Focal cortical dysplasia: Comparison of MRI and FDG-PET

Purpose: The purpose of this work was to compare the use of MRL and [F-18]f luorodeoxyglucose (FDG) positron emission tomography (PET) in the diagnosis of focal cortical dysplasia (FCD). Method: Nineteen patients with surgically proven FCD were analyzed retrospe ctively. MRI was performed in all patients, and FDG-PET was performed in 17 patients. We compared the MR and FDG-PET finding's of FCD according to the histologic findings that were classified into three grades. Results: Four cases were classified as Grade I, 4 cases as Grade II, and ii cases as Grade III FCD. The lesions were detected on MRI in 9 (82%) of the 11 patients with Grade III FCD and in only 1 (13%) of the 8 patients with Grade I and II FCD. Cortical hypometabolism of the lesion was revealed on F DG-PET in 6 (86%) of the 7 patients with Grade I and Il FCD and in 9 (90%) of the 10 patients with Grade III FCD. The extent of the cortical abnormali ty was larger on FDC-PET than on MRI in 11 (65%) of the 17 patients. Conclusion: FDG-PET is more useful in delineating the cortical abnormality in patients with mild degrees of FCD. The extent of the lesion was larger o r similar on FDG-PET compared with that of the MRI.