Segmented diffusion-weighted imaging of the prostate: Application to transperineal in-bore 3T MR image-guided targeted biopsy

Abstract

Objective-To evaluate the applicability of using single-shot and multi-shot segmented diffusion-weighted imaging (DWI) techniques to support biopsy target localization in a cohort of targeted MRI-guided prostate biopsy patients.Materials and Methods-Single-shot echo-planar diffusion-weighted imaging (SS-DWI) and multi-shot segmented (MS-DWI) were performed intra-procedurally on a 3 Tesla system in a total of 35 men, who underwent in-bore prostate biopsy inside the scanner bore. Comparisons between SS-DWI and MS-DWI were performed with (in 16 men) and without (in 19 men) parallel coil acceleration (iPAT) for SS-DWI. Overall image quality and artifacts were scored by a radiologist and scores were compared with the Wilcoxon Mann-Whitney rank test. Correlation between the presence of air and image quality scores was evaluated with Spearman statistics. To quantify distortion, the anteroposterior prostate dimension was measured in SS and MS b=0 diffusion-and T 2 -weighted images. Signal-to-noise ratio was estimated in a phantom experiment. Agreement and accuracy of targeting based on retrospective localization of restricted diffusion areas in DWI was evaluated with respect to the targets identified using multiparametric MRI (mpMRI).Results-Compared to SS-DWI without iPAT, the average image quality score in MS-DWI improved from 2.0 to 3.3 (p<0.005) and the artifact score improved from 2.3 to 1.4 (p<0.005). When iPAT was used in SS-DWI, the average image quality score in MS-DWI improved from 2.6 to 3.3 (p<0.05) and the artifact score improved from 2.1 to 1.4 (p<0.01). Image quality (ρ=−0.74, p<0.0005) and artifact scores (ρ=0.77, p<0.0005) both showed strong correlation with the presence of air in the rectum for the SS-DWI sequence without iPAT. These correlations remained Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript significant when iPAT was enabled (ρ=−0.52, p<0.05 and ρ=0.64, p<0.01). For the comparison MS-DWI vs SS-DWI without iPAT, median differences between diffusion-and T 2 -weighted image gland measurements were 1.1 (0.03-10.4) mm and 4.4 (0.5-22.7) mm, respectively. In the SS-DWI-iPAT cohort, median gland dimension differences were 2.7 (0.4-5.9) mm and 4.2 (0.7-8.9) mm, respectively. Out of the total of 89 targets identified in mpMRI, 20 had corresponding restricted diffusion areas in SS-DWI and 28 in MS-DWI. No statistically significant difference was observed between the distances for the targets in the target-concordant SS-and MS-DWI restricted diffusion areas (5.5 mm in SS-DWI...

Quantitative diffusion MRI using reduced field-of-view and multi-shot acquisition techniques: Validation in phantoms and prostate imaging

“…From our results, quantitative diffusion measurements obtained from recently developed reduced-distortion pulse sequences (rFOV and msEPI) were in good agreement with the standard ssEPI-based measurements. In combination with the reduced distortion provided by these novel pulse sequences (as has been demonstrated in previous works [18–20, 35–39] as well as in this study), these results demonstrate the potential of rFOV and msEPI, at the cost of FOV size or scan time, to provide reproducible quantitative diffusion measurements compared to ssEPI. This potential may have significant research and clinical implications for diffusion MRI of the prostate.…”

“…Importantly, both rFOV and msEPI enable DWI imaging with higher resolution and higher overall image quality including greater resolvable spatial resolution and reduced distortions [14, 17]. In recent studies, both rFOV and msEPI have been shown to provide improved diffusion-weighted image quality for prostate cancer detection compared to conventional ssEPI [18–20, 35–39].…”

Implementing diffusion-weighted MRI for body imaging in prospective multicentre trials: current considerations and future perspectives

“…Cardiac triggering has been explored in the upper abdomen [ 24 ]. Anti-peristaltic agents reduce image blur arising from peristaltic motion in abdominal and pelvic DW-MRI and multishot techniques may offer some advantages over single-shot techniques in reducing distortion from air within bowel [ 25 ].

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Accelerated Segmented Diffusion-Weighted Prostate Imaging for Higher Resolution, Higher Geometric Fidelity, and Multi-b Perfusion Estimation

“…Diffusion images provide the most critical information for cancer diagnosis in a multiparametric prostate exam, yet conventional diffusion image quality in comparison to typical T 1 and T 2 -weighted images is clearly inferior. Therefore, perfecting geometric fidelity and spatial resolution of the diffusion scan promises to be of great diagnostic value, but also very desirable for more accurate biopsy and intervention guidance (15,36). The present study demonstrates that a segmented acquisition can improve geometric fidelity and at the same time enhance spatial resolution of the diffusion imaging sequence in a multiparametric prostate exam.…”

“…With multi-coil acquisitions, parallel imaging is typically the first choice to reduce distortion artifacts (8). For greater reductions, parallel imaging can be combined with the reversed gradient method (9,10), or with segmentation along either the readout (11,12) or phase encode (13) direction, and such combinations of methods have been applied to prostate diffusion imaging (14)(15)(16)(17). An increase by a few-fold in scan time and the need for correction of motion-related phase errors are the primary downsides of segmented diffusion imaging.…”