Fig. 4

Viability and gain of pancreatic islets (a, b), MR signal (c, d) and fluorescent signal (e, f) from optical fluorescence imaging of phantoms containing PIs labelled by microporation using the standard procedure (left: a, c, e) and modified protocol (right: b, d, f). MR signal (c, d) was expressed as a contrast-to-noise ratio, fluorescent signal intensity is in arbitrary units proportional to average radiance. Significant decrease of viability (P < 0.05, marked by “*”) compared to endocytosis was observed at voltage 900 V and higher in the case of the standard protocol (a) and 800 V and higher in the case of modified protocol (b). Gain was substantially lower (P < 0.05, marked by “×”) in the case of the standard protocol at any voltage setting (a); whereas in the case of the modified protocol (b), significant gain decrease was observed at 1000 V only (P < 0.05, marked by “×”)