Three-dimensional surface display of dynamic pulmonary xenon-133 SPECT in patients with obstructive lung disease

To better perceive abnormal regional ventilation in patients with obstructive lung disease, a three-dimensional display was applied to dynamic pulmonary 133Xe SPECT.

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 reconstructing color-illuminated, surface-rendered three-dimensional images 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 133Xe retention was transparently visible through three-dimensional equilibrium image delineating lung contours. The three-dimensional equilibrium and WO3 images were created by a 25% threshold of the 133Xe maximal pixel activity (MPA) in equilibrium data. Besides, a three-dimensional WO3 image with a 18% threshold [mean + 2 s.d. ratios (%) of the MPA in WO3 data to that in equilibrium data in normal subjects] was used for assessing the presence of retention compared to normal lungs.

The 18% threshold three-dimensional WO3 image showed abnormal retention in obstructive diseases but not in restrictive diseases. The three-dimensional fusion display provided an overview of localized retention in obstructive diseases and enhanced the perception of their spatial relationships and extent compared to those on multislice tomograms. The extent of retention correlated well with %FEV1 (r = 0.813) and 133Xe clearance-time (T(1/2)) (r = 0.912).

This topographic modality for 133Xe SPECT is helpful for the better perception of anatomic distributions of 133Xe retention and interstudy comparisons of ventilation abnormality in patients with obstructive disease.