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A new template technique has been developed for implanting hyperthermia catheters in the treatment of brain tumors. The technique utilizes an imaging template and a drill template which can be rigidly secured to the head with three skull screws. The anatomic and vascular information needed for hyperthermia treatment planning may be assessed with three-dimensional magnetic resonance (MR) imaging and angiography acquisitions which use a surface coil. In the companioning treatment planning system the catheter positions and lengths and the electrodes in the catheter can be interactively manipulated relative to the anatomy and vasculature. The visualization of the blood vessels relative to the template allows the minimization of the risk on intracranial hemorrhages. This template technique is useful for any brain tumor implants, especially when a large number of catheters are involved. A phantom test has shown that this procedure has an accuracy in the order of 1 mm provided that the MR-related geometry distortions are minimized. Index Terms - Brain implants, implantation template, interstitial hyperthermia, treatment planning.

Even a temporary disruption in the blood supply to an area of the brain may result in irreversible damage. An area of such damage, an infarction, is often visible on imaging with CT scan or magnetic resonance imaging (MRI). In some patients, an infarction may result in the clinical symptoms of stroke. The accumulation of several infarctions may cause dementia, a condition called multi-infarct dementia. Hypertension is a very important risk factor for both stroke and multi-infarct dementia. However, not all patients with both hypertension and dementia have infarcts that are visible on CT scan. In such cases, the dementia may be associated with diffuse abnormalities spread through the white matter of the brain, rather than associated with distinct areas of infarction. MRI has revealed that diffuse white matter lesions are not uncommon among elderly subjects. A study was conducted to evaluate the relationship between these white matter lesions, high blood pressure, and cognitive impairment. The subjects were 42 elderly patients with hypertension; the average age of these patients was 66.2 years. Observations made on these patients were compared with those made on a control group of 42 subjects matched for age but without high blood pressure. White matter lesions were seen in 10 of the hypertensive subjects, but in only one control subject. The white matter lesions were more likely to be found among the older patients, but were apparently unrelated to the number of years that the patient had suffered from hypertension. Thirty-four of the hypertensive patients and 18 of the control subjects were given extensive evaluations of intellectual performance. These tests revealed that the patients with the white matter lesions visible on MRI were significantly impaired compared with the subjects without these lesions. However, when the hypertensive subjects without white matter lesions were compared with normal subjects without lesions, there were no significant differences in the cognitive performance. The results suggest that hypertension, a known risk factor for stroke and multi-infarct dementia, also increases the risk of diffuse white matter damage. This diffuse white matter damage contributes to the decline in intellectual performance among some elderly patients. (Consumer Summary produced by Reliance Medical Information, Inc.)