• Magnetic resonance imaging
• rectal cancer
• stage

• MRI
• anal
• cancer
• neoplasms
• perianal

• magnetic resonance imaging
• rectal cancer
• staging

• Humans
• Magnetic Resonance Imaging/methods
• Neoplasm Staging
• Rectal Neoplasms/diagnostic imaging
• Rectal Neoplasms/pathology

• MRI
• chemoradiotherapy
• locally advanced
• mucinous rectal cancer
• neoadjuvant treatment
• rectal cancer
• response evaluation

Purpose: Mucinous adenocarcinoma (MA) is associated with worse clinicopathological characteristics and a poorer prognosis than non-MA. Moreover, MA is related to worse tumor regression grade and tumor downstaging than non-MA. This study investigated whether lesions in MA and non-MA can be quantitatively assessed by T2 mapping technique and compared with the diffusion-weighted imaging (DWI).

Methods: High-resolution MRI, DWI, and T2 mapping were performed on 81 patients diagnosed with rectal cancer via biopsy. Afterward, T2 and apparent diffusion coefficient (ADC) values were manually measured by a senior and a junior radiologist independently. By examining surgical specimens, the patients with MA and non-MA were identified. Inter-observer reproducibility was tested, and T2 and ADC values were compared using Mann–Whitney U test. Finally, receiver operating characteristic (ROC) curves were drawn to determine the cut-off value.

Results: Of the 81 patients, 11 patients with MA were confirmed by pathology. The inter-observer reproducibility of T2 and ADC values showed an excellent intraclass correlation coefficient (ICC) of 0.993 and 0.913, respectively. MA had higher T2 (87.9 ± 5.11 ms) (P = 0.000) and ADC (2.03 × 10⁻³ mm²/s) (P = 0.000) values than non-MA (66.6 ± 6.86 ms and 1.17 × 10⁻³ mm²/s, respectively). The area under the ROC curves (AUC) of the T2 and ADC values were 0.999 (95% confidence interval [CI]: 0.953–1) and 0.979 (95% CI: 0.920–0.998), respectively. When the cutoff value in T2 mapping was 80 ms, the Youden index was the largest, sensitivity was 100%, and specificity was 97%.

Conclusion: As a stable quantitative sequence, T2 mapping of MRI is useful in differentiating MA from non-MA. Compared to ADC values, T2 values are also diagnostically effective and non-inferior to ADC values.

• T2 mapping
• diffusion-weighted imaging
• magnetic resonance imaging
• mucinous adenocarcinoma
• rectal cancer

• Magnetic resonance imaging
• Mucins
• Neoadjuvant therapy
• Rectal neoplasms

Background and Aim: This work aims to study the relationship between MRI-defined mucin pool (MP) patterns prior to treatment and the efficacy of neoadjuvant therapy (NAT) in locally advanced rectal mucinous adenocarcinoma (RMAC).

Methods: This retrospective study included 278 RMAC patients evaluated between January 2012 and January 2019. After having been trained by using 118 cases with postoperative pathological images, radiologists distinguished MRI-defined MP status as mixed type (MTMP) and separate type (STMP) in a NAT cohort (160 patients) in addition to tumor characteristics, invasion of mesorectal facia, and nodal status. Reader reproducibility was determined using the κ coefficient. The main outcome was the accuracy of MP dichotomy in predicting whether patients had tumor responsiveness or not.

Results: Among 278 cases, MTMP and STMP accounted for 49.6 and 50.4% of MPs, respectively. A total of 72 patients received neoadjuvant chemoradiotherapy and 88 received chemotherapy. The tumor responsiveness rate in the chemoradiotherapy group was higher than that in the chemotherapy group (58.3 vs. 21.6%, P < 0.001). In the chemotherapy group, the tumor responsiveness rate in patients with MTMPs was lower than that in patients with STMPs (4.9 vs. 25.5%, P = 0.002). The baseline MRI-defined MTMP was associated with lower responsiveness rates after NAT in the chemotherapy group (odds ratio, 11.050, with 95% CI, 2.368–51.571, P = 0.002).

