Dynamic contrast-enhanced MRI of the prostate with high spatiotemporal resolution using compressed sensing, parallel imaging, and continuous golden-angle radial sampling: Preliminary experience

Abstract

Purpose To demonstrate dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate with both high spatial and temporal resolution via a combination of golden-angle radial k-space sampling, compressed sensing, and parallel-imaging reconstruction (GRASP), and to compare image quality and lesion depiction between GRASP and conventional DCE in prostate cancer patients. Materials and Methods Twenty prostate cancer patients underwent two 3T prostate MRI examinations on separate dates, one using standard DCE (spatial resolution 3.0 × 1.9 × 1.9 mm, temporal resolution 5.5 sec) and the other using GRASP (spatial resolution 3.0 × 1.1 × 1.1 mm, temporal resolution 2.3 sec). Two radiologists assessed measures of image quality and dominant lesion size. The experienced reader recorded differences in contrast arrival times between the dominant lesion and benign prostate. Results Compared with standard DCE, GRASP demonstrated significantly better clarity of the capsule, peripheral/ transition zone boundary, urethra, and periprostatic vessels; image sharpness; and lesion conspicuity for both readers (P<0.001–0.020). GRASP showed improved interreader correlation for lesion size (GRASP: r=0.691–0.824, standard: r=0.495–0.542). In 8/20 cases, only GRASP showed earlier contrast arrival in tumor than benign; in no case did only standard DCE show earlier contrast arrival in tumor. Conclusion High spatiotemporal resolution prostate DCE is possible with GRASP, which has the potential to improve image quality and lesion depiction as compared with standard DCE.

Compressed sensing MRI: a review of the clinical literature

“…1,2,18,21,22,25,28,29 All of these studies found that the combined methodology produced images deemed acceptable or not significantly different from fully sampled images, while employing acceleration rates from 23 to 7.23, depending on the application. Five of these studies compared the combined method with the standard imaging protocol for the respective study's imaging application.…”

“…32 A total of 275 subjects were imaged across the 18 studies (range, 3-34; mean 5 15.28; median 5 11.5; standard deviation 5 10.23). 7 studies imaged healthy subjects, 15,[19][20][21]23,24,27 and 11 imaged patients referred for the type of imaging under consideration 1,2,14,[16][17][18]22,25,26,28,29 ( Figure 5). …”

“…22 In 10 studies human readers rated images. 1,15,18,[21][22][23][26][27][28][29] In eight studies, accurate measurement of a quantitative metric with CS MRI (e.g. contrast uptake or metabolite concentration) was assessed.…”

“…27 All eight studies that tested acceleration factors up to 23 reported diagnostically acceptable images or images not significantly different from gold standard images at a given degree of undersampling. [15][16][17]19,20,23,26,28 In only two of these studies was acceleration also successfully pushed beyond 23. 15,17 Of the 27 tests of acceleration factors .2, 18 tests were successful while 9 failed to produce acceptable images.…”

Practical aspects of prostate MRI: hardware and software considerations, protocols, and patient preparation

“…Compressed sensing techniques have been implemented into DCE sequences to improve spatiotemporal resolution or increase the coverage. Recently, Rosenkrantz et al reported the use of a highspatiotemporal resolution DCE technique GRASP (Golden-angle Radial Sparse Parallel), which allows for image acquisition with spatial resolution of 1.1 9 1.1 9 3.0 mm and temporal resolution of 2.3 s [102].…”