The Role of Imaging for Gastrointestinal Bleeding: Consensus Recommendations From the American College of Gastroenterology and Society of Abdominal Radiology.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high healthcare utilization and costs. Radiologic techniques including computed tomography angiography, catheter angiography, computed tomography enterography, magnetic resonance enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided.

A global consensus on the definitions, diagnosis and management of fibrostenosing small bowel Crohn's disease in clinical practice.

Fibrostenosis of the small bowel is common in patients with Crohn's disease. No consensus recommendations on definition, diagnosis and management in clinical practice are currently available. In this Consensus Statement, we present a clinical practice RAND/UCLA appropriateness study on the definition, diagnosis and clinical management of fibrostenosing Crohn's disease. It was conducted by a panel of 28 global experts and one patient representative. Following a systematic literature review, 526 candidate items grouped into 136 questions were generated and subsequently evaluated for appropriateness. Strictures are best defined as wall thickening, luminal narrowing and prestenotic dilation. Cross-sectional imaging is required for accurate diagnosis of fibrostenosing Crohn's disease, and it is recommended before making treatment decisions. It should also assess the degree of inflammation in the bowel wall. Multiple options for medical anti-inflammatory, endoscopic and surgical therapies were suggested, including follow-up strategies following therapy. This Consensus Statement supports clinical practice through providing guidance on definitions, diagnosis and therapeutic management of patients with fibrostenosing small bowel Crohn's disease.

MRI and Blood-based Biomarkers Are Associated With Surgery in Children and Adults With Ileal Crohn's Disease.

BACKGROUND: Despite advances in medical therapy, many children and adults with ileal Crohn's disease (CD) progress to fibrostenosis requiring surgery. We aimed to identify MRI and circulating biomarkers associated with the need for surgical management. METHODS: This prospective, multicenter study included pediatric and adult CD cases undergoing ileal resection and CD controls receiving medical therapy. Noncontrast research MRI examinations measured bowel wall 3-dimensional magnetization transfer ratio normalized to skeletal muscle (normalized 3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, intravoxel incoherent motion (IVIM) diffusion-weighted imaging metrics, and the simplified magnetic resonance index of activity (sMaRIA). Circulating biomarkers were measured on the same day as the research MRI and included CD64, extracellular matrix protein 1 (ECM1), and granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies (Ab). Associations between MRI and circulating biomarkers and need for ileal resection were tested using univariate and multivariable LASSO regression. RESULTS: Our study sample included 50 patients with CD undergoing ileal resection and 83 patients with CD receiving medical therapy; mean participant age was 23.9 ±â€…13.1 years. Disease duration and treatment exposures did not vary between the groups. Univariate biomarker associations with ileal resection included log GM-CSF Ab (odds ratio [OR], 2.87; P = .0009), normalized 3D MTR (OR, 1.05; P = .002), log MOLLI T1 (OR, 0.01; P = .02), log IVIM perfusion fraction (f; OR, 0.38; P = .04), and IVIM apparent diffusion coefficient (ADC; OR, 0.3; P = .001). The multivariable model for surgery based upon corrected Akaike information criterion included age (OR, 1.03; P = .29), BMI (OR, 0.91; P = .09), log GM-CSF Ab (OR, 3.37; P = .01), normalized 3D MTR (OR, 1.07; P = .007), sMaRIA (OR, 1.14; P = .61), luminal narrowing (OR, 10.19; P = .003), log C-reactive protein (normalized; OR, 2.75; P = .10), and hematocrit (OR, 0.90; P = .13). CONCLUSION: After accounting for clinical and MRI measures of severity, normalized 3D MTR and GM-CSF Ab are associated with the need for surgery in ileal CD.

Despite advances in medical therapy, many patients with ileal Crohn's disease progress to fibrostenosis requiring surgery. Our study has shown that GM-CSF autoantibodies and MRI biomarker sequences are associated with the need for ileal resection and may help guide management decisions.

Radiomics to Detect Inflammation and Fibrosis on Magnetic Resonance Enterography in Stricturing Crohn's Disease.

