Gastrointestinal Bleeding at CT Angiography and CT Enterography: Imaging Atlas and Glossary of Terms.

Gastrointestinal (GI) bleeding is a common potentially life-threatening medical condition frequently requiring multidisciplinary collaboration to reach the proper diagnosis and guide management. GI bleeding can be overt (eg, visible hemorrhage such as hematemesis, hematochezia, or melena) or occult (eg, positive fecal occult blood test or iron deficiency anemia). Upper GI bleeding, which originates proximal to the ligament of Treitz, is more common than lower GI bleeding, which arises distal to the ligament of Treitz. Small bowel bleeding accounts for 5-10% of GI bleeding cases commonly manifesting as obscure GI bleeding, where the source remains unknown after complete GI tract endoscopic and imaging evaluation. CT can aid in identifying the location and cause of bleeding and is an important complementary tool to endoscopy, nuclear medicine, and angiography in evaluating patients with GI bleeding. For radiologists, interpreting CT scans in patients with GI bleeding can be challenging owing to the large number of images and the diverse potential causes of bleeding. The purpose of this pictorial review by the Society of Abdominal Radiology GI Bleeding Disease-Focused Panel is to provide a practical resource for radiologists interpreting GI bleeding CT studies that reviews the proper GI bleeding terminology, the most common causes of GI bleeding, key patient history and risk factors, the optimal CT imaging technique, and guidelines for case interpretation and illustrates many common causes of GI bleeding. A CT reporting template is included to help generate radiology reports that can add value to patient care. An invited commentary by Al Hawary is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Relationship between Lower Dose and Injection Speed of Iodinated Contrast Material for CT and Acute Hypersensitivity Reactions: An Observational Study.

BackgroundThere are few data on the relationship between acute hypersensitivity reactions and the dose and injection rate of iodinated contrast material for CT.PurposeTo determine the relationship between lower dose and injection speed of iodinated contrast material for CT and the rate of acute hypersensitivity reactions.Materials and MethodsThis retrospective study included adults (age ≥18 years) undergoing nonionic iodinated contrast material-enhanced abdominal CT between August 2016 and January 2017 (control period) and between August 2017 and January 2018 (intervention period); all examinations were conducted in an outpatient setting. Compared with CT during the control period, CT during the intervention period involved a reduced dose of contrast material achieved by lowering the CT tube voltage. CT examinations in the control period were performed with 120 kVp, a contrast material dose of 2 mL/kg (maximum, 150 mL), and an injection speed of 3 or 4 mL/sec. CT examinations in the intervention period were performed with 100 kVp, a contrast material dose of 1.5 mL/kg (maximum, 130 mL), and an injection speed of 2.5 or 3 mL/sec. Per-examination rates of acute hypersensitivity reactions to iodinated contrast material were compared between the control and intervention periods with use of a multivariable Poisson regression model, the parameters of which were estimated by using generalized estimating equations with an independence correlation structure.ResultsA total of 21947 adults (mean age ± standard deviation, 59 years ± 12; 8797 women [40%]) underwent 25119 CT examinations during the control period; 23019 adults (mean age, 59 years ± 12; 9538 women [41%]) underwent 26491 CT examinations during the intervention period. The rate of acute hypersensitivity reactions was 1.42% (376 of 26491 examinations; 95% confidence interval [CI]: 1.28%, 1.57%) in the intervention period and 1.86% (468 of 25119 examinations; 95% CI: 1.70%, 2.04%) in the control period, with a multivariable-adjusted relative risk of 0.85 (95% CI: 0.74, 0.99; P = .03).ConclusionReduction in the dose and injection speed of iodinated contrast material for CT was associated with a lower rate of acute hypersensitivity reactions to iodinated contrast material.© RSNA, 2019Online supplemental material is available for this article.

Comparison of Radioembolization and Sorafenib for the Treatment of Hepatocellular Carcinoma with Portal Vein Tumor Thrombosis: A Systematic Review and Meta-Analysis of Safety and Efficacy.

