Shuichi Monzawa

Dynamic CT for detecting small hepatocellular carcinoma: usefulness of delayed phase imaging.

OBJECTIVE The purpose of this retrospective study was to determine the usefulness of delayed phase imaging for detecting small (< or = 2 cm) hepatocellular carcinomas (HCCs) in patients with liver cirrhosis. MATERIALS AND METHODS Triphasic (arterial, portal venous, and delayed phases) dynamic CT was performed in 33 patients with 48 HCCs proven histopathologically and in 65 control subjects. Arterial, portal venous, and delayed phase images were obtained 30 seconds, 68-70 seconds, and 5 minutes after the start of contrast material injection, respectively. Three blinded observers reviewed the images independently and evaluated tumor attenuation. Diagnostic performance for the combination of phases was assessed using receiver operating characteristic (ROC) curve analysis. RESULTS On arterial phase images, 28 of the 48 HCCs were hyperattenuating, nine were isoattenuating, and 11 were hypoattenuating. On portal venous phase images, three tumors were hyperattenuating, 17 were isoattenuating, and 28 were hypoattenuating. On delayed phase images, five tumors were isoattenuating, and 43 were hypoattenuating. The mean sensitivity for the combination of arterial and portal venous phase imaging was 86.8%, that for the combination of arterial and delayed phase imaging was 90.3%, and that for the combination of all three phase imaging was 93.8%. The area underneath composite ROC curve (A(Z)) for the combination of all three phase imaging (A(Z) = 0.940) was significantly higher than that for the combination of arterial and portal venous phase imaging (A(Z) = 0.917) and for the combination of arterial and delayed phase imaging (A(Z) = 0.922). CONCLUSION Delayed phase imaging is useful for detecting small HCCs and should be included in dynamic CT examinations of patients with liver cirrhosis.

Mucinous Carcinoma of the Breast: MRI Features of Pure and Mixed Forms with Histopathologic Correlation

OBJECTIVE The purpose of this study was to describe the MRI features of the pure and mixed forms of mucinous carcinoma of the breast and the histopathologic correlation. MATERIALS AND METHODS Seventeen pure and three mixed mucinous tumors of the breast were examined with T2-weighted MRI and triple-phase dynamic MRI. MR images were reviewed for evaluation of the signal intensity and enhancement patterns of tumors and for correlation with the histopathologic findings. RESULTS The presence of very high signal intensity on T2-weighted images was a common feature of pure and mixed mucinous tumors. Fourteen pure tumors and one mixed tumor had very high signal intensity, and three pure and two mixed tumors had very high signal intensity and isointensity on T2-weighted images. The enhancement pattern during the early phase varied with the cellularity of pure tumors and with the distribution of nonmucinous components in mixed tumors. Hypocellular pure mucinous tumors had a typical pattern of gradual enhancement. CONCLUSION Hypercellular pure mucinous tumors exhibit strong early enhancement and may be difficult to differentiate from mixed mucinous tumors. The distinction between the pure and mixed forms of mucinous carcinoma is important because mixed mucinous carcinoma more frequently undergoes lymph node metastasis and has a poorer prognosis than does pure mucinous carcinoma.

Schistosomiasis of the liver

Schistosomiasis is an infection of trematodes, Schistosoma, causing periportal fibrosis and liver cirrhosis due to deposition of eggs in the small portal venules. In schistosomiasis caused by S. mansoni, sonography shows echogenic thickening or fibrotic band along the portal veins. CT shows low-attenuation bands or rings around the large portal vein branches in the central part of the liver with marked enhancement. Hepatoplenomegaly, liver cirrhosis, portal hypertension and gastroesophageal varies are commonly associated. In schistosomiasis caused by S. japonicum, sonography shows echogenic septae in the liver, utlining the polygonal liver lobules, mimicking “fish-scale” network appearance, reflecting fibrosis. CT shows periportal septae in the peripheral part of the liver parenchyma, producing “turtle-back” appearance, representing calcified eggs along the portal tracts. The portal tracts and hepatic capsule are enhanced on contrast-enhanced CT images. The size and shape of the liver are relatively preserved. MR images show fibrous septae as low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and these fibrous septae are enhanced. CT images of the lungs show multiple scattered nodules with halo of ground-glass opacities. Exudative granulomatous inflammation of the colonic wall may produce inflammatory polyps, fibrous thickening or stenosis of the colonic wall.

