Kyo Tsuda

Optimal phases of dynamic CT for detecting hepatocellular carcinoma: evaluation of unenhanced and triple-phase images

AbstractBackground: To determine the optimal phases of dynamic computed tomography (CT) for detecting hepatocellular carcinoma (HCC). Methods: Fifty-two patients with 85 HCC nodules were examined by means of unenhanced and triple-phase CT images of the whole liver. The time for obtaining the arterial-phase images was 25–55 s after intravenous bolus injection of contrast material, the time for obtaining the portal venous-phase images was 65–100 s, and the time for obtaining late-phase images was 145 s to 4 min. Detectability of the HCC nodules for all phases was statistically compared. Results: The detection rates for the arterial- and late-phase images were significantly higher than for the unenhanced and portal venous-phase images (p < 0.01). The combination of arterial- and late-phase images showed the same number of HCC nodules in the same number of patients as did the combination of unenhanced and triple-phase images. Conclusion: The combination of the arterial- and late-phase imagings was best for detecting HCC nodules.

CT and MRI of Siderotic Regenerating Nodules in Hepatic Cirrhosis

The demonstration by CT of siderotic regenerating liver nodules in cirrhosis was evaluated and compared with that of MR imaging retrospectively in 27 patients with histologically diagnosed hepatic cirrhosis. Only in one of the two patients with marked iron deposits in regenerating nodules did CT demonstrate multiple high density nodules. In the other patient with marked iron deposits and in seven of the nine patients with moderate iron deposits, the liver parenchyma on CT was demonstrated as heterogeneous and of slightly high density without focal nodules. In 8 patients with mild to moderate iron deposits and in the 10 with no iron deposits, the liver parenchyma was homogeneous on CT. Multiple low intensity nodules in the liver were seen on fast low-angle shot (FLASH) MR images in all 17 patients with iron deposits in regenerating nodules. No low intensity nodules were seen on FLASH MR images in the 10 patients with no iron deposits. If there are iron deposits above a certain level, siderotic regenerating nodules may appear as nodules of high density on CT or as heterogeneous regions of high density liver parenchyma. Magnetic resonance is more sensitive than CT in demonstrating siderotic regenerating nodules.

Intramural invasion of gastric cancer: evaluation by CT with water-filling method.

Objective Our goal was to clarify the ability of CT to evaluate intramural invasion of gastric cancer. Materials and Methods We reviewed bolus-enhanced CT images performed with orally administered 400–600 ml of water in 59 early gastric cancers and 22 advanced gastric cancers mimicking early gastric cancers macroscopically. Results CT was able to reveal 49% of early gastric cancers and 68% of advanced gastric cancers mimicking early cancers. Twenty-seven gastric tumors were detected in two or three layered structure of wall. Morphologic features of early gastric cancers are strong enhancement without wall thickening and thickened inner layer with normal middle and outer layers. Morphologic features of early advanced gastric cancers are a thickened wall with disappeared middle and outer layers and transmural enhancement with wall thickening. If one of these features was used to predict whether the tumor was early or early advanced gastric cancer in detected cases, specificity was 93–100%, sensitivity was 7–72%, and positive predictive value was 80–100%. Conclusion We evaluated whether the wall pattern of gastric tumors on CT can provide useful information about intramural invasion.

Detection of viable tumor cells in hepatocellular carcinoma following transcatheter arterial chemoembolization with iodized oil. Pathologic correlation with dynamic turbo-FLASH MR imaging with Gd-DTPA.

To evaluate the effect of transcatheter arterial chemoembolization (TACE) with iodized oil for hepatocellular carcinoma (HCC), dynamic turbo-fast low angle shot (turbo-FLASH) (TR/TE/flip angle/TI, 8.5/4.6/10/200) MR imaging with gadopentetate dimeglumine was performed in 10 patients with HCC after TACE with iodized oil and before partial hepatectomy. Immediately after 0.05 mmol/kg b.w. of gadopentetate dimeglumine was administered intravenously, 10 images were obtained in the first 20 s (early phase). Then, one image every 30 s from 1 to 3 min (late phase), and images at 5 min and 7 min (delayed phase) were obtained serially. In the early phase, HCC showed no enhancement in 5 patients, partial hyperintense enhancement in 4, and total hyperintense enhancement in one. Viable regions of the tumor, evaluated at histopathology, showed hyperintense enhancement relative to the surrounding liver parenchyma in the early phase, while necrotic regions showed no enhancement. Both viable and necrotic regions showed lower signal intensities than the surrounding liver parenchyma in both late and delayed phases. By using dynamic turbo-FLASH MR imaging, we were able to accurately evaluate the effect of TACE with iodized oil for HCC in 8 of the 10 patients. In 2 patients, in whom small viable cells were seen in the HCC, viable regions could not be detected with our technique. It is concluded that turbo-FLASH dynamic MR imaging was useful for evaluating the effect of TACE for HCC.

