Single photon emission computed tomography in the canine lung.

A whole body single photon emission computed tomographic system (SPECT) has been used to investigate canine pulmonary perfusion utilizing 99mTc-microspheres and has been compared to conventional radionuclide pulmonary perfusion studies. The SPECT data were reconstructed and displayed in 32 transverse, 16 sagittal, and 16 coronal plane sections, producing additional anatomical information on the pattern of pulmonary perfusion compared to that available with the conventional perfusion scan. The major bronchi, the major blood vessels, and the pulmonary hila are readily seen on the SPECT examination (confirmed anatomically) but are not easily identified on a conventional lung scan. Qualitative assessment of serial SPECT scans established that the distribution and relative concentration of infected radiopharmaceutical was consistent provided the studies had been performed with the animal in the same anatomical position. Changes in the dog's position resulted in a redistribution of radiopharmaceutical such that the most dependent lung contained the greatest concentration.