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Futoshi Mihara

Publications and source records attributed to Futoshi Mihara.

31 records · Page 2Linked to original sources
PubMed2004

Validation of the CBF, CBV, and MTT values by perfusion MRI in chronic occlusive cerebrovascular disease: a comparison with 15O-PET.

RATIONALE AND OBJECTIVES: To evaluate the reliability of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values obtained by deconvolution algorithm perfusion-weighted MR imaging (D-PWI), we compared these values with those obtained by first-moment algorithm perfusion-weighted MR imaging (F-PWI) and 15O-PET. SUBJECTS AND METHODS: Six healthy volunteers and eleven patients with chronic occlusive cerebrovascular disease were studied with both perfusion-weighted MR imaging and 15O-PET, and region-of-interest analyses were performed. Normalization factors for CBF and CBV values obtained by D-PWI were determined as the mean values of 15O-PET divided by those of D-PWI in healthy volunteers. Then these values were used in analyzing the data of the patients. RESULTS: The MTT value obtained by D-PWI was 6.1 +/- 0.5 seconds on the non-occluded side, 6.4 +/- 0.7 seconds on the minimally to moderately stenosed side, and 6.7 +/- 1.2 seconds on the severely stenosed to occluded side. These values were significantly correlated with those obtained by F-PWI (r = 0.83; P < .001), and with those obtained by 15O-PET (r = 0.78; P < .05). However, the CBF and CBV values obtained by D-PWI did not correlate with those obtained by 15O-PET. CONCLUSION: MTT values obtained by D-PWI were reliable parameters of cerebral hemodynamics, but the CBF and CBV values obtained by D-PWI were not always reliable.

Adult↗
PubMed2004

Prevalence of stenoocclusive lesions in the renal and abdominal arteries in moyamoya disease.

OBJECTIVE: The extracranial involvement of moyamoya disease has been reported in several studies. The main purpose of this study was to determine the prevalence of stenoocclusive lesions in the renal and major abdominal arteries in moyamoya disease. MATERIALS AND METHODS: Abdominal angiography was performed in 73 patients with idiopathic moyamoya disease. The findings of abdominal angiography were retrospectively reviewed for the presence and appearance of stenosis in the renal and other major abdominal arteries. RESULTS: Four (5%) of 73 patients presented with unilateral renal artery stenosis. Three patients had moderate stenosis, and one patient had mild stenosis. In the three patients with moderate stenosis, the renal artery stenosis was located in the proximal region of the main branch. Two patients (3%) with moderate stenosis of the unilateral renal artery had renovascular hypertension. No statistically significant differences were observed in age, sex, and the cerebral angiographic stage between patients with and without renal artery stenosis. No stenosis was found in the abdominal aorta or celiac, superior mesenteric, common hepatic, splenic, and proximal common iliac arteries. No occlusions were found in any abdominal arteries. CONCLUSION: The prevalence of renal artery stenosis in patients with moyamoya disease was 5% (4/73). Involvement of the proximal region of the renal artery was dominant. No stenosis was found in other abdominal arteries.

Abdomen↗
PubMed2004

Differentiation of cavernous hemangioma from schwannoma of the orbit: a dynamic MRI study.

OBJECTIVE: The purpose of this study was to determine the capability of dynamic contrast MRI to differentiate hemangioma from schwannoma of the orbit. MATERIALS AND METHODS: Sixteen patients (three males and 13 females; mean age, 39 +/- 17.3 [SD] years; age range, 10-71 years) with unilateral orbital tumors, including eight cavernous hemangiomas and eight schwannomas, were examined. In addition to conventional MRI, we performed a dynamic contrast study (fast spin-echo sequence, 20-sec interval) after bolus administration of the contrast material (gadopentetate dimeglumine, 0.1 mmol/kg). We evaluated the features of the contrast enhancement spread pattern and the tumors' time-intensity curves. RESULTS: In the early phase, all the hemangiomas started the enhancement from one point or portion, although all the schwannomas started the enhancement from a wide area. The difference in the contrast-enhancement spread pattern features between the two types of tumors was statistically significant (p < 0.0001). The gradient of the time-intensity curve did not show a significant difference. CONCLUSION: Hemangioma and schwannoma of the orbit can be differentiated by the contrast-enhancement spread pattern on dynamic MRI.

Adolescent↗
PubMed2004

[Surgical treatment for temporal lobe epilepsy in patients over age 50 years].

