| Objective To compare the primary tumor volume measured by FDG PET and MRI/CT in nasopharyngeal carcinoma and determine the optimal method for target volume delineation of nasopharyngeal carcinoma. Methods From Jan.2012 to Jan.2014, 50 patients with pathological diagnosed NPC were enrolled. The primary tumor volumes derived from the four methods, GTVMRI/CT,GTVPET2.5(autocontouring with the threshold of SUV ≥ 2.5), GTVPET40%(autocontouring with the threshold of ≥ 40% of SUVmax), GTVPET50%(autocontouring with the threshold of ≥ 40% of SUVmax) were compared with paired t test. Linear regression analysis was used to analyze the correlation coefficients between the MRI/CT and PET-derived tumor volumes.Results GTVMRI/CT,GTVPET2.5,GTVPET40%,GTVPET50%was 23.50±15.44cm3,30.72±17.72cm3, 23.41±15.08cm3, 19.12±13.26cm3, respectively. GTVPET2.5 was significantly larger than GTVPET40% and GTVMRI/CT (P<0.05), GTVPET40% was significantly larger than GTVPET50% (P<0.05),GTVPET50%was significantly smaller than GTVMRI/CT(P<0.05),and no significant difference was noted between GTVMRI/CT and GTVPET40% (P>0.05).The correlation of GTVMRI/CT and GTVPET2.5,GTVPET40%, GTVPET50%was good(r=0.978, 0.991, 0.990, P<0.05). Conclusion The threshold of ≥ 40% of SUVmax can be used for target volume delineation of nasopharyngeal carcinoma. |
