Complications of Mesh Sacrocolpopexy and Rectopexy: Imaging Review.

Sacrocolpopexy and rectopexy are commonly used surgical options for treatment of patients with pelvic organ and rectal prolapse, respectively. These procedures involve surgical fixation of the vaginal vault or the rectum to the sacral promontory with mesh material and can be performed independently of each other or in a combined fashion and by using an open abdominal approach or laparoscopy with or without robotic assistance. Radiologists can be particularly helpful in cases where patients' surgical histories are unclear by identifying normal sacrocolpopexy or rectopexy mesh material and any associated complications. Acute complications such as bleeding or urinary tract injury or stricture are generally evaluated with CT. More chronic complications such as mesh extrusion or exposure with or without fistulization to surrounding structures are generally evaluated with MRI. Other complications can have a variable time of onset after surgery. Patients with suspected bowel obstruction are generally evaluated with CT. Those with suspected infection, abscess formation, and discitis or osteomyelitis may be evaluated with MRI, although CT evaluation may be appropriate in certain scenarios. The authors review the sacrocolpopexy and rectopexy surgical techniques, discuss appropriate imaging protocols for evaluation of patients with suspected complications, and illustrate the normal appearance and common complications of these procedures. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

[The rôle of MRI in exploration anorectal pathologies]. / Place de l'IRM pour explorer les pathologies anorectales.

PLACE DE L'IRM POUR EXPLORER LES PATHOLOGIES ANORECTALES. L'imagerie par résonance magnétique (IRM) est l'un des examens d'imagerie les plus utiles à l'exploration des pathologies ano rectales. Elle est complémentaire de l'examen clinique et de l'endo scopie. Elle permet de fournir des données indispensables à une prise en charge optimale du patient par le proctologue, le chirurgien ou l'oncologue en fonction de la nature de l'atteinte anale ou rectale. Il est nécessaire de respecter les différentes indications de cet examen, qui ont été bien définies pour chaque pathologie par les différentes sociétés savantes. Le protocole de l'IRM varie en fonction de la zone explorée et de la pathologie suspectée. C'est pourquoi il est indispensable de fournir au radiologue les informations nécessaires telles que la suspicion diagnostique, les données cliniques, ainsi que les résultats des examens complémentaires déjà réalisés. Les indications les plus fréquentes de l'IRM en proctologie sont les tumeurs anales et rectales. L'IRM permet le bilan initial de l'extension locorégionale de la tumeur ainsi que le suivi oncologique précoce et tardif grâce à l'étude comparative des examens de surveillance par rapport au bilan initial. L'IRM est indispensable pour l'exploration des suppurations anopérinéales complexes, en particulier liées à la maladie de Crohn. Elle permet la réalisation du bilan lésionnel initial ainsi que le contrôle post-drainage. En cas de suspicion de maladie de Verneuil ou de sinus pilonidal infecté, l'IRM participe à l'orientation vers le diagnostic étiologique. La déféco-IRM est une variante particulière de l'IRM pelvienne et périnéale. Elle fait partie du bilan des dysfonctions du plancher pelvien, car elle permet l'étude du comportement des différents organes pelviens au cours des efforts de poussée et de défécation. Les fissures anales et les thromboses hémorroïdaires sont les causes les plus fréquentes de douleurs anales. Leur diagnostic est purement clinique. En cas d'examen proctologique normal, l'IRM sert à chercher une autre cause à ces douleurs.

THE ROLE OF MRI IN EXPLORATION ANORECTAL PATHOLOGIES. Magnetic resonance imaging (MRI) is one of the most useful imaging modalities for the exploration of anorectal pathologies. It is complementary to the clinical examination and endoscopy. It provides essential elements for optimal care of the patient by the proctologist, the surgeon or the oncologist depending on the nature of the anal or rectal condition. It is necessary to respect the different indications of this exam which have been well defined for each pathology by the different scientific societies. The MRI protocol varies depending on the site to be investigated and the pathology suspected. Therefore, it is essential to provide the radiologist with the necessary information such as the diagnostic suspicion, clinical findings, and the results of previous paraclinical examinations. MRI ensures the initial assessment of the locoregional extension of the tumor as well as the early and late oncological follow-up thanks to the comparative study of the surveillance examinations with the initial exam. MRI is essential for the assessment of complex anoperineal suppurations, in particular those related to Crohn's disease. It is necessary for the initial lesional assessment and for the post-drainage control. In case of suspicion of Verneuil's (hidradenitis suppurativa) disease or infected pilonidal sinus, MRI helps to orientate towards the right etiological diagnosis. MR defecating proctography is a particular variant of pelvic and perineal MRI. It is performed as part of the assessment of pelvic floor dysfunctions because it allows the study of the dynamics of the different pelvic organs during straining and defecation. Anal fissures and hemorrhoidal thrombosis are the most frequent etiologies of anal pain. Their diagnosis is purely clinical. If the proctological examination is normal, MRI is used to search for other causes of anal pain.

