Detection and Characterization of Parathyroid Adenoma/Hyperplasia for Preoperative Localization: Comparison Between 11C-Methionine PET/CT and 99mTc-Sestamibi Scintigraphy

Chun, In Kook; Cheon, Gi Jeong; Paeng, Jin Chul; Kang, Keon Wook; Chung, June Key; Lee, Dong Soo

Abstract

PURPOSE
11C-Methionine PET/CT (Met-PET/CT) is a useful imaging method for detection of parathyroid adenoma; however, the reported detection rate has been variable. The current study was intended to investigate detection sensitivity and preoperative localization of parathyroid adenoma (PA) or parathyroid hyperplasia (PH) on Met-PET/CT compared with 99mTc-sestamibi (MIBI) scintigraphy in patients with primary hyperparathyroidism (HPT) or suspected PA.
METHODS
Met-PET/CT and MIBI scintigraphy images were reviewed by two nuclear medicine physicians unaware of pathologic results. Detection sensitivities and preoperative localization of detected parathyroid tissues into five predefined segments were evaluated by visual assessment and semiquantitative analysis with ratio of standardized uptake values (SUVR) between parathyroid tissue and normal lung as reference. Linear regression analysis with SUVR and serum parathyroid hormone (sPTH) was performed for characterization of PA or PH. Predicted PTH (pPTH) was calculated and compared with sPTH in PH and PA. Each pPTH was obtained for a calculated SUVR by using linear regression model from the result of previous linear regression analysis between SUVR and sPTH.
RESULTS
In 16 patients, detection sensitivities of Met-PET/CT and MIBI scintigraphy were 91.7 % (11/12) and 41.7 % (5/12) for PA and PH including both biopsy-confirmed and clinically-suspected cases, and 100 % (8/8) and 50 % (4/8) for pathologically confirmed PA and PH cases only, respectively. Met-PET/CT showed higher performance than MIBI scintigraphy in localization of parathyroid tissues; correct localization rate was 87.5 % (7/8) on Met-PET/CT and 50 % (4/8) on MIBI scintigraphy. In semi-quantitative analysis, SUVR was linearly associated with sPTH by linear regression analysis (sPTH=39.53xSUVR-89.84, p=0.0383). There was a borderline significant difference in pPTH between PH and PA (35.1 vs 204.7+/-164.0, p=0.052), while therewas no significant difference in sPTH between PH and PA (289 vs 230.4+/-160.4, p=0.305).
CONCLUSIONS
Met-PET/CT has a potential to be a useful diagnostic modality for preoperative detection and localization of parathyroid tissues with higher sensitivity than MIBI scintigraphy, and for characterization of PA or PH.