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Background: To evaluate the effectiveness of a deep learning denoising approach to accelerate diffusion-weighted imaging (DWI) and thus improve diagnostic accuracy and image quality in restaging rectal MRI following total neoadjuvant therapy (TNT)., Methods: This retrospective single-center study included patients with locally advanced rectal cancer who underwent restaging rectal MRI between December 30, 2021, and June 1, 2022, following TNT. A convolutional neural network trained with DWI data was employed to denoise accelerated DWI acquisitions (i.e., acquisitions performed with a reduced number of repetitions compared to standard acquisitions). Image characteristics and residual disease were independently assessed by two radiologists across original and denoised images. Statistical analyses included the Wilcoxon signed-rank test to compare image quality scores across denoised and original images, weighted kappa statistics for inter-reader agreement assessment, and the calculation of measures of diagnostic accuracy., Results: In 46 patients (median age, 60 years [IQR: 47-72]; 37 men and 9 women), 8- and 16-fold accelerated images maintained or exhibited enhanced lesion visibility and image quality compared with original images that were performed 16 repetitions. Denoised images maintained diagnostic accuracy, with conditional specificities of up to 96 %. Moderate-to-high inter-reader agreement indicated reliable image and diagnostic assessment. The overall test yield for denoised DWI reconstructions ranged from 76-98 %, demonstrating a reduction in equivocal interpretations., Conclusion: Applying a denoising network to accelerate rectal DWI acquisitions can reduce scan times and enhance image quality while maintaining diagnostic accuracy, presenting a potential pathway for more efficient rectal cancer management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rectal cancer management has evolved over the past decade with the emergence of total neoadjuvant therapy (TNT). For select patients who achieve a clinical complete response following TNT, organ preservation by means of the watch-and-wait (WW) strategy is an increasingly adopted alternative that preserves rectal function and quality of life without compromising oncologic outcomes. Recently, published 5-year results from the OPRA trial demonstrated that organ preservation can be achieved in approximately half of patients managed with the WW strategy, with most local regrowth events occurring within two years. Considering the potential for local regrowth, the implementation of the WW strategy mandates rigorous clinical and radiographic surveillance. Magnetic resonance imaging (MRI) serves as the conventional imaging modality for local staging and surveillance of rectal cancer given its excellent soft-tissue resolution. This review will discuss the current evidence for the WW strategy and the role of restaging rectal MRI in determining patient eligibility for this strategy. Restaging rectal MRI acquisition parameters and treatment response assessment, including important factors to assess, pitfalls, and classification systems, will be discussed in the context of the WW strategy., Competing Interests: Declaration of competing interest J.J.S. received travel support for fellow education from Intuitive Surgical (August 2015). He also served as a clinical advisor for Guardant Health (March 2019) and as a clinical advisor for Foundation Medicine (April 2022). He served as a consultant and speaker for Johnson and Johnson (May 2022). And he serves as a clinical advisor and consultant for GlaxoSmithKline (2023-24). The remaining authors disclose no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: To investigate the differences in baseline staging of anal squamous cell carcinoma based on CT, MRI, and PET/CT, and the resultant impact on the radiation plan., Methods: This retrospective study included consecutive patients with anal squamous cell carcinoma who underwent baseline pelvic MRI, CT, and PET/CT (all examinations within 3 weeks of each other) from January 2010 to April 2020. CTs, MRIs, and PET/CTs were re-interpreted by three separate radiologists. Several imaging features were assessed; tumor stage was determined based on the eight edition of the American Joint Committee on Cancer (AJCC) staging manual; and T (tumor), N (node), and M (metastasis) categories were determined based on National Comprehensive Cancer Network (NCCN) guidelines. Radiologist assessments were then randomly presented to a radiation oncologist who formulated the radiation plan in a blinded fashion., Results: Across 28 patients (median age, 62 years [range, 31-78], T-category classification was significantly different on PET/CT compared to MRI and CT (p = 0.037 and 0.031, respectively). PET/CT staged a higher proportion of patients with T1/T2 disease (16/28, 57%) compared to MRI (11/28, 39%) and CT (10/28, 36%). MRI staged a higher proportion of patients with T3/T4 disease (14/28, 50%) compared to CT (12/28, 43%) and PET/CT (11/28, 39%). However, there was no significant difference between the three imaging modalities in terms of either N-category, AJCC staging, or NCCN TNM group classification, or in treatment planning., Conclusion: Our exploratory study showed that MRI demonstrated a higher proportion of T3/T4 tumors, while PET/CT demonstrated more T1/T2 tumors; however, MRI, CT, and PET/CT did not show any significant differences in AJCC and TNM group categories, nor was there any significant difference in treatment doses between them when assessed independently by an experienced radiation oncologist., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Multi-shot echo planar imaging is a promising technique to reduce geometric distortions and increase spatial resolution in diffusion-weighted MRI (DWI), at the expense of increased scan time. Moreover, performing DWI in the body requires multiple repetitions to obtain sufficient signal-to-noise ratio, which further increases the scan time. This work proposes to reduce the number of repetitions and perform denoising of high b-value images using a convolutional network denoising trained on single-shot DWI to accelerate the acquisition of multi-shot DWI. Convolutional network denoising is demonstrated to accelerate the acquisition of 2-shot DWI by a factor of 4 compared to the clinical standard on patients with rectal cancer. Image quality was evaluated using qualitative