Magnetic resonance perfusion characteristics of hypervascular renal and hypovascular prostate spinal metastases: clinical utilities and implications.

Abstract

A total of 40 patients with spinal metastases from renal cell carcinomas (RCCs) or prostate carcinomas (PCs) were studied using DCE-MRI (dynamic contrast-enhanced magnetic resonance imaging). To evaluate spinal metastases from RCC and PC to assess the sensitivity and specificity of perfusion parameters obtained by quantitative and semiquantitative methods, which would allow for noninvasive discrimination between hypovascular and hypervascular lesions. Conventional MRI can be inconclusive in assessing diagnostically complex spinal lesions in patients with cancer in whom fibrosis, infarction, edema related to compression fractures, and infection may simulate malignant neoplasm. Conventional MRI is also of limited value in assessing tumor vascularity and identifying hypervascular tumors. DCE-MRI offers an advantage over conventional MRI in that it provides anatomical, physiological, and hemodynamic information about neoplastic lesions. DCE perfusion parameters: vascular permeability, plasma volume (V(p)), wash-in slope, and peak-enhancement parameter were measured to assess their potential as discriminators of tumor vascularity. A Mann-Whitney U test (at P ≤ 0.01), was performed to quantify and compare significance of perfusion parameters between the 2 groups. Of the 4 perfusion parameters studied, V(p) was observed to have the largest difference in mean (μ) between PC (μ = 3.29/s) and RCC metastases (μ = 5.92/s). This was followed by the peak-enhancement, vascular permeability, and wash-in parameters. A Mann-Whitney U test showed a significant difference between V(p) values for PC and RCC lesions (P ≤ 0.001). Similarly, peak-enhancement parameter showed a significant difference between the 2 histologies (P ≤ 0.001), as did vascular permeability (P ≤ 0.01). The receiver operating characteristic curve showed that V(p) recorded the highest area under the curve (0.867). V(p) was shown to be the best discriminator between spinal metastases from PC and RCC with the mean V(p) of RCC metastasis being 1.8 times that of the PC lesions, thus discriminating between hyper- and hypovascular metastases, which has important clinical implications.