Inter-observer reproducibility of quantitative dynamic susceptibility contrast and diffusion MRI parameters in histogram analysis of gliomas

Abstract

Background Dynamic-susceptibility contrast and diffusion-weighted imaging are promising techniques in diagnosing glioma grade. Purpose To compare the inter-observer reproducibility of multiple dynamic-susceptibility contrast and diffusion-weighted imaging parameters and to assess their potential in differentiating low- and high-grade gliomas. Material and Methods Thirty patients (16 men; mean age = 40.6 years) with low-grade (n = 13) and high-grade (n = 17) gliomas and known pathology, scanned with dynamic-susceptibility contrast and diffusion-weighted imaging were included retrospectively between March 2006 and March 2014. Three observers used three different methods to define the regions of interest: (i) circles at maximum perfusion and minimum apparent diffusion coefficient; (ii) freeform 2D encompassing the tumor at largest cross-section only; (iii) freeform 3D on all cross-sections. The dynamic-susceptibility contrast curve was analyzed voxelwise: maximum contrast enhancement; time-to-peak; wash-in rate; wash-out rate; and relative cerebral blood volume. The mean was calculated for all regions of interest. For 2D and 3D methods, histogram analysis yielded additional statistics: the minimum and maximum 5% and 10% pixel values of the tumor (min5%, min10%, max5%, max10%). Intraclass correlations coefficients (ICC) were calculated between observers. Low- and high-grade tumors were compared with independent t-tests or Mann–Whitney tests. Results ICCs were highest for 3D freeform (ICC = 0.836–0.986) followed by 2D freeform (ICC = 0.854–0.974) and circular regions of interest (0.141–0.641). High ICC and significant discrimination between low- and high-grade gliomas was found for the following optimized parameters: apparent diffusion coefficient ( P < 0.001; ICC = 0.641; mean; circle); time-to-peak ( P = 0.015; ICC = 0.986; mean; 3D); wash-in rate ( P = 0.004; ICC = 0.826; min10%; 3D); wash-out rate ( P < 0.001; ICC = 0.860; min10%; 2D); and relative cerebral blood volume ( P ≤ 0.001; ICC = 0.961; mean; 3D). Conclusion Dynamic-susceptibility contrast perfusion parameters relative cerebral blood volume and time-to-peak yielded high inter-observer reproducibility and significant glioma grade differentiation for the means of 2D and 3D freeform regions of interest. Choosing a freeform 2D method optimizes observer agreement and differentiation in clinical practice, while a freeform 3D method provides no additional benefit.

Assessment of the hypervascularized fraction of glioblastomas using a volume analysis of dynamic susceptibility contrast-enhanced MRI may help to identify pseudoprogression

“…In another study, Dijkstra et al . showed that freeform ROIs that encompassed the whole tumour had a good diagnostic accuracy in differentiating low grade from high grade tumour [ 29 ]. In accordance with these results, we suggest that exclusion of the necrotic centre could be skipped from routine post-processing without preventing the distinction between pseudoprogression and tumour progression.…”

Reproducibility of rCBV in glioblastomas using T2*-weighted perfusion MRI: an evaluation of sampling, normalization, and experience

“…Despite its operator dependency and inter-observer variability, this is the most widely used method in clinical practice. 9 , 10 , 11 , 12 …”

Variability of relative cerebral blood volume measurements of recurrent glioma

“…Dijkstra et al proved that out of all the parameters to compare on MRI, rCBV was the most reproducible between observers (other parameters included apparent diffusion coefficient, maximum contrast enhancement, time to peak, wash in rate, and wash out rate) (7). They also determined that single slice ROI selection is not significantly different from attempting to capture the whole tumor in a 3D; thus, 2D selection is sufficient.…”