A case with primary amyloidosis of the liver and spleen: radiologic findings.

A case with primary amyloidosis of the liver and spleen is presented. In the liver, ultrasonography showed heterogeneous echogenicity. Portal phase CT showed heterogeneous enhancement, and delayed phase CT showed delayed enhancement with focal hypoattenuating areas. Bone scintigraphy showed diffuse accumulation. In the spleen, arterial phase CT showed the lack of parenchymal enhancement, and T2-weighted MR imaging showed decreased signal intensity. The combination of imaging findings of the liver and spleen was suggestive of amyloidosis.

Well-differentiated hepatocellular carcinoma: findings of US, CT, and MR imaging

AbstractBackground: To elucidate the imaging characteristics of well-differentiated hepatocellular carcinomas (HCCs) on ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging. Methods: Ultrasonograms, CTs, and MR images of 18 histopathologically proven well-differentiated HCCs in 15 patients were reviewed. The findings of these images were correlated with histopathologic findings. Results: On US, seven tumors were depicted as a hyperechoic area and eight as a hypoechoic area. Three tumors were not visualized. On precontrast CT, four tumors were depicted as a low-density area, but 14 were not visualized. On conventional contrast-enhanced CT, 12 tumors were depicted as a low-density area but six were not visualized. On T1-weighted MR images, 10 tumors had high signal intensity and two had low signal intensity. Six tumors were not visualized. On T2-weighted MR images, five tumors had high signal intensity and two had low signal intensity. Eleven tumors were not visualized. Tumors with fatty change and/or clear cell formation were frequently hyperechoic on US and hyperintense on T1-weighted MR images. Conclusions: Well-differentiated HCCs show different findings on US, CT, and MR imaging. Therefore, reliable diagnosis of well-differentiated HCCs by these imaging techniques may be difficult.

MR imaging of malignant mesenchymal tumors of the liver

Magnetic resonance (MR) features of five primary malignant mesenchymal neoplasms (plasmocytoma, leiomyosarcoma, undifferentiated sarcoma, epithelioid hemangioendothelioma, and angiosarcoma) of the liver were reported. All tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. No halo and intravenous extension were noted. A target appearance was revealed in epithelioid hemangioendothelioma. MR findings of angiosarcoma were essentially the same as those of cavernous hemangiomas (markedly hyperintense with hypointense linear septa on T2-weighted images). MR findings of these rare hepatic malignancies were nonspecific, although they were quite different from those of typical hepatocellular carcinomas. This study suggested that MR differentiation of primary hepatic mesenchymal tumors from other common benign and malignant neoplasms was difficult; however, the number of studied cases was limited.

Diagnostic performance of fluorodeoxyglucose-positron emission tomography/computed tomography of breast cancer in detecting axillary lymph node metastasis: comparison with ultrasonography and contrast-enhanced CT

