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Improved Liver Diffusion-Weighted Imaging at 3 T Using Respiratory Triggering in Combination With Simultaneous Multislice Acceleration

Tavakoli, Andrej MD*,†; Attenberger, Ulrike I. MD*; Budjan, Johannes MD*; Stemmer, Alto MSc; Nickel, Dominik PhD; Kannengiesser, Stephan PhD; Morelli, John N. MD§; Schoenberg, Stefan O. MD*; Riffel, Philipp MD*

doi: 10.1097/RLI.0000000000000594
Original Articles
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Objectives The aim of this study was to retrospectively compare optimized respiratory-triggered diffusion-weighted imaging with simultaneous multislice acceleration (SMS-RT-DWI) of the liver with a standard free-breathing echo-planar DWI (s-DWI) protocol at 3 T with respect to the imaging artifacts inherent to DWI.

Materials and Methods Fifty-two patients who underwent a magnetic resonance imaging study of the liver were included in this retrospective study. Examinations were performed on a 3 T whole-body magnetic resonance system (MAGNETOM Skyra; Siemens Healthcare, Erlangen, Germany). In all patients, both s-DWI and SMS-RT-DWI of the liver were obtained. Images were qualitatively evaluated by 2 independent radiologists with regard to overall image quality, liver edge sharpness, sequence-related artifacts, and overall scan preference. For quantitative evaluation, signal-to-noise ratio was measured from signal-to-noise ratio maps. The mean apparent diffusion coefficient (ADC) was measured in each liver quadrant. The Wilcoxon rank-sum test was used for analysis of the qualitative parameters and the paired Student t test for quantitative parameters.

Results Overall image quality, liver edge sharpness, and sequence-related artifacts of SMS-RT-DWI received significantly better ratings compared with s-DWI (P < 0.05 for all). For 90.4% of the examinations, both readers overall preferred SMS-RT-DWI to s-DWI. Acquisition time for SMS-RT-DWI was 34% faster than s-DWI. Signal-to-noise ratio values were significantly higher for s-DWI at b50 but did not statistically differ at b800, and they were more homogenous for SMS-RT-DWI, with a significantly lower standard deviation at b50. Mean ADC values decreased from the left to right hepatic lobe as well as from cranial to caudal for s-DWI. With SMS-RT-DWI, mean ADC values were homogeneous throughout the liver.

Conclusions Optimized, multislice, respiratory-triggered DWI of the liver at 3 T substantially improves image quality with a reduced scan acquisition time compared with s-DWI.

From the *Department of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Mannheim

Department of Radiology, German Cancer Research Center, Heidelberg

Siemens Healthineers, Erlangen, Germany

§Department of Radiology, St John's Medical Center, Tulsa, OK.

Received for publication April 15, 2019; and accepted for publication, after revision, May 22, 2019.

Conflicts of interest and sources of funding: none declared.

Correspondence to: Andrej Tavakoli, MD, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany. E-mail: s.tavakoli@gmx.de.

Online date: July 17, 2019

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