Hyun Kwon Ha

Crohn Disease of the Small Bowel: Comparison of CT Enterography, MR Enterography, and Small-Bowel Follow-Through as Diagnostic Techniques

PURPOSE To prospectively compare the accuracy of computed tomographic (CT) and magnetic resonance (MR) enterography and small-bowel follow-through (SBFT) examination for detection of active small-bowel inflammation and extraenteric complications in patients with Crohn disease (CD). MATERIALS AND METHODS The institutional review board approved the study protocol; informed consent was obtained from all participants. Thirty-one consecutive patients who had CD or who were suspected of having CD underwent CT and MR enterography, SBFT, and ileocolonoscopy. Two independent readers reviewed CT and MR enterographic and SBFT images for presence of active terminal ileitis and extraenteric complications. Accuracy values of CT and MR enterography and SBFT for identification of active terminal ileitis were evaluated with the receiver operating characteristic method, with ileocolonoscopic findings as the reference standard. Sensitivity values of CT and MR enterography and SBFT for detection of extraenteric complications were compared by using the McNemar test, with results of imaging studies, surgery, and physical examination as reference standards. RESULTS The study population included 30 patients (17 men, 13 women; mean age, 29.0 years) with CD. Differences in areas under the receiver operating characteristic curves for CT enterography (0.900 and 0.894), MR enterography (0.933 and 0.950), and SBFT (0.883 and 0.928) for readers 1 and 2, respectively, in the detection of active terminal ileitis were not significant (P > .017). Sensitivity values for detection of extraenteric complications were significantly higher for CT and MR enterography (100% for both) than they were for SBFT (32% for reader 1 and 37% for reader 2) (P < .001). CONCLUSION Because MR enterography has a diagnostic effectiveness comparable to that of CT enterography, this technique has potential to be used as a radiation-free alternative for evaluation of patients with CD.

Gastric cancer by multidetector row CT: preoperative staging.

The role of computed tomography (CT) in the preoperative staging of gastric cancer, even if controversial, may be fundamental for evaluating the local extent and nodal involvement of the disease, especially in locally advanced cases. However, previous results of CT staging have not been satisfactory for predicting the invasive depth of the tumor or possible nodal metastases. Recently introduced multidetector row CT (MDCT) and three-dimensional (3D) imaging are expected to overcome the limitations in cancer staging by offering rapid and accurate information for space perception, detailed hemodynamics, and real-time 3D processing of volumetric data sets. In particular, virtual endoscopic imaging may be helpful for detecting early gastric cancer. In our experience, T and N stagings of gastric cancer were improved with 3D MDCT when using volume rendering and virtual endoscopic imaging compared with conventional axial two-dimensional (2D) CT (accuracy of T staging with 3D vs. 2D CT images, 84% vs. 77%; accuracy of N staging, 63% vs. 61% with 3D vs. 2D images, respectively). In particular, the detection rate of early gastric cancer was markedly increased up to 96% when using 3D MDCT. Therefore, we believe that 3D MDCT of the stomach may enhance the performance of CT in the preoperative evaluation of patients who have gastric cancer by offering easy early detection of lesions and accurate tumor staging through the 3D imaging process.

Differential Diagnosis of Benign and Malignant Intraductal Papillary Mucinous Tumors of the Pancreas: MR Cholangiopancreatography and MR Angiography

Objective To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy. Materials and Methods During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA. Results Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p < 0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p < 0.05), and the presence of mural nodules was more frequent (p < 0.001). Conclusion Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas.

A Prospective Comparison of Standard-Dose CT Enterography and 50% Reduced-Dose CT Enterography With and Without Noise Reduction for Evaluating Crohn Disease

