Atsushi Nakanishi

White Matter Alteration of the Cingulum in Parkinson Disease with and without Dementia: Evaluation by Diffusion Tensor Tract–Specific Analysis

BACKGROUND AND PURPOSE: In PD, the neurodegenerative process begins in the brain stem and extends to the limbic system and finally into the cerebral cortex. We used diffusion tensor tractography to investigate the FA of the cingulate fiber tracts in patients with PD with and without dementia. MATERIALS AND METHODS: Fifteen patients with PD, 15 patients with PDD, and 15 age-matched healthy controls underwent diffusion tensor imaging with a 3T MR imager. Diffusion tensor tractography images of the anterior and posterior cingulate fiber tracts were generated. Mean diffusivity and FA were measured along the tractography of the anterior and posterior cingulate fiber tracts. One-way ANOVA with the Scheffé post hoc test was used to compare results among the groups. RESULTS: FA was significantly lower in patients with PDD than in healthy controls in both the anterior and the posterior cingulate fiber tracts (P = .003, P = .015) and significantly lower in patients with PD than in healthy controls (P = .003) in the anterior cingulate fiber tract. There were no significant mean diffusivity differences among the groups. MMSE and FA values of the anterior cingulate fiber tracts in patients with PDD were significantly correlated (r = 0.633, P < .05). CONCLUSIONS: The reduced FA in patients with PD and PDD might reflect neuropathologic changes such as Lewy body pathology in the cingulate fibers. This abnormality might contribute to the dementing process in PD.

Diffusional kurtosis imaging of cingulate fibers in Parkinson disease: Comparison with conventional diffusion tensor imaging

OBJECTIVE The pathological changes in Parkinson disease begin in the brainstem; reach the limbic system and ultimately spread to the cerebral cortex. In Parkinson disease (PD) patients, we evaluated the alteration of cingulate fibers, which comprise part of the limbic system, by using diffusional kurtosis imaging (DKI). METHODS Seventeen patients with PD and 15 age-matched healthy controls underwent DKI with a 3-T MR imager. Diffusion tensor tractography images of the anterior and posterior cingulum were generated. The mean kurtosis (MK) and conventional diffusion tensor parameters measured along the images in the anterior and posterior cingulum were compared between the groups. Receiver operating characteristic (ROC) analysis was also performed to compare the diagnostic abilities of the MK and conventional diffusion tensor parameters. RESULTS The MK and fractional anisotropy (FA) in the anterior cingulum were significantly lower in PD patients than in healthy controls. The area under the ROC curve was 0.912 for MK and 0.747 for FA in the anterior cingulum. MK in the anterior cingulum had the best diagnostic performance (mean cutoff, 0.967; sensitivity, 0.87; specificity, 0.94). CONCLUSIONS DKI can detect alterations of the anterior cingulum in PD patients more sensitively than can conventional diffusion tensor imaging. Use of DKI can be expected to improve the ability to diagnose PD.

Posterior hypoperfusion in Parkinson's disease with and without dementia measured with arterial spin labeling MRI.

To determine whether quantitative arterial spin labeling (ASL) can be used to evaluate regional cerebral blood flow in Parkinsons disease with dementia (PDD) and without dementia (PD).

Relationship between cognitive impairment and white-matter alteration in Parkinson’s disease with dementia: tract-based spatial statistics and tract-specific analysis

