COMPUTERIZED MORPHOMETRY OF THE PULMONARY VASCULATURE OVER A RANGE OFINTRAVASCULAR PRESSURES

Recent availability of computerized image analysis has fostered hope t hat barium injection and landmarking of pulmonary arteries would be un necessary for morphometric assessment when using this technique. We re asoned that if barium injection altered morphometric variables, it wou ld do so in a linear fashion correlating with incremental increases in injection pressure of the barium. The two goals of the present study were to determine whether barium injection into arteries affected morp hometric measurements and to determine whether incremental increases i n injection pressure correlated with alterations in morphometric measu rements in a linear fashion. Computerized image analysis was used to m easure the internal elastic lamina (IEL) and external elastic lamina ( EEL). Medial area (MA), luminal area (LA), percentage of medial thickn ess, IEL root MA, and idealized LA were calculated. Barium injection d id not alter morphometric variables in a linear fashion correlating wi th incremental increases in injection pressure of the barium except th e percentage of arteries that filled with barium. Maximum recruitment for pre-acinar arteries occurred at 40 mmHg pressure and 60 mmHg diste nding pressure for intra-acinar arteries. Incremental increases in inj ection pressure did not affect IEL, EEL, or calculated morphometric va riables. However, IEL, medial thickness, and MA were all smaller in in jected vessels than in uninjected vessels. IEL root MA and the ratio o f measured vs. idealized LA were both increased in injected lungs. We suspect that vascular injection selects for evaluation, a population o f smaller, thin-walled vessels, which in the uninjected lungs are coll apsed and hence excluded from analysis. (C) 1998 Wiley-Liss, Inc.