PurposeThe purpose of this retrospective study was to evaluate the diagnostic performance of positron emission tomography/computed tomography (PET/CT) with fluorine-18–labeled 2-fluoro-2-deoxy-d-glucose (FDG) in comparison with that of ultrasonography and contrast-enhanced computed tomography (CT) in detecting axillary lymph node metastasis in patients with breast cancer.Materials and methodsFifty patients with invasive breast cancer were recruited. They had received no neoadjuvant chemotherapy and underwent PET/CT, ultrasonography and contrast-enhanced CT before mastectomy. The clinical stage was I in 34 patients, II in 15 patients, and III in one patient. The images of these modalities were interpreted in usual practice before surgery and the diagnostic reports were reviewed for analysis. Sensitivity, specificity, positive predictive value, and negative predictive value of each modality were obtained taking histopathological results of axillary lymph node dissection or sentinel lymph node biopsy as the reference standard.ResultsAxillary lymph node metastasis was confirmed in 15 of 50 patients by histopathological studies. PET/CT identified lymph node metastasis in three of these 15 patients. The overall sensitivity and specificity, positive predictive value, and negative predictive value of PET/CT in the diagnosis of axillary lymph node metastasis were 20, 97, 75, and 74%, and those of ultrasonography were 33, 94, 71, and 77% and those of contrast-enhanced CT were 27, 97, 80, and 76%, respectively.ConclusionsPET/CT showed poor sensitivity and high specificity in the detection of axillary lymph node metastasis of breast cancer. Diagnostic performance of PET/CT was not superior to that of ultrasonography and contrast-enhanced CT.

Acute Tumor Lysis Syndrome Caused by Transcatheter Oily Chemoembolization in a Patient with a Large Hepatocellular Carcinoma

Acute tumor lysis syndrome results from a sudden and rapid release of products of cellular breakdown after anticancer therapy. Severe alterations of metabolic profile might occur and result in acute renal failure. We present a patient with a large hepatocellular carcinoma who received transcatheter oily chemoembolization and died subsequently of this syndrome. To our knowledge, there has been only one report of this syndrome induced by chemoembolization for hepatocellular carcinoma. This case illustrates the need to anticipate the development of acute tumor lysis syndrome when chemoembolization is planned for a large hepatocellular carcinoma.

Incidental detection of clinically unexpected breast lesions by computed tomography

Background Increased use of computed tomography (CT) has resulted in greater detection of incidental breast lesions unrelated to the primary diagnostic inquiry. Purpose To investigate the morphology and clinical significance of breast abnormalities detected incidentally by conventional CT. Material and Methods A total of 2945 female patients underwent CT examinations of the body, including the chest, from May 2006 to April 2010. Two radiologists interpreted these CT scans independently and pointed out a mass or non-mass-like lesion as abnormalities in the breast. Patients who incidentally showed breast lesions on CT scans were identified by a computer-based search of the diagnostic reports and were enrolled in this study. The morphology and enhancement patterns of CT-detected breast lesions were evaluated according to BI-RADS-MRI. Results In total, 32 clinically unexpected abnormal breast lesions were found in 31 (1.1%) patients. Twenty-nine of the 32 lesions were detected by contrast-enhanced CT and three by unenhanced CT. Ten breast cancers were found in 10 patients (0.34%), which yielded the prevalence for malignancy of 31% (10/32). Invasive ductal carcinomas accounted for eight lesions, while two were ductal carcinomas in situ (DCIS). Nine lesions were depicted as a mass and one DCIS was a non-mass-like lesion. Good morphological predictors of breast cancers for a mass were an irregular shape, a lobulated shape, and an irregular margin. Benign lesions accounted for 22 lesions from 21 patients (0.71%). Of these, 13 lesions in 13 patients were depicted as a mass and nine lesions in nine patients as a non-mass-like lesion. Conclusion Unexpected breast lesions can be identified as a mass or non-mass-like lesion on conventional chest CT scans. Among these, breast cancers that are not clinically apparent occur with considerable prevalence. We suggest that careful interpretation of the breast should be a routine part of CT examinations.

Magnetic Resonance Imaging of Macroscopic Intrahepatic Portal-Hepatic Venous Shunts

Direct communication between portal branches and the hepatic vein [macroscopic intrahepatic portal-hepatic venous shunt (IPHVS)] is a rare entity. We have recently studied five patients with this condition. Magnetic resonance imaging (MRI) clearly demonstrated in each case the portal-hepatic venous shunt due to “flow void. “ Multiple diffuse shunts were present in one case and a solitary shunt was demonstrated in the others. The solitary shunt was either tubular, focally dilated or racemose in configuration. The MRI findings and clinical significance of this rare entity are discussed.