PETMR improves presurgical lesion detection in paediatric epilepsy
In children with difficulty-to-diagnose epilepsy, PETMR can pinpoint areas of the brain responsible for seizures, even when MRI scans are negative or inconclusive. A new study of a large paediatric cohort, including children younger than six years old, found that combining PETMR findings with EEG results and a structured presurgical evaluation improved the identification of seizure-causing brain tissue and informed treatment decisions. This research was published in the August issue of The Journal of Nuclear Medicine.
Children with underlying structural causes of epilepsy may benefit from early surgical intervention, however, these cases are often complex and hard to diagnose. Recent studies show that PETMR, which images both the function and structure of the brain, can be valuable in detecting and localizing brain lesions that cause seizures.
“We know PETMR is a beneficial imaging tool for patients with epilepsy, however, the current scientific literature is limited as it mixes paediatric and adult subjects,” said Diego Cecchin, MD, director of the Unit of Nuclear Medicine and postgraduate School of Nuclear Medicine in the Department of Medicine at University-Hospital of Padova in Italy. “In our study we sought to clarify the role of PET/MRI in the presurgical evaluation of paediatric epilepsy, including in very young children.”
The retrospective study included 79 patients 18-years-old or younger who had a diagnosis of focal epilepsy under surgical evaluation and had a negative or inconclusive MRI result. Data was reviewed in several phases: (0) evaluation of previous MRI scans; (1) masked review of PETMR-acquired MR images only; (2) joint assessment of PET and MRI data by a nuclear medicine and neuroradiology physicians; and (3) verification of PETMR findings as compared to EEG results.
No images from phase 0 were conclusive, in concordance with the study inclusion criteria, and in phase 1, 36 MR-only images were positive. Joint PETMR reading in phase 2 revealed that 46 patients had PET-positive/MRI-positive results, 24 had PET-positive/MRI-negative results, and eight had PET-negative/MRI-negative results. In phase 3, PET-positive/MRI-positive findings demonstrated high accuracy in identifying lesions when compared EEG results, particularly focal cortical dysplasia.
The study also identified two distinct groups of patients showing hypometabolism, or reduced brain metabolism. In the first hypometabolic group, careful re-evaluation of the MRI scans revealed structural brain abnormalities. In the second group, areas of abnormal hypometabolism were often mild, and no conclusive brain lesions were found on MRI even after detailed review. These children were much more likely to have EEG and clinical findings that did not match the imaging results, making them less likely candidates for epilepsy surgery.
Based on the clinical, imaging and EEG data, 24 patients underwent surgery, and five underwent thermocoagulation to remove brain tissue. Of these children, 76 percent were free from seizures after two years of follow-up.
“These findings highlight the important role of molecular imaging and nuclear medicine in evaluating children with focal epilepsy, demonstrating that PET/MRI can be used safely and reliably even in very young patients,” noted Concetta Luisi, MD, pediatric neurologist and epileptologist at the Neurology, Epilepsy and Movement Disorders Unit of Bambino Gesù Children’s Hospital in Rome, Italy. “As more data become available, this approach could help clinicians identify the children most likely to benefit from epilepsy surgery, better understand distinct patterns of brain metabolism, and improve the integration of imaging findings with clinical and EEG data to guide treatment decisions.”
Picture: (A) Negative case (PET-negative/MRI-negative). (B) Right frontal hypermetabolic area (white arrow) in PET-positive/MRI-positive patient. On MRI, slight cortical–subcortical blurring was observed. Patient (male, 1.5-years old) underwent right frontal disconnection, and focal cortical dysplasia (FCD) IIa was diagnosed. (C) Large left parietotemporooccipital hypometabolism (white arrows) associated with cerebellar diaschisis (white asterisk) in PET-positive/MRI-positive case. Hypometabolism was more extensive than mild blurring identified by MRI in temporal lobe and was useful to guide surgical decision. Patient (male, 12-years-old) underwent left temporooccipital disconnection, and FCD IIa was diagnosed. (D) Temporal hypometabolism (white arrow) corresponding to MRI alterations (PET-positive/MRI-positive) as T2 fluid-attenuated inversion recovery hyperintensity, suggesting hippocampal sclerosis. Patient (female, 5 years-old) was drug-resistant at first evaluation but subsequently stopped having epileptic seizures, and her family decided not to proceed with surgery. (E) Right frontal PET hypometabolism (white arrow) with no MRI alterations (PET-positive/MRI-negative), possibly suggesting FCD. PET data were useful to guide SEEG implantation. Patient (female, 5-years-old) underwent right frontal disconnection, and FCD I was diagnosed.
Source: SNNMI.
The authors of “18F-FDG PET/MRI in Pediatric Focal Epilepsies” include Concetta Luisi, Luca De Palma, and Nicola Specchio, Neurology, Epilepsy and Movement Disorders, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy; Cristina Campi, Dipartimento di Matematica, University of Genova, Genova, Italy, and IRCCS Ospedale Policlinico San Martino, Genova, Italy; Clementina Boniver, Neurologia e Neurofisiologia Pediatrica, Dipartimento di Salute della Donna e del Bambino, Padua University Hospital, Padua, Italy; Ignazio D’Errico and Mariagiulia Anglani, Neuroradiology Unit, University Hospital of Padua, Padua, Italy; Matia Martucci, Neuroradiology Unit, Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy; Andrea Landi, Neurosurgery Unit, Padua University Hospital, Padua, Italy; Alessandro De Benedictis, Neurosurgery Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy; Rossella Simeone, Francesca Serani, and Pietro Zucchetta, Department of Medicine (DIMED), University of Padua, Italy; Stefano Sartori, Neurologia e Neurofisiologia Pediatrica, Dipartimento di Salute della Donna e del Bambino, Padua University Hospital, Padua, Italy; and Diego Cecchin, Department of Medicine (DIMED), University of Padua, Italy, Nuclear Medicine Unit, Hospital of Padua, Padua, Italy, and Padova Neuroscience Center, University of Padua, Padua, Italy.
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