[Perfusion study of the pulmonary hilar region by SPECT--normal cases]

Alveoli in the hilar region comprise the peripheral area containing daughter branches from subsegmental or one more divisional peripheral bronchi. Pulmonary perfusion in hilar region was examined by SPECT (single photon emission CT) in ten normal volunteers. ROI (region of interest) in the axial images were set in the hilar region, the upper, middle and lower lung fields with 10.8 mm thickness. Counts/one pixel (C/P) were calculated in these ROI. There was a tendency of C/P increase from upper to lower lung field. And there were no significant differences in C/P increase between hilar region and other axial fields. In the chronic obstructive pulmonary diseases, however, ventilation studies in the previous reports using Xe dynamic CT or PET (positron emission tomography) showed differences between outer region and hilar region. This method will be expected to evaluate the pulmonary perfusion not only in the whole lung but in different lung areas, including the hilar region in the chronic obstructive pulmonary diseases.