OBJECTIVE The purpose of this study was to prospectively compare standard-dose CT enterography (CTE) and 50% reduced-dose CTE, obtained with and without an image noise reduction method, in the evaluation of Crohn disease. SUBJECTS AND METHODS Ninety-two patients (69 men and 23 women; mean age [± SD], 31.2 ± 9.5 years) with Crohn disease underwent CTE. Using a dual-source scanner equipped with a proprietary noise reduction method (iterative reconstruction in image space [IRIS]), three sets of CTE images were obtained: standard-dose filtered back projection (FBP) (i.e., weighted FBP), low-dose (i.e., 50% reduction) FBP, and low-dose IRIS CTE. Image noise was measured. Two independent radiologists evaluated subjective image quality (1 [worst] to 4 [best]) and findings of active Crohn disease in the terminal small-bowel segment, including mural hyperenhancement, thickening and stratification, comb sign, and increased perienteric fat attenuation (1 [definitely absent] to 5 [definitely present]). RESULTS The mean (± SD) volume CT dose index (CTDI(vol)) was 7.0 ± 0.9 mGy and 3.5 ± 0.5 mGy for standard-dose and low-dose CTE examinations, respectively. The mean (± SD) image noise for standard-dose FBP, low-dose FBP, and low-dose IRIS CTE was 10.6 ± 1.7 HU, 13.9 ± 2.1 HU, and 9.7 ± 1.7 HU, respectively (p < 0.001 for all comparisons). Both assessors found that image quality was poorer with low-dose (mean grade (± SD), 2.3 ± 0.4-2.7 ± 0.5) than in standard-dose (3 ± 0) CTE (p < 0.01), and one found that image quality was poorer with low-dose IRIS (2.3 ± 0.4) than with low-dose FBP (2.7 ± 0.5) CTE (p < 0.01). Low-dose (with or without IRIS) and standard-dose CTE showed ≥ 85% agreement (one-sided 95% CI ≥ 77%) in interpretation of bowel findings. CONCLUSION Low-dose CTE using 50% reduced-dose performed similarly to standard-dose CTE in identifying findings of enteric inflammation of Crohn disease. Although a noise reduction method markedly reduced image noise in half-dose examinations, its effect on image quality was not as great and was reader dependent.

Autoimmune pancreatitis: radiologic findings in 20 patients

BackgroundAutoimmune pancreatitis is a new clinical entity that is characterized by peculiar histopathologic and laboratory findings and by a dramatic clinical response to corticosteroid therapy. We evaluated the radiologic findings of autoimmune pancreatitis.MethodsComputed tomographic, magnetic resonance imaging, endoscopic retrograde cholangiopancreatographic, and ultrasonographic findings of 20 patients with autoimmune pancreatitis in our hospital between November 2000 and December 2003 were retrospectively reviewed regarding changes and ancillary findings in the pancreatic parenchyma, the main pancreatic duct, peripancreatic vessels, and distal common bile duct. In addition, follow-up images were reviewed for changes in any abnormality seen on the initial examinations.ResultsPancreatic parenchymal enlargement was invariably seen that was diffuse (n = 19) or focal (n = 1), with homogeneous contrast enhancement on computed tomography (n = 20) and magnetic resonance imaging (n = 15). Capsule-like rim enhancement was seen in six patients. There was focal (n = 18) or diffuse (n = 2) narrowing of the main pancreatic duct and it was usually multifocal (n = 17) in the former. Narrowing of the peripancreatic veins was seen in 14 patients. There was tapered (n = 15) or abrupt (n = 3) narrowing of the distal common bile duct in 18 patients, with contrast enhancement of the narrowed segment in eight. Invariably, changes in the pancreatic parenchyma, main pancreatic duct, peripancreatic vessels, and common bile duct were normalized on follow-up studies after steroid therapy.ConclusionIn this series, common radiologic findings of autoimmune pancreatitis were (a) diffuse pancreas enlargement, (b) multifocal narrowing of the main pancreatic duct, (c) narrowing of peripancreatic veins, and (d) tapered narrowing of the distal common bile duct with frequent contrast enhancement. These findings were usually reversible with steroid therapy.

