSA level but pathological stage pT3a, RP Gleason score ≥4 + 5 and negative margins, SUVmax change from 4 to 16 lessened the predicted 3-year BRFS from 76% to 61%. Calibration on an external sample (n = 464) showed reasonable performance; however, a tendency to overestimate survival in patients with good prognostic factors was observed.

Tumour SUVmax on diagnostic PSMA-PET/CT has utility additional to commonly recognised variables for prediction of BRFS after RP.

This study evaluates the impact of partial volume effect (PVE) correction on [18F]fluoromisonidazole (FMISO) PET images, focusing on the conversion of standardized uptake values (SUV) to partial oxygen pressure (pO2) and the subsequent determination of hypoxic tumor volume (HTV).

FMISO PET images from 49 head and neck squamous cell carcinoma cases were retrospectively corrected for PVE and converted to pO2. A pO2 threshold of 10 mmHg was used to delineate the HTV (HTVpO2). Comparisons of pO2 distribution and HTVpO2 between corrected and uncorrected images were made, with pO2 distributions evaluated against published polarographic data. HTVpO2 was compared to HTV defined by the conventional tumor-to-muscle ratio (TMR) method (HTVTMR) in terms of volume and topography (DICE coefficient, Hausdorff distance, and center-of-gravity distance) across different TMR cutoff levels. The cutoff level where the segmentation results from both methods were most similar was identified (TMRbest).

The PVE correction led to decreased minimum pO2, increased HTVpO2 and the identification of more hypoxic cases (HTV > 0). The pO2 distribution demonstrated improved alignment with published polarographic data. At TMRbest 1.6, the center-of-gravity distance between HTVTMR and HTVpO2 demonstrated a low median at 1.5 mm, while the wide range (0.0 to 9.6 mm) indicated high interpatient variability. The shape of HTV exhibited considerable variation with DICE 0.74 (0.03 to 1.00) and Hausdorff distance 8.5 mm (2.0 to 42.8 mm).

PVE correction is recommended before converting SUV to pO2 for the spatially resolved quantification of hypoxia.

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb) and typically infects the lungs. However, extrapulmonary forms of TB can be found in approximately 20% of cases. It is suggested, that up to 10% of extrapulmonary TB affects the musculoskeletal system, in which spinal elements (spinal tuberculosis, STB) are involved in approximately 50% of the cases. STB is a debilitating disease with nonspecific symptoms and diagnosis is often delayed for months to years. In our Spinal TB X Cohort, we aim to describe the clinical phenotype of STB using whole-body 18 F-fluorodeoxyglucose positron emission tomography computed tomography (PET/CT) and to identify a specific gene expression profile for the different stages of dissemination on PET/CT. Here we report on the first patient recruited into our cohort who underwent PET/CT before treatment initiation, at 6-months and at 12-months - time of TB treatment completion.

A 27-year-old immunocompetent male presented with severe thoracolumbar back pain for 9 months with severe antalgic gait and night sweats. Magnetic resonance imaging (MRI) of the whole spine revealed multilevel spinal disease (T5/6, T11/12, L3/4) in keeping with STB. After informed consent and recruitment into the Spinal TB X Cohort, the patient underwent PET/CT as per protocol, which revealed isolated multilevel STB (T4-7, T11/12, L3/4) with no concomitant lung or urogenital lesion. However, sputum and urine were Xpert MTB/RIF Ultra positive and Mtb was cultured from the urine sample. CT-guided biopsy of the T11/12 lesion confirmed drug-sensitive Mtb on Xpert MTB/RIF Ultra and the patient was started on TB treatment according to local guidelines for 12 months. The 6-month follow-up PET/CT revealed new and existing spinal lesions with increased FDG-uptake despite significant improvement of clinical features and laboratory markers. After 9 months of treatment, the patient developed an acute urethral stricture, most likely due to urogenital TB, and a suprapubic catheter was inserted. The 12-month PET/CT showed significantly decreased PET/CT values of all lesions, however, significant persistent spinal inflammation was present at the end of TB treatment. Clinically, the patient was considered cured by the TB control program and currently awaits urethroplasty.

In our case, PET/CT emerged as a valuable imaging modality for the initial assessment, surpassing MRI by revealing more comprehensive extensive disease. Subsequent PET/CT scans at 6-month uncovered new lesions and increased inflammation in existing ones, while by the end of TB treatment, all lesions exhibited improvement. However, the interpretation of FDG avidity remains ambiguous, whether it correlates with active infection and viable Mtb. or fibro- and osteoblast activity indicative of the healing process. Additionally, the absence of extraspinal TB lesions on PET/CT despite positive microbiology from sputum and urine maybe explained by paucibacillary, subclinical infection of extraspinal organs. The Spinal TB X Cohort endeavours to shed light on whole-body imaging patterns at diagnosis, their evolution midway through TB treatment, and upon treatment completion. Ultimately, this study aims to advance our understanding of the biology of this complex disease.

