Kaoru Konishi

Normal brain maturation in MRI

Normal brain maturation was evaluated with MR imaging of 36 neonate to 2-year-old patients. The myelination process in centrum semiovale was quantitatively assessed in 50 6-months- to 15-year-old children, and 40 adults aged 16-60 years. Imaging was performed with a 0.35 T superconducting MR unit using spin echo pulse sequences. On T1-weighted images, three stages of maturation could be observed: (1) neonates within 1 month; (2) 1-6 months of age; and (3) adult configuration after 6-7 months of age. Also on T2-weighted images three maturation stages could be defined: (1) neonatal pattern in the first 6 months of life; (2) signal inversion between 6-18 months; and (3) adult appearance after 18 months. Thus, the combination of T1- and T2-weighted images could lead us to the assessment of brain maturation in infants younger than 2 years. The myelination process in centrum semiovale was fast during the first 3 years followed by slow progression until 20-30 years of age.

Superior sagittal sinus thrombosis in neonates

Three neonatal patients with superior sagittal sinus thrombosis are reported. The neurologic signs were bulging of the anterior fontanel and clonic hemi-convulsions. Neonatal polycythemia was believed to be an etiologic factor in two patients. Computed tomography revealed massive edema with slit-like ventricles in two patients. Increased density of the torcular Herophili and straight sinus also were demonstrated in two patients. The diagnosis of superior sagittal sinus thrombosis was confirmed by cerebral angiography in one patient and by digital subtraction angiography in the other two patients. Digital subtraction angiography appears to offer a definite advantage in the diagnosis of cerebral sinus thrombosis in the neonatal period.

Magnetic Resonance Imaging in Infantile Spasms: Effects of Hormonal Therapy

Summary: Magnetic resonance imaging (MRI) was per‐formed on five patients with infantile spasms who were treated with relatively low doses of adrenocorticotrophic hormone (ACTH) to study the extent of brain shrinkage induced by ACTH therapy. MRI prior to ACTH therapy revealed periventricular hyperintensity (PVH) areas and poor myelination in four patients. In one case, MRI per‐formed 2 days after initiation of ACTH therapy also showed PVH and poor myelination. Brain shrinkage was observed 2 weeks after initiation of ACTH therapy. The most impressive follow‐up finding upon MRI was the de‐crease in PVH found in four patients. The differentiation between myelinated white matter and surrounding cortex became poorer in three cases. Cortical atrophy progressed in all patients but ventricular dilation progressed in only one patient. At the end of ACTH therapy, ventricular dilation progressed in all cases. These findings suggest that loss of water not only from periventricular white matter but also from cortex is the main etiological factor of brain shrinkage induced by ACTH.

Periventricular hyperintensity detected by magnetic resonance imaging in infancy

Twenty-one infants younger than 12 months of age were diagnosed as having periventricular hyperintensity (PVH) on T2-weighted magnetic resonance imaging. Ten infants had experienced neonatal asphyxia, 6 intracranial hemorrhage, 2 bacterial meningitis, and 3 apnea. PVH was classified according to its extent. Round foci of PVH surrounding the frontal and occipital horns of the lateral ventricles were observed in 4 infants (PVH pattern I). Continuous PVH was observed in 17 infants (PVH patterns II and III). Fourteen infants with continuous PVH had spastic diplegia or quadriplegia. Developmental delay was demonstrated in 15 infants with continuous PVH. No PVH pattern I infants had cerebral palsy; only 1 such infant had mild developmental delay. Our study suggests that the extent of PVH reflects the severity of brain damage in neonates with cerebral injuries.

Developmental features of the brain in preterm and fullterm infants on MR imaging

Normal development and maturation in pre- and postnatal periods were studied using MR imaging. For this purpose, we performed MR imaging at a postmenstrual age of 37-44 weeks in both low-risk preterm and fullterm infants and assessed the myelination pattern and the dimension of the pituitary gland, corpus callosum, pons and cerebellar vermis. There were no differences in stages of myelination and the size of these structures in both groups. MR imaging was also performed in infants with various cerebral injuries. Focal or diffuse areas of hyperintensity on T2-weighted images and delayed myelination were the commonly observed abnormal findings in these infants.

