Study Design
Total of 40 patients with spinal metastases from renal cell carcinomas (RCC) or prostate carcinomas (PC) were studied using DCE (Dynamic contrast-enhanced) MRI.
Objective
Our aim was to evaluate spinal metastases from RCC and PC to assess the sensitivity and specificity of perfusion parameters obtained by quantitative and semi-quantitative methods, which would allow for noninvasive discrimination between hypovascular and hypervascular lesions.
Summary of Background Data
Conventional MRI can be inconclusive in assessing diagnostically complex spinal lesions in cancer patients 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.
Methods
DCE perfusion parameters: vascular permeability (Ktrans), plasma volume (Vp), wash-in slope, and peak-enhancement were measured to assess their potential as discriminators of tumor vascularity. A Mann-Whitney test (at p≤0.01), was performed to quantify and compare significance of perfusion parameters between the two groups.
Results
Of the four perfusion parameters studied, Vp was observed to have the largest difference in mean (µ) between PC (µ=3.29/sec) and RCC metastases (µ=5.92/sec). This was followed by the peak-enhancement, Ktrans, and wash-in parameters. A Mann-Whitney test showed a significant difference between Vp values for PC and RCC lesions (p≤0.001). Similarly, peak-enhancement showed a significant difference between the two histologies (p≤0.001), as did Ktrans (p≤0.01). The receiver operating characteristic curve showed that Vp recorded the highest area under the curve (0.867).
Conclusion
Vp was shown to be the best discriminator between spinal metastases from PC and RCC with the mean Vp of RCC metastasis being 1.8 times that of the PC lesions, thus discriminating between hyper- and hypovascular metastases, which has important clinical implications.