Evaluation of the quality of the radiopharmaceutical 99mTc-MIBI and its influence on image quality in myocardial perfusion scintigraphy

This study evaluated the quality of the 99mTc-MIBI radiopharmaceutical from different manufacturers, used in three nuclear medicine services (NMS) in Recife-PE, through labeling procedure of each service. It was observed their biodistribution by quantifying the activity present in the organs of interest (heart / liver), the influence and interference in image quality and in myocardial scintigraphy diagnosis exam. In these NMS (A, B and C) were done quality controls in the eluates of 99Mo/99mTc generators (radionuclidic, chemical and radiochemical purity and pH) and of the 99mTc-MIBI radiopharmaceutical (radiochemical purity and pH) used in myocardial scintigraphy exam. In the case of radiochemical purity (RCP), was used the thin layer chromatography technique; after the chromatographic ran on, the plates were analyzed both in the dose calibrator, and in scintillation camera of each NMS. The radiopharmaceutical biodistribution was evaluated through the activities present in the heart and liver images in 60 patients, using the technique of combined images counting. Five nuclear physicians analyzed 24 images through myocardial perfusion visual interpretation during stress, it was verified the agreement degree among them. The results of the quality control showed that all eluate samples were in agreement with the manufacturers in relation to radionuclidic purity and pH. In relation to chemical purity, 10% of the services samples B and C showed Al+3 values above 10 ppm. In the RCP, it was observed that using the scintillation camera, only 22% of the samples would be discarded, while with dose calibrator would be 78%, indicating that the scintillation camera is more sensitive in chromatographic pale analysis. For the labeled radiopharmaceutical, the services B and C presented respectively one and three samples with RCP percentage below 90%. However, C service presented the lowest medium to liver/heart proportions, showing that this factor does not depends on the labeling efficiency. In the images evaluation, in relation to perfusion defect degree, were observed a lower concordance number (20%) among the evaluators in the exams group with radiopharmaceutical labeling problems. These results suggested that problems in radiopharmaceutical labeling can interfere in image interpretation, emphasizing the need to comply with ANVISA (Brazilian Health Surveillance Agency) requirements in relation to quality controls in radiopharmaceuticals implementation before its administration to the patient. (author)