Computed tomography features and predictive findings of ruptured gastrointestinal stromal tumours.

OBJECTIVES: To evaluate the CT features of ruptured GISTs and factors that might be predictive of rupture through comparison with CTs taken prior to rupture and CTs of non-ruptured GIST. METHODS: Forty-nine patients with ruptured GIST and forty-nine patients with non-ruptured GIST matched by age, gender and location were included. Clinical data including pharmacotherapy were reviewed. The imaging features were analyzed. Prior CT obtained before rupture were evaluated. RESULTS: The most common location of ruptured GIST was small bowel with mean size of 12.1 cm. Ruptured GIST commonly showed wall defects, >40 % eccentric necrosis, lobulated shaped, air density in mass, pneumoperitoneum, peritonitis, hemoperitoneum and ascites (p < 0.001-0.030). Twenty-seven of 30 patients with follow up imaging received targeted therapy. During follow-up, thickness of the tumour wall decreased. Increase in size and progression of necrosis were common during targeted therapy (p = 0.017). Newly developed ascites, peritonitis and hemoperitoneum was more common (p < 0.001-0.036). CONCLUSION: Ruptured GISTs commonly demonstrate large size, >40 % eccentric necrosis, wall defects and lobulated shape. The progression of necrosis with increase in size and decreased wall thickness during targeted therapy may increase the risk of rupture. Rupture should be considered when newly developed peritonitis, hemoperitoneum, or ascites are noted during the follow-up. KEY POINTS: • Ruptured GISTs demonstrate large size, eccentric necrosis, wall defects, and lobulated shape. • Rupture should be considered when peritonitis or hemoperitoneum/adjacent hematoma newly appears. • Progression of necrosis with increase in size increases the risk of rupture.

Corrosive-Induced Carcinoma of Esophagus: Esophagographic and CT Findings.

OBJECTIVE: The purpose of this study was to evaluate the esophagographic and CT findings of corrosive esophageal cancer. MATERIALS AND METHODS: The records of all patients who presented with corrosive esophageal strictures at one institution between June 1989 and April 2015 were retrospectively identified. The search yielded the records of 15 patients with histopathologically proven esophageal cancer. Esophagograms (13 patients) and chest CT images (14 patients) were interpreted independently by two reviewers. Esophagographic findings included the location of tumor, morphologic type, presence and length of mucosal irregularity, presence of asymmetric involvement, and presence of rigidity. CT findings included presence and type of esophageal wall thickening, pattern of enhancement, presence of periesophageal infiltration, and presence of hilar or mediastinal lymphadenopathy. RESULTS: Esophagography showed that the tumor was involved with the stenotic portion in 10 of the 13 patients (76.9%). The most common morphologic feature was a polypoid mass, in 10 patients. In 12 patients (92.3%), mucosal irregularities were observed; the mean affected length was 4.92 cm. Asymmetric involvement and rigidity were observed in nine patients (69.2%). On CT scans, eccentric wall thickening was observed in 10 of the 14 patients (71.4%), homogeneous enhancement in nine (64.2%), and periesophageal infiltration in 11 (78.5%). CONCLUSION: Esophagography commonly shows corrosive esophageal cancer as a polypoid mass with long-segment mucosal irregularities at the stenotic portion, asymmetric involvement, and rigidity. CT shows eccentric esophageal wall thickening with homogeneous enhancement and periesophageal infiltration, which are suggestive of the development of malignancy in patients with corrosive esophageal strictures.

MR Enterography for the Evaluation of Small-Bowel Inflammation in Crohn Disease by Using Diffusion-weighted Imaging without Intravenous Contrast Material: A Prospective Noninferiority Study.

