An improved mathematical approach for the assessment of the medial thickness of pulmonary arteries.

Medial hypertrophy of pulmonary arteries is caused by different acute and chronic diseases complicated by pulmonary hypertension and malformations of the lung. Thus the precise assessment of external radius and relative medial thickness are of importance for clinical and experimental pathology. Different concepts have been proposed to solve this problem. Wall thickness methods which can be applied to obliquely cut arteries suffer from the disadvantage that they require prior injection of vessels. Planimetric methods can be applied to not injected vessels but they fail in assessing the medial thickness of obliquely cut arteries. We describe a mathematical approach which renders even obliquely cut and simultaneously not injected pulmonary arteries able to be assessed accurately for medial thickness and external vessel radius. This method combines the advantages of wall thickness and planimetric methods. This new method and the established wall thickness and planimetric methods were applied to 178 rat pulmonary arteries and 412 injected and 401 not injected human pulmonary arteries. The statistical analysis revealed a satisfying reproducibility (Coefficient of correlation: 0.70-0.90) of the new method. The data assessed by the new method are similar to those of the established methods. We conclude our new method to be a significant tool for the assessment of vessel parameters even in small specimens including only few not injected vessels.