Hiroyasu Takeda

Visualization of hemodynamics in intracranial arteries using time-resolved three-dimensional phase-contrast MRI.

To visualize the hemodynamics of the intracranial arteries using time‐resolved three‐dimensional phase‐contrast (PC)‐MRI (4D‐Flow).

Proton magnetic resonance spectroscopy of the lenticular nuclei in bipolar I affective disorder

Proton magnetic resonance spectroscopy (1H-NMS) was used to examine the ratio of choline-containing compound (Cho) to creatine (Cr) in the basal ganglia. Subjects comprised 10 bipolar I affective disorder patients and 10 healthy control subjects. No significant difference was found in the Cho/Cr, N-acetyl-aspartate (NAA)/Cr, or NAA/Cho ratios between bipolar patients and control subjects. Within the bipolar group, negative correlations emerged between the NAA/Cr ratio in the right lenticular nuclei and both age at onset and age at the time of study. The results suggest that a late onset of illness and older age are associated with neuronal cell loss in the right lenticular nuclei in bipolar patients.

MRA of intracranial aneurysm models: a comparison of contrast-enhanced three-dimensional MRA with time-of-flight MRA.

PURPOSE The purpose of our study was to compare contrast-enhanced 3D MR angiography (MRA) using ultrafast spoiled gradient-recalled acquisition in the steady state (SPGR) with 2D and 3D time-of-flight (TOF) MRA for visualization of intracranial lateral saccular aneurysm models. METHOD We used lateral saccular aneurysm models with a height of 10 mm and neck sizes of 2.5 and 10 mm. Imaging was performed using a 1.5 T MR system with a head coil. Contrast-enhanced 3D MR angiograms were obtained using 3D ultrafast SPGR sequence with and without the MR Smartprep technique. Two-dimensional and 3D TOF MR angiograms were also obtained. RESULTS Contrast-enhanced multiphase 3D MR angiograms taken every 5 s after injection of contrast medium proved superior to the other MRA techniques for delineating lateral saccular aneurysm models. Contrast-enhanced 3D MRA images taken with inadequate delay after MR Smartprep trigger showed poor visualization of the aneurysm model. CONCLUSION Use of contrast-enhanced multiphase 3D MRA with ultrafast SPGR with shorter TR and TE resulted in clear images of the lateral saccular aneurysm model.

Proton magnetic resonance spectroscopy of lenticular nuclei in obsessive-compulsive disorder.

Magnetic resonance spectroscopy (MRS) is a safe and non-invasive technique for the in vivo study of brain chemistry and metabolism. As such, it is highly applicable to the study of living brain tissue in psychiatric diseases. Several neuropathological and neuroimaging studies have suggested that abnormalities of the basal ganglia nuclei might be implicated in patients with obsessive-compulsive disorder (OCD). In the present study, we performed proton [1H]MRS of the lenticular nuclei in 12 patients with OCD and 12 healthy normal comparison subjects. The peaks of N-acetyl-aspartate (NAA), creatine (Cr), and choline-containing compounds (Cho) were measured. No differences between OCD patients and normal subjects were found in the NAA/Cr, Cho/Cr and NAA/Cho ratios. Our results suggest the normal viability of neuronal cells, as indicated by the quantification of NAA, Cr and Cho in the lenticular nuclei of patients with OCD.

Dynamic gadolinium-enhanced MR imaging of pituitary adenomas: usefulness of sequential sagittal and coronal plane images.

Dynamic magnetic resonance (MR) imaging for pituitary adenomas is usually performed in a coronal direction; however, small lesions between slices, or lesions located at the anterior or posterior aspect of the pituitary gland might be overlooked on MR images in only the coronal direction. The purpose of our study was to evaluate whether consecutive dynamic MR images in the coronal and sagittal planes improve detection of pituitary adenomas. Eighteen patients with pituitary microadenomas and nine with healthy pituitary glands were included in this study. MR images were performed with 1.5 T superconductive units and commercially-available head coils. After a 5 ml gadolinium contrast injection, eight serial dynamic sagittal images were obtained. Within 3 or 6 min, this was followed by a 10-15 ml gadolinium injection and acquisition of eight serial dynamic coronal images. Dynamic MR images and conventional noncontrast- and contrast-enhanced sagittal and coronal T1-weighted images were evaluated independently in a blind fashion by two neuroradiologists regarding the depiction of pituitary microadenomas. The sensitivities of dynamic enhanced MR imaging in the detection of microadenomas were 61.1% in sagittal direction, 72.2% in coronal direction respectively, and were superior to those of conventional noncontrast- and contrast-enhanced T1-weighted imaging (22.2-50%). The sensitivity of a combination of sagittal and coronal dynamic enhanced MR imaging for the detection of microadenomas was 88.9% and was superior to those of conventional noncontrast- and contrast-enhanced T1-weighted imaging combining sagittal and coronal directions (61.1%, 61.1%) (P<0.05, P<0.05, respectively). The specificity and accuracy of dynamic enhanced MR imaging with combination of sagittal and coronal images was 88.9% respectively. Dynamic gadolinium-enhanced MR imaging, especially using both sagittal and coronal planes, was concluded to be useful for the detection of pituitary microadenomas.

Assessment of a potential tumor-seeking manganese metalloporphyrin contrast agent in a mouse model.

The performance of a newly developed potential tumor‐seeking magnetic resonance (MR) contrast agent α‐Aqua‐13,17‐bis(1‐carboxypropionyl) carbamoylethyl‐3,8‐bis(1‐phenethyloxyethyl)‐β‐hydroxy‐2,7,12,18‐tetramethyl‐porphyrinato manganese (III) (HOP‐8P) was tested using a mouse model. Tumor‐bearing (SCC‐VII) mice were imaged using a 1.5T MR imager before and after intravenous administration of 0.1 mmol/kg of HOP‐8P. A biodistribution analysis was performed using an optical emission spectrometer. Significant enhancement of the transplanted tumor was observed in MR images 24 h after intravenous injection of HOP‐8P. The biodistribution assessment of manganese also correlated with the results of the imaging study. During the 24‐h period following contrast administration, HOP‐8P was consistently cleared from the circulation, liver, kidneys, and muscle; however, it was progressively accumulated within the tumor. HOP‐8P is a promising tumor‐seeking metalloporphyrin MR contrast agent with a wide imaging window. Magn Reson Med 47:549–553, 2002.

Proton magnetic resonance spectroscopy of lenticular nuclei in simple schizophrenia.

1. The lenticula nuclei have been suggested to be the site of structural and functional abnormalities in schizophrenia. 2. Recently, several studies involving proton magnetic resonance spectroscopy (1H MRS) showed that the ratio of N-acetyl-aspartate (NAA) to choline-containing compounds (Cho) was significantly reduced in the basal ganglia region in patients with schizophrenia. 3. Simple schizophrenia is characterized by social withdrawal and affective flattening, but not by prominent catatonic, hebephrenic or paranoid features. 4. We studied, using 1H MRS, the lenticula nuclei of 10 patients with simple schizophrenia, and 10 age- and sex-matched healthy controls. 5. No differences between the patients and the controls were found in any of the measured ratios, i.e. Cho/Cr, NAA/Cr and NAA/Cho. 6. Our results suggest the normal viability of neuronal cells, as found on quantification of NAA, Cr and Cho, in the lenticular nuclei of patients with simple schizophrenia. 7. The pathophysiology of simple schizophrenia may be different from those of other types of schizophrenia.

Tumour enhancement with newly developed Mn-metalloporphyrin (HOP-9P) in magnetic resonance imaging of mice.

The purpose of the study is to evaluate the tumour enhancing characteristics and biodistribution of a newly developed metalloporphyrin derivative, HOP-9P (13, 17-bis (1-carboxypropionyl) carbamoylethyl-3, 8-bis (1-phenylpropyloxyethyl)-2,7,12,18-tetra- methyl-porphynato manganese (III)). Seven mice bearing SCC VII tumours were imaged using T1-weighted conventional spin echo magnetic resonance images before and 5 min, 2 h and 24 h after intravenous injection of 0.1 mmol/kg of HOP-9P. For the acquired images, signal intensities of the tumour, muscle and oil-phantom were measured. Then, tumor/oil and tumor/muscle signal intensity ratios were calculated. Nineteen mice were sacrificed before or after the administration of HOP-9P (at 5 min, 2 h and 24 h), and the biodistribution of manganese in the tumour, muscle, liver, blood and kidneys was measured using optical emission spectrometers and was expressed as micrograms of manganese per gram of tissue. The tumour/muscle signal intensity ratio at 24 h (3.18 ± 0.34) was significantly higher than precontrast ratio (1.77 ± 0.20) (P < 0.05). The biodistribution assessment of manganese demonstrated that HOP-9P gradually and consistently accumulated in the tumour to reach the highest concentration at 24 h (3.49 ± 1.22 μ gMn/g). It is concluded that HOP-9P is a potential tumour-specific MR contrast agent.

Metabolite Alterations in Basal Ganglia Associated with Psychiatric Symptoms of Abstinent Toluene Users: A Proton MRS Study

Long-term toluene abuse causes a variety of psychiatric symptoms. However, little is known about abnormalities at the neurochemical level in the living human brain after long-term exposure to toluene. To detect neurochemical changes in the basal ganglia of subjects with a history of long-term toluene use, proton magnetic resonance spectroscopy (1H MRS) was performed in 12 abstinent toluene users and 13 healthy comparisons with no history of drug abuse. N-acetylaspartate (NAA), creatine plus phosphocreatine (Cr+PCr), choline-containing compounds (Cho), and myo-inositol (MI) levels were measured in the left and right basal ganglia. The Cho/Cr+PCr ratio, a marker of membrane metabolism, was significantly increased in the basal ganglia of toluene users in comparison to that of the control subjects. Furthermore, the increase in the Cho/Cr+PCr ratio was significantly correlated with the severity of residual psychiatric symptoms. These findings suggest that long-term toluene use causes membrane disturbance in the basal ganglia, which is associated with residual psychiatric symptoms that persist even after long-term abstinence from toluene use.

Tumor enhancement using Mn-metalloporphyrin in mice: Magnetic resonance imaging and histopathologic correlation

To determine the signal enhancement characteristics of tumors after administration of a metalloporphyrin derivative, HOP‐9P (13, 17‐bis (1‐carboxypropionyl) carbamoylethyl‐3, 8‐bis (1‐phenylpropyloxyethyl)‐2, 7, 12, 18‐tetramethyl‐porphyrinato manganese (III)) and to determine whether HOP‐9P is tumor‐necrosis specific.