Evaluation of technetium-99m metastable nanocolloid as an imaging agent for performing milk scans

OBJECTIVE: The aim of this study was to determine whether technetium-99m ((99m)Tc) nanocolloid was a suitable alternative tracer for carrying out milk scan studies in pediatric patients. PARTICIPANTS AND METHODS: Twenty-seven milk scans performed with (99m)Tc nanocolloid were retrospectively assessed for identification of significant esophageal hold-up, gastroesophageal reflux, pulmonary aspiration, and gastric emptying (GE). Scans were also assessed for liver, spleen, and bone marrow uptake. GE results were compared with those of 27 randomly selected normal GE studies carried out using (99m)Tc tin colloid. RESULTS: None of the studies had liver, spleen, or bone marrow uptake, and all studies were interpretable. Significant esophageal hold-up and gastroesophageal reflux was observed in 11 and 48% of the patients, respectively. Only one patient had evidence of pulmonary aspiration, and all patients had normal GE at 2 h after radiolabeled milk ingestion. The average rate of GE at 2 h was faster in the (99m)Tc nanocolloid group compared with the (99m)Tc tin colloid group (8.85% retained±8.96% vs. 15.48% retained±10.52%, P=0.016). CONCLUSION: Our findings show that (99m)Tc nanocolloid is technically a suitable alternative to (99m)Tc sulfur colloid for performing milk scans. However, we could not conclude with certainty on the comparison of the GE rates of (99m)Tc nanocolloid and (99m)Tc tin colloid. This was because of the variability in the two population groups as well as the fact that the milk that was used in each patient was individualized to the patient and was not standardized.