Classification and epileptic foci localization of infantile spasms using hybrid PET/MR

• Published in: The Journal of nuclear medicine (1978) Vol. 59; p. 305
• Main Authors: Dang, Haodan, Liu, Jiajin, Wang, Ruimin, Zhang, Jinming, Liu, Changbin, Yan, Xu, Lin, Mu, Tian, Jiahe, Xu, Baixuan
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01.05.2018
• Subjects: Adrenocorticotropic hormone; Attenuation; Brain; Children; Classification; Complementarity; Convulsions & seizures; Cortex; Deformation; Diagnosis; Diagnostic systems; Diffusion coefficient; Dysplasia; EEG; Electroencephalography; Endocrine therapy; Epilepsy; Etiology; Evaluation; Fluorine isotopes; Image classification; Image detection; Infants; Informed consent; Lesions; Localization; Magnetic resonance imaging; Medical imaging; Metabolism; Morphology; Neuroimaging; NMR; Nuclear magnetic resonance; Nuclear medicine; Patients; Positron emission; Positron emission tomography; Quantitative analysis; Radioisotopes; Seizures; Sensitivity analysis; Spasms; Substantia alba; Tomography
• ISSN: 0161-5505; 1535-5667

Purpose: The purpose of this study was to evaluate the initial findings in classification and in detection of the epileptic foci using hybrid positron emission tomography/magnetic resonance (PET/MR) in children diagnosed with infantile spasms,and to discuss the therapeutic efficacy of the therapy with adrenocorticotropic hormone (ACTH) among PET/MR positve, PET-positive and MR-positive groups. Materials and Methods: A total of 128 children diagnosis with infant spasm were included, with signed informed consent before undergoing PET/MR scan. All patients were subsequently treated with ACTH within 3 weeks after PET/MR scan. The examination of PET/MR includes F-18 fluorodeoxyglucose(18F-FDG) PET and MR sequences. PET attenuation maps generated on the basis of the ultrashort echo time(UTE) MRI sequence were applied. MRI imaging was performed simultaneously to PET imaging using the following sequence protocol:(1) a sagittal T1-weighted sequence magnetisation-prepared rapid gradient-echo (T1 MPRAGE);(2) a transaxial T2-weighted sequence Fluid attenuation inversion recovery(T2WI FLAIR); (3) a transaxial diffusion-weighted image (DWI) sequences with double b values (b1=50s/mm2, and b2=1000s/mm2) . According to the latest consensus standards, infant spasm can be classified into three groups based on etiology, including clinical etiology group, structure / metabolism group and unknown etiology group. Firstly, a nuclear medicine doctor and a radiologist both with more than 5-year work experience analyzed the MR morphological images (including T1WI, T2WI) and PET images of all the patients to identify lesion with location and initial qualitative diagnosis. The diagnosis of MR and PET images were made independently and were subsequently combined. The lesion localized with both MR and PET imaging concordantly was considered as the epileptic foci. These detected cases were included into the structural / metabolic groups. Among the remaining cases, a semi quantitative measurement of apparent diffusion coefficient (ADC) and standard uptake value(SUVmax) with suspected brain areas according to electroencephalography( EEG) results were measured to detect slight epileptic foci new structural / metabolic cases with the value of {(lesion-control) / control} greater than 15% as the cut-off,according to the previous research. The patients with no positive finding from PET and MR images were assigned to unknown etiology group. Results: Based on the classification criterial above, we have following finding: 1) The total 128 cases were divided into unknown etiology group with 50 cases and structure / metabolism group with 78 cases according to PET / MR and EEG; 2) In structure / metabolism group, 23 cases were consistently detected on PET and MR anatomical images. The diagnosis included obvious brain deformities, cortical dysplasia and abnormal signal in white matter. Another 16 cases were detected only the MR morphological images but not on PET images. The diagnosis included schizencephaly and inconspicuous signal in grey or white matter; 3) 39 cases / metabolic cases were newly detected in semi-quantitative diagnosis with the combination of PET and ADC. The efficacy of each group of patients after treatment with ACTH: 1) unknown etiology group: 19/50; 2) structures / metabolic group: 51/78. Discussion & Conclusion: Semi-quantitative evaluation of ADC and SUVmax with hybrid PET/MR can increase the diagnostic accuracy in detecting inconspicuous epileptic foci, especially in cases of negative finding with PET or MR morphological imaging. It may due to the complementarity of the integrated images of both anatomic and functional data. Meanwhile, it also showed advantages of quantitative imaging that provide high sensitivity in diagnosis than visual evaluation. In addition, the classification of infantile spasms showed different prognosis result, which indicated the positive finding of PET / MR may be a prognostic factor.