Modern PET reconstruction algorithms incorporate point-spread-function (PSF) correction to mitigate partial volume effect. However, PSF correction can introduce edge artifacts that lead to quantification errors. Consequently, current international guidelines advise against using PSF correction in brain PET reconstruction.

We aimed to investigate PSF-induced quantification errors in recent digital PET systems and identify conditions that mitigate them. This study utilized brain PET imaging with alginate-based realistic phantoms, simulating lesion-to-background activity ratios of 10:1 and 2:1, with eleven reconstruction parameter sets.

Phantoms were prepared using a commercial anthropomorphic head phantom and two homemade inserts. Each insert contained a homogeneous 18F-FDG alginate background with hot spheres of varying diameter (3, 4, 6, 8, 10, 12, and 15 mm). PET imaging was conducted on a digital PET-CT system Biograph Vision 600 (Siemens), with a 10 min scan duration. Imaging was performed with and without PSF correction, with 2, 4, 6, 12, 18, or 24 iterations in reconstruction, and with or without additional Gaussian postfiltering. We assessed the recovery coefficient (RC), contrast recovery coefficient (CRC), variability, and CRC-to-variability ratios for each sphere size and reconstruction parameter set.

PSF-corrected images of the 10:1 spheres exhibited a nonmonotonic CRC-to-sphere diameter relationship due to edge artifacts overshoot in the 10 mm-diameter sphere. In contrast, PSF images of the 2:1 spheres showed a monotonically increasing relationship. Non-PSF images of both phantoms showed an expected monotonically increasing CRC-to-sphere diameter relationship but with lower CRC values compared to PSF images. The nonmonotonic relationship observed with 10:1 spheres was mitigated by applying a 3-mm FWHM Gaussian postfiltering. For both phantoms, reconstructions with 6 iterations, PSF correction, and additional 3-mm FWHM Gaussian postfiltering demonstrated the highest CRC-to-variability ratios.

Our findings indicate that Gaussian postfiltering suppresses PSF artifacts. This parameter set corrected the nonmonotonic CRC-to-sphere diameter relationship and improved the CRC-to-variability ratio compared to non-PSF reconstructions. Therefore, to enhance lesion detectability without compromising quantification accuracy, PSF correction coupled with Gaussian postfiltering should be used in brain PET.

Evidence-based treatment decisions for advanced gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) require individualized patient-centered decision-making that accounts for patient and cancer characteristics.

To create an accessible guidance document to educate clinicians and patients on biomarkers informing prognosis and treatment in unresectable or metastatic GEP-NENs.

A multidisciplinary panel in-person workshop was convened to define methods. English language articles published from January 2016 to January 2023 in PubMed (MEDLINE) and relevant conference abstracts were reviewed to investigate prognostic and treatment-informing features in unresectable or metastatic GEP-NENs. Data from included studies were used to form evidence-based recommendations. Quality of evidence and strength of recommendations were determined using the Grading of Recommendations, Assessment, Development and Evaluations framework. Consensus was reached via electronic survey following a modified Delphi method.

A total of 131 publications were identified, including 8 systematic reviews and meta-analyses, 6 randomized clinical trials, 29 prospective studies, and 88 retrospective cohort studies. After 2 rounds of surveys, 24 recommendations and 5 good clinical practice statements were developed, with full consensus among panelists. Recommendations focused on tumor and functional imaging characteristics, blood-based biomarkers, and carcinoid heart disease. A single strong recommendation was made for symptomatic carcinoid syndrome informing treatment in midgut neuroendocrine tumors. Conditional recommendations were made to use grade, morphology, primary site, and urinary 5-hydroxyindoleacetic levels to inform treatment. The guidance document was endorsed by the Commonwealth Neuroendocrine Tumour Collaboration and the North American Neuroendocrine Tumor Society.

The study results suggest that select factors have sufficient evidence to inform care in GEP-NENs, but the evidence for most biomarkers is weak. This article may help guide management and identify gaps for future research to advance personalized medicine and improve outcomes for patients with GEP-NENs.

