[Utility of SPECT lung perfusion scans in assessing early changes in pulmonary function of patients with lung cancer after radiotherapy].
OBJECTIVE
Radiation-induced lung injury is commonly following radiotherapy (RT)for tumors in,and around the thorax. Lung function is usually assessed by pulmonary function tests (PFTs), but RT-induced regional changes of pulmonary function cannot be accurately evaluated by PFTs. Lung perfusion scintigraphy compared with other radiographic methods can well assess the regional pulmonary physiological function,and 3-dimension conformal radiotherapy (3D-CRT) planning system can quantitatively calculate irradiation dosage. This study was to assess early changes in the pulmonary function of patients with lung cancer receiving thoracic 3D-CRT by lung perfusion scintigraphy.


METHODS
Nineteen patients receiving thoracic 3D-CRT for lung cancer were studied. Single photon emission computed tomography (SPECT) lung perfusion scan,and X-ray or CT scan before RT, and after 40-50 Gy radiation were performed. Pre-RT SPECT lung perfusion images were classified by comparing lung perfusion defect with area of radiological abnormality before RT. Grade 0: no lung perfusion defect in the area of radiological abnormality. Grade 1: the size of radiological abnormality is similar to the area of lung perfusion defect. Grade 2: the area of lung perfusion defect is bigger than that of radiological abnormality,and extend to 1 pulmonary lobe. Grade 3: the area of lung perfusion defect exceed 1 pulmonary lobe. The radiation field with more than 20 Gy was drawn as a region of interest (ROI). The proportion of radioactive count within this ROI to total lung count in one slice was calculated to assess changes in pulmonary function after RT. Student's t test was used for statistical analyses.


RESULTS
All patients had lung perfusion defect, 9 patients with grade 1 damage, 5 patients with grade 2 damage, and 5 patients with grade 3 damage. All tumors in the 19 patients were reduced with variant degree after 40-50 Gy radiation in CT or X-ray images. The mean radioactive proportions of ROI in 19 patients were (53.7+/-29.8)% before radiation,and (57.6+/-22.6)% during RT, the difference wasn't significant (P=0.280). The relatively decreased post-RT lung perfusion was observed in 6 patients, whereas the relatively increased post-RT lung perfusion was observed in 13 patients.


CONCLUSIONS
SPECT lung perfusion scans is a simple, convenient, and useful method for assessing pre-RT regional lung function,and monitoring the changes in regional lung function after irradiation.
Zhang
Wen-Jie
WJ
Department of Nuclear Medicine, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, P.R.China.
Zheng
Rong
R
Zhao
Lu-Jun
LJ
Wang
Lu-Hua
LH
Chen
Sheng-Zu
SZ
D000328:Adult; D000368:Aged; D018288:Carcinoma, Small Cell / Q000503:physiopathology / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000503:physiopathology / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000503:physiopathology* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D020266:Radiotherapy, Conformal; D011882:Radiotherapy, High-Energy / Q000009:adverse effects; D012129:Respiratory Function Tests; D015899:Tomography, Emission-Computed, Single-Photon