Biomedical subjects

H Isoda

Publications and source records attributed to H Isoda.

80 records · Page 5Linked to original sources

PubMedDate not supplied

MR angiography of the coronary arteries.

Coronary vessels have been the most difficult regions to demonstrate by magnetic resonance (MR) imaging because of their motion with respiration and heart beat. MR coronary angiography may be utilized for evaluation of the coronary arteries. The purposes of the present study were to demonstrate coronary arteries in normal volunteers by using a fast MR imaging technique and to evaluate the feasibility of this imaging technique. Thirteen healthy volunteers in a prone position were imaged with a 1.5 Tesla unit by using an ECG-gated fat-suppressed Turbo fast low-angle shot (FLASH) sequence with k-space segmentation. The imaging time for one slice was approximately 15-23 seconds, within one breath-hold. The left main coronary trunk (LMT), left anterior descending (LAD), circumflex (LCX), and right coronary (RC) arteries were imaged at rates of 92.3, 100, 92.3, and 84.6%, respectively. Diameters of the LMT, LAD, LCX, and RC in proximal portions were 5.2 +/- 1.1, 3.2 +/- 1.3, 2.2 +/- 0.6, and 4.0 +/- 1.6 mm, respectively. The segmented Turbo FLASH technique was able to image the normal coronary arteries, and is a promising method by which to evaluate coronary artery diseases.

Adult↗

PubMedDate not supplied

Pulmonary MR angiography: a comparison of 2D and 3D time-of-flight.

OBJECTIVE: To compare two-dimensional (2D) time-of-flight (TOF) MR angiography and three-dimensional (3D) TOF MR angiography for visualization of pulmonary arteries and to determine whether pulmonary veins can be viewed selectively. MATERIALS AND METHODS: Imaging was performed using a 1.5 T superconducting MR system with a body coil. Three kinds of 2D TOF MR angiography were compared in four normal volunteers: using a 2D fast low angle shot (FLASH) without cardiac gating and both with and without breath-holding and using a T2-weighted TurboFLASH with cardiac gating and breath-holding. Two-dimensional TOF MR angiography using a T2-weighted TurboFLASH with cardiac gating and breath-holding and 3D TOF MR angiography using fast imaging with steady precession with neither cardiac gating nor breath-holding were compared in four other normal volunteers. Two-dimensional TOF MR venography with a presaturation pulse to suppress artery signals was evaluated in another four normal volunteers. RESULTS: Three-dimensional TOF MR angiography appeared to be better than 2D TOF MR angiography for delineating pulmonary arteries in the volunteers. The third order branches of peripheral pulmonary veins were distinguishable on 2D TOF MR venography using a presaturation pulse. CONCLUSION: Three-dimensional pulmonary TOF MR angiography is useful in demonstrating pulmonary arteries whereas 2D TOF MR venography with a presaturation pulse is useful in showing pulmonary veins.

Adult↗

PubMedDate not supplied

Preliminary study of pulmonary three-dimensional time-of-flight MR angiography with breath-holding using a contrast medium.

Pulmonary three-dimensional (3D) time-of-flight (TOF) MR angiography with breath-holding using a paramagnetic contrast medium and a 1.5 Tesla superconducting MR system was performed on a volunteer and five patients with hilar or mediastinal tumors in order to visualize the main pulmonary arteries. Six MR scans (one before and five after a Gd-DTPA injection) were obtained using fast imaging with a steady-state precession (FISP) sequence while the subjects held their breath. The acquisition time was 21 seconds, and images were obtained every 30 seconds. In the normal volunteer, the pulmonary MR angiogram obtained in the first postcontrast scan was successful in visualizing the main pulmonary artery, and its right and left branches to the level of the lobar branches. In the five patients, at the first postcontrast scanning, the pulmonary arteries had higher signal intensities than the surrounding structures. Therefore, during this imaging period, most tumors could be clearly distinguished from vessels. In images made much later after contrast medium injection, the pulmonary arteries could not be distinguished from the others. Pulmonary 3D TOF MR angiography with breath-holding using a contrast medium is very useful in demonstrating pulmonary vessels and tumors.

Adult↗

PubMedDate not supplied

Meningeal hemangiopericytoma metastatic to the heart.

