There is no standard classification for quantifying the degree of internal carotid artery stenoses by means of Doppler sonography. Above all this requires a clear concept of how to define the degree of stenosis morphologically, which can be described as the local lumen narrowing or the residual lumen compared with the distal internal carotid artery. Because two different physical principles are applied, the correlation between morphologic findings and hemodynamic criteria assessed by Doppler sonography can be only rough. A classification into 5 categories is presented that is practicable also with Duplex scanning and which also takes Doppler frequency analysis into account.
The assessment of the renal arteries is particularly important in the detection of a renovascular cause of the arterial hypertension. The purpose of the present study was twofold: to evaluate the accuracy of duplex scanning in non-invasively diagnosing renal artery stenoses in hypertensive patients, and to determine the results of transluminal angioplasty of renal artery stenoses as assessed by duplex scanning. In 76 patients with arterial hyertension, 170 renal arteries (18 kidneys supplied by two renal arteries) were examined by both duplex scanning and angiography (DSA in intraarterial and intravenous technique, and conventional arteriography). Peak systolic and end-diastolic flow velocity parameters as well as the Pourcelot-index were determined in the proximal renal artery and compared with the indendently performed angiography. In 102 angiographically proven normal renal arteries, mean +/- SD peak systolic and end-diastolic velocity values were 84.7 +/- 13.9 cm/s and 31.2 +/- 7.8 cm/s, respectively, with a Pourcelot-index of 0.66 +/- 0.07. For detecting renal artery stenoses greater than 50%, duplex scanning had a sensitivity of 86%, and a specificity of 83% for a systolic peak velocity of 140 cm/s and more in the renal artery. In 13 patients with 14 stenosed renal arteries, duplex scanning and intraarterial DSA densitometry were performed before and after transluminal angioplasty of the renal artery stenoses. There was fairly good agreement between transstenotic peak systolic velocities and densitometrically determined degrees of stenosis in the renal artery (r = 0.84). These results show that duplex scanning is an accurate noninvasive diagnostic tool in detecting proximal renal artery stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)
In the management of patients with peripheral arterial occlusive disease the length and location of an arterial occlusion has an impact on the choice of the method of arterial reconstruction, i.e. percutaneous transluminal angioplasty or vascular surgery. The aim of this study was to determine the accuracy of colour-coded Doppler sonography (CDS) compared to conventional contrast arteriography in detecting the length and localisation of an occlusion in peripheral arteries. 100 legs of 94 patients (27 women, 44 to 82 years of age [mean 60.9 years] and 67 men, 21 to 78 years of age [mean 61.3 years]) with clinically suspected artery occlusion were examined prospectively with CDS before angiography and angioplasty. The exact localisation was correctly diagnosed by CDS in 95% with a high correlation (r = 0.95) of occlusion length between both methods. The sensitivity in detecting occlusions was 98% (positive predictive value 98%). It is concluded that colour-coded Doppler sonography can diagnose the length and location of an occlusion in peripheral arteries accurately and therefore can be used as a noninvasive method to select patients for further therapy management.
This article presents an introduction to some basic considerations for the evaluation of diagnostic tests and procedures. In order to determine the characteristics of a diagnostic procedure sensitivity and specificity are estimated from results of an evaluation study. The statement of confidence limits gives an idea of the safety of the estimates. Different scales of measurement and their respective distributions must be taken into consideration. Quite often sensitivity and specificity are dependent on various threshold values. ROC-curves can be used to study this dependence. In practice the interpretation of test results relies on the predictive value. The Bayes formula permits calculation of the predictive value depending on sensitivity, specificity and prevalence. This paper illustrates the application of statistical methods by analysing data of Doppler ultrasound studies.
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