ObjectivesWe investigated the relationship between white-matter alteration and cognitive status in Parkinson’s disease (PD) with and without dementia by using diffusion tensor imaging.MethodsTwenty PD patients, 20 PDD (Parkinson’s disease with dementia) patients and 20 age-matched healthy controls underwent diffusion tensor imaging. The mean diffusivity and fractional anisotropy (FA) map of each patient group were compared with those of the control group by using tract-based spatial statistics. Tractography images of the genu of the corpus callosum fibre tracts were generated, and mean diffusivity and FA were measured.ResultsFA values in many major tracts were significantly lower in PDD patients than in control subjects; in the prefrontal white matter and the genu of the corpus callosum they were significantly lower in PDD patients than in PD patients. There was a significant correlation between the Mini-Mental State Examination (MMSE) scores and the FA values of the prefrontal white matter and the genu of the corpus callosum in patients with PD.ConclusionsOur study shows a relationship between cognitive impairment and alteration of the prefrontal white matter and genu of the corpus callosum. These changes may be useful in assessing the onset of dementia in PD patients.Key Points• Dementia is a common and important non-motor sign of Parkinson’s disease (PD).• The neuropathological basis of dementia in PD is not clear.• DTI shows abnormalities in the prefrontal white matter in PD with dementia.• Prefrontal white matter alteration may be useful biomarker of dementia in PD.

White Matter Alteration in Metabolic Syndrome Diffusion tensor analysis

OBJECTIVE We explored the regional pattern of white matter alteration in subjects with metabolic syndrome. We also investigated whether white matter alteration was correlated with BMI. RESEARCH DESIGN AND METHODS Seven middle-aged men with metabolic syndrome and seven without metabolic syndrome underwent diffusion tensor imaging with a 3T magnetic resonance imaging imager. We analyzed the fractional anisotropy (FA) values by using a tract-based spatial statistics technique (whole-brain analysis). We subsequently focused on measuring the mean FA values of the right inferior fronto-occipital fasciculus (IFOF) of all subjects by tract-specific analysis (regional brain analysis). We used a Pearson correlation coefficient to evaluate the relationship between BMI and mean FA values of the right IFOF. RESULTS In the whole-brain analysis, subjects with metabolic syndrome had significantly lower FA values than control subjects in part of the right external capsule (part of the right IFOF), the entire corpus callosum, and part of the deep white matter of the right frontal lobe. In the regional brain analysis, the mean FA value of the right IFOF was 0.41 ± 0.03 for subjects with metabolic syndrome and 0.44 ± 0.05 for control subjects. A significant negative correlation was observed between BMI and FA values in the right IFOF (r = −0.56, P < 0.04). CONCLUSIONS Our results show that microstructural white matter changes occur in patients with metabolic syndrome. FA values may be useful indices of white matter alterations in patients with metabolic syndrome.

Adrenal schwannoma: CT and MRI findings

We report a case of adrenal schwannoma, an extremely rare retroperitoneal neoplasm. The patient was a 33-year-old man who presented with an abdominal mass that was discovered at abdominal sonography. Computed tomography showed an 8-cm well-circumscribed homogeneous mass that enhanced slightly after intravenous administration of contrast material. Magnetic resonance imaging showed low signal intensity on T1-weighted images and heterogeneously high signal intensity on T2-weighted images. Although these imaging findings are nonspecific, adrenal schwannomas should be included in the differential diagnosis of solid nonfunctioning adrenal tumors.

Japanese consensus guidelines for pediatric nuclear medicine. Part 1: Pediatric radiopharmaceutical administered doses (JSNM pediatric dosage card). Part 2: Technical considerations for pediatric nuclear medicine imaging procedures.

Abstract The Japanese Society of Nuclear Medicine has recently published the consensus guidelines for pediatric nuclear medicine. This article is the English version of the guidelines. Part 1 proposes the dose optimization in pediatric nuclear medicine studies. Part 2 comprehensively discusses imaging techniques for the appropriate conduct of pediatric nuclear medicine procedures, considering the characteristics of imaging in children.

