Giant cell arteritis (GCA) is a difficult to diagnose large vessel vasculitis. CDUS, FDG-PET/CT and MRI are increasingly used for GCA diagnosis. This study aims to assess vascular wall lesions in GCA suspected patients, directly comparing CDUS, FDG-PET/CT and MRI with each other.

In a nested-case control study, consecutive GCA suspected patients were included. Scans were retrospectively assessed by two experts per imaging modality. Inter- and intraobserver agreement using Cohen's or Fleiss Kappa were calculated to assess agreement between experts, a few duplicated scans and between imaging modalities. Sensitivity and specificity of the imaging modalities for overall diagnostic performance and for individual arteries were calculated.

In total, 42 patients were included. Overall diagnostic performance of imaging modalities was comparable. Sensitivity and specificity were highest in the temporal artery for CDUS (76% and 93%; Kappa > 0.7) and MRI (60% and 100%; Kappa > 0.7), and in the vertebral (61% and 100%; Kappa 0.56) and maxillary artery (52% and 100%; Kappa 0.75) for FDG-PET/CT. Agreement between all modalities for a positive temporal artery was 0.76, but only 0.28 between CDUS and FDG-PET/CT. Agreement for the axillary artery was 0.7 between CDUS and FDG-PET/CT.

The temporal artery can be assessed by CDUS and MRI with good sensitivity and high specificity, and the axillary artery by CDUS and FDG-PET/CT with high agreement between the two modalities. In addition, the vertebral and maxillary artery can be assessed by FDG-PET/CT with good sensitivity and specificity, however the vertebral artery had moderate interobserver agreement.

Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has been established as a beneficial diagnostic tool in large vessel vasculitis. There have been limited studies of its use in real-world clinical practice. We examined patients at Royal Perth Hospital (RPH) with suspected giant cell arteritis (GCA) from January 2019 to 2022 who had 18F-FDG-PET/CT, and analysed its diagnostic accuracy compared to temporal artery biopsy (TAB) and clinical diagnosis at 6 months.

Patients referred to RPH Rheumatology with suspected GCA from January 2019 to 2022 were identified as having had 18F-FDG-PET/CT for diagnostic evaluation. 18F-FDG-PET/CT results were dichotomous into positive (consistent with GCA) or negative, and compared to TAB and clinical diagnosis of GCA at 6 months by a consultant rheumatologist.

A total of 32 patients had 18F-FDG-PET/CT for diagnostic purposes; nine of 32 18F-FDG-PET/CT scans were positive. Compared to TAB, 18F-FDG-PET/CT had a sensitivity of 50%, a specificity of 93%, a positive predictive value (PPV) of 86%, a negative predictive value (NPV) of 68% and accuracy of 61.5%. Compared to clinical diagnosis, 18F-FDG-PET/CT had a sensitivity of 41%, a specificity of 100%, a PPV of 100%, an NPV of 44% and accuracy of 59.4%. Only one 18F-FDG-PET/CT (11%) had cranial artery involvement. The median time taking glucocorticoids (GCs) was 7 days (interquartile range (IQR) 0-22.5 days) for positive 18F-FDG-PET/CT scans, versus 13 days (IQR 8-39 days) for negative 18F-FDG-PET/CT scans. The median time from request to scan was 29 days (IQR 31.5-77 days) for 18F-FDG-PET/CT on 14 or more days of GCs.

18F-FDG-PET/CT is more likely to be positive if it is performed within 7 days of steroid commencement. 18F-FDG-PET/CT had lower sensitivity and higher specificity than reported in clinical studies. In clinical practice, the significant delays from steroid start to scan time may reduce diagnostic sensitivity. A negative 18F-FDG-PET/CT scan did not negate the need for further investigations.

Nuclear medicine is rapidly evolving with new molecular imaging targets and advanced computational tools that promise to enhance diagnostic precision and personalized therapy. Recent years have seen a surge in novel PET and SPECT tracers, such as those targeting prostate-specific membrane antigen (PSMA) in prostate cancer, fibroblast activation protein (FAP) in tumor stroma, and tau protein in neurodegenerative disease. These tracers enable more specific visualization of disease processes compared to traditional agents, fitting into a broader shift toward precision imaging in oncology and neurology. In parallel, artificial intelligence (AI) and machine learning techniques are being integrated into tracer development and image analysis. AI-driven methods can accelerate radiopharmaceutical discovery, optimize pharmacokinetic properties, and assist in interpreting complex imaging datasets. This editorial provides an expanded overview of emerging imaging targets and techniques, including theranostic applications that pair diagnosis with radionuclide therapy, and examines how AI is augmenting nuclear medicine. We discuss the implications of these advancements within the field's historical trajectory and address the regulatory, manufacturing, and clinical challenges that must be navigated. Innovations in molecular targeting and AI are poised to transform nuclear medicine practice, enabling more personalized diagnostics and radiotheranostic strategies in the era of precision healthcare.

We aimed to develop and evaluate a novel computer-aided detection (CADe) approach for identifying small metastatic biochemically recurrent (BCR) prostate cancer (PCa) lesions on PSMA-PET images, utilizing multi-angle Maximum Intensity Projections (MA-MIPs) and state-of-the-art (SOTA) object detection algorithms.

We fine-tuned and evaluated 16 SOTA object detection algorithms (selected across four main categories of model types) applied to MA-MIPs as extracted from rotated 3D PSMA-PET volumes. Predicted 2D bounding boxes were back-projected to the original 3D space using the Ordered Subset Expectation Maximization (OSEM) algorithm. A fine-tuned Medical Segment-Anything Model (MedSAM) was then also used to segment the identified lesions within the bounding boxes.

The proposed method achieved a high detection performance for this difficult task, with the FreeAnchor model reaching an F1-score of 0.69 and a recall of 0.74. It outperformed several 3D methods in efficiency while maintaining comparable accuracy. Strong recall rates were observed for clinically relevant areas, such as local relapses (0.82) and bone metastases (0.80).

Our fully automated CADe tool shows promise in assisting physicians as a "second reader" for detecting small metastatic BCR PCa lesions on PSMA-PET images. By leveraging the strength and computational efficiency of 2D models while preserving 3D spatial information of the PSMA-PET volume, the proposed approach has the potential to improve detectability and reduce workload in cancer diagnosis and management.

A dysregulated immune response is involved in the pathogenesis of polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). These diseases have been reported as immune-related adverse events in patients with cancer treated with immune checkpoints inhibitors. In this cross-sectional study, the relationship between soluble immune checkpoint molecules (sICMs) and clinical/imaging features of PMR and GCA was investigated.

