Published papers

PURPOSE: To evaluate whether the vascular pattern at power Doppler ultrasonography (US) improves diagnostic accuracy in small solid renal lesions over that at gray-scale US. MATERIALS AND METHODS: Gray-scale and power Doppler US were performed prospectively in 64 small (1.5-3.0-cm- diameter) solid renal lesions (26 renal cell carcinomas [RCCs], 34 angiomyolipomas, two oncocytomas, two pseudotumors). At gray-scale US, echogenicity and homogeneity of the lesion, an anechoic rim, intratumoral cysts, shadowing, or a central scar were sought. At power Doppler US, the vascular distribution was divided into four patterns. RESULTS: Findings at gray-scale US included an anechoic rim or intratumoral cysts in 20 of 26 RCCs (77%) and the two oncocytomas. Shadowing was seen in seven of 34 angiomyolipomas (21%). Echogenicity, homogeneity, and a central scar were not pathognomonic. At power Doppler US, pattern 3 (peripheral) or 4 (mixed penetrating and peripheral) was seen in all RCCs, seven of 34 angiomyolipomas, and the two oncocytomas. Pattern 1 (intratumoral focal) or 2 (penetrating) was seen in 27 angiomyolipomas. Pattern 1 or 2 was characteristic of angiomyolipomas. The rate of correct diagnosis was significantly increased with combined US (78%) as compared to that with gray- scale (42%) or power Doppler (45%) US alone. CONCLUSION: The vascular distribution at power Doppler US could add important information to gray- scale US findings for differential diagnosis of small solid renal lesions.

The MRI features of small renal cell carcinomas (RCCs) were retrospectively reviewed and correlated with histology in 24 patients. MRI features on both T1- and T2-weighted images were classified into hypointensity, isointensity, and hyperintensity. Each tumor was pathologically classified into four types: alveolar, papillary, tubular, and cystic. These findings were correlated with MR signal intensities. Alveolar tumors showed hypointensity to isointensity on T1-weighted image and isointensity to hyperintensity on T2-weighted image. In contrast, all papillary tumors showed hypointensity on T2-weighted image. Four of six tumors with hypointensity on T2-weighted image were caused by hemosiderin deposition, hemorrhage, and necrosis. However, there were two papillary RCCs that showed hypointensity on T2-weighted image despite no hemosiderin deposition and no hemorrhage. We conclude that papillary RCC is associated with T2-hypointense appearance as well as hemosiderin deposition, hemorrhage, and necrosis.

The performance of gadolinium-ethoxybenzyl- diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) and superparamagnetic iron oxide (SPIO) particles in detecting liver cancer was compared using alternative free-response receiver operating characteristic (AFROC) analysis, which allowed observers to indicate both the confidence level and the location of all perceived abnormalities. Axial T1-weighted MR images (1.5 T) pre/post Gd-EOB-DTPA (25 μmol/kg) injection were obtained for 12 rats with chemically induced liver tumors (64 tumors). T2-weighted images (T2WI) were obtained pre/post SPIO (10 μmol/kg) injection for the same animal. Liver signal-to-noise ratio (SNR), tumor liver contrast-to-noise ratio (CNR), and histopathologic sections corresponding to MR images were obtained. In AFROC, the location and the confidence level for each tumor were indicated independently on MR images by four radiologists. By plotting true-positive fraction and probability of false-positive per image, the area under the AFROC curve (A1) was estimated and statistically analyzed between each sequence. Either drug significantly improved tumor-liver CNR (P < .001) and tumor detection (diameter ≤ 6 mm; P < .05). Gd-EOB-DTPA significantly (P < .05) improved the A1 in T1W1. There was no A1 difference between T2WI + SPIO and T1WI + Gd-EOB-DTPA. Gd-EOB-DTPA-enhanced T1WI showed the same performance as SPIO-enhanced T2WI in detecting liver tumors.

Purpose: Our goal was to characterize the radiologic features of liver metastases from colon cancer with intrahepatic bile duct (IHBD) dilatation. Method: Radiologic findings of liver metastases from colon cancer with IHBD dilatation of four patients were compared with pathologic findings. Results: The cause of bile duct dilatation in all cases was due to papillary tumor growth in the bile duct. In two patients, intra-bile duct tumor growth (IBDTG) was observed on imaging. In the other two patients, IBDTG was not observed, but a nontapered abrupt obstruction of a dilated bile duct was seen, corresponding to the microscopically proven papillary tumor growth in the ductal lumen. In three patients who underwent an extensive hepatic resection, there has been no recurrence. In one patient who had a nonanatomic limited resection, a recurrence was seen 1 year after surgery. Conclusion: When liver tumor with IBDTG is suspected on imaging, liver metastases should be considered in the differential diagnosis besides hepatocellular carcinoma or cholangiocellular carcinoma. Careful preoperative assessment for IBDTG by imaging is essential to determine the extent of surgical resection.

We investigated the frequency and causative factors of symptoms unrelated to contrast media (false late adverse reactions) among patients who were evaluated as having late adverse reactions to contrast media. The nature and frequency of complaints stated by each 200 of patients who underwent plain CT scans and enhanced CT scans were evaluated. In the plain CT group, three patients showed false late adverse reactions. The frequency was 2.6% among respondents and 1.5% in the population. These symptoms encompassed psychological effects and diseases that developed after CT scanning. It is difficult to detect only true late adverse reactions, because of survey bias.

Intravascular ultrasound (IVUS) is a new method in which endovascular images are obtained from a catheter inserted into an artery. We uses IVUS during PTA of iliac and renal artery, and examined its effectiveness. Three layers are well defined in normal arterial wall. Calcified deposits are recognized as a combination of strong echo and acoustic shadow. The absolute cross sectional area of patent lumen and atherosclerotic plaque can be calculated. IVUS is very effective for the assessment of PTA. The increased caliber of arteries following PTA is caused by the over stretching of the media rather than the compression of atheroma.

We evaluated 12 cases of small renal cell carcinoma without necrosis or hemorrhage, especially concerning their echogenicity in relation to cell types, grading of cellular atypia, amount of stroma, and architectural arrangement. Among the twelve cases, 4 cases were hyperechoic and 8 cases were isoechoic. No hypoechoic lesion was found in this series. There were no meaningful differences in cell types or in the grading of cellular atypia between the hyperechoic type and the isoechoic type. In regard to the amount of stroma, all cases were of the medullary type, so this factor did not contribute to the difference of echogenicity in this series. Concerning the architectural arrangement the isoechoic types consisted of only the alveolar type, while the hyperechoic types were of the tubular type, the papillary type or the alveolar type coexisting with the diffusely scattered cytic type. It is suggested that the alveolar types would be isoechoic, while the tubular, papillary or cystic types would be hyperechoic. These results suggest that cellular factors such as cell types or the grading of cellular atypia may not affect the echogenicity of renal cell carcinoma, but that structural factors such as the architectural arrangement may affect it. Cavitary components of approximately 30-60 μ in diameter were found to be common in the structure of the hyperechoic types. We propose that a standard classification of echogenicity should be determined to facilitate discussion of the relation between echogenicity and pathohistological findings.