Biomedical subjects

B J Soher

Publications and source records attributed to B J Soher.

21 records · Page 2Linked to original sources

PubMed1993

Quantitative proton spectroscopy and histology of a canine brain tumor model.

Quantitative, single voxel proton nuclear magnetic resonance (NMR) spectroscopy and histological analysis was performed in eight dogs implanted with the transplantable canine glioma model of Wodinsky (Proc. Am. Assoc. Cancer Res. 10, 99 (1969)). Signals from choline, creatine, N-Acetyl Aspartate (NAA) and lactate were converted to molar concentration units and correlated with the quantitative analysis of histologically determined tissue types within the localized volume selected for NMR spectroscopy. In general, compared with normal brain, the lesions were associated with reductions in all metabolite concentrations, with the exception of lactate, which was increased. NAA and creatine decreases were most significantly correlated with the total lesion volume (P < 0.01), suggesting that these compounds are present in normal brain only. Changes in choline levels did not correlate strongly with any particular tissue type. Lactate was found to increase with increasing total lesion volume (P < 0.01), but not with increasing percent tumor, suggesting that it accumulates in abnormal tissue other than the tumor. The spectra reported were similar to those observed in human glioblastomas, with the exception that elevations of choline were not observed. The transplantable canine gliosarcoma system appears to be a suitable tumor model for evaluation by clinical radiological techniques such as magnetic resonance imaging (MRI) and proton NMR spectroscopy.

Animals↗

PubMedDate not supplied

Quantitation of proton NMR spectra of the human brain using tissue water as an internal concentration reference.

The use of cerebral water as an internal intensity standard for the quantitation of spatially localized proton spectra of the human brain is investigated. The method is validated on standard samples of N-acetyl aspartate (NAA) and lactate, and possible sources of error are discussed. Using the STEAM pulse sequence, concentrations of choline, creatine and NAA in frontal lobe white matter are found to be 1.9 +/- 0.5, 10.6 +/- 1.3 and 16.6 +/- 2.3 mumol/g wet wt, respectively, in 10 normal volunteers. In the thalamus, the concentrations are 2.0 +/- 0.4, 11.6 +/- 2.0 and 17.2 +/- 1.3 mumol/g wet wt, respectively. Choline and creatine concentrations are in good agreement with conventional biochemical values: NAA concentrations are found to be three-fold higher, suggesting overlap of the NAA signal with other compounds. Quantitation relative to tissue water is a convenient and rapid means of quantitating proton spectra of the human brain.

Adult↗

PubMedDate not supplied

Comparison of functional MR and H2 15O positron emission tomography in stimulation of the primary visual cortex.

PURPOSE: To locate spoiled gradient-echo functional MR signal changes in relation to brain parenchyma. METHODS: The region of the primary visual cortex was evaluated using functional MR and H2 15O positron emission tomography in each of six male subjects who were being visually stimulated by means of red light-emitting diode flash goggles. RESULTS: The positron emission tomography technique demonstrated substantially greater relative signal change with visual stimulation than did the functional MR technique. Furthermore, the functional MR signal changes were concentrated in loci around the periphery of brain parenchyma exhibiting increased radiotracer activity, as opposed to being collocated. CONCLUSIONS: Signal changes found using functional MR based on gradient-echo techniques reflect primarily phenomena occurring within small veins and underrepresent activity intrinsic to brain parenchyma, thus introducing potential inaccuracies in locating regions of activated brain tissue. Positron emission tomography, however, directly measures changes in metabolically related activity within the parenchyma.

Adult↗