The "Iceberg Phenomenon": As Soon as One Technological Problem in NOTES Is Solved, the Next One Appears!

PURPOSE: Though already proclaimed about 7 years ago, natural orifice transluminal endoscopic surgery (NOTES) is still in its early stages. A multidisciplinary working team tried to analyze the technical obstacles and identify potential solutions. METHODS: After a comprehensive review of the literature, a group of 3 surgeons, 1 gastroenterologist, 10 engineers, and 1 representative of biomedical industry defined the most important deficiencies within the system and then compiled as well as evaluated innovative technologies that could be used to help overcome these problems. These technologies were classified with regard to the time needed for their implementation and associated hindrances, where priority is based on the level of impact and significance that it would make. RESULTS: Both visualization and actuation require significant improvement. Advanced illumination, mist elimination, image stabilization, view extension, 3-dimensional stereoscopy, and augmented reality are feasible options and could optimize visual information. Advanced mechatronic platforms with miniaturized, powerful actuators, and intuitive human-machine interfaces could optimize dexterity, as long as enabling technologies are used. The latter include depth maps in real time, precise navigation, fast pattern recognition, partial autonomy, and cognition systems. CONCLUSION: The majority of functional deficiencies that still exist in NOTES platforms could be overcome by a broad range of already existing or emerging enabling technologies. To combine them in an optimal manner, a permanent dialogue between researchers and clinicians is mandatory.

Spatial congruence of neuronavigated transcranial magnetic stimulation and functional neuroimaging.

OBJECTIVES: Transcranial magnetic stimulation (TMS) is progressively gaining relevance as a tool in cognitive neuroscience and clinical research. However, most studies in this field do not consider individual anatomy. Neuronavigational devices allow to guide the coil to a specific cortical area, predetermined by functional magnetic resonance imaging (fMRI). Therefore, it is crucial to know whether the area of a certain function as identified by fMRI corresponds to the area where the TMS should be placed in order to influence this function. METHODS: We investigated the spatial relation between the cortical area activated by a motor task in fMRI and the area of magnetically evoked motor potentials (MEP) in 8 subjects, using a spacing of 5x5 mm. A neuronavigational system was adapted for coil positioning and for the registration of the stimulation coordinates. RESULTS: A spatial divergence of the centers of gravity from fMRI and MEP was found with a mean distance of about 10 mm, with the MEP centers being, by a mean derivation of 7.5 mm, consistently anterior to the center of fMRI activation. However, regarding MEP areas and fMRI activities, a large overlap was found for stimulation intensities of both 110 and 120% motor threshold. CONCLUSIONS: The combination of fMRI and neuronavigated TMS is useful for non-invasive investigation of individual cortical functions predetermined by fMRI. Whereas both are spatially by and large congruent, discrepencies in the exact spatial relation between MEP and fMRI areas should be considered and further studied.