scores from expert body radiologists between accelerated and non-accelerated acquisition. Additionally, the effect of convolutional network denoising on each image quality score was analyzed using a Wilcoxon signed-rank test. Convolutional network denoising would enable to increase the number of shots without increasing scan time for significant geometric artifact reduction and spatial resolution increase., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Anal cancer treatment response assessment can be challenging with both magnetic resonance imaging (MRI) and clinical evaluation considered essential. MRI, in particular, has shown to be useful for the assessment of treatment response, the detection of recurrent disease in follow up and surveillance, and the evaluation of possible post-treatment complications as well as complications from the tumor itself. In this review, we focus on the role of imaging, mainly MRI, in anal cancer treatment response assessment. We also describe the treatment complications that can occur, and the imaging findings associated with those complications., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Anal cancer is an uncommon malignancy. In addition to squamous cell carcinoma, there are a variety of other less common malignancies and benign pathologies that may afflict the anal canal, with which abdominal radiologists should be familiar. Abdominal radiologists should be familiar with the imaging features that can help distinguish different rare anal tumors beyond squamous cell carcinoma and that can aid in diagnosis therefore help steer management. This review discusses these uncommon pathologies with a focus on their imaging appearance, management, and prognosis., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The role and method of image-based staging of anal cancer has evolved with the rapid development of newer imaging modalities and the need to address the rising incidence of this rare cancer. In 2014, the European Society of Medical Oncology mandated pelvic magnetic resonance imaging (MRI) for anal cancer and subsequently other societies such as the National Comprehensive Cancer Network followed suit with similar recommendations. Nevertheless, great variability exists from center to center and even within individual centers. Notably, this is in stark contrast to the imaging of the anatomically nearby rectal cancer. As participating team members for this malignancy, we embarked on a comprehensive literature review of anal cancer imaging to understand the relative merits of these new technologies which developed after computed tomography (CT), e.g., MRI and positron emission tomography/computed tomography (PET/CT). The results of this literature review helped to inform our next stage: questionnaire development regarding the imaging of anal cancer. Next, we distributed the questionnaire to members of the Society of Abdominal Radiology (SAR) Rectal and Anal Disease-Focused Panel, a group of abdominal radiologists with special interest, experience, and expertise in rectal and anal cancer, to provide expert radiologist opinion on the appropriate anal cancer imaging strategy. In our expert opinion survey, experts advocated the use of MRI in general (65% overall and 91-100% for primary staging clinical scenarios) and acknowledged the superiority of PET/CT for nodal assessment (52-56% agreement for using PET/CT in primary staging clinical scenarios compared to 30% for using MRI). We therefore support the use of MRI and PET and suggest further exploration of PET/MRI as an optimal combined evaluation. Our questionnaire responses emphasized the heterogeneity in imaging practice as performed at numerous academic cancer centers across the United States and underscore the need for further reconciliation and establishment of best imaging practice guidelines for optimized patient care in anal cancer., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This work presents a deep-learning-based denoising technique to accelerate the acquisition of high b -value diffusion-weighted MRI for rectal cancer. A denoising convolutional neural network (DCNN) with a combined L1-L2 loss function was developed to denoise high b -value diffusion-weighted MRI data acquired with fewer repetitions (NEX: number of excitations) using the low b -value image as an anatomical guide. DCNN was trained using 85 datasets acquired on patients with rectal cancer and tested on 20 different datasets with NEX = 1, 2, and 4, corresponding to acceleration factors of 16, 8, and 4, respectively. Image quality was assessed qualitatively by expert body radiologists. Reader 1 scored similar overall image quality between denoised images with NEX = 1 and NEX = 2, which were slightly lower than the reference. Reader 2 scored similar quality between NEX = 1 and the reference, while better quality for NEX = 2. Denoised images with fourfold acceleration (NEX = 4) received even higher scores than the reference, which is due in part to the effect of gas-related motion in the rectum, which affects longer acquisitions. The proposed deep learning denoising technique can enable eightfold acceleration with similar image quality (average image quality = 2.8 ± 0.5) and fourfold acceleration with higher image quality (3.0 ± 0.6) than the clinical standard (2.5 ± 0.8) for improved diagnosis of rectal cancer.

Rectal MR is the key diagnostic exam at initial presentation for rectal cancer patients. It is the primary determinant in establishing clinical stage for the patient and greatly impacts the clinical decision-making process. Consequently, structured reporting for MR is critically important to ensure that all required information is provided to the clinical care team. The SAR initial staging reporting template has been constructed to address these important items, including locoregional extent and factors impacting the surgical approach and management of the patient. Potential outputs to each item are defined, requiring the radiologist to commit to a result. This provides essential information to the surgeon or oncologist to make specific treatment deisions for the patient. The SAR Initial Staging MR reporting template has now been officially adopted by the NAPRC (National Accreditation Program for Rectal Cancer) under the American College of Surgery. With the recent revisions to the reporting template, this user guide has been revamped to improve its practicality and support to the radiologist to complete the structured