We retrospectively analyzed 4 patients over age 50 (52 - 57) years with intractable medial temporal lobe epilepsy(MTLE) who underwent the anterior temporal lobectomy with hippocampectomy. Case 1 had MTLE with old brain abscess in the left lateral temporal lobe and Cases 2 - 4 had MTLE with histologically verified hippocampal sclerosis. In Cases 2 - 4, although the onset of seizures occurred 26 to 37 years prior to the time of surgery, there was no mental problem (IQ = 87 - 100). In Cases 1, chronic invasive electrocorticography recording using subdural electrodes was obtained, while in Case 2 - 4, the epileptogenic region was defined by noninvasive preoperative evaluation. Postoperatively, all patients obtained a meaningful improvement, becoming either free from seizures or only experiencing a rare seizure, and returned to work or usual activities without surgical complications. Surgery for MTLE appears to be effective for older individuals and carries a small risk of postoperative complications.

Anterior Temporal Lobectomy↗
PubMed2003

Semi-quantitative CBF and CBF ratios obtained using perfusion-weighted MR imaging.

To clarify the utility of semi-quantitative cerebral blood flow (CBF) measurements using perfusion-weighted MR imaging (PWI), a comparison of this method with quantitative CBF obtained using PET was conducted in 10 patients with chronic occlusive cerebrovascular disease and unilateral occlusion of the cerebral artery. Semi-quantitative CBF obtained using PWI and quantitative CBF obtained using PET showed no statistically significant correlation. The CBF ratios of the affected side relative to the contralateral unaffected side obtained using PWI and PET were 0.94 +/- 0.22 and 0.88 +/- 0.19, respectively. A statistically significant positive correlation was obtained between these ratios (p < 0.01). The CBF ratio, but not the semi-quantitative CBF, obtained using PWI has a potential to detect changes in the CBF.

Adolescent↗
PubMed2003

Reliability of mean transit time obtained using perfusion-weighted MR imaging; comparison with positron emission tomography.

The purpose of this project was to assess the reliability of the cerebral mean transit time (MTT) obtained using perfusion-weighted MR imaging by comparing it with the MTT obtained when performing positron emission tomography (PET). Ten patients with chronic occlusive cerebrovascular disease were investigated. They had either unilateral internal carotid artery occlusion or middle cerebral artery occlusion. The regions-of-interest were placed in non-infarcted areas within the territory of the middle cerebral artery on the affected side. Control regions-of-interest were placed in mirrored regions of the contralateral side. Linear regression analyses were performed using the parameters of the MTT obtained with perfusion-weighted MR imaging and the MTT, cerebral blood flow, vascular reactivity, and oxygen extraction fraction obtained with PET. The respective MTTs of the affected and non-affected sides obtained with perfusion-weighted MR imaging versus those with PET were 7.3 +/- 2.2 s and 6.0 +/- 1.2 s versus 8.2 +/- 3.0 s and 6.4 +/- 1.7 s. The MTT obtained using perfusion-weighted MR imaging and PET demonstrated statistically significant correlation (r = 0.87, p < 0.0001). The MTT obtained with perfusion-weighted MR imaging correlated statistically with cerebral blood flow (r = -0.74, p < 0.001), vascular reactivity (r = -0.73, p < 0.001) and oxygen extraction fraction (r = 0.61, p < 0.01). Similarly, the MTT obtained using PET statistically correlated with cerebral blood flow (r = -0.78, p < 0.0001), vascular reactivity (r = -0.51, p < 0.05) and oxygen extraction fraction (r = 0.68, p < 0.01). The reliability of the MTT obtained using perfusion-weighted MR imaging appears to be approximately equal to that obtained with positron emission tomography.

Adolescent↗
PubMed2003

High b value diffusion-weighted imaging is more sensitive to white matter degeneration in Alzheimer's disease.

It has been reported that diffusion-weighted imaging (DWI) can detect white matter degeneration in the Alzheimer's disease (AD) brain. We hypothesized that imaging of the slow diffusion component using high b value DWI is more sensitive to AD-related white matter degeneration than is conventional DWI, and therefore we studied the effects of high b value on lesion-to-normal contrast and contrast-to-noise ratio (CNR). Seven AD patients and seven age-matched normal subjects were studied with full-tensor DWI at three different b values (1000, 2000, and 4000 s/mm(2)) without changing echo time or diffusion time, and the mean diffusivities in the parietal and occipital regions were measured. Statistical analyses revealed that use of higher b values significantly improves both lesion-to-normal contrast and CNR. We concluded that high b value DWI is more sensitive to AD-related white matter degeneration than is conventional DWI.