Consecutive patients with PMR diagnosed according to the criteria by Bird et al were compared with age- and sex-matched healthy controls. Patients with PMR and overlapping GCA had to also satisfy the 1990 ACR classification criteria for GCA. All patients underwent standardized clinical, laboratory examination, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography scans. The sICM anticytotoxic T Ly-4, the programmed cell death protein 1 (PD-1), and PD-1 ligands PD-L1 and PD-L2 were measured by enzyme-linked immunosorbent assay.

Forty patients (80% women, mean age 76 years, and mean disease duration 88 days) were assessed. Of these, 30 had isolated PMR and 10 had PMR with GCA. Patients showed significantly higher concentrations of all sICMs compared with controls (P < 0.001). Conditional logistic regression revealed the strong discriminative capacity of these molecules between patients and healthy controls, with PD-1 showing complete separation among groups (effect size = 0.78) and PD-L1 (odds ratio [OR] 134.33, P < 0.001) and PD-L2 (OR 63.00, P < 0.001) demonstrating the strongest ability to distinguish patients from controls. Correlations between sICM levels and clinical features were generally weak or absent, with no significant differences based on disease phenotype or glucocorticoid exposure. Results were similar in glucocorticoid-naive patients.

sICMs are significantly elevated in PMR and GCA and strongly differentiate patients from healthy controls. Although they do not correlate with clinical or imaging features, their consistent elevation in active disease might suggest a complex interplay between innate and adaptive immunity.

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.

There have been several case reports of COVID-19 "BNT162b2" (Pfizer-BioNTech) and "mRNA-1273" (Moderna) vaccination associated small and medium vessel vasculitis described in the literature however none have had 18F-FDG Positron Emission Tomography scans (PET/CT) performed for diagnosis. We report the case of a 57-year-old Caucasian male patient from Australia where 18F-FDG PET/CT scanning facilitated early detection of a medium-vessel vasculitis following Moderna (mRNA-1273) COVID-19 vaccination. The diagnosis would otherwise have been difficult and allowed exclusion of alternative diagnoses and sparing of more invasive investigations such as muscle biopsy. Our case highlights the development of a medium vessel vasculitis following mRNA based COVID-19 vaccination and demonstrates the utility of 18F-FDG PET/CT as an excellent non-invasive test for the detection of this serious rare and often difficult to diagnose condition.

The objective was to investigate the incidence of late-onset giant cell arteritis (GCA) within the first year in patients diagnosed with polymyalgia rheumatica (PMR).

In this prospective study, treatment-naïve individuals with a new clinical diagnosis of PMR and without GCA symptoms underwent baseline assessments, including vascular ultrasonography and 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography computed tomography (FDG-PET/CT). To prevent biased inclusion, rapid referral clinics were established for all patients suspected of PMR. Additionally, the patients underwent GCA monitoring during clinical visits at weeks 8 and 10, which involved vascular ultrasonography and FDG-PET/CT scans. After one year, a follow-up visit was performed to confirm the PMR diagnosis and perform vascular ultrasonography.

A final PMR diagnosis was assigned to 62 patients, excluding two patients with concurrent subclinical GCA and PMR at baseline, corresponding to a baseline prevalence of subclinical GCA of 3%. During the one-year follow-up, two PMR patients developed late-onset GCA corresponding to an incidence rate of 32 per 1000 person-years. One patient developed GCA 14 weeks after the PMR diagnosis, exhibiting cranial symptoms and positive vascular ultrasonography. The other patient presented with subclinical large vessel GCA at the one-year visit detected with vascular ultrasonography and confirmed by FDG-PET/CT.

This study is the first to demonstrate a low incidence rate of late-onset GCA in PMR patients within the first year, employing repeated imaging to exclude GCA at baseline and diagnose GCA during follow-up. Additionally, it provides evidence of a low prevalence of subclinical GCA across the entire PMR population.

ClinicalTrials.Gov, NCT04519580.

18F-FDG-PET/CT may reveal widespread inflammation of musculoskeletal structures in polymyalgia rheumatica (PMR). Currently, scans are subjectively analysed based on the overall gestalt of the scan. Standardized PET scores may potentially aid the interpretation of the scans for suspected PMR. Here, we compared the agreement and diagnostic accuracy of routine PET scan reports vs. the most validated PET scores for PMR.

68 consecutive patients with suspected PMR (treatment-naïve, n = 29; already treated, n = 39) undergoing 18F-FDG-PET/CT were included. In glucocorticoid-treated patients, complete tapering was pursued prior to the scan. Conclusions of routine PET scan reports were interpretated by three independent readers as "PMR", "not PMR" or "unclear". The Leuven and Leuven/Groningen scores were determined. Agreement of scan report interpretation, and agreement of routine scan reports and PET scores were determined. Sensitivity and specificity were determined for the routine scan report and the two scores, with the clinical diagnosis established after 6 months follow-up as the reference standard.

A diagnosis of PMR was made in 45/68 patients. Routine scan reports were uniformly rated by all three readers in 54 (78%) cases. Following a consensus meeting, scans were rated as "PMR" in 43 cases, "unclear" in 10 cases and "not PMR" in 15 cases. The routine scan report showed a sensitivity of 82% and specificity of 74%, if "unclear" cases were considered negative for PMR. The Leuven and Leuven/Groningen Scores showed similar diagnostic accuracy. Agreement between the routine scan report and PET scores was good (Cohen's kappa 0.60-0.64), if "unclear" cases were excluded from the analysis. Among 8/10 "unclear" cases, the PMR PET Scores accurately distinguished between PMR/PMR-mimicking inflammatory conditions and non-inflammatory conditions. Agreement and diagnostic accuracy of routine scan reports and PET scores were better among treatment-naïve patients than those that had been treated previously.

Our study reveals that routine PET scan reports for suspected PMR can be interpreted differently between readers. Although the routine PET scan reports and PMR PET scores did not always agree, they demonstrated similar diagnostic accuracy, with the highest accuracy observed in treatment-naive patients. The Leuven and Leuven/Groningen score could especially be helpful for cases in which the nuclear medicine physician is uncertain.

To study the changes in positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) aortic target-to-background ratio (TBR) and aortic calcification scores before and after 6 cycles of chemotherapy with the rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) regimen in patients with diffuse large B-cell lymphoma (DLBCL).