report. Each line item of the report is supplemented with clinical perspectives, images, and illustrations to help the radiologist understand the potential implications for a given finding. Common errors and pitfalls to avoid are highlighted. Ideally, rectal MR interpretation should not occur in a vacuum but in the context of a multi-disciplinary tumor board to ensure that healthcare providers use common terminology and share a solid understanding of the strengths and weaknesses of MR., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: To review existing structured MRI reports for primary staging of rectal cancer and create a new, freely available structured report based on multidisciplinary expert opinion and literature review., Methods: Twenty abdominal imaging experts from the Society of Abdominal Radiology (SAR)'s Disease Focused Panel (DFP) on Rectal and Anal Cancer completed a questionnaire and participated in a subsequent consensus meeting based on the RAND-UCLA Appropriateness Method. Twenty-two items were classified via a group survey as "appropriate" or "inappropriate" (defined by ≥ 70% consensus), or "needs group discussion" (defined by < 70% consensus). Certain items were also discussed with multidisciplinary team members from colorectal surgery, oncology and pathology., Results: After completion of the questionnaire, 16 (72%) items required further discussion (< 70% consensus). Following group discussion, consensus was achieved for 21 (95%) of the items. Based on the consensus meeting, a revised structured report was developed. The most significant modifications included (1) Exclusion of the T2/early T3 category; (2) Replacement of the term "circumferential resection margin (CRM)" with "mesorectal fascia (MRF)"; (3) A revised definition of "mucinous content"; (4) Creation of two distinct categories for suspicious lymph nodes (LNs) and tumor deposits; and (5) Classification of suspicious extra-mesorectal LNs by anatomic location., Conclusion: The SAR DFP on Rectal and Anal Cancer recommends using this newly updated reporting template for primary MRI staging of rectal cancer., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: Natural language processing (NLP) applied to radiology reports can help identify clinically relevant M1 subcategories of patients with colorectal cancer (CRC). The primary purpose was to compare the overall survival (OS) of CRC according to American Joint Committee on Cancer TNM staging and explore an alternative classification. The secondary objective was to estimate the frequency of metastasis for each organ., Methods: Retrospective study of CRC who underwent computed tomography (CT) chest, abdomen, and pelvis between July 1, 2009, and March 26, 2019, at a tertiary cancer center, previously labeled for the presence or absence of metastasis by an NLP prediction model. Patients were classified in M0, M1a, M1b, and M1c (American Joint Committee on Cancer), or an alternative classification on the basis of the metastasis organ number: M1, single; M2, two; M3, three or more organs. Cox regression models were used to estimate hazard ratios; Kaplan-Meier curves were used to visualize survival curves using the two M1 subclassifications., Results: Nine thousand nine hundred twenty-eight patients with a total of 48,408 CT chest, abdomen, and pelvis reports were included. On the basis of NLP prediction, the median OS of M1a, M1b, and M1c was 4.47, 1.72, and 1.52 years, respectively. The median OS of M1, M2, and M3 was 4.24, 2.05, and 1.04 years, respectively. Metastases occurred most often in liver (35.8%), abdominopelvic lymph nodes (32.9%), lungs (29.3%), peritoneum (22.0%), thoracic nodes (19.9%), bones (9.2%), and pelvic organs (7.5%). Spleen and adrenal metastases occurred in < 5%., Conclusion: NLP applied to a large radiology report database can identify clinically relevant metastatic phenotypes and be used to investigate new M1 substaging for CRC. Patients with three or more metastatic disease organs have the worst prognosis, with an OS of 1 year., Competing Interests: Rona YaegerConsulting or Advisory Role: Array BioPharma, Natera, Mirati TherapeuticsResearch Funding: Array BioPharma (Inst), Boehringer Ingelheim (Inst), Pfizer (Inst), Mirati Therapeutics (Inst) Farhana ZulkernineResearch Funding: Pfizer (Inst), Medlior (Inst) Lior GazitStock and Other Ownership Interests: Within HealthConsulting or Advisory Role: Within Health Huy NguyenEmployment: Caremark LLC David D.B. BatesOther Relationship: GE Healthcare (Inst) Richard DoHonoraria: ALK (I), Genentech (I)Consulting or Advisory Role: DBV Technologies (I), Bayer, GE HealthcarePatents, Royalties, Other Intellectual Property: UptoDate chapters on Food Allergy (I)No other potential conflicts of interest were reported.

Objectives: Describe the cumulative incidence (CUIN) of peritoneal carcinomatosis (PC) and survival in patients presenting with advanced rectal cancer at staging pelvic MRI., Methods: From 2013 to 2018, clinicopathologic records of patients with pretreatment rectal MRI clinical (c)T3c, cT3d, cT4a, and cT4b primary rectal adenocarcinoma were retrospectively reviewed by two radiologists. Standard MRI descriptors and pathologic stages were recorded. Recurrence-free (RFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Development of PC was explored using competing risk analysis. Differences in survival were compared using the log-rank test. Gray's test was used to test for differences in CUIN of PC., Results: Three hundred forty-three patients (147 women; median age, 56 years) had MRI stages cT3cd, n = 170; cT4a, n = 40; and cT4b, n = 133. Median follow-up among survivors was 27 months (0.36-70 months). For M1 patients, OS differed only by cT stage (2-year OS: cT3 88.1%, cT4a 79.1%, cT4b 64.7%, p = 0.045). For M0 patients, OS and RFS differed only by pathological (p)T stage. We observed a statistically significant difference in the cumulative incidence of PC by cT stage (2-year CUIN: cT3 3.2%, cT4a 8.5%, cT4b 1.6%, p = 0.01), but not by pT stage. Seventy-nine patients (23%) presented with metastatic disease (M1), eight with PC (2.3%). Overall, eight patients presented with PC (cT4a: n = 4, other stages: n = 4) and 22 developed PC (cT4a: n = 5, other stages: n = 17)., Conclusions: PC is uncommon in rectal cancer. MRI-based T stage exhibited an overall association with the cumulative incidence of PC, and descriptively, cT4a stage appears to have the highest CUIN., Key Points: • In a retrospective