Accelerated Imaging of the Lumbar Spine: Compressed Sensing for the Clinical Routine

Introduction: Reducing scan time is a key factor to increase patient comfort and the cost effectiveness of magnetic resonance imaging (MRI) scanners. Despite the widespread implementation of parallel imaging techniques, sagittal scans with no or only minor acceleration factors have widely remained the standard in clinical routine, mostly due to the susceptibility to artifacts. Compressed sensing offers a new way to accelerate MRI scans by random undersampling.

Material and Methods: Ten volunteers received a sagittal T2 turbo spin-echo (TSE) scan of the lumbar spine. The scans were performed with five different acceleration factors of compressed sensing, three factors of sensitivity encoding (SENSE), and without any acceleration. Additional reconstructions with a TSE-based prescan and autocalibration were used for further artifact reduction. Two readers independently reviewed the images and scored the delineation of anatomical structures and diagnostic quality on a 5-point scale.

Results: The application of compressed sensing and TSE-based prescans can reduce the scan time of a sagittal T2 sequence by 62%, or 118 s, with unchanged and excellent diagnostic certainty. Reducing the scan time to 28% of the original time still results in good visibility. TSE prescans led to better overall image quality than the standard prescan or autocalibration.

Conclusion: Compressed sensing in combination with TSE prescans offers significant scan time reduction in the clinical routine with unchanged image quality. This increases the cost effectiveness of existing MRI scanners and helps cope with the increasing demand for MRI scans.