Keywords:
Urinary Tract / Bladder, Genital / Reproductive system male, Abdomen, MR, Diagnostic procedure, Imaging sequences, Cancer
Authors:
R. O'Donohoe, R. Dunne, V. Kimbrell, C. M. Tempany-Afdhal; Boston, MA/US
DOI:
10.1594/ecr2018/C-1171
Aims and objectives
Multiparametric magnetic resonance imaging (mpMRI) of the prostate now plays a central role in the management of prostate cancer. Its use in the local staging of prostate cancer is well established [1,2], and mpMRI can also provide information about tumor aggressiveness [3-5],
allows lesion localization for targeted biopsy [6,7] and can be used as part of an active surveillance program [8].
Additionally,
there is developing evidence that mpMRI can play a role in the initial workup of patients presenting with suspicion of prostate cancer based on the elevation of serum prostate specific antigen (PSA) or findings on digital rectal examination [9].
As prostate mpMRI increases in importance,
so does the need to optimize image acquisition.
Currently,
mpMRI examinations are performed at 1.5T or 3T using a pelvic phased array coil (PPA) with or without the addition of an endorectal coil (ERC) to increase the signal to noise ratio (SNR).
The precise imaging technique used varies across insitutions.
In the Prostate Imaging - Reporting and Data System version 2 (PI-RADS v2) published in 2015,
the authors note that credible imaging results have been obtained without an ERC at 1.5T and 3T,
but the combination of a PPA and ERC increases the SNR at any field strength and with some 1.5T systems the use of an ERC is indispensible [10].
After factoring in issues of time,
cost and patient acceptibility,
there is currently no consensus regarding the optimum imaging technique.
A number of studies have been performed comparing the image quality obtained using different field strengths and coil configurations.
A recent prostate mpMRI study comparing the image quality obtained at 3T using a PPA and a PPA/ERC combination found that T2 weighted (T2w) images were of comparable quality and that diffusion weighted images (DWI) obtained with an ERC demonstrated superior image quality for one of two readers [11].
The same study found a higher SNR for DWI using a PPA over a PPA/ERC combination,
and no significant difference in SNR between the two for T2w.
Another study comparing the diagnostic utility of ERC and non-ERC mpMRI at 3T found ERC examinations to be superior at detecting cancer foci [12].
Since prostate mpMRI involves the acquisition of signal from a small volume of tissue,
positioning the receive coil as near as possible to the gland may be advantageneous.
A new wearable pelvic coil aims to optimize non-ERC mpMRI by positioning the coil elements as close as possible to the perineum and therefore the prostate gland.
By physically wrapping around and conforming to the pelvis,
the coil aims to maximise the signal obtained from the prostate gland.
The purpose of this study is to compare the qualitative and quantitative image quality of T2w and diffusion weighted images acquired using a wearable pelvic coil,
a standard pelvic phased array coil and an endorectal coil.