Objectives: We compared the value of the semiquantitative parameters of 68Ga-labeled FAP inhibitor (68Ga-FAPI)-04 positron emission tomography/computed tomography (PET/CT) and 18F-fluorodeoxyglucose (18F-FDG) in diagnosing primary malignant and benign diseases. Materials and Methods: 18F-FDG and 68Ga-FAPI-04 PET/CT images of 80 patients were compared. Semiquantitative parameters, including maximum standardized uptake value (SUVmax), mean SUV (SUVmean), peak SUV (SUVpeak), peak SUV by lean body mass (SULpeak), metabolic tumor volume (or tumor volume of FAPI; FAPI-TV), and TLG (or total lesion activity of FAPI; FAPI-TLA), were automatically obtained using the IntelliSpace Portal image processing workstation with a threshold of 40% SUVmax. The liver blood pool was measured as the background, and the tumor-to-background ratio (TBRliver) was calculated. Results: In all malignant lesions, FAPI-TV and FAPI-TLA were higher in 68Ga-FAPI-04 PET/CT than in 18F-FDG. In the subgroup analysis, 68Ga-FAPI-04 had higher FAPI-TV and FAPI-TLA and lower SUVmax than 18F-FDG had in group A, including gynecological tumor, esophageal, and colorectal cancers. However, six semiquantitative parameters were higher in group B (the other malignant tumors). For the benign diseases, SUVmax, SUVmean, SUVpeak, and SULpeak were lower in 68Ga-FAPI-04 PET/CT than in 18F-FDG. 68Ga-FAPI-04 PET/CT showed a lower liver background and a higher TBRliver than 18F-FDG did. 68Ga-FAPI-04 PET/CT had higher accuracy, sensitivity, and specificity than 18F-FDG had. Conclusion: More accurate semiquantitative parameters and lower abdominal background in 68Ga-FAPI-04 PET/CT make it more competitive in the differential diagnosis of malignant and benign diseases than in 18F-FDG.

The interpretation of clinical oncologic PET studies has historically used static reconstructions based on SUVs. SUVs and SUV-based images have important limitations, including dependence on uptake times and reduced conspicuity of tracer-avid lesions in organs with high background uptake. The acquisition of dynamic PET images enables additional PET reconstructions via Patlak modeling, which assumes that a tracer is irreversibly trapped by tissues of interest. The resulting multiparametric PET images capture a tracer's net trapping rate and apparent volume of distribution, separating the contributions of bound and free tracer fractions to the PET signal captured in the SUV. Potential benefits of multiparametric PET include higher quantitative stability, superior lesion conspicuity, and greater accuracy for differentiating malignant and benign lesions. However, the imaging protocols necessary for multiparametric PET are inherently more complex and time intensive, despite the recent introduction of automated or semiautomated scanner-based reconstruction packages. In this Review, we examine the current state of multiparametric PET in whole-body oncologic imaging. We summarize the Patlak method and relevant tracer kinetics, discuss clinical workflows and protocol considerations, and highlight clinical challenges and opportunities. We aim to help oncologic imagers make informed decisions about whether to implement multiparametric PET in their clinical practices.

Neuroendocrine tumor (NET) metastases to the heart are found in 1%-4% of NET patients and have been reported primarily in the form of individual cases. We investigated the prevalence, clinical characteristics, imaging features, and outcomes of NET patients with cardiac metastases on 68Ga-DOTATATE PET/CT. Methods: 68Ga-DOTATATE PET/CT of 490 consecutive patients from a single institution were retrospectively reviewed for sites of metastases. The cumulative cardiovascular event rate and overall survival of patients with cardiac NET metastases (CNMs) were compared with those of a control group of metastatic NET patients without cardiac metastases. In patients with CNMs, the cardiac SUVmax with and without normalization to the myocardial background uptake was compared with a separate cohort of 11 patients with active cardiac sarcoidosis who underwent 68Ga-DOTATATE PET/CT for research purposes. Results: In total, 270 patients with metastatic NETs were identified, 9 (3.3%) of whom had CNMs. All 9 patients had grade 1-2 gastroenteropancreatic NETs, most commonly from the small intestine (7 patients). The control group consisted of 140 patients with metastatic grade 1-2 gastroenteropancreatic NETs. On Kaplan-Meier analysis, there was no significant difference in the risk of cardiovascular adverse events (P = 0.91 on log-rank test) or mortality (P = 0.83) between the metastatic NET patients with and without cardiac metastases. The degree of cardiac DOTATATE uptake was significantly higher in CNMs than in patients with cardiac sarcoidosis without overlap, in terms of both cardiac SUVmax (P = 0.027) and SUVmax-to-myocardial background ratio (P = 0.021). Conclusion: Routine 68Ga-DOTATATE PET/CT can be used to identify CNMs in 3% of patients with metastatic NETs. CNMs do not confer added cardiovascular or mortality risk. A distinguishing feature of CNMs is their high degree of DOTATATE uptake compared with focal myocardial inflammation.