PURPOSE: To determine whether magnetic resonance (MR) enterography performed with diffusion-weighted imaging (DWI) without intravenous contrast material is noninferior to contrast material-enhanced (CE) MR enterography for the evaluation of small-bowel inflammation in Crohn disease. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for this prospective noninferiority study. Fifty consecutive adults suspected of having Crohn disease underwent clinical assessment, MR enterography, and ileocolonoscopy within 1 week. MR enterography included conventional imaging and DWI (b = 900 sec/mm(2)). In 44 patients with Crohn disease, 171 small-bowel segments that were generally well distended and showed a wide range of findings, from normalcy to severe inflammation (34 men, 10 women; mean age ± standard deviation, 26.9 years ± 6.1), were selected for analysis. Image sets consisting of (a) T2-weighted sequences with DWI and (b) T2-weighted sequences with CE T1-weighted sequences were reviewed by using a crossover design with blinding and randomization. Statistical analyses included noninferiority testing regarding proportional agreement between DWI and CE MR enterography for the identification of bowel inflammation with a noninferiority margin of 80%, correlation between DWI and CE MR enterography scores of bowel inflammation severity, and comparison of accuracy between DWI and CE MR enterography for the diagnosis of terminal ileal inflammation by using endoscopic findings as the reference standard. RESULTS: The agreement between DWI and CE MR enterography for the identification of bowel inflammation was 91.8% (157 of 171 segments; one-sided 95% confidence interval: ≥88.4%). The correlation coefficient between DWI and CE MR enterography scores was 0.937 (P < .001). DWI and CE MR enterography did not differ significantly regarding the sensitivity and specificity for the diagnosis of terminal ileal inflammation (P > .999). DWI and CE MR enterography concurred in the diagnosis of penetrating complications in five of eight segments. CONCLUSION: DWI MR enterography was noninferior to CE MR enterography for the evaluation of inflammation in Crohn disease in generally well-distended small bowel, except for the diagnosis of penetration.

Computed tomography findings for a gastric lymphoepithelioma-like carcinoma: How often does it present as a submucosal mass?

OBJECTIVES: To describe the anatomical location, size, tumour characteristics and morphology on CT of gastric lymphoepithelioma-like carcinoma (LELC) in order to determine the proportion of lesions that present as submucosal masses, and to review the clinicopathological findings. METHODS: This retrospective study reviewed CT images of 186 lesions from 178 patients with LELC. CT morphologies and other findings were also analyzed. Pathology and medical records were reviewed. A pathology slide review of the lesions that presented with submucosal masses was performed. RESULTS: Gastric LELC presenting as a submucosal mass was found in 9.1 %. The most common CT morphology was eccentric wall thickening (67.7 %). On the pathology review, 14/17 submucosal mass lesions (82.4 %) had a central ulceration. 105 lesions were T1/T2 stage (94.1 %), and N0 stage was diagnosed in 66.1 %. Fifty-six of 63 metastatic lymph nodes (LNs) (88.9 %) demonstrated homogeneous enhancement, regardless of size. Male predominance (85.4 %), upper stomach location (45.7 %) and multiplicity (4.5 %) were found. CONCLUSIONS: Gastric LELC presenting as a submucosal mass is only detected in a small portion of all patients, and the most common finding is eccentric wall thickening. Central ulceration and enlarged LNs with homogeneous enhancement are occasionally other features on CT. KEY POINTS: • LELCs as submucosal masses on CT were detected in only 9.1 %. • The most common CT finding was eccentric wall thickening (67.7 %). • Central ulceration and enlarged LNs with homogeneous enhancement might be seen.

Endoscopic Complete Remission of Crohn Disease After Anti-Tumor Necrosis Factor-α Therapy: CT Enterographic Findings and Their Clinical Implications.

OBJECTIVE: The purpose of this study was to describe the CT enterographic (CTE) findings after endoscopic complete remission (CR) of Crohn disease in patients treated with anti-tumor necrosis factor-α (anti-TNF-α) and the clinical implications of these findings. MATERIALS AND METHODS: The records of 27 patients with Crohn disease (14 men, 13 women; mean age, 28.4 ± 8.6 [SD] years) who achieved endoscopic (ileocolonoscopic) CR after anti-TNF-α therapy and underwent CTE both before therapy and at endoscopic CR were identified. Two readers independently assessed the frequencies and severities of mural and perienteric CTE abnormalities, generally regarded as active inflammatory findings, in the terminal ileum and colorectum in the endoscopic CR state and compared them with the corresponding findings before anti-TNF-α therapy. The association between the presence of CTE abnormalities in the face of endoscopic CR and patient outcome during subsequent follow-up was investigated. RESULTS: CTE abnormalities were present in the face of endoscopic CR in 11-18 (26-42%) of 43 bowel sections (18 terminal ileum, 25 colorectum), the most frequent being mural hyperenhancement (21-40%) followed by mural thickening (12-16%). Both findings were mild and unaccompanied by other findings. The frequency and severity of mural and perienteric CTE abnormalities were statistically significantly reduced at endoscopic CR compared with the pre-treatment state. Patients with (n = 10) and without (n = 17) CTE abnormalities at endoscopic CR did not significantly differ with respect to Crohn disease aggravation during subsequent follow-up periods averaging 27.4 and 28.5 months (0/10 versus 2/17, p = 0.516). CONCLUSION: More than one-fourth of bowel sections in endoscopic CR after anti-TNF-α therapy had residual CTE abnormalities, predominantly mild mural thickening or hyperenhancement. These findings may not have any clinical significance.

