Hee Sun Park

Preoperative evaluation of pancreatic cancer: comparison of gadolinium-enhanced dynamic MRI with MR cholangiopancreatography versus MDCT.

To determine the accuracy of magnetic resonance imaging (MRI) including dynamic imaging using three‐dimensional gradient‐echo (3D‐GRE) sequences and MR cholangiopancreatograpy (MRCP) compared with that of multidetector row CT (MDCT) with regard to resectability in pancreas cancer.

Ectopic Pancreas: CT Findings with Emphasis on Differentiation from Small Gastrointestinal Stromal Tumor and Leiomyoma

PURPOSE To describe the computed tomographic (CT) findings of ectopic pancreas and to identify the features that differentiate it from other similarly manifesting gastric submucosal tumors such as gastrointestinal stromal tumor (GIST) and leiomyoma, which are the most common gastrointestinal submucosal tumors. MATERIALS AND METHODS This retrospective study was approved by the institutional review board and did not require informed consent. CT images of pathologically proved ectopic pancreases (n = 14), GISTs (n = 33), and leiomyomas (n = 7) in the stomach and duodenum were retrospectively reviewed. Analysis of the CT findings included evaluation of the location, contour, growth pattern, border, enhancement pattern, and enhancement grade of the tumor, as well as the presence of surface dimpling, prominent enhancement of overlying mucosa, and low intralesional attenuation. The attenuation of each lesion, the long diameter (LD), the short diameter (SD), and the LD/SD ratio were measured. Among these findings, statistically significant variables were determined by using the chi(2) test (to compare the categoric variables), the Student t test (for quantitative analysis), and the receiver operating characteristic curve (to determine the optimal cutoff of the LD/SD ratio). RESULTS The typical location (prepyloric antrum and duodenum), endoluminal growth pattern, ill-defined border, prominent enhancement of overlying mucosa, and an LD/SD ratio of greater than 1.4 were found to be significant for differentiating ectopic pancreas from other tumors (P < .05 for each finding). When at least two of these five criteria were used in combination, the sensitivity and specificity for diagnosing ectopic pancreas were 100% (14 of 14) and 82.5% (33 of 40), respectively. When four of these criteria were used, a sensitivity of 42.9% and a specificity of 100% were achieved. CONCLUSION By using specific CT criteria, ectopic pancreas can be differentiated from small GIST or leiomyoma with a high degree of accuracy.

Targeted Sonography for Small Hepatocellular Carcinoma Discovered by CT or MRI: Factors Affecting Sonographic Detection

OBJECTIVE The purpose of this study was to evaluate the detection rate of targeted sonography for small (<or= 3 cm) hepatocellular carcinomas (HCCs) primarily discovered by CT or MRI and to assess factors affecting lesion visibility on targeted sonography. SUBJECTS AND METHODS Between October 2005 and April 2008, targeted sonography for small (<or= 3 cm) HCC was prospectively performed in cirrhotic patients. Targeted sonography was performed by a radiologist with knowledge of the size and location of the HCC. Invisible HCCs were compared with visible HCCs with regard to size, distance from the diaphragm, segmental location, subcapsular location, cause of liver cirrhosis, presence or absence of previous treatment, Child-Pugh class, and serum alpha-fetoprotein by using univariate and multivariate analyses. RESULTS A total of 93 consecutive patients (65 men and 28 women; mean age, 59 years) with 93 HCCs (mean size +/- SD, 1.8 +/- 0.6 cm) were enrolled in this study. Of those, 73 (78.5%) HCCs were visible on targeted sonography. The detection rate was 36.4% (4/11) for HCC <or= 1.0 cm, 77.6% (38/49) for HCC between 1.1 and 2.0 cm, and 93.9% (31/33) for HCC between 2.1 and 3.0 cm. In both univariate and multivariate analyses, the size of the tumor and distance between the tumor and the diaphragm were statistically significant factors affecting sonographic visibility. CONCLUSION The overall detection rate for small (<or= 3 cm) HCC on targeted sonography was 78.5%. Small size and subphrenic location of the tumor were two independent predictors of sonographic invisibility.

