A Comparison of Technegas and Xenon-133 Planar Lung Imaging in Subjects Referred for Ventilation Scintigraphy

Three blinded readers independently assessed the Xe-133 and Technegas images in separate reading sessions. Readers were blinded to all clinical information except a subject's screening chest X-ray. Xe-133 images were obtained per site-specific standard of care. Technegas images included a 6-view image set, and the primary endpoint was based on assessment of the subset of views that matched the Xe-133 image views. At the start of each case-read, a reader visually divided each lung into 3 regions of approximately equal size arranged craniocaudally (apical, mid, and basal), 6 regions in total, and then assessed each lung region for ventilation according to a three-point scale: 0=absent ventilation, 1=decreased ventilation, 2=normal ventilation. At the unplanned interim stage, PA between the Xe-133 scores and Technegas scores was tested for non-inferiority at one-sided alpha=0.0141, equivalent to the lower bound of the 97.18% confidence interval exceeding 60%.

Time frame: The median duration of Technegas imaging was 22 minutes. Blinded reader assessments of images ranged from <1 month to 16 months following the imaging (median 5 months).

Population: Full Analysis Set (FAS) consisting of subjects who completed all of the ventilation imaging on the study, and both sets of Xe-133 planar scans and the Technegas planar scans were of interpretable image quality according to site Investigators' assessment.

Three blinded readers independently assessed the Xe-133 and Technegas images in separate reading sessions. Readers were blinded to all clinical information except a subject's screening chest X-ray. Xe-133 images were obtained per site-specific standard of care. Technegas images included a 6-view image set. Two sequential reads were conducted of each subject's Technegas images. In the first read, only views that matched the Xe-133 image views were presented and read, and assessments based on the matched views were used in the primary outcome measure. Immediately following the commitment of those assessments, all Technegas image views were presented to the reader, and a second assessment of all the Technegas image views was made using the same ventilation scoring metric as described for the primary outcome measure. The estimation of PA and its analyses were also the same as for the primary outcome measure.

Time frame: The median duration of Technegas imaging was 22 minutes. Blinded reader assessments of images ranged from <1 month to 16 months following the imaging (median 5 months).

Population: Full Analysis Set (FAS) consisting of subjects who completed all of the ventilation imaging on the study, and both sets of Xe-133 planar scans and the Technegas planar scans were of interpretable image quality according to site Investigators' assessment.

By lung-region kappa statistics measuring inter-observer agreement between pairs of blinded readers for their ventilation scoring assessments within each of the three imaging groups: Xe-133, Technegas matched views, and Technegas all views. For each image set, a reader scored 6 regions of the lungs according to a three-point scale: 0=absent ventilation, 1=decreased ventilation, 2=normal ventilation. Kappa statistics for a pair of readers' assessments were derived from the frequencies of the cross-tabulation of the readers' ventilation scores by lung region. Kappa statistics are an index of inter-observer agreement corrected for chance with possible values ranging from -1 to 1, where 1 represents perfect agreement.

Time frame: The median duration of Technegas imaging was 22 minutes. Blinded reader assessments of images ranged from <1 month to 16 months following the imaging (median 5 months).

Population: Full Analysis Set (FAS)

Percent agreement (PA) measuring inter-observer agreement between pairs of blinded readers for their ventilation scoring assessments within each of the three imaging groups: Xe-133, Technegas matched views, and Technegas all views. For each image set, a reader scored 6 regions of the lungs according to a three-point scale: 0=absent ventilation, 1=decreased ventilation, 2=normal ventilation; agreement between a pair of readers' assessments was based on the agreement of their ventilation scores by subject and lung region.

Time frame: The median duration of Technegas imaging was 22 minutes. Blinded reader assessments of images ranged from <1 month to 16 months following the imaging (median 5 months).

Population: Full Analysis Set (FAS)