RESUMO
Background & objectives: There is a growing concern over the radiation exposure of patients from undergoing 18FDG PET/CT (18F-fluorodeoxyglucose positron emission tomography/computed tomography) whole body investigations. The aim of the present study was to study the kinetics of 18FDG distributions and estimate the radiation dose received by patients undergoing 18FDG whole body PET/CT investigations. Methods: Dynamic PET scans in different regions of the body were performed in 49 patients so as to measure percentage uptake of 18FDG in brain, liver, spleen, adrenals, kidneys and stomach. The residence time in these organs was calculated and radiation dose was estimated using OLINDA software. The radiation dose from the CT component was computed using the software CT-Expo and measured using computed tomography dose index (CTDI) phantom and ionization chamber. As per the clinical protocol, the patients were refrained from eating and drinking for a minimum period of 4 h prior to the study. Results: The estimated residence time in males was 0.196 h (brain), 0.09 h (liver), 0.007 h (spleen), 0.0006 h (adrenals), 0.013 h (kidneys) and 0.005 h (stomach) whereas it was 0.189 h (brain), 0.11 h (liver), 0.01 h (spleen), 0.0007 h (adrenals), 0.02 h (kidneys) and 0.004 h (stomach) in females. The effective dose was found to be 0.020 mSv/MBq in males and 0.025 mSv/MBq in females from internally administered 18FDG and 6.8 mSv in males and 7.9 mSv in females from the CT component. For an administered activity of 370 MBq of 18FDG, the effective dose from PET/CT investigations was estimated to be 14.2 mSv in males and 17.2 mSv in females. Interpretation & conclusions: The present results did not demonstrate significant difference in the kinetics of 18FDG distribution in male and female patients. The estimated PET/CT doses were found to be higher than many other conventional diagnostic radiology examinations suggesting that all efforts should be made to clinically justify and carefully weigh the risk-benefit ratios prior to every 18FDG whole body PET/CT scan.
RESUMO
Background: There has been sparse description of cortical dysplasias (CDs) causing intractable epilepsy from India. Aim: Clinical retrospective study of CDs causing intractable epilepsy that underwent surgery. Materials and Methods: Fifty-seven cases of CDs reviewed (1995 till July 2006) are presented. All patients had intractable epilepsy, and underwent a complete epilepsy surgery workup (inter ictal electroencephalography (EEG), video EEG, MRI as per epilepsy protocol, SPECT {interictal, ictal with subtraction and co-registration when required}, and PET when necessary). Surgical treatment included a wide exposure of the pathology with a detailed electrocorticography under optimal anesthetic conditions. Mapping of the sensori-motor area was performed where indicated. Procedures included resection either alone or combined with multiple subpial transactions when extending into the eloquent areas. Results: Our study had 28 (49.12%) cases of isolated focal CDs, and 29 (50.67%) with dual pathology. Average age at the time of onset of seizures in our series was 7.04 years (three months to 24 years), and average age at the time of surgery was 10.97 years (eight months to 45 years). Among coexistent pathologies, one had associated MTS, 16 had coexistent gangliogliomas and 12 (dysembryonic neuroepithelial tumor) DNTs. At an average follow-up of 3.035 years (range 5-10 years), three patients were lost to follow-up. Fifty-one per cent (29/57) patients had a good outcome (Engel Grade I) and 26%(15/57) had a Grade II outcome. Conclusion: Cortical dysplasias have a good outcome if evaluated and managed with concordant electrical and imaging modalities.