Dinil Sasi S1, Rakesh K Gupta2, Rana Patir3, Suneeta Ahlawat4, Sandeep Vaishya3, Anup Singh5. 1. Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India. 2. Department of Radiology and Imaging, Fortis Memorial Research Institute, Gurugram, India. 3. Department of Neurosurgery, Fortis Memorial Research Institute, Gurugram, India. 4. SRL Diagnostics, Fortis Memorial Research Institute, Gurugram, India. 5. Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India; Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi, India. Electronic address: anupsm@iitd.ac.in.
Abstract
RATIONALE AND OBJECTIVES: To comprehensively evaluate robustness and variations of DCE-MRI derived generalized-tracer-kinetic-model (GTKM) parameters in healthy and tumor tissues and impact of normalization in mitigating these variations on application to glioma. MATERIALS (PATIENTS) AND METHODS: A retrospective study included pre-operative 31 high-grade-glioma(HGG), 22 low-grade-glioma(LGG) and 33 follow-up data from 10 patients a prospective study with 4 HGG subjects. Voxel-wise GTKM was fitted to DCE-MRI data to estimate Ktrans, ve, vb. Simulations were used to evaluate noise sensitivity. Variation of parameters with-respect-to arterial-input-function (AIF) variation and data length were studied. Normalization of parameters with-respect-to mean values in gray-matter (GM) and white-matter (WM) regions (GM-Type-2, WM-Type-2) and mean curves (GM-Type-1, WM-Type-1) were also evaluated. Co-efficient-of-variation(CoV), relative-percentage-error (RPE), Box-Whisker plots, bar graphs and t-test were used for comparison. RESULTS: GTKM was fitted well in all tissue regions. Ktrans and ve in contrast-enhancing (CE) has shown improved noise sensitivity in longer data. vb was reliable in all tissues. Mean AIF and C(t) peaks showed ~38% and ~35% variations. During simulation, normalizations have mitigated variations due to changes in AIF amplitude in Ktrans and vb.. ve was less sensitive to normalizations. CoV of Ktrans and vb has reduced ~70% after GM-Type-1 normalization and ~80% after GM-Type-2 normalization, respectively. GM-Type-1 (p = 0.003) and GM-Type-2 (p = 0.006) normalizations have significantly improved differentiation of HGG and LGG using Ktrans. CONCLUSION: Ktrans and vb can be reliably estimated in normal-appearing brain tissues and can be used for normalization of corresponding parameters in tumor tissues for mitigating inter-subject variability due to errors in AIF. Normalized Ktrans and vb provided improved differentiation of HGG and LGG.
RATIONALE AND OBJECTIVES: To comprehensively evaluate robustness and variations of DCE-MRI derived generalized-tracer-kinetic-model (GTKM) parameters in healthy and tumor tissues and impact of normalization in mitigating these variations on application to glioma. MATERIALS (PATIENTS) AND METHODS: A retrospective study included pre-operative 31 high-grade-glioma(HGG), 22 low-grade-glioma(LGG) and 33 follow-up data from 10 patients a prospective study with 4 HGG subjects. Voxel-wise GTKM was fitted to DCE-MRI data to estimate Ktrans, ve, vb. Simulations were used to evaluate noise sensitivity. Variation of parameters with-respect-to arterial-input-function (AIF) variation and data length were studied. Normalization of parameters with-respect-to mean values in gray-matter (GM) and white-matter (WM) regions (GM-Type-2, WM-Type-2) and mean curves (GM-Type-1, WM-Type-1) were also evaluated. Co-efficient-of-variation(CoV), relative-percentage-error (RPE), Box-Whisker plots, bar graphs and t-test were used for comparison. RESULTS: GTKM was fitted well in all tissue regions. Ktrans and ve in contrast-enhancing (CE) has shown improved noise sensitivity in longer data. vb was reliable in all tissues. Mean AIF and C(t) peaks showed ~38% and ~35% variations. During simulation, normalizations have mitigated variations due to changes in AIF amplitude in Ktrans and vb.. ve was less sensitive to normalizations. CoV of Ktrans and vb has reduced ~70% after GM-Type-1 normalization and ~80% after GM-Type-2 normalization, respectively. GM-Type-1 (p = 0.003) and GM-Type-2 (p = 0.006) normalizations have significantly improved differentiation of HGG and LGG using Ktrans. CONCLUSION:Ktrans and vb can be reliably estimated in normal-appearing brain tissues and can be used for normalization of corresponding parameters in tumor tissues for mitigating inter-subject variability due to errors in AIF. Normalized Ktrans and vb provided improved differentiation of HGG and LGG.