Is Intraoperative Diffusion Tensor Imaging at 3.0T Comparable to Subcortical Corticospinal Tract Mapping?

Is Intraoperative Diffusion Tensor Imaging at 3.0T Comparable to Subcortical Corticospinal Tract Mapping?

Neurosurgery - Current Issue

BACKGROUND:Primary brain tumors in motor eloquent areas are associated with high-risk surgical procedures because of potentially permanent and often disabling motor deficits. Intraoperative primary motor cortex mapping and corticospinal tract (CST) monitoring are well-developed and reliable techniques. Imaging of the CST by diffusion tensor tractography (DTT) is also feasible. OBJECTIVE:To evaluate the practical value of 3.0T intraoperative MRI (iMRI) with intraoperative DTT (iDTT) in surgery close to the CST, and to compare high-field iDTT with intraoperative neurophysiological CST mapping during glioma and metastasis resection in a routine setting. METHODS:Twenty-five patients (13 males, 12 females, median 47 years) were enrolled prospectively from June 2010 to June 2012. Patients were included if they had a solitary supratentorial intracerebral lesion compressing or infiltrating the CST according to preoperative MRI. Subcortical CST mapping was performed by monopolar (cathodal) stimulation (500 Hz, 400 μs, 5 pulses). CST DTT was made both at preoperative and intraoperative 3.0T MRI. Subcortical motor-evoked potential threshold current and probe-CST distance were recorded at 155 points before and at 103 points after iMRI. Current-distance correlations were performed both for pre-iMRI and for post-iMRI data. RESULTS:The correlation coefficient pre-iMRI was R = 0.470 (P < .001); post-iMRI, the correlation coefficient was R = 0.338 (P < .001). MRI radical resection was achieved in 17 patients (68%), subtotal in 5 (24%), and partial in 3 (12%). Postoperative paresis developed in 8 patients (32%); the paresis was permanent in 1 case (4%). CONCLUSION:The linear current-distance correlation was found both in pre-iMRI and in post-iMRI data. Intraoperative image distortion appeared in 36%. Neurophysiological subcortical mapping remains superior to DTT. Combining these 2 methods in selected cases can help increase the safety of tumor resection close to the CST. ABBREVIATIONS:cont-MEP, continuous motor-evoked potentialsCRDT, complete resection of detectable tumorCRET, complete resection of enhancing tumorCS, central sulcusCST, corticospinal tractDTI, diffusion tensor imagingDTT, diffusion tensor tractographyFOV, field of viewFSPGR, fast spoiled gradient-recall-echoiDTT, intraoperative diffusion tensor tractographyiMRI, intraoperative magnetic resonance imagingiPT, intraoperative pyramidal tractiUS, intraoperative ultrasoundMEP, motor-evoked potentialNEX, number of excitationsPMC, primary motor cortexPost-Dist, distances measured after iMRIPre-Dist, distances measured before iMRIPT, pyramidal tractscMEP, subcortical motor-evoked potentialSEP, somatosensory-evoked potentialSNR, signal-to-noise ratioWHO, World Health Organization

Original Article: http://journals.lww.com/neurosurgery/Fulltext/2013/11000/Is_Intraoperative_Diffusion_Tensor_Imaging_at_3_0T.8.aspx

Julio Pereira, MD

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