Technetium-99m ethyl cysteinate dimer (ECD) brain SPECT offers information on small areas of cortical dysplasia. Imaging the cerebral cortex with SPECT rather than MRI may prove useful in the detection of functionally focal abnormalities associated with neuronal migration disorders, according to Korean researchers.
Most often, these disorders are imaged with T1-weighted, 3-D gradient-echo MRI, but this modality does not provide information on the function or status of the lesions, nor does it identify their true causes, said Dr. Young Hoon Ryu in a presentation at the RSNA conference on November 29 in Chicago. Ryu and his co-authors are from Yonsei University College of Medicine and Gachon Medical School, both in Seoul.
Neuronal migration disorders are a group of congenital nervous system malformations that affect the process in which neuroectodermic cells move from the germinal matrix to the loci. This migration pattern produces important changes in cytoarchitecture, lamination, and normal neuronal physiology, particularly in the cerebral cortex, the group stated in its official abstract.
But when a neuronal migration disorder is present, clinical features include epileptic seizures, delayed motor development, cerebral palsy, and mental retardation, Ryu said.
In this study, Ryu and his colleagues retrospectively reviewed the records of 18 children. Five of the patients had schizencephaly, four had band heterotopia, another four had lissencephaly, three had nodular heterotopia, and two had hemimegalencephaly. Clinical diagnoses included cerebral palsy, epilepsy, and mental retardation, Ryu said.
The children underwent brain MRI and Tc-99m ECD brain SPECT imaging on the same day, he said. According to the results, the SPECT scans demonstrated extensive lesions of decreased blood flow in 16 patients, spread over a larger area than detected by MRI, Ryu said. The scans of two patients with hemimegalencephaly showed increased blood perfusion.
SPECT brain scans could serve as a valuable supplementary tool to MRI because of their ability to pick up on the pathological functional status of patients with neuronal migration disorders, Ryu concluded.
These results concur with earlier studies done by Japanese researchers at Kyushu University in Fukuoka. In the Journal of Nuclear Medicine, the investigators compared FDG-PET to Tc-99m ECD SPECT for the detection of focal cortical dysplasia.
"In ECD SPECT, one lesion demonstrated hypoperfusion and one ictal hyperperfusion, while two showed no abnormalities," the Japanese researchers wrote. "All four patients underwent a cortical resection, and the microscopic examinations were consistent with those of focal cortical dysplasia" (JNM, June 1998, Vol.39:6, pp.974-977).
By Shalmali Pal
AuntMinnie.com staff writer
January 2, 2001
Copyright © 2001 AuntMinnie.com
