99mtc-igg-lung scintigraphy in the assessment of pulmonary involvement in interstitial lung disease and its comparison with pulmonary function tests and high-resolution computed tomography: a preliminary study

Background: the discrimination of inactive inflammatory processes from the active form of the disease is of great importance in the management of interstitial lung disease (ild). objectives: the aim of this study was to determine the efficacy of 99mtc-igg scan for the detection of severity of disease compared to high-resolution computed tomography (hrct) and pulmonary function test (pft). patients and methods: eight known cases of ild including four cases of mustard gas (mg) intoxication and four patients with ild of unknown cause were included in this study. a population of six patients without lung disease was considered as the control group. the patients underwent pft and high-resolution computed tomography scan, followed by 99mtc-igg scan. they were followed up for one year. 99mtc-igg scan assessment of igg uptake was accomplished both qualitatively (subjectively) and semiquantitatively. results: all eight ild patients demonstrated a strong increase in 99mtc-igg uptake in the lungs, compared to the control patients. the 99mtc-igg scan scores were higher in the patient group (0.64[95% confidence interval (ci)=0.61-0.69])) than the control group (0.35 (0.35[95% ci=0.28-0.40]), (p<0.05)). in patients, a statistically significant positive correlation was detected between 99mtc-igg scan and hrct scores (spearman’s correlation coefficient = 0.92, p < 0.008). the 99mtc-human immunoglobulin (hig) scores were not significantly correlated with pft findings (including fvc, fev1, fev1/fvc), o2 saturation and age ( p values > 0.05). there were no significant correlations between 99mtc-igg score and hrct patterns including ground glass opacity, reticular fibrosis and honeycombing (p value > 0.05). conclusion: the present results confirmed that 99mtc-igg scan could be applied to detect the severity of pulmonary involvement, which was well correlated with hrct findings. this data also showed that the 99mtc-igg scan might be used as a complement to hrct in the functional evaluation of the clinical status in ild; however, further studies are recommended.