Use of liver magnetic resonance imaging after standard staging abdominopelvic computed tomography to evaluate newly diagnosed colorectal cancer patients.

OBJECTIVE: To investigate the impact of liver magnetic resonance imaging (MRI) in staging evaluation of newly diagnosed colorectal cancer patients. BACKGROUND: No clear guidelines regarding how to use liver MRI in evaluating newly diagnosed colorectal cancer. METHODS: We included 863 adults who had newly diagnosed colorectal cancer without concomitant malignancies and received portal-phase contrast-enhanced abdominopelvic computed tomography (CT). Patients who had diminutive indeterminate hypoattenuating ["too-small-to-characterize" (TSTC)] hepatic lesions without other suspicious/indeterminate findings (TSTC-liver-on-CT), metastasis-negative hepatic findings (negative-liver-on-CT), and hepatic lesions suspicious or indeterminate for metastasis excluding TSTC lesions as seen on CT were identified. Per-patient rate of hepatic metastasis unsuspected by CT and the diagnostic yield of liver MRI for such lesions were assessed. RESULTS: There were 261 TSTC-liver-on-CT patients, 464 negative-liver-on-CT patients, and 138 patients with suspicious hepatic findings on CT. Among TSTC-liver-on-CT patients, the rate of hepatic metastasis was 2.2% (5/230, excluding patients without follow-up) and the yield of liver MRI was 3% (3/96). Negative-liver-on-CT patients gave the MRI yield of 0% (0/94). Among negative-liver-on-CT patients, the rate of hepatic metastasis discovered within 6 months of curative surgery was 1.1% (4/350, excluding patients without follow-up) when the liver was cleared by negative CT alone and 2% (2/88, excluding patients without follow-up) when cleared also by negative MRI (P = 0.347). Among the patients who had suspicious hepatic findings on CT, the MRI yield was 25% (19/77). CONCLUSIONS: The diagnostic yield of liver MRI for hepatic metastasis was very low in newly diagnosed colorectal cancer patients who showed TSTC hepatic lesions or metastasis-negative hepatic findings on CT. Staging liver MRI is likely unnecessary for them.

Incremental value of liver MR imaging in patients with potentially curable colorectal hepatic metastasis detected at CT: a prospective comparison of diffusion-weighted imaging, gadoxetic acid-enhanced MR imaging, and a combination of both MR techniques.

PURPOSE: To prospectively compare diagnostic performance of diffusion-weighted (DW) imaging, gadoxetic acid-enhanced magnetic resonance (MR) imaging, both techniques combined (combined MR imaging), and computed tomography (CT) for detecting colorectal hepatic metastases and evaluate incremental value of MR for patients with potentially curable colorectal hepatic metastases detected with CT. MATERIALS AND METHODS: In this institutional review board-approved prospective study, with informed consent, 51 patients (39 men, 12 women; mean age, 62 years) with potentially resectable hepatic metastases detected with CT underwent liver MR, including DW imaging and gadoxetic acid-enhanced MR. Two independent readers reviewed DW, gadoxetic acid-enhanced, combined MR, and CT image sets to detect hepatic metastases. The figure-of-merit (FOM) value representing overall diagnostic performance, sensitivity, and positive predictive value (PPV) for each image set were analyzed by using free-response receiver operating characteristic analysis and generalized estimating equations. RESULTS: There were 104 hepatic metastases in 47 patients. The pooled FOM values, sensitivities, and PPVs of combined MR (FOM value, 0.93; sensitivity, 98%; and PPV, 88%) and gadoxetic acid-enhanced MR (FOM value, 0.92; sensitivity, 95%; and PPV, 90%) were significantly higher than those of CT (FOM value, 0.82; sensitivity, 85%; and PPV, 73%) (P < .006). The pooled FOM value and sensitivity of combined MR (FOM value, 0.92; sensitivity, 95%) was also significantly higher than that of DW imaging (FOM value, 0.82; sensitivity, 79%) for metastases (≤1-cm diameter) (P ≤ .003). DW imaging showed significantly higher pooled sensitivity (79%) and PPV (60%) than CT (sensitivity, 50%; PPV, 33%) for the metastases (≤1-cm diameter) (P ≤ .004). In 47 patients with hepatic metastases, combined MR depicted more metastases than CT in 10 and 14 patients, respectively, according to both readers. CONCLUSION: Gadoxetic acid-enhanced MR and combined MR are more accurate than CT in detecting colorectal hepatic metastases, have an incremental value when added to CT alone for detecting additional metastases, and can be routinely performed in patients with potentially curable hepatic metastases detected with CT.

