gms | German Medical Science

Objective: To preoperatively localize and intraoperatively visualize components of the language network, such as Broca’s and Wernicke’s area, typically functional MRI (fMRI) is performed using word generation tasks or semantic decision tasks. These active fMRI tasks are heavily dependent on the patient’s compliance and ability to perform the task in an adequate manner, which is often complicated due to cognitive impairment, language deficits or stress related to following surgery. Inadequate task performance thereby often leads to insufficient identification of language areas and adaption of surgical strategies to ensure neurological functions postoperatively.

Method: To overcome this drawback we developed a passive fMRI paradigm for language network activation. The paradigm consists of a pseudo-randomized blocked design of auditory stimuli (sentences) and white noise. Patients only had to listen to the presented stimuli. To evaluate its ability to outline the language network in the clinical setting 3 patients (1: male, age 45, left handed; 2: female, age 53, right handed, 3: male, age 40, right handed) with gliomas close to the language areas within the left hemisphere underwent this 10 minute passive fMRI task at a 3T Trio MRI System (Siemens, Erlangen, Germany) using a T2* weighted echo planar imaging sequence. Analysis was performed using SPM12 including realignment, smoothing and analysis applying a general linear model. P<0.05 (family wise error corrected) was used as statistical threshold.

Results: Using the passive fMRI paradigm we were able to outline language network components such as Broca’s and Wernicke’s area besides further components such as Broca’s homologue in all 3 patients with cluster sizes of more than 200 voxels. Patient 1 revealed a right, patient 2 a left lateralized language network. Patient 3 (tumor recurrence) revealed right lateralized language components with less activation in the left hemisphere in comparison to the other patients. Word generation tasks thereby only outlined a plausible activation pattern in patient 3 with cluster size of 40 voxels visualizing Broca’s area.

Conclusions: Passive fMRI shows promising results for outlining language network components in patients with gliomas close to language areas. Further work will focus on optimization (efficiency and reliability) of the paradigm for integration in clinical practice.