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Biomedical subjects

H Kundel

Publications and source records attributed to H Kundel.

6 recordsLinked to original sources
PubMed1984

Magnetic resonance evaluation of hydronephrosis in the dog.

The ability of magnetic resonance (MR) imaging to detect and distinguish various stages of obstruction in the canine kidney was investigated. MR images were obtained at acute, subacute, and chronic stages of experimentally produced hydronephrosis. The renal cortex was distinguished from the renal medulla in the normal dog and in the acute and subacute stages of hydronephrosis. T1 relaxation times of the renal cortex and medulla were measured in vitro in 14 normal and nine experimental animals. These values were used to compute the amount of tissue contrast between the cortex and medulla and were compared with the degree of corticomedullary differentiation seen in the image. A relationship was noted between increasing T1 values and increasing water content. Corticomedullary contrast decreased with obstruction. The variation in corticomedullary image contrast may be useful for assessing the duration of hydronephrosis.

Animals↗
PubMed1984

Gadolinium enhanced nuclear magnetic resonance images of experimental brain abscess.

Gadolinium-DTPA, a paramagnetic contrast agent that distributes throughout the body in a manner similar to diatrizoate, was intravenously administered to a monkey with a hematogenously induced experimental intracranial abscess. Contrast enhanced computed tomography (CT) and gadolinium enhanced saturation-recovery nuclear magnetic resonance (NMR) were both performed immediately and repeated after a 30 min delay. The NMR images revealed marked ring enhancement at a time when CT showed a nodule. Both imaging modalities were analyzed with respect to the pathological specimen. Gadolinium-DTPA may be an effective agent for imaging alterations of the blood-brain barrier.

Animals↗
PubMedDate not supplied

Induced renal artery stenosis in rabbits: magnetic resonance imaging, angiography, and radionuclide determination of blood volume and blood flow.

To investigate the ability of MRI to detect alterations due to renal ischemia, a rabbit renal artery stenosis (RAS) model was developed. Seven rabbits had RAS induced by surgically encircling the artery with a polyethylene band which had a lumen of 1 mm, 1 to 2 weeks prior to imaging. The stenosis was confirmed by angiography, and the rabbits were then imaged in a 1.4 T research MRI unit. T1 was calculated using four inversion recovery sequences with different inversion times. Renal blood flow, using 113Sn-microspheres, and regional water content by drying were then measured. The average T1 of the inner medulla was shorter for the ischemia (1574 msec) than for the contralateral kidney (1849 msec), while no change ws noted in the cortex. Ischemic kidneys had less distinct outer medullary zones on IR images with TI = 600 msec than did contralateral or control kidneys. Blood flow to both the cortex and medulla were markedly reduced in ischemic kidneys compared with contralateral kidneys (119.5 vs. 391 ml/min/100 gm for cortex and 19.8 vs. 50.8 ml/min/100 gm for medulla). Renal water and blood content were less affected. Our rabbit model of renal artery stenosis with MRI, radionuclide, and angiographic correlation has the potential to increase our understanding of MR imaging of the rabbit kidney.

Angiography↗
PubMedDate not supplied

MR imaging of fetal brain.

Magnetic resonance (MR) imaging was used to evaluate normal fetal intracranial anatomy in axial, coronal, and sagittal planes. The T1 and T2 weighted images (WI) of aborted fetuses of varying gestational ages were correlated with anatomic sections. In the premature fetus three distinct intensity zones were seen on MR that were not visualized on gross specimens. Unmyelinated white matter displays low intensity on T1 W1 and high intensity on T2 W1. Maturational changes of the brain were observed with advancing fetal age.

Brain↗
PubMedDate not supplied

Model-driven visualization of coronary arteries.

In a joint project between the Department of Computer and Information Sciences and the Department of Radiology, we are applying techniques of artificial intelligence to improve clinical performance in coronary arteries. Specifically, we are investigating how images from intravenous digital subtraction angiography (DSA) can be enhanced so that their efficacy for lesion detection and quantitation becomes comparable with that of the more dangerous procedure of selective coronary arteriography. The enhancement techniques (which include algorithms for 3-dimensional vessel detection, reconstruction and display, as well as for accurate lumen-size estimation) are based on models of (i) the 3-dimensional topological structure of the coronary arterial tree, (ii) myocardial dynamics, and (iii) the X-ray imaging process involved in producing digital subtraction angiograms. The evaluation of these model-driven visualization techniques is done by the standard psychophysical method of Receiver Operating Characteristic (ROC) analysis applied to observer performance tests on images from an animal coronary atherosclerosis model.

Analog-Digital Conversion↗