Iohexol versus diatrizoate for fecal/fluid tagging during CT colonography performed with cathartic preparation: comparison of examination quality.

OBJECTIVE: We aimed to compare iohexol vs. diatrizoate as fecal/fluid tagging agents for computed tomography colonography (CTC) regarding examination quality. METHODS: Forty prospective patients (M:F = 23:17; 63 ± 11.6 years) received CTC using 50 mL (350 mgI/mL) oral iohexol for tagging. Forty other indication-matched, age-matched, and sex-matched patients who underwent CTC using 100 mL diatrizoate for tagging and otherwise the same technique, were retrospectively identified. Two groups were compared regarding overall examination quality, per-patient and per-segment scores of colonic bubbles (0 [no bubbles] to 5 [the largest amount]), and the volume, attenuation, and homogeneity (untagged, layered, and homogeneous) of the residual colonic fluid. RESULTS: The iohexol group demonstrated a greater amount of colonic bubbles than the diatrizoate group: mean per-patient scores ± SD of 1.2 ± 0.8 vs. 0.7 ± 0.6, respectively (p = 0.003); and rates of segments showing ≥ grade 3 bubbles of 12.9 % (85/659) vs. 1.6 % (11/695), respectively (p = 0.001). Residual colonic fluid amount standardized to the colonic volume did not significantly differ: 7.2 % ± 4.2 vs. 7.8 % ± 3.7, respectively (p = 0.544). Tagged fluid attenuation was mostly comparable between groups and the fluid was homogeneously tagged in 98.7 % (224/227) vs. 99.5 % (218/219) segments, respectively (p = 0.344). Iohexol caused more colonic bubbles when used during cathartic CTC. Otherwise, examination quality was similarly adequate with both iohexol and diatrizoate. KEY POINTS: • When used for tagging, iohexol caused significantly more colonic bubbles than diatrizoate. • The residual colonic fluid amount did not significantly differ between iohexol and diatrizoate. • The quality of fluid tagging was similarly adequate in both iohexol and diatrizoate.

Inflammatory fibroid polyps of the gastrointestinal tract: a 14-year CT study at a single institution.

PURPOSE: To investigate the computed tomography (CT) features of pathology-proven inflammatory fibroid polyps (IFPs) in the gastrointestinal tract. METHODS: This retrospective series study included 27 patients with pathology-proven IFPs in the stomach (n = 16), small (n = 9), and large (n = 2) intestine, who underwent contrast-enhanced CT. Two radiologists reviewed the CT images of the patients to determine in consensus the long diameter, shape, margin, contour, and growth pattern of the lesions, the presence of an ulcer and overlying mucosal hyperenhancement, the lesion enhancement patterns including the homogeneity and the degree of contrast enhancement, and the presence of intussusception and obstruction. The CT results and clinical data of the gastric and intestinal lesions were compared. RESULTS: The IFPs typically manifested as well-defined (89%), round or ovoid (81%), slightly lobulated-contoured (70%) masses with a purely endoluminal growth pattern (96%) and an overlying mucosal hyperenhancement (67%). Lesion homogeneity and the degree of contrast enhancement varied. The intestinal IFPs were significantly larger (3.5 vs. 2 cm), more symptomatic (82% vs. 19%), and more frequently associated with intussusception (73% vs. 0%) and obstruction (46% vs. 6%) than the gastric lesions (p ≤ 0.027). CONCLUSIONS: The characteristic CT features of IFPs were well-defined, round or ovoid, lobulated-contoured, and endoluminal masses with overlying mucosal hyperenhancement and various enhancement patterns. IFP should be included in the differential diagnosis of patients with a soft-tissue mass in the gastrointestinal tract, especially if a large endoluminal mass in the small intestine is accompanied by intussusception.