Adhesion-related small bowel obstruction: deep learning for automatic transition-zone detection by CT.

BACKGROUND: To train a machine-learning model to locate the transition zone (TZ) of adhesion-related small bowel obstruction (SBO) on CT scans. MATERIALS AND METHODS: We used 562 CTs performed in 2005-2018 in 404 patients with adhesion-related SBO. Annotation of the TZs was performed by experienced radiologists and trained residents using bounding boxes. Preprocessing involved using a pretrained model to extract the abdominopelvic region. We modeled TZ localization as a binary classification problem by splitting the abdominopelvic region into 125 patches. We then trained a neural network model to classify each patch as containing or not containing a TZ. We coupled this with a trained probabilistic estimation of presence of a TZ in each patch. The models were first evaluated by computing the area under the receiver operating characteristics curve (AUROC). Then, to assess the clinical benefit, we measured the proportion of total abdominopelvic volume classified as containing a TZ for several different false-negative rates. RESULTS: The probability of containing a TZ was highest for the hypogastric region (56.9%). The coupled classification network and probability mapping produced an AUROC of 0.93. For a 15% proportion of volume classified as containing TZs, the probability of highlighted patches containing a TZ was 92%. CONCLUSION: Modeling TZ localization by coupling convolutional neural network classification and probabilistic localization estimation shows the way to a possible automatic TZ detection, a complex radiological task with a major clinical impact.

Non-COVID-19 emergencies: where have all the patients gone?

KEY POINTS: • Early in the pandemic, numbers of patients undergoing non-COVID-19 emergent CTs dropped sharply but diagnostic yield did not increase, suggesting potentially undiagnosed emergencies in patients not seen in healthcare institutions.

CT diagnosis of closed loop bowel obstruction mechanism is not sufficient to indicate emergent surgery.

PURPOSE: To identify computed tomography (CT) findings associated with successful conservative treatment of closed loop small bowel obstruction (CL-SBO) due to adhesions or internal herniation. MATERIAL AND METHODS: The local institutional review board approved this study while waiving informed consent. Clinical and CT data were collected retrospectively for 96 consecutive patients with a CT diagnosis of CL-SBO due to adhesions or internal herniation established by experienced radiologists who had no role in patient management. Mechanical obstruction with at least two transition zones on the bowel at a single site defined CL-SBO. Two radiologists blinded to patient data independently performed a retrospective review of the CT scans. The patient groups with successful versus failed initial conservative therapy were compared. Univariate and multivariate analyses were performed to look for CT findings associated with successful conservative therapy. Interobserver agreement was assessed for each CT finding. RESULTS: Of the 96 patients, 34 (35%) underwent immediate surgery and 62 (65%) received first-line conservative treatment, which succeeded in 19 (31%) and failed in 43 (69%). The distance between the transition zones was the only independent predictor of successful conservative therapy (odds ratio, 4.6 when ≥ 8 mm; 95% confidence interval [95% CI], 1.2-18.3). A distance ≥ 8 mm had 84% (95% CI, 60-97) sensitivity and 46% (95% CI, 31-62) specificity for successful conservative treatment. The correlation coefficient for the distance between transition zones between readers 1 and 2 was fair (r = 0.46). CONCLUSION: CL-SBO can be resolved without surgery. When there is no CT sign of ischemia, the distance between the transition zones should be assessed. KEY POINTS: • Twenty percent (19/96) of all cases of closed loop small bowel obstruction (CL-SBO) representing 31% of the patients given first-line conservative therapy, were resolved without surgery. • The distance between the transition zones may help to choose between conservative and surgical management in patients with a CL-SBO but no CT evidence of ischemia. • A distance < 8 mm between the transition zones suggests a need for emergent surgery.

Initial Diagnosis and Staging of Pancreatic Cancer Including Main Differentials.

