Functional MRI in the Presurgical Evaluation of Patients with Brain Tumors: Characterization of the Statistical Threshold

Abstract

We investigated whether an optimal statistical threshold could be obtained in healthy controls and patients with brain tumors undergoing presurgical functional MRI assessment. The volumes of activation of the primary motor cortex (PMC) and the lateral prefrontal cortex (PFC) were measured for the tumor and nontumor sides in 24 patients and 8 controls using four parameters; p values ranged between 10^–2 and 10^–31. The mean r value for first activation in the PMC was higher in controls than for both the tumor and nontumor sides in patients. The mean r value for ‘first activation in the noise area’ and ‘PMC and PFC ratio’ in controls was significantly different from the mean r value for the tumor and nontumor sides in patients (p < 0.05). The magnitude of the range of r values for the nontumor side was closer to the tumor side data than to the control data. It is imperative to evaluate functional MRI data with a wide range of statistical parameters, especially in the assessment of tumor patients.

Brain Tumors: The Influence of Tumor Type and Routine MR Imaging Characteristics at BOLD Functional MR Imaging in the Primary Motor Gyrus

“…Because functional MR imaging activation volumes can be threshold dependent (22), three thresholds were used to compare functional MR imaging activation volumes (from a maximal correlation score of 0.62 determined by multiple comparison correction, a minimal correlation score of 0.4, and an in-between score of 0.5). Statistical significance was set at P , .001.…”

Infiltration of the basal ganglia by brain tumors is associated with the development of co-dominant language function on fMRI

“…Functional activation maps were generated at p<0.001 (uncorrected). No standard p value was used because individual patient fMRI maps are not amenable to such practice (Chang et al, 2010). To reduce false positive activity from large venous structures or head motion, voxels in which the standard deviation of the acquired time series exceeded 8% of the mean signal intensity were set to zero.…”

Evaluation of vascular reactivity to overcome limitations of neurovascular uncoupling in BOLD fMRI of malignant brain tumors

“…Патологические сосуды злокачественных опухолей сформированы аномально как структурно, так и функционально [5], изменена также их сосудистая реактивность [10][11][12][13][14]. У пациентов со злокачественными опухолями мозга патологические сосуды опухоли часто не отвечают на повышение активности нейронов, что приводит к ослаблению BOLD-ответа [15]. Наличие перитуморального отека также изменяет вазореактивность, усложняя построение фМРТ-карт.…”