Comparison of Single Photon Emission Computed Tomography (SPECT) and implantable Doppler in the monitoring of a vascularised fibular free flap for reconstruction of the mandible.

Monitoring of microvascular free flaps is an influencing factor in the success or failure of the treatment. In this study, we aim to compare the accuracy of implantable Doppler and scintigraphy in the monitoring of a vascularised buried fibular graft for reconstruction of the mandible. In a prospective cohort study, an implantable Doppler was placed intraoperatively, and Single Photon Emission Computed Tomography (SPECT) was taken in patients when abnormal blood flow was detected via the implantable Doppler or 48 hours after operations in patients with normal signals on the Doppler. The flaps were explored if patients did not have regular signals via implantable Doppler or if SPECT revealed impaired perfusion. The number of true- and false-positive cases and true- and false-negative cases were documented. Positive predictive value (PPV) and negative predictive value (NPV) were calculated. Eighteen (29%) of 62 patients underwent explorative surgery. The sensitivity of SPECT was 38.88%, and specificity was 97.72%. In SPECT, PPV was 87.50% and NPV 79.62%. The sensitivity of the implantable Doppler was 72.22%, and specificity was 93.08%. In assessment with the implantable Doppler, PPV was 81.25% and NPV 93.18%. It seems that SPECT and the implantable Doppler had sufficient specificity in the monitoring of a buried fibular graft. However, SPECT had a lower sensitivity than the implantable Doppler.