study of 343 patients with rectal cancer undergoing baseline MRI and clinical follow-up, we found that peritoneal carcinomatosis was rare. • We observed a significant overall association between PC at presentation and cT stage that appeared to be driven by the higher proportion of cT4a patients presenting with PC. • Among patients that did not present with PC, we observed a significant overall association between time to PC and cT stage that may be driven by the higher cumulative incidence of PC in cT4a patients., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objective: To interrogate the mesorectal fat using MRI radiomics feature analysis in order to predict clinical outcomes in patients with locally advanced rectal cancer., Methods: This retrospective study included patients who underwent neoadjuvant chemoradiotherapy for locally advanced rectal cancer from 2009 to 2015. Three radiologists independently segmented mesorectal fat on baseline T2-weighted axial MRI. Radiomics features were extracted from segmented volumes and calculated using CERR software, with adaptive synthetic sampling being employed to combat large class imbalances. Outcome variables included pathologic complete response (pCR), local recurrence, distant recurrence, clinical T-category (cT), post-treatment T category (ypT), and post-treatment N category (ypN). A maximum of eight most important features were selected for model development using support vector machines and fivefold cross-validation to predict each outcome parameter via elastic net regularization. Diagnostic metrics of the final models were calculated, including sensitivity, specificity, PPV, NPV, accuracy, and AUC., Results: The study included 236 patients (54 ± 12 years, 135 men). The AUC, sensitivity, specificity, PPV, NPV, and accuracy for each clinical outcome were as follows: for pCR, 0.89, 78.0%, 85.1%, 52.5%, 94.9%, 83.9%; for local recurrence, 0.79, 68.3%, 80.7%, 46.7%, 91.2%, 78.3%; for distant recurrence, 0.87, 80.0%, 88.4%, 58.3%, 95.6%, 87.0%; for cT, 0.80, 85.8%, 56.5%, 89.1%, 49.1%, 80.1%; for ypN, 0.74, 65.0%, 80.1%, 52.7%, 87.0%, 76.3%; and for ypT, 0.86, 81.3%, 84.2%, 96.4%, 46.4%, 81.8%., Conclusion: Radiomics features of mesorectal fat can predict pathological complete response and local and distant recurrence, as well as post-treatment T and N categories., Key Points: • Mesorectal fat contains important prognostic information in patients with locally advanced rectal cancer (LARC). • Radiomics features of mesorectal fat were significantly different between those who achieved complete vs incomplete pathologic response (accuracy 83.9%, 95% CI: 78.6-88.4%). • Radiomics features of mesorectal fat were significantly different between those who did vs did not develop local or distant recurrence (accuracy 78.3%, 95% CI: 72.0-83.7% and 87.0%, 95% CI: 81.6-91.2% respectively)., (© 2021. European Society of Radiology.)

Objectives: To investigate what findings are new on contrast-enhanced abdominopelvic CT in patients infected with SARS-CoV-2., Methods: Contrast-enhanced CT of the abdomen and pelvis of patients with COVID-19 at a tertiary oncologic center acquired over a 2-month period were reviewed independently by two readers and scored for new imaging abnormalities compared with a prior scan. CT scans were included if the study was performed between - 3 and 45 days from the time of COVID-19 diagnosis. Clinical information was gathered from the medical records., Results: A total of 63 patients (34 male, 29 female; mean age 60.6 years, range 24.4-85.0 years) were included in this retrospective cross-sectional study. Aside from new ground glass opacities seen at the lung bases (29/63, 46.0%), the most common findings were new thickening of the stomach, small bowel or colon or fluid-filled colon (14/63, 22.2%), new small volume ascites (7/63, 14.3%), gallbladder distention in those without prior cholecystectomy (3/43, 7.0%), and single cases each of acute pancreatitis (1/63, 1.6%) as well as new portal vein thrombosis (1/63, 1.6%)., Conclusion: Aside from lung base ground glass opacities, the most common new imaging abnormality on abdominopelvic CT in patients with COVID-19 finding in our cohort was abnormalities of the gastrointestinal tract, followed by small volume ascites, gallbladder distention, and isolated cases of pancreatitis and portal vein thrombosis. These findings overlap with those previously reported that did not have a prior scan for comparison, and provide supportive evidence that some of these findings may be related to SARS-CoV-2 infection., (© 2021. American Society of Emergency Radiology.)

Purpose: This study explored the clinicopathologic outcomes of rectal tumor morphological descriptors used in a synoptic rectal MRI reporting template and determined that prognostic differences were observed., Methods: This retrospective study was conducted at a comprehensive cancer center. Fifty patients with rectal tumors for whom the synoptic descriptor "polypoid" was chosen by three experienced radiologists were compared with ninety comparator patients with "partially circumferential" and "circumferential" rectal tumors. Two radiologists re-evaluated all cases. The outcome measures were agreement among two re-interpreting radiologists, clinical T staging with MRI (mrT) and descriptive nodal features, and degrees of wall attachment of tumors (on MRI) compared with pathological (p) T and N stage when available., Results: Re-evaluation by two radiologists showed moderate to excellent agreement in tumor morphology, presence of a pedicle, and degree of wall attachment (k = 0.41-0.76) and excellent agreement on lymph node presence and size (ICC = 0.83-0.91). Statistically significant lower mrT stage was noted for polypoid morphology, wherein 98% were mrT1/2, while only 7% and 2% of partially circumferential and circumferential tumors respectively were mrT1/2. Pathologic T and N stages among the three morphologies also differed significantly, with only 14% of polypoid cases higher than stage pT2 compared to 48% of partially circumferential cases and 60% of circumferential cases., Conclusion: Using a "polypoid" morphology in rectal cancer MRI synoptic reports revealed a seemingly distinct phenotype with lower clinical and pathologic T and N stages when compared with alternative available descriptors., Precis: "Polypoid" morphology in rectal cancer confers a lower clinical and pathologic T and N stage and may be useful in determining whether to proceed