Computed tomography (CT) remains the optimal imaging modality for both diagnosis and staging of pancreatic adenocarcinoma. Especially, CT is highly accurate in assessing the relationship of the tumor to critical arterial and venous structures, since their involvement can preclude surgical resection or indicate a neoadjuvant strategy in borderline resectable or locally advanced lesions. MRI provides additional staging information in isodense tumors or regarding presence of small liver metastases not seen at CT. Endoscopic ultrasound is the reference technique to be used for obtaining histologic proof. The introduction of perfusion modalities and radiomics may benefit the evaluation of pancreatic lesion parameters, thus helping to rule out differentials. However, these techniques require further investigation and standardization.

Revised Atlanta classification for CT pancreatic and peripancreatic collections in the first month of acute pancreatitis: interobserver agreement.

PURPOSE: To assess interobserver agreement when using the revised Atlanta classification (RAC) to categorize pancreatic and peripancreatic collections during the first month of acute pancreatitis (AP), and to correlate type of collection to outcome. MATERIAL AND METHODS: This retrospective study of 115 consecutive patients admitted for 123 AP episodes, 178 CTs performed within the first month showed peripancreatic abnormalities. Each AP episode was classified as mild, moderately severe, or severe based on the RAC. Two radiologists, blinded to clinical data, used RAC criteria to retrospectively categorize the collections as acute peripancreatic fluid collections (APFC) or acute necrotic collections (ANC). Interobserver agreement was assessed based on Cohen's κ statistics and compared according to CT timing. RESULTS: Interobserver agreement for categorizing peripancreatic collections was moderate (κ = 0.45) and did not improve with time to CT (κ values, 0.53 < day 3, 0.34 on days 3-6, and 0.43 ≥ day 7). For detecting parenchymal necrosis, interobserver agreement was also moderate (κ = 0.45). AP was less severe in patients with APFC versus ANC (p = 0.04). CONCLUSION: Our finding of moderate interobserver agreement when using the RAC to categorize pancreatic and peripancreatic collections by CT indicates that the accurate diagnosis of APFC or ANC by CT in the first 4 weeks after symptom onset is often challenging. KEY POINTS: • Interobserver agreement was moderate for categorizing peripancreatic collections. • Interobserver agreement did not improve with time from onset to CT. • Interobserver agreement was moderate for detecting parenchymal necrosis.

Increased unenhanced bowel-wall attenuation: a specific sign of bowel necrosis in closed-loop small-bowel obstruction.

OBJECTIVES: To identify computed tomography (CT) findings associated with bowel necrosis in patients with surgically confirmed strangulating closed-loop small-bowel obstruction (CL-SBO) due to adhesions or internal hernia. METHODS: This retrospective study was approved by our institutional review board, and informed consent was waived. To identify CT signs of bowel necrosis, two gastrointestinal radiologists performed blinded, independent, retrospective reviews of 41 CT studies from consecutive patients who had CL-SBO due to adhesions or internal hernias and who underwent surgery within 48 h. On the basis of surgical and pathological findings, patients were classified as having reversible ischemia or histologically documented necrosis. Univariate statistical analyses were performed to assess associations between CT signs and bowel necrosis. Kappa statistics were computed to assess interobserver agreement. RESULTS: We included 25 (61%) women and 16 (39%) men with a median age of 79 years. Bowel necrosis was found in 25/41 (61%) patients and ischemic but viable bowel in 16/41 (39%) patients. Increased unenhanced bowel-wall attenuation was the only CT finding significantly associated with bowel necrosis (p = 0.0002). This sign had 58% (95% CI, 37-78) sensitivity and 100% (95% CI, 79-100) specificity for necrosis. Interobserver agreement was fair (0.59; 95% CI, 0.37-0.82). CONCLUSION: Increased unenhanced bowel-wall attenuation is specific for bowel necrosis and should lead to prompt surgery for bowel resection. KEY POINTS: • Increased unenhanced bowel-wall attenuation is the only sign specific for necrosis • Decreased bowel-wall enhancement is not relevant for differentiating reversible ischemia from necrosis • Preoperative knowledge of bowel necrosis is helpful to plan adequate surgery.

Acute Jejunoileal Diverticulitis: Multicenter Descriptive Study of 33 Patients.

