Nonlinear distortion correction of diffusion MR images improves quantitative DTI measurements in glioblastoma

Abstract

The purpose of this study was to use a retrospective nonlinear distortion correction technique and evaluate the changes in DTI metrics in areas of interest in and around GBM tumors. A total of 24 histologically confirmed GBM patients with pre-operative 20-direction DTI scans were examined. Variability in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in normal tissue before and after distortion correction were examined. Changes in mean, median and variance of ADC and FA in contrast enhancing and T2/FLAIR ROIs were also examined with and without distortion correction. Results suggest the intra-subject standard deviations of ADC and FA decreased in normal tissue after the application of distortion correction (P<0.0001). FA mean and median values decreased after distortion correction in both T1+C and T2 ROIs (P<0.017), while ADC mean and median values did not significantly change except for the median ADC in T1+C ROIs (P=0.0054). The intra-subject standard deviation of ADC and FA values in tumor ROIs changed significantly with distortion correction, and Bland-Altman analysis indicated that the bias and the standard deviation of the bias of these intra-subject standard deviations were larger than those of the mean and median terms. Additionally, the means of the two curves of a double Gaussian fit to the histogram of ADC values from T1+C ROIs, ADCL (mean of lower Gaussian) as well as ADCH (mean of the higher Gaussian) were found to change significantly with distortion correction (P=0.0045 for ADCL and P=0.0370 for ADCH). Nonlinear distortion correction better aligns neuro-anatomical structures between DTI and anatomical scans, and significantly alters the measurement of values within tumor ROIs for GBM patients.

Diffusion MRI Phenotypes Predict Overall Survival Benefit from Anti-VEGF Monotherapy in Recurrent Glioblastoma: Converging Evidence from Phase II Trials

“…Additionally, image distortions on diffusion MR images obtained using echo planar imaging may have led to inaccuracies when estimating the ADC characteristics within the contrast-enhancing lesion. Estimates of ADC L , however, have been shown to be relatively robust even in the presence of distortion (30) and results from the current study suggest a COV of only 2.5%, suggesting image distortion may not have been a critical limitation. Additionally, more in-depth baseline characteristics, including information about post-progressive treatment and molecular information, were not available for the trials used in the current study.…”

“…Goodness of fit was determined to be adequate if the adjusted R 2 > 0.7. This approach is similar to those used previously (18–20, 30). …”

The orthotopic xenotransplant of human glioblastoma successfully recapitulates glioblastoma-microenvironment interactions in a non-immunosuppressed mouse model

“…In our model, despite the incompatibility of major histocompatibility complex (MHC), we observed the development of a tumor mass in immunocompetent mice inoculated with human GBM cells. MRI analysis of xenografted mice showed a growing tumor mass (Additional file 1 ) which enhanced with MR contrast, evidencing, BBB disruption (Figure 1 ), and the presence of necrotic/hemorrhagic spots in the core of the tumor mass, similar to what is described in GBM patients [ 10 ]. Moreover, we also observed the same histopathological features present in GBM patients [ 9 ] as described by the WHO (Figure 2 ).…”

“…In addition, GBM is one of the most angiogenic tumors [ 7 , 8 ]. The presence of glomeruloid vessels is an important feature for diagnosis through histopathological analysis, as well as cellular atypia, necrosis, and mitotic figures [ 9 , 10 ].…”

Diffusion MRI quality control and functional diffusion map results in ACRIN 6677/RTOG 0625: A multicenter, randomized, phase II trial of bevacizumab and chemotherapy in recurrent glioblastoma

“…Another potential limitation was the potential influence of geometric distortions on ADC measurements. Woodworth et al ( 20 ) recently showed that post hoc non-linear distortion correction of diffusion MR images to high-resolution T2-weighted images can improve diffusion measurements in brain tumors, demonstrating that subtle distortions can cause significant differences in ADC measurements. A similar approach could have been used in the present study to improve ADC measurements, even in patients with usable data (QC ≥3).…”