Incremental value of 99mTc-MIBI single-photon emission computed tomography/computed tomography fusion imaging for the diagnosis of secondary hyperparathyroidism

Abstract

Purpose To assess the added value of 99mTc-MIBI single-photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging over dual-phase scintigraphy in the diagnosis of secondary hyperparathyroidism (SHPT). Methods This retrospective study included 23 patients with SHPT. The diagnostic efficacy of 99mTc-MIBI dual-phase scintigraphy and SPECT/CT fusion imaging was analyzed and compared based on the result of postoperative pathology and follow-up. To evaluate the diagnostic ability of 99mTc-MIBI dual-phase scintigraphy, the volume and radioactive count of parathyroid lesions were assessed using the region of interest method. Results A total of 79 hyperplastic parathyroid glands and two thyroid tissues were surgically removed from 23 SHPT patients and 13 normal parathyroid glands were preserved. 99mTc-MIBI SPECT/CT fusion imaging showed higher sensitivity and accuracy than 99mTc-MIBI dual-phase scintigraphy [sensitivity, 77.2% (61/79) vs 46.8% (37/79); accuracy, 80.4% (74/92) vs 54.3% (50/92), respectively], but comparable specificity [100% (13/13)). Among 61 positive lesions detected by 99mTc-MIBI SPECT/CT fusion imaging, 37 were dual-phase scintigraphy positive and 24 were dual-phase scintigraphy false negative. The radioactivity counts and radioactivity per unit volume in dual-phase scintigraphy positive were higher than that in dual-phase scintigraphy false negative (P < 0.05), but the volume of parathyroid lesions between the two groups had no significant difference (P > 0.05). Conclusion Compared with 99mTc-MIBI dual-phase scintigraphy, 99mTc-MIBI SPECT/CT fusion imaging has incremental value in the diagnosis of SHPT. The low uptake of MIBI in the whole gland and low MIBI uptake per unit volume are easy to cause dual-phase scintigraphy false negative.