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

BackgroundDecreasing MRI scan time is a key factor to increase patient comfort and compliance as well as the productivity of MRI scanners. Purpose/HypothesisCompressed sensing (CS) should significantly accelerate 3D scans. This study evaluated the clinical application and cost effectiveness of accelerated 3D T-2 sequences of the lumbar spine. Study TypeProspective, cross-sectional, observational. PopulationTwenty healthy volunteers and 10 patients. Field Strength/SequenceA 3D T-2 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. AssessmentThree 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 TestsAn 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. ResultsCS with factor 4.5 results in unchanged image quality compared to the T-2 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 ConclusionCS accelerates the 3D T-2 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;49:e164-e175.