We selected 161 patients with DLBCL who received 6 cycles of R-CHOP standard chemotherapy and underwent baseline and 6-cycle efficacy evaluations using 18F-FDG PET/CT examinations at the Second Hospital of Dalian Medical University from July 2017 to June 2023. Additionally, 125 patients who underwent 18F-FDG PET/CT for physical examination during the same period, without active malignancy or systemic inflammatory disease, were chosen as the control group. We measured metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of systemic lymphoma lesions in tumor patients. Aortic wall FDG uptake was semi quantitatively analyzed as TBR (target-to-blood pool ratio) in five different vascular regions using oncological 18F-FDG PET/CT. The aortic TBR difference (ΔTBR) was the difference between the post- and pre-chemotherapy TBR values. The degree of arterial segmental wall calcification was assessed using the CT semiquantitative method.

Comparison of the pre-treatment group of DLBCL with the control group showed that aortic TBR (1.28 ± 0.17 vs. 1.22 ± 0.18, P < 0.05) were higher in the former group. Additionally, comparing different stage groups of patients with DLBCL revealed that aortic TBR (1.30 ± 0.18 vs. 1.22 ± 0.15, P < 0.05) were higher in the Stage III/IV group compared to the Stage I/II group. Aortic TBR was positively correlated with TLG (P = 0.016, R = 0.19) and MTV (P = 0.032, R = 0.17). Analysis of changes in aortic 18F-FDG uptake in patients with DLBCL after 6 cycles of treatment revealed that aortic TBR levels were significantly higher post-treatment compared to pre-treatment(P < 0.05). The aortic ΔTBR value was significantly higher in the progression group than in the complete remission group(P < 0.05).

Aortic wall 18F-FDG uptake is related to disease severity and prognosis, indicating a possible vascular effect of lymphoma and its therapeutic interventions. This work highlights an additional potential role of PET/CT in imaging oncology for evaluating disease severity and its consequences on the vasculature.

Objective  This study aims to investigate the correlation between the 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) activity of the liver and blood pool, and the serum albumin. Methods  A retrospective analysis was conducted on adult patients who underwent [ 18 F]FDG positron emission tomography/computed tomography at the Nuclear Medicine Unit of a hospital in Hong Kong between January 1, 2023, and March 31, 2023. The mean standardized uptake value normalized to lean body mass (SULmean) was measured in the liver and blood pool. Pearson's correlation analyses between the SULmean of reference regions and serum albumin were performed. Multiple linear regression was used to analyze the effects of serum albumin and other parameters as the independent predictors on SULmean of the reference regions. Results  A total of 146 patients were included, with their SULmean of the liver and blood pool showing significantly positive correlations with serum albumin ( r  = 0.393, p  < 0.001 and r  = 0.207, p  = 0.012, respectively). Multiple linear regression analyses confirmed serum albumin as an independent variable on SULmean of the liver and blood pool ( p  < 0.001 and p  = 0.014, respectively). Conclusion  Serum albumin alters [ 18 F]FDG biodistribution in the liver and blood pool. The decrease in liver background activity in patients with low serum albumin may produce a higher false-positive rate of lesion detection, particularly when there is a drop of serum albumin in serial scans. Nuclear medicine physicians should be cautious of image interpretation.

The diagnostic workup of primary lymphedema includes lymphoscintigraphy, a diagnostic test that provides objective data derived from the characteristics of the lymphatic flow and the lymphatic nodes. Several empirical scoring systems have been proposed with the aim of harmonizing the procedure. Here we comment the latest one, reflecting on the relevance of these tools to make possible multicenter research, based on intraobserver and interobserver reliability with the aim to, in the long run, improve patient outcomes.

Musculoskeletal disorders of nononcological origin are one of the most frequent reasons for consultation. Patients suffering from musculoskeletal disorders also consult more than once for the same reason. This results in multiple clinical follow-ups after several radiological and serum examinations, the main ones including X-rays targeting the painful anatomical region and inflammatory serum parameters. As part of their work up, patients suffering from musculoskeletal disorders often require multisequence, multi-parameter MRI. PET/MRI is a promising imaging modality for their diagnosis, with the added advantage of being able to be performed in a single visit. PET/MRI is particularly useful for diagnosing osteomyelitis, spondylodiscitis, arthritis, many pediatric pathologies, and a wide range of other musculoskeletal pathologies. PET/MRI is already used to diagnose malignant bone tumors such as osteosarcoma. However, current knowledge of the indications for PET/MRI in nononcological musculoskeletal disorders is based on studies involving only a few patients. This review focuses on the usefulness of PET/MRI for diagnosing nononcological musculoskeletal disorders.

This study directly compares the diagnostic performance of colour duplex ultrasound (CDUS), fluor-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI) in patients suspected of giant cell arteritis (GCA).

Patients with suspected GCA were included in a nested-case control pilot study. CDUS, whole body FDG-PET/CT and cranial MRI were performed within 5 working days after initial clinical evaluation. Clinical diagnosis after six months follow-up by experienced rheumatologists in the field of GCA, blinded for imaging, was used as reference standard. Diagnostic performance of the imaging modalities was determined. Stratification for GCA subtype was performed and imaging results were evaluated in different risk stratification groups.

In total, 23 patients with GCA and 19 patients suspected of but not diagnosed with GCA were included. Sensitivity was 69.6% (95%CI 50.4%-88.8%) for CDUS, 52.2% (95%CI 31.4%-73.0%) for FDG-PET/CT and 56.5% (95%CI 35.8%-77.2%) for MRI. Specificity was 100% for CDUS, FDG-PET/CT and MRI. FDG-PET/CT was negative for GCA in all isolated cranial GCA patients (n = 8), while MRI was negative in all isolated extracranial GCA patients (n = 4). In four GCA patients with false-negative (n = 2; intermediate and high risk) or inconclusive (n = 2; low and intermediate risk) CDUS results, further imaging confirmed diagnosis.

Sensitivity of CDUS was highest, while specificity was excellent in all imaging modalities. Nevertheless, confidence intervals of all imaging modalities were overlapping. Following EULAR recommendations, CDUS can be used as a first test to diagnose GCA. With insufficient evidence for GCA, further testing considering GCA subtype is warranted.

Fluorodeoxyglucose PET/computed tomography (FDG PET/CT) is effective in detecting large vessel vasculitis. Digital PET cameras have improved spatial resolution compared with analog PET, resulting in more prominent physiological uptake in arterial walls. This study's goal was to define qualitative normal variants of arterial activity on digital PET/CT.

