Purpose: We ascertained the difference in the level of pulmonary hilar (PH) gallium-67 (Ga-67) uptake in autoimmune pancreatitis (AIP) patients between the active (before corticosteroid therapy) and remittent (after 4 weeks of corticosteroid therapy) phases using a semiquantitative measurement method based on single photon emission computed tomography (SPECT) with integrated low-dose computed tomography (CT).
Materials and methods: Ga-67 planar scans and SPECT were performed in 11 AIP patients before and after 4 weeks of corticosteroid therapy. A region of interest (ROI) was drawn over the bilateral pulmonary hilum and the liver, and average counts of the pulmonary hilum and liver were calculated. The average counts of the pulmonary hilum divided by those of the liver gave the pulmonary hilum/liver ratio (H/L).
Results: A significant difference was observed in the H/L between active and remittent phases. H/L in the active phase was 1.03±0.32 and that in the remittent phase was 0.58±0.25 (t-test, P=0.0016).
Conclusions: PH Ga-67 uptake in patients with active AIP was semiquantitatively higher than that in those with remittent AIP. Hence, this may be a useful finding for an early diagnosis, estimating the effectiveness of corticosteroid therapy, and following up patients with this disease.