Quantitative CT color mapping of the arterial enhancement fraction of the liver to detect hepatocellular carcinoma.

PURPOSE To investigate the diagnostic value of quantitative determination and three-dimensional color mapping of the arterial enhancement fraction (AEF) of the liver for the detection of hepatocellular carcinoma (HCC). MATERIALS AND METHODS This retrospective study was approved by the institutional review board; informed consent was waived. Eighty-two patients (mean age, 56.2 years +/- 10.7 [standard deviation]), 69 men (mean age, 57.1 years +/- 10.0) and 13 women (mean age, 51.6 years +/- 13.6), were followed-up for HCC or liver cirrhosis by using available multiphasic multidetector computed tomographic (CT) scans. Quantitative AEF color maps (the ratio of the attenuation increment during the arterial phase to the attenuation increment during the portal venous phase) of the whole liver were created from routine CT images by using prototypic software. Three radiologists independently analyzed a multiphasic CT image set; 4 weeks later, to avoid any potential recall bias, they independently analyzed a combined image set of the quantitative color maps and the multiphasic CT images. The additional diagnostic value of the color mapping was evaluated by means of jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis. RESULTS The mean AEF of HCCs (75.6 +/- 13.3) was significantly higher than that of liver parenchyma (23.4 +/- 8.2) (P < .001). The average JAFROC figure of merit was 0.861 on the initial multiphasic CT image set. This increased to 0.933 on the second session with the combined image set (P < .05). The mean sensitivity for HCC detection increased from 71.7% with the multiphasic CT image set to 88.8% with the combined image set. CONCLUSION Quantitative color mapping of the AEF can increase the sensitivity and diagnostic performance of multiphasic multidetector CT for detecting HCC. Supplementamaterial:http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC1http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC2http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC3

Accuracy of MRI for predicting the circumferential resection margin, mesorectal fascia invasion, and tumor response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer

To evaluate the diagnostic accuracy of MRI for predicting the circumferential resection margin (CRM), mesorectal fascia (MRF) invasion, and the tumor response to neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer.

Gadoxetic acid disodium-enhanced magnetic resonance imaging for biliary and vascular evaluations in preoperative living liver donors: comparison with gadobenate dimeglumine-enhanced MRI.

To compare gadoxetic acid disodium (Gd‐EOB‐DTPA)‐enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine (Gd‐BOPTA)‐enhanced MRI in preoperative living liver donors for the evaluation of vascular and biliary variations.

MR Imaging in Patients with Suspected Liver Metastases: Value of Liver-Specific Contrast Agent Gadoxetic Acid

Objective To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance (MR) imaging with that of triple-phase multidetector-row computed tomography (MDCT) in the detection of liver metastasis. Materials and Methods Our institutional review board approved this retrospective study and waived informed consent. The study population consisted of 51 patients with hepatic metastases and 62 patients with benign hepatic lesions, who underwent triple-phase MDCT and gadoxetic acid-enhanced MRI within one month. Two radiologists independently and randomly reviewed MDCT and MRI images regarding the presence and probability of liver metastasis. In order to determine additional value of hepatobiliary-phase (HBP), the dynamic-MRI set alone and combined dynamic-and-HBP set were evaluated, respectively. The standard of reference was a combination of pathology diagnosis and follow-up imaging. For each reader, diagnostic accuracy was compared using the jackknife alternative free-response receiver-operating-characteristic (JAFROC). Results For both readers, average JAFROC figure-of-merit (FOM) was significantly higher on the MR image sets than on the MDCT images: average FOM was 0.582 on the MDCT, 0.788 on the dynamic-MRI set and 0.847 on the combined HBP set, respectively (p < 0.0001). The differences were more prominent for small (≤ 1 cm) lesions: average FOM values were 0.433 on MDCT, 0.711 on the dynamic-MRI set and 0.828 on the combined HBP set, respectively (p < 0.0001). Sensitivity increased significantly with the addition of HBP in gadoxetic acid-enhanced MR imaging (p < 0.0001). Conclusion Gadoxetic acid-enhanced MRI shows a better performance than triple-phase MDCT for the detection of hepatic metastasis, especially for small (≤ 1 cm) lesions.

