Effects of Echo Time on IVIM Quantification of the Normal Prostate

Zhaoyan Feng,Peipei Zhang,Xiangde Min,Basen Li,Liang Wang,Huijuan You,Zan Ke,Xu Yan

doi:10.1038/s41598-018-19150-2

Abstract

The two-compartment intravoxel incoherent motion (IVIM) theory assumes that the transverse relaxation time is the same in both compartments. However, blood and tissue have different T2 values, and echo time (TE) may thus have an effect on the quantitative parameters of IVIM. The purpose of this study was to investigate the effects of TE on IVIM-DWI-derived parameters of the prostate. In total, 17 healthy volunteers underwent two repeat examinations. IVIM-DWI data were scanned 6 times with variable TE values of 60, 70, 80, 90, 100, and 120 ms. The ADC of a mono-exponential model and the D, D*, and f parameters of the IVIM model were calculated separately for each TE. Repeat measures were assessed by calculating the coefficient of variation and Bland-Altman limits of agreement for each parameter. Spearman’s rho test was used to analyse relationships between IVIM indices and TE. Our results showed that TE had an effect on IVIM quantification, which should be kept constant in the examination protocol at each individual institution. Alternatively, an extended IVIM could be used to eliminate the effect of the TE value on the quantitative parameters of IVIM. This may be helpful for guiding clinical research, especially for longitudinal studies.

Highlights

The stability of DWI-derived quantitative parameters is a prerequisite for their use as imaging biomarkers in clinical studies
No report has examined the effect of TE value on prostate intravoxel incoherent motion (IVIM) quantitative parameters, the 2012 PI-RADS v1 prostate MR guideline suggests that the TE should be as short as achievable in prostate DWI10
With TE values in the range of 60–120 ms, the coefficient of variation (CV) of the ADC and D values in the peripheral zone (PZ) were in the range of 1.641–2.635%, and the ranges of the Bland-Altman limits of agreement (BA-LA) were −4.965% to 4.263% and −6.889% to 7.453%, respectively

Summary

Introduction

The stability of DWI-derived quantitative parameters is a prerequisite for their use as imaging biomarkers in clinical studies. Blood and tissue have different T2 values, and echo time (TE) may have an effect on the quantitative parameters of IVIM. Jerome et al.[9] reported that DWI scanning using the shortest TE value overestimated the f value of liver tissue. No report has examined the effect of TE value on prostate IVIM quantitative parameters, the 2012 PI-RADS v1 prostate MR guideline suggests that the TE should be as short as achievable (typically

Objectives

Methods

Results

Conclusion