We retrospectively reviewed 126 oncological PET/CT studies. Exclusion criteria included history of vasculitis, immunosuppressant therapy, hyperglycemia, or altered FDG biodistribution. Qualitative vessel wall activity (common carotid, brachiocephalic, subclavian, aorta, and femoral) was visually graded by two nuclear physicians with guideline-proposed criteria: 0: ≤mediastinum, 1: liver, where grade 3 is compatible, 2 is possible, and <2 is negative for vasculitis. Cranial artery uptake was visually graded as follows: grade 0: ≤surrounding tissues, grade 1: just above surrounding tissues, and grade 2: significantly above surrounding tissues, with grades 1 and 2 considered positive for cranial artery vasculitis.

Large vessel uptake was grade 3 in 0 subjects, grade 2 in four subjects (3%), grade 1 in 87 subjects (69%), and grade 0 in 35 subjects (28%). In studies acquired ≥75 min post-injection, 1/15 subjects had grade 2 uptake. Four subjects (3%) had grade 1 vertebral artery uptake. No subjects had temporal, maxillary, or occipital artery uptake.

A minority of our subjects presented with grade 2 large vessel uptake, which was associated with longer uptake times, or grade 1 cranial artery uptake, which was associated with higher age and glycemia. These findings should be interpreted with caution in patients referred for suspected vasculitis, as they may represent normal variants on digital PET.

Giant cell arteritis (GCA) is the most common of the large vessel vasculitides, with [18F] fluorodeoxyglucose (FDG) PET/CT indicated for evaluation of suspected large vessel involvement. Advances in PET/CT technology, particularly with digital PET, have significantly improved the assessment of cranial artery involvement in GCA. Recent guidelines have been updated to incorporate [18F]FDG PET/CT imaging in the diagnosis of GCA. This review article provides a practical guide to the most recent recommendations regarding PET/CT study indications, image acquisition and interpretation criteria for GCA, while discussing potential pitfalls and future research directions in the field.

[18F]Fluorodeoxyglucose (FDG) is widely used in PET/CT imaging to detect large vessel vasculitis in giant cell arteritis (GCA), but its performance is suboptimal in patients receiving glucocorticoids. We aimed to compare [68Ga]Ga-HA-DOTA-TATE, a somatostatin 2-analogue tracer, to [18F]FDG in a pilot study of patients with GCA.

Eight patients with active GCA were prospectively, sequentially scanned with both [18F]FDG PET/CT and [68Ga]Ga-HA-DOTA-TATE PET/CT imaging. Images were evaluated by 2 blinded nuclear medicine specialists. Tracer uptake was assessed in 8 vascular territories using SUVmax, and target-background ratios (TBR) were calculated using both right atrium (TBRRA) and liver mean (TBRliver). Mean SUVmax and TBR of individual vascular territories and index vessels were compared.

The patient median age was 71.5 years (range 64-82), and 4 (50%) were women. Active vasculitis (≥ grade 2 visual uptake in large vessels) was present in 62.5% of [18F]FDG scans. [18F]FDG scans had higher RA background activity than [68Ga]Ga-HA-DOTA-TATE (mean RA SUVmean 1.88 vs. 0.36, p < 0.001), while [68Ga]Ga-HA-DOTA-TATE had a significantly higher liver uptake (mean liver SUVmean 7.54 vs. 2.39, p < 0.001). Vascular uptake (as measured by both SUVmax and TBRliver) was significantly higher in [18F]FDG than [68Ga]Ga-HA-DOTA-TATE scans in every vascular territory (p < = 0.05 for all comparisons), including index vessels (SUVmax 4.04 vs. 1.91, p = 0.01, TBRliver 1.73 vs. 0.27, p < 0.001).

In this pilot study of patients with active GCA, the arterial uptake of [68Ga]Ga-HA-DOTA-TATE was lower and less conspicuous compared to [18F]FDG. While further evaluation in larger cohorts is needed, a clear advantage of [68Ga]Ga-HA-DOTA-TATE over [18F]FDG for detecting vascular inflammation in GCA was not identified. TRIAL REGISTRATION, CLINICALTRIALS.GOV: NCT03812302, registered 2019-01-18, URL: https://clinicaltrials.gov/search?cond=dotatate%20%26;term=giant%20cell%20arteritis .

To evaluate the diagnostic accuracy of PET/CT, cranial MRI, ultrasound and temporal artery biopsy (TAB) in patients with suspected giant cell arteritis (GCA) in a direct comparison.

Consecutive patients with a suspicion of GCA and at least 2 diagnostic tests ≤ 7 days after initiation of glucocorticoids between June 2021 and June 2024, were included retrospectively. The gold standard for the diagnosis of GCA was the judgment of experienced clinicians after a follow-up of ≥ 6 months. Examinations were compared within subgroups undergoing the same tests.

Sixty-one GCA patients and 50 patients with an alternative diagnosis were included. Combined cranial and large vessel PET/CT had the highest sensitivity (89% [95%CI 77-96%]) and specificity (98% [95%CI 88-100%]). Cranial PET/CT and TAB yielded a better sensitivity compared to temporal artery ultrasound (83% [95%CI 64-94%], 77% [95%CI 59-90%] and 55% [95%CI 36-74%], respectively, p = 0.023) without difference in specificity (100% [95%CI 100 - 84%], 95% [95%CI 76-100%] and 81% [95%CI 58-95%], respectively, p = 0.136). Cranial MRI had a sensitivity of 56% (95%CI 21-86%) and specificity of 82% (95%CI 48-98%). Large vessel PET/CT resulted in a better sensitivity compared to axillary artery ultrasound (68% [95%CI 45-86%] vs. 18% [95%CI 5-40%], p = 0.001) without difference in specificity (100% [95% CI 82-100%] vs. 90% [95%CI 67-99%], p = 0.50).

PET/CT had a better sensitivity than ultrasound and cranial MRI. TAB and cranial PET/CT had a similar diagnostic yield.

Not applicable.

Despite advancements in medical examination equipment and techniques, fever of unknown origin (FUO) remains challenging in internal medicine.

This study evaluates the diagnostic efficacy and necessity of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with FUO.

We retrospectively analyzed the results of 18F-FDG PET/CT in a cohort of 284 patients with FUO admitted to the Department of Infection at the First Hospital of Jilin University between January 2018 and March 2024. All patients received a final clinical diagnosis after various treatments, which helped determine the diagnostic relevance of identified lesions using 18F-FDG PET/CT. Additionally, univariate and multivariate logistic regression analyses were performed to evaluate the predictive value of relevant laboratory indices on the true-positive results of 18F-FDG PET/CT. The diagnostic performance for different etiologies of FUO was assessed by calculating the area under the receiver operating characteristic curve.

