3-DIMENSIONAL SURFACE DISPLAY OF DYNAMIC PULMONARY XE-133 SPECT IN PATIENTS WITH OBSTRUCTIVE LUNG-DISEASE

To better perceive abnormal regional ventilation in patients with obst ructive lung disease, a three-dimensional display was applied to dynam ic pulmonary Xe-133 SPECT, Methods: Dynamic SPECT was performed using a triple-detector SPECT system in 30 patients with obstructive disease , 13 patients with restrictive disease and 7 normal subjects. After re constructing color-illuminated, surface-rendered three-dimensional ima ges of equilibrium and 3-min washout (WO3), a single three-dimensional fusion display was created from these two different time-course image sets in which a three-dimensional WO3 image indicating Xe-133 retenti on was transparently visible through three-dimensional equilibrium ima ge delineating lung contours. The three-dimensional equilibrium and WO 3 images were created by a 25% threshold of the Xe-133 maximal pixel a ctivity (MPA) in equilibrium data. Besides, a three-dimensional WO3 im age with a 18% threshold [mean + 2 s.d. ratios (%) of the MPA in WO3 d ata to that in equilibrium data in normal subjects] was used for asses sing the presence of retention compared to normal lungs. Results: The 18% threshold three-dimensional WO3 image showed abnormal retention in obstructive diseases but not in restrictive diseases. The three-dimen sional fusion display provided an overview of localized retention in o bstructive diseases and enhanced the perception of their spatial relat ionships and extent compared to those on multislice tomograms, The ext ent of retention correlated well with % FEV1 (r = 0.813) and Xe-133 cl earance-time (T-1/2) (r = 0.912), Conclusion: This topographic modalit y for Xe-133 SPECT is helpful for the better perception of anatomic di stributions of Xe-133 retention and inter-study comparisons of ventila tion abnormality in patients with obstructive disease.