434 Determining the Utility of Early Phase [99mTc]Tc-MIBI Single-Photon Emission Computed Tomography with Contrast Enhanced Computerised tomography(SPECT/CECT) in Localisation of Parathyroid Adenomas for Surgical Planning

Aim To assess the utility of early phase [99mTc]Tc-MIBI SPECT scan compared to delayed phase [99mTc]Tc-MIBI SPECT and contrast-enhanced CT imaging in patients undergoing [99mTc]Tc-MIBI SPECT/CECT for localisation of parathyroid adenomas in preparation for parathyroidectomy surgery. Method A retrospective review of the images and reports of 52 consecutive patients who underwent nuclear medicine parathyroid studies was carried out. These were assessed to determine utility in interpretation of the early-phase SPECT compared to the delayed-phase SPECT and contrast-enhanced CT in detecting and localising parathyroid adenomas in preparation for parathyroidectomies by otorhinolaryngology surgeons. Results In 73% (n=38/52) of patients, the early-phase SPECT did not add any benefit to the localisation of the parathyroid adenoma. There were no patients who had any clear benefit by undergoing an early-phase SPECT. In 12% (n=6/52) of patients, there was no adenoma seen on any imaging modality. 12% (n=6/52) of patients were excluded because there was no contrast medium administered, and one patient had their study cancelled. Conclusions Overall, there was no evidence that the early-phase SPECT study added any benefit to the localisation of parathyroid adenomas, when performing [99mTc]Tc-MIBI SPECT/CECT scans. We plan to perform a prospective study with a larger sample size to draw more concrete conclusions and overcome the limitations of this retrospective study design. By not performing the early-phase SPECT study, there can be increased scanner time available to perform a greater number of imaging studies in a given timeframe, without having an impact on surgical planning or patient outcomes.