Transcranial sonography of brain tumors in the adult: An in vitro and in vivo study

Background. Few reports indicate the potential of transcranial sonography ( TCS) in detecting human brain tumors. Methods. With an Agilent Sonos 2500 u ltrasound device, the authors studied 4 brain tumor phantoms and compared t he findings with magnetic resonance imaging (MRI). TCS was performed on 40 patients with intracranial tumors in a follow-up design. Sonographic tumor volume and affection of the ventricular system were compared with MRI findi ngs. Results. The authors found a good correlation between TCS and MRI volu metry in the in vitro study. TCS showed good intraobserver and interobserve r reliability. A new volumetric formula for TCS measurement was determined. TCS detection rate of brain tumors in vivo was 40%. When the investigators were given access to radiological findings, the rate of tumor identificati on was 80%. Despite a sufficient acoustic window, 40% of gliomas grade II a nd III were not detected. One glioblastoma was not identified owing to an i nsufficient temporal acoustic window. Tumor volumes measured with MRI and T CS correlated well. MRI volumes exceeded TCS volumes by 41%. In the postope rative examinations (mean = 8 days postoperative, n = 15), the resection ca vity was displayed as hyperechogenic. It appeared impossible to differentia te between residual tumor tissue and normal repair mechanisms or blood. In the follow-up examination (mean = 99 days postoperative, n = 15)in 5 patien ts, neither MRI nor TCS showed tumor regrowth. Ten patients had residual tu mors that were detected by sonography. Conclusions. The value of TCS for th e diagnostics of brain tumors is at present limited. Once the tumor has bee n identified, sonographic results match well with those of MRI.