Utility of time-resolved three-dimensional magnetic resonance digital subtraction angiography without contrast material for assessment of intracranial dural arterio-venous fistula

Background Intracranial dural arteriovenous fistula (DAVF) is an arteriovenous shunting disease of the dura. Magnetic resonance angiography (MRA) is expected to be a safer alternative method in evaluation of DAVF, compared with invasive intra-arterial digital subtraction angiography (IADSA). Purpose To evaluate the diagnostic use of time-spatial labeling inversion pulse (Time-SLIP) three-dimensional (3D) magnetic resonance digital subtraction angiography (MRDSA) without contrast material in six patients with DAVF. Material and Methods Images for 3D time-of-flight MRA, which has been a valuable tool for the diagnosis of DAVF but provide little or less hemodynamic information, and Time-SLIP 3D MRDSA, were acquired for each patient. The presence, side, and grade of the disease were evaluated according to IADSA. Results In all patients, the presence and side of the DAVF were correctly identified by both 3D time-of-flight MRA and Time-SLIP 3D MRDSA. Cortical reflux present in a patient with a grade 2b DAVF was not detected by Time-SLIP 3D MRDSA, when compared with IADSA findings. Conclusion Time-SLIP 3D MRDSA provides hemodynamic information without contrast material and is a useful complementary tool for diagnosis of DAVF.

Intracranial carotid calcification on CT images as an indicator of atheromatous plaque: analysis of high-resolution CTA images using a 64-multidetector scanner.

PurposeIntracranial arterial wall calcifications are frequently observed on routine head computed tomography (CT) images. The purpose of this study was to evaluate whether calcification of the intracranial carotid artery on CT images could predict atheromatous plaque and luminal stenosis.Materials and methodsA total of 259 patients were examined using three-dimensional CT angiography using high-resolution 64 detector scanners. We examined patients from the petrous portion to the top of the internal carotid arteries. We evaluated the existence of calcification and atheromatous plaque based on our criteria retrospectively. The thickness of calcification was measured in each vessel, and the shape of calcification was classified into three types.ResultsThere was low correlation between the thickness of the calcification and luminal stenosis, but the shape of the calcification corresponded well to the stenosis. The population of patients with >50% stenosis of the intracranial carotid artery differed statistically significantly for each calcification shape. There was a high negative predictive value (97.7%) in the correlation between the existence of calcification and atheromatous plaque on the multidetector CT images.ConclusionCalcification of the intracranial carotid artery on CT images shows a high negative predictive value for the existence of atheromatous plaque in the same artery. The thickness of the calcification did not correlate well with luminal stenosis, but its shape seemed to predict luminal stenosis.

Usefulness of cerebral blood flow (CBF) measurements to predict the functional outcome for rehabilitation in patients with cerebrovascular disease (CVD).

PurposeThe objectives of this study were to (1) elucidate the relationship between the mean CBF in the whole brain (Av.mCBF) before rehabilitation of CVD patients and the BI score before and after rehabilitation, (2) determine whether the efficacy of rehabilitation can be predicted by measurement of the Av.mCBF, and (3) investigate what part of the brain was most important to improving the BI score.Materials and MethodsThe Av.mCBFs in 160 patients with CVD were calculated by Patlak plots with99mTc-HMPAO before rehabilitation, and we determined the BI score before and after rehabilitation. Based on the BI scores before and after rehabilitation, patients were divided into four groups: Group A, BI=100; Group B, 80≤BI≤99; Group C, 60≤BI≤79; Group D, 0≤BI≤59. We evaluated the relationship between the Av.mCBF and BI score before and after rehabilitation.ResultsThe Av.mCBF before rehabilitation showed a tendency to be more correlated with the BI score after rehabilitation (r=0.414, p<0.0001) than before rehabilitation (r=0.272, p=0.0006). After rehabilitation, there was a tendency for the Av.mCBF value to increase in direct proportion to the BI score of the group: it was highest in Group A and lowest in Group D. The strongest correlation was found between the frontal lobe regional CBF before rehabilitation and the BI score after rehabilitation (r=0.343, p<0.0001).ConclusionsMeasurement of the Av.mCBF before rehabilitation of CVD patients will permit prediction of the efficacy of rehabilitation. Also the regional CBF of the frontal lobe is most important for improving the BI score.