Adverse clinical events at the injection site are exceedingly rare following reported radiopharmaceutical extravasation in patients undergoing 99m Tc-MDP whole body bone scintigraphy: A 12-year experience.

Rationale: The deleterious effects of high-dose radiation on normal tissue are sometimes extrapolated to diagnostic (SPECT and PET) radiopharmaceutical extravasations (RPE). It has been hypothesized that diagnostic RPE can have gradually evolving local tissue injury and a potentially increased risk of local dermatologic or oncologic diseases over a longer period. However, data on clinical adverse events following diagnostic RPE is limited. Therefore, our primary aim was to study the occurrence of short-term and long-term clinical adverse events in patients who underwent 99m Tc-Methylene diphosphonate ( 99m Tc-MDP) whole-body bone scintigraphy (WBBS) with reported RPE. Methods: The records of 99m Tc-MDP WBBS performed from June 2010 to January 2022 were retrospectively examined for RPE documented in the scan reports. The clinical records of patients with a documented RPE were extensively reviewed for any related short-term adverse events (within two weeks of the WBBS - local symptoms, and care sought for local dermatologic or musculoskeletal issues), and long-term adverse events (until last follow-up - local deleterious effects, related consults for dermatology, plastic surgery, oncology or orthopedics). Results: Retrospective review of the records of 31,679 99m Tc-MDP WBBS showed RPE documented in 118 studies (0.37%). Medical records were not retrievable for 22 patients, yielding the final cohort of 96 patients with reported RPE. The median follow-up duration was 18.9 months (IQR: 7.8-45.7 months). Short-term events were noted in four patients, of whom one was asymptomatic. Of the three symptomatic patients, two experienced mild discomfort at injection site, and one had a tender swelling. Three of the four events had a prior intravenous contrast extravasation for a contrast-enhanced computed tomography performed earlier during the day, and a 99m Tc-MDP injection later at the same site likely leading to RPE. None of the long-term local events had any plausible link with the RPE event. Conclusion: Reported RPE were rare and short-term local symptoms were observed in three patients (0.009%), all of which were likely related to the prior higher volume intravenous contrast extravasation. The smaller volume diagnostic RP injections for WBBS are highly unlikely to cause local symptoms on their own. No patient had any long-term adverse event with a plausible link to the RPE.