BACKGROUND & AIMS: Non-invasive cross-sectional imaging via magnetic resonance enterography (MRE) offers excellent accuracy for the diagnosis of stricturing complications in Crohn's disease (CD) but is limited in determining the degrees of fibrosis and inflammation within a stricture. We developed and validated a radiomics-based machine-learning model for separately characterizing the degree of histopathologic inflammation and fibrosis in CD strictures and compared it to centrally read visual radiologist scoring of MRE. METHODS: This single center, cross-sectional study, included 51 CD patients (n=34 for discovery; n=17 for validation) with terminal ileal strictures confirmed on diagnostic MRE within 15 weeks of resection. Histopathological specimens were scored for inflammation and fibrosis and spatially linked with corresponding pre-surgical MRE sequences. Annotated stricture regions on MRE were scored visually by radiologists as well as underwent 3D radiomics-based machine learning analysis; both evaluated against histopathology. RESULTS: Two distinct sets of radiomic features capturing textural heterogeneity within strictures were linked with each of severe inflammation or severe fibrosis across both discovery (area under the curve (AUC)=0.69, 0.83) and validation (AUCs=0.67,0.78) cohorts. Radiologist visual scoring had an AUC=0.67 for identifying severe inflammation and AUC=0.35 for severe fibrosis. Use of combined radiomics and radiologist scoring robustly augmented identification of severe inflammation (AUC=0.79) and modestly improved assessment of severe fibrosis (AUC=0.79 for severe fibrosis) over individual approaches. CONCLUSIONS: Radiomic features of CD strictures on MRE can accurately identify severe histopathologic inflammation and severe histopathologic fibrosis, as well as augment performance of radiologist visual scoring in stricture characterization.

Systematic review: Defining, diagnosing and monitoring small bowel strictures in Crohn's disease on intestinal ultrasound.

BACKGROUND: Stricturing Crohn's disease (CD) occurs most commonly in the terminal ileum and poses a clinical problem. Cross-sectional imaging modalities such as intestinal ultrasound (IUS), computed tomography enterography (CTE), and magnetic resonance enterography (MRE) allow for assessment of the entire bowel wall and associated peri-enteric findings. Radiologic definitions of strictures have been developed for CTE and MRE; their reliability and responsiveness are being evaluated in index development programs. A comprehensive assessment strategy for strictures using IUS is needed. AIMS: To provide a detailed summary of definitions, diagnosis and monitoring of strictures on IUS as well as technical aspects of image acquisition. METHODS: We searched four databases up to 6 January 2024. Two-stage screening was done in duplicate. We assessed risk of bias using QUADAS-2. RESULTS: There were 56 studies eligible for inclusion. Definitions for strictures on IUS are heterogeneous, but the overall accuracy for diagnosis of strictures is high. The capability of IUS for characterising inflammation versus fibrosis in strictures is not accurate enough to be used in clinical practice or trials. We summarise definitions for improvement of strictures on IUS, and discuss parameters for image acquisition and standardisation. CONCLUSIONS: This systematic review is the first step for a structured program to develop a stricture IUS index for CD.

The Role of Imaging for GI Bleeding: ACG and SAR Consensus Recommendations.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high health care utilization and costs. Radiologic techniques including CT angiography, catheter angiography, CT enterography, MR enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist, which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided. © Radiological Society of North America and the American College of Gastroenterology, 2024. Supplemental material is available for this article. This article is being published concurrently in American Journal of Gastroenterology and Radiology. The articles are identical except for minor stylistic and spelling differences in keeping with each journal's style. Citations from either journal can be used when citing this article. See also the editorial by Lockhart in this issue.

Radiographic Evaluation of Ileal Pouch Disorders: A Systematic Review.

BACKGROUND: Radiographic imaging of the abdomen and pelvis plays an important role in the diagnosis and management of ileal pouch disorders with modalities including CT, MRI, contrasted pouchography, and defecography. OBJECTIVES: To perform a systematic review of the literature and describe applications of cross-sectional imaging, pouchography, defecography, and ultrasonography. DATA SOURCES: PubMed, Google Scholar, and Cochrane database. STUDY SELECTION: Relevant articles on endoscopy in ileal pouches published between January 2003 and June 2023 in English were included on the basis of Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. INTERVENTION: Main abdominal and pelvic imaging modalities and their applications in the diagnosis of ileal pouch disorders were included. MAIN OUTCOME MEASURES: Accuracy in characterization of ileal pouch disorders. RESULTS: CT is the test of choice for the evaluation of acute anastomotic leaks, perforation, and abscess(es). MRI of the pelvis is suitable for the assessment of chronic anastomotic leaks and their associated fistulas and sinus tracts, as well as for the penetrating phenotype of Crohn's disease of the pouch. CT enterography and magnetic resonance enterography are useful in assessing intraluminal, intramural, and extraluminal disease processes of the pouch and prepouch ileum. Water-soluble contrast pouchography is particularly useful for evaluating acute or chronic anastomotic leaks and outlines the shape and configuration of the pouch. Defecography is the key modality to evaluate structural and functional pouch inlet and outlet obstructions. Ultrasonography can be performed to assess the pouch in experienced IBD centers. LIMITATIONS: This is a qualitative, not quantitative, review of mainly case series and case reports. CONCLUSIONS: Abdominopelvic imaging, along with clinical and endoscopic evaluation, is imperative for accurately assessing structural, inflammatory, functional, and neoplastic disorders. See video from symposium .

