Objective: Percutaneous peripheral nerve stimulation (PNS) is an FDA-cleared pain treatment. Occasionally, fragments of the lead (MicroLead, SPR Therapeutics, LLC, Cleveland, OH, USA) may be retained following lead removal. Since the lead is metallic, there are associated magnetic resonance imaging (MRI) risks. Therefore, the objective of this investigation was to evaluate MRI-related issues (i.e., magnetic field interactions, heating, and artifacts) for various lead fragments.Methods: Testing was conducted using standardized techniques on lead fragments of different lengths (i.e., 50, 75, and 100% of maximum possible fragment length of 12.7 cm) to determine MRI-related problems. Magnetic field interactions (i.e., translational attraction and torque) and artifacts were tested for the longest lead fragment at 3 Tesla. MRI-related heating was evaluated at 1.5 Tesla/64 MHz and 3 Tesla/128 MHz with each lead fragment placed in a gelled-saline filled phantom. Temperatures were recorded on the lead fragments while using relatively high RF power levels. Artifacts were evaluated using T1-weighted, spin echo, and gradient echo (GRE) pulse sequences. Results:The longest lead fragment produced only minor magnetic field interactions. For the lead fragments evaluated, physiologically inconsequential MRI-related heating occurred at 1.5 Tesla/64 MHz while under certain 3 Tesla/128 MHz conditions, excessive temperature elevations may occur. Artifacts extended approximately 7 mm from the lead fragment on the GRE pulse sequence, suggesting that anatomy located at a position greater than this distance may be visualized on MRI.Conclusions: MRI may be performed safely in patients with retained lead fragments at 1.5 Tesla using the specific conditions of this study (i.e., MR Conditional). Due to possible excessive temperature rises at 3 Tesla, performing MRI at that field strength is currently inadvisable.

Mitochondrial dysfunction is shown to be associated with many diseases, such as neurodegeneration, diabetes, cardiomyopathy or developmental delay, etc. Energy generation in the mitochondria meets the demands and is extremely specific to different tissues. The brain is rather small (1-2% of body weight) in relation to the whole body, but it consumes ten times more oxygen and glucose than any other tissue. Oxygen is consumed predominantly in the mitochondria, in the electron transport chain (ETC) in a process that is coupled to the production of ATP. Singlet oxygen is the electronically excited state of molecular oxygen (lowest excited state of the dioxygen molecule) which is less stable than molecular oxygen in the electronic ground state. Singlet oxygen is largely accepted to be a highly damaging radical that is made use of in the photodynamic therapy of cancer (PDT), always in the presence of photosensitizers. Here, we report for the first time we report positive effects of singlet oxygen, specific to the mitochondrial energy metabolism. We have found that illumination of primary co-culture of neurons and astrocytes with laser which wavelength that coincides with one of the highest absorption peaks of the oxygen molecule, produces high level of singlet oxygen inside the cells. We have also found that this type of laser irradiation increases mitochondrial membrane potential, stimulates NADH-and FADH-dependent respiration and significantly increases the efficiency of oxidative phosphorylation. Finally, this results in an increase in the ATP levels in mitochondria of neurons and astrocytes. It should be noted that these effects are dependent on the irradiation dose and an increase of the dose over a certain threshold lead to toxic effects.