with surgery versus neoadjuvant treatment., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: To determine the short-term outcomes of discordant tumor assessments between DWI-MRI and endoscopy in patients with treated rectal cancer when tumor-bed diffusion restriction is present ("+DWI")., Methods: In this HIPPA-compliant, IRB-approved retrospective study, rectal MRI and endoscopic reports were reviewed for patients with locally advanced primary rectal adenocarcinoma (LARC) treated with chemoradiotherapy or total neoadjuvant therapy and imaged between January 2016 and December 2019. Eligible patients had a +DWI and endoscopy within 2 weeks of each other. True positive MRI were those with tumor on endoscopy and/or biopsy (TP a ) or in whom endoscopy was negative for tumor, but subsequent 3-month follow-up endoscopy and DWI were both positive (TP b ). The positive predictive value of DWI-MRI was calculated on a per-scan and per-patient basis. DWI-negative MRI exams were not explored in this study., Results: In total, 397 patients with nonmetastatic primary LARC were analyzed. After exclusions, 90 patients had 98 follow-up rectal MRI studies with +DWI. Seventy-six patients underwent 80 MRI scans and had concordant findings at endoscopy (TPa). Seventeen patients underwent 18 MRI scans and had discordant findings at endoscopy (FP); among these, 4 scans in 4 patients were initially false positive (FP) but follow-up MRI remained +DWI and the endoscopy turned concordantly positive (TP b ). PPV was 0.86 per scan and per patient. In 4/18 (22%) scans and 4/17 (24%) patients with discordances, MRI detected tumor regrowth before endoscopy., Conclusions: Although most +DWI exams discordant with endoscopy are false positive, 22% will reveal that DWI-MRI detects tumor recurrence before endoscopy., Key Points: • Most often, in post-treatment assessment for rectal cancer when DWI-MRI shows restriction in the tumor bed and endoscopy shows no tumor, +DWI MRI will be proven false positive. • Conversely, our study demonstrated that, allowing for sequential follow-up at a 3-month maximum interval, DWI-MRI may detect tumor presence in the treated tumor bed before endoscopy in 22% of discordant findings between DWI-MRI and endoscopy. • Our results showed that a majority of DWI-MRI-positive scans in treated rectal cancer concur with the presence of tumor on endoscopy performed within 2 weeks.

Background: To evaluate quantitative iodine parameters from the arterial phase dual-energy computed tomography (DECT) scans as an imaging biomarker for tumor grade (TG), mitotic index (MI), and Ki-67 proliferation index of hepatic metastases from neuroendocrine tumors (NETs) of the gastrointestinal (GI) tract. Imaging biomarkers have the potential to provide relevant clinical information about pathologic processes beyond lesion morphology. NETs are a group of rare, heterogeneous neoplasms classified by World Health Organization (WHO) TG, which is derived from MI and Ki-67 proliferation index. Imaging biomarkers for these pathologic features and TG may be useful., Methods: Between January 2014 and April 2019, 73 unique patients with hepatic metastases from NET of the GI tract underwent DECT of the abdomen with an arterial phase were analyzed after exclusions. Using GSIViewer software (GE Healthcare, Madison, Wisconsin), elliptical regions of interest (ROIs) were placed over selected hepatic metastases by a fellowship trained abdominal radiologist. Quantitative iodine concentration (IC) data was extracted from the lesion ROIs, and the normalized IC (lesion IC/aorta IC) and relative IC (lesion IC/liver IC) for each liver were calculated. Spearman correlation was calculated for lesion mean IC, normalized IC, and relative IC to both Ki-67 proliferation and mitotic indices. Student's t-test was performed to compare lesion mean IC, normalized IC and relative IC between WHO TGs., Results: There was very weak correlation between both normalized IC and relative IC for both Ki-67 proliferation and mitotic indices. A significant difference was not observed between normalized IC and relative IC to distinguish metastases from G1 and G2/3 tumors., Conclusions: Our study finds limited potential for quantitative parameters from DECT to distinguish neuroendocrine hepatic metastases by WHO TG, as well as limited potential as an imaging biomarker for Ki-67 proliferation and mitotic indices in this setting. Our findings of a lack of correlation between Ki-67 and quantitative iodine parameters stands in contrast to existing literature that reports positive correlations for these parameters in the rectum and stomach., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-917). Dr. DDBB reports research support from GE Healthcare. The other authors have no conflicts of interest to declare., (2021 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Purpose: To determine the most accurate measurement technique to assess rectal tumor height on MRI using two different anatomic landmarks for the anal verge., Introduction: Accurate measurements and standardized reporting of MRI for rectal cancer staging is essential. It is not known whether measurements starting from the internal anal sphincter (IAS) or external anal sphincter (EAS) more closely correlate with tumor height from the anal verge on endoscopy., Methods: This retrospective study included baseline staging MRI examinations for 85 patients after exclusions. Two radiologists blinded to endoscopic results measured the distance of rectal tumors from the internal anal sphincter and external anal sphincter on sagittal T2 images. The reference standard was endoscopic measurement of tumor height; descriptive statistics were performed., Results: For reader 1, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.45 cm (SD ± 1.76 cm, range - 6.0 to 3.9 cm) for the IAS and 0.51 cm (SD ± 1.75 cm range - 4.7 to 4.8 cm) for the EAS. For reader 2, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.57 (STD ± 1.81, range - 5.9 to 4.8 cm) for the IAS and 0.52 cm (STD ± 1.85, range - 4.3 to 5.6 cm) for the EAS. Interobserver ICC was excellent between reader 1 and reader 2 for measurements from both the IAS (0.955 95% CI 0.931-0.97) and EAS (0.952, 95% CI 0.928, 0.969)., Conclusion: Measurement of tumor height on MRI was highly reproducible between readers; beginning measurements from the EAS tends to slightly overestimate tumor height on average and from the IAS tends to slightly underestimate tumor height on average.

