Comparison between MIBI-based radiopharmaceuticals for parathyroid scintigraphy: quantitative evaluation and...

Parathyroid scintigraphy is mandatory for the identification of hyperfunctioning parathyroid glands in hyperparathyroidism (HPT). The use of ^99mTc-methoxy-isobutyl-isonitrile (MIBI) as radiopharmaceutical for parathyroid scintigraphy is considered the most valid and useful considering its uptake mechanism. Several MIBI-based radiopharmaceuticals are commercially available (i.e., MediMIBI, TechneMIBI, Stamicis). They seem to have similar physico-chemical characteristics and the choice between them is based on commercial criteria, even though some differences in qualitative scintigraphic results have been appreciated. Aims of the study were: first, to compare the scintigraphic quantitative data of MediMIBI, TechneMIBI, and Stamicis, particularly in the view of a personalized medicine approach; second, to investigate the potential effect of clinical-laboratory data on image quality using one of these radiopharmaceuticals.

Patients with diagnosis of HPT, who underwent a parathyroid scintigraphy using one of the three MIBI-based radiopharmaceuticals between December 2018 and October 2020, have been retrospectively identified. Parameters derived from regions of interest (ROIs) drawn on three different sites were obtained: a reasonable parathyroid lesion detected, an area in the lateral neck considered as the background, and the hepatic dome as the site of MIBI physiological uptake. Laboratory and clinical data, such as serum calcium, PTH, vitamin D, and creatinine levels, as well as possible drug-mediated interferences were considered.

Among 250 patients included, 83 (33.2%) had the parathyroid scintigraphy using MediMIBI, 84 (33.6%) using TechneMIBI and 83 (33.2%) using Stamicis. The ROIs on the parathyroid uptake at early images, on the background, and on the hepatic dome were statistically different among the three groups (p < 0.05). No significant differences were found in the remaining semi-quantitative parameters among the three groups, not even considering clinical-laboratory data.

Some differences in semi-quantitative parameters emerged among MIBI-based radiopharmaceuticals for parathyroid scintigraphy. This might justify the different qualitative scintigraphic results obtained using one or another of the cited radiopharmaceuticals.