[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.
Department of Nuclear Medicine, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, P.R.China.
Wen-Jie
WJ
Zhang
Rong
R
Zheng
Lu-Jun
LJ
Zhao
Lu-Hua
LH
Wang
Sheng-Zu
SZ
Chen
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