Mono, bi- and tri-exponential diffusion MRI modelling for renal solid masses and comparison with histopathological findings

Abstract

PurposeTo compare diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM), and tri-exponential models of the diffusion magnetic resonance imaging (MRI) signal for the characterization of renal lesions in relationship to histopathological findings.MethodsSixteen patients planned to undergo nephrectomy for kidney tumour were scanned before surgery at 3 T magnetic resonance imaging (MRI), with T2-weighted imaging, DTI and diffusion weighted imaging (DWI) using ten b-values. DTI parameters (mean diffusivity [MD] and fractional anisotropy [FA]) were obtained by iterative weighted linear least squared fitting of the DTI data and bi-, and tri-exponential fit parameters (Dbi, fstar,and Dtri, ffast,finterm) using a nonlinear fit of the multiple b-value DWI data. Average parameters were calculated for regions of interest, selecting the lesions and healthy kidney tissue. Tumour type and specificities were determined after surgery by histological examination. Mean parameter values of healthy tissue and solid lesions were compared using a Wilcoxon-signed ranked test and MANOVA.ResultsThirteen solid lesions (nine clear cell carcinomas, two papillary renal cell carcinoma, one haemangioma and one oncocytoma) and four cysts were included. The mean MD of solid lesions are significantly (p < 0.05) lower than healthy cortex and medulla, (1.94 ± 0.32*10− 3 mm2/s versus 2.16 ± 0.12*10− 3 mm2/s and 2.21 ± 0.14*10− 3 mm2/s, respectively) whereas ffast is significantly higher (7.30 ± 3.29% versus 4.14 ± 1.92% and 4.57 ± 1.74%) and finterm is significantly lower (18.7 ± 5.02% versus 28.8 ± 5.09% and 26.4 ± 6.65%). Diffusion coefficients were high (≥2.0*10− 3 mm2/s for MD, 1.90*10− 3 mm2/s for Dbi and 1.6*10− 3 mm2/s for Dtri) in cc-RCCs with cystic structures and/or haemorrhaging and low (≤1.80*10− 3 mm2/s for MD, 1.40*10− 3 mm2/s for Dbi and 1.05*10− 3 mm2/s for Dtri) in tumours with necrosis or sarcomatoid differentiation.ConclusionParameters derived from a two- or three-component fit of the diffusion signal are sensitive to histopathological features of kidney lesions.Electronic supplementary materialThe online version of this article (10.1186/s40644-018-0178-0) contains supplementary material, which is available to authorized users.

An optimized b‐value distribution for triexponential intravoxel incoherent motion (IVIM) in the liver

“…Table 1 provides an overview of currently published values. One thing to note is that reported in Riexinger et al 15 is roughly by 1 order of magnitude larger than the values reported in the other publications, 5,10,11,13,14 which most likely can be attributed to the lower minimal b‐value used in Riexinger et al 15 The optimization performed here is based on the assumption that these large values are a good representation of the real values and that consequently very small b‐values, say below 1 s/mm 2 , are needed to sample such large values. Triexponential IVIM parameters obtained with such very small b‐values have so far been reported only for the liver to our knowledge.…”

“…Here, f 1 and f 2 represent perfusion fractions, and D * 1 and D * 2 represent the pseudo-diffusion coefficients. 5,[10][11][12][13][14][15] These additionally obtainable quantitative parameters might be useful, for example, to separate benign and malignant lesions as it was demonstrated for biexponential IVIM (e.g., Cho et al and Murtz et al). 16,17 More interesting, however, might be the exploration of the nature of the triexponential IVIM effect, because it could unveil general properties of the IVIM effect.…”

“…Here, and represent perfusion fractions, and and represent the pseudo‐diffusion coefficients 5,10‐15 . These additionally obtainable quantitative parameters might be useful, for example, to separate benign and malignant lesions as it was demonstrated for biexponential IVIM (e.g., Cho et al and Murtz et al) 16,17 .…”

Spectral diffusion analysis of kidney intravoxel incoherent motion MRI in healthy volunteers and patients with renal pathologies

“…54 These findings are in line with earlier studies, where the intermediate pseudo-diffusion was speculated to be attributable to the freely diffusing water. 14,15,55 The investigated renal cell carcinoma demonstrated quite a different diffusion spectrum pattern compared to the healthy kidney. We argue that the decreased f interm and, at the same time, increased f slow , might be due to a mechanical hindrance of water motion caused by the diffusion-restricting elements such as cell membranes and macromolecules.…”

Combinative evaluation of primary tumor and lymph nodes to predict pelvic lymphatic metastasis in cervical cancer: an integrated PET-IVIM MRI study

“…In the IVIM model, D and f value are indicators to reflect the true diffusion coefficient and perfusion information of the molecule, respectively. IVIM modalities have also been used in other cervical cancer studies [21,22]. However, the current IVIM technology still has shortcomings and has not been applied on a large scale in the clinic setting.…”