Dynamic Surgeon-directed Imaging In The Preoperative Localization Of Patients With Primary Hyperparathyroidism
*Caitlin T Yeo, *Senthuran Tharmalingam, Janice L Pasieka
University of Calgary, Calgary, AB, Canada
OBJECTIVE(S): Preoperative imaging including Tc-99 sestamibi (MIBI) scans and ultrasonography play an important role in parathyroid localization in primary hyperparathyroidism (PHPT). It was observed that a significant number of MIBI scans were being read by the radiologist as non-localizing. However, when independently reviewed by the surgeon at time of consultation, the interpretation of the scan was read as localizing. The ability to perform real-time interpretation of both surgeon-performed bedside ultrasound (SUS) and MIBI scan appeared to improve preoperative localization. Therefore, the objective was to evaluate radiologist read MIBI scans (R-MIBI) compared to dynamic surgeon-directed imaging (DSDI) [a combination of the experienced surgeon's independent interpretation of the MIBI (S-MIBI) in conjunction with SUS]. METHODS: A retrospective review of all surgically treated PHPT patients from 2010 to 2019 was performed. Patients with increased risk of multi-gland disease were excluded. The DSDI, parathyroidectomy, and follow-up were all performed by the same surgeon. Patient demographics, biochemistry, R-MIBI, DSDI, operation, pathology, and follow-up results were collected. Localization rate, sensitivity, positive predictive value (PPV), and accuracy were calculated. RESULTS: 478 charts meeting criteria were reviewed. Mean age was 60 years. Single-gland disease was found in 83%. Overall, only 64% of R-MIBI scans were localizing, whereas DSDI localized 95% of the time. DSDI was superior to R-MIBI with 95% vs 61% sensitivity, 84% vs 87% PPV, and 80% vs 56% accuracy respectively. Analyzing single-gland disease only, there was an improvement in both DSDI and R-MIBI, however DSDI continued to be superior (97% vs 67% localization rate, 96% vs 66% sensitivity, 92% vs 95% PPV, 89% vs 64% accuracy). Significant factors that resulted in correct DSDI localization included younger age, higher pre-operative calcium, and larger gland size (1.20±2.22g vs 0.32±0.25g). CONCLUSIONS: The ability to perform dynamic imaging with real-time interpretation by the surgeon of both the bedside ultrasound and the S-MIBI drastically improves the preoperative localization rate when compared to the static reading of the MIBI scan by the radiologist. This underscores the importance of having all PHPT patients assessed by an experienced surgeon capable of performing DSDI, especially when the R-MIBI scan is non-localizing.
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