We are presenting a compelling case of a 61-year-old female with a history of appendiceal mucinous adenocarcinoma (AMA) with a new complaint of irritative lower urinary tract symptoms. Magnetic resonance imaging (MRI) showed a semi-circumferential, T2 hyperintense, rim enhancing, and lacking restricted diffusion lesion involving the urethra and infiltrating the right perineal and internal obturator muscles. The suspected differential diagnosis was urethral malignancy, based on her cancer history and MRI findings. After interdisciplinary consensus, the patient underwent excision of the lesion, and pathology was consistent with metastasis from the primary tumor. The urethra is a rare site of primary malignancy and metastatic disease. In particular, a non-contiguous metastatic disease involving the urethra is exceedingly rare. To the best of our knowledge, this is the first report of an AMA metastasizing to the urethra., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: To investigate the value of T2-radiomics combined with anatomical MRI staging criteria from pre-treatment rectal MRI in predicting complete response to neoadjuvant chemoradiation therapy (CRT)., Methods: This retrospective study included patients with locally advanced rectal cancer who underwent rectal MRI before neoadjuvant CRT from October 2011 to January 2015 and then surgery. Surgical histopathologic analysis was used as the reference standard for pathologic complete response. Anatomical MRI staging criteria were extracted from our institutional standardized radiology report. In radiomics analysis, one radiologist manually segmented the primary tumor on T2-weighted images for all 102 patients (i.e., training set); two different radiologists independently segmented 66/102 patients (i.e., validation set). 108 radiomics features were extracted. Then, scanner-independent features were identified and least absolute shrinkage operator analysis was used to extract a radiomics score. Finally, a support vector machine model combining the radiomics score and anatomical MRI staging criteria was compared against both anatomical MRI-only and radiomics-only models using the deLong test., Results: The study included 102 patients (42 women; median age = 61 years).The radiomics score produced an area under the curve (AUC) of 0.75. Comparable results were found using the validation set (AUCs = 0.75 and 0.71 for each radiologist, respectively). The anatomical MRI-only model had an accuracy of 67% (sensitivity 42%, specificity 72%); when adding the radiomics score, the accuracy increased to 74% (sensitivity 58%, specificity 77%)., Conclusion: Combining T2-radiomics and anatomical MRI staging criteria from pre-treatment rectal MRI may help to stratify patients based on the prediction of treatment response to neoadjuvant therapy.

Purpose: To compare the sensitivity, specificity and intra-observer and inter-observer agreement of pelvic magnetic resonance imaging (MRI) b800 and b1500 s/mm 2 sequences in the detection of residual adenocarcinoma after neoadjuvant chemoradiation (CRT) for locally advanced rectal cancer (LARC)., Introduction: Detection of residual adenocarcinoma after neoadjuvant CRT for LARC has become increasingly important and relies on both MRI and endoscopic surveillance. Optimal MRI diffusion b values have yet to be established for this clinical purpose., Methods: From our MRI database between 2018 and 2019, we identified a cohort of 28 patients after exclusions who underwent MRI of the rectum before and after neoadjuvant chemoradiation with a protocol that included both b800 and b1500 s/mm 2 diffusion sequences. Four radiologists experienced in rectal MRI interpreted the post-CRT MRI studies with either b800 DWI or b1500 DWI, and a minimum of 2 weeks later re-interpreted the same studies using the other b value sequence. Surgical pathology or endoscopic follow-up for 1 year without tumor re-growth was used as the reference standard. Descriptive statistics compared accuracy for each reader and for all readers combined between b values. Inter-observer agreement was assessed using kappa statistics. A p value of 0.05 or less was considered significant., Results: Within the cohort, 19/28 (67.9%) had residual tumor, while 9/28 (32.1%) had a complete response. Among four readers, one reader had increased sensitivity for detection of residual tumor at b1500 s/mm 2 (0.737 vs. 0.526, p = 0.046). There was no significant difference between detection of residual tumor at b800 and at b1500 for the rest of the readers. With all readers combined, the pooled sensitivity was 0.724 at b1500 versus 0.605 at b800, but this was not significant (p = 0.119). There was no difference in agreement between readers at the two b value settings (67.8% at b800 vs. 72.0% at b1500), or for any combination of individual readers., Conclusion: Aside from one reader demonstrating increased sensitivity, no significant difference in accuracy parameters or inter-observer agreement was found between MR using b800 and b1500 for the detection of residual tumor after neoadjuvant CRT for LARC. However, there was a suggestion of a trend towards increased sensitivity with b1500, and further studies using larger cohorts may be needed to further investigate this topic.

