[Clinical evaluation of brain scintigrams for basal midline lesions (author's transl)]

Brain scintigrams with 8-10 mci of pertechnetate were studied refering to surgical, histological and other neuroradiological findings in 91 cases with diagnosis or suspect of basal midline lesions. Anterior view of 45 cases was stored in high speed magnetic tape, displayed on CRT of our data processing system and studied of the ratio of average count for regions of interest, 2 cm x 2 cm in size, placed on the areas of lesion, the sagittal sinus and the normal brain hemispheres. In 18 pituitary adenomas, excluding acromegaly and other intrasellar lesions, 89% of cases with surgical indication for optic nerve symptoms were reported as abnormal scintigrams. In 20 craniopharyngiomas, 11 positive cases consisted mainly of solid, recurrent or thick cystic tumors. Five of 6 ectopic pinealomas and all 6 parasellar or medial sphenoidal ridge meningiomas showed positive uptake. Average counts of the regions of interest placed on tumor areas were 169.4% of normal hemispheric areas in 9 pituitary adenomas, 192.5% in 3 solid craniopharyngiomas, 192.3% in 6 meningiomas and 193.3% in ectopic pinealomas. The difference in the average ratio of the lesion count to the normal hemispheric count was statistically significant between cystic craniopharyngioma and adenoma, ectopic pinealoma, meningioma, glioma and solid craniopharyngioma, and between adenoma and acromegaly with p less than 0.005, and between solid craniopharyngioma and acromegaly, and between glioma and acromegaly with p less than 0.025. In the ratio of the lesion count to the sagittal sinus count, on the other hand, the difference of the average ratio was significant with p less than 0.005, only between cystic craniopharyngioma and ectopic pinealoma, and between cystic and solid craniopharyngioma. These facts suggested that the sagittal sinus count was unsuitable to be the standard count of an anterior scintigram to compare with basal midline count. The routine Polaroid scintigram with Tc99m pertechnetate proved their useful clinical diagnostic value for various basal midline lesions, the size of which indicated the surgical procedures. The digital analysis of anterior scintigrams supported the clinical value of the routine brain scintigram in the detection of these lesions. The ratio of the average count of the basal midline lesion to the normal brain area on the anterior scintigram presents more useful clinical information than the ratio of the lesion to the sagittal sinus count. Brain scintigram is found to be very helpful for the differential diagnosis between solid and cystic sellar tumors which is very important for the decision of surgical indications, and is not always possible by any other conventional neuroradiological procedures.