Preliminary application of dynamic pulmonary xenon-133 single-photon emission tomography in the evaluation of patients with pulmonary emphysema for thoracoscopic lung volume reduction surgery

Abstract.

Dynamic pulmonary xenon-133 single-photon emission tomography (SPET) with three-dimensional (3D) displays was preliminarily applied to select resection targets for thoracoscopic lung volume reduction surgery (LVRS) and to assess regional ventilatory changes following surgery. Dynamic SPET was performed using a triple-detector SPET system in 14 patients with pulmonary emphysema before and after LVRS. After reconstructing colour-illuminated, surface-rendered 3D images of equilibrium (EQ) and 3-min washout (WO₃), a single 3D fusion display was created from these two different time-course image sets, in which the 3D WO₃ image indicating ¹³³Xe retention was visible through the overlying 3D EQ image delineating lung contours. Volumetric extent of retention on this display was quantified by a ¹³³Xe retention index, defined as the ratio (%) of total pixel numbers of segmented 3-min WO data to those of EQ data. ¹³³Xe SPET and appropriately thresholded 3D displays efficiently localized a total of 36 retention sites; 19 (52.7%) of these sites were not localized by CT because they were within the widely or homogeneously spreading non-bullous emphysematous lung tissues. The 3D displays enhanced the perception of anatomical configurations and the extent of ¹³³Xe retention compared with multislice tomograms. Postoperatively, 3D fusion display visualized the details of regional changes in retention, and changes in the retention index on the 3D display with a standardized threshold correlated well with changes in ¹³³Xe clearance time (T _1/2) and %FEV₁ (r = 0.881 and 0.856, respectively; P<0.0001). This preliminary study indicates that ¹³³Xe SPET and appropriately thresholded, topographic 3D displays are of potential use in selecting resection targets for LVRS, and in evaluating the treatment effects on regional ventilation.