Diagnostic role of new Doppler index in assessment of renal artery stenosis.
BACKGROUND
Renal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension. Several non-invasive diagnostic methods for RAS have been used in hypertensive patients, such as color Doppler ultrasound (US). The aim of this study was to assess the sensitivity and specificity of a new renal Doppler US direct-method parameter: the renal-renal ratio (RRR), and compare with the sensitivity and specificity of direct-method conventional parameters: renal peak systolic velocity (RPSV) and renal aortic ratio (RAR), for the diagnosis of severe RAS.


METHODS
Our study group included 34 patients with severe arterial hypertension (21 males and 13 females), mean age 54 (+/- 8.92) years old consecutively evaluated by renal color Doppler ultrasound (US) for significant RAS diagnosis. All of them underwent digital subtraction arteriography (DSA). RAS was significant if a diameter reduction > 50% was found. The parameters measured were: RPSV, RAR and RRR. The RRR was defined as the ratio between RPSV at the proximal or mid segment of the renal artery and RPSV measured at the distal segment of the renal artery. The sensitivity and specificity cutoff for the new RRR was calculated and compared with the sensitivity and specificity of RPSV and RAR.


RESULTS
The accuracy of the direct method parameters for significant RAS were: RPSV >200 cm/s with 97% sensitivity, 72% specificity, 81% positive predictive value and 95% negative predictive value; RAR >3 with 77% sensitivity, 90% specificity, 90% positive predictive value and 76% negative predictive value. The optimal sensitivity and specificity cutoff for the new RRR was >2.7 with 97% sensitivity (p < 0.004) and 96% specificity (p < 0.02), with 97% positive predictive value and 97% negative predictive value.


CONCLUSIONS
The new RRR has improved specificity compared with the direct method conventional parameters (RPSV >200cm/s and RAR >3). Both RRR and RPSV show better sensitivity than RAR for the RAS diagnosis.
Chain
Sergio
S
Department of Cardiac and Vascular Ultrasonography, Centro Modelo de Cardiología and Centro Radiológico Mendez Collado, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina. sergchain@gmail.com
Luciardi
Hector
H
Feldman
Gabriela
G
Berman
Sofia
S
Herrera
Ramón N
RN
Ochoa
Javier
J
Muntaner
Juan
J
Escudero
Eduardo M
EM
Ronderos
Ricardo
R
D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D006978:Hypertension, Renovascular / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012078:Renal Artery Obstruction / Q000150:complications / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color