Gregory O. Cron, Presenter: Nothing to Disclose

Thanh Nguyen MD, Abstract Co-Author: Nothing to Disclose

Jean-Francois Mercier MD, Abstract Co-Author: Nothing to Disclose

Claire Foottit MSc, PhD, Abstract Co-Author: Nothing to Disclose

Rebecca E Thornhill MSc, PhD, Abstract Co-Author: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Consultant, Paradigm Spine LLC Consultant, Pfizer Inc

John Woulfe MD, Abstract Co-Author: Nothing to Disclose

Carlos Hernando Torres MD, Abstract Co-Author: Nothing to Disclose

Santanu Chakraborty FRCR, Abstract Co-Author: Nothing to Disclose

John Sinclair, Abstract Co-Author: Nothing to Disclose

Ian Cameron, Abstract Co-Author: Nothing to Disclose

Jean-Michel Caudrelier MD, Abstract Co-Author: Nothing to Disclose

The perfusion parameter Ktrans is an assessment of blood flow and capillary permeability measured with dynamic contrast-enhanced (DCE) MRI, and correlates well with glioma grade. Prior approaches for analyzing DCE-MRI data are prone to errors caused by variable MRI signal nonlinearity and blood inflow effects, both limiting accuracy and reproducibility. We demonstrate an approach which minimizes these errors through the use of bookend T1 measurements (providing accurate tissue response functions) and phase measurements in blood (providing accurate arterial input functions).

At 1.5T, 31 patients with cerebral gliomas were imaged and correlated with histology. DCE-MRI was performed with double-echo 2D FLASH (TR/TE/flip 50ms/2.1 & 5.5 ms/90º). Gd concentration-vs-time in tissue and blood were obtained by two different approaches: 1) percent enhancement; and 2) bookend T1 measurements (for tissue) and MR signal phase (for blood). Tracer kinetic modeling was used to obtain parametric Ktrans maps in a 5-mm maximal ROI.  Student t-test determined the significance of the difference in Ktrans values between low- and high-grade gliomas.  ROC analysis determined sensitivity, specificity, and AUC of each approach for correctly identifying high grade gliomas.  Z statistic was used to compare AUCs.  Sensitivity and specificity of conventional MRI with contrast (evaluated by an experienced radiologist) was also measured.

8 gliomas were low grade (II) and 23 were high grade (III-IV). For the “traditional” approach, Ktrans values for low and high grade tumors were 0.07 ± 0.15 min-1 and 0.14 ± 0.15 min-1, respectively (p=0.26). Sensitivity & specificity were 87% & 63%, respectively (threshold=0.0039 min-1).  AUC was 0.72 (95% CI 0.53 to 0.86).  For the new approach, Ktrans values for low and high grade were 0.02 ± 0.03 min-1 and 0.09 ± 0.05 min-1 (p=0.0003).  Sensitivity & specificity were 83% & 88% (threshold=0.0355 min-1).  AUC was 0.88 (95% CI 0.71 to 0.97).  AUC of the new approach was significantly higher than that of the “traditional” approach (p=0.01).  Conventional MRI achieved a sensitivity & specificity of 96% & 63%.

We have successfully implemented an approach for more accurate and potentially reproducible measurement of Ktrans in cerebral gliomas. This improves glioma grading compared to current approaches.

Ktrans shows potential for distinguishing low- from high- grade cerebral gliomas.

Cron, G, Nguyen, T, Mercier, J, Foottit, C, Thornhill, R, Schweitzer, M, Woulfe, J, Torres, C, Chakraborty, S, Sinclair, J, Cameron, I, Caudrelier, J, Towards a More Error-free and Reproducible-enhanced MR Glioma Grading: Bookend T1 with Phase-derived Arterial Input Functions.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11003411.html