Diagnostic Performance of a Fecal Calprotectin Assay as a Biomarker for Mayo Endoscopic Subscore in Ulcerative Colitis: Result From a Tertiary Referral Center.

BACKGROUND: Fecal calprotectin (FC) is a promising biomarker for assessing ulcerative colitis (UC) endoscopic activity. However, the optimal FC cutoff to identify each Mayo endoscopic subscore (MES) remains inconclusive. METHODS: The electronic medical records of 177 adult UC patients evaluated at Mayo Clinic Rochester from January 2017 to March 2023 were retrospectively reviewed, obtaining clinical data and US-based Werfen Diagnostics FC levels collected within 30 days before colonoscopy or flexible sigmoidoscopy. Three independent inflammatory bowel disease specialist endoscopists blindly reviewed the most severe endoscopic images for grading MES. RESULTS: The median interval between FC collection and endoscopy was 2 days. Fecal calprotectin showed strong positive correlations with MES (Spearman's r = 0.709; P < .01) and other clinical parameters. Fecal calprotectin cutoff of 60 mcg/g effectively distinguished MES 0 from MES 1-3 (sensitivity, 0.78; specificity, 0.97; area under the receiver operating characteristic curve [AUC], 0.901) and predicted clinical remission (Total Mayo Score ≤2 and no subscore >1; sensitivity, 0.83; specificity, 0.98; AUC, 0.921). Fecal calprotectin cutoff of 110 mcg/g effectively differentiated MES 0-1 from MES 2-3 (sensitivity, 0.86; specificity, 0.87; AUC, 0.915), while a cutoff of 310 mcg/g distinguished MES 0-2 from MES 3 (sensitivity, 0.80; specificity, 0.76; AUC, 0.820). CONCLUSIONS: This study supports the reliability and applicability of FC as a valuable marker of endoscopic inflammation, particularly in distinguishing MES 0 from MES 1-3 using the FC cutoff of 60 mcg/g. Sensitivity analysis demonstrated robust results.

This study from a tertiary referral center evaluated 177 patients with ulcerative colitis and found that a fecal calprotectin cutoff of 60 mcg/g effectively distinguished between a Mayo endoscopic subscore (MES) 0 and MES 1-3, as well as clinical remission, with high specificity, supporting its reliability as a valuable biomarker.

Sociodemographic Factors and Screening CT Colonography Use Among Medicare Beneficiaries.

