Efficacy of Multislice CT Perfusion in Post Therapy Assessment of Nasopharyngeal Carcinoma – A Prospective Study in a Tertiary Care Institute.

Abstract

Objective: (1) To assess usefulness of pre therapy CT perfusion (CTp) in predicting post therapy response in biopsy confirmed case of Nasopharyngeal carcinoma (NPC). (2) To assess the efficacy of CTp in identifying local residue and radiation fibrosis in post therapy cases of NPC.

Methods: Prospective cohort study with 42 voluntary NPC patients in Department of Radiology for a period of 28 months, data acquired on multi-detector 128-slice CT scanner at baseline & after completion of treatment. Treatment outcome dichotomised as complete response, non-response (stable disease / progressive disease) & partial response using RECIST 1.1 criteria. All perfusion parameters compared at baseline and after treatment.

Results: According to 2018 AJCC Classification (8^th edition), patients were classified into various stages of NPC. With three deaths & one lost to follow up, cohort size reduced to 38, followed up for CTp at 5 to 6 weeks after therapy. Ten patients showed complete response (CR) taken as control, fourteen patients showed local residue (LR) & fourteen patients showed radiation fibrosis (RF). The pre and post therapy CTp parameters showed significant differences in blood flow BF (blood flow) (p=0.001), PS (permeability surface) (p=0.004) & Tumor size (TS) (p=0.001). Further group wise average reduction of tumor size (TS) analysis found that CR and RF group although statistically insignificant with each other, but significantly differed with LR group.

Conclusion: Results demonstrate CTp as reliable predictor of tumor response in NPC post therapy. Further, it empirically established difference of RF from LR taking CR group as control.