Anatomic Variation in Intrahepatic Bile Ducts: an Analysis of Intraoperative Cholangiograms in 300 Consecutive Donors for Living Donor Liver Transplantation

Objective To describe the anatomical variation occurring in intrahepatic bile ducts (IHDs) in terms of their branching patterns, and to determine the frequency of each variation. Materials and Methods The study group consisted of 300 consecutive donors for liver transplantation who underwent intraoperative cholangiography. Anatomical variation in IHDs was classified according to the branching pattern of the right anterior and right posterior segmental duct (RASD and RPSD, respectively), and the presence or absence of the first-order branch of the left hepatic duct (LHD), and of an accessory hepatic duct. Results The anatomy of the intrahepatic bile ducts was typical in 63% of cases (n=188), showed triple confluence in 10% (n=29), anomalous drainage of the RPSD into the LHD in 11% (n=34), anomalous drainage of the RPSD into the common hepatic duct (CHD) in 6% (n=19), anomalous drainage of the RPSD into the cystic duct in 2% (n=6), drainage of the right hepatic duct (RHD) into the cystic duct (n=1), the presence of an accessory duct leading to the CHD or RHD in 5% (n=16), individual drainage of the LHD into the RHD or CHD in 1% (n=4), and unclassified or complex variation in 1% (n=3). Conclusion The branching pattern of IHDs was atypical in 37% of cases. The two most common variations were drainage of the RPSD into the LHD (11%) and triple confluence of the RASD, RPSD and LHD (10%).

Flat Colorectal Neoplasms: Definition, Importance, and Visualization on CT Colonography

OBJECTIVE We discuss the definition of flat colorectal neoplasms, their clinical importance, CT colonography (CTC) findings, techniques for better visualization on CTC, and diagnostic pitfalls of such lesions. CONCLUSION Flat lesions appear on CTC as plaque-shaped mucosal elevations with or without a central depression, thickened haustral folds, and nodular mucosal surfaces. The sensitivity and optimal techniques of CTC for the detection of flat lesions have not yet been established. Three-dimensional endoluminal fly-through may be helpful for lesion detection. Fecal tagging helps in the distinction of true flat lesions from feces. I.v. contrast enhancement and the review with intermediate soft-tissue window settings, although not routinely used for CTC, may also help lesion visualization.

Comparative analysis of radiofrequency ablation and surgical resection for colorectal liver metastases

Purpose To evaluate the comparative therapeutic efficacy of radiofrequency ablation (RFA) and hepatic resection for the treatment of colorectal liver metastasis (CRLM). Methods Between 1996 and 2008, 177 patients underwent RFA, 278 underwent hepatic resection and 27 underwent combination therapy for CRLM. Comparative analysis of clinical outcomes was performed including number of liver metastases, tumor size, and time of CRLM. Results Based on multivariate analysis, overall survival (OS) correlated with the number of liver metastases and the use of combined chemotherapy (P < 0.001, respectively). Disease-free survival (DFS) also correlated with the number of liver metastases (P < 0.001). In the 226 patients with solitary CRLM < 3 cm, OS and DFS rates did not differ between the RFA group and the resection group (P = 0.962 and P = 0.980). In the 70 patients with solitary CRLM ≥ 3 cm, DFS was significantly lower in the RFA group as compared with the resection group (P = 0.015). Conclusion The results indicate that RFA may be a safe alternative treatment for solitary CRLM less than 3 cm, with outcomes equivalent to those achieved with hepatic resection. A randomized controlled study comparing RFA and resection for patients with single small metastasis would help to determine the most efficient treatment modalities for CRLM.

CT analysis of intestinal obstruction due to adhesions : early detection of strangulation

We evaluated the CT of intestinal obstruction due to adhesions in 20 postoperative patients, with emphasis on early detection of strangulation. Ten patients with surgically proven strangulated obstruction (strangulation group) were compared with another ten patients (nonstrangulation group) in whom seven improved with conservative management and three had confirmed simple obstruction on surgical exploration. Beak-like luminal narrowing (“beak”) was the most common CT finding at the obstructed site in both groups. The CT findings that suggested strangulated obstruction were serrated beaks, mesenteric edema or vascular engorgement, and moderate to severe bowel wall thickening. In contrast, simple obstruction could be assumed when the beak was smooth, there were no mesenteric changes, and the bowel wall was normal or mildly thickened. Computed tomography is a useful tool for detecting strangulation in patients with postoperative adhesive intestinal obstruction.

Preoperative evaluation of gallbladder carcinoma: Efficacy of combined use of MR imaging, MR cholangiography, and contrast‐enhanced dual‐phase three‐dimensional MR angiography

To determine the efficacy of the combined use of magnetic resonance (MR) imaging, MR cholangiography (MRC), and MR angiography (MRA) in the preoperative evaluation of gallbladder carcinoma.