Impaired permeability in radiation-induced lung injury detected by technetium-99m-DTPA lung clearance.
This study evaluates the use of the 99mTc-DTPA aerosol lung clearance method to investigate radiation-induced lung changes in eight patients undergoing radiotherapy for lung or breast carcinoma. The sensitivity of the method was compared with chest radiography for detecting radiation-induced changes in the lung, regional alterations within (irradiated region) and outside (shielded region) the treatment ports, effect of irradiated lung volume, and dependence on time after radiotherapy.


METHODS
Serial DTPA lung clearance studies were performed before the first radiation treatment (baseline), then weekly during a 5- to 7-wk course, and up to 12 times post-therapy over periods of 56-574 days. The total activity deposited in the lungs for each study was approximately 150 microCi (approximately 5.6 MBq). DTPA clearance, expressed in terms of the biological half-time, t 1/2, was computed from the slopes of the least-squares fit regression lines of the time-activity curves for the first 10 min for irradiated and shielded lung regions.


RESULTS
Major findings include: (a) significant and early DTPA t 1/2 changes were observed in all patients during and after radiotherapy; (b) changes in DTPA t 1/2 values were observed in both irradiated and shielded lung regions in all patients suggesting a radiation-induced systemic reaction; (c) changes in DTPA t 1/2 values were correlated (p < 0.05) with the irradiated lung volumes; (d) significantly reduced DTPA t 1/2 values were observed in three patients who subsequently presented with clinical symptoms and/or radiographic changes consistent with radiation pneumonitis (t1/2 felt to 19% +/- 6% of baseline values, compared with 64% +/- 17% in the remaining patients [p < 0.01]); (e) the onset of decreased DTPA t 1/2 values in these three patients occurred 35-84 days before clinical symptoms and/or radiographic changes; and (f) DTPA t 1/2 tended to approach baseline values with time after radiotherapy, suggesting a long-term recovery in lung injury.


CONCLUSIONS
These observations show significant and early alterations in DTPA lung clearance during and after radiotherapy that may provide a sensitive assay to monitor changes in radiation-induced lung injury and may facilitate early therapeutic intervention.
Susskind
H
H
Clinical Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000, USA.
Weber
D A
DA
Lau
Y H
YH
Park
T L
TL
Atkins
H L
HL
Franceschi
D
D
Meek
A G
AG
Ivanovic
M
M
Wielopolski
L
L
D000336:Aerosols; D001943:Breast Neoplasms / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D017564:Radiation Pneumonitis / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D016284:Technetium Tc 99m Pentetate
D000336:Aerosols; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate