COMPARISON OF XE-133 WASHOUT AND SINGLE-BREATH IMAGING FOR THE DETECTION OF VENTILATION ABNORMALITIES

Abstract

The 133Xe ventilation studies of 115 patients were analyzed to determine the relative abilities of the single breath and washout phases to detect regional ventilation abnormalities. All 133Xe images were obtained in the posterior projection before 6 view perfusion studies with 99mTc human albumin microspheres. There were 275 regions with matching V-P [ventilation-perfusion] abnormalities in the patients. The washout portion of the study detected 258 of these regions (94%) and the single breath detected 175 (64%) (P < 0.01). The discrepancies were confined to regions with nonsegmental perfusion defects, where the single breath detected 139 matches and the washout 216. The discrimination ratio between normal areas and areas of obstructive lung disease improved from 2 to 1 after 1 min of washout to 30 to 1 after 5 min. The late phases of 133Xe washout are useful in detecting ventilation abnormalities, especially those associated with nonsegmental perfusion defects.