Of the 284 enrolled patients, infectious diseases were diagnosed in 53 (18.7%), non-infectious inflammatory diseases in 76 (26.8%), malignant tumors in 66 (23.2%), and 89 (31.3%) remained undiagnosed. The final diagnoses of 136 patients (47.9%) correlated with their 18F-FDG PET/CT results, yielding a sensitivity of 79.5%, specificity of 61.1%, positive predictive value of 75.6%, and negative predictive value of 66.3%. Furthermore, a correlation was found between localized pain, prolonged activated partial thromboplastin time, and true-positive 18F-FDG PET/CT results.

The high diagnostic efficacy of 18F-FDG PET/CT in FUO suggests its potential as a routine imaging modality, which could enhance patient management and reduce the need for costly and unnecessary invasive procedures. The identification of clinical factors that are predictive of true-positive diagnosis could facilitate more effective allocation of PET/CT imaging.

Objective: To investigate the feasibility of a machine learning (ML) model based on radiomic features to identify active giant cell arteritis (GCA) in the aorta and differentiate it from atherosclerosis in follow-up [18F]FDG-PET/CT images for therapy monitoring. Methods: To train the ML model, 64 [18F]FDG-PET scans of 34 patients with proven GCA and 34 control subjects with type 2 diabetes mellitus were retrospectively included. The aorta was delineated into the ascending, arch, descending, and abdominal aorta. From each segment, 95 features were extracted. All segments were randomly split into a training/validation (n = 192; 80%) and test set (n = 46; 20%). In total, 441 ML models were trained, using combinations of seven feature selection methods, seven classifiers, and nine different numbers of features. The performance was assessed by area under the curve (AUC). The best performing ML model was compared to the clinical report of nuclear medicine physicians in 19 follow-up scans (7 active GCA, 12 inactive GCA). For explainability, an occlusion map was created to illustrate the important regions of the aorta for the decision of the ML model. Results: The ten-feature model with ANOVA as the feature selector and random forest classifier demonstrated the highest performance (AUC = 0.92 ± 0.01). Compared with the clinical report, this model showed a higher PPV (0.83 vs. 0.80), NPV (0.85 vs. 0.79), and accuracy (0.84 vs. 0.79) in the detection of active GCA in follow-up scans. Conclusions: The current radiomics ML model was able to identify active GCA and differentiate GCA from atherosclerosis in follow-up [18F]FDG-PET/CT scans. This demonstrates the potential of the ML model as a monitoring tool in challenging [18F]FDG-PET scans of GCA patients.

Hybrid imaging consists of a combination of two or more imaging modalities, which equally contribute to image information. To date, hybrid cardiovascular imaging can be performed by either merging images acquired on different scanners, or with truly hybrid PET/CT and PET/MR scanners. The European Association of Nuclear Medicine (EANM), and the European Association of Cardiovascular Imaging (EACVI) of the European Society of Cardiology (ESC) aim to review clinical situations that may benefit from the use of hybrid cardiac imaging and provide advice on acquisition protocols providing the most relevant information to reach diagnosis in various clinical situations.

The role of fibroblast activation protein (FAP)-targeted imaging in systemic vasculitis is currently unclear. We aimed to evaluate the clinical value of fluorine-18-labeled FAP inhibitor 42 ([18F]FAPI-42) in patients with systemic vasculitis and to compare with [18F]fluorodeoxyglucose (FDG) imaging.

Patients with systemic vasculitis who underwent dual-tracer PET/CT([18F]FDG and [18F]FAPI) imaging from September 2020 to March 2022 were retrospectively analyzed. Positive lesions are defined as vascular/extravascular lesions with increased tracer uptake above surrounding background, which cannot be attributed to the physiologic biodistribution of the radiotracer. The vascular/extravascular lesion detection rate and semiquantitative values (SUVmax, TBRblood and TBRliver) of [18F]FAPI and [18F]FDG were compared, and the correlation between the extent and range of tracer uptake and levels of inflammatory markers was investigated.

Thirty patients (13 males and 17 females; mean age, 52.5 ± 17.2 years) with systemic vasculitis were included (17 large vessel vasculitis, 10 anti-neutrophil cytoplasmic antibody-associated vasculitis, 2 Behcet's disease and 1 polyarteritis nodosa). [18F]FDG PET/CT had positive findings in 93.3% (28/30) of patients, while [18F]FAPI PET/CT had positive findings in all patients (100%, P = 0.500). Compared with [18F]FDG PET/CT, [18F]FAPI PET/CT detected more lesions (161/168 vs. 145/168, P = 0.005), and more extensive vascular involvement in 60% (18/30) of patients. Although SUVmax did not differ significantly between [18F]FAPI and [18F]FDG (median, 5.94 vs. 5.46, P = 0.517), [18F]FAPI had higher TBRliver (median, 9.59 vs. 3.15, P < 0.001) and TBRblood (median, 5.45 vs. 4.20, P = 0.006). The total number of positive lesions in FAPI PET/CT show a moderate correlation with erythrocyte sedimentation rate (rs =0.478, P = 0.008) and C-reactive protein (rs =0.486, P = 0.006). After treatment, follow-up FAPI PET/CT of 6 patients showed decreased SUVmax, TBR and number of detected lesions, paralleling the clinical remission.

[18F]FAPI PET/CT imaging is a promising imaging modality for the diagnosis and therapeutic monitoring of systemic vasculitis.

The objective of this study was to assess the value of 18F-fluorodeoxyglucose (FDG)- positron emission tomography (PET) scans to monitor disease activity in patients with giant cell arteritis (GCA) on tocilizumab.

Patients with GCA were recruited into a prospective cohort in which they underwent clinical, laboratory, and imaging assessments, including FDG-PET. FDG-PET scans were interpreted as active or inactive based on global impression by two independent readers. The PET Vascular Activity Score (PETVAS) was calculated to quantify arterial FDG uptake (scale 0-27). Vascular FDG-PET findings were described in patients with GCA on tocilizumab for at least six months. For patients in established clinical remission, FDG-PET findings were compared between those treated with tocilizumab versus glucocorticoid monotherapy.