BACKGROUND. Approximately one-third of the eligible U.S. population have not undergone guideline-compliant colorectal cancer (CRC) screening. Guidelines recognize various screening strategies to increase adherence. CMS provides coverage for all recommended screening tests except CT colonography (CTC). OBJECTIVE. The purpose of this study was to compare CTC and other CRC screening tests in terms of associations of utilization with income, race and ethnicity, and urbanicity in Medicare fee-for-service beneficiaries. METHODS. This retrospective study used CMS Research Identifiable Files from January 1, 2011, through December 31, 2020. These files contain claims information for 5% of Medicare fee-for-service beneficiaries. Data were extracted for individuals 45-85 years old, and individuals with high CRC risk were excluded. Multivariable logistic regression models were constructed to determine the likelihood of undergoing CRC screening tests (as well as of undergoing diagnostic CTC, a CMS-covered test with similar physical access as screening CTC) as a function of income, race and ethnicity, and urbanicity while controlling for sex, age, Charlson comorbidity index, U.S. census region, screening year, and related conditions and procedures. RESULTS. For 12,273,363 beneficiary years (mean age, 70.5 ± 8.2 [SD] years; 2,436,849 unique beneficiaries: 6,774,837 female beneficiaries, 5,498,526 male beneficiaries), there were 785,103 CRC screenings events, including 645 for screening CTC. Compared with individuals living in communities with per capita income of less than US$25,000, individuals in communities with income of US$100,000 or more had OR for undergoing screening CTC of 5.73, optical colonoscopy (OC) of 1.36, sigmoidoscopy of 1.03, guaiac fecal occult blood test or fecal immunochemical test of 1.50, stool DNA of 1.43, and diagnostic CTC of 2.00. The OR for undergoing screening CTC was 1.00 for Hispanic individuals and 1.08 for non-Hispanic Black individuals compared with non-Hispanic White individuals. Compared with the OR for undergoing screening CTC for residents of metropolitan areas, the OR was 0.51 for residents of micropolitan areas and 0.65 for residents of small or rural areas. CONCLUSION. The association with income was substantially larger for screening CTC than for other CRC screening tests or for diagnostic CTC. CLINICAL IMPACT. Medicare's noncoverage for screening CTC may contribute to lower adherence with CRC screening guidelines for lower-income beneficiaries. Medicare coverage of CTC could reduce income-based disparities for individuals avoiding OC owing to invasiveness, need for anesthesia, or complication risk.

Systematic Review and Meta-analysis: The Association Between Serum Ustekinumab Trough Concentrations and Treatment Response in Inflammatory Bowel Disease.

BACKGROUND: Optimizing therapy and monitoring response are integral aspects of inflammatory bowel disease treatment. We conducted a systematic review and meta-analysis to determine whether serum ustekinumab trough concentrations during maintenance therapy were associated with ustekinumab treatment response in patients with inflammatory bowel disease. METHODS: A systematic review was performed to March 21, 2022, to identify studies using MEDLINE, EMBASE, and the Cochrane library. We included studies that reported the association between serum ustekinumab trough concentrations with clinical or endoscopic remission. Outcome measures were combined across studies using the random-effects model with an odds ratio (OR) for binary outcomes of endoscopic and clinical remission. RESULTS: We identified 14 observational studies that were included in the analysis for clinical remission (919 patients, 63% with Crohn's disease) or endoscopic remission (290 patients, all with Crohn's disease). Median ustekinumab trough concentrations were higher amongst individuals achieving clinical remission compared with those not achieving remission (mean difference, 1.6 ug/mL; 95% confidence interval [CI], 0.21-3.01 ug/mL). Furthermore, individuals with median serum trough concentration in the fourth quartile were significantly more likely to achieve clinical (OR, 3.61; 95% CI, 2.11-6.20) but not endoscopic remission (OR, 4.67; 95% CI, 0.86-25.19) compared with those with first quartile median trough concentrations. CONCLUSION: Based on the results of this meta-analysis primarily relating to patients with Crohn's disease on maintenance ustekinumab treatment, it appears that there is an association between higher ustekinumab trough concentration and clinical outcomes. Prospective studies are required to determine whether proactive dose adjustments of ustekinumab therapy provides additional clinical benefit.

This meta-analysis of 14 observational studies found an association between better clinical outcomes and higher trough ustekinumab levels for maintenance treatment in inflammatory bowel disease.

Development of an MRI-Based Prediction Model for Anti-TNF Treatment Failure in Perianal Crohn's Disease: A Multicenter Study.

BACKGROUND & AIMS: Clinical and radiologic variables associated with perianal fistula (PAF) outcomes are poorly understood. We developed prediction models for anti-tumor necrosis factor (TNF) treatment failure in patients with Crohn's disease-related PAF. METHODS: In a multicenter retrospective study between 2005 and 2022 we included biologic-naive adults (>17 years) who initiated their first anti-TNF therapy for PAF after pelvic magnetic resonance imaging (MRI). Pretreatment MRI studies were prospectively reread centrally by blinded radiologists. We developed and internally validated a prediction model based on clinical and radiologic parameters to predict the likelihood of anti-TNF treatment failure, clinically, at 6 months. We compared our model and a simplified version of MRI parameters alone with existing imaging-based PAF activity indices (MAGNIFI-CD and modified Van Assche MRI scores) by De Long statistical test. RESULTS: We included 221 patients: 32 ± 14 years, 60% males, 76% complex fistulas; 68% treated with infliximab and 32% treated with adalimumab. Treatment failure occurred in 102 (46%) patients. Our prediction model included age at PAF diagnosis, time to initiate anti-TNF treatment, and smoking and 8 MRI characteristics (supra/extrasphincteric anatomy, fistula length >4.3 cm, primary tracts >1, secondary tracts >1, external openings >1, tract hyperintensity on T1-weighted imaging, horseshoe anatomy, and collections >1.3 cm). Our full and simplified MRI models had fair discriminatory capacity for anti-TNF treatment failure (concordance statistic, 0.67 and 0.65, respectively) and outperformed MAGNIFI-CD (P = .002 and < .0005) and modified Van Assche MRI scores (P < .0001 and < .0001), respectively. CONCLUSIONS: Our risk prediction models consisting of clinical and/or radiologic variables accurately predict treatment failure in patients with PAF.

