Ayame Shimizu

Diagnosis of gastric cancer with MDCT using the water-filling method and multiplanar reconstruction : CT-histologic correlation

OBJECTIVE The purpose of this study was to assess the utility of MDCT with a thin-sliced multiplanar reconstruction (MPR) technique and water-filling method for the diagnosis of gastric cancers. MATERIALS AND METHODS Sixty-five patients with gastric cancers were preoperatively examined with MDCT using the water-filling method. The abdomen was dynamically scanned at 30 and 80 sec after the start of contrast medium administration. MPR images were reconstructed with a slice width of 1.25 mm and a slice interval of 1 mm. The detection rate and accuracy of T staging for gastric cancer were evaluated on MPR images and compared with 5-mm-slice axial images. In addition, MDCT images were correlated with pathologic findings. RESULTS The detection rate of all gastric cancers using the MPR technique was 65%. The detection rate of advanced gastric cancers was 96.2% (25 of 26), whereas that of early gastric cancers was 41.2% (14 of 34). There was a statistically significant difference (p < 0.05) in the detection rate of early gastric cancers between MPR and 5-mm-slice axial images. The MDCT appearances of gastric cancers were well correlated with pathologic findings such as mucinous component or differences in infiltration of cancer cells. The overall accuracy of CT staging was 85%. MPR images were superior to axial images for the evaluation of the z-axis extent of tumor. CONCLUSION MDCT with the water-filling method has advantages in acceptable evaluation of depth invasion of gastric carcinomas and in visualization of histologic changes in the tumors. MPR images may be a useful guide for the evaluation of the z-axis extent of tumor.

Pre‐ and postprandial alterations of portal venous flow: Evaluation with single breath‐hold three‐dimensional half‐fourier fast spin‐echo MR imaging and a selective inversion recovery tagging pulse

To evaluate the influence of food intake on portal flow using unenhanced magnetic resonance imaging (MRI).

Imaging findings of unusual intra- and extrahepatic portosystemic collaterals.

We describe unusual portosystemic shunts demonstrated using computed tomography (CT) and magnetic resonance imaging (MRI), including gallbladder varices, aberrant left gastric vein to left portal vein collaterals, intrahepatic and transhepatic portosystemic venous shunt, and mesenteric varices. Familiarity with the CT and MRI features of unusual portosystemic shunts will help in making the correct diagnosis for affected patients.

Portal Venous System: Evaluation with Unenhanced MR Angiography with a Single-Breath-Hold ECG-Synchronized 3D Half-Fourier Fast Spin-Echo Sequence

OBJECTIVE Eighteen healthy persons underwent unenhanced MR angiography with a breath-hold ECG-synchronized 3D half-Fourier fast spin-echo technique to evaluate the visibility of the portal vein and its branches. CONCLUSION Our results indicated that unenhanced MR angiography with a singlebreath-hold ECG-synchronized 3D half-Fourier fast spin-echo sequence facilitates precise visualization of the anatomic features of the portal vein and its branches without the use of contrast agents.

Small hepatic lesions found on single-phase helical CT in patients with malignancy: Diagnostic capability of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) MR imaging using a half-fourier acquisition single-shot turbo spin-echo (HASTE) sequence

To evaluate the diagnostic capability of breath‐hold, multisection fluid‐attenuated inversion‐recovery (FLAIR) imaging using a half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) sequence in combination with T2‐weighted fast spin‐echo (FSE) magnetic resonance (MR) sequences for small hepatic lesions found on CT in patients with malignancy.

Cisterna chyli in patients with portal hypertension: Evaluation with MR imaging

To evaluate the difference in the caliber of cisterna chyli between patients with and without portal hypertension on magnetic resonance imaging (MRI) and to assess the alteration of the caliber of cisterna chyli related to contraction waves during serial T2‐weighted MRI.

Evaluation of intraportal venous flow distribution by unenhanced MR angiography using three-dimensional fast spin-echo with a selective tagging pulse: Efficacy of subtraction of tag-on and tag-off images acquired during a single breath-hold

To evaluate the efficacy of subtracted MR images from two sets of unenhanced three‐dimensional (3D) MR angiography data (tag‐on and tag‐off images) acquired simultaneously during a single breath‐hold in assessing the intraportal venous flow distribution to the distal branches from the superior mesenteric vein (SMV) and the splenic vein (SpV).