OBJECTIVE: Acute jejunoileal diverticulitis is a very rare and potentially serious disease affecting mostly elderly patients. The diagnosis is based on imaging but remains underrecognized. The purpose of this study is to describe the clinical and CT features and the outcomes of patients with acute jejunoileal diverticulitis. MATERIALS AND METHODS: Cases of acute jejunoileal diverticulitis managed at three French hospitals November 2005 through January 2015 were identified retrospectively. The final diagnosis relied either on a clinical and radiologic data review by a panel of experts or on surgical findings. Demographic, clinical, laboratory, and 18-month outcome data were collected. CT scans were reviewed by two radiologists who reached a consensus about the presence of an inflammatory diverticulum, evidence of complications, and presence of other bowel diverticula. RESULTS: We identified 33 cases of acute jejunoileal diverticulitis in 33 patients with a median age of 78 years, including 30 (91%) patients in whom an inflammatory diverticulum was identified at the jejunum (n = 26, 87%) or ileum (n = 4, 13%). Extraintestinal gas was seen in 10 (30%) patients and extraintestinal fluid in 11 (33%) patients. Other small-bowel diverticula were visible in all 33 patients. The diverticulitis was mild and resolved with nonoperative treatment in 22 (67%) patients and was severe in the remaining 11 (33%) patients, eight of whom required emergent surgery. CONCLUSION: Acute jejunoileal diverticulitis is a rare and usually nonserious condition that chiefly involves the jejunum. A detailed CT assessment may allow nonoperative treatment.

Reduced dose CT with model-based iterative reconstruction compared to standard dose CT of the chest, abdomen, and pelvis in oncology patients: intra-individual comparison study on image quality and lesion conspicuity.

PURPOSE: To compare image quality and lesion conspicuity of reduced dose (RD) CT with model-based iterative reconstruction (MBIR) compared to standard dose (SD) CT in patients undergoing oncological follow-up imaging. METHODS: Forty-four cancer patients who had a staging SD CT within 12 months were prospectively included to undergo a weight-based RD CT with MBIR. Radiation dose was recorded and tissue attenuation and image noise of four tissue types were measured. Reproducibility of target lesion size measurements of up to 5 target lesions per patient were analyzed. Subjective image quality was evaluated for three readers independently utilizing 4- or 5-point Likert scales. RESULTS: Median radiation dose reduction was 46% using RD CT (P < 0.01). Median image noise across all measured tissue types was lower (P < 0.01) in RD CT. Subjective image quality for RD CT was higher (P < 0.01) in regard to image noise and overall image quality; however, there was no statistically significant difference regarding image sharpness (P = 0.59). There were subjectively more artifacts on RD CT (P < 0.01). Lesion conspicuity was subjectively better in RD CT (P < 0.01). Repeated target lesion size measurements were highly reproducible both on SD CT (ICC = 0.987) and RD CT (ICC = 0.97). CONCLUSIONS: RD CT imaging with MBIR provides diagnostic imaging quality and comparable lesion conspicuity on follow-up exams while allowing dose reduction by a median of 46% compared to SD CT imaging.

Right colonic diverticulitis in Caucasians: presentation and outcomes versus left-sided disease.

PURPOSE: To compare clinical features, computed tomography (CT) findings, and outcomes of right vs. left colonic diverticulitis (CD) in Caucasians. METHODS: This single-center retrospective case-control study of patients seen between July 2005 and February 2013 included 30 consecutive cases of right CD and 70 controls taken at random from a consecutive cohort of patients with left CD. The final diagnosis was established by consensus between a gastrointestinal surgeon and a gastrointestinal radiologist. Clinical features, treatment, and follow-up data were collected. Two radiologists blinded to patient data reached a consensus about multiple CT criteria. Cases and controls were compared using appropriate statistical tests, and odds ratios (ORs) associated with clinically meaningful variables were computed using univariate logistic regression. RESULTS: Median age was significantly lower in cases than in controls (48.5 years [IQR, 31-61] vs. 63.5 years [54-75], P < 0.0001). A body mass index <20 kg/m2 compared to >30 kg/m2 was associated with a higher risk of right than of left CD (OR 22.7, 95% confidence interval [95% CI], 2.6-200, P = 0.005). Compared to controls, cases more often had CT evidence of focal diverticular inflammation (86.7% [26/30] vs. 50% [35/70], P = 0.0006) and noncircumferential (≤180°) colonic wall thickening (66.7% [20/30] vs. 20% [14/70], P < 0.001). Complications were less common in the cases (6.7% [2/30] vs. 25.7% [18/70] than in controls, P = 0.03). CONCLUSION: In Caucasians, right CD occurs in younger and thinner patients and carries a lower risk of complications compared to left CD. Focal diverticular inflammation by CT is more common in right than in left CD.