A total of 36 patients with GCA underwent FDG-PET imaging on tocilizumab. Five patients had active clinical symptoms, and FDG-PET scans were active in all cases (PETVAS range: 20-27). For the 31 patients in clinical remission on tocilizumab, FDG-PET was active in 16 of these patients (52%) across a wide range of PETVAS (range 11-27). There were no associations between FDG-PET activity during remission and historical clinical features or longitudinal outcomes, including relapse risk or angiographic progression of disease. PETVAS was significantly lower during clinical remission in patients treated with tocilizumab compared to an additional 12 patients treated with glucocorticoid monotherapy (PETVAS 18 vs 24; P = 0.02).

FDG-PET has limited value to guide management decisions or inform prognosis when obtained during remission in patients with GCA on tocilizumab. Compared to glucocorticoid monotherapy, tocilizumab significantly reduces, but often does not eliminate, vascular inflammation in GCA.

To investigate the proportion and distribution of contrast enhancement (CE) of musculoskeletal structures with MRI of the thorax/abdomen/pelvis in giant cell arteritis (GCA).

CE at 34 musculoskeletal sites was rated with a four-point ordinal scale. Patients were divided into groups with or without glucocorticoid (GC) treatment and with or without symptoms of polymyalgia rheumatica (PMR). Two composite scores were created: an MRI score, including seven sites, and a limited MRI score, including four sites.

Retrospectively, 90 consecutive patients with GCA were included. The population included 54 and 36 patients with and without PMR symptoms, respectively, and 45 (50%) patients were receiving GCs at the time of MRI. CE was found in 90.7% of lumbar spines, 87.5% of the pelvis, 82.2% of shoulder girdles and in 95.6% at any site in patients without GCs. The proportion of patients without and with GCs with at least moderate enhancement was, respectively, 91.1% and 75.6% at ≥1-3 sites, 75.6% and 51.1% at ≥4-6 sites, and 64.4% and 28.9% at ≥7-9 sites. The mean difference between the proportion of pathological CE in patients with and without GCs was 27.4% for synovial sites and 18.3% for periarticular/musculotendinous sites. Both composite scores captured substantial differences between groups, and correlation was very strong between scores.

MRI shows CE of musculoskeletal structures typical of PMR in most patients with GCA, supporting the concept of 'GCA-PMR spectrum disease'. Changes are more frequent at periarticular/musculotendinous sites and in the presence of PMR symptoms. A clear response to GCs is evident, less so for periarticular/musculotendinous sites.

Hybrid [18F]FDG PET imaging is currently the method of choice for a wide variety of infectious and inflammatory disorders and was recently adopted in several clinical guidelines. A large amount of evidence-based articles, guidelines and appropriate use criteria have been published since the first version of this guideline in 2013.

To provide updated evidence-based information to assist physicians in recommending, performing and interpreting hybrid [18F]FDG PET examinations for infectious and inflammatory disorders in the adult population.

A systematic literature search of evidence-based articles using whole-body [18F]FDG hybrid imaging on the indications covered within this guideline was performed. All systematic reviews and meta-analyses published within the last 10 years until January 2023 were identified in PubMed/Medline or Cochrane. For each indication covered in this manuscript, diagnostic performance was provided based on meta-analyses or systematic reviews. If not available, results from prospective or retrospective studies were considered based on predefined selection criteria. RESULTS AND CONCLUSIONS: Hybrid [18F]FDG PET is extremely useful in the work-up and management of adults with infectious and inflammatory diseases, as supported by extensive and rapidly growing evidence-based literature and adoption in clinical guidelines. Practical recommendations are provided describing evidence-based indications as well as interpretation criteria and pitfalls. Monitoring treatment response is the most challenging but insufficiently studied potential application in infection and inflammation imaging.

Vascular inflammation persists in temporal artery biopsy (TAB) of giant cell arteritis (GCA) patients even after prolonged glucocorticoid (GC) therapy. We aimed to evaluate the histological impact of adding tocilizumab (TCZ) to GCs.

We enrolled all consecutive GCA patients with an inflammed TAB at diagnosis who were treated with TCZ and GCs for ≥6 months and followed from December 2017 to December 2023. Within 2 weeks, all patients underwent a second TAB, positron emission 18-fluorodeoxyglucose tomography/CT (PET/CT) and vessel colour Doppler ultrasonography (CDUS). Results were compared with pretreatment findings.

13 patients repeated TAB after a median TCZ treatment of 2.4 years (Q1-Q3: 1.2-3.9 years). The first TAB showed transmural inflammation (TMI) in 11/13 patients (84.6%), inflammation limited to adventitia (ILA) in one patient (7.7%) and small vessel vasculitis (SVV) in another (7.7%). On repeated TABs, five patients (38.5%) still showed some degree of inflammation. Among the 11 patients with initial TMI, 2 had ILA, 1 had TMI, 1had SVV and 1 had vasa vasorum vasculitis at the second TAB. Nine patients had active vasculitis at baseline PET/CT, and three (33.3%) still showed activity at the last PET/CT, with a relevant reduction in mean PET vascular activity score (-6.5; 95% CI 1.54 to 11.45; p=0.017). The repeated quantitative CDUS revealed altered parameters suggestive of vasculitis in temporal arteries in about one-third of the patients.

Our study, using pathological and imaging assessments, revealed that after TCZ and GCs, over one-third of patients still presented with vascular inflammation.

To investigate differences in arterial involvement patterns on 18F-FDG PET-CT between predominant cranial and isolated extracranial phenotypes of giant cell arteritis (GCA).

A retrospective review of 18F-FDG PET-CT findings was conducted on 140 patients with confirmed GCA. The patients were divided into two groups: the cranial group, which presented craniofacial ischemic symptoms either at diagnosis or during follow-up, and the isolated extracranial group which never exhibited such manifestations.

Of the 140 patients (90 women), 99 (71%) were considered to have a predominantly cranial phenotype, while 41 (29%) had isolated extracranial GCA. Patients with the extracranial phenotype were younger (p = 0.001), had lower TAB positivity (25%), and experienced longer diagnostic delays (p = 0.004). Polymyalgia rheumatica was more common in the extracranial group (p = 0.029), which also showed fewer constitutional symptoms, milder increases in acute phase reactants, and more frequent limb claudication and aortic complications, although these differences were not statistically significant. When comparing arterial involvement on 18F-FDG PET-CT, we observed statistically significant differences. The extracranial phenotype showed greater involvement across all segments of the thoracic aorta (p = 0.001), as well as in the abdominal aorta (p = 0.005), subclavian (p = 0.021), iliac (p = 0.004), and femoral arteries (p = 0.025). In contrast, the cranial phenotype exhibited a higher frequency of vertebral artery involvement (p < 0.001).

