Soon Jin Lee

Hypervascular Hepatocellular Carcinoma 1 cm or Smaller in Patients With Chronic Liver Disease: Characterization With Gadoxetic Acid–Enhanced MRI That Includes Diffusion-Weighted Imaging

OBJECTIVE The purpose of this study was to determine the finding most predictive for characterizing hypervascular hepatocellular carcinoma (HCC) measuring 1 cm or less at gadoxetic acid-enhanced MRI that includes diffusion-weighted images. MATERIALS AND METHODS In this retrospective study, between May 2008 and June 2009, 66 patients with 108 hypervascular HCCs 1 cm or smaller underwent gadoxetic acid-enhanced 3-T MRI that included diffusion-weighted images. The diagnosis of HCC was determined by surgical resection in 32 cases, percutaneous biopsy in three cases, or interval growth to larger than 1 cm on follow-up images in accordance with the American Association for the Study of Liver Diseases guidelines in 73 cases. MRI findings of HCC and 33 benign hypervascular lesions in a control group were analyzed by two radiologists in consensus. They based their assessments on the presence or absence of the following five findings: hyperintensity on T2-weighted images, hyperintensity on diffusion-weighted images with low b values, washout pattern, capsular enhancement, and hypointensity on gadoxetic acid-enhanced hepatobiliary phase images. The findings were compared by use of univariate and multivariate analyses. RESULTS No HCC with capsular enhancement was found. Fifty-seven HCCs (52.8%) had four findings, 36 (33.3%) had three, nine (8.3%) had two findings, and six (5.6%) had one finding. Univariate analysis showed significant differences between the HCC and control groups with respect to four findings (p < 0.0001). Multivariate analysis showed that hyperintensity on T2-weighted (p < 0.0001) and diffusion-weighted (p = 0.0081) images were statistically significant MRI findings for predicting HCC. CONCLUSION Hyperintensity on both T2- and diffusion-weighted images is helpful in the diagnosis of hypervascular HCC smaller than 1 cm in diameter.

Locally Advanced Rectal Cancer: Added Value of Diffusion-weighted MR Imaging for Predicting Tumor Clearance of the Mesorectal Fascia after Neoadjuvant Chemotherapy and Radiation Therapy

PURPOSE To evaluate the added value of diffusion-weighted (DW) imaging in combination with T2-weighted magnetic resonance (MR) imaging compared with T2-weighted imaging alone for predicting tumor clearance of the mesorectal fascia (MRF) after neoadjuvant chemotherapy and radiation therapy (CRT) in patients with locally advanced rectal cancer. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and informed consent was waived. Forty-five patients with rectal cancer with clinically suspected MRF invasion who underwent neoadjuvant CRT and subsequent surgery were enrolled. All patients underwent pre- and post-CRT 3.0-T rectal MR imaging with DW imaging. Two observers independently reviewed a set of T2-weighted images and a combined set of T2-weighted and DW images and rated them by using a five-point scale. Diagnostic performance was evaluated for each observer with receiver operating characteristic (ROC) curve analysis. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value (NPV) were assessed. The standard of reference was histopathologic findings in the surgical specimen. Pairwise comparison of the ROC curves was used to compare diagnostic performance between the two image sets; the McNemar test was used to compare accuracy, sensitivity, and specificity. RESULTS The diagnostic performance (area under the ROC curve [A(z)]) with respect to MRF tumor clearance of both observers improved significantly after additional review of DW images: A(z) improved from 0.770 to 0.918 (P = .017) for observer 1 and from 0.847 to 0.960 (P = .026) for observer 2. The diagnostic accuracy of DW combined with T2-weighted imaging (observer 1, 89% [40 of 45]; observer 2, 93% [42 of 45]), sensitivity (observer 1, 94% [31 of 33]; observer 2, 97% [32 of 33]) and NPV (observer 1, 82% [nine of 11]; observer 2, 91% [10 of 11]) were significantly higher than those of T2-weighted imaging alone (accuracy: observer 1, 40% [18 of 45], P < .001; observer 2, 69% [31 of 45], P = .022; sensitivity: observer 1, 21% [seven of 33], P < .001; observer 2, 67% [22 of 33], P = .002; NPV: observer 1, 30% [11 of 37], P = .013; observer 2, 45% [nine of 20], P = .025). Interobserver agreement of confidence levels was fair for T2-weighted imaging alone (κ = 0.212) but was excellent for the combined set of DW and T2-weighted images (κ = 0.880). CONCLUSION Adding DW imaging to T2-weighted imaging can improve the prediction of tumor clearance in the MRF after neoadjuvant CRT compared with T2-weighted imaging alone in patients with locally advanced rectal cancer.

