[Influence of experience on intra- and interindividual variability in assessing peripheral endothelial dysfunction with high resolution ultrasound].
The non-invasive evaluation of endothelial dysfunction with high-resolution ultrasound has become a widely accepted tool in determination of high-risk subjects for early atherosclerosis. Furthermore it is often used as intermediate outcome in intervention studies.


OBJECTIVE
We examined the influence of examiner experience on intra- and inter-individual variability in the measurement of flow-associated vasodilation (FAD) independent of automated analysis systems.


METHODS
FAD was measured on two occasions in 7 and 8 subjects respectively (mean age 32 +/- 3 years) by two investigators after different prior training procedures with a 13 MHz linear transducer (LA14A, ESAOTE Biomedica).


RESULTS
The intra-individual variability expressed as median absolute difference in the measurements of FAD was 1.1 % (range from 0.03 % to 3.2 %) for examiner one with an experience of more than 50 FAD measurements through former studies and 2.9 % (range from 1.6 % to 9.2 %) for examiner two with only 10 training examinations under supervision. By a further training period of two months, with an increase of examinations of additional 20 measurements by both examiners, the intra-observer variability could be dropped to 0.9 % (range from 0.03 % to 1.3 %) for examiner two (p = 0.0025) with no significant change for examiner one (median 0.6 % with a range from 0.14 % to 3.7 %). As expected, the inter-individual variability was not influenced by this further training (median 1.0 % with a range of 0.5 % to 3.6 % versus a median of 1.6 % with a range from 0.15 % to 7.5 %).


CONCLUSIONS
30 training measurements of FAD under supervision should be regarded as minimum requirement for valid determination of endothelial function. The reachable result for the intra-observer variability is thereby within the range of computed analysis systems.
Balletshofer
B M
BM
Abteilung für Endokrinologie und vaskuläre Medizin, Universität Tübingen. Bernd.Balletshofer@med.uni-tuebingen.de
Goebbel
S
S
Rittig
K
K
Lehn-Stefan
A
A
Renn
W
W
Enderle
M
M
Dietz
K
K
Häring
H U
HU
D000328:Adult; D001161:Arteriosclerosis / Q000000981:diagnostic imaging*; D001916:Brachial Artery / Q000000981:diagnostic imaging; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008297:Male; D015588:Observer Variation; D012016:Reference Values; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D014664:Vasodilation / Q000502:physiology*
Einfluss der Untersuchererfahrung auf intra- und interindividuelle Variabilität bei der Erfassung der peripheren Endothelfunktion mittels hochauflösendem Ultraschall.