Compressed-sensing multispectral imaging of the postoperative spine.
OBJECTIVE
To apply compressed sensing (CS) to in vivo multispectral imaging (MSI), which uses additional encoding to avoid magnetic resonance imaging (MRI) artifacts near metal, and demonstrate the feasibility of CS-MSI in postoperative spinal imaging.


METHODS
Thirteen subjects referred for spinal MRI were examined using T2-weighted MSI. A CS undersampling factor was first determined using a structural similarity index as a metric for image quality. Next, these fully sampled datasets were retrospectively undersampled using a variable-density random sampling scheme and reconstructed using an iterative soft-thresholding method. The fully and undersampled images were compared using a 5-point scale. Prospectively undersampled CS-MSI data were also acquired from two subjects to ensure that the prospective random sampling did not affect the image quality.


RESULTS
A two-fold outer reduction factor was deemed feasible for the spinal datasets. CS-MSI images were shown to be equivalent or better than the original MSI images in all categories: nerve visualization: P = 0.00018; image artifact: P = 0.00031; image quality: P = 0.0030. No alteration of image quality and T2 contrast was observed from prospectively undersampled CS-MSI.


CONCLUSIONS
This study shows that the inherently sparse nature of MSI data allows modest undersampling followed by CS reconstruction with no loss of diagnostic quality.
Department of Radiology, Stanford University, Stanford, California, USA. worters@stanford.edu
Pauline W
PW
Worters
Kyunghyun
K
Sung
Kathryn J
KJ
Stevens
Kevin M
KM
Koch
Brian A
BA
Hargreaves
D000465:Algorithms; D016477:Artifacts; D044962:Data Compression / Q000379:methods; D003952:Diagnostic Imaging / Q000379:methods*; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015233:Models, Statistical; D016011:Normal Distribution; D011184:Postoperative Period; D012189:Retrospective Studies; D013131:Spine / Q000473:pathology*