Detection of salivary aspiration using radionuclide salivagram SPECT/CT in patients with COPD exacerbation: a preliminary study

The aim of this prospective study was to assess the utility of radionuclide salivagram for detecting salivary aspiration in AECOPD patients and to evaluate the adding value of SPECT/CT to planar imaging.

52 consecutive AECOPD patients underwent radionuclide salivagram SPECT/CT and water swallow test between April 2012 and March 2014. All images were interpreted independently by two experienced nuclear medicine physicians. Final diagnosis was made by consensus of two readers. The radionuclide salivagram and water swallow test results were compared using kappa values. The relationship between radionuclide salivagram results and exacerbation frequency was evaluated with the Person χ² test.

Salivary aspiration was diagnosed by radionuclide salivagram in 17 of 52 patients. Aspiration into the right main bronchus and branch was seen in 8 patients, bilateral main bronchi in 6 patients, and left lung field in 3 patients. SPECT/CT provided more accurate information on the extent and location of salivary aspiration, in 11 cases, SPECT/CT demonstrated aspiration of pulmonary segment bronchus and the following areas. Moreover, SPECT/CT revealed salivary aspiration corresponding to aspiration pneumonia in 8 cases. There was general agreement between the radionuclide salivagram and water swallow test results (Kappa =0.712; 95% CI, 0.504-0.920; P<0.001). The incidence of frequent exacerbations was greater among subjects with positive salivagram than among those with negative salivagram results (RR =3.43; 95% CI, 1.90-6.19; P<0.001).

Radionuclide salivagram is an objective method for detecting salivary aspiration in AECOPD patients. Moreover, SPECT/CT can identify more precise location of salivary aspiration and suggest a possible role for saliva in the pathophysiology of aspiration pneumonia.