Accelerated Internal Auditory Canal Screening Magnetic Resonance Imaging Protocol With Compressed Sensing 3-Dimensional T2-Weighted Sequence.

Abstract

High-resolution T2-weighted sequences are frequently used in magnetic resonance imaging (MRI) studies to assess the cerebellopontine angle and internal auditory canal (IAC) in sensorineural hearing loss patients but have low yield and lengthened examinations. Because image content in the Wavelet domain is sparse, compressed sensing (CS) that uses incoherent undersampling of k-space and iterative reconstruction can accelerate MRI acquisitions. We hypothesized that an accelerated CS T2 Sampling Perfection with Application optimized Contrasts using different flip angle Evolution (SPACE) sequence would produce acceptable diagnostic quality for IAC screening protocols. Seventy-six patients underwent 3 T MRI using conventional SPACE and a CS T2 SPACE prototype sequence for screening the IACs were identified retrospectively. Unilateral reconstructions for each sequence were separated, then placed into mixed folders for independent, blinded review by 3 neuroradiologists during 2 sessions 4 weeks apart. Radiologists reported if a lesion was present. Motion and visualization of specific structures were rated using ordinal scales. McNemar, Wilcoxon, Cohen κ, and Mann-Whitney U tests were performed for accuracy, equivalence, and interrater and intrarater reliability. T2 SPACE using CS reconstruction reduced scan time by 80% to 50 seconds and provided 98.7% accuracy for IAC mass detection by 3 raters. Radiologists preferred conventional images (0.7-1.0 reduction on 5-point scale, P < 0.001), but rated CS SPACE acceptable. The 95% confidence for reduction in any cerebellopontine angle, IAC, or fluid-filled inner ear structure assessment with CS SPACE did not exceed 0.5. Internal auditory canal screening MRI protocols can be performed using a 5-fold accelerated T2 SPACE sequence with compressed sensing while preserving diagnostic image quality and acceptable lesion detection rate.