Different kinetics of lung clearance of technetium-99m labelled diethylene triamine penta-acetic acid in patients with sarcoidosis and smokers.
The rate of clearance from the lungs of inhaled technetium-99m labelled diethylene triamine penta-acetic acid (99mTc-DTPA) is often increased in interstitial lung disease as well as in smoking. In smokers a bi-exponential clearance course of 99mTc-DTPA when measured over 3 h has previously been shown. This study was performed to compare the kinetics of clearance of 99mTc-DTPA, measured for 3 h, in sarcoid patients and healthy smokers. Forty-one never-smoking patients with sarcoidosis and radiological signs of intrathoracic disease were studied. The results were compared with those of 16 healthy current smokers and of 14 healthy never-smokers reported previously. A mono-exponential clearance equation described the clearance in 22 of the sarcoid patients and all normal never-smokers, but with a shorter average tracer half-life in the patients (P < 0.05). In 19 patients and all smokers a bi-exponential equation gave a significantly better curve fit. The rate of clearance of the slow component was higher in patients with sarcoidosis than in smokers (P < 0.05). The fraction of the tracer cleared by the fast clearance component was smaller in patients with sarcoidosis than in smokers (P < 0.01). Differences in kinetics of clearance of 99mTc-DTPA in sarcoidosis and smoking could thus be demonstrated, suggesting that the abnormal clearance is caused by diverging pathophysiological mechanisms.
Department of Lung Medicine, University Hospital, Lund, Sweden.
I
I
Brådvik
P
P
Wollmer
E
E
Evander
H
H
Lárusdóttir
B
B
Blom-Bülow
B
B
Jonson
D000328:Adult; D005260:Female; D006207:Half-Life; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D011877:Radionuclide Imaging; D017565:Sarcoidosis, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012907:Smoking / Q000503:physiopathology*; D013147:Spirometry; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics; D013997:Time Factors
D016284:Technetium Tc 99m Pentetate