No abstract

This study sought to correlate quantitative presurgical proton magnetic resonance spectroscopic imaging (1H-MRSI) and diffusion imaging (DI) results with quantitative histopathological features of resected glioma tissue. The primary hypotheses were (1) glioma choline signal correlates with cell density, (2) glioma apparent diffusion coefficient (ADC) correlates inversely with cell density, (3) glioma choline signal correlates with cell proliferative index. Eighteen adult glioma patients were preoperatively imaged with 1H-MRSI and DI as part of clinically-indicated MRI evaluations. Cell density and proliferative index readings were made on surgical specimens obtained at surgery performed within 12 days of the radiologic scans. The resected tissue location was identified by comparing preoperative and postoperative MRI. The tumor to contralateral normalized choline signal ratio (nCho) and the ADC from resected tumor regions were measured from the preoperative imaging data. Counts of nuclei per high power field in 5-10 fields provided a quantitative measure of cell density. MIB-1 immunohistochemistry provided an index of the proportion of proliferating cells. There was a statistically significant inverse linear correlation between glioma ADC and cell density. There was also a statistically significant linear correlation between the glioma nCho and the cell density. The nCho measure did not significantly correlate with proliferative index. The results indicate that both ADC and spectroscopic choline measures are related to glioma cell density. Therefore they may prove useful for differentiating dense cellular neoplastic lesions from those that contain large proportions of acellular necrotic space.

Full neurosurgical procedures may be performed in the weak fringe fields surrounding an MRI system, using standard operating room equipment. This approach to iMR-guided neurosurgery offers a significant cost advantage over retrofitting an entire operative suite with "MRI-compatible" surgical equipment. The surgeon's familiarity with standard equipment and the reliability of the equipment are additional advantages. Neurosurgery in the fringe fields allows the neurosurgeon to utilize serial MRI with a minimum of inconvenience, disruption, and change to the standard neurosurgical procedure. Serial intraoperative imaging to visualize the changes in the brain that are associated with neurosurgical intervention seems to enhance the ability to safely and effectively accomplish neurosurgical goals.

Our study describes the anatomy of the middle cerebral artery (MCA) in 65 Sprague-Dawley rats and the spatial distribution of ischemic cortical lesions caused by occluding major MCA branches. The rats characteristically had at least two major MCA branches, frontal and parietal. Many rats had additional branches supplying the pyriform and temporal cortexes. Permanent occlusion of the frontal or parietal branches combined with 30 minutes of bilateral carotid artery occlusion produced visible Evans blue dye uptake by ischemic cortical areas after 24 hours. No lesions distal to the occlusion were apparent in 38% and 43% of rats with frontal and parietal branch occlusions, respectively; small lesions contiguous with the occlusion site were observed in 38% and 32% of the rats. Only 6% of the frontal and 7% of the parietal branch occlusions produced isolated distal infarcts as expected if these branches were end-arteries. Blood flow was reversed in arteries distal to the occlusion. We conclude that extensive collateral connections of the frontal and parietal MCA branches with other arterial systems protect the anterior and posterior cortical regions. In contrast, occlusions of the pyriform branch of the MCA invariably caused infarcts in the frontopyriform region. In about one third of the rats, frontal or parietal branch occlusions produced lesions involving much of the proximal MCA territory; the frontopyriform region was most consistently affected. Combined, these data suggest that the pyriform MCA branch is an end-artery and that the cortical region it supplies is prone to ischemic damage resulting from any reduction of blood flow through the main MCA trunk.(ABSTRACT TRUNCATED AT 250 WORDS)