Biomedical subjects

B Holshouser

Publications and source records attributed to B Holshouser.

5 recordsLinked to original sources

PubMed1995

Magnetic resonance imaging as a monitor of changes in the irradiated rat brain. An aid in determining the time course of events in a histologic study.

RATIONALE AND OBJECTIVES: Optimal dose schedules and total dose of ionizing radiation for human central nervous system malignancy are not known. An animal model has been developed for the investigation of rat central nervous system response to proton irradiation using magnetic resonance imaging (MRI). A clinical MRI device was used to monitor the response of the rat brain after irradiation as a possible indicator for histologic injury as a function of time and dose. METHODS: Single-dose fractions of protons were delivered to the left brain of 25 adult Sprague-Dawley rats. T1- and T2-weighted images were obtained using a 1.5-T MRI device via a 12-cm diameter coil at 4- to 6-week intervals after irradiation. Coronal images were evaluated by visual inspection and relaxation maps comparing the control and irradiated hemispheres. Histologic review was conducted on all rats' brains after death. RESULTS: Proton irradiation was delivered successfully to only the left brain of the animals. Histologic review confirms the location and extent of tissue damage demonstrated on MRIs obtained in vivo. Statistically significant differences were seen in the T2-weighted relaxation times in the irradiated cerebral hemisphere compared with the unirradiated hemisphere. CONCLUSION: The proton hemibrain rat model can be used to test treatment schedules of irradiation for central nervous system response using MRI to noninvasively document early and late effects within the same animal.

Animals↗

PubMed1991

[Magnetic resonance tomography of Fallot's tetralogy].

We present four patients with tetralogy of Fallot, imaged with magnetic resonance. MRI is useful in clearly depicting the dilated ascending aorta, the infundibular stenosis, ventricular septal defect, right ventricular hypertrophy and dilated bronchial arteries. The pulmonary outflow tract can be visualized better with MR imaging than with ultrasound.

Adolescent↗

PubMed1987

Magnetic resonance imaging of the normal carotid bifurcation.

A Siemens 0.5 Tesla Magnetic Resonance Imaging (MRI) system was used with the saddle head coil and transverse scout localization for imaging 10 normal cervical carotid artery bifurcations in the sagittal plane. Good to excellent visualization of the flow voids and vessel contours was accomplished in all cases. Careful technique and patient cooperation are required.

Adult↗

PubMed1981

A precision pump for simulated cardiographic studies.

A system simulating physiologic and pathologic changes in left-ventricular volume is presented. Its purpose is to provide a model to establish the accuracy of current equipment for assessing a heart's performance where the actual volume and size are measurable. The versatility of the model allows a wide range of variability of various parameters for simulation of many clinical situations.

Cardiac Output↗

PubMedDate not supplied

The bright choroid plexus on MR: CT and pathologic correlation.

Fourteen patients studied with MR imaging were found, incidentally, to have unusually bright, large choroid plexus glomera on T2-weighted sequences. A group of 167 patients was then examined retrospectively for size and intensity of the choroid plexus glomera on T2-weighted images. In the latter group of 167 patients, 66 (39.5%) had bright choroid plexus glomera. Of those who had bright choroid plexus glomera, eight of the 14 initial group and 11 of the 66 patients studied retrospectively had previous CT scans. The typical CT appearance of these bright glomera consisted of nonenhancing central regions of low (but not negative) attenuation with peripheral calcifications in the majority. The remainder showed noncalcified glomera. Fifty-two glomera were obtained at autopsy and examined retrospectively. Eight showed small, variably sized masses with lipid deposits, neuroepithelial microcysts, and peripheral psammoma body calcifications. One patient who died had a bright choroid plexus glomus on MR, and his glomera showed the same pathologic findings. The autopsy findings were believed to be typical pathologically for early xanthogranulomata formation. These early xanthogranulomatous changes appear to be of little clinical significance but must be differentiated from other lesions that can produce bright or enlarged choroid plexus glomera on MR.

Adolescent↗