Significant differences in arterial involvement patterns on 18F-FDG PET-CT were observed between phenotypes. These findings may explain atypical symptoms such as inflammatory lower back pain or limb claudication and the increased risk of aortic complications in extracranial GCA.

Giant cell arteritis (GCA) is the most common vasculitis in patients older than 50 years and is considered a "do not miss" diagnosis. However, it remains a diagnostic challenge given overlapping clinical syndromes such as non-arteritic anterior ischemic optic neuropathy (NAION) and poorly explored imaging findings.

In this retrospective study between the time period of January 2013 and December 2021, a total of 13 consecutive patients with a pathological diagnosis of GCA and 8 patients with clinical diagnosis of NAION were isolated. Demographic and clinical data for each patient were collected, including pertinent laboratory data. Pertinent physical exam data was also collected, including fundoscopic exam and visual acuity. Two neuroradiologist assessed the orbital MRI imaging findings of GCA and NAION for the presence and characterization of imaging abnormalities. Assessment for potential relationship between GCA orbital findings, laboratory and visual outcomes was performed. Finally, comparison between GCA and NAION imaging findings was performed.

13 GCA patients were assessed. 9 patients had abnormal orbital findings. Of these 8 patients had bilateral orbital involvement The most common imaging findings was perineuritis of the optic nerve sheath, present in 7 patients. In total, 8 NAION patients were assessed. All patients demonstrate optic nerve involvement. The Snellen test was converted to logmar, and visual acuity was assessed for both NAION and GCA for each eye at diagnosis and at the last follow-up. There was no statistical significance for either eye for both GCA and NAION at initial diagnosis and final follow-up. In the 4 GCA patients with normal MRI findings and 9 GCA patients with abnormal MRI findings, there was no statistical significance between initial presentation and final follow-up visual acuity.

GCA and NAION are potentially overlapping clinical syndromes with different treatment approach and poorly explored imaging findings. Our case series assesses the orbital imaging findings of both syndromes while noting different imaging pattern of both on MRI, which can serve as a potential tool to aid in diagnosis of both. .

This study aimed to evaluate the diagnostic utility of [68Ga]Ga-DOTA-Siglec-9 positron emission tomography-computed tomography (PET/CT) in assessing disease activity in a patient experiencing a relapse of giant cell arteritis (GCA).

A 90-year-old male patient with GCA, diagnosed in 2018, was enrolled. Demographic data, disease history, and laboratory parameters, including soluble VAP-1 (sVAP-1) levels, were recorded. The patient underwent a [68Ga]Ga-DOTA-Siglec-9 PET/CT scan. Additional imaging assessments included vascular ultrasound of the superficial temporal arteries, their branches, and the facial, axillary, subclavian, carotid, and vertebral arteries, along with magnetic resonance imaging (MRI) of the aorta.The patient's sVAP-1 level was 284 ng/ml compared to 123 ng/ml in the control group (SD ± 55). The [68Ga]Ga-DOTA-Siglec-9 PET/CT scan revealed increased tracer uptake (SUVmax) in the subclavian artery (2.5), aortic arch (2.9), and heart (2.9). Notably, the increased uptake in the descending aorta (3.5) abruptly diminished to 2.2 when passing the diaphragm, with no changes in vessel caliber observed in CT. The injection of [68Ga]Ga-DOTA-Siglec-9 was well tolerated. Aortic MRI revealed no signs of inflammatory involvement.

This study introduces the first application of [68Ga]Ga-DOTA-Siglec-9 PET/CT in a patient with GCA experiencing a relapse, revealing enhanced tracer uptake in the subclavian artery and aortic arch with a localized and abrupt reduction, absent in conventional imaging. These findings suggest that [68Ga]Ga-DOTA-Siglec-9 PET/CT has significant potential for precise, inflammation-specific detection of affected vascular tissue in GCA during relapse.

Reactive oxygen species (ROS) are generated predominantly during cellular respiration and play a significant role in signaling within the cell and between cells. However, excessive accumulation of ROS can lead to cellular dysfunction, disease progression, and apoptosis that can lead to organ dysfunction. To overcome the short half-life of ROS and the relatively small amount produced, various imaging methods have been developed, using both endogenous and exogenous means to monitor ROS in disease settings. In this review, we discuss the molecular mechanisms underlying ROS production and explore the methods and materials that could be used to detect ROS overproduction, including iron-based materials, ROS-responsive chemical bond containing polymers, and ROS-responsive molecule containing biomaterials. We also discuss various imaging and imaging techniques that could be used to target and detect ROS overproduction. We discuss the ROS imaging potentials of established clinical imaging methods, such as magnetic resonance imaging (MRI), sonographic imaging, and fluorescence imaging. ROS imaging potentials of other imaging methods, such as photoacoustic imaging (PAI) and Raman imaging (RI) that are currently in preclinical stage are also discussed. Finally, this paper focuses on various diseases that are associated with ROS overproduction, and the current and the future clinical applications of ROS-targeted imaging. While the most widely used clinical condition is cardiovascular diseases, its potential extends into non-cardiovascular clinical conditions, such as neurovascular, neurodegenerative, and other ROS-associated conditions, such as cancers, skin aging, acute kidney injury, and inflammatory arthritis.

Large vessel vasculitides (LVV) such as giant cell arteritis, Takayasu arteritis and aortitis/periaortitis are characterised by immune-mediated inflammation of medium to large arteries. Clinical disease manifestations can be non-specific and diagnostic imaging plays an important role in the diagnostic pathway. In recent years, FDG PET/CT has proven to be a powerful metabolic tool that can provide a wholed body, non-invasive assessment of vascular inflammation. This review outlines the clinical features of large vessel vasculitis and the closely related entity of polymyalgia rheumatica, summarises the evidence for FDG PET/CT in the assessment of these conditions, and provides guidance for patient preparation, image acquisition and interpretation.

Late-stage eosinophilic myocarditis (or Löffler endocarditis) is known to occur in patients with hypereosinophilic syndrome and can cause restrictive cardiomyopathy. Eosinophilic myocarditis is an acute life-threatening inflammatory disease of the heart that can be associated with cancer. We report a case of a 70-year-old White woman, previously treated for diffuse large B-cell lymphoma in remission, admitted for acute dyspnea with a 1-year history of hypereosinophilia. 18F-FDG PET/CT revealed endocardial uptake consistent with MRI gadolinium enhancement, suggesting left ventricular wall inflammation.