MR Evaluation of Mediopatellar Plica

Purpose: Evaluation of the usefulness of MR imaging for diagnosing mediopatellar plica (MP) of the knee joint. Material and Methods: We prospectively examined MR images of 40 knee joints in 30 patients with symptoms. The pulse sequences were SE T1-weighted images (600/26 ms), T2-weighted images (1800/70), and FLASH images (320/15/flip angle 90°). When a low-intensity band was found above the medial condyle of the femur on T1-weighted and T2-weighted MR images, we defined it as MP. We compared these MR findings with arthroscopic findings, including the Sakakibara classification of MP. Results: In 29 of the 40 knee joints in which MP was arthroscopically found, 27 were correctly diagnosed as having MP on MR. In the remaining 11 without MP, 9 were correctly diagnosed by MR. Conclusion: MR images are useful not only for detecting MP but also for evaluating its extension. Our results suggest that MR imaging is useful as a screening method for detecting MP before arthroscopy.

Helical CT angiography of living renal donors : Comparison with 3D Fourier transformation phase contrast MRA

PURPOSE The purpose of this study was to determine whether helical CT angiography (CTA) or MR angiography (MRA) is the optimal method to use as a preoperative examination for anatomic arterial assessment of living renal donors. METHOD Eighteen candidates to be renal donors underwent helical CTA, 3D Fourier transformation phase contrast (3D-FT-PC) MRA, and digital subtraction angiography (DSA). The CTA and MRA were interpreted separately by three readers independently, and these results were correlated with the findings of DSA. RESULTS DSA showed nine accessory renal arteries and 10 prehilar branches. CTA revealed seven or eight accessory renal arteries. MRA showed six or seven accessory arteries. Of 10 prehilar branches, 7-9 branches were detected with CTA and 5-8 branches with MRA. CONCLUSION Helical CTA is superior to 3D-FT-PC MRA for evaluating the arterial anatomy of living renal donors.

Detection of hypervascular hepatocellular carcinoma: comparison of SPIO-enhanced MRI with dynamic helical CT.

Purpose The purpose of this study was to compare the diagnostic performance of superparamagnetic iron oxide (SPIO)-enhanced MRI for the detection of hypervascular hepatocellular carcinoma (HCC) with dynamic helical CT. Methods SPIO-enhanced MR and dynamic helical CT images obtained from 41 patients with 52 hypervascular HCCs (5–130 mm; mean, 27 mm) were retrospectively analyzed. MRI were obtained with 1.5 T scanners using T2-weighted and proton density-weighted spin-echo (or fast spin-echo) sequences for all cases and a T2*-weighted gradient echo sequence for 36 cases. Four blinded observers reviewed images independently. Diagnostic accuracy was evaluated using alternative-free response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values (PPV) were also evaluated. Results The areas under the AFROC curves for each observer were greater for MR than for CT (means, 0.81 and 0.76; p < 0.05). The mean sensitivities for MR and CT were 0.75 and 0.71, respectively (p = 0.13). The mean PPVs were 0.83 and 0.79 (p = 0.21). Conclusion SPIO-enhanced MRI showed slightly better diagnostic performance than dynamic helical CT for the detection of hypervascular HCCs.

MR imaging of cervical carcinoma: comparison among T2-weighted, dynamic, and postcontrast T1-weighted images with histopathological correlation

Abstract.Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images.

CILIATED FOREGUT CYST IN CIRRHOTIC LIVER

We encountered a patient with a ciliated hepatic foregut cyst with accompanying liver cirrhosis, which was hard to distinguish from well-differentiated hepatocellular carcinoma. A lesion 2 cm in diameter was found in the subcapsular region of the medial segment of the liver. It was slightly hypoechoic on ultrasononraphy, of high attenuation on nonenhanced computed tomography (CT), of high intensity on T1-weighted spin echo images of magnetic resonance imaging (MRI), and of isointensity on T2-weighted spin echo images. It was not enhanced in the arterial phase images of MRI, and was shown as a complete perfusion defect on CT arterial portography. The cyst was enucleated and found to be filled with bloody mucinous fluid.

Cervical Invasion of Endometrial Carcinoma — Evaluation by Parasagittal MR Imaging:

Twenty-seven consecutive patients were examined by T2-(1 800/70 ms) and postcontrast T1-weighted (600/15) spin echo (SE) or dynamic (200/15) SE MR imaging to determine the usefulness of parasagittal MR imaging in assessing cervical invasion of endometrial carcinoma. The images were obtained in a direction parallel to the longitudinal axis of the uterus (parasagittal). The cervical epithelium, being hyperintense on the late phase dynamic and postcontrast T1-weighted SE images, had disappeared partially or totally in all 4 patients with cervical invasion. The enhanced cervical epithelium was completely seen in one patient with the tumor protruding into the cervical canal in a polyp-like form without cervical epithelial invasion. The same was also seen in the 22 patients with the tumor remaining in the corpus cavity. The enhanced parasagittal MR images facilitated the evaluation of the extent of the endometrial carcinoma.