CT Differentiation of cholangiocarcinoma from periductal fibrosis in patients with hepatolithiasis.

OBJECTIVE The objective of our study was to determine useful CT findings for differentiating cholangiocarcinoma from periductal fibrosis in patients with hepatolithiasis. MATERIALS AND METHODS CT images of 30 patients with hepatolithiasis and pathologically proven cholangiocarcinoma (n = 14) or periductal fibrosis (n = 16) were retrospectively reviewed. Helical CT scans were obtained before, 30 seconds after, and 65 seconds after the start of contrast material injection. Analysis of CT findings included evaluation for the presence of periductal soft-tissue density, bile duct wall thickening at the stricture site, ascites, portal vein obliteration, lymph node enlargement, and a duct stone; assessment of the degree of ductal dilatation; and evaluation of the enhancement pattern of periductal lesions, thickened ductal wall, and hepatic parenchyma. The CT attenuation coefficients of the thickened ductal wall and adjacent normal-looking bile duct were measured on images obtained during each phase. Among these findings, statistically significant variables were determined using the Fishers exact test and Students t test. Sensitivity and specificity values of the CT criteria were also calculated. RESULTS The presence of periductal soft-tissue density (p = 0.002), higher enhancement of the duct than adjacent bile duct on portal venous phase images (p = 0.008), ductal wall thickening (p = 0.026), portal vein obliteration (p = 0.031), and lymph node enlargement (p = 0.031) were found to be the significant findings for differentiating cholangiocarcinoma from fibrosis in patients with hepatolithiasis. When any two or more of these five criteria were used in combination, we could identify 100% of the patients with cholangiocarcinoma but only 12.5% of the patients with fibrosis. CONCLUSION Cholangiocarcinoma in patients with hepatolithiasis can be diagnosed using specific CT criteria.

Gadobutrol-enhanced, three-dimensional, dynamic MR imaging with MR cholangiography for the preoperative evaluation of bile duct cancer.

Purpose:To evaluate the diagnostic performance of 1.0-M gadobutrol-enhanced, 3-dimensional (3D), dynamic MR images with 3D-MR cholangiography (MRC) in the preoperative evaluation of bile duct cancer staging and resectability. Materials and Methods:Our institutional review board approved this retrospective study. Sixty patients (46 male, 14 female; mean age 65.9 years; range, 45–77 years) with surgically and pathologically proven bile duct cancers, were included in this study. Two gastrointestinal radiologists evaluated the biliary MR images, including 3D-MRC and gadobutrol-enhanced, dynamic images, using a 3D-gradient echo (GRE) technique, regarding the longitudinal tumor extent, vascular involvement of the bile duct cancer, lymph node metastasis, and tumor resectability. The results were compared with the surgical and pathology findings used as the reference standards. Results:The area under the receiver operating characteristic curve (Az) of the 2 reviewers was 0.95 and 0.93, respectively, for evaluation of the involvement of both secondary biliary confluences and 0.85 and 0.84, respectively, for assessment of the intrapancreatic duct. For determining the tumor resectability, the overall accuracy was 0.93 and 0.88, respectively, whereas for assessment of the vascular involvement, the Az values were 0.92 for reviewer 1 and 0.70 for reviewer 2 for the portal vein evaluation, and 0.99 for reviewer 1 and 0.76 for reviewer 2 for the hepatic artery evaluation. In the assessment of lymph node metastasis, the overall accuracy was approximately 0.77 for each reviewer. Conclusion:One-molar, gadobutrol-enhanced, dynamic imaging, using a 3D-GRE technique with isotropic 3D-MRC showed excellent diagnostic capability for assessing the longitudinal extent and tumor resectability of bile duct cancer, although it generally underestimated the tumor involvement of vessels and lymph nodes.

Differentiation of well-differentiated hepatocellular carcinomas from other hepatocellular nodules in cirrhotic liver: value of SPIO-enhanced MR imaging at 3.0 Tesla.

To determine the diagnostic value of superparamagnetic iron oxide (SPIO)‐enhanced MRI for the differentiation of well‐differentiated hepatocellular carcinomas (WD‐HCCs) from other hepatocellular nodules in cirrhotic liver.