Heterotopic pancreas of the jejunum: associations between CT and pathology features.

PURPOSE: To investigate the computed tomography (CT) features of heterotopic pancreas of the jejunum (HPJ) and to assess their associations with HPJ pathology features. METHODS: In this retrospective series analysis, two radiologists reviewed the CT images of 17 patients with surgically proven HPJ in order to determine in consensus the location, long diameter, margin, shape, contour, and growth pattern of the lesions, the presence of a duct-like structure, the lesion enhancement patterns, including the homogeneity, and the degree of contrast enhancement compared with that of the main pancreas. The pathology features of the surgical specimens were reviewed and their associations with the CT features were assessed. RESULTS: On CT, the HPJs typically appeared as a small (<3 cm), well-defined, ovoid or flat-shaped mass in the proximal jejunum with multiple and tiny lobulations. The growth pattern varied and the duct-like structure was rarely visible. The HPJs mostly appeared to be homogeneous and exhibited hyper- or isoattenuation compared to the main pancreas in the arterial and portal phases. However, these enhancement patterns varied slightly depending on the microscopic composition of the lesions (i.e., acinar vs. ductal predominance). Most HPJs comprised histologically of large acini, some ducts, and small islet cells, and had ductal communication with the jejunum. CONCLUSIONS: HPJs typically manifested as small, well-defined, ovoid or flat-shaped, homogeneous, and well-enhancing masses with a microlobulated contour in the proximal jejunum on CT, and their enhancement patterns associated with their microscopic composition. The pathology features of HPJs generally mimic those of the normal pancreas.

Adenomatous neoplasia: postsurgical incidence after normal preoperative CT colonography findings in the colon proximal to an occlusive cancer.

PURPOSE: To determine the postoperative incidence of adenomatous neoplasia in the colon proximal to an occlusive colorectal cancer where preoperative computed tomographic (CT) colonography findings were normal. MATERIALS AND METHODS: Institutional review board approval, with a waiver of informed consent, was obtained. This observational study included patients with occlusive colorectal cancer who underwent preoperative CT colonography between April 2007 and March 2010 that revealed normal findings (ie, no lesions ≥ 6 mm) in the proximal colon and who underwent postoperative colonoscopy. The primary outcome was postoperative colonoscopic discovery of clinically relevant lesions (ie, nondiminutive [≥ 6 mm] adenomas, advanced adenomas, or cancers) in the proximal colon. The cumulative incidence of clinically relevant lesions in preoperatively normal proximal colon over the postsurgical follow-up time was analyzed by using the Kaplan-Meier method. RESULTS: The final cohort included 204 patients (102 men and 102 women; mean age, 57.3 years ± 11.3 [standard deviation]). At a total of 435 postoperative colonoscopies performed over a median follow-up of 29 months (range, 1-74 months), clinically relevant lesions were detected in the proximal colon in 30 patients: Nonadvanced adenomas were detected in 23 patients, and advanced adenomas were detected in seven patients. The cumulative incidence of clinically relevant adenomatous lesions in the preoperatively normal proximal colon 12 and 18 months after preoperative CT colonography was 8.1% (95% confidence interval [CI]: 3.9%, 12.2%) and 9.6% (95% CI: 5%, 14%), respectively. Clinically relevant adenomatous lesions found in the proximal colon within 18 months of preoperative CT colonography were nonadvanced adenomas in 10 of 15 patients. CONCLUSION: When the portion of the colon proximal to an occlusive cancer is devoid of nondiminutive lesions at preoperative CT colonography, colonoscopy of the proximal colon following cancer resection rarely finds clinically relevant lesions and is unlikely to reveal any lesions requiring immediate removal until routine 1-year postsurgical follow-up. Online supplemental material is available for this article .

Endoscopic and clinical analysis of primary T-cell lymphoma of the gastrointestinal tract according to pathological subtype.