A novel blood-sensing capsule for rapid detection of upper GI bleeding: a prospective clinical trial.

BACKGROUND AND AIMS: Upper GI bleeding (UGIB) is a common medical emergency associated with high resource utilization, morbidity, and mortality. Timely EGD can be challenging from personnel, resource, and access perspectives. PillSense (EnteraSense Ltd, Galway, Ireland) is a novel swallowed bleeding sensor for the detection of UGIB, anticipated to aid in patient triage and guide clinical decision-making for individuals with suspected UGIB. METHODS: This prospective, open-label, single-arm comparative clinical trial of a novel bleeding sensor for patients with suspected UGIB was performed at a tertiary care center. The PillSense system consists of an optical sensor and an external receiver that processes and displays data from the capsule as "Blood Detected" or "No Blood Detected." Patients underwent EGD within 4 hours of capsule administration; participants were followed up for 21 days to confirm capsule passage. RESULTS: A total of 126 patients were accrued to the study (59.5% male; mean age, 62.4 ± 14.3 years). Sensitivity and specificity for detecting the presence of blood were 92.9% (P = .02) and 90.6% (P < .001), respectively. The capsule's positive and negative predictive values were 74.3% and 97.8%, and positive and negative likelihood ratios were 9.9 and .08. No adverse events or deaths occurred related to the PillSense system, and all capsules were excreted from patients on follow-up. CONCLUSIONS: The PillSense system is safe and effective for detecting the presence of blood in patients evaluated for UGIB before upper GI endoscopy. It is a rapidly deployed tool, with easy-to-interpret results that will affect the diagnosis and triage of patients with suspected UGIB. (Clinical trial registration number: NCT05385224.).

Defining the Roles of Inflammatory Bowel Disease Clinical Pharmacists in the United States: A Systematic Review and National RAND/UCLA Consensus.

BACKGROUND: Given the complexity of inflammatory bowel disease (IBD) care, utilization of multidisciplinary teams is recommended to optimize outcomes. There is a growing recognition that clinical pharmacists should be an integral part of this care model. We sought to define the roles of IBD clinical pharmacists in the United States. METHODS: A national multidisciplinary expert panel of 12 gastroenterologists and clinical pharmacists practicing in IBD clinics was assembled. We used the RAND/University of California, Los Angeles appropriateness method, with a total of 281 statements generated based on a systematic literature review and expert opinion. Each statement was anonymously rated as appropriate, uncertain, or inappropriate in 2 rounds of voting. RESULTS: The number of publications evaluating the clinical pharmacists' roles in IBD is limited, primarily focusing on thiopurine initiation and monitoring, medication adherence, and switching to biosimilars. Medication education; medication initiation and monitoring; therapeutic drug monitoring; biosimilar management; health maintenance review; and transitions of care were deemed by the panel to be appropriate roles for IBD clinical pharmacists. In considering real-world settings, IBD clinical pharmacists should practice clinically under a predefined scope and primarily focus on complex treatments (eg, immunomodulators, biologics, and small molecules). Clinical pharmacists should also be included in practice settings with IBD specialized physicians. Additionally, clinical pharmacists caring for patients with IBD should be residency trained and board certified. CONCLUSIONS: This consensus defines IBD clinical pharmacists' roles and provides a framework for embedded clinical pharmacists in IBD care.

Dual-Energy CT Evaluation of Gastrointestinal Bleeding.