We report for the first time the metastasis of intracranial hemangiopericytoma to the heart. In evaluating cardiac conditions, MRI provided useful information regarding the location and features of paracardiac tumors.

Female↗

PubMedDate not supplied

Pituitary prolactinoma mimicking tumor originating from the sphenoid sinus or clivus.

We report a case of a pituitary prolactinoma mimicking a sphenoid sinus or clival tumor. On magnetic resonance (MR) images, a soft tissue mass located inferior to the apparently normal pituitary gland, and occupied the posterior third of the sphenoid sinus and eroded the upper portion of the clivus. It had iso- to low intensity on the T1-weighted image, and slightly high intensity on the T2-weighted image. Careful observation revealed that the floor of the sella turcica was not identified and there was sulcus formation between the tumor and clivus, probably suggesting extraclival tumor, pituitary tumor. Transsphenoidal tumor resection and histopathological study revealed that it was a prolactinoma.

Cranial Fossa, Posterior↗

PubMedDate not supplied

Evaluation of reconstructed hepatic veins with breath-hold 2D time-of-flight MR venography.

PURPOSE: The purpose of this study was to assess the ability of magnetic resonance (MR) venography to evaluate the patency of reconstructed hepatic veins after surgery. PATIENTS AND METHODS: Five normal volunteers with normal hepatic veins and eight patients who underwent reconstruction of the hepatic veins after resection of hepatic tumors were included. All subjects underwent breath-hold two-dimensional (2D) time-of-flight MR venography using a fast low angle shot (FLASH) technique with a 1.5 Tesla magnet. The initial imaging plane was coronal, and sagittal and/or transverse planes were added when necessary. Data were postprocessed with a maximum intensity projection (MIP) algorithm. In six patients, the MR findings were verified by iodinated hepatic venography. RESULTS: The confidence level increased when patency was evaluated using a combination of MIP and source images or other imaging planes compared with the use of MIP images alone (3.0 to 3.6, p < 0.05). A signal drop near the orifice at the inferior vena cava was observed in three normal patients. The severity of stenosis was overestimated by MR venography in five patients. Obstruction was correctly suggested in one patient. CONCLUSION: Although 2D time-of-flight MR venography overestimated stenosis of the hepatic vein at the site of connection, it might provide information on the patency of reconstructed hepatic veins especially when more than one orthogonal plane is used and both MIP and source images are evaluated.

Adult↗

PubMedDate not supplied

MR imaging of acute transverse myelitis (myelopathy).

The purpose of our study was to review the MR characteristics of acute transverse myelitis (ATM) retrospectively and to review the literature. The subjects were 26 patients (two males, 24 females). MR examinations were carried out using a 1.5 Tesla scanner. MR imaging in eight of 16 lesions in nine subjects with preexisting MS showed multiple areas of increased signal intensity on T2-weighted sagittal images, and 11 lesions had no cord swelling. Twelve of 16 lesions showed heterogeneous enhancement. MR imaging in 10 of 13 lesions in 12 subjects with preexisting HTLV-1 infection, mycoplasma pneumonia infection, hepatitis B vaccinations, and uncertain etiologies revealed fusiform increased signal intensity areas on T2-weighted sagittal images and cord swelling. Seven of 11 lesions in the patients who underwent injection of contrast medium showed heterogeneous enhancement, whereas others showed no enhancement. MR examination is recommended for the evaluation of ATM.

Acute Disease↗

PubMedDate not supplied

In-111 labeled leukocyte scintigraphy in patients with suspected inflammation after failed antibiotic therapy.

In-111 labeled leukocyte scintigraphy (In-111 WBC scan) was performed in 16 patients with inflammation suspected on the basis of laboratory findings, symptoms, and diagnostic imaging, but who had failed antibiotic therapy. In-111 WBC scans revealed an abnormal focus of radiotracer activity (positive scans) in five of 16 patients. No correlation was found between the peripheral WBC count and accumulation of In-111 WBC. Inflammatory disease suspected on the basis of the CRP level should be considered when In-111 WBC scanning results in negative findings. Our results indicated that In-111 WBC scanning has low sensitivity after antibiotic therapy. Selection of patients on the basis of persistent elevation of CRP may be valuable.

Adolescent↗