Accelerated MRI of the Lumbar Spine Using Compressed Sensing: Quality and Efficiency.

ABSTRACT

BACKGROUND: Decreasing MRI scan time is a key factor to increase patient comfort and compliance as well as the productivity of MRI scanners. PURPOSE/HYPOTHESIS: Compressed sensing (CS) should significantly accelerate 3D scans. This study evaluated the clinical application and cost effectiveness of accelerated 3D T2 sequences of the lumbar spine. STUDY TYPE Prospective, cross-sectional, observational. POPULATION Twenty healthy volunteers and 10 patients. FIELD STRENGTH/SEQUENCE A 3D T2 TSE sequence, identical 3D sequences with three different parallel imaging and CS accelerating factors, and 2D TSE sequences as a clinical reference were obtained on a 3T scanner. ASSESSMENT Three readers evaluated the sequences for delineation of anatomical structures and image quality. A quantitative analysis consisting of root mean square error, structural similarity index, signal-to-noise ratio, and contrast-to-noise ratio were performed. The scan times were used to calculate cost differences for each sequence. STATISTICAL TESTS An analysis of variance with repeated measurements and the Friedman test were used to test for potential differences between the sequences. Post-hoc analysis was made with the chi-squared and Tukey-Kramer test. RESULTS: CS with factor 4.5 results in unchanged image quality compared to the T2 TSE for volunteers and patients (overall image impression 4.75 vs. 4.20 [P = 0.73] and 4.90 vs. 4.47 [P = 0.44]). The CS 4.5 scan is 167 seconds (-39%) faster than the 3D and 216.5 seconds (-45%) faster than the 2D sequences. No significant differences was found for the diagnostic certainty in the volunteers and patients between 2D TSE and 3D CS 4.5 (P = 0.89 and P = 0.43). A reduction of scan time to 148 seconds (CS 8) was still rated acceptable for most diagnosis. DATA CONCLUSION: CS accelerates the 3D T2 without compromising image quality. The 3D sequences offer comparable diagnostic quality to the clinical 2D standard with less scan time (-45%), potentially increasing the productivity of MRI scanners. LEVEL OF EVIDENCE 1 Technical Efficacy Stage 6 J. Magn. Reson. Imaging 2019;49e164-e175.