Semi-quantitative ventilation perfusion scintigraphy and single-photon emission tomography for evaluation of lung volume reduction surgery candidates: description and prediction of clinical outcome

Ventilation/perfusion scans with single-photon emission tomography (SPET) w ere reviewed to determine their usefulness in the evaluation of lung volume reduction surgery (LVRS) candidates, and as a predictor of outcome after s urgery. Fifty consecutive planar ventilation (Tc-99m-DTPA aerosol) and perf usion (Tc-99m-MAA) scans with perfusion SPET of patients evaluated for LVRS were retrospectively reviewed. Technical quality and the severity and exte nt of radiotracer defects in the upper and lower halves of the lungs were s cored from visual inspection of planar scans and SPET data separately. An e mphysema index (EI) (extent x severity) for the upper and lower halves of t he lung, and an EI ratio for upper to lower lung were calculated for both p lanar and SPET scans. The ratios were compared with post-LVRS outcomes, 3, 6 and 12 months after surgery. All perfusion and SPET images were technical ly adequate. Forty-six percent of ventilation scans were not technically ad equate due to central airway tracer deposition. Severity, extent, EI scores and EI ratios between perfusion and SPET were in good agreement (r = 0.52- 0.68). The mean perfusion EI ratio was significantly different between the 30 patients undergoing bi-apical LVRS and the 17 patients excluded from LVR S (3.3+/-1.8 versus 1.2+/-0.7; P<0.0001), in keeping with the anatomic dist ribution of emphysema by which patients were selected for surgery by comput ed tomography (CT), The perfusion EI ratio correlated moderately with the c hange in FEV1 at 3 months (r = 0.37, P = 0.04), 6 months (r = 0.36, P = 0.0 5), and 12 months (r = 0.42, P = 0.03), and the transition dyspnea index at 6 months (r = 0.48, P = 0.014) after LVRS, It is concluded that patients s elected to undergo LVRS have more severe and extensive apical perfusion def icits than patients not selected for LVRS, based on CT determination. SPET after aerosol V/Q imaging does nor add significantly to planar perfusion sc ans. Aerosol DTPA ventilation scans are not consistently useful. Perfusion lung scanning may be useful in selecting patients with successful outcomes after LVRS.