99mTc lung scintigraphy at different time points (30 min, 90 min and 24 hours) after endobronchial infusion of adipose derived mesenchymal stem cells (ADmSCs). Retention of radiolabeled cells (99mTc-HMPAO) (right lung-RT) in comparison to cells with free 99mTcO4 (without ceretec-HMPAO) (left lung-LT) was estimated with computerized image analysis by drawing regions of interest (roi) and calculating the average counts/pixels (aver.count). As depicted in panels A (anterior view) and B (posterior view), signal intensity was significantly stronger in the right lung compared to left lung (roi 334.65 vs. 93.69, respectively), 30 minutes after endobronchial infusion of ADmSCs and this difference remained 90 minutes (panels C and D) (roi 227.24 vs. 37.89, respectively), as well as 24 hours (panels E and F) (roi 14.76 vs. 1.22, respectively) after the infusion, indicating the presence of radiolabeled ADmSCs (99mTc-HMPAO). On the contrary, ADmSCs instilled within the left lung were reconstituted only with free technetium (99 mTcO4-) without ceretec-HMPAO and therefore produced minimal signal intensity within the lung. Free technetium uptake by the stomach is a normal finding due to the presence of free pertechnetate.