Shigenori Matsushima

MR Imaging of Ventral Thalamic Nuclei

BACKGROUND AND PURPOSE: The Vim and VPL are important target regions of the thalamus for DBS. Our aim was to clarify the anatomic locations of the ventral thalamic nuclei, including the Vim and VPL, on MR imaging. MATERIALS AND METHODS: Ten healthy adult volunteers underwent MR imaging by using a 1.5T whole-body scanner. The subjects included 5 men and 5 women, ranging in age from 23 to 38 years, with a mean age of 28 years. The subjects were imaged with STIR sequences (TR/TE/TI = 3200 ms/15 ms/120 ms) and DTI with a single-shot echo-planar imaging technique (TR/TE = 6000 ms/88 ms, b-value = 2000 s/mm2). Tractography of the CTC and spinothalamic pathway was used to identify the thalamic nuclei. Tractography of the PT was used as a reference, and the results were superimposed on the STIR image, FA map, and color-coded vector map. RESULTS: The Vim, VPL, and PT were all in close contact at the level through the ventral thalamus. The Vim was bounded laterally by the PT and medially by the IML. The VPL was bounded anteriorly by the Vim, laterally by the internal capsule, and medially by the IML. The posterior boundary of the VPL was defined by a band of low FA that divided the VPL from the pulvinar. CONCLUSIONS: The ventral thalamic nuclei can be identified on MR imaging by using reference structures such as the PT and the IML.

Multitensor Tractography Enables Better Depiction of Motor Pathways: Initial Clinical Experience Using Diffusion-Weighted MR Imaging with Standard b-Value

BACKGROUND AND PURPOSE: The purpose of this work was to test the feasibility of using high angular resolution diffusion imaging (HARDI)-based multitensor tractography to depict motor pathways in patients with brain tumors. MATERIALS AND METHODS: Ten patients (6 males and 4 females) with a mean age of 52 years (range, 9–77 years) were scanned using a 1.5T clinical MR unit. Single-shot echo-planar imaging was used for diffusion-weighted imaging (repetition time, 6000 ms; excitation time, 88 ms) with a diffusion-sensitizing gradient in 32 orientations and a b-value of 1000 s/mm2. Data postprocessing was performed using both the conventional single- and multitensor methods. The depiction rate of the 5 major components of the motor pathways, that is, the lower extremity, trunk, hand, face, and tongue, was assessed. RESULTS: Motor fibers on both lesional and contralesional sides were successfully depicted by both the single-tensor and multitensor techniques. However, with the single-tensor model, the depiction of motor pathways was typically limited to the fibers of trunk areas. With the multitensor technique, at least 4 of 5 major fiber bundles arising from the primary motor cortex could be identified. CONCLUSION: HARDI-based multitensor tractography using a standard b-value (1000 s/mm2) can depict the fiber tracts from the face and tongue regions of the primary motor cortex.

The pyramidal tract has a predictable course through the centrum semiovale: A diffusion‐tensor based tractography study

To identify reproducible anatomical landmarks that would allow predicting the course of the pyramidal tract (PT) through centrum semiovale.

Diaphragmatic Hernia After Radiofrequency Ablation for Hepatocellular Carcinoma

We describe a 71-year-old woman with a hepatocellular carcinoma who underwent percutaneous radiofrequency ablation (RF) with a single internally cooled electrode under computed tomography (CT) fluoroscopic guidance. Nine months after the procedure, CT images showed herniation of the large intestine into the right pleural cavity. To our knowledge this complication of RF performed with a single internally cooled electrode under CT guidance has not been previously reported.

Simultaneous impairment of intracranial and peripheral artery vasoreactivity in CADASIL patients.