MR imaging of myopathy

Magnetic resonance imaging was performed in 8 patients with muscle disease and 6 normal controls. High intensity areas of varying dimensions were found in thigh muscles of the patients with progressive muscular dystrophy (PMD) and congenital myopathy. Shortened T1 and prolonged T2 values with disease progression were characteristic. The T1 values were variable and prolonged, T2 values were more characteristic of progressive muscular degeneration. The T1 value may help to detect the early stage of PMD. Magnetic resonance imaging is useful in detecting the muscle lesions in PMD and essential for selection of a biopsy site.

Septo-optic dysplasia with infantile spasms

A 21-month-old boy with septo-optic dysplasia and infantile spasms is reported. Eighteen hours after birth he had generalized convulsions, dyspnea, and hypoglycemia which were followed by recurrent clonic seizures despite administration of phenobarbital and valproic acid. At 16 months of age he had hypoglycemia and apnea attacks during varicella infection. At 19 months of age left hemiconvulsions and left hemiparesis occurred; his mental and motor development, which had been delayed but progressive, deteriorated. Tonic spasms appeared at 21 months of age and electroencephalography revealed multifocal spikes. At 27 months of age electroencephalography disclosed hypsarrhythmia. Cranial computed tomography depicted brain atrophy, right microphthalmia, and intact septum pellucidum. Magnetic resonance imaging demonstrated hypoplasia of the corpus callosum and a small pituitary gland. Coloboma of the right optic disc was detected. Physical examination revealed short stature, left hemiparesis, micropenis, and cryptorchidism. Endocrinologic loading tests revealed hypofunction of the hypophysial anterior lobe.

Magnetic resonance imaging in preterm infants

Magnetic resonance imaging was performed in 9 preterm infants at 37-43 weeks postmenstrual age. They all were born at 26-35 weeks gestation. Myelination was graded according to its most cephalic location. Myelination pattern 2 (myelination observed in the posterior limb of the internal capsule and adjacent structures of the thalamus and lenticular nucleus) was demonstrated in 2 infants, pattern 3 (myelination of the corona radiata) in 3 infants, and pattern 4 (myelination of the centrum semiovale) in 4 infants. Bilateral low intensity areas were found on T1-weighted images in 7 infants and a ribbon-like, high intensity was observed in 5. These findings revealed a wide variety of magnetic resonance imaging appearance in apparently normal preterm infants. Caution is needed in interpreting the pathologic nature of such features in preterm infants during the perinatal period.

Growth patterns of the normal pituitary gland and in pituitary adenoma.

The growth pattern of the pituitary gland of 86 infants, children and adolescents without pituitary or hypothalamic dysfunction was studied with sagittal magnetic resonance imaging. Postnatally the gland grew rapidly, reaching a plateau at almost three years after birth, and growing rapidly again between the age of 10 to 13 years. Pituitary gland area showed a similar growth pattern to gland height. The pituitary glands of seven patients with pituitary adenomata were also examined. All had convex upper‐gland margins, with height and area significantly greater than those of normal controls of the same age.

Assessment of local cerebral blood flow in neonates with N-isopropyl-P-[123I]iodoamphetamine and single photon emission computed tomography

Local cerebral blood flow was measured in 10 high-risk infants with neonatal episodic neurological events at 41-44 post-conceptional weeks using N-isopropyl-p-[123I]iodoamphetamine (IMP) and single photon emission computed tomography (SPECT). In 5 of the 7 infants with normal neurological outcome, prominent cerebral perfusion was found in the basal ganglia, brainstem, cerebellum, parietal white matter, and sensory motor cortex. The frontal lobes showed poor relative perfusion. In 3 infants with severe neurological deficits, SPECT demonstrated severe hypoperfusion of all parts of the brain except the basal ganglia, brainstem and sensorimotor cortex. However, MRI revealed non-specific changes, such as poor myelination and ventricular dilatation. SPECT, when performed in the first weeks of life, can be useful and may be more sensitive than MRI in predicting the occurrence of major neurological handicaps. However, because of the relatively invasive character and high cost of SPECT, SPECT should not necessarily be performed in all high-risk neonates.