BACKGROUND AND AIM: Little is known about the clinicopathological characteristics of primary gastrointestinal T-cell lymphomas (PGITL). This study evaluated the clinical and endoscopic features of the pathological subtypes of PGITL. METHODS: Forty-two lesions in 36 patients with PGITL were assessed, including 15 enteropathy-associated T-cell lymphomas (EATL), 13 peripheral T-cell lymphomas (PTCL), 10 NK/T-cell lymphomas (NK/TL), and four anaplastic large cell lymphomas (ALCL). RESULTS: PTCL occurred more frequently in the stomach and duodenum and NK/TL more frequently in the small and large intestines (P = 0.009). The endoscopic features of the four subtypes were similar (P = 0.124). Fifteen of 41 lesions (36.6%) were Epstein-Barr virus (EBV) positive, with NK/TL more likely to be EBV positive than the other types (P < 0.001). First endoscopy and first computed tomography (CT) scan indicated that 65.4% and 51.4% of the lesions, respectively, were malignant, and that 43.2% and 42.3%, respectively, were GI lymphomas. The two modalities together correctly diagnosed about half of the lesions before biopsy. Intestinal perforation was associated with small bowel location (P < 0.001) and infiltrative type (P = 0.009), and was more common in NK/TL than in the other subtypes (P = 0.015). Multivariate analysis showed that higher international prognosis index (P = 0.008) and the presence of complications (P = 0.006) were associated with poor prognosis. Survival was poorer in patients with small bowel lesions than with lesions at other locations (P = 0.048). CONCLUSIONS: The four main pathological types of PGITL differed in clinical characteristics. As PGITL was often not diagnosed by initial endoscopic or radiological examination, a high index of suspicion is necessary to ensure its early diagnosis.

Locally advanced rectal cancer: diffusion-weighted MR tumour volumetry and the apparent diffusion coefficient for evaluating complete remission after preoperative chemoradiation therapy.

OBJECTIVE: To evaluate DW MR tumour volumetry and post-CRT ADC in rectal cancer as predicting factors of CR using high b values to eliminate perfusion effects. METHODS: One hundred rectal cancer patients who underwent 1.5-T rectal MR and DW imaging using three b factors (0, 150, and 1,000 s/mm(2)) were enrolled. The tumour volumes of T2-weighted MR and DW images and pre- and post-CRT ADC150-1000 were measured. The diagnostic accuracy of post-CRT ADC, T2-weighted MR, and DW tumour volumetry was compared using ROC analysis. RESULTS: DW MR tumour volumetry was superior to T2-weighted MR volumetry comparing the CR and non-CR groups (P < 0.001). Post-CRT ADC showed a significant difference between the CR and non-CR groups (P = 0.001). The accuracy of DW tumour volumetry (Az = 0.910) was superior to that of T2-weighed MR tumour volumetry (Az = 0.792) and post-CRT ADC (Az = 0.705) in determining CR (P = 0.015). Using a cutoff value for the tumour volume reduction rate of more than 86.8 % on DW MR images, the sensitivity and specificity for predicting CR were 91.4 % and 80 %, respectively. CONCLUSION: DW MR tumour volumetry after CRT showed significant superiority in predicting CR compared with T2-weighted MR images and post-CRT ADC.

Uncommon gastrointestinal complications after liver transplantation: radiologic findings and clinical features.

There are various uncommon gastrointestinal complications, as liver transplantation becomes increasingly popular as the only curative method for patients with end-stage liver diseases. It is important for radiologists evaluating postoperative liver transplantation recipients to have a perspective on the possible gastrointestinal complications after liver transplantation and their radiologic features for early detection and early treatment. This article illustrates radiologic findings and clinical features of various uncommon gastrointestinal complications after liver transplantation.

CT colonography for detection and characterisation of synchronous proximal colonic lesions in patients with stenosing colorectal cancer.

