Diffusion-weighted MR imaging of pancreatic cancer: A comparison of mono-exponential, bi-exponential and non-Gaussian kurtosis models

Abstract

ObjectivesTo compare two Gaussian diffusion-weighted MRI (DWI) models including mono-exponential and bi-exponential, with the non-Gaussian kurtosis model in patients with pancreatic ductal adenocarcinoma.Materials and methodsAfter written informed consent, 15 consecutive patients with pancreatic ductal adenocarcinoma underwent free-breathing DWI (1.5T, b-values: 0, 50, 150, 200, 300, 600 and 1000 s/mm2). Mean values of DWI-derived metrics ADC, D, D*, f, K and DK were calculated from multiple regions of interest in all tumours and non-tumorous parenchyma and compared. Area under the curve was determined for all metrics.ResultsMean ADC and DK showed significant differences between tumours and non-tumorous parenchyma (both P < 0.001). Area under the curve for ADC, D, D*, f, K, and DK were 0.77, 0.52, 0.53, 0.62, 0.42, and 0.84, respectively.ConclusionADC and DK could differentiate tumours from non-tumorous parenchyma with the latter showing a higher diagnostic accuracy. Correction for kurtosis effects has the potential to increase the diagnostic accuracy of DWI in patients with pancreatic ductal adenocarcinoma.

Recent Advances in Pancreatic MR Imaging: A Guide on How, When, and Why to Perform

“…The parameters obtained from DKI are mean kurtosis (MK) and corrected diffusion coefficient (D K ). D K is shown to be able to differentiate between tumor and normal tissue, 49 correlate with HbA1 c levels, and may potentially serve as a biomarker of glycemic control. 50…”

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“…However, due to the interaction of water molecules with microstructural components such as cell membranes, there will be a deviation from pure Gaussian diffusion. A correction to the models above is to take account for this non-Gaussian diffusion behaviour by an additional fit parameter, the kurtosis coefficient K , which is derived along with the kurtosis-corrected diffusion coefficient [25] , [26] . K might contain information about the microstructural organization of the tissue which is complementary to the perfusion- and diffusion-based parameters contained in the mono-exponential and the IVIM model.…”

“…One pre-requisite for using this model is the acquisition of very high b -values, which should exceed 1000 [25] . There is only a limited number of studies applying this model for RT applications so far, but some promising results have been published recently [26] , [27] , [28] .…”

“…Voxel-based DWI analysis might be of value for tumor delineation, e.g. in esophageal tumors [68] , pancreatic cancer [26] , as well as for glioblastoma [69] . In cervical cancer, DWI might have an impact on the definition of high-risk clinical target volumes [70] .…”

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“…b-Value optimized DWI can be used to increase lesion conspicuity 82 and sensitivity for small NETs. 83 Pancreatic malignancy is associated with reduced ADC [84][85][86][87] and reduced fractional anisotropy 84 relative to adjacent normal pancreatic tissue ( Supplementary Material 1). Studies using DWI to distinguish inflammatory and malignant solid pancreatic lesions, have been less conclusive with some demonstrating lower ADC in malignancy [88][89][90][91][92] and others showing no difference.…”