Purpose: To evaluate the role of diffusion kurtosis and diffusivity as potential imaging biomarkers to predict response to neoadjuvant chemoradiation therapy (CRT) from baseline staging magnetic resonance imaging (MRI) in locally advanced rectal cancer (LARC)., Materials and Methods: This retrospective study included 45 consecutive patients (31 male/14 female) who underwent baseline MRI with high b-value sequences (up to 1500 mm/s 2 ) for LARC followed by neoadjuvant chemoradiation and surgical resection. The mean age was 57.4 years (range 34.2-72.9). An abdominal radiologist using open source software manually segmented T2-weighted images. Segmentations were used to derive diffusion kurtosis and diffusivity from diffusion-weighted images as well as volumetric data. These data were analyzed with regard to tumor regression grade (TRG) using the four-tier American Joint Committee on Cancer (AJCC) classification, TRG 0-3. Proportional odds regression was used to analyze the four-level ordinal outcome. A sensitivity analysis was performed using univariable logistic regression for binary TRG groups, TRG 0/1 (> 90% response), or TRG 2/3 (< 90% response). p < 0.05 was considered significant throughout., Results: In the univariable proportional odds regression analysis, higher diffusivity summary (D sum ) values were observed to be significantly associated with higher odds of being in one or more favorable TRG group (TRG 0 or 1). In other words, on average, patients with higher D sum values were more likely to be in a more favorable TRG group. These results are mostly consistent with the sensitivity analysis, in which higher values for most D sum values [all but region of interest (ROI)-max D median (p = 0.08)] were observed to be significantly associated with higher odds of being TRG 0 or 1. Tumor volume of interest (VOI) and ROI volume, ROI kurtosis mean and median, and VOI kurtosis mean and median were not significantly associated with TRG., Conclusion: Diffusivity derived from the baseline staging MRI, but not diffusion kurtosis or volumetric data, is associated with TRG and therefore shows promise as a potential imaging biomarker to predict the response to neoadjuvant chemotherapy in LARC., Clinical Relevance Statement: Diffusivity shows promise as a potential imaging biomarker to predict AJCC TRG following neoadjuvant CRT, which has implications for risk stratification. Patients with TRG 0/1 have 5-year disease-free survival (DFS) of 90-98%, as opposed to those who are TRG 2/3 with 5-year DFS of 68-73%.

Standardized terminology is critical to providing consistent reports to referring clinicians. This lexicon aims to provide a reference for terminology frequently used in rectal cancer and reflects the consensus of the Society of Abdominal Radiology Disease Focused Panel in Rectal cancer. This lexicon divided the terms into the following categories: primary tumor staging, nodal staging, treatment response, anal canal anatomy, general anatomy, and treatments.

Purpose: To predict microsatellite instability (MSI) status of colon cancer on preoperative CT imaging using radiomic analysis., Methods: This retrospective study involved radiomic analysis of preoperative CT imaging of patients who underwent resection of stage II-III colon cancer from 2004 to 2012. A radiologist blinded to MSI status manually segmented the tumor region on CT images. 254 Intensity-based radiomic features were extracted from the tumor region. Three prediction models were developed with (1) only clinical features, (2) only radiomic features, and (3) "combined" clinical and radiomic features. Patients were randomly separated into training (n = 139) and test (n = 59) sets. The model was constructed from training data only; the test set was reserved for validation only. Model performance was evaluated using AUC, sensitivity, specificity, PPV, and NPV., Results: Of the total 198 patients, 134 (68%) patients had microsatellite stable tumors and 64 (32%) patients had MSI tumors. The combined model performed slightly better than the other models, predicting MSI with an AUC of 0.80 for the training set and 0.79 for the test set (specificity = 96.8% and 92.5%, respectively), whereas the model with only clinical features achieved an AUC of 0.74 and the model with only radiomic features achieved an AUC of 0.76. The model with clinical features alone had the lowest specificity (70%) compared with the model with radiomic features alone (95%) and the combined model (92.5%)., Conclusions: Preoperative prediction of MSI status via radiomic analysis of preoperative CT adds specificity to clinical assessment and could contribute to personalized treatment selection.

Anal canal cancer is a rare disease and squamous cell carcinoma is the most common histologic subtype. Traditionally, anal cancer is imaged with CT and PET/CT for purposes of TNM staging. With the increased popularity of MRI for rectal cancer evaluation, MRI has become increasingly utilized for local staging of anal cancer. In this review, we focus on the necessary information radiologists need to know to understand this rare and unique disease and to be familiar with staging of anal cancer on MRI.

Purpose: To evaluate for stability of perifissural nodules (PFNs) in a dedicated oncologic population., Methods: A retrospective review of 500 computed tomography (CT) chests from oncologic patients at our tertiary care cancer center with at least a three year follow up yielded 76 patients with PFNs. Patients with metastases on baseline CT chest were excluded (n = 14) as the presence of a PFN would not be clinically relevant, thus our final patient cohort was 62 patients with a total of 112 PFNs. PFN features, clinical features, and ancillary information was recorded from the CT and the electronic medical record for all patients. The two patient cohorts-stable or decreased PFN vs. increased PFN-were then compared., Results: 112 PFNs were examined in 62 patients with a median follow up interval of 5.7 years. Of 62 patients, 59 (95.2%, 95% CI: 86.5, 99.0) had decreased/stable PFNs on follow up scan (median follow up 5.6 years) and 3 (4.8%, 95% CI: 1.0, 13.5%) had enlarged PFNs (median follow up 6.3 years). None of the PFN features, clinical features, nor ancillary information from the CT proved to be statistically significant., Conclusions: Despite the lack of statistically significant distinguishing features to predict growth, our results are reassuring, since the majority of PFNs in our oncology patients were decreased or unchanged in size which is comparable to previously published data on PFNs in non-oncologic patients. Thus, we can similarly presume these nodules are most likely benign and can provide reassurance to our oncologic colleagues and our patients. Larger studies are warranted to further evaluate PFNs in the oncologic population which also examines the nodules by cancer type., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To investigate associations between genetic mutations and qualitative as well as quantitative features on MRI in rectal adenocarcinoma at primary staging., Methods: In this retrospective study, patients with rectal