Giant cell arteritis (GCA) is an autoimmune/autoinflammatory disease affecting large vessels in patients over 50 years old. The disease presents as an acute inflammatory response with two phenotypes, cranial GCA and large-vessel vasculitis (LV)-GCA, involving the thoracic aorta and its branches. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT) is among the imaging techniques contributing to diagnosing patients with systemic disease. However, its association with soluble inflammatory markers is still elusive. This proof-of-concept study aims to identify novel soluble serum biomarkers in PET/CT-positive patients with LV-GCA and associate them with active (0 months) and inactive disease (6 months following treatment), in sequential samples. The most-diseased-segment target-to-background ratio (TBRMDS) was calculated for 13 LV-GCA patients, while 14 cranial GCA and 14 Polymyalgia Rheumatica patients with negative initial PET/CT scans served as disease controls. Serum macrophage-related cytokines were evaluated by cytometric bead array (CBA). Finally, previously published NMR/metabolomics data acquired from the same blood sampling were analyzed along with PET/CT findings. TBRMDS was significantly increased in active versus inactive disease (3.32 vs. 2.65, p = 0.006). The analysis identified nine serum metabolites as more sensitive to change from the active to inactive state. Among them, choline levels were exclusively altered in the LV-GCA group but not in the disease controls. Cytokine levels were not associated with PET/CT activity. Combining CRP, ESR, and TBRMDS with choline levels, a composite index was generated to distinguish active and inactive LV-GCA (20.4 vs. 11.62, p = 0.001). These preliminary results could pave the way for more extensive studies integrating serum metabolomic parameters with PET/CT imaging data to extract sensitive composite disease indexes useful for everyday clinical practice.

Large vessel vasculitides (LVV) comprise a group of inflammatory disorders that involve the large arteries, such as the aorta and its primary branches. The cause of LVV is often rheumatologic and includes giant cell arteritis and Takayasu arteritis. Giant cell arteritis is the most common form of LVV affecting people >50 years of age with a slight female predominance. Takayasu arteritis is more frequently seen in younger populations and is significantly more common in women. Prompt identification of LVV is crucial as it can lead to debilitating complications if left untreated, including blindness in the case of giant cell arteritis and large artery stenosis and aneurysms in the case of all forms of LVV. Noninvasive imaging methods have greatly changed the approach to managing LVV. Today, imaging (with ultrasound, magnetic resonance imaging, computed tomography, and positron emission tomography) is routinely used in the diagnosis of LVV. In patients with giant cell arteritis, imaging often spares the use of invasive procedures such as temporal artery biopsy. In addition, vascular imaging is also crucial for longitudinal surveillance of arterial damage. Finally, imaging is currently being studied for its role in assessing treatment response and ongoing disease activity and its potential value in determining the presence of vascular wall remodeling (eg, scarring). This review explores the current uses of noninvasive vascular imaging in LVV.

Vascular imaging is an integral part of large-vessel vasculitis (LVV) evaluation and management. Several imaging modalities are currently employed in clinical practice including vascular ultrasound, computed tomography angiography, MRI and magnetic resonance angiography, and 18F-fluorodeoxyglucose PET. Well-established roles for imaging in LVV include disease diagnosis and assessment of luminal lesions reflecting vascular damage. The ability of imaging to determine treatment response, monitor disease activity, and predict future arterial damage is an area of active research.

Sodium Fluoride-18 production started in the 1940s and was described clinically for the first time in 1962 as a bone-imaging agent. However, its use became dormant with the development of conventional bone scintigraphy, especially due to its low cost. Conventional bone scintigraphy has been the most utilized Nuclear Medicine technique for identifying osteoblastic bone metastases, especially in prostate and breast cancers for decades and is also employed to identify benign bone disease, especially in the orthopedic setting. While bone scintigraphy is highly sensitive, it lacks adequate specificity. With the advent of high-quality 3D Whole-Body Positron Emission Tomography combined with computed tomography (PET/CT), images, Sodium Fluoride-18 imaging with PET/CT (Fluoride PET/CT) re-emerged. This PET/CT bone-imaging agent provides higher sensitivity and specificity to detect bone lesions in both the oncological scenario as well as to identify benign bone and joint disorders. PET/CT bone-imaging provides a precise view of the bone metabolism remodeling processes at a molecular level, throughout the skeleton, and combines anatomical information, enhancing diagnostic specificity and accuracy. This article review will explore the updates on clinical applications of Fluoride PET/CT in oncology and benign conditions encompassing orthopedic, inflammatory and cardiovascular conditions and treatment response assessment.

Background/Objectives: Imaging studies have transformed the diagnosis of large vessel vasculitis (LVV) involvement in giant cell arteritis (GCA). A positron emission tomography/computed tomography (PET/CT) scan with 18-fluorodeoxyglucose (18F-FDG) has emerged as a valuable tool for assessing LVV. We aimed to determine the utility of an 18F-FDG-PET/CT scan in detecting LVV in GCA in the ARTESER registry. Methods: The ARTESER study is a large multicenter, retrospective, longitudinal, and observational study, promoted by the Spanish Society of Rheumatology. It included patients newly diagnosed with GCA across 26 tertiary hospitals from 1 June 2013 to 29 March 2019. Patients with a diagnosis of incidental GCA were included if they fulfilled specific criteria, including the ACR 1990 criteria, positive imaging examinations, or the expert clinical opinion of investigators. Differences between patients with positive and negative 18F-FDG-PET/CT scan results were analyzed using a bivariate model. A regression model assessed associations in patients with a positive scan, and the predictive capacity of the cumulative dose of glucocorticoids (GC) on PET scan outcomes was evaluated using ROC curve analysis. Results: Out of 1675 GCA patients included in the registry, 377 met the inclusion criteria of having an 18F-FDG-PET/CT scan. The majority were diagnosed with a cranial GCA phenotype, and 65% had LVV. The thoracic aorta was the most frequently affected. Cardiovascular disease, diabetes, and older age had a negative association with a positive scan outcome. The OR for having a positive 18F-FDG-PET/CTC scan was lower as the number of days increased. Depending on the cumulative dosage of the GC, the 18F-FDG-PET/CT scan showed an AUC of 0.74, with a Youden index > 60 mg/day. Conclusions: Younger patients showed a higher probability of presenting LVV as detected by the 18F-FDG-PET/CT scan. The timing of the examination and the cumulative dosage of the GC influenced the likelihood of a positive result, with earlier tests being more likely to detect inflammation.