Two-centre comparative experimental study of biparametric MRI at 3.0 T with and without endorectal coil using kiwifruit (Actinidia deliciosa) as a phantom for human prostate

Abstract

Background Application of an endorectal coil (ERC) for 3.0-T prostate magnetic resonance imaging (MRI) is contentious. We hypothesised that a multicoil phased-array protocol provides T2-weighted images (T2WI) and diffusion-weighted images (DWI) with reduced field-of-view (DWI reduced ) and monoexponential apparent diffusion coefficient (ADC) maps that are technically equivalent with ERC or without ERC (noERC). Methods Axial T2WI (repetition time [TR] 7500 ms, echo time [TE] 98–101 ms) and DWI reduced (field-of-view 149–179 × 71–73 mm 2 , TR/TE 4500–5500/61–74 ms, b values, 50/800 s/mm 2 ) ERC and noERC images were obtained on identical clinical 3.0-T scanners at two centres and compared for signal-to-noise ratio (SNR) in anterior and posterior outer pericarp (OP) and peripheral placenta (PP) in five green Hayward kiwifruit ( Actinidia delicios a, European Union regulation 543/2011 class 2). Corroboration in 21 patients with benign prostate hyperplasia (negative biopsy, prostate imaging reporting and data system version 2 ≤ 2) involved identical MRI protocols: 10 at site 1, noERC, and 11 at site 2, with ERC. Two-tailed Student’s t test was used. Results With few exceptions, signal-to-noise ratio (SNR) was similar in kiwifruits and prostates for ERC and noERC. In T2WI, SNR was higher posteriorly in noERC MRI for peripheral zone (PZ) ( p < 0.001). In DWI reduced , SNR was higher posteriorly in ERC-OP ( p = 0.013) and ERC-PZ ( p = 0.026) for b = 50 s/mm 2 ; noERC-OP ( p = 0.044) and ERC-PZ ( p = 0.001) for b = 800 s/mm 2 ; and ERC-OP ( p = 0.001), noERC-OP ( p = 0.001), and ERC-PZ ( p = 0.001) for ADC, respectively. Volumes of kiwifruits and prostates were similar (89.2 ± 11.2 versus 90.8 ± 48.5 cm 3 , p = 0.638–0.920). Conclusions Findings imply that multicoil phased-array 3.0-T prostate MRI with T2WI and DWI reduced with ADC maps provides equivalent results with and without ERC.

Quality Comparison of 3 Tesla multiparametric MRI of the prostate using a flexible surface receiver coil versus conventional surface coil plus endorectal coil setup

“…These observations have been confirmed by several published studies [9,10,13]. Different correction algorithms have been developed to compensate signal inhomogeneity, but these may lead to noise level variation and an increase of acquisition time [11,12,29]. It has to be considered that rectal gas if present may lead to similar susceptibility artifacts as gas in ERC.…”

“…ERCs were previously considered indispensable when patients were scanned using 1.5 T MR scanners. However, several recent studies revealed comparable image quality and similar prostate cancer detection rates with or without ERCs using modern 3 T MR scanners and surface pelvic phased-array receiver coils [10,[12][13][14][15][16][17]. One potential limitation of prior studies is that all radiologists comparing the different coil setups came from the same or closely connected institutions, which may have influenced their quality assessment in favor of the routinely utilized technique in these institutions [9,10,13].…”