Heon-Ju Kwon

Prostate Cancer Detection on Dynamic Contrast-Enhanced MRI: Computer-Aided Diagnosis Versus Single Perfusion Parameter Maps

OBJECTIVE The purpose of this article is to assess the value of computer-aided diagnosis (CAD) for prostate cancer detection on dynamic contrast-enhanced MRI (DCE-MRI). MATERIALS AND METHODS DCE-MRI examinations of 42 patients with prostate cancer were used to generate perfusion parameters, including baseline and peak signal intensities, initial slope, maximum slope within the initial 50 seconds after the contrast injection (slope(50)), wash-in rate, washout rate, time to peak, percentage of relative enhancement, percentage enhancement ratio, time of arrival, efflux rate constant from the extravascular extracellular space to the blood plasma (k(ep)), first-order rate constant for eliminating gadopentetate dimeglumine from the blood plasma (k(el)), and constant depending on the properties of the tissue and represented by the size of the extravascular extracellular space (A(H)). CAD for cancer detection was established by comprehensive evaluation of parameters using a support vector machine. The diagnostic accuracy of single perfusion parameters was estimated using receiver operating characteristic analysis, which determined threshold and parametric maps for cancer detection. The diagnostic performance of CAD for cancer detection was compared with those of T2-weighted imaging (T2WI) and single perfusion parameter maps, using histologic results as the reference standard. RESULTS The accuracy, sensitivity, and specificity of CAD were 83%, 77%, and 77%, respectively, in the entire prostate; 77%, 91%, and 64%, respectively, in the transitional zone; and 89%, 89%, and 89%, respectively, in the peripheral zone. Values for k(ep), k(el), initial slope, slope(50), wash-in rate, washout rate, and time to peak showed greater area under the curve values (0.803-0.888) than did the other parameters (0.545-0.665) (p < 0.01) and were compared with values for CAD. In the entire prostate, accuracy was greater for CAD than for all perfusion parameters or T2WI (63-77%); sensitivity was greater for CAD than for T2WI, initial slope, wash-in rate, slope(50), and washout rate (38-77%); and specificity was greater for CAD than for T2WI, k(ep), k(el), and time to peak (59-68%) (p < 0.05). CONCLUSION CAD can improve the diagnostic performance of DCE-MRI in prostate cancer detection, which may vary according to zonal anatomy.

Peritoneal Mesotheliomas: Clinicopathologic Features, CT Findings, and Differential Diagnosis

OBJECTIVE The objective of our study was to illustrate various CT findings of peritoneal mesotheliomas, to review their clinicopathologic features, and to discuss the differential diagnoses. CONCLUSION The clinicopathologic features of peritoneal mesotheliomas vary among the subtypes such as malignant mesotheliomas, cystic mesotheliomas, and well-differentiated papillary mesotheliomas, and accordingly, there is a spectrum of CT appearances.

Solitary Fibrous Tumor of the Pancreas: Imaging Findings

We report here a case of a pathologically proven solitary fibrous tumor of the pancreas. A 54-year-old man was referred to our hospital for further evaluation of a pancreatic mass that was found incidentally. CT, MR imaging, and endoscopic ultrasonography showed a well-defined, enhancing mass with cystic portions of the pancreas body. MR cholangiopancreatography showed no pancreatic duct dilatation. A solitary fibrous tumor of the pancreas is a very rare lesion.

Simultaneous Bilateral Carotid Stenting in High-Risk Patients

BACKGROUND AND PURPOSE: The safety and efficacy of SBCAS have not been evaluated in detail. The purpose of our study was to evaluate the outcome after SBCAS in high-risk patients compared with unilateral stent placement. MATERIALS AND METHODS: Between March 2002 and October 2008, a total of 205 consecutive high-risk patients underwent CAS at our institution. Of these patients, 30 (14.6%) underwent SBCAS (n = 24) and staged SBCAS (n = 6). Patients who underwent unilateral CAS (n = 175) during the same period served as controls. The stroke risk factors, procedural results, and outcome at 30 days and 6 months, as well as the restenosis rate at 6 months, were compared by using either the χ2 test or the Kruskal-Wallis equality-of-populations rank test. RESULTS: Our data revealed no significant differences in the stroke risk factors between the SBCAS and the control group. HPS occurred more commonly in SBCAS (ie, 16.7%, 4/24) compared with 2.9% (5/175) in the control group (P = .014). However, there was no statistical significance between 2 groups in the event rate of stroke (minor and/or major stroke), death, or restenosis at 6 months. CONCLUSIONS: There was no significant difference in outcome at 6 months following stent placement between SBCAS and unilateral CAS in the high-risk patient group, even though HPS occurred more commonly after SBCAS.

