ARTERIOVENOUS SHUNT MEASUREMENT DURING ENDOVASCULAR THERAPY FOR CEREBROSPINAL LESIONS

PURPOSE: To determine (a) whether superselective angioscintigraphy wit h technetium-99m macroaggregated albumin (Tc-99m-MAA) can be used for the evaluation of arteriovenous shunting in tumors and vascular malfor mations of the head and spine and (b) whether the amount of microparti cles shunted is related to diagnosis, lesion size, or angiographic pat tern. METHODS: Particles of Tc-99m-MAA with a calibrated diameter of 2 5 to 50 mu m were delivered intraarterially in feeders of head and spi ne tumors and vascular malformations in 38 patients, The first estimat ion of the proportion of particles reaching the lungs was made on-line in the angiography suite using a hand-held lead-shielded detector, Ev aluation of the intralesional shunt (pulmonary shunt index, or PSI) wa s derived from quantitative gamma camera recordings of tumoral and pul monary activity after the embolization procedure was complete. RESULTS : The PSI value ranged from 48% to 100% for vascular malformations and vascular tumors (n = 11), 82% to 95% for juvenile angiofibromas (n = 4), 63% to 70% for high-grade gliomas (n = 2), 0% to 50% for renal cel l carcinoma metastases (n = 4), 0% to 86% for meningiomas (n = 11), an d 0% to 36% for paragangliomas (n = 6), Angiographically, the presence of visible arteriovenous channels was predictive of a high PSI. In co ntrast, the presence of early venous drainage was associated with a wi de PSI range, CONCLUSION: Superselective Tc-99m-MAA angioscintigraphy of tumors and vascular malformations of the head and spine is a valuab le method for quantifying an intralesional arteriovenous shunt before embolization.