Does Preoperative Doppler Ultrasound and Resistive Index Measurement Predict the Solid Renal Masses Histopathology?

BACKGROUND: Renal masses have different histologic types and subtypes, aggressiveness and metastatic potential, depending on the changes in angiogenesis. OBJECTIVE: To differentiate between benign and malignant renal masses and predicate renal tumors histopathological subtypes by using non invasive methods (Doppler ultrasound and resistive index). PATIENTS AND METHODS: Sixty-eight patients with a renal mass prepared for surgical intervention were involved in this prospective study. Every patient was underwent Doppler ultrasonography by single operator. By gray and color Doppler ultrasound the site, location, dimensions, echogenicity and the vascularity of the renal mass were assessed. Then by spectral Doppler ultrasound specific vascular wave parameters from intra tumor vessels which include a Peak systolic velocity, end diastolic velocity and Resistive index was checked. All those patients underwent partial or radical nephrectomy and the histopathological result, were collected. RESULTS: It had been found that the mean RI in patients with clear RCC was 0.59 ± 0.09 and it was significantly higher than that of Wilms tumor (mean = 0.49 ± 0.05, (P. value = 0.029), and significantly higher than oncocytoma (0.42 ± 0.06) (P. value = 0.025). Patients with malignant renal mass had significantly higher mean RI than that of benign renal mass, 0.58±0.11vs 0.42±0.06,(P-Value =0.021) . The optimal cutoff point of RI was 0.47 which gives the higher sensitivity and specificity of 88.9% and 100% respectively with an accuracy of 94.5%, (PPV) was 100% and (NPV) was 90%. CONCLUSION: The usage of color spectral Doppler US parameter (Resistive index) is considered as an excellent predictor to differentiate between benign and malignant renal masses, but failed to differentiate and predicate the malignant renal tumors subtypes.