18F-FDG PET/CT can predict response to neoadjuvant chemotherapy at an early stage.

SUMMARYPurpose: To validate the use of 18F-fluorodeoxyglucosepositron emission tomography/magnetic resonance imaging (FDG-PET/MRI) coregistration for epileptogenic zone detection in children with MRI nonlesional refractory epilepsy and to assess its ability to guide a second interpretation of the MRI studies. Methods: Thirty-one children with refractory epilepsy whose MRI results were nonlesional were included prospectively. All patients underwent presurgical evaluation following the standard protocol of our epilepsy unit, which included FDG-PET and FDG-PET/MRI coregistration. Cerebral areas of decreased uptake in PET and PET/MRI fusion images were compared visually and then contrasted with presumed epileptogenic zone localization, which had been obtained from other clinical data. A second interpretation of MRI studies was carried out, focusing on the exact anatomic region in which hypometabolism was located in FDG-PET/MRI fusion images.Key Findings: Both FDG-PET and FDG-PET/MRI detected hypometabolism in 67.8% of patients, with good concordance on a subject basis and on the cerebral region involved (j statistic = 0.83 and 0.79, respectively). Hypometabolism detected by single PET, as well as by PET/MRI fusion images, was located in the same hemisphere, as indicated by electroclinical data in 58% of patients, and at the same place in 39% of cases. Of the patients who showed hypometabolism on PET/MRI, 43% also experienced changes in the guided second MRI interpretation, from nonlesional to subtlelesional. Significance: PET/MRI coregistration is an imaging variant that is at least as accurate as PET alone in detecting epileptogenic zone in pediatric nonlesional patients, and can guide a second look at MRI studies previously reported as nonlesional, turning a meaningful percentage into subtle-lesional.

A precise assessment of the drug-resistant epileptic pediatric population for surgical candidacy is often challenging, and to date there are no evidence-based guidelines for presurgical identification of the epileptogenic zone. To evaluate the usefulness of radionuclide imaging techniques for presurgical evaluation of epileptic pediatric patients, we compared the results of video-electroencephalography (EEG), brain MR imaging, interictal SPECT, ictal SPECT, subtraction ictal SPECT coregistered to MR imaging (SISCOM), and interictal PET with 18 F-FDG. Methods: Fifty-four children with drug-resistant epilepsy who had undergone video-EEG monitoring, brain MR imaging, interictal and ictal brain perfusion SPECT, SISCOM, and 18 F-FDG PET were included in this study. All abnormal findings revealed by these neuroimaging techniques were compared with the presumed location of the epileptogenic zone (PEZ) as determined by video-EEG and clinical data. The proportion of localizing studies for each technique was statistically compared. In the 18 patients who underwent resective brain surgery, neuroimaging results were compared with histopathology results and surgical outcome. Results: SISCOM and 18 F-FDG PET concordance with the PEZ was significantly higher than MR imaging (P , 0.05). MR imaging showed localizing results in 21 of 54 cases (39%), SISCOM in 36 of 54 cases (67%), and 18 F-FDG PET in 31 of 54 cases (57%). If we consider SISCOM and 18 F-FDG PET results together, nuclear medicine imaging techniques showed coinciding video-EEG results in 76% of patients (41/54). In those cases in which MR imaging failed to identify any epileptogenic lesion (61% [33/54]), SISCOM or 18 F-FDG PET findings matched PEZ in 67% (22/33) of cases. Conclusion: SISCOM and 18 F-FDG PET provide complementary presurgical information that matched video-EEG results and clinical data in three fourths of our sample. SISCOM was particularly useful in those cases in which MR imaging findings were abnormal but no epileptogenic lesion was identified. Radionuclide imaging techniques are both useful and reliable, extending the possibility of surgical treatment to patients who may have been discouraged without a nuclear medicine approach.

The use of portable gamma cameras in theatre is in an early phase. The short period of time required during the surgical procedure will allow the surgical team to improve this technique until it can replace hand-held probes. The intraoperative acquisition of such images can predict the involvement of surgical margins, avoiding future surgical procedures.

ObjectivesSeveral studies using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) or diffusion tensor imaging (DTI) have found both temporal and extratemporal abnormalities in patients with mesial temporal lobe epilepsy with ipsilateral hippocampal sclerosis (MTLE-HS), but data are lacking about the findings of both techniques in the same patients. We aimed to determine whether the extent of 18F-FDG-PET hypometabolism is related to DTI abnormalities.MethodsTwenty-one patients with MTLE-HS underwent comprehensive preoperative evaluation; 18 (86%) of these underwent epilepsy surgery. We analyzed and compared the pattern of white matter (WM) alterations on DTI and cortical hypometabolism on 18F-FDG-PET.ResultsWe found widespread temporal and extratemporal 18F-FDG-PET and DTI abnormalities. Patterns of WM abnormalities and cortical glucose hypometabolism involved similar brain regions, being more extensive in the left than the right MTLE-HS. We classified patients into three groups according to temporal 18F-FDG-PET patterns: hypometabolism restricted to the anterior third (n = 7), hypometabolism extending to the middle third (n = 7), and hypometabolism extending to the posterior third (n = 7). Patients with anterior temporal hypometabolism showed DTI abnormalities in anterior association and commissural tracts while patients with posterior hypometabolism showed WM alterations in anterior and posterior tracts.ConclusionsPatients with MTLE-HS have widespread metabolic and microstructural abnormalities that involve similar regions. The distribution patterns of these gray and white matter abnormalities differ between patients with left or right MTLE, but also with the extent of the 18F-FDG-PET hypometabolism along the epileptogenic temporal lobe. These findings suggest a variable network involvement among patients with MTLE-HS.