Masayuki Kamba

Transneuronal degeneration in patients with temporal lobe epilepsy: evaluation by MR imaging

The aim of this study was to assess the MR imaging findings of transneuronal degeneration of limbic system in the patients with temporal lobe epilepsy, and to detect the influence of surgery on the anatomy of the limbic system. Axial and coronal T1- and T2-weighted MR images were retrospectively analyzed in 34 patients with temporal lobe epilepsy, focusing on transneuronal degeneration. In 17 of the 34 patients, MR images were also analyzed after selective amygdalo-hippocampectomy. Atrophy of the fornix, mamillary body, mamillothalamic tract (MTT), and thalamus ipsilateral to the epileptic focus was demonstrated on MR images in 14.7, 17.6, 8.8, and 11.8% of the 34 patients, respectively. Focal hyperintensity of the thalamus was found on T2-weighted images in 8.8% of the 34 patients. In 17 patients who were evaluated before and after surgery, transneuronal degeneration was seen more frequently after surgery: fornix (11.8 vs 29.4%), mamillary body (11.8 vs 52.9%), MTT (5.9 vs 11.8%), and thalamus (11.8 vs 11.8%). Transneuronal degeneration of the limbic system is clearly demonstrated by MR imaging in patients with temporal lobe epilepsy, and surgical intervention induces transneuronal degeneration more frequently.

Chondroitin Sulfate Iron Colloid as MR Contrast Agent in Differentiation between Hepatocellular Carcinoma and Adenomatous Hyperplasia

Using a 1.5 T MR imaging unit, T1- and T2-weighted images were obtained before and after i.v. administration of chondroitin sulfate iron colloid (CSIC) in order to differentiate hepatocellular carcinoma (n = 20) from adenomatous hyperplasia without atypia (n = 16). Differentiation was made from the tumor-liver contrast to noise ratio (CNR) and visual evaluation of the nodule, with reference to signal intensity relative to that of the surrounding liver. The CNR of adenomatous hyperplasia was on T1-weighted images significantly decreased after CSIC administration (p < 0.01). On T2-weighted images, there was no significant difference in CNR after CSIC administration. On the other hand, the CNR of hepatocellular carcinoma was significantly increased after CSIC administration on both T1- and T2-weighted images (p < 0.01). CSIC reflects intratumor reticuloendothelial cellular functions, and is therefore useful in differentiating hepatocellular carcinoma from adenomatous hyperplasia without atypia.

Progression of neuronal processing of visual objects

We studied, with functional MRI, how neuronal processing for visual objects progresses in the human brain by measuring suppressive responses to stimulus pairs. Two concentric rectangular frames of slightly different sizes were presented such that the smaller frame was shown first, followed by the larger dominant frame, with interstimulus intervals of 0, 50 and 240-ms. The functional MRI response at 50-ms decreased along the ventral visual pathway. The response at 240-ms interstimulus interval was suppressed after a fusiform area at which the response at 50-ms interstimulus interval was highly suppressed already and the responses at 0, 50 and 240-ms interstimulus intervals showed a V-shaped dependence on those interstimulus intervals. These observations show a way of progression of the information processing along visual object recognition pathway.

Comparison of various techniques of iron oxide-enhanced breath-hold MR imaging of hepatocellular carcinoma

The purpose of our study is to compare qualitatively and quantitatively the abilities of various superparamagnetic iron oxide (SPIO)-enhanced breath-hold magnetic resonance imaging (MRI) techniques to detect hepatocellular carcinoma (HCC). Eight patients with HCCs were imaged. The images were obtained with conventional T2-weighted spin-echo imaging (CSE), half-Fourier single-shot turbo spin-echo (HASTE), single-shot gradient-echo type echo planar imaging (GE-EPI), and single-shot spin-echo type echo planar imaging (SE-EPI) before and after SPIO administration. The liver signal-to-noise ratios (SNRs) in CSE and each EPI sequence were significantly decreased after SPIO administration. GE-EPI had the highest decrease ratio (DR) of liver SNR, followed by SE-EPI (TE=98), SE-EPI (TE=28), CSE, and HASTE in this order. The relative contrasts with GE-EPI and SE-EPI (TE=98) were significantly higher than that with CSE after SPIO administration. On receiver operating characteristic (ROC) analysis, diagnostic accuracy did not differ significantly among the pulse sequences after SPIO administration. GE-EPI and SE-EPI (longer TE) were useful for SPIO-enhanced breath-hold MRI performed to detect HCC.