Conclusions: MP dichotomy can be reliably evaluated by using MRI. In the chemotherapy group, MTMP may be a dependent predictor to indicate a lower likelihood of tumor responsiveness after NAT.

• magnetic resonance imaging
• mucins
• neoadjuvant therapy
• rectal neoplasms
• treatment outcome

• CT
• Rectal cancer
• mucinous adenocarcinoma
• radiomics

• Adenocarcinoma/diagnostic imaging
• Adenocarcinoma, Mucinous/diagnostic imaging
• Cohort Studies
• Diagnosis, Differential
• Female
• Humans
• Male
• Middle Aged
• Rectal Neoplasms/diagnostic imaging
• Rectum/diagnostic imaging
• Retrospective Studies
• Tomography, X-Ray Computed/methods

• KRAS mutation
• Magnetic resonance imaging
• Rectal cancer
• Texture

• Computed tomography
• Magnetic resonance imaging
• Mucin
• Positron emission tomography
• Rectal neoplasms

• Computed tomography
• Magnetic resonance imaging
• Mucin
• Positron emission tomography
• Rectal neoplasms

• Adenocarcinoma, Mucinous/diagnostic imaging
• Adenocarcinoma, Mucinous/pathology
• Adenocarcinoma, Mucinous/therapy
• Chemoradiotherapy
• Humans
• Neoadjuvant Therapy
• Neoplasm Staging
• Rectal Neoplasms/diagnostic imaging
• Rectal Neoplasms/pathology
• Rectal Neoplasms/therapy

• P30 CA008748 NCI NIH HHS

• Anal cancer
• Cancer imaging
• Low rectal cancer
• MRI

• Anal Canal/diagnostic imaging
• Anus Neoplasms/diagnostic imaging
• Diagnosis, Differential
• Female
• Humans
• Magnetic Resonance Imaging/methods
• Male
• Middle Aged
• Rectal Neoplasms/diagnostic imaging
• Rectum/diagnostic imaging
• Retrospective Studies
• Sensitivity and Specificity

The purpose of this study was to evaluate treatment response to neoadjuvant chemoradiotherapy (CRT) with regard to mucin status in pathology and pretreatment magnetic resonance imaging (MRI) in locally advanced rectal cancer.

Between 2003 and 2011, 306 patients with locally advanced rectal cancer received neoadjuvant CRT followed by surgery, and mucinous adenocarcinoma (MAC) was found in 27 (8.8%). All MAC patients had MRI before and after CRT and mucin proportion at MRI was measured. Therapeutic response was assessed by pathology after total mesorectal excision. To determine the optimal cut-off for mucin proportion in predicting good CRT response (near total or total regression) and negative circumferential resection margin (CRM), the receiver-operating characteristic analysis was performed.

After neoadjuvant CRT, overall downstaging occurred in 44.4% of MAC and 72.4% of non-MAC (p=0.001), and positive CRM (≤1 mm) was observed more frequently in MAC (p<0.001). The optimal threshold for treatment response was 30% for mucin proportion, and there are nine with low mucin proportion (<30%) and 18 with high mucin proportion (≥30%) in pretreatment MRI. Negative CRM and tumor downstaging occurred more common in patients with mucin <30%, although statistically insignificant (p=0.071 and p=0.072, respectively). Regarding oncologic outcomes, lower mucin proportion in pretreatment MRI was associated with better disease-free and overall survival in MAC group (p=0.092 and 0.056, respectively), but the difference did not reach statistical significance.

Poor treatment outcome with neoadjuvant CRT was observed in patients with MAC, especially those with high mucin proportion at pretreatment MRI.

• Magnetic resonance imaging
• Mucinous rectal cancer
• Neoadjuvant chemoradiotherapy

• Chemoradiotherapy
• Mucin pool
• Mucinous carcinoma
• Pathological response
• Rectal cancer
• Tumor shrinkage

Most colorectal cancers are classical adenocarcinomas (AC), and less frequent subtypes include mucinous adenocarcinomas (MAC) and signet-ring cell carcinomas (SC). The purpose of this study was to evaluate the computed tomography (CT) findings that can help to differentiate MAC and SC from AC.

