TY - JOUR
T1 - REPEATED POSITRON EMISSION TOMOGRAPHY-COMPUTED TOMOGRAPHY AND PERFUSION-COMPUTED TOMOGRAPHY IMAGING IN RECTAL CANCER: FLUORODEOXYGLUCOSE UPTAKE CORRESPONDS WITH TUMOR PERFUSION
AU - Janssen, Marco H. M.
AU - Aerts, Hugo J. W. L.
AU - Buijsen, Jeroen
AU - Lambin, Philippe
AU - Lammering, Guido
AU - Ollers, Michel C.
PY - 2012/2/1
Y1 - 2012/2/1
N2 - Purpose: The purpose of this study was to analyze both the intratumoral fluorodeoxyglucose (FDG) uptake and perfusion within rectal tumors before and after hypofractionated radiotherapy. Methods and Materials: Rectal cancer patients, referred for preoperative hypofractionated radiotherapy (RT), underwent FDG positron emission tomography (PET)-computed tomography (CT) and perfusion-CT (pCT) imaging before the start of hypofractionated RT and at the day of the last RT fraction. The pCT-images were analyzed using the extended Kety model, quantifying tumor perfusion with the pharmacokinetic parameters K(trans), v(e), and v(p). The mean and maximum FDG uptake based on the standardized uptake value (SUV) and transfer constant (K(trans)) within the tumor were correlated. Also, the tumor was subdivided into eight subregions and for each sub-region the mean and maximum SUVs and K(trans) values were assessed and correlated. Furthermore, the mean FDG uptake in voxels presenting with the lowest 25% of perfusion was compared with the FDG uptake in the voxels with the 25% highest perfusion. Results: The mean and maximum K(trans) values were positively correlated with the corresponding SUVs (rho = 0.596, p = 0.001 and rho = 0.779, p <0.001). Also, positive correlations were found for K(trans) values and SUVs within the subregions (mean, rho = 0.413, p <0.001; and max, rho = 0.540, p <0.001). The mean FDG uptake in the 25% highest-perfused tumor regions was significantly higher compared with the 25% lowest-perfused regions (10.6% +/- 5.1 %, p = 0.017). During hypofractionated radiotherapy, stable mean (p = 0.379) and maximum (p = 0.280) FDG uptake levels were found, whereas the mean (p = 0.040) and maximum (p = 0.003) K(trans) values were found to significantly increase. Conclusion: Highly perfused rectal tumors presented with higher FDG-uptake levels compared with relatively low perfused tumors. Also, intratumor regions with a high FDG uptake demonstrated with higher levels of perfusion than regions with a relatively low FDG-uptake. Early after hypofractionated RT, stable FDG uptake levels were found, whereas tumor perfusion was found to significantly increase.
AB - Purpose: The purpose of this study was to analyze both the intratumoral fluorodeoxyglucose (FDG) uptake and perfusion within rectal tumors before and after hypofractionated radiotherapy. Methods and Materials: Rectal cancer patients, referred for preoperative hypofractionated radiotherapy (RT), underwent FDG positron emission tomography (PET)-computed tomography (CT) and perfusion-CT (pCT) imaging before the start of hypofractionated RT and at the day of the last RT fraction. The pCT-images were analyzed using the extended Kety model, quantifying tumor perfusion with the pharmacokinetic parameters K(trans), v(e), and v(p). The mean and maximum FDG uptake based on the standardized uptake value (SUV) and transfer constant (K(trans)) within the tumor were correlated. Also, the tumor was subdivided into eight subregions and for each sub-region the mean and maximum SUVs and K(trans) values were assessed and correlated. Furthermore, the mean FDG uptake in voxels presenting with the lowest 25% of perfusion was compared with the FDG uptake in the voxels with the 25% highest perfusion. Results: The mean and maximum K(trans) values were positively correlated with the corresponding SUVs (rho = 0.596, p = 0.001 and rho = 0.779, p <0.001). Also, positive correlations were found for K(trans) values and SUVs within the subregions (mean, rho = 0.413, p <0.001; and max, rho = 0.540, p <0.001). The mean FDG uptake in the 25% highest-perfused tumor regions was significantly higher compared with the 25% lowest-perfused regions (10.6% +/- 5.1 %, p = 0.017). During hypofractionated radiotherapy, stable mean (p = 0.379) and maximum (p = 0.280) FDG uptake levels were found, whereas the mean (p = 0.040) and maximum (p = 0.003) K(trans) values were found to significantly increase. Conclusion: Highly perfused rectal tumors presented with higher FDG-uptake levels compared with relatively low perfused tumors. Also, intratumor regions with a high FDG uptake demonstrated with higher levels of perfusion than regions with a relatively low FDG-uptake. Early after hypofractionated RT, stable FDG uptake levels were found, whereas tumor perfusion was found to significantly increase.
KW - Perfusion-CT
KW - FDG-PET-CT
KW - Rectal cancer
KW - Hypofractionated radiotherapy
KW - Tumor perfusion
KW - FDG uptake
U2 - 10.1016/j.ijrobp.2010.10.029
DO - 10.1016/j.ijrobp.2010.10.029
M3 - Article
C2 - 21392896
SN - 0360-3016
VL - 82
SP - 849
EP - 855
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 2
ER -