OBJECTIVE: To compare the safety and efficacy of radioembolization with that of sorafenib for the treatment of hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT). MATERIALS AND METHODS: MEDLINE, EMBASE, and Cochrane databases were searched for studies reporting outcomes in patients with HCC and PVTT treated with radioembolization or sorafenib. Meta-analyses of cumulative overall survival (OS) and Kaplan-Meier survival rates according to the time to progression (TTP) and incidence of adverse events (AEs) were performed. Subgroup analyses were conducted on 1-year OS data. RESULTS: Seventeen studies were identified (four involving radioembolization, 10 involving sorafenib, and three comparing both). Pooled OS rates were higher in the radioembolization group, notably at 6 months {76% (95% confidence interval [CI], 64-85%) vs. 54% (95% CI, 45-62%)} and 1 year (47% [95% CI, 38-57%] vs. 24% [95% CI, 18-30%]); TTP was also longer with radioembolization. In patients undergoing radioembolization, the proportion of patients with Eastern Cooperative Oncology Group status 0 (p < 0.0001), Child-Pugh A (p < 0.0001), extrahepatic metastasis (p = 0.0012), and a history of cancer treatment (p = 0.0048) was identified as a significant source of heterogeneity for the 1-year OS. Radioembolization was associated with a lower incidence of grade 3/4 AEs than sorafenib (9% [95% CI, 3-27%] vs. 28% [95% CI, 17-43%]). CONCLUSION: Compared with sorafenib, radioembolization is a safer and more effective treatment for HCC with PVTT and is associated with prolonged survival, delayed tumor progression, and fewer grade 3/4 AEs.

Assessment by Using a Water-Soluble Contrast Enema Study of Radiologic Leakage in Lower Rectal Cancer Patients With Sphincter-Saving Surgery.

PURPOSE: This study evaluated the efficacy of a water-soluble contrast enema (WCE) in predicting anastomotic healing after a low anterior resection (LAR). METHODS: Between January 2000 and March 2012, 682 consecutive patients underwent a LAR or an ultra-low anterior resection (uLAR) and were followed up for leakage. Clinical leakage was established by using physical and laboratory findings. Radiologic leakage was identified by using retrograde WCE imaging. Abnormal radiologic features on WCE were categorized into four types based on morphology: namely, dendritic, horny, saccular, and serpentine. RESULTS: Of the 126 patients who received a concurrent diverting stoma, only two (1.6%) suffered clinical leakage due to pelvic abscess. However, 37 patients (6.7%) in the other group suffered clinical leakage following fecal diversion (P = 0.027). Among the 163 patients who received a fecal diversion, 20 showed radiologic leakage on the first WCE (eight with and 12 without a concurrent diversion); 16 had abnormal features continuously until the final WCE while four patients healed spontaneously. Eleven of the 16 patients (69%), by their surgeon's decision, underwent a stoma restoration based on clinical findings (2/3 dendritic, 3/4 horny, 5/7 saccular, 1/2 serpentine). After stoma reversal, only 2 of the 11 (19%) complained of complications related to the rectal anastomosis. CONCLUSION: WCE is helpful for detecting radiologic leakage before stoma restoration, especially in patients suffering clinical leakage after an uLAR. However, surgeons appear to opt for stoma restoration despite the persistent existence of radiologic leakage in cases with particular features on the WCE.

Diffusion-weighted MR enterography for evaluating Crohn's disease: how does it add diagnostically to conventional MR enterography?

BACKGROUND: Diffusion-weighted imaging (DWI) is a novel technique to evaluate bowel inflammation in Crohn's disease (CD). It is unknown whether and how DWI adds to the accuracy of conventional magnetic resonance enterography (MRE). METHODS: Fifty consecutive adults suspected of CD prospectively underwent clinical assessment, conventional MRE and DWI at b = 900 sec/mm without water enema, and ileocolonoscopy within 1 week. MRE images were interpreted with proper blinding. Forty-four patients finally diagnosed with CD (male:female, 34:10; 26.9 ± 6.1 yr) were analyzed. The per-segment accuracy of MRE for diagnosing active CD was assessed in the terminal ileum, right colon, and rectum using location-by-location matching with endoscopy as the reference standard. RESULTS: The study evaluated 58 bowel segments with deep or superficial ulcers, 34 with aphthae, erythema, or edema only, and 35 without inflammation. Conventional MRE + DWI was more sensitive for bowel inflammation than conventional MRE alone (83% [76/92] versus 62% [57/92]; P = 0.001) largely because of additional detection of aphthae, erythema, or edema. The sensitivities for deep and overt ulcers were similar regardless of DWI, ranging from 88% to 97%. Conventional MRE + DWI was less specific than conventional MRE alone (60% [21/35] versus 94% [33/35]; P < 0.001), mostly because of many false positives in the colorectum. Positive DWI findings in the bowel showing active inflammation on conventional MRE were associated with higher Crohn's disease endoscopic index of severity score (P = 0.021) and deep ulcers (P = 0.01; diagnostic odds ratio, 12). CONCLUSIONS: DWI performed without water enema is not useful for incremental detection of bowel inflammation. DWI may help identify more severe inflammation among bowel segments showing active inflammation on conventional MRE.