Asymptomatic membranous obstruction of the inferior vena cava forming intrahepatic collateral pathways

Intrahepatic and/or extrahepatic collateral pathways result from the membranous obstruction of the inferior vena cava. These collaterals are usually insufficient to prevent Budd-Chiari syndrome. We reprot an unusual case of asymptomatic membranous obstruction of the inferior vena cava in which marked intrahepatic collateral pathways were formed. Although the inferior vena cava terminated above the orifice of the right hepatic vein, the middle and left hepatic veins were patent above the membrane, without narrowing. Blood from the inferior vena cava drained into the right atrium via the intrahepatic collaterals between the right and middle hepatic veins without resistance.

Correlation between Chondroitin Sulfate Iron Colloid-Enhanced MR Imaging and the Histological Grade of Hepatocellular Carcinoma

The association between contrast enhancement by chondroitin sulfate iron colloid (CSIC) and the histological grade of hepatocellular carcinoma (HCC) was evaluated in 24 patients diagnosed by histological examination of surgical specimens (26 nodules: 11 well-differentiated and 15 poorly—moderately-differentiated nodules). In the well-differentiated HCC nodules, the tumor—liver contrast to noise ratio (CNR) was not significantly increased after i.v. CSIC injection on both T1-weighted and T2-weighted images. In the moderately-poorly-differentiated HCC, CNR was significantly increased after CSIC administration on both T1-weighted and T2-weighted images (p<0.01). MR imaging using CSIC may be useful for diagnosing the degree of HCC differentiation.

Three-dimensional black blood MR angiography of the liver during breath holding: A comparison with two-dimensional time-of-flight MR angiography

In 2-D time-of-flight MR angiography (2-D TOF MRA) of the liver, artifacts caused by respiratory motion are unavoidable. Therefore, a 3-D black blood MRA of the liver was attempted in 7 healthy volunteers, using a 3-D gradient echo sequence which allows imaging during breath holding. 2-D TOF MRA was performed as well. In all subjects, 3-D MRA allowed visualization of the trunk, 1st-, and 2nd-order branches of the portal vein without interruption. Right 3rd-order branches were visualized without interruption in 6 of 7 subjects (85%). However, with 2-D MRA, the transverse portion of the left main portal vein could not be visualized in any subject, and the periphery of the portal vein was less clear than with 3-D MRA.

Alteration of blood oxygenation level-dependent signaling by local circulatory condition

To determine regional differences in the relationship between neuronal activation and blood oxygenation level‐dependent (BOLD) signal changes.

Measurement of relative fat content by proton magnetic resonance spectroscopy using a clinical imager

The aim of this study was to determine the applicability of a proton magnetic resonance (MR) spectroscopy‐based technique using a clinical 1.5‐T MR imager for assessment of relative fat content. Proton MR spectra were obtained from a trunk phantom and 23 volunteers using a single free induction decay measurement. The ratios of fat methyl and methylene proton resonance to the water proton resonance were compared with the ratio of oil weight to water weight for the phantom, and with the ratio of body fat to lean body mass estimated by bioelectrical impedance analysis for the human subjects. Good linear relationships were found between the MR metabolite ratio and the ratio of oil weight to water weight (r = 0.9989), and the ratio of body fat to lean body mass (r = 0.9169). This MR spectroscopy‐based technique is sufficiently accurate and may be applicable to assessment of human body composition. J. Magn. Reson. Imaging 2000;11:330–335.

Chondroitin sulfate iron colloid-enhanced MR imaging in patients with hepatocellular carcinoma. Comparison with CT during arterial portography.

Chondroitin sulfate iron colloid (CSIC) was used as an MR contrast agent for the detection of hepatocellular carcinoma (HCC). The findings of 25 surgically confirmed HCCs in 19 patients were retrospectively analyzed. T1-, T2- and proton density-weighted spin echo MR images were obtained before and after i.v. injection of 23.6 microM Fe/kg of CSIC. Unenhanced and CSIC-enhanced MR images and images obtained by CT during arterial portography (CT-AP) were correlated with surgical pathology findings. The sensitivities of CSIC-enhanced and unenhanced MR imaging, and CT-AP were 92%, 80%, and 88%, respectively. No significant differences were noted. Portal flow abnormalities demonstrated by CT-AP did not affect the detection of HCC by CSIC-enhanced MR imaging. CSIC-enhancement at MR imaging was a disadvantage in the detection of lesions less than 1 cm in diameter. CSIC-enhanced MR imaging is a supplemental method for the detection of HCC.