Semiquantification and classification of local pulmonary function by V/Q single photon emission computed tomography in patients with non-small cell lung cancer: potential indication for radiotherapy planning.
BACKGROUND
Perfusion (Q) single photon emission computed tomography (SPECT) has been used to divert dose away from higher-functioning lung during radiation therapy (RT) planning. This study aimed to (1) study regional lung function through coregistered pulmonary ventilation/perfusion (V/Q)-SPECT-CT and (2) classify these defects for its potential value in radiation planning in patients with non-small cell lung cancer (NSCLC).


METHODS
Patients with stages I to III NSCLC requiring radiation-based therapy were eligible for this prospective study. V/Q-SPECT performed within 2 weeks before the start of radiation was interpreted by nuclear medicine physicians and then measured by a semiquantitative score. The potential mechanism of V and Q defects was analyzed; the potential impact of V/Q-SPECT over Q-SPECT alone was completed through classified applications (high-dose RT versus RT avoidance) during planning.


RESULTS
Images of 51 consecutive patients were analyzed. The V and Q defects were matched, reverse mismatched (V defect > Q defect), and mismatched (Q defect > V defect) in 61, 31, and 8% of patients, respectively. Tumor was the leading cause of the defects of ipsilateral lung in 73% of patients. The defect scores of the ipsilateral lung were greater in patients with central primaries than those with peripheral primaries for both V-SPECT (2.3 ± 1.1 versus 1.5 ± 0.8, p = 0.017) and Q-SPECT (2.2 ± 0.8 versus 1.4 ± 0.6, p = 0.000). The patients with chronic obstructive pulmonary disease had greater defect scores in contralateral lung for both V-SPECT (1.5 ± 0.7 versus 1.0 ± 0.8, p = 0.006) and Q-SPECT (1.4 ± 0.6 versus 1.0 ± 0.4, p = 0.010). On assessing the potential value of SPECT on RT plan, 39% of patients could have their RT plan when applying V/Q-SPECT rather than Q-SPECT alone.


CONCLUSIONS
V/Q-SPECT provides a more comprehensive functional assessment, may provide additional value over Q-SPECT alone in assessing local pulmonary function, and guide RT plan decisions in patients with NSCLC.
Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, USA.
Shuanghu Tiger
ST
Yuan
Kirk A
KA
Frey
Milton D
MD
Gross
James A
JA
Hayman
Doug
D
Arenberg
Jeffrey L
JL
Curtis
Xu-Wei
XW
Cai
Nithya
N
Ramnath
Gregory P
GP
Kalemkerian
Randall K
RK
Ten Haken
Avraham
A
Eisbruch
Feng-Ming Spring
FM
Kong
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000145:classification* / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification* / Q000000981:diagnostic imaging / Q000532:radiotherapy; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted; D012129:Respiratory Function Tests; D015899:Tomography, Emission-Computed, Single-Photon