CT scans of 168 patients with pathologically proven MAC and 67 patients with pathologically proven SC were analyzed, and 220 patients with classical AC were also included as a control group. CT findings of the three groups were compared and contrasted in terms of the bowel involvement patterns, contrast enhancement patterns, and presence or absence of bowel obstruction, intratumoral calcification, pericolic fat infiltration, and local tumor extension to adjacent organs. Statistical analyses were made by using the one-way analysis of variance, least significant difference test, and Pearson’s chi-square test.

Compared with classical AC, the MAC showed more severe (6.29±2.69 cm vs 4.57±1.74 cm, P<0.001) and higher percentage of occurrence of eccentric bowel-wall thickening (37.2% vs 11.5%, P<0.001). Heterogeneous contrast enhancement was most common in MAC (P<0.01), and MAC showed more areas with hypoattenuation (P<0.001). The presence of intratumoral calcification was most frequent in MAC (17.9% vs 2% vs 6.8%) (P<0.001); the SC also were more severe (5.75±2.28 cm vs 4.57±1.74 cm. P=0.001) than AC, but SC tend to show more cases of concentric even bowel-wall thickening (67.2%); homogeneous contrast enhancement was most common in SC (P<0.01), and it showed a target appearance. The presence of peritoneal seeding was most frequent in SC (35.8% vs 8% vs 2.7%, P<0.001), while the presence of regional lymph node metastasis (P=0.190) and direct invasion of adjacent organs or metastasis (P=0.323) were not significantly different among them.

Some radiological features by CT can be used to classify different colon tumor types.

• cancer
• colorectal
• computed tomography
• mucinous
• prognosis
• signet ring

• MRI
• chemoradiation therapy
• rectal cancer
• recurrence
• staging

• Focal nodular hyperplasia
• Hepatic adenoma
• Hepatic steatosis
• Hepatocellular carcinoma
• Magnetic resonance imaging
• Siderotic regenerative nodules

Endorectal ultrasonography (ERUS) and magnetic resonance imaging (MRI) allow exploring the morphology of the rectum in detail. Use of such data, especially assessment of the rectal wall, is an important tool for ascertaining the perianal fistula localization as well as stage of the cancer and planning it appropriate treatment, as stage T3 tumors are usually treated with neoadjuvant therapy, whereas T2 tumors are initially managed surgically. The only advantage of ERUS over MRI is the possibility of assessing T1 tumors that could be treated by transanal endoscopic microsurgery. However, MRI is better for visualizing most radiological prognostic features in rectal or anal cancer such as a circumferential resection margin less than 1 mm, T stage at T1-T2 or T3 tumors with extramural extension less than 5 mm, absence of extramural vascular invasion, N stage at N0/N1, and tumors located in the middle or upper third of the rectum. It can also evaluate the intersphincteric space or levator ani muscle involvement. Increased signal on diffusion weighted imaging (DWI) and low apparent diffusion coefficient (ADC) values as well as an irregular contour and heterogeneous internal signal intensity seem to predict the involvement of pelvic lymphatic nodes better than their size alone. Computed tomography as well as other examination techniques, including digital rectal examination, contrast edema, recto- and colonoscopy, are less useful in staging of rectal cancer but still are very important screening tools.

Although rectal cancer is by far and large the most common pathology involving the rectum that needs imaging, there are many other important but less common pathological conditions affecting anorectal region. The objective of this pictorial review is to discuss the cross-sectional imaging features of less common anorectal and perirectal diseases.

Although a specific histological diagnosis cannot usually be made due to considerable overlap in the imaging appearances of anorectal diseases, this review illustrates the cross-sectional imaging findings with emphasis on magnetic resonance imaging (MRI) that can help in narrowing down the differentials to a reasonable extent.

• Variety of pathology exists in the anorectum apart from common rectal carcinoma

• Anorectal diseases present as non-specific wall thickening indistinguishable from rectal carcinoma

• Computed tomography (CT) and MRI can help in narrowing down the differentials, although often biopsy is warranted.

