How to measure vessel caliber in microsurgery and super-microsurgery? Metrological study of three methods applicable in clinical practice.

[INTRODUCTION] The microsurgical literature reports the vascular calibers of the vessels studied even though the method of measurement of these vessels is very rarely reported.

[MATERIAL AND METHOD] We performed a metrological study evaluating three methods to measure the external calibers of catheters corresponding to microsurgical and super-microsurgical vessels (1.2 mm, 0.8 mm, and 0.6 mm). Six evaluators measured 15 catheters of three different hidden diameters by each of the three methods applicable in clinical practice: standard graduated ruler, Shinwa® micrometric ruler, and ImageJ® software from a photograph. Accuracy and reliability of the measurements were assessed by studying the inter- and intra-rater and inter-method coefficients (variants of the intra-class coefficient (ICC)) and analysis of the IC95% of the ICCs.

[RESULTS] Intra class correlation ICC "intra-rater" coefficient finds for the standard rule 0.81 [0.65-0.93], Shinwa® rule 0.86 [0.67-0.96], and for the ImageJ® software 0.97 [0.94-0.99]. The "Inter-rater" ICC shows respectively the coefficient 0.51 [0.23 and max 0.93], 0.87 [0.75-0.95], and 0.95 [0.89-0.98]. It appears that the graduated decimeter is the least reliable method of measurement, the Shinwa® ruler presents acceptable reliability but requires the purchase of equipment. The reliability of ImageJ® software is the best and appears to be the most reliable method.

[CONCLUSION] Our original study, with no equivalent in the scientific literature, demonstrates objectively the great accuracy and reliability of a method of measurement of vascular calibers in micro and super microsurgery using intraoperative photography and the use of free computer software.