Hepatocellular lesions with increased iron uptake on superparamagnetic iron oxide-enhanced magnetic resonance imaging in cirrhosis or chronic hepatitis: comparison of four magnetic resonance sequences for lesion conspicuity

PURPOSE The aim of this study was to determine the adequate MR sequence for the lesion conspicuity of hepatocellular lesions with increased iron uptake on superparamagnetic iron oxide (SPIO)-enhanced MRI. MATERIALS AND METHODS SPIO-enhanced MRI was performed using a 1.5-T system. Among 25 patients with hypovascular hepatocellular nodules on contrast-enhanced dynamic CT (no early enhancement at arterial phase and hypoattenuation at equilibrium phase), 39 lesions with increased iron uptake on SPIO-enhanced MRI were evaluated. SPIO-enhanced MRI included (1) T1-weighted in-phase gradient recalled echo (GRE) images, (2) T2-weighted fast spin echo (FSE) images, (3) T2*-weighted GRE with moderate TE (7 ms) and (4) long TE (12 ms). The lesion-to-liver contrast-to-noise ratios of the hepatocellular nodule and the signal-to-noise ratio (SNR) of the hepatic parenchyma were calculated by one radiologist for a quantitative assessment. MR images were reviewed retrospectively by two independent radiologists to compare the subjective lesion conspicuity in each image set based on a four-point rating scale. RESULT The mean lesion-to-liver contrast-to-noise ratios with T2*-weighted GRE with moderate TE (7 ms) was highest (5.79+/-3.71) and was significantly higher than those with T1-weighted, in-phase images (3.79+/-3.23, P<.01), T2-weighted images (2.72+/-1.52, P<.001) and T2*-weighted GRE with long TE (12 ms) (3.93+/-2.69, P<.05). The subjective rating of lesion conspicuity was best on the T2*-weighted GRE with moderate TE (7 ms), followed by that on the T2*-weighted GRE with moderate TE (7 ms; P<.05). CONCLUSION T2*-weighted GRE sequence with moderate TE (7 ms) showed high lesion-to-liver contrast-to-noise ratios in hepatocellular lesions with increased iron uptake on SPIO-enhanced MRI, indicating better lesion conspicuity of hypointense hepatocellular nodules in cirrhosis or chronic hepatitis.

Nondiffuse fatty infiltration of the liver: Does the uptake of iron-oxide increase or decrease at SPIO-enhanced MR imaging?

PURPOSE To clarify whether the uptake of SPIO increases or decreases in areas of fatty change compared with surrounding areas of nonfatty change at SPIO-enhanced MR imaging. MATERIALS AND METHODS Approval for this retrospective study was obtained from our institutional review board. This study included 14 patients with nondiffuse fatty infiltration of the liver who underwent SPIO-enhanced MR imaging. Additionally, 30 patients without nondiffuse fatty infiltration of the liver were also evaluated. RESULTS Among 14 patients, areas of fatty change showed relatively high signal intensity in 7 patents, indicating decreased uptake of SPIO in areas of fatty change. In these 7 patients, 4 had mild cirrhosis and 3 did not have cirrhosis. The mean percentage of signal intensity loss (42%) of fatty areas was significantly lower (p<0.007) than that of adjacent areas of nonfatty change (52%). In the remaining 7 of 14 patients, areas of fatty change showed relatively low signal intensity, indicating increased uptake of SPIO in areas of fatty change. Among these 7 patients, 6 had advanced cirrhosis. The mean percentage of signal intensity loss (47%) of fatty areas was significantly higher (p<0.008) than that of adjacent areas of nonfatty change (31%). CONCLUSION The uptake of SPIO generally decreased in areas of fatty change compared with normal liver parenchyma at SPIO-enhanced MR imaging. However, in patients with advanced cirrhosis, areas of fatty change shows relatively low signal intensity because the uptake of SPIO in surrounding areas of nonfatty change severely decreased probably due to liver fibrosis.