Comparison between CT colonography and double-contrast barium enema for colonic evaluation in patients with renal insufficiency.

OBJECTIVE: To compare the CT colonography (CTC) and double-contrast barium enema (DCBE) for colonic evaluation in patients with renal insufficiency. MATERIALS AND METHODS: Two sequential groups of consecutive patients with renal insufficiency who had a similar risk for colorectal cancer, were examined by DCBE (n = 182; mean ± SD in age, 51 ± 6.4 years) and CTC (n = 176; 50 ± 6.7 years), respectively. CTC was performed after colon cleansing with 250-mL magnesium citrate (n = 87) or 4-L polyethylene glycol (n = 89) and fecal tagging. DCBE was performed after preparation with 250-mL magnesium citrate. Patients with colonic polyps/masses of ≥ 6 mm were subsequently recommended to undergo a colonoscopy. Diagnostic yield and positive predictive value (PPV) for colonic polyps/masses, examination quality, and examination-related serum electrolyte change were retrospectively compared between the two groups. RESULTS: Both the CTC and DCBE were positive for colonic polyps/masses in 28 (16%) of 176 and 11 (6%) of 182 patients, respectively (p = 0.004). Among patients with positive findings, 17 CTC and six DCBE patients subsequently underwent a colonoscopy and yielded a PPV of 88% (15 of 17 patients) and 50% (3 of 6 patients), respectively (p = 0.089). Thirteen patients with adenomatous lesions were detected in the CTC group (adenocarcinoma [n = 1], advanced adenoma [n = 6], and non-advanced adenoma [n = 6]), as compared with two patients (each with adenocarcinoma and advanced adenoma) in the DCBE group (p = 0.003). Six (3%) of 176 CTC and 16 (9%) of 182 DCBE examinations deemed to be inadequate (p = 0.046). Electrolyte changes were similar in the two groups. CONCLUSION: In patients with renal insufficiency, CTC has a higher diagnostic yield and a marginally higher PPV for detecting colorectal neoplasia, despite a similar diagnostic yield for adenocarcinoma, and a lower rate of inadequate examinations as compared with DCBE.

Does the amount of tagged stool and fluid significantly affect the radiation exposure in low-dose CT colonography performed with an automatic exposure control?

OBJECTIVE: To determine whether the amount of tagged stool and fluid significantly affects the radiation exposure in low-dose screening CT colonography performed with an automatic tube-current modulation technique. METHODS: The study included 311 patients. The tagging agent was barium (n = 271) or iodine (n = 40). Correlation was measured between mean volume CT dose index (CTDI (vol)) and the estimated x-ray attenuation of the tagged stool and fluid (ATT). Multiple linear regression analyses were performed to determine the effect of ATT on CTDI (vol ) and the effect of ATT on image noise while adjusting for other variables including abdominal circumference. RESULTS: CTDI (vol) varied from 0.88 to 2.54 mGy. There was no significant correlation between CTDI (vol) and ATT (p = 0.61). ATT did not significantly affect CTDI (vol) (p = 0.93), while abdominal circumference was the only factor significantly affecting CTDI (vol) (p < 0.001). Image noise ranged from 59.5 to 64.1 HU. The p value for the regression model explaining the noise was 0.38. CONCLUSION: The amount of stool and fluid tagging does not significantly affect radiation exposure.

Alteration of functional neuroanatomy of simple object memory in medial temporal lobe epilepsy patients.

Using H2 15O PET, we examined the neuroanatomy associated with a simple form of episodic memory in patients with right or left medial temporal lobe epilepsy and normal healthy controls. When line drawings of common objects were memorized and tested after a 30 min delay, no behavioral difference was found between the patient groups and the controls. However, the patients with epilepsy showed greater cortical activations than the control group on the side ipsilateral to the epileptic focus. rCBF in the anterior thalamic region was enhanced in patients relative to the control group. The results showed that long-term dysfunction of the medial temporal lobe might reinforce alternative memory pathways and recruit a distributed cortical network ipsilateral to their epilepsy focus.