Fundamental evaluation of quantitative measurement in single photon emission computed tomography and its clinical application in the lung

In order to make a fundamental assessment of the quantitative aspect of single photon emission computed tomography (SPECT), the factors influencing resolution of SPECT were evaluated using a phantom such as uniformity, smoothing, filter function, attenuation coefficients, numbers of projection, sampling time and distance between the detector and the phantom. As a clinical application of SPECT, the perfusion scan using 99mTc-MAA, tumor scan using 67Ga and measurements of pulmonary epithelial permeability using 99mTc-DTPA aerosol inhalation were performed. Localization of pulmonary segment was easier in pulmonary perfusion SPECT image compared with planar images. Ga SPECT image allowed evaluation of perihilar and mediastinal uptake of RI. The present study is the first in the field of assessment of alveolar epithelial permeability using 99mTc-DTPA aerosol inhalation SPECT, which is proved as the clinically applicable procedure. In the comparative study of alveolar epithelial permeability between a group of healthy subjects and a group of patients with diffuse interstitial pulmonary diseases using 99mTc-DTPA aerosol inhalation SPECT, the permeability was significantly accelerated in the patients group. (author)