USE OF INTRAOPERATIVE ULTRASOUND FOR LOCALIZING TUMORS AND DETERMINING THE EXTENT OF RESECTION - A COMPARATIVE-STUDY WITH MAGNETIC-RESONANCE-IMAGING

A prospective study of 70 patients with intraparenchymal brain lesions (36 gliomas and 34 metastases) was performed to evaluate the efficacy of intraoperative ultrasound (IOUS) in localizing and defining the bo rders of tumors and in assessing the extent of their resection. Eighte en of the 36 glioma patients had no previous therapy. All of these 18 tumors were well localized by IOUS; margins were well defined in 15 an d moderately defined in three. The extent of resection was well define d on IOUS In all 18 patients, as confirmed by measurements taken on po stoperative magnetic resonance (MR) images (p = 0.90). The remaining 1 8 patients with gliomas had undergone previous surgery and/or radiatio n therapy; five had recurrent tumors and 13 had radiation-induced chan ges. The extent of resection of the recurrent tumors was well defined in all but one patient, as confirmed by postoperative MR imaging. The extent of resection was poorly defined in all 13 patients whose pathol ogy showed radiation effects. All 34 metastatic lesions were well loca lized and had well-defined margins. In addition, IOUS accurately deter mined the extent of resection in all cases; the results were confirmed with postoperative MR imaging. In conclusion, IOUS is not only helpfu l in localizing and defining the margins of gliomas and metastatic bra in lesions, it also accurately determines the extent of resection, as confirmed by postoperative MR imaging. This assessment does not apply, however, when the lesion is due primarily to radiation effect.