Magnetic Resonance Imaging Scan Findings Research Articles

Technetium 99mTc-HMPAO SPECT in Children and Adolescents With Neurologic Disorders

We evaluated regional cerebral blood flow with technetium 99mTc hexamethylpropyleneamineoxime single photon emission computed tomography (SPECT) in 20 children and adolescents with neurologic dysfunction of varied etiology and abnormal electroencephalograms (EEGs). All patients were also examined with computed tomography (CT) and magnetic resonance imaging (MRI). Abnormal perfusion was found in 17 (85%) of 20 SPECT scans. Abnormal CT or MRI scans were noted in nine (45%) and in 10 (50%) of 20 cases, respectively. In eight (73%) of 11 cases with normal CT scans and in seven (70%) of 10 with normal MRI scans, the SPECT scan was abnormal. Abnormal regional cerebral blood flow on SPECT scans correlated better with EEG abnormalities than with neurologic examination or CT or MRI scan findings. We conclude that in children and adolescents with a spectrum of neurologic diseases and abnormal EEGs, abnormalities of brain structure or function are more likely to be documented by SPECT than by CT or MRI scans. SPECT findings correlate well with the location and type of EEG abnormality.

Occult Vascular Malformations of the Optic Chiasm: Magnetic Resonance Imaging Diagnosis and Surgical Laser Resection

Angiographically occult vascular malformations of the optic nerve and chiasm are extremely rare. Before the advent of magnetic resonance imaging (MRI), it was difficult to diagnose these lesions preoperatively. We report MRI scan findings of optic chiasm cavernous angiomas in two patients with chiasmal syndrome. MRI was useful in localizing the vascular malformation and delineating its characteristics, especially chronic hemorrhage. One patient underwent biopsy of the lesion. The other patient underwent complete microsurgical resection of the malformation with the carbon dioxide laser with preservation of vision. Occult vascular malformations of the optic nerve and chiasm may be a more common cause of visual deterioration than previously recognized. The MRI scan is the imaging modality of choice for diagnosing and following these lesions. In certain patients, these vascular malformations may be amenable to complete surgical removal with stabilization or improvement of visual function.