<prompt> The investigation of choice to evaluate IVC Renal Vein thrombosis in Renal Cell Ca is :IVPColor DopplerCT ScanUltra sound  <response>: Ans. is c i.e. CT scan Diagnosis of Renal Vein IVC thrombosisVenography Inferior vena cavogram selective renal venography is the most reliable and definitive diagnostic investigation for establishing the presence of thrombus. However its invasive and rarely used now a days.MRI - is the best non-invasive imaging modality for IVC and renal vein thrombosis.CT - is next best to MRI, with sensitivity and specificity as high as 92 and 100 Ref: Grainger, 7e, p 1523 Sutton writes - MR and CT are both highly accurate in the demonstration of venous invasion.Doppler - is able to detect the venous thrombosis as echogenic material in the venous lumen and absence of flow. But it has got its limitations and is thus inferior to CT MR.Also rememberCT is the imaging modality of choice for diagnosing and staging renal cells ca. 