Intraoperative Diffusion-Weighted Imaging for Visualization of the Pyramidal Tracts. Part I: Pre-Clinical Validation of the Scanning Protocol

Abstract

Integration of intraoperative diffusion-weighted imaging (iDWI) into neuronavigation can be potentially useful for identification of the pyramidal tract during surgery for parenchymal brain lesions. The technique of iDWI using an intraoperative MR scanner of low magnetic field strength (0.3 Tesla) has been developed. For image acquisition, a specially designed solenoid radiofrequency receiver coil integrated with a modified Sugita head holder (head-holder coil) was used. While the sensitivity characteristics of the head-holder coil were found to be 29% lower compared to a diagnostic quadrature head coil, they were sufficient to obtain iDWI images of good quality. The relationship between the angle of the motion probe gradient (MPG) pulse to the vertical axis and pyramidal tract contrasting were examined in 4 healthy men with a mean age of 30+/-5.7 years. The contrast ratio reached a maximum when the MPG pulse was applied exactly in the anteroposterior direction. The difference of the contrast ratio between right and left sides was not statistically significant. Pyramidal tract visualization became worse and the contrast ratio was reduced when the MPG pulse was applied at different angles to the vertical axis; the reduction rate varied from 20.1 to 27.9% for each 15 degrees of rotation irrespective of its side. In conclusion, the developed scanning protocol for iDWI using an originally designed head-holder coil allowed effective visualization of the pyramidal tracts using an intraoperative MR scanner of low magnetic field strength.

Advanced Surgical Management of Gliomas: Technological Requirements, Concept of Information-Guided Resection, and Clinical Results

“…Nevertheless, all surgical devices that are used within the 5-gauss line, such as operating table (MOT2000-MRI; Mizuho Ltd., Tokyo, Japan) and operating microscope (MRI-30; Mitaka Co., Tokyo, Japan) are constructed from non-ferromagnetic material to prevent accidents and avoid image artifacts. Originally developed radiofrequency receiver coil integrated with Sugita head-holder (Head-holder coil; Mizuho Ltd., Tokyo, Japan) significantly improved the quality of the intraoperative images (Ozawa et al, 2008a(Ozawa et al, , 2008b. Positioning of the coil in close vicinity to the visualized region provides one an opportunity to perform MRI investigations with minimal distortion artifacts and maximum structure contrasting in any plane irrespectively to orientation of the object.…”

Identification of the Pyramidal Tract by Neuronavigation Based on Intraoperative Diffusion-Weighted Imaging Combined with Subcortical Stimulation

“…A head-holder integrated with a radiofrequency receiver coil was used [20,21] . Surgical procedures were performed 1.5 m away from the MR scanner and the surgical table with the patient was moved to the scanner for MR imaging.…”

“…We have developed a neuronavigation system based on intraoperative DWI (iDWI) to preserve the important tracts during neurosurgical procedures [20,21] . The system minimizes the displacement between the tract image and the real position due to the surgical procedure by incorporating intraoperative DWI using intraoperative MRI, resulting in more precise navigation.…”

Shift of the Pyramidal Tract During Resection of the Intraaxial Brain Tumors Estimated by Intraoperative Diffusion-Weighted Imaging

“…6) An original radiofrequency receiver coil integrated with a modified Sugita head holder (Head-holder coil; Mizuho Ltd., Tokyo) was used. 17,18) During routine procedure iMR imaging was usually performed at least twice: after craniotomy and completeness of the approach to the tumor and after resection of the neoplasm. If additional removal of the lesion is required iMR imaging investigation was repeated.…”