The Significance of T2-Weighted, Fast-Spin Echo Magnetic Resonance Imaging Scan in a Screening Test for Patients with Acoustic Tumor

Abstract

BACKGROUND AND OBJECTIVES: Although auditory brainstem response(ABR) has been the screening test of choice, recent studies showed that ABR had only a 63% sensitivity and 64% specificity in detecting small acoustic tumor when compared with the magnetic resonance imaging(MRI) scan. Full MRI scans with gadolinium enhancement are highly accurate at detecting these lesions, but these are time consuming and expensive. The purpose of this study is to evaluate the effectiveness of T2-weighted, fast-spin echo(FSE) MRI scan as a screening test for acoustic tumor compared with full MRI scans with gadolinium enhancement. PATIENTS AND METHODS : From January 1995 through March 1999, 293 patients visiting to Department of otolaryngology underwent full MRI scans with gadolinium enhancement including T2-weighted FSE MRI to rule out the acoustic tumor. Pure tone audiogram was routinely performed in all the patients. One hundred fifty four of these patients received speech audiogram. Decreased speech discrimination score below 60% was considered abnormal. ABR was ordered to 65 patients. Interaural latency difference for wave V greater han 0.2 msec was considered abnormal. RESULTS: Eleven of 293 cases were detected as acoustic tumor on T2-weighted FSE MRI scan and gadolinium-enhanced MRI scan. The tumors less than 1.5 cm in diameter were 7 cases, and 3 cases of normal ABR was all less than 1 cm in diameter. T2-weighted FSE MRI scan had 100% sensitivity and 99.6% specificity, while ABR showed relatively low sensitivity(72.7%) and specificity(33.3%). CONCLUSION: T2-weighted FSE MRI scan is so sensitive to acoustic tumor that is comparable to full MRI scans with gadolinium enhancement. And it has rapid performance time and low cost. However, ABR has low sensitivity for acoustic tumor, especially for small tumor less than 1 cm in diameter. So, T2-weighted FSE MRI scan is considered as a cost-effective screening test for early detection of acoustic tumor.