adenocarcinoma, genome sequencing, and pretreatment rectal MRI were included. Statistical analysis was performed to evaluate associations between qualitative features obtained from subjective evaluation of rectal MRI and gene mutations as well as between quantitative textural features and gene mutations. For the qualitative evaluation, Fisher's Exact test was used to analyze categorical associations and Wilcoxon Rank Sum test was used for continuous clinical variables. For the quantitative evaluation, we performed manual segmentation of T2-weighted images for radiomics-based quantitative image analysis. Thirty-four texture features consisting of first order intensity histogram-based features (n = 4), second order Haralick textures (n = 5), and Gabor-edge based Haralick textures were computed at two different orientations. Consensus clustering was performed with 34 computed texture features using the K-means algorithm with Euclidean distance between the texture features. The clusters resulting from the algorithm were then used to enumerate the prevalence of gene mutations in those clusters., Results: In 65 patients, 45 genes were mutated in more than 3/65 patients (5%) and were included in the statistical analysis. Regarding qualitative imaging features, on univariate analysis, tumor location was significantly associated with APC (p = 0.032) and RASA1 mutation (p = 0.032); CRM status was significantly associated with ATM mutation (p = 0.021); and lymph node metastasis was significantly associated with BRCA2 (p = 0.046) mutation. However, these associations were not significant after adjusting for multiple comparisons. Regarding quantitative imaging features, Cluster C1 had tumors with higher mean Gabor edge intensity compared with cluster C2 (θ = 0°, p = 0.018; θ = 45°, p = 0.047; θ = 90°, p = 0.037; cluster C3 (θ = 0°, p = 0.18; θ = 45°, p = 0.1; θ = 90°, p = 0.052), and cluster C4 (θ = 0°, p = 0.016; θ = 45°, p = 0.033; θ = 90°, p = 0.014) suggesting that the cluster C1 had tumors with more distinct edges or heterogeneous appearance compared with other clusters., Conclusions: Although this preliminary study showed promising associations between quantitative features and genetic mutations, it did not show any correlation between qualitative features and genetic mutations. Further studies with larger sample size are warranted to validate our preliminary data., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Rationale and Objectives: The purpose of this study is to compare image quality, presence and grade of artifacts, signal-to-noise ratio, and apparent diffusion coefficient (ADC) values in pancreatic tissue between high-resolution navigator-triggered (NT) restricted field of view (rFOV) FOCUS single-shot (SS) echo-planar imaging (EPI) diffusion-weighted imaging (DWI) and NT large FOV SS-EPI DWI., Materials and Methods: Magnetic resonance imaging examinations were performed with GE 3-T systems using a 32-channel body array coil. Seventeen consecutive patients were imaged. A 5-point scale semiquantitative grading system was used to evaluate image quality and general artifacts. Signal-to-noise ratio and ADC were measured in the head, body, and tail of the pancreas. Statistical analysis was performed using Student t test and Wilcoxon signed rank test, with differences considered significant for P value less than 0.05., Results: More artifacts were present on large FOV compared with rFOV FOCUS SS-EPI DW images (P < 0.01). Restricted field of view image quality was subjectively better (P < 0.01). No difference in the signal-to-noise ratio was demonstrated between the 2 image datasets. Apparent diffusion coefficient values were significantly lower (P < 0.01) when calculated from rFOV images than large FOV images., Conclusions: Our results demonstrate better image quality and reduced artifacts in rFOV images compared with large FOV DWI. Measurements from ADC maps derived from rFOV DWI show significantly lower ADC values when compared with ADC maps derived from large FOV DWI.

Benign multicystic peritoneal mesothelioma (BMPM) is a rare entity with fewer than 150 reported cases in the literature. Here we discuss a case of BMPM in a 22-year old female as presented to our urban community hospital, review epidemiology and clinical presentations of this entity, and perform a comprehensive literature review of various CT, US, and MR imaging features of BMPM., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Clinical trials evaluating the benefit of pelvic radiotherapy (PRT) in the radiotherapeutic management of patients with higher-risk prostate cancer have limited the superior field border to the S1/S2 or L5/S1 interspace. However, imaging and surgical series have demonstrated a high frequency of prostatic lymph node (LN) drainage beyond these landmarks., Objective: To determine the patterns of radiographically defined abdominopelvic LN failures and their potential implications for PRT field design., Design, Setting, and Participants: During 1992-2008, 2694 patients with localized prostate cancer were treated with prostate/seminal vesicle-only radiotherapy without PRT. Some 156 patients had their first failure within the abdominopelvic LNs, of whom 60 had isolated failures within the pelvic LNs., Outcome Measurements and Statistical Analysis: A radiologist reviewed all imaging and mapped each LN failure to a template consisting of 34 abdominopelvic LN stations., Results and Limitations: The median follow-up was 8.9 yr. Of patients who experienced first recurrence in the pelvic LNs (n=60), the common iliac station was involved in 55% (n=33) of patients, including 10% (n=6) who had isolated common iliac failures. Use of a PRT field superior border of L5/S1 would fully cover only 42% of the first recurrences among these patients. Extending the field to cover the common iliac stations would increase coverage to 93% of recurrences. The presence of T3/T4 disease and omission of androgen-deprivation therapy both independently conferred an approximate fivefold increase in the likelihood of having a common iliac LN failure. Use of imaging as a surrogate for LN involvement is the primary study limitation., Conclusions: Pelvic LN failures frequently occur superior to the commonly used L5/S1 landmark for PRT coverage, and use of ADT may be protective of more superior LN failures. The current RTOG 0924 trial is evaluating the benefit of PRT with extended superior coverage to L4/5 when possible, which, according to our data, should significantly improve the coverage of potential sites of failure., Patient Summary: We looked at lymph node recurrence patterns after external beam radiotherapy of the prostate in men who did not have their lymph nodes treated. We found that there was a high incidence of pelvic lymph node recurrences above the internal and external iliac lymph node regions. Therefore, the current field recommendation for pelvic lymph nodes that stops at the superior border of the internal and external iliac vessels provides inadequate coverage of common sites of cancer recurrence, namely the common iliac lymph nodes., (Copyright © 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.)