Spatially resolved regression analysis of pre-treatment FDG, FLT and Cu-ATSM PET from post-treatment FDG PET: an exploratory study.
OBJECTIVE
To quantify associations between pre-radiotherapy and post-radiotherapy PET parameters via spatially resolved regression.


METHODS
Ten canine sinonasal cancer patients underwent PET/CT scans of [(18)F]FDG (FDG(pre)), [(18)F]FLT (FLT(pre)), and [(61)Cu]Cu-ATSM (Cu-ATSM(pre)). Following radiotherapy regimens of 50 Gy in 10 fractions, veterinary patients underwent FDG PET/CT scans at 3 months (FDG(post)). Regression of standardized uptake values in baseline FDG(pre), FLT(pre) and Cu-ATSM(pre) tumour voxels to those in FDG(post) images was performed for linear, log-linear, generalized-linear and mixed-fit linear models. Goodness-of-fit in regression coefficients was assessed by R(2). Hypothesis testing of coefficients over the patient population was performed.


RESULTS
Multivariate linear model fits of FDG(pre) to FDG(post) were significantly positive over the population (FDG(post) ~ 0.17 · FDG(pre), p = 0.03), and classified slopes of RECIST non-responders and responders to be different (0.37 vs. 0.07, p = 0.01). Generalized-linear model fits related FDG(pre) to FDG(post) by a linear power law (FDG(post) ~ FDG(pre)(0.93),p<0.001). Univariate mixture model fits of FDG(pre) improved R(2) from 0.17 to 0.52. Neither baseline FLT PET nor Cu-ATSM PET uptake contributed statistically significant multivariate regression coefficients.


CONCLUSIONS
Spatially resolved regression analysis indicates that pre-treatment FDG PET uptake is most strongly associated with three-month post-treatment FDG PET uptake in this patient population, though associations are histopathology-dependent.
University of Wisconsin School of Medicine and Public Health, Madison, WI, USA. srbowen@uw.edu
Stephen R
SR
Bowen
Richard J
RJ
Chappell
Søren M
SM
Bentzen
Michael A
MA
Deveau
Lisa J
LJ
Forrest
Robert
R
Jeraj
D000818:Animals; D056831:Coordination Complexes; D003301:Copper Radioisotopes; D015224:Dideoxynucleosides; D004283:Dog Diseases / Q000000981:diagnostic imaging; D004285:Dogs; D019788:Fluorodeoxyglucose F18; D064847:Multimodal Imaging; D009669:Nose Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000662:veterinary; D009942:Organometallic Compounds; D010255:Paranasal Sinus Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000662:veterinary; D049268:Positron-Emission Tomography; D012044:Regression Analysis; D013882:Thiosemicarbazones; D014057:Tomography, X-Ray Computed
D056831:Coordination Complexes; D003301:Copper Radioisotopes; D015224:Dideoxynucleosides; D009942:Organometallic Compounds; D013882:Thiosemicarbazones; C089548:copper (II) diacetyl-di(N(4)-methylthiosemicarbazone); D019788:Fluorodeoxyglucose F18