OBJECTIVE: To investigate CT colonography (CTC) performance for detecting and characterising synchronous lesions proximal to a stenosing colorectal cancer and to suggest patient management strategies according to the CTC findings. METHODS: 411 consecutive patients underwent CTC for proximal colonic evaluation after failed colonoscopy past a newly diagnosed stenosing colorectal cancer. Pathological examination of colectomy specimen and/or postsurgical colonoscopy with pathological confirmation of the proximal synchronous lesions to serve as reference standards existed in 284 patients. Per-patient and per-lesion diagnostic performance measures of CTC for diagnosing proximal synchronous lesions ≥6 mm analysed by histopathological categories were obtained for the 284 patients. Per-lesion sensitivity and positive predictive value (PPV) of various CTC lesion size criteria and lesion size combined with other CTC findings for diagnosing cancer in the proximal colon were determined. RESULTS: Both per-patient and per-lesion CTC detection sensitivities for proximal synchronous cancers were 100% (6/6 patients and 8/8 lesions; 95% CI 64.3% to 100% and 70.7% to 100%, respectively) with the corresponding per-patient negative predictive value (NPV) of a negative CTC of 100% (194/194 patients; 95% CI 98.3% to 100%). Per-patient NPV of a negative CTC for advanced neoplasia (ie, advanced adenomas and colorectal cancers) was 97.4% (189/194 patients; 95% CI 93.9% to 99.1%). A lesion size ≥15 mm on CTC as the criterion to specifically diagnose proximal cancer yielded 87.5% (7/8 lesions; 95% CI 50.8% to 99.9%) per-lesion sensitivity, rendering one 8-mm submucosal cancer mischaracterised as a non-cancerous lesion, and 70% (7/10 lesions; 95% CI 39.2% to 89.7%) per-lesion PPV. Additional CTC findings did not improve the sensitivity. CONCLUSION: CTC is highly sensitive in detecting synchronous cancers proximal to a stenosing colorectal cancer. CTC has limited capability in differentiating advanced adenomas from colorectal cancer and this compromises the PPV of CTC for the presence of proximal cancer.

Diagnostic value of FDG-PET/CT for lymph node metastasis of colorectal cancer.

BACKGROUND: Lymph node metastasis is an important prognostic factor in patients with colorectal cancer. We assessed the ability of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) to diagnose lymph node metastases in colorectal cancer patients. METHODS: We retrospectively analyzed the records of 473 patients who underwent preoperative FDG-PET/CT, followed by curative surgery for colorectal cancer. Lymph node metastases were assessed as proximal or distal, depending on their anatomical location. We analyzed the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG-PET/CT and CT for detecting lymph node metastases. RESULTS: In detecting proximal lymph nodes, FDG-PET/CT had a sensitivity of 66 %, a specificity of 60 %, a PPV of 63 %, an NPV of 62 %, and an accuracy of 63 %; whereas CT had a sensitivity of 87 %, a specificity of 29 %, a PPV of 57 %, an NPV of 68 %, and an accuracy of 59 % (P = 0.245). FDG-PET/CT and CT also showed similar accuracy in detecting distal lymph nodes (87 vs. 88 %, P = 0.620). CONCLUSION: Preoperative FDG-PET/CT and CT have comparable accuracy in detecting lymph node metastases of colorectal cancer.

Obscure gastrointestinal bleeding: diagnostic performance of multidetector CT enterography.

PURPOSE: To evaluate the diagnostic performance of computed tomographic (CT) enterography in identifying the source of obscure gastrointestinal bleeding and to determine clinical features associated with a higher diagnostic yield of CT enterography. MATERIALS AND METHODS: The institutional review board approved this study, with waiver of informed consent. CT enterographic images in 65 patients (46 men [mean age, 54 years; range, 18-85 years] and 19 women [mean age, 62.1 years; range, 33-79 years]) who presented with obscure gastrointestinal bleeding between August 2005 and July 2007 were reviewed retrospectively and independently by two radiologists. The diagnostic performance of CT enterography was assessed by using the results of endoscopic and other imaging examinations, surgery, and clinical follow-up as the reference standard. Differences in the diagnostic yield of CT enterography according to patient demographic and clinical features, including age, sex, type and episode of bleeding (occult, initial overt, and recurrent overt), occurrence of recent bleeding, and history of massive bleeding, were evaluated by using univariate and multivariate logistic regression analyses. RESULTS: CT enterography helped identify the source of obscure gastrointestinal bleeding in 16 (24.6%) of 65 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of CT enterography were 55.2% (16 of 29), 100% (32 of 32), 100% (16 of 16), and 71.1% (32 of 45), respectively. Among patients' clinical features, a history of massive bleeding (diagnostic yield, 58.3% [seven of 12]; adjusted odds ratio, 7.2; P = .01) was independently associated with a higher diagnostic yield for CT enterography. CONCLUSION: CT enterography has a potential role in the evaluation of obscure gastrointestinal bleeding. Despite the limited sensitivity of CT enterography, positive CT enterographic findings can reliably indicate the true source of obscure gastrointestinal bleeding. CT enterography is particularly effective in helping identify the source of bleeding in patients with a history of massive bleeding. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101936/-/DC1.

Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: validation in phantoms and in patients with chronic liver disease.

PURPOSE: To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS-MRI) analysis methods and MR spectroscopy (MRS) with and without T2-correction in fat quantification in the presence of excess iron. MATERIALS AND METHODS: CS-MRI with six opposed- and in-phase acquisitions and MRS with five-echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS-MRI, FFs were estimated with the dual-echo method, with two T2*-correction methods (triple- and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2-correction (single-echo MRS) and with T2-correction (multiecho MRS). RESULTS: In the phantoms, T2*- or T2-correction methods for CS-MRI and MRS provided unbiased estimations of FFs (mean bias, -1.1% to 0.5%) regardless of iron concentration, whereas the dual-echo method (-5.5% to -8.4%) and single-echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple-echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual-echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit-of-agreement, -0.2 ± 1.1). CONCLUSION: T2*- or T2-correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS-MRI in fat quantification.

Ascending colon rotation following patient positional change during CT colonography: a potential pitfall in interpretation.

OBJECTIVE: To investigate the degree and pattern of ascending colonic rotation as patients moved from supine to prone positions during CTC. METHODS: A search of our CTC and colonoscopy database found 37 patients (43 eligible lesions) who fulfilled the following criteria: colonoscopy-proven sessile polyps ≥ 6 mm in the straight mid-ascending colon, lesion visualisation in both supine and prone CTC, and optimal colonic distension. A coordinate system was developed to designate the polyp radial location (°) along the luminal circumference, unaffected by rotation of the torso. The degree/direction of polyp radial location change (i.e. ascending colonic rotation) between supine and prone positions correlated with anthropometric measurements. RESULTS: Movement from supine to prone positions resulted in a change in the radial polyp location of between -23° and 79° (median, 21°), demonstrating external rotation of the ascending colon in almost all cases (2° to 79° in 36/37 patients and 42/43 lesions). The degree/direction of rotation mildly correlated with the degree of abdominal compression in the anterior-posterior direction in prone position (r = 0.427 [P = 0.004] and r = 0.404 [P = 0.007]). CONCLUSION: The ascending colon was usually found to rotate externally as patients moved from supine to prone positions, partly dependent on the degree of abdominal compression.

CT colonography in patients who have undergone sigmoid colostomy: a feasibility study.

OBJECTIVE: The purpose of this study was to evaluate the technical feasibility of CT colonography of patients who have undergone sigmoid colostomy after abdominoperineal resection. MATERIALS AND METHODS: Seven men and 11 women (mean age, 57.2 ± 14.5 [SD] years) who had undergone abdominoperineal resection with sigmoid colostomy for rectal cancer were included. Colonic cleansing and fecal tagging were performed with magnesium citrate and 5% weight/volume barium. A conventional small rectal catheter with a retention balloon was introduced into the colonic stoma. An inflated balloon (15-25 mL) was positioned several centimeters beneath the skin. The interposed tissue acted as the mechanism for preventing balloon expulsion during colonic insufflation with carbon dioxide. Unenhanced right decubitus and contrast-enhanced supine images were obtained. Air-fluid leak, balloon expulsion, complications, and colonic distention evaluated on a 4-point scale in which 1 was the worst and 4 the best and mucosal coverage were assessed. RESULTS: Examinations were performed uneventfully for all but one patient, who had temporary air and fluid leakage. The mean amount of carbon dioxide used was 2.64 ± 0.64 L. In the right decubitus position, the mean distention grade of each colonic segment was 2.7 ± 1.1 (sigmoid), 3.4 ± 0.6 (descending), 3.6 ± 0.5 (transverse), 3.6 ± 0.5 (ascending), and 3.7 ± 0.5 (cecum). In the supine position the mean grades were 2.7 ± 1.2, 3.1 ± 0.7, 3.7 ± 0.5, 3.7 ± 0.5, and 3.8 ± 0.4. Four patients (22.2%) had segments not adequately visualized in either position owing to luminal collapse; all of these segments were in the sigmoid colon. Three patients (16.7%) had areas submerged under fecal matter in both positions, but these areas were evaluable because of fecal tagging or IV contrast enhancement. CONCLUSION: CT colonographic examination through a sigmoid stoma was technically feasible with currently available instruments, but further improvements in technique are needed.