Treatment Strategy Based on Multimodal Management Outcome of Cavernous Sinus Dural Arteriovenous Fistula (CSDAVF)

Purpose Angiographic finding including venous drainage pattern should be correlated to the presenting symptom pattern (SxP) in CSDAVF. We present outcome of CSDAVF management and suggest a strategy according to SxP and type of treatment based on our experience. Materials and Methods We evaluated SxP, angiographic type (proliferative, restrictive or late restrictive), mode of treatment (embolization, Gamma Knife Radiation (GKR) or conservative management), mode of embolization (transarterial or transvenous), and final clinical status (cure, improvement, aggravation or no change). Ninety consecutive patients were included from a prospective database. The mean follow-up was 17 months. We compared the outcomes according to SxP, angiographic type, mode of treatment, and embolization using the chi-square or Fishers exact test. Results Ninety patients with 34 proliferative, 40 restrictive, and 16 late restrictive types of CSDAVF were treated by embolization (n = 63), GKR (n = 7), and conservative management (n = 20). Cure or improvement was 91% after embolization, 88% after conservative management, and 72% after GKR. Following embolization, 100% of 24 proliferative types, 87% of 30 restrictive types, and 90% of 10 late restrictive types were cured or improved. Cure or improvement after transvenous embolization was 98% (43/44) compared with 88% (15/17) after transarterial embolization (p = 0.003). Conclusion Various factors of SxP, angiographic type, and mode of treatment should be considered in order to obtain a more favorable outcome for patients with CSDAVF. Embolization via venous approach tended to result in a more complete cure than that via arterial approach.

Pneumatosis intestinalis after liver transplantation.

PURPOSE To evaluate clinical features and CT findings of pneumatois intestinalis in recipients following liver transplantation and to determine whether certain clinical and CT findings enable differentiation of indolent pneumatois intestinalis from fulminant cases. MATERIALS AND METHODS This retrospective study was approved by our institutional review board, with informed consent waived. Among 2080 liver transplantation recipients at our institution between January 1998 and April 2008, 22 (1%) presented with pneumatois intestinalis on postoperative follow-up. Patients were divided into recovery and mortality groups, and then clinical features and CT findings were compared between two groups. RESULTS Although indolent pneumatois intestinalis more frequently presented incidentally (61%) after 2 weeks of surgery (89%) than fulminant pneumatois intestinalis (0, 50%), there were no statistically significant differences (P=.14, .09). Right colon was affected in the recovery group without exception (n=18,100%), and all four patients (100%) in mortality group showed small bowel involvement (P<.05). Caliber changes of superior mesenteric artery and vein in mortality group were significantly greater (49.6%, 67.0%) than those in recovery group (101.7%, 99.0%) (P<.05, respectively). Pneumatois intestinalis in mortality group more commonly accompanied portomesenteric air-embolism, visceral infarction, hemorrhagic ascites, and small bowel ileus than indolent counterpart (P<.05, respectively). CONCLUSION Typical indolent pneumatois intestinalis is found incidentally later than 2 weeks of liver transplantation surgery, but there is some overlap between indolent and fulminant pneumatois intestinalis in terms of onset and mode of presentation. Among CT findings, grave signs are small bowel involvement, caliber changes in mesenteric vessels, portomesenteric air-embolism, visceral infarction, hemorrhagic ascites, and small bowel ileus.

Value of the Ultrasound Attenuation Index for Noninvasive Quantitative Estimation of Hepatic Steatosis

To assess the value of the ultrasound (US) attenuation index for noninvasive estimation of hepatic steatosis and determine its optimal cutoff value for severe steatosis in potential living liver donors.

Complications in Living Liver Donors After Partial Liver Procurement: An Illustrative Radiologic Review

OBJECTIVE The purpose of this article is to present an illustrative radiologic review of the usual postoperative findings and of various postoperative complications in living liver donors. CONCLUSION Radiologic studies can reveal various complications in living liver donors after partial liver resection. Meticulous radiologic surveillance is mandatory for living liver donors during the early postoperative period because their safety is of primary concern in living donor liver transplantation.

Resection plane-dependent error in computed tomography volumetry of the right hepatic lobe in living liver donors

Background/Aims Computed tomography (CT) hepatic volumetry is currently accepted as the most reliable method for preoperative estimation of graft weight in living donor liver transplantation (LDLT). However, several factors can cause inaccuracies in CT volumetry compared to real graft weight. The purpose of this study was to determine the frequency and degree of resection plane-dependent error in CT volumetry of the right hepatic lobe in LDLT. Methods Forty-six living liver donors underwent CT before donor surgery and on postoperative day 7. Prospective CT volumetry (VP) was measured via the assumptive hepatectomy plane. Retrospective liver volume (VR) was measured using the actual plane by comparing preoperative and postoperative CT. Compared with intraoperatively measured weight (W), errors in percentage (%) VP and VR were evaluated. Plane-dependent error in VP was defined as the absolute difference between VP and VR. % plane-dependent error was defined as follows: |VP–VR|/W∙100. Results Mean VP, VR, and W were 761.9 mL, 755.0 mL, and 696.9 g. Mean and % errors in VP were 73.3 mL and 10.7%. Mean error and % error in VR were 64.4 mL and 9.3%. Mean plane-dependent error in VP was 32.4 mL. Mean % plane-dependent error was 4.7%. Plane-dependent error in VP exceeded 10% of W in approximately 10% of the subjects in our study. Conclusions There was approximately 5% plane-dependent error in liver VP on CT volumetry. Plane-dependent error in VP exceeded 10% of W in approximately 10% of LDLT donors in our study. This error should be considered, especially when CT volumetry is performed by a less experienced operator who is not well acquainted with the donor hepatectomy plane.

MR cholangiography in potential liver donors: quantitative and qualitative improvement with administration of an oral effervescent agent: MRC With Oral Effervescent Agent

To determine whether an oral effervescent agent improves magnetic resonance cholangiography (MRC) images, both qualitatively and quantitatively, in potential live liver donors.