Background: Reduced cerebrovascular reactivity (CVR) is an important step in the pathogenesis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The present study utilized quantitative single photon emission computed tomography (SPECT) with the autoradiographic (ARG) method and reactive hyperemia peripheral arterial tonometry (RH-PAT) to assess vasoreactivity in intracranial arteries and in peripheral arteries in patients with CADASIL. Methods: Quantitative SPECT studies were conducted in eight patients with CADASIL, while RH-PAT analysis was conducted in eight CADASIL patients and in eight age-matched normal subjects. Quantitative SPECT studies with the ARG method were performed at baseline and after administration of acetazolamide. Regional cerebral blood flow (rCBF) values were measured using stereotactic extraction estimation (SEE) methods. The rCBF of CADASIL patients was averaged in the bilateral frontal, temporal, parietal, and occipital lobes as well as in the limbic system, cerebellar hemisphere, whole cerebral cortex and basal ganglia. The CVR index from acetazolamide stress of intracranial arteries was calculated in each area. Vasoreactivity of peripheral arteries was estimated by the reactive hyperemia index (RHI) measured with a PAT device before and after interruption of arterial flow. Results: Average RHI after post-deflation was lower in CADASIL patients than in normal subjects. RHI correlated significantly with CVR in all brain areas in CADASIL patients. Conclusions: Vasoreactivity is reduced in peripheral arteries and in intracranial arteries in patients with CADASIL.

Distribution of Amyloid Burden Differs between Idiopathic Normal Pressure Hydrocephalus and Alzheimer's Disease

This study aimed to elucidate the incidence and distribution of the cortical retention of Pittsburgh compound B (PIB) in patients with idiopathic normal pressure hydrocephalus (iNPH) and clarify the differences from those in patients with Alzheimers disease (AD). Ten patients with iNPH without any clinical signs indicative of AD were enrolled in this study. Cerebral retention of PIB in positron emission tomography (PET) in iNPH patients was compared with those in seven age-matched AD patients. The CSF levels of β-amyloid 1–42 peptide (Aβ42), which inversely decrease with cerebral amyloid burden, were also measured. Three of the ten patients with iNPH showed increased cortical PIB retention. Although the mean cortical SUV ratios were similar, the distribution of PIB retention differed widely between the patients with iNPH and AD. PIB retention was limited to the high-convexity parasagittal areas in iNPH patients, whereas it spread over the frontal and parietotemporal areas in AD. The coronal images of PIB-PET were more informative than conventional transverse images in evaluating the distribution pattern of cortical PIB retention. Two iNPH patients with higher cortical PIB retention had the lowest levels of CSF Aβ42, indicating that PIB retention in iNPH would not reflect a simple delay in PIB clearance but its binding to existing Aβ amyloid in the brain. Our results indicate that iNPH is one of the diseases exhibiting cortical PIB retention. The characteristic distribution of PIB retention in iNPH could be useful in the differential diagnosis between iNPH and AD.

Effect of vascular stenosis on perfusion-weighted imaging; differences between calculation algorithms

To determine the most suitable postprocessing technique for magnetic resonance (MR) perfusion imaging in patients with vascular stenosis, by comparing the cerebral blood flow (CBF) maps of single photon emission tomography (SPECT) and perfusion MR imaging (MRI).

Intense F-18 FDG accumulation in idiopathic tumoral calcinosis.

An elderly Japanese woman presented to our hospital with a 5-month history of a growing mass on her right cheek. She did not complain of local pain, headache, hearing difficulty, or tinnitus. CT and MRI showed a dense calcified mass and F-18 fluorodeoxyglucose (FDG) PET demonstrated intense accumulation in the mass. Resection of the mass was performed and it was histologically diagnosed as idiopathic tumoral calcinosis.

Hepatic Encephalopathy Secondary to Intrahepatic Portosystemic Venous Shunt: Balloon-Occluded Retrograde Transvenous Embolization with n-Butyl Cyanoacrylate and Microcoils

We report a 70-year-old woman with hepatic encephalopathy due to an intrahepatic portosystemic venous shunt that was successfully occluded by percutaneous transcatheter embolization with n-butyl cyanoacrylate and microcoils.

Usefulness of the convexity apparent hyperperfusion sign in 123I-iodoamphetamine brain perfusion SPECT for the diagnosis of idiopathic normal pressure hydrocephalus

In BriefThis article shows that CBF-SPECT using 123I-iodoamphetamine is useful for the diagnosis of idiopathic normal pressure hydrocephalus (iNPH), focusing on the CAPPAH (convexity apparent hyperperfusion) sign. A negative CAPPAH sign in patients with MRI findings consistent with iNPH might be associated with other comorbid conditions such as Alzheimers disease, and might predict poor surgical response. The message is clinically important for neurologists and neurosurgeons.