Parâmetros diretos do duplex scan no diagnóstico da estenose da artéria renal: estudo de validação e otimização dos pontos de corte

Abstract

To test the efficiency of the direct duplex scanning parameters in the diagnosis of renal artery stenosis (RAS), and verify whether or not the cut-off points recommended by medical literature are the most appropriate means to distinguish lesion severity. Prospective study, including 62 patients with RAS, submitted to a duplex ultrasound scan and selective arteriography. The peak systolic velocity (PSV) and the renal-aortic ratio (RAR) were measured. Statistical analysis included the ROC (receiver operating characteristic curve), unpaired students t-test, sensitivity, specificity, positive and negative predictive values and accuracy. The arteriography revealed RAS 0-59% in 31 arteries (24%); RAS 60-99% in 91 arteries (72%) and 5 occlusions (4%). ROC analysis demonstrated that the lesion detection efficiency of PSV and RAR were similar with areas below the curves of 0.96 and 0.95, respectively. Considering the cut-off points recommended by medical literature, PSV of 180 cm/sec presented a sensitivity of 100% and specificity of 81%, while the RAR of 3.5 presented a sensitivity of only 79%, with a specificity of 93%. These parameters were analyzed in conjunction (direct criteria) revealing a sensitivity of 79% and specificity of 97%. The optimized cut-off points were: PSV of 189 cm/sec and RAR of 2.6, demonstrating sensitivity and specificity rates of 100%, 87%, 96% and 87% respectively. The individual use of optimized peak systolic velocity (PSV) was the most efficient parameter in the detection and grading of RAS.