Comparison of Color Doppler Ultrasound with Digital Subtraction Angiography

Abstract

Objective: To compare the sensivity and specificity of color Doppler ultrasound (CDU) with digital subtraction angiography (DSA) or magnetic resonance angiography (MRA) in the evaluation of transplant renal artery stenosis (TRAS).
Methods: A retrospective study of 36 patients with suspected TRAS who underwent CDU at Siriraj Hospital between May 2001-December 2005 were investigated. Both intrarenal vessels and the transplant main renal artery examination were reviewed. TRAS was diagnosed if the peak systolic velocity (PSV) of the main renal artery is more than 150 cm/sec. The result of CDU was confirmed by DSA , MRA or clinical follow up. The Chi-square test was used to determine statistical analysis.
Results: 37 studies of CDU examinations (46.8%) of 77 cases were encountered in this study. 21 studies (56.8%) had diagnosis of TRAS by CDU (PSV ≥ 150 cm/sec) with a sensitivity of 100% and specificity of 80% by comparison to the results of DSA or MRA. Of 17 studies with TRAS, 12 studies had a prolonged acceleration time (AT) and 15 studies had a normal resistive index (RI) in the intrarenal arteries. Almost all patients in this study had no renal to iliac velocity ratio (RIR) measurement, however, the remainder of 3 cases with measurement showed no increased RIR ratio.
Conclusion: The criteria for detection of TRAS using the peak systolic velocity of the main renal artery more than 150 m/sec is sensitive and specific enough to be used as a screening test. Intrarenal vascular study using acceleration time can be used to confirm the diagnosis of severe TRAS but the resistive index is not helpful to evaluate TRAS.