Comparison of regional lung perfusion response on longitudinal MAA SPECT/CT in lung cancer patients treated with and without functional tissue-avoidance radiation therapy

• DOI: 10.1259/bjr.20190174
• Publication Date: 2019-07-31T10:47:29Z
• Authors: Hannah Mary T Thomas; Jing Zeng; Howard J Lee, Jr; Balu Krishna Sasi...; Paul E Kinahan; Robert S Miyaoka; Hubert J. Vesselle; Ramesh Rengan; Stephen R Bowen
• Keywords: Aged, 80 and over; Male; Tomography, Emission-Computed, Single-Photon; Lung Neoplasms; Perfusion Imaging; Radiotherapy Planning, Computer-Assisted; Dose-Response Relationship, Radiation; Middle Aged; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Humans; Female; Prospective Studies; Aged

The effect of functional lung avoidance planning on radiation dose-dependent changes in regional perfusion is unknown. We characterized dose-perfusion response longitudinal single photon emission computed tomography (SPECT)/CT two cohorts cancer patients treated with and without techniques.The study included 28 primary patients: 20 from interventional (NCT02773238) (FLARE-RT) eight observational (NCT01982123) (LUNG-RT) clinical trials. FLARE-RT treatment plans perfused dose constraints while LUNG-RT adhered to standards. Pre- 3 month post-treatment macro-aggregated albumin (MAA) SPECT/CT scans were rigidly co-registered four-dimensional CT scans. Tumour-subtracted was converted EQD2 sorted into 5 Gy bins. Mean percent change between pre/post-RT MAA-SPECT uptake (%ΔPERF), normalized total tumour-subtracted uptake, calculated each binned region. Perfusion frequency histograms analyzed. Dose-response data parameterized by sigmoid logistic functions estimate maximum increase (%ΔPERFmaxincrease), decrease (%ΔPERFmaxdecrease), midpoint (Dmid), dose-response slope (k).Differences MAA distribution shape time points observed 11/20 (55%) 2/8 (25%) (p < 0.05). >10% the 0-5 bin for 8/20 (%ΔPERFmaxincrease = 10-40%), which not any 0.03). Dmid at relative declined 50% trended higher compared (35 GyEQD2 vs 21 GyEQD2, p 0.09), k similar (3.1-3.2, 0.86).Functional may promote increased low regions select patients, though inter-patient variability remains high unbalanced cohorts. These preliminary findings form testable hypotheses that warrant subsequent validation larger within randomized or case-matched control investigations.This novel reports differences relationships receiving therapy those conventionally planned (LUNG-RT). Following further testing these effects patient populations, individualized estimation help refine future risk-adaptive strategies minimize function deficits toxicity incidence.