Background. Preoperative imaging modalities to localise the parathyroid pathology have variable accuracy reported in various studies.1,2 Preoperative localisation results were correlated with surgical outcome to analyse the accuracy of ultrasound ( US), Sestamibi-Single Photon Emission Computed Tomography (SPECT), and four-Dimensional Computed Tomography (4D-CT), in primary hyperparathyroidism (pHPT).
Methods. All patients who had parathyroidectomy for pHPT in our institution in a period of two and half years were retrospectively analysed. Medical records, radiology, pathology and surgical records were systematically analysed. Results of localisation were correlated with surgical findings and histopathology diagnosis. Sensitivity and Positive Predictive Value (PPV) were calculated for each modality of localisation for comparison.
Results. 63 patients had surgery for pHPT during the specified period. 7 patients had hyperplasia on histopathology, rest all had confirmed adenoma. Only one patient had bilateral adenoma. 66% had Solitary adenomas in lower pole. 57, 62 and 16 patients had ultrasound scan, Sestamibi- SPECT, 4D-CT studies respectively, with respective sensitivity of 71.1%, 73.5% and 45.5%. PPV was 91.4%, 85.7%, and 71.4%, respectively.
32 patients had both US and Sestamibi-SPECT results concurred with combined sensitivity of 70.37% and PPV of 86.36%. 4D-CT scan localised adenoma in 2 patients when other modalities were negative. 5 patients had minimally invasive surgery. (39.3%) patients who had bilateral exploration had positive localisation. 10 patients did not show drop in intro-operative PTH. All 63 patients had normal calcium at 12 months follow-up with no recurrence of disease.
Conclusions. Accuracy of Ultrasound and Sestamibi-SPECT in localisation are similar (fig.1) and comparable to other reported studies.1,2,3,4 Accuracy may be improved with 4D-CT when other scans failed to localise.5 Further investigation is required to determine the role of 4D-CT scan. Choice of preoperative imaging depends on various patient factors. Good localisation studies assist the surgeons to choose appropriate surgical approach.