Magnetic resonance imaging (MRI) in rectal cancer was first investigated in 1999 and has become almost mandatory in planning rectal cancer treatment. MRI has a high accuracy in predicting circumferential resection margin involvement and is used to plan neoadjuvant therapy. The accuracy of MRI in assessing mesorectal lymph nodes remains moderate, as there are no reliable criteria to assess nodal involvement. MRI seems to be good in assessing peritoneal involvement in upper rectal cancer; this however has been assessed in only a few studies and needs further research. For low rectal cancers, mesorectum is thin at the level of levator ani especially in relation to prostate; so predicting circumferential resection margin involvement is not easy. However high spatial resolution coronal imaging shows levator muscles, sphincter complex and intersphincteric plane accurately. This is used to stage low rectal tumors and plan plane of surgery (standard surgery, intersphincteric resection, Extralevator abdominoperineal resection). While most centres perform MRI post chemoradiotherapy, its role in accurate staging post neoadjuvant therapy remains debatable. THe role of Diffusion weighted MRI post neoadjuvant therapy is being evaluated in research settings.

• Magnetic resonance imaging
• Rectal cancer
• Surgeon

• Chemoradiotherapy
• Diffusion Magnetic Resonance Imaging
• Ferric Compounds/chemistry
• Humans
• Magnetic Resonance Imaging
• Neoadjuvant Therapy
• Neoplasm Staging
• Rectal Neoplasms/pathology
• Rectal Neoplasms/surgery
• Reproducibility of Results
• Treatment Outcome

• Chemotherapy
• Mucin
• Mucinous
• Rectal cancer
• TME

Management of rectal cancer has evolved over the years. In this condition preoperative investigations assist in deciding the optimal treatment. The relation of the tumor edge to the circumferential margin (CRM) is an important factor in deciding the need for neoadjuvant treatment and determines the prognosis. Those with threatened or involved margins are offered long course chemoradiation to enable R₀ surgical resection. Endoanal ultrasound (EUS) is useful for tumor (T) staging; hence EUS is a useful imaging modality for early rectal cancer. Magnetic resonance imaging (MRI) is useful for assessing the mesorectum and the mesorectal fascia which has useful prognostic significance and for early identification of local recurrence. Computerized tomography (CT) of the chest, abdomen and pelvis is used to rule out distant metastasis. Identification of the malignant nodes using EUS, CT and MRI is based on the size, morphology and internal characteristics but has drawbacks. Most of the common imaging techniques are suboptimal for imaging following chemoradiation as they struggle to differentiate fibrotic changes and tumor. In this situation, EUS and MRI may provide complementary information to decide further treatment. Functional imaging using positron emission tomography (PET) is useful, particularly PET/CT fusion scans to identify areas of the functionally hot spots. In the current state, imaging has enabled the multidisciplinary team of surgeons, oncologists, radiologists and pathologists to decide on the patient centered management of rectal cancer. In future, functional imaging may play an active role in identifying patients with lymph node metastasis and those with residual and recurrent disease following neoadjuvant chemoradiotherapy.

• Rectal cancer
• Staging
• Investigations
• Magnetic resonance imaging
• Ultrasound
• Endoanal ultrasound
• Positron emission tomography
• Computerized tomography

• Magnetic resonance
• postoperative
• preoperative
• rectal cancer
• recurrence

• Adenocarcinoma, Mucinous/mortality
• Adenocarcinoma, Mucinous/pathology
• Adenocarcinoma, Mucinous/therapy
• Adult
• Aged
• Aged, 80 and over
• Antimetabolites, Antineoplastic/therapeutic use
• Chemotherapy, Adjuvant
• Digestive System Surgical Procedures
• Disease-Free Survival
• Female
• Fluorouracil/therapeutic use
• Humans
• Male
• Middle Aged
• Neoplasm Staging
• Radiotherapy, Adjuvant
• Rectal Neoplasms/mortality
• Rectal Neoplasms/pathology
• Rectal Neoplasms/therapy
• Survival Rate