”Radioisotope Arteriography” as an Adjunct to the Brain Scan

Abstract

The brain scan is now widely employed for the evaluation of patients with suspected intracranial lesions. It is a simple, safe, relatively accurate diagnostic procedure and may be used both to screen patients and to complement cerebral arteriography and air studies in the identification of intracranial lesions. Although not as accurate as the latter two procedures in the detection of intracranial pathology (1–3), the brain scan has the decided advantages of lower patient morbidity, better demonstration of the extent of the lesion, availability on an out-patient basis, and a simplicity that makes its repeated use practical in following the course of a disease. In spite of its value, the brain scan has two major disadvantages: (a) it fails to localize all intracranial lesions, particularly those related to occlusive vascular disease, and (b) a positive scan alone is not sufficient to accurately identify the etiology of the lesion (tumor vs. infarction, etc.). The introduction of the scintillation camera has provided a method to visually display in rapid sequential “pictures” the distribution of a radiopharmaceutical within the extracranial and intracranial vascular structures. By this means characterization of the degree of vascularity of intracranial lesions is possible. We have employed the Anger camera (Pho-Gamma III Scintillation Camera) to obtain rapid sequence pictures as an adjunct to the routine brain scan in over 1,000 patients, in an attempt to evaluate this procedure's capability to overcome the two major disadvantages of the brain scan. Materials and Methods “Radioisotope arteriography” was performed on all patients referred to the Nuclear Medicine Laboratory, North Carolina Baptist Hospital, the Bowman Gray School of Medicine, for routine brain scans between November 1967 and September 1968. No preparation of the patient was carried out except in children, who received Lugol's solution prior to the scan to decrease the radiation dose to the thyroid. All procedures were performed with 99mTc pertechnetate obtained from a 99Mo-99mTc generator. The patients were positioned as for an anterior view of the brain with the radioisotope camera (Fig. 1), and a lead apron was draped about the shoulders and chest to diminish scattered radiation from the body. In most instances the standard 1,000-hole 3-inch collimator was employed. The instrument was set for the photo peak of 99mTc and a 15 per cent window was used. Ten to fifteen millicuries of 99mTc pertechnetate was injected intravenously, usually in small volumes (preferably 1–3 ml) of high concentration so that the radiopharmaceutical would arrive in the cerebral circulation as a “bolus.” To minimize dispersion of the bolus, rapid delivery of the solution was achieved by administering it distal to a venous occlusive tourniquet, which was released the moment the injection was completed.