Aim: To evaluate diagnostic efficacy of advanced ultrasound (US) techniques in early and differential diagnosis of malignant tumors of the kidneys.
Material and methods: A total of 394 patients with renal mass lesions were studied. They had: renal cell carcinoma (n = 96), renal parenchyma pseudotumors (n = 22), lipoma (n = 48), angiomyolipoma (n = 19), renal abscess (n = 2), renal sinus lipomatosis (n = 1), parenchymal cysts (n = 205), retroperitoneal leiomyosarcoma with invasion in the kidney (n = 1). The following examinations were made: gray scale study with tissue harmonic imaging, panoramic scanning, US-angiography (color doppler imaging--CDI, power doppler imaging--PDI, 3D-reconstruction of the kidney vessels, 3D dynamic contrast enhanced angiography (DCEA) in the second harmonic mode with an echo-contrast agent levovist. Pulse Doppler with qualitative and quantitative evaluation of the doppler spectrum was used as an additional method. Verification of the diagnosis was made by conventional angiography, computer tomography, MR-tomography, histomorphological analysis after surgery in 91, 310, 6 and 88 patients, respectively.
Results: New US techniques allow differentiation of malignant tumors with renal lipomas and angiomyolipomas, focuses of inflammation, pseudotumors of the renal parenchyma and atypical renal cysts. CDI has revealed big pathologic vessels with arterio-venous and arterio-arterial shunts in renal cancer in 63.5% of the cases. PDI visualized a net of pathologically changed vessels in 74.8% of the cases. 3D-reconstruction in PDI was highly sensitive (90%) in visualization of neoplastic vessels. US-angiography was used for pre- and postoperative monitoring in 18 patients subjected to conservative renal surgery. In 23 patients DCEA with levovist allowed monitoring of all phases of contrast enhancement of renal vessels. Injection of contrast agent revealed tumor microvasculature in an early arterial phase (20-30 seconds).
Conclusion: US-angiographic techniques in diagnosis of renal cancer increases sensitivity and specificity of the US method compared to conventional B-mode US from 55 and 60% to 98 and 95%, positive and negative predictive value from 58 and 57% to 95 and 98%, respectively.