Assessment of Bowel Wall Enhancement for the Diagnosis of Intestinal Ischemia in Patients with Small Bowel Obstruction: Value of Adding Unenhanced CT to Contrast-enhanced CT.

Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia, a complication of mechanical SBO, on the basis of decreased bowel wall enhancement. (©) RSNA, 2016.

Seminal vesicle metastasis of cutaneous malignant melanoma: An unusual and challenging presentation.

Malignant melanoma is a tumour, which usually involves skin melanocytes. Involvement of the male genitourinary (GU) system by melanoma is an uncommon and challenging diagnosis. We report the first case of seminal vesicle metastasis from a primary cutaneous melanoma in a 58-year-old man, with hemospermia as the only clinical sign. This case highlights the role of multiparametric magnetic resonance imaging, as a more sensitive assessment to early detect metastatic melanoma in the GU system. The patient underwent a robot-assisted laparoscopic bilateral seminal vesiculectomy, which had good functional and oncological results and is still in complete remission at the 1-year follow-up.

Anastomotic leakage after colorectal surgery: diagnostic accuracy of CT.

OBJECTIVES: To evaluate the diagnostic accuracy of CT in postoperative colorectal anastomotic leakage (AL). METHODS: Two independent blinded radiologists reviewed 153 CTs performed for suspected AL within 60 days after surgery in 131 consecutive patients, with (n = 58) or without (n = 95) retrograde contrast enema (RCE). Results were compared to original interpretations. The reference standard was reoperation or consensus (a radiologist and a surgeon) regarding clinical, laboratory, radiological, and follow-up data after medical treatment. RESULTS: AL was confirmed in 34/131 patients. For the two reviewers and original interpretation, sensitivity of CT was 82 %, 87 %, and 71 %, respectively; specificity was 84 %, 84 %, and 92 %. RCE significantly increased the positive predictive value (from 40 % to 88 %, P = 0.0009; 41 % to 92 %, P = 0.0016; and 40 % to 100 %, P = 0.0006). Contrast extravasation was the most sensitive (reviewers, 83 % and 83 %) and specific (97 % and 97 %) sign and was significantly associated with AL by univariate analysis (P < 0.0001 and P < 0.0001). By multivariate analysis with recursive partitioning, CT with RCE was accurate to confirm or rule out AL with contrast extravasation. CONCLUSIONS: CT with RCE is accurate for diagnosing postoperative colorectal AL. Contrast extravasation is the most reliable sign. RCE should be performed during CT for suspected AL. KEY POINTS: • CT accurately diagnosed clinically suspected colorectal AL and showed good interobserver agreement • Contrast extravasation was the most sensitive and specific CT sign • Retrograde contrast enema during CT improved positive predictive value • Retrograde contrast enema decreased false-negative or indeterminate original CT interpretations.

Pancreatic adenocarcinoma: MRI conspicuity and pathologic correlations.

PURPOSE: To identify the MRI sequences producing the greatest pancreatic adenocarcinoma conspicuity and to assess correlations linking MRI signal intensity and apparent diffusion coefficient to histopathological findings. METHODS: We retrospectively included 22 patients with pancreatic adenocarcinoma who underwent MRI (1.5 or 3 T) before surgical resection. Fat-suppressed (FS) T1- and T2-weighted sequences; 3D FS dynamic T1-weighted gadolinium-enhanced gradient-echo (GRE) imaging at the arterial, portal, and delayed phases; and diffusion-weighted imaging (DWI) with b values of 600-800 s/mm(2) were reviewed. On each sequence, we assessed tumor conspicuity both qualitatively (3-point scale) and quantitatively (tumor-to-proximal and -distal pancreas contrast ratios), and we performed paired Wilcoxon tests to compare these data across sequences. We evaluated correlations between histopathological characteristics and MRI features. RESULTS: 21/22 (95%) tumors were hypointense by 3D FS T1 GRE arterial phase imaging, which produced the greatest tumor conspicuity (p ≤ 0.02). By DWI, 5/20 (25%) of tumors were isointense. The correlation between size by histology and MRI was strongest with DWI. A progressive enhancement pattern was associated with extensive and dense fibrous stroma (p ≤ 0.03). CONCLUSIONS: 3D FS T1 GRE arterial phase imaging produces greater pancreatic adenocarcinoma conspicuity compared to DWI but underestimates tumor size. DWI provides the best size evaluation but fails to delineate the tumor in one-fourth of cases.

