Prostate diffusion imaging with distortion correction

Abstract

Purpose Diffusion imaging in the prostate is susceptible to distortion from B0 inhomogeneity. Distortion correction in prostate imaging is not routinely performed, resulting in diffusion images without accurate localization of tumors. We performed and evaluated distortion correction for diffusion imaging in the prostate. Materials and Methods 28 patients underwent pre-operative MRI (T2, Gadolinium perfusion, diffusion at b = 800 s/mm2). The restriction spectrum protocol parameters included b-values of 0, 800, 1500, and 4000 s/mm2 in 30 directions for each nonzero b-value. To correct for distortion, forward and reverse trajectories were collected at b = 0 s/mm2. Distortion maps were generated to reflect the offset of the collected data versus the corrected data. Whole-mount histology, was available for correlation. Results: Across the 27 patients evaluated (excluding one patient due to data collection error), the average root mean square distortion distance of the prostate was 3.1 mm (standard deviation, 2.2 mm; and maximum distortion, 12 mm). Conclusion Improved localization of prostate cancer by MRI will allow better surgical planning, targeted biopsies and image-guided treatment therapies. Distortion distances of up to 12 mm due to standard diffusion imaging may grossly misdirect treatment decisions. Distortion correction for diffusion imaging in the prostate improves tumor localization.

In vivo prostate cancer detection and grading using restriction spectrum imaging-MRI

“…15 RSI-MRI employs spatial distortion correction using opposed phase-encoding polarities, allowing for efficient anatomic localization, an advance that has demonstrated promise for improved preoperative determination of extraprostatic extension of disease. 9,13,15,24 Although not specifically examined in this work, this spatial distortion correction may allow the use of the superior tumor conspicuity available with RSI-MRI for accurate targeted biopsy and/or treatment strategies, and these are currently under investigation by our group.…”

Restriction spectrum imaging improves MRI-based prostate cancer detection

“…The goal is improved conspicuity of highly cellular tumors, which has proven effective in the brain [16–19] and more recently the prostate, though these prior studies were limited by design which involved placement of regions of interest based on knowledge of tumor location [20, 21]. RSI additionally corrects for spatial distortion through acquiring b = 0 images with both forward and reverse phase encoding polarities, and corrects for Eddy currents, allowing for more precise tumor localization and useful in the identification of extraprostatic extension of PCa [20, 22, 23]. …”

Imaging of Local Recurrence in Prostate Cancer

“…Restriction spectrum imaging is a recently devised advanced diffusion technique which models water compartments in tissue by obtaining an extended spectrum of diffusion images -theoretically focusing observed signal from intracellular, restricted water molecules of interest and attenuating signal from other water molecules that typically confound conventional DWI of the prostate [83,84]. Restriction spectrum imaging has demonstrated improved identification of primary PCa in both quantitative and qualitative analyses, and improves localization of disease through distortion correction which often degrades diffusion techniques [85][86][87][88].…”