ABSTRACT
Background: To evaluate computed tomography [CT] and magnetic resonance imaging [MRI] fusion images for delineating gross tumor volume [GTV] in three-dimensional conformal radiotherapy [3D-CRT] of nasophanrygeal carcinoma [NPC], and compare treatment outcomes between CT- and CT+MRI-based targets
Materials and Methods: A total of 120 NPC patients treated with 3D-CRT were included, in which, 60 each were treated with CT-based and 60 with CT+MRI fusion targets. We explored the clinical application of CT+MRI fusion targets and compared the 1-, 3-, and 5-year survival and relapse rates between both targets
Results: The clinical characteristics and treatment factors were well balanced. The differences in public volume using CT alone in the CT+MRI [Group A] and the CT arm [Group B] were not significant [33.6+/-2.18 vs. 34.3+/-2.98, P > 0.05]. The public volumes of GTV in the two arms were 49.48+/-2.46 cm[3] and 33.6+/-2.18 cm[3] respectively [P < 0.05]. CT+MR fusion images did not influence the one-, three-, and 5-year survival rates [100% vs. 98.3%, 85.0% vs. 81.2%, and 73.3% vs. 68.3%, respectively]. The three- and 5-year out-of-field progression was reduced in the CT+MRI arm. However, only the difference in 3-year out-of-field relapse rate was significant [3.3% vs. 13.3%; P < 0.05]. The incidence of acute toxicities was similar between groups
Conclusion: The variability in GTV delineation in NPC was ascribed to intermodality and not interobserver variability. CT+MR fusion images likely reduced the 3-year out-of-field relapse rate