Aged↗
PubMed2002

Diffusion tensor in posterior cingulate gyrus: correlation with cognitive decline in Alzheimer's disease.

To determine whether the diffusion abnormalities in brains with Alzheimer's disease (AD) correlate with disease severity, we studied 34 AD patients using diffusion tensor MRI. Mean diffusivity and fractional anisotropy (FA) as well as three eigenvalues (lambda1, lambda2, and lambda3) of the diffusion tensor of the posterior cingulate white matter correlated with the Mini-Mental State Examination (MMSE) score. The mean diffusivity and the three eigenvalues showed significant correlation with the MMSE score. On the other hand, no significant correlation was seen between the FA and MMSE score. Our results suggested that mean diffusivity and the eigen-values, but not FA, reflect progression of AD-related histopathlogical changes in the posterior cingulate white matter and may be useful biological indices to monitor AD.

Aged↗
PubMed2002

MR relative cerebral blood flow mapping of Alzheimer disease: correlation with Tc-99m HMPAO SPECT.

RATIONALE AND OBJECTIVES: To evaluate the value of magnetic resonance (MR) perfusion imaging for diagnosis of Alzheimer disease (AD), the authors compared relative cerebral blood flow (CBF) maps obtained with MR perfusion imaging and technetium-99m hexamethyl-propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) in patients with AD. MATERIALS AND METHODS: Eight patients with AD were studied with MR perfusion imaging and HMPAO SPECT. The relative CBF maps from the two techniques were spatially coregistered, and relative CBF values in 13 cerebral gray matter regions (total, 26 regions of interest) were compared with regression analysis. To evaluate the degree of deviation of each brain region from the regression line, a P value for the residual was calculated for each region. RESULTS: A significant overall correlation was seen between the relative CBF values produced by the two techniques (r = .68, P < .0001). Smaller P values for the residuals were obtained in the anterior cingulate cortex (P = .05) and posterior cingulate cortex (P < .001), indicating larger deviations in these regions. When data from these two regions were eliminated, the correlation coefficient rose to 0.80 (P < .0001). CONCLUSION: Despite fairly large discrepancies in the anterior and posterior cingulate cortices, the relative CBF map obtained with MR imaging is generally in close agreement with the HMPAO SPECT map, suggesting that MR perfusion imaging can provide clinically useful information regarding CBF abnormalities in patients with AD.

Adult↗
PubMed2002

[A case of medial temporal lobe epilepsy associated with occult focal cortical dysplasia in the lateral temporal neocortex].

A 29-year-old male with medial temporal lobe epilepsy(MTLE) was revealed to have "occult" focal cortical dysplasia(FCD) in the lateral temporal neocortex. He had no history of febrile convulsion and developed complex partial seizure at the age of 14 year, which became intractable. Although MRI failed to reveal structural abnormality in the temporal lobe, even retrospectively, the findings of non-invasive preoperative examination, such as video-EEG monitoring and interictal ECD-SPECT and FDG-PET, were consistent with those of the left MTLE. Intraoperative electrocorticography(ECoG) demonstrated almost continuous paroxysmal activities on the anterior part of the inferior temporal gyrus(ITG). Anterior temporal lobectomy(ATL) with hippocampectomy was performed. Histological examination revealed FCD in the small area with 0.8 mm in diameter of the resected ITG. In the ATL without preoperative invasive examination such as chronic subdural electrode recording, intraoperative ECoG recording is mandatory.

Adult↗
PubMed2002

[Fetal germinal matrix and intraventricular hemorrhage associated with periventricular leukomalacia].

Subependymal germinal matrix hemorrhage with intraventricular hemorrhage(SEIVH) is a common complication associated with delivery in preterm neonates but has rarely been observed in the fetus. We report a fetus with SEIVH, hydrocephalus and periventricular leukomalacia(PVL). Although this fetus had uneventful prenatal periods, transabdominal ultrasound examination(US) at 33 weeks of pregnancy revealed SEIVH and hydrocephalus, and MRI at 36 weeks did associated PVL. While no events reported that could explain the onset of SEIVH, PVL was considered to be the results of anoxic events associated with SEIVH. In addition to US, information provided by fetal MRI, especially T 2-weighted image, permits a better understanding of the pathophysiology of fetal SEIVH with PVL.

Adult↗