Parallel imaging compressed sensing for accelerated imaging and improved signal-to-noise ratio in MRI-based postimplant dosimetry of prostate brachytherapy

Jeremiah W Sanders; Hao Song; Steven J Frank; Tharakeswara Bathala; Aradhana M Venkatesan; Mitchell Anscher; Chad Tang; Teresa L Bruno; Wei Wei; Jingfei Ma

doi:10.1016/j.brachy.2018.05.003

Parallel imaging compressed sensing for accelerated imaging and improved signal-to-noise ratio in MRI-based postimplant dosimetry of prostate brachytherapy

Brachytherapy. 2018 Sep-Oct;17(5):816-824. doi: 10.1016/j.brachy.2018.05.003. Epub 2018 Jun 4.

Authors

Affiliations

¹ Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: jsanders1@mdanderson.org.
² Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX.
³ Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
⁴ Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX.
⁵ Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX.

PMID: 29880449
DOI: 10.1016/j.brachy.2018.05.003

Abstract

Purpose: To investigate the feasibility of using parallel imaging compressed sensing (PICS) to reduce scan time and improve signal-to-noise ratio (SNR) in MRI-based postimplant dosimetry of prostate brachytherapy.

Methods and materials: Ten patients underwent low-dose-rate prostate brachytherapy with radioactive seeds stranded with positive magnetic resonance-signal seed markers and were scanned on a Siemens 1.5T Aera. MRI comprised a fully balanced steady-state free precession sequence with two 18-channel external pelvic array coils with and without a rigid two-channel endorectal coil. The fully sampled data sets were retrospectively subsampled with increasing acceleration factors and reconstructed with parallel imaging and compressed sensing algorithms. The images were assessed in a blinded reader study by board-certified care providers. Rating scores were compared for statistically significant differences between reconstruction types.

Results: Images reconstructed from subsampling up to an acceleration factor of 4 with PICS demonstrated consistently sufficient quality for dosimetry with no apparent loss of SNR, anatomy depiction, or seed/marker conspicuity when compared to the fully sampled images. Images obtained with acceleration factors of 5 or 6 revealed reduced spatial resolution and seed marker contrast. Nevertheless, the reader study revealed that images obtained with an acceleration factor of up to 5 and reconstructed with PICS were adequate-to-good for postimplant dosimetry.

Conclusions: Combined parallel imaging and compressed sensing can substantially reduce scan time in fully balanced steady-state free precession imaging of the prostate while maintaining adequate-to-good image quality for postimplant dosimetry. The saved scan time can be used for multiple signal averages and improved SNR, potentially obviating the need for an endorectal coil in MRI-based postimplant dosimetry.

Keywords: Compressed sensing; Endorectal coil; MRI; Prostate brachytherapy; SNR.

MeSH terms

Brachytherapy / methods*
Humans
Image Processing, Computer-Assisted / methods*
Magnetic Resonance Imaging / methods*
Male
Prostate / diagnostic imaging*
Prostatic Neoplasms / diagnosis
Prostatic Neoplasms / radiotherapy*
ROC Curve
Radiometry / methods
Retrospective Studies
Signal-To-Noise Ratio