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

<jats:sec><jats:title>Background</jats:title><jats:p>Decreasing MRI scan time is a key factor to increase patient comfort and compliance as well as the productivity of MRI scanners.</jats:p></jats:sec><jats:sec><jats:title>Purpose/Hypothesis</jats:title><jats:p>Compressed sensing (CS) should significantly accelerate 3D scans. This study evaluated the clinical application and cost effectiveness of accelerated 3D T<jats:sub>2</jats:sub> sequences of the lumbar spine.</jats:p></jats:sec><jats:sec><jats:title>Study Type</jats:title><jats:p>Prospective, cross‐sectional, observational.</jats:p></jats:sec><jats:sec><jats:title>Population</jats:title><jats:p>Twenty healthy volunteers and 10 patients.</jats:p></jats:sec><jats:sec><jats:title>Field Strength/Sequence</jats:title><jats:p>A 3D T<jats:sub>2</jats:sub> 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.</jats:p></jats:sec><jats:sec><jats:title>Assessment</jats:title><jats:p>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.</jats:p></jats:sec><jats:sec><jats:title>Statistical Tests</jats:title><jats:p>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.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>CS with factor 4.5 results in unchanged image quality compared to the T<jats:sub>2</jats:sub> TSE for volunteers and patients (overall image impression: 4.75 vs. 4.20 [<jats:italic>P</jats:italic> = 0.73] and 4.90 vs. 4.47 [<jats:italic>P</jats:italic> = 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 (<jats:italic>P</jats:italic> = 0.89 and <jats:italic>P</jats:italic> = 0.43). A reduction of scan time to 148 seconds (CS 8) was still rated acceptable for most diagnosis.</jats:p></jats:sec><jats:sec><jats:title>Data Conclusion</jats:title><jats:p>CS accelerates the 3D T<jats:sub>2</jats:sub> 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.</jats:p><jats:p><jats:bold>Level of Evidence</jats:bold>: 1</jats:p><jats:p><jats:bold>Technical Efficacy</jats:bold>: Stage 6 J. Magn. Reson. Imaging 2019;49:e164–e175.</jats:p></jats:sec>