Role of perfusion CT in the evaluation of metastatic nodal tumor response after radiochemotherapy in head and neck cancer: preliminary findings

OBJECTIVE: To assess changes of CT perfusion parameters (ΔPCTp) of cervical lymph node metastases from head and neck cancer (HNC) before and after radiochemotherapy (RT-CT) and their association with nodal tumor persistence. PATIENTS AND METHODS: Eligibility criteria included HNC (Stage III-IV) candidates for RT-CT. Patients underwent perfusion CT (PCT) at baseline 3 weeks and 3 months after RT-CT. Blood volume (BV), blood flow (BF), mean transit time (MTT) and permeability surface (PS) were calculated. PET/CT examination was also performed at baseline and 3 months after treatment for metabolic assessment. RESULTS: Between July 2012 and May 2016, 27 patients were evaluated. Overall, only 3 patients (11%) experienced tumor persistence in the largest metastatic lymph node. A significant reduction of all PCTp values (p<0.0001), except MTT (from 6.3 to 5.7 s; p=0.089), was observed at 3 weeks post-RT-CT compared to baseline. All PCTp values including MTT were significantly lower at 3-month follow-up compared to baseline (p<0.05). Moreover, a statistical significant association was observed between nodal tumor persistence and high BF values (p=0.045) at 3 months after treatment that did not occur for the other parameters. CONCLUSIONS: Our preliminary findings show that all PCTp except MTT are significantly reduced after RT-CT. High BF values at 3 months post-RTCT are predictive of nodal tumor persistence.