Prospective observations of 100 high-risk neonates by high-field (1.5 Tesla) magnetic resonance imaging of the central nervous system: I. Intraventricular and extracerebral lesions.

The results of observations of the first 100 neonates at the University of Texas Health Science Center (Houston) who received magnetic resonance imaging of the central nervous system by means of a high-field image (1.5 T) are reported. All were assessed prospectively to be at risk neurodevelopmental delay. This first report specifically addresses the appearance of primarily hemorrhagic intracranial lesions, including intraventricular hemorrhage (n = 28), and extracerebral lesions, which include 3 cases of venous sinus thrombosis (n = 20). The signal intensities of hemorrhage underwent a characteristic evolution with time with only minor variations in the study group. Magnetic resonance imaging detected direct evidence of hemorrhage for up to 2 months, but hemosiderin was detected as a late indicator of hemorrhage for up to 9 months. Magnetic resonance imaging was equal in benefit to head ultrasonography and computed tomography for the diagnosis of intraventricular hemorrhage, but magnetic resonance imaging was also able to approximate the time of onset of hemorrhage. Magnetic resonance imaging was superior for the evaluation of extracerebral hemorrhage; ultrasonography failed to detect any of these lesions and computed tomography detected only 3 of 7. Short-term neurological abnormality was assessed, but the ability of magnetic resonance imaging to predict long-term neurodevelopmental delay is unknown and is the subject of an ongoing project.

Prospective observations of 100 high-risk neonates by high-field (1.5 Tesla) magnetic resonance imaging of the central nervous system. II. Lesions associated with hypoxic-ischemic encephalopathy.

One hundred neonates determined prospectively to be at risk for neurologic handicap underwent magnetic resonance imaging with a high-field (1.5 T) imager. Thirty-three demonstrated a total of 37 lesions consistent with hypoxic-ischemic encephalopathy, including periventricular leukomalacia (n = 12), basal ganglia hemorrhage (n = 5), multicystic encephalomalacia (n = 5), and focal parenchymal hemorrhage (n = 15). Diagnoses by ultrasonography and computed tomography were compared with those by magnetic resonance imaging in 29 and 17 infants, respectively. Ultrasonography agreed more frequently with magnetic resonