Koichi Takada

Unusual imaging appearances of pancreatic serous cystadenoma: correlation with surgery and pathologic analysis

BackgroundWe describe imaging and pathologic features of serous cystadenoma of the pancreas on multislice helical computed tomography CT (MS-CT) and surgical resection.MethodsRadiologic and pathologic features were analyzed in five patients. All patients underwent MS-CT and digital subtraction angiography (DSA), and four patients underwent magnetic resonance (MR) imaging. Preoperatively, three cases showed radiologic evidence of mainly solid appearance on MS-CT, and the suspected diagnoses were solid pancreatic tumors (patients 1–3). The other two cases showed radiologic evidence of macrocystic tumor of the pancreas, and the suspected diagnoses were mucinous cystic tumors (cases 4 and 5). All patients underwent surgery, and the diagnosis of serous cystadenoma was confirmed on pathologic examination.ResultsIn three cases that showed a solid appearance on MS-CT, a microcystic appearance was identified on microscopic examination, and the tumors were found to be hypervascular lesions on multiphasic contrast-enhanced CT and DSA. In cases 1 and 2, the lesions showed high intensity with internal septation on T2-weighted MR images. In two cases, the tumors were classified as a macrocystic variant of serous cystadenoma, and no mural nodules, papillary projections, or calcifications were seen in the tumors.ConclusionImaging appearance of serous cystadenoma on MS-CT is various and sometimes indistinguishable from that of solid tumor or mucinous cystic tumors of the pancreas. Imaging findings of hypervascularity and a well-marginated high-intensity lesion with internal septation on T2-weighted MR imaging may be crucial to identify serous cystadenoma that contains no visible cystic compartments on MS-CT.

Differential diagnosis of benign or malignant intraductal papillary mucinous neoplasm of the pancreas by multidetector row helical computed tomography: evaluation of predictive factors by logistic regression analysis.

Objective: The purpose of this study is to evaluate predictive factors for discriminating benign from malignant intraductal mucin-producing neoplasm (IPMN) of the pancreas on multidetector row computed tomography (MDCT). Materials and Methods: Fifty-three patients with IPMN underwent MDCT, and the imaging and pathological findings were evaluated. In patients with branch duct-type tumors, sex and age of the patient, location, shape, size and multiplicity of the cystic lesion, presence of mural nodule, and maximum diameter of main pancreatic duct (MPD) dilatation were evaluated by logistic regression analysis. Results: Tumors were classified as main duct-type (n = 7) and branch duct-type (n = 46). Among main duct-type tumors, all 7 lesions were diagnosed as malignant. Among 46 lesions of branch-type IPMN, 8 lesions were malignant, and 38 lesions were benign. On adjusted logistic regression analysis, combination factor of main duct dilatation and mural nodule or large cystic size had statistical significance for the risk of malignancy in branch duct-type IPMN. Conclusions: Main duct-type IPMN is highly suggestive for malignancy. Combination factors of main ductal dilation and mural nodule, and main ductal dilation, and large cystic tumor size are thought to be predictive factors for malignant branch-type IPMN.

Effect of superparamagnetic iron oxide-enhanced MRI of the liver with hepatocellular carcinoma and hyperplastic nodule.

Purpose To evaluate the possibility of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) of the liver in predicting the histologic grade of hepatocellular carcinoma (HCC) and differentiating HCC from benign hyperplastic nodule (HPN). Materials and Methods Thirty patients with 31 histologically proved HCC and HPN underwent MRI (1.5 Tesla). HCCs were graded into well-differentiated HCC (HCCw; n = 10) and moderately to poorly differentiated HCC (HCCmp; n = 15). HPN was categorized into dysplastic nodule (DN; n = 1) and focal nodular hyperplasia (FNH; n = 6). T2-weighted fast spin echo images were obtained before and after administration of SPIO. Signal-to-noise ratios (SNR) of the lesion and surrounding liver parenchyma and contrast-to-noise ratios (CNR) were calculated pre- and postcontrast study. Relative enhancement ratios (RER), also known as signal intensity reduction ratios of the lesions, were also calculated. Results HCCw, HCCmp, DN, and FNH decreased in SNR after injection of SPIO. RER of HCCw was 19.5 ± 13.3%, that of HCCmp was 6.8 ± 5.8%, DN was 44.0%, and FNH was 42.9 ± 4.8%. Significant statistical differences were seen between HCCw and HCCmp and HCC and HPN in RER. HCCw, HCCmp, and DN increased in CNR, and FNH decreased in CNR, but no lesion showed a statistically significant difference in CNR. Conclusion SPIO-enhanced MR images may help to predict the histologic grade of HCC and distinguish HCC from HPN.

Three cases of collagenous fibroma with rim enhancement on postcontrast T1-weighted images with fat suppression

Collagenous fibroma, also known as desmoplastic fibroblastoma, is a benign fibrous soft tissue tumor showing gradual growth, commonly without aggressive local infiltration. Today, preoperative radiological diagnosis is important to avoid over-treatment and unnecessary extensive procedures, but is difficult because diagnostic imaging findings for collagenous fibroma have not been established. We report MR imaging findings of three collagenous fibromas in correlation with their histopathology. The characteristic rim enhancement on post-contrast T1-weighted images with fat suppression was present in all three cases, and we consider this to represent the difference in vascularity between the outer capsule-like fibrous tissue and the inside of the tumor.

Chondromyxoid fibroma of the rib with prominent exophytic configuration

Chondromyxoid fibroma (CMF) of the rib is exceedingly unusual and few detailed image findings have been reported. Plain radiograph, computed tomography (CT), and magnetic resonance (MR) imaging findings and pathological aspects of a case of CMF of the right 2nd rib in a 15-year-old woman are reported, which was difficult to diagnose preoperatively. Though it is challenging to diagnose CMF preoperatively, it is important to be aware that CMF can exhibit atypical prominent exophytic features in unexpected locations such as the ribs.