Comparison of Cerebral Blood Volume and Plasma Volume in Untreated Intracranial Tumors

PURPOSE: Plasma volume and blood volume are imaging-derived parameters that are often used to evaluation intracranial tumors. Physiologically, these parameters are directly related, but their two different methods of measurements, T1-dynamic contrast enhanced (DCE)- and T2-dynamic susceptibility contrast (DSC)-MR utilize different model assumptions and approaches. This poses the question of whether the interchangeable use of T1-DCE-MRI derived fractionated plasma volume (vp) and relative cerebral blood volume (rCBV) assessed using DSC-MRI, particularly in glioblastoma, is reliable, and if this relationship can be generalized to other types of brain tumors. Our goal was to examine the hypothetical correlation between these parameters in three most common intracranial tumor types. METHODS: Twenty-four newly diagnosed, treatment naïve brain tumor patients, who had undergone DCE- and DSC-MRI, were classified in three histologically proven groups: glioblastoma (n = 7), meningioma (n = 9), and intraparenchymal metastases (n = 8). The rCBV was obtained from DSC after normalization with the normal-appearing anatomically symmetrical contralateral white matter. Correlations between these parameters were evaluated using Pearson (r), Spearman's (ρ) and Kendall’s tau-b (τ(B)) rank correlation coefficient. RESULTS: The Pearson, Spearman and Kendall’s correlation between vp with rCBV were r = 0.193, ρ = 0.253 and τ(B) = 0.33 (p-(Pearson) = 0.326, p-(Spearman) = 0.814 and p-(Kendall) = 0.823) in glioblastoma, r = -0.007, ρ = 0.051 and τ(B) = 0.135 (p-(Pearson) = 0.970, p-(Spearman) = 0.765 and p-(Kendall) = 0.358) in meningiomas, and r = 0.289, ρ = 0.228 and τ(B) = 0.239 (p-(Pearson) = 0.109, p-(Spearman) = 0.210 and p-(Kendall) = 0.095) in metastasis. CONCLUSION: Results indicate that no correlation exists between vp with rCBV in glioblastomas, meningiomas and intraparenchymal metastatic lesions. Consequently, these parameters, as calculated in this study, should not be used interchangeably in either research or clinical practice.