Segmental mean transit times of 99m technetium within central vascular space in liver cirrhosis

Mean transit time (MTT) through a given vascular space is closely related to the effective blood volume in this compartment. Central vascular blood volume in liver cirrhosis is believed to be reduced, but more precise data on the location of the underfilled vascular area are lacking. 99mTechnetium first-pass angiography was performed in 15 cirrhotic patients and in 10 age-matched normals. The method of segmental analysis of MTT was validated by performing an analog study in a plastic tubing/chamber system. The mean tracer sojourn in the central circulation was described in cirrhotic patients (10.25 +/- 2.17 s vs 12.92 +/- 2.88 s; p less than 0.05); however, this finding was not observed beyond cardiopulmonary circulation (MTT between right and left heart chambers). Segmental comparative analysis between cirrhotics and normals revealed significant MTT differences in two vascular subcompartments, i.e. right chamber-pulmonary artery, and within the lung vascular bed. Analysis of time activity lung curves in patients with cirrhosis disclosed a shorter time to peak and more rapid washout of the tracer from this area, without any change in curve symmetry as compared to normals. Ascites had no apparent impact on MTT rate, and cirrhotics with most advanced disease (grade C Child-Pugh) had longer MTT through the cardiopulmonary circulation as compared to combined groups A & B (7.32 +/- 0.13 s vs 6.03 +/- 1.23 s; p less than 0.05). Our data provide further evidence for contraction of the cardiopulmonary vascular space in liver cirrhosis.