Short-Term Reproducibility of Intravoxel Incoherent Motion Parameters and Apparent Diffusion Coefficient of Large Hepatocellular Carcinoma
Lifang Wu1

1Fudan University, Shanghai, China, People's Republic of

Synopsis

More and more studies have been attributed to the evaluation of IVIM analysis for disease characterization or response assessment, but its measurement reproducibility when applied in clinical practice and research still be in controversial. There is only few prior research on repeatability of IVIM-derived parameters of hepatocellular carcinoma (HCC) as well as the choice of free-breathing (FB). In this study we used our own data to explore the reproducibility of IVIM-derived parameters, ADC(0,500) and ADCtotal of HCC.

Purpose

To determine the measurement reproducibility of IVIM (intravoxel incoherent motion) diffusion parameters, ADC (apparent diffusion coefficient) (0,500) and ADCtotal of large Hepatocellular carcinoma.

Materials and Methods

Twenty-seven patients (31 lesions) with primary HCC underwent MRI examinations including two repeat IVIM DWI sequences with 12 b values (0, 10, 20, 30, 40, 50, 70, 100, 200, 300, 500, 800 s/mm2). Regions of interest (ROIs) were drawn within the outer border 1 mm from peripheral margin of the selected HCC(Figure) to derive intravoxel incoherent motion (IVIM) parameters D, D*, and PF, ADC(0,500) and ADCtotal (all 12 b values) by a Bayesian method. Short-term measurement reproducibility of IVIM parameters and ADCs were assessed by measuring interclass correlation coefficients (ICCs), coefficient of variation (CV) and Bland–Altman limits of agreements (BA-LA).

Results

The intra- and interobserver ICCs were good for HCC except for D⃰ value ranging from 0.829 to 0.946. The reproducibility was good For D and ADCtotal (CV 15.5%, 14.4% and 13.1%, 10.8% respectively) and was poor for D⃰ and PF (CV values were >30%) for both first and second DWI series, thus suggesting less variability of D and ADCtotal. The strongest 95 % Bland–Altman limits for agreements (BA-LA) of short-term measurement reproducibility was noted for ADCtotal (-15.9% to 18.2%), followed by D (-21.0% to 30.7%) and ADC(0,500) (-37.6% to 46.7%). Very wide 95 % confidence limits were observed for D⃰ (-115.1% to 128.7%) and PF(−96.7% to 98.0 %). The reproducibility of IVIM Parameters and ADCs for lesions 50 mm or larger in diameter was better than that for lesions smaller than 50 mm.

Conclusion

D* and PF are perfusion-sensitive parameters calculated from low b values at which blood magnetization dominates the signal attenuation, they are potentially more sensitive to measurement uncertainty resulting from capillary perfusion and signal to noise variations, thus D⃰ and PF show considerable measurement variability[1,2]. D and ADCtotal may be potentially more meaningful quantitative parameters in clinical practice and the larger lesion is preferable when applying ADCs from DW imaging to the monitoring of treatment response of hepatic disease, as using more b values gives more accurate ADC value, especially where the likely ADC values are not kown a priori, at higher b values, pseudodiffusion account for only a small proportion of the measured signal in each imaging voxel and may tease out the effects of microcapillary perfusion[3]. The larger lesion is preferable when applying ADCs from DW imaging to the monitoring of treatment response of hepatic disease. Yeon Kim Set al[4] turned out that ADC measurement of malignant hepatic tumors tended to be more reproducible for larger rather than smaller lesions, they pointed out that this may have resulted from the partial volume averaging effect, which probably more severely affected the ADC measurement of smaller lesions.

Acknowledgements

More and more studies have been attributed to the evaluation of IVIM analysis for disease characterization or response assessment, but its measurement reproducibility when applied in clinical practice and research still be in controversial. There is only few prior research on repeatability of IVIM-derived parameters of hepatocellular carcinoma (HCC) as well as the choice of free-breathing (FB). In this study we used our own data to explore the reproducibility of IVIM-derived parameters, ADC(0,500) and ADCtotal of HCC.

References

[1]Kakite S, Dyvorne H, Besa C, et al. Hepatocellular carcinoma: short-term reproducibility of apparent diffusion coefficient and intravoxel incoherent motion parameters at 3.0T[J]. J Magn Reson Imaging,2015,41(1):149-156.

[2] Dyvorne H A, Galea N, Nevers T, et al. Diffusion-weighted imaging of the liver with multiple b values: effect of diffusion gradient polarity and breathing acquisition on image quality and intravoxel incoherent motion parameters--a pilot study[J]. Radiology,2013,266(3):920-929.

[3] Koh D M, Collins D J, Orton M R. Intravoxel incoherent motion in body diffusion-weighted MRI: reality and challenges[J]. AJR Am J Roentgenol,2011,196(6):1351-1361.

[4] Yeon Kim S, Soo Lee S, Ho Byun, J, et al.Malignant Hepatic Tumors: Short- term Reproducibility of Apparent Diffusion Coeffi cients with Breath-hold and Respiratory-triggered Diffusion- weighted MR Imaging 1[J]. Radiology,2010,255(3):815-823.

Figures

D map calculated from IVIM diffusion-weighted imaging data

Dfast map calculated from IVIM diffusion-weighted imaging data

PF map calculated from IVIM diffusion-weighted imaging data

ADC(0,500) map with b value of 0 and 500 sec/mm2

ADCtotal map with all 12 b values.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
2958