Article
Preoperative navigated TMS-DTI-based tracking of the optic radiation – a proof of concept
Präoperative navigierte TMS-DTI-basierte Traktographie der Sehbahn – ein Konzeptnachweis
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Authors
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Karlijn Hakvoort
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland; Universitätsklinikum Aachen, Neurosurgical Artificial Intelligence Laboratory Aachen (NAILA), Aachen, Deutschland
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Jonas Ort
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland; Universitätsklinikum Aachen, Neurosurgical Artificial Intelligence Laboratory Aachen (NAILA), Aachen, Deutschland
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Julius Maximilian Kernbach
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland; Universitätsklinikum Aachen, Neurosurgical Artificial Intelligence Laboratory Aachen (NAILA), Aachen, Deutschland
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Hans Clusmann
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland
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Georg Neuloh
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland
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Daniel Delev
- Universitätsklinikum Aachen, Klinik für Neurochirurgie, Aachen, Deutschland; Universitätsklinikum Aachen, Neurosurgical Artificial Intelligence Laboratory Aachen (NAILA), Aachen, Deutschland
| Published: | June 4, 2021 |
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Outline
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Objective: The frequency of visual field deficits (VFD) after surgery in proximity to the optic radiation (OR) is high. Depending on its severity, VFD can cause a decrease in quality of life by affecting normal daily activities. Since localization of the OR can be challenging due to interindividual anatomical variation and severe tumor displacement or infiltration, we present a method for navigated TMS diffusion tensor imaging-based (TMS-DTI-based) OR tracking.
Methods: Twelve patients undergoing resective tumor or epilepsy surgery in proximity to the OR between June and November 2020, who underwent preoperative DTI sequences and occipital TMS, were enrolled in this study. In all 24 hemispheres, tractography of the OR was performed both anatomy-based (according to current literature) and TMS-based (seeding from positive TMS foci). Consecutively, OR tracts of the operated hemisphere were superimposed on the resection cavity and correlated to postoperative perimetry.
Results: TMS induced perception of phosphenes in 83% of patients (n=10), including patients with moderate preoperative VFD (n=6). Both patients in whom TMS was not able to induce perception of phosphenes showed severe preoperative VFD. We observed significant differences in course of the anatomy-based compared to the TMS-based OR, with the latter showing a more medial and caudal course in 9 out of 10 cases. In all 7 hemispheres with lesions in close proximity (<1 cm) to the OR, TMS-based OR mapped fibers more accurately and closer to the lesion than anatomy-based OR. Two of 5 patients had new VFD in postoperative perimetry. Superimposing of the OR on postoperative MRI in both patients demonstrated TMS-based OR fibers and not anatomy-based OR fibers within the resection cavity (Figure 1 [Fig. 1]), supporting the accuracy of TMS-based tracking.
Conclusion: Here we show that TMS-DTI-based tracking of the OR is feasible. There was a clear difference between the course of TMS-based and anatomy-based OR. In this limited patient group, TMS-based OR seemed to be more accurate, especially in cases with lesions in close proximity to the OR and/or when there was a lot of associated edema. Integration of TMS-DTI-based visualization into preoperative workup can possibly help reducing VFD after resective surgery.
