Multi‐readout DWI with a reduced FOV for studying the coupling between diffusion and T2* relaxation in the prostate

Abstract

Purpose To develop a DWI sequence with multiple readout echo‐trains in a single shot (multi‐readout DWI) over a reduced FOV, and to demonstrate its ability to achieve high data acquisition efficiency in the study of coupling between diffusion and relaxation in the human prostate. Methods The proposed multi‐readout DWI sequence plays out multiple EPI readout echo‐trains after a Stejskal‐Tanner diffusion preparation module. Each EPI readout echo‐train corresponded to a distinct effective TE. To maintain a high spatial resolution with a relatively short echo‐train for each readout, a 2D RF pulse was used to limit the FOV. Experiments were performed on the prostate of six healthy subjects to acquire a set of images with three b values (0, 500, and 1000 s/mm2) and three TEs (63.0, 78.8, and 94.6 ms), producing three ADC maps at different TEs and three T2*$$ {T}_2^{\ast } $$ maps at different b values. Results Multi‐readout DWI enabled a threefold acceleration without compromising the spatial resolution when compared with a conventional single‐readout sequence. Images with three b values and three TEs were obtained in 3 min 40 s with an adequate SNR (≥ 26.9). The ADC values (1.45 ± 0.13, 1.52 ± 0.14, and 1.58 ± 0.15 μm2false/normalms$$ {\upmu \mathrm{m}}^2/\mathrm{ms} $$; P < 0.01) exhibited an increasing trend as TEs increased (63.0 ms, 78.8 ms, and 94.6 ms), whereas T2*$$ {T}_2^{\ast } $$ values (74.78 ± 13.21, 63.21 ± 7.84, and 56.61 ± 5.05 ms; P < 0.01) decreases as the b values increased (0, 500, and 1000 s/mm2). Conclusion The multi‐readout DWI sequence over a reduced FOV provides a time‐efficient technique to study the coupling between diffusion and relaxation times.