Hepatic and perihepatic involvement of female genital diseases and pregnancy: a review.

The liver is rarely involved in female genital diseases or pregnancy. Peripheral hepatic and perihepatic lesions are mainly due to the progression of genital malignancies, usually ovarian cancer. It should be distinguished from other malignant and non-malignant lesions. In all clinical situations, liver involvement is a sign of distant extension or dissemination of female genital diseases. Therefore, accurate detection and characterization of hepatic and perihepatic involvement on imaging is of clinical importance and often changes patient management.

Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction.

PURPOSE: To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard. MATERIALS AND METHODS: The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30-100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ(2) tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement. RESULTS: In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308). CONCLUSION: Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent.

Liver T2-weighted MR imaging: assessment of a three-dimensional fast spin-echo with extended echo train acquisition sequence at 1.5 Tesla.

PURPOSE: To retrospectively compare image quality and lesion detectability with two T2-weighted sequences at 1.5 Tesla (T): respiratory-triggered three-dimensional fat sat fast-spin-echo with extended echo-train acquisition (3D FSE-XETA) and respiratory-triggered two-dimensional fat-sat fast recovery fast-spin-echo (2D FRFSE). MATERIALS AND METHODS: MR was performed at 1.5T in 53 consecutive patients. Two radiologists blinded to the sequence details reviewed the studies to determine: (i) signal and contrast to noise ratios, (ii) overall image quality, (iii) sensitivity for focal lesion detection. RESULTS: Image assessment scores for the 2D FRFSE sequence were significantly higher than those for the 3D FSE-XETA sequence for overall image quality (P < 0.01) and artifacts (P < 0.001). Sensitivity for liver lesion detection was higher with the 3D FSE-XETA sequence (69.3% versus 57.3%; P < 0.05) compared with the 2D FRFSE sequence. The 3D FSE-XETA sequence improves the reader confidence score (P < 0.01) for liver lesions detection. Inter-observer correlation was higher with the 3D FSE-XETA sequence. CONCLUSION: For T2-weighted liver imaging at 1.5T, the 3D FSE-XETA sequence improves sensitivity, reader confidence score and interobserver correlation for focal liver lesion detection, but it suffers from a lower overall image quality and higher artifacts.

Multidetector CT angiography in acute gastrointestinal bleeding: why, when, and how.

Acute gastrointestinal (GI) bleeding remains an important cause of emergency hospital admissions, with substantial related morbidity and mortality. Bleeding may relate to the upper or lower GI tract, with the dividing anatomic landmark between these two regions being the ligament of Treitz. The widespread availability of endoscopic equipment has had an important effect on the rapid identification and treatment of the bleeding source. However, the choice of upper or lower GI endoscopy is largely dictated by the clinical presentation, which in many cases proves misleading. Furthermore, there remains a large group of patients with negative endoscopic results or failed endoscopy, in whom additional techniques are required to identify the source of GI bleeding. Multidetector computed tomography (CT) with its speed, resolution, multiplanar techniques, and angiographic capabilities allows excellent visualization of both the small and large bowel. Multiphasic multidetector CT allows direct demonstration of bleeding into the bowel and is helpful in the acute setting for visualization of the bleeding source and its characterization. Thus, multidetector CT angiography provides a time-efficient method for directing and planning therapy for patients with acute GI bleeding. The additional information provided by multidetector CT angiography before attempts at therapeutic angiographic procedures leads to faster selective catheterization of bleeding vessels, thereby facilitating embolization. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105206/-/DC1.

CT findings of misleading features of colonic diverticulitis.

Colonic diverticulitis (CD) is a common entity whose diagnosis is particularly based on computed tomography (CT) examination, which is the imaging technique of choice. However, unusual CT findings of CD may lead to several difficulties and potential pitfalls: due to technical errors in the management of the CT examination, due to the anatomical situation of the diseased colon, in diagnosing unusual complications that may concern the gastrointestinal tract, intra- and retroperitoneal viscera or the abdominal wall, and in differentiating CD from other abdominal inflammatory and infectious conditions or colonic cancer. The aim of this work is to delineate the pitfalls of CT imaging and illustrate misleading CT features in patients with suspected CD.