Radiological Spectrum of Intraductal Papillary Tumors of the Bile Ducts

Papillary tumor of the bile duct is characterized by the presence of an intraductal tumor with a papillary surface comprising innumerable frondlike infoldings of proliferated columnar epithelial cells surrounding slender fibrovascular stalks. There may be multiple tumors along the bile ducts (papillomatosis or papillary carcinomatosis), which are dilated due to obstruction by a tumor per se, by sloughed tumor debris, or by excessive mucin. Radiologically, the biliary tree is diffusely dilated, either in a lobar or segmental fashion, or aneurysmally, depending on the location of the tumor, the debris, and the amount of mucin production. A tumor can be depicted by imaging as an intraductal mass with a thickened and irregular bile duct wall. Sloughed tumor debris and mucin plugs should be differentiated from bile duct stones. Cystically or aneurysmally, dilated bile ducts in mucin-hypersecreting variants (intraductal papillary mucinous tumors) should be differentiated from cystadenoma, cystadenocarcinoma and liver abscess.

Preoperative staging of rectal cancer: accuracy of 3-Tesla magnetic resonance imaging

The purpose of this study was to evaluate the accuracy of 3-Tesla magnetic resonance imaging (MRI) for the preoperative staging of rectal cancer. Thirty-five patients with a primary rectal cancer who underwent preoperative 3-T MRI using a phased-array coil and had a surgical resection were enrolled in the study group. Preoperatively, three experienced radiologists independently assessed the T and N staging. A confidence level scoring system was used to determine if there was any perirectal invasion, and receiver operating characteristic (ROC) curves were generated. The interobserver agreement was estimated using κ statistics. The overall accuracy rate of T staging for rectal cancer was 92%. The diagnostic accuracy was 97% for T1, 89% for T2 and 91% for T3, respectively. The predictive accuracy for perirectal invasion by the three observers was high (Az>0.92). The interobserver agreement for T staging was moderate to substantial. The overall sensitivity, specificity, and accuracy for the detection of mesorectal nodal metastases were 80%, 98%, and 95%, respectively. In conclusion, preoperative 3-T MRI using a phase-array coil accurately indicates the depth of tumor invasion for rectal cancer with a low variability.

Diagnostic accuracy and sensitivity of diffusion-weighted and of gadoxetic acid-enhanced 3-T MR imaging alone or in combination in the detection of small liver metastasis (≤ 1.5 cm in diameter).

Purpose:To compare the diagnostic accuracy and sensitivity of combined gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) with each imaging approach alone for detecting small hepatic metastases (⩽1.5 cm). Materials and Methods:Institutional review board approved this retrospective study and waived informed patient consent. Eighty-six patients with 179 liver metastases underwent liver MRI including unenhanced and gadoxetic acid-enhanced imaging and DWI at 3.0 T. Three image sets including unenhanced images—gadoxetic acid set (early dynamic and hepatocyte phase), DWI set, and the combined set—were analyzed independently and in consensus by 2 observers for detecting liver metastases using receiver operating characteristic analysis. Results:There was a tendency toward an increased diagnostic accuracy for the combined set (mean, 0.965) compared with that for each image set alone (mean, 0.911 for gadoxetic acid set; 0.926 for DWI set). The combined set showed better sensitivity (mean, 97.47%/95.0%: values on per-lesion/per-patient basis) than each imaging set alone (mean, 90.7%/83.7% for gadoxetic acid set; 91.6%/83.0% for DWI set) (P < 0.05) on both per-lesion basis and per-patient basis. All image sets showed similar positive predictive values. Conclusions:The combination of gadoxetic acid-enhanced MRI and DWI yielded better diagnostic accuracy and sensitivity in the detection of small liver metastasis than each magnetic resonance scan sequence alone.

The value of PET/CT for preoperative staging of advanced gastric cancer: Comparison with contrast-enhanced CT

AIM To date, no data are available on the use of PET/CT for preoperative staging of gastric cancer. We attempted to evaluate the value of PET/CT for preoperative staging of advanced gastric cancer, and to compare the use of PET/CT with contrast-enhanced CT (CECT). MATERIALS AND METHODS We analyzed PET/CT of 78 patients with surgically proven advanced gastric cancer who had undergone preoperative CECT. Qualitative analysis was conducted by assessing the presence of primary tumors and metastases with PET/CT and CECT. RESULTS Among 71 patients who underwent a gastrectomy, 69 primary tumors (93%) were diagnosed by PET/CT, while 64 primary tumors (90%) were detected by CECT (p=0.55). For regional lymph node metastasis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT vs. CECT were 41% vs. 25% (p=0.00019), 100% vs. 92% (p=0.31), 100% vs. 98% (p=0.46), 26% vs. 42% (p=0.14), and 51% vs. 72% (p=0.00089), respectively. CONCLUSION Overall, PET/CT showed comparable diagnostic performance to CECT in diagnosing primary tumors and regional lymph node metastases, though PET/CT was inferior to CECT for the sensitivity and accuracy in diagnosing regional lymph node metastases. Nevertheless, PET/CT would be useful when CECT findings were equivocal due to its high positive predictability.