Gastrointestinal (GI) bleeding is a potentially life-threatening condition accounting for more than 300 000 annual hospitalizations. Multidetector abdominopelvic CT angiography is commonly used in the evaluation of patients with GI bleeding. Given that many patients with severe overt GI bleeding are unlikely to tolerate bowel preparation, and inpatient colonoscopy is frequently limited by suboptimal preparation obscuring mucosal visibility, CT angiography is recommended as a first-line diagnostic test in patients with severe hematochezia to localize a source of bleeding. Assessment of these patients with conventional single-energy CT systems typically requires the performance of a noncontrast series followed by imaging during multiple postcontrast phases. Dual-energy CT (DECT) offers several potential advantages for performing these examinations. DECT may eliminate the need for a noncontrast acquisition by allowing the creation of virtual noncontrast (VNC) images from contrast-enhanced data, affording significant radiation dose reduction while maintaining diagnostic accuracy. VNC images can help radiologists to differentiate active bleeding, hyperattenuating enteric contents, hematomas, and enhancing masses. Additional postprocessing techniques such as low-kiloelectron voltage virtual monoenergetic images, iodine maps, and iodine overlay images can increase the conspicuity of contrast material extravasation and improve the visibility of subtle causes of GI bleeding, thereby increasing diagnostic confidence and assisting with problem solving. GI bleeding can also be diagnosed with routine single-phase DECT scans by constructing VNC images and iodine maps. Radiologists should also be aware of the potential pitfalls and limitations of DECT. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Rectal cancer pelvic recurrence: imaging patterns and key concepts to guide treatment planning.

For rectal cancer, MRI plays an important role in assessing extramural tumor spread and informs surgical planning. The contemporary standardized management of rectal cancer with total mesorectal excision guided by imaging-based risk stratification has dramatically improved patient outcomes. Colonoscopy and CT are utilized in surveillance after surgery to detect intraluminal and extramural recurrence, respectively; however, local recurrence of rectal cancer remains a challenge because postoperative changes such as fat necrosis and fibrosis can resemble tumor recurrence; additionally, mucinous adenocarcinoma recurrence may mimic fluid collection or abscess on CT. MRI and 18F-FDG PET are problem-resolving modalities for equivocal imaging findings on CT. Treatment options for recurrent rectal cancer include pelvic exenteration to achieve radical (R0 resection) resection and intraoperative radiation therapy. After pathologic diagnosis of recurrence, imaging plays an essential role for evaluating the feasibility and approach of salvage surgery. Patterns of recurrence can be divided into axial/central, anterior, lateral, and posterior. Some lateral and posterior recurrence patterns especially in patients with neurogenic pain are associated with perineural invasion. Cross-sectional imaging, especially MRI and 18F-FDG PET, permit direct visualization of perineural spread, and contribute to determining the extent of resection. Multidisciplinary discussion is essential for treatment planning of locally recurrent rectal cancer. This review article illustrates surveillance strategy after initial surgery, imaging patterns of rectal cancer recurrence based on anatomic classification, highlights imaging findings of perineural spread on each modality, and discusses how resectability and contemporary surgical approaches are determined based on imaging findings.

Interobserver agreement of the modified Paris classification and histology prediction of colorectal lesions in patients with inflammatory bowel disease.

BACKGROUND AND AIMS: SCENIC (International Consensus Statement on Surveillance and Management of Dysplasia in IBD) guidelines recommend that visible dysplasia in patients with longstanding inflammatory bowel disease (IBD) should be endoscopically characterized using a modified Paris classification. This study aimed to determine the interobserver agreement (IOA) of the modified Paris classification and endoscopists' accuracy for pathology prediction of IBD visible lesions. METHODS: One hundred deidentified endoscopic still images and 30 videos of IBD visible colorectal lesions were graded by 10 senior and 4 trainee endoscopists from 5 tertiary care centers. Endoscopists were asked to assign 4 classifications for each image: the standard Paris classification, modified Paris classification, pathology prediction, and lesion border. Agreement was measured using Light's kappa coefficient. Consensus of ratings was assessed according to strict majority. RESULTS: The overall Light's kappa for all study endpoints was between .32 and .49. In a subgroup analysis between junior and senior endoscopists, Light's kappa continued to be less than .6 with a slightly higher agreement among juniors. Lesions with the lowest agreement and no consensus were mostly classified as Is, IIa, and mixed Paris classification and sessile and superficial elevated for modified Paris classification. Endoscopist accuracy for prediction of dysplastic, nondysplastic, and serrated pathology was 77%, 56%, and 30%, respectively. There was a strong association (P < .001) between the given morphology classification and the predicted pathology with Ip lesions carrying a much lower expectation of dysplasia than Is/IIc/III and mixed lesions. The agreement for border prediction was .5 for junior and .3 for senior endoscopists. CONCLUSIONS: This study demonstrates very low IOA for Paris and modified Paris classifications and low accuracy and IOA for lesion histopathology prediction. Revisions of these classifications are required to create a clinically useful risk stratification tool and enable eventual application of augmented intelligence tools.

