The Usefulness of ^99mTc-Technegas Scintigraphy for Diagnosing Pulmonary Impairment Caused by Pulmonary Emphysema

X-ray computed tomography (CT) has been used for diagnosis of pulmonary emphysema because it can reveal the morphology of low attenuation areas. Recently, 99mTc-Technegas imaging, one of several types of scintigraphic techniques, has been used for ventilation scintigraphy. Technegas scintigraphy was performed on 15 patients with pulmonary emphysema, and we compared the extent and degree of abnormal findings on Technegas scintigraphy with the extent of low attenuation areas shown by CT. We classified the findings of Technegas imaging into three grades, from mild to severe, according to the extent of peripheral irregularity and central hot spot formation. We also classified the findings of CT as centrilobular emphysema into three grades from mild to severe according to the extent of low attention areas in the peripheral lung fields. In 5 cases, CT and Technegas assessment resulted in equivalent diagnoses. In eight cases, Technegas images showed more detailed findings than CT images. In the two remaining cases, which were diagnosed as panlobular emphysema on CT, Technegas images showed the severe stage. Technegas scintigraphy was useful for diagnostic assessment of pulmonary emphysema, especially for panlobular emphysema, which is difficult to distinguish from the normal lung condition by CT assessment.