Reliability of Ultrasound Diameter Measurements in Patients with a Small Asymptomatic Popliteal Artery Aneurysm: An Intra- and Inter-observer Agreement Study.

BACKGROUND: In this study the intra- and inter-observer variability of ultrasound measurements of the diameter of the popliteal artery were tested in a group of patients under surveillance for a small (diameter 10-20 mm), asymptomatic popliteal artery aneurysm (PAA). METHODS: From a group of patients under ultrasound surveillance for bilateral, asymptomatic PAAs, 13 consecutive patients agreed to participate in the study and provided informed consent. The maximum diameter of the popliteal arteries was assessed by a vascular technologist. The same assessment was repeated by a second vascular technologist, unaware of the results of the first measurement. After a week, this protocol was repeated. The intra- and inter-observer reliability of this measurement was calculated using intra-class correlation coefficients (ICCs) and Bland and Altman plots. RESULTS: Of the 10 patients with bilateral and three patients with unilateral PAA, 12 completed the 2 week protocol. A total of 86 measurements were analyzed. The mean diameter of the popliteal arteries was 13.5 ± 3.4 mm. The ICC for the intra-observer reliability of observer 1 was 0.96 (95% CI 0.92-0.99), p < .001 and of observer 2 was 0.98 (95% CI 0.95-0.99), p < .001. The ICC for the inter-observer reliability for the first measurements was 0.96 (95% CI 0.90-0.98), p < .001 and for the second measurements 0.97 (95% CI 0.94-0.99), p < .001. The Bland-Altman plots showed random error, while 95% of the variation was between 0.016 and 0.16, p > .47. The absolute magnitude of the systematic error of both observers was less than 0.135 mm (median 0.00). CONCLUSION: Ultrasound measurement of the maximum diameter of the popliteal artery is reproducible; hence, it is suitable for making a clinical treatment decision. Its use for surveillance of small, asymptomatic PAAs is justified.

Interobserver variation in duplex scanning of infrainguinal arterial bypass grafts.

OBJECTIVE: to determine the degree of interobserver variation of color-flow duplex scanning of infrainguinal arterial bypass grafts. METHODS: two experienced vascular technologists randomly assessed bypass grafts in 32 consecutive patients, using a color-flow duplex scan. In pre-defined segments the highest peak systolic velocity (PSV(max)) and end-diastolic velocity (EDV) were measured and a peak systolic velocity ratio (PSV ratio) was calculated. Results were analyzed as continuous variables (Bland and Altman plots and Intraclass Correlation Coefficient=ICC) and also as categorical data (weighted Kappa coefficient) for the PSV ratio 1-2.5, > or =2.5-4, > or =4.0. RESULTS: the ICC for the PSV(max), PSV ratio and EDV indicated "almost perfect" agreement for all three parameters. However, the Bland and Altman plots showed impressive interobserver variation for the higher values of all three parameters. For the PSV ratio categories a weighted kappa of 0.31 was calculated, indicating only fair agreement. Substantial variation was found for the categories with PSV ratios > or =2.5-4.0 and > or =4.0. CONCLUSION: though performing accurately for the lower values of the assessed parameters, duplex scanning shows considerable interobserver variation for the clinically significant higher values. Particularly in the PSV ratio interval > or =2.5-4.0, most relevant for clinical decision-making, the interobserver variability is unacceptable.

The value of the peak systolic velocity ratio in the assessment of the haemodynamic significance of subcritical iliac artery stenoses.

OBJECTIVES: iliac stenoses with a PSV ratio between 2.0 and 3.0 in patients with symptomatic arterial obstructive disease of the legs might be misinterpreted when compared with intra-arterial pressure measurements (IAPM). The aim of this study was to compare the value of the PSV ratio with IAPM as the reference standard in the assessment of the haemodynamic significance of subcritical iliac artery stenoses (iliac stenosis with PSV ratio between 1.5 and 3.5). DESIGN, PATIENTS AND METHODS: fifty-eight iliac tracts in 53 consecutive patients with symptomatic arterial obstructive disease of the legs with an isolated stenosis with PSV ratio between 1.5 and 3.5 were studied prospectively. The results of those iliac duplex scanning were compared to IAPM. Results a poor agreement was found between IAPM and PSV ratios. For the PSV ratios > or =2.0, 2.5 and 3.0 the sensitivities were 74%, 37% and 16%, respectively. The specificities were 70%, 90% and 95%, the positive predictive values 82%, 88% and 86%, respectively, and the negative predictive values 58%, 43% and 37%, respectively. CONCLUSION: the results of this study show that the PSV ratio parameter is not accurate enough to evaluate the haemodynamic significance of subcritical iliac artery stenoses.

[Consensus noninvasive diagnosis of peripheral arterial vascular diseases. Central Guidance Organization for Peer Review]. / Consensus non-invasieve diagnostiek van perifere arteriële vaatziekte. Centraal Begeleidingsorgaan voor de Intercolle-giale Toetsing (CBO).

The outcome is described of a 1993 consensus meeting regarding the role and value of functional non-invasive vascular investigations in the assessment of severity and localization of arterial obstructions and in the selection of a therapeutic strategy in patients with arterial obstructive disease of the lower extremities. Since symptoms and clinical investigation alone are unreliable in assessing the severity of peripheral arterial disease, complementary functional vascular examinations are needed. Measurement of the systolic blood pressures at ankle level by means of a sphygmomanometric method and a Doppler flowmeter allows reliable determination of the presence or absence of haemodynamically significant arterial obstructions. In the case of minor obstructions the sensitivity of ankle pressure measurements can be increased by examination during a period of hyperaemia, preferably induced by a treadmill walking test. In the case of unreliable ankle pressure measurements due to non-compressible arteries determination of the toe blood pressure is indicated. Segmental blood pressure measurements as well as Doppler analysis of the blood flow at various levels of the leg were not considered reliable enough for the localization of arterial obstructions, unless the obstructive disease is restricted to one single arterial segment. Accurate non-invasive localization of arterial obstructions and the determination of their haemodynamic severity are only possible by means of a combined echo-Doppler (duplex) examination of the arteries. Duplex examination can also be helpful in choosing between surgery and percutaneous transluminal angioplasty of localised stenoses and short occlusions.