Diffusion-weighted Imaging of the Liver with MultiplebValues: Effect of Diffusion Gradient Polarity and Breathing Acquisition on Image Quality and Intravoxel Incoherent Motion Parameters—A Pilot Study

Abstract

Purpose:To optimize intravoxel incoherent motion (IVIM) diffusion-weighted (DW) imaging by estimating the effects of diffusion gradient polarity and breathing acquisition scheme on image quality, signal-to-noise ratio (SNR), IVIM parameters, and parameter reproducibility, as well as to investigate the potential of IVIM in the detection of hepatic fibrosis. Materials and Methods:In this institutional review board-approved prospective study, 20 subjects (seven healthy volunteers, 13 patients with hepatitis C virus infection; 14 men, six women; mean age, 46 years) underwent IVIM DW imaging with four sequences: (a) respiratory-triggered ( Mixed-model analysis of variance was used to compare image quality, SNR, IVIM parameters, and interexamination variability between the four sequences, as well as the ability to differentiate areas of liver fibrosis from normal liver tissue. Results:Image quality with RT sequences was superior to that with FB acquisitions (P = .02) and was not affected by gradient polarity. SNR did not vary significantly between sequences. IVIM parameter reproducibility was moderate to excellent for PF and D, while it was less reproducible for D*. PF and D were both significantly lower in patients with hepatitis C virus than in healthy volunteers with the RT BP sequence (PF = 13.5% 6 5. Conclusion:The RT BP DW imaging sequence had the best results in terms of image quality, reproducibility, and ability to discriminate between healthy and fibrotic liver with biexponential fitting.q RSNA, 2012

Liver intravoxel incoherent motion (IVIM) magnetic resonance imaging: a comprehensive review of published data on normal values and applications for fibrosis and tumor evaluation

“…Various fitting algorithms have been used to determine IVIM parameters, including asymptotic fitting (9)(10)(11)(12)(19)(20)(21)24,41,45,46,48,51,53), nonlinear least square (usually Levenberg-Marquardt) fitting (23,42,47,52,54,55), and Bayesian fitting (15,22,40,43,50). Current review cannot draw conclusion which one is better than others, nor can the mean values be compared (Figure 8).…”

“…Dyvorne et al (15) found that RT sequence has higher image quality than FB sequences, the latter being much more prone to motionrelated blurring. Additionally, left lobe may be more prone to cardiac motion artifacts which potentially can alter diffusion measurement (15). However, Barbieri et al found that the use of RT did not have a significant effect on the measured parameter values (37).…”

“…A prerequisite to translating the growing interest in IVIM imaging into clinical applications is its accurate measurement of normative value of IVIM parameters and acceptable reproducibility across different clinical settings (13,14). Nevertheless, accurate IVIM quantification is challenging, partially due to the limited sampling and low signal-to-noise ratio (SNR) for fast data acquisition of the liver (15)(16)(17). Even in the brain, where there is almost no motion effect, the cross-center agreement has been recently shown to be sub-optimal.…”

Effect of Food Intake on Intravoxel Incoherent Motion and T2* in the Healthy Liver

“…Large values of standard deviation of D * was the one of the reasons. Some reports showed D * and PF are not reproducible [9][10][11]. In addition, some reports showed that the standard deviation and its coefficient of variation in D * and PF are large [7,11].…”

“…Some reports showed D * and PF are not reproducible [9][10][11]. In addition, some reports showed that the standard deviation and its coefficient of variation in D * and PF are large [7,11]. 2 were suitable to evaluate microperfusion [1,12].…”