Diffusion kurtosis imaging (DKI) of hepatocellular carcinoma: correlation with microvascular invasion and histologic grade

Abstract

Background: The aim of this study was to prospectively evaluate the diagnostic efficacy of diffusion kurtosis imaging (DKI) in predicting microvascular invasion (MVI) and histologic grade of hepatocellular carcinoma (HCC) with comparison to the conventional diffusion-weighted imaging (DWI). Methods: This prospective study was approved by the Institutional Review Board, and written informed consent was obtained from all patients. From September 2015 to January 2017, 74 consecutive HCC patients were enrolled in this study. Preoperative magnetic resonance imaging including DKI protocol was performed, and patients were followed up for at least one year after surgery. Diffusion parameters including the mean corrected apparent diffusion coefficient (MD), mean apparent kurtosis coefficient (MK), and apparent diffusion coefficient (ADC) were calculated. Differences of diffusion parameters among different histopathological groups were compared. For parameters that were significantly different between pathological groups, receiver operating characteristics (ROC) curve analyses were performed to evaluate the diagnostic efficiency for identifying MVI and predicting high-grade HCC. Univariate and multivariate logistic regression analyses were used to evaluate the relative value of clinical and laboratory variables and diffusion parameters as risk factors for early recurrence (≤1 year). Results: Among all the studied diffusion parameters, only MK differed significantly between the MVIpositive and MVI-negative group (0.91±0.10 vs. 0.82±0.09, P<0.001), and showed moderate diagnostic efficacy (AUC =0.77) for identifying MVI. High-grade HCCs showed significantly higher MK values (0.93±0.10 vs. 0.82±0.09, P<0.001), along with MD (1.34±0.18 vs. 1.54±0.22, P<0.001) and ADC values (1.17±0.15 vs. 1.30±0.16, P=0.001) than low-grade HCCs. For differentiating high-grade from low-grade HCCs, MK demonstrated a higher area under the ROC curve (AUC) and significantly higher specificity than MD and ADC (AUC =0.81 vs. 0.76 and 0.74; specificity =82.2% vs. 60.0% and 60.0%, P=0.02). In addition, higher MK (OR =5.700, P=0.002) and Barcelona Clinic Liver Cancer (BCLC) stage C (OR =6.329, P=0.005) were independent risk factors for early HCC recurrence. Conclusions: DKI-derived MK values outperformed conventional ADC values for predicting MVI and histologic grade of HCC, and are associated with increased risk of early tumor recurrence.

The Diagnostic Performance of Diffusion Kurtosis Imaging in the Characterization of Breast Tumors: A Meta-Analysis

“…The diffusion of water molecules in this microenvironment will deviate from the mono-exponential Gaussian model at high b-values, leading to inaccurate fitting and calculation of the diffusion coefficient. Considering the above factors, a DKI non-Gaussian model was developed and showed improved diagnostic performance for prostate cancer (37), hepatocellular carcinoma (38), and glioma (39) as well as for breast tumors in our study. DKI can add valuable implications of microstructural changes to the findings of conventional DCE-MRI, whose pooled specificity was only 71% in a previous meta-analysis (40).…”

<p>Amide Proton Transfer Imaging vs Diffusion Kurtosis Imaging for Predicting Histological Grade of Hepatocellular Carcinoma</p>

“…The details of the calculation formulas and data processing of the APTand DKI-derived parameters have been reported in previous studies. 10,14 Two of the authors (BLW and FJ, with seven and five years of experience in liver MR imaging, respectively) who were blinded to the histopathological results independently performed the data analysis. First, on the largest diameter of the tumor, a boundary was drawn along the tumor edge on the original APT and DKI images by referring to the tumor contour on the conventional T 1and T 2 -weighted images.…”

“…For patients with multifocal lesions, the one with the largest diameter was chosen for analysis according to a previous study. 10…”

“…A recent study compared DKI-derived parameters with conventional DWI in predicting the histological grade of HCC, and suggested that DKI-derived MK was superior to conventional ADC for predicting the HCC grade. 10 Thus, to develop a more useful and noninvasive tool to evaluate the HCC grade, our study mainly focused on evaluating the value of APT imaging in the evaluation of HCC grade, with comparison with DKI. The potential value of APT imaging in estimating the histologic grades of tumors, such as SCCC, 15,21 diffuse gliomas, 16 and EEA, 14 has been demonstrated by previous studies.…”

“…9 Moreover, a recent study revealed that DKI was superior to conventional DWI in predicting the microvascular invasion and histological grade of HCC. 10 Amide proton transfer (APT) imaging, which was proposed by Zhou et al in 2013, 11 is a kind of chemical exchange saturation transfer (CEST) imaging. It mainly measures the chemical transfer characteristics of amide protons located at 3.5 ppm, which can indirectly determine the content of endogenous mobile proteins and polypeptides.…”