Validation of stricture length, duration and obstructive symptoms as predictors for intervention in ileal stricturing Crohn's disease.

BACKGROUND: Risk factors for intervention in terminal ileal (TI) stricturing Crohn's disease (CD) are poorly defined. Novel and rigorous definitions for TI strictures recently became available. OBJECTIVE: We aimed to describe the rates of symptoms or need for endoscopic balloon dilation (EBD) or surgery as well as risk factors of progression in a well-defined stricturing CD cohort. METHODS: Consecutive adult patients with non-penetrating stricturing TI CD, as defined by centrally-read magnetic resonance enterography CONSTRICT criteria, were separated into a derivation and validation cohort. Clinical and imaging characteristics were collected following prespecified scoring conventions. Primary outcome was a composite endpoint of EBD or surgery ("intervention"). Multivariable analysis was performed. RESULTS: Eighty-six patients (48.8% female, median age 36 years) met selection criteria, 17.4% had prior EBD, 59.3% previously received biologics and 58.1% of strictures were anastomotic. Median follow-up was 63.4 [95% CI: 57, 68.9] months. In the derivation cohort, at 12 and 48 months, 26% and 45% of patients had intervention, respectively. Multivariable analysis showed obstructive symptoms (Hazard ratio [HR] 1.444; 95% CI 1.126-1.852), stricture duration (HR 0.974; 95% CI, 0.954-0.995) and length (HR 1.039; 95% CI, 1.011-1.069) predicted intervention. The concordance index for split-sample validation was 0.74 and 0.67, respectively. Biologics were not associated with intervention. An online risk calculator was constructed. CONCLUSION: In patients with TI stricturing CD, 26% and 45% required intervention at 1 and 4 years. Obstructive symptoms, stricture duration and length were independent and validated predictors of the need for intervention. These findings are important for clinical practice and aid in the design of future trials for CD strictures.

Imaging Evaluation of Inflammatory Bowel Disease Complications.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that can progress to fibrostenotic and penetrating complications. Cross-sectional imaging is often needed for accurate diagnosis of IBD complication and for planning the appropriate management strategy. Computed tomography enterography, magnetic resonance enterography, and IBD ultrasound have become key tools for clinicians and interventional endoscopists. This article highlights and discusses various radiologic imaging techniques and their application to the diagnosis and management of IBD complications.

Adaptive and Robust Vessel Quantification in Contrast-Free Ultrafast Ultrasound Microvessel Imaging.

The morphological features of vasculature in diseased tissue differ significantly from those in normal tissue. Therefore, vasculature quantification is crucial for disease diagnosis and staging. Ultrasound microvessel imaging (UMI) with ultrafast ultrasound acquisitions has been determined to have potential in clinical applications given its superior sensitivity in blood flow detection. However, the presence of spatial-dependent noise caused by a low imaging signal-to-noise ratio and incoherent clutter artifacts caused by moving hyperechoic scatterers degrades the performance of UMI and the reliability of vascular quantification. To tackle these issues, we proposed an improved UMI technique along with an adaptive vessel segmentation workflow for robust vessel identification and vascular feature quantification. A previously proposed sub-aperture cross-correlation technique and a normalized cross-correlation technique were applied to equalize the spatially dependent noise level and suppress the incoherent clutter artifact. A square operator and non-local means filter were then used to better separate the blood flow signal from residual background noise. On the de-noised ultrasound microvessel image, an automatic and adaptive vessel segmentation method was developed based on the different spatial patterns of blood flow signal and background noise. The proposed workflow was applied to a CIRS phantom, to a Doppler flow phantom and to an inflammatory bowel, kidney and liver, to validate its feasibility. Results revealed that automatic adaptive, and robust vessel identification performance can be achieved using the proposed method without the subjectivity caused by radiologists/operators.