Preoperative Staging of Rectal Cancer: Comparison of 3-T High-Field MRI and Endorectal Sonography

OBJECTIVE The aim of this study was to compare phased-array 3-T MRI and endorectal sonography in the preoperative staging of rectal cancer. MATERIALS AND METHODS During an 8-month period, 24 patients with rectal cancer underwent both 3-T MRI performed with phased-array coils and 7.5- to 10-MHz endorectal sonography in the 3 weeks before surgical resection. Three radiologists independently reviewed the MR and endorectal sonographic images. The histopathologic findings in resected specimens were used to evaluate the sensitivities and specificities of these techniques for invasion of the muscularis propria and perirectal tissue and for lymph node involvement. Receiver operating characteristic (ROC) analysis was used to compare the diagnostic accuracies of the techniques. RESULTS For muscularis propria invasion, the mean sensitivities of both MRI and endorectal sonography were 100%, and the mean specificities were 66.7% and 61.1%, respectively. The differences in the mean sensitivities and specificities were not statistically significant (p > 0.05 in each case). For perirectal tissue invasion, MRI and endorectal sonography had comparable sensitivities and specificities (91.1% vs 100%, 92.6% vs 81.5%; p > 0.05 in each case). They also had similar sensitivities and specificities for lymph node involvement (63.6% vs 57.6%, 92.3% vs 82.1%; p > 0.05 in each case). ROC curves for muscularis propria invasion and lymph node involvement showed no differences in diagnostic accuracy. The mean area under the ROC curve for endorectal sonography (A(Z) = 0.996) for perirectal tissue invasion, however, showed higher accuracy than that of MRI (A(Z) = 0.938, p = 0.028). CONCLUSION The sensitivity, specificity, and accuracy of 3-T MRI were similar to those of endorectal sonography for muscularis propria invasion and lymph node involvement, but for perirectal tissue invasion, 3-T MRI was less accurate than endorectal sonography.

Clinical diagnosis of primary epiploic appendagitis: Differentiation from acute diverticulitis

Background Primary epiploic appendagitis (PEA) is an uncommon cause of abdominal pain that occurs either from appendageal torsion or spontaneous thrombosis of an appendageal draining vein. Primary epiploic appendagitis is frequently misdiagnosed as either appendicitis or diverticulitis, depending on its location. Study Clinical and radiologic characteristics of 8 patients with PEA were retrospectively reviewed and compared with 18 patients with acute diverticulitis. Results Patients with PEA presented with lower abdominal pain of recent onset that was localized to the left (seven cases) and right (one case) lower quadrants. Well-localized tenderness without peritoneal irritation sign was usually the only physical finding. Blood tests were not significant. In acute diverticulitis, the pain was more evenly distributed throughout the lower abdomen and findings like nausea, fever, and leukocytosis were more frequently associated than in PEA. Computed tomography findings, such as pedunculated oval fatty mass with streaky densities connected to the serosal surface of the adjacent colon, can lead to the diagnosis of PEA. Symptoms of PEA were resolved within 1 week (mean, 4.7 days) without surgery. Conclusions When patients with very localized lower abdominal pain and tenderness do not have associated symptoms or laboratory abnormalities, a high index of suspicion for PEA and early radiologic examinations are required.

Transient subsegmental hepatic parenchymal enhancement on dynamic CT : A sign of postbiopsy arterioportal shunt

PURPOSE Our goal was to verify the correlation between the arterioportal shunt caused by liver biopsy injury and wedge-shaped early transient subsegmental parenchymal enhancement (TSPE) of the liver during helical dynamic CT. METHOD Twenty-one consecutive patients with suspected hepatic tumor underwent percutaneous needle biopsy. Helical dynamic CT scans at arterial, portal venous, and delayed phases were obtained before and after biopsy. CT images were reviewed for the presence of TSPE during the arterial phase of dynamic CT. Hepatic arteriograms were obtained in all patients and reviewed for the presence of arterioportal shunt. RESULTS Wedge-shaped TSPE was observed on postbiopsy CT in 8 (38%) of the 21 patients along the needle path. In all of these patients subsegmental arterioportal shunt was confirmed by hepatic angiograms. CONCLUSION Wedge-shaped TSPE is commonly observed along the biopsy needle path and is due to arterioportal shunt caused by biopsy.

The spectrum of benign esophageal lesions: imaging findings.

Benign esophageal lesions occur in various diseases. Barium studies are useful for the evaluation of mucosal surface lesions but provide little information about the extramucosal extent of disease. Computed tomography and magnetic resonance imaging, on the other hand, permit the assessment of wall thickness, mediastinal involvement, adjacent lymphadenopathy, and distant spread. In diseases such as fibrovascular polyps, duplication cysts, scleroderma, trauma, caustic esophagitis, hiatal hernia, esophageal diverticulum, achalasia, and paraesophageal varices, the findings of imaging studies are specific, obviating the need for further invasive diagnostic work-up. The advent of helical computed tomography and its volume data set allows the acquisition of multiplanar images, and magnetic resonance imaging is useful both for this and for tissue characterization. Thus, multiplanar cross-sectional imaging further extends the role of imaging modalities to the evaluation of benign esophageal lesions. Through an awareness of the multiplanar cross-sectional appearances of various benign esophageal lesions, the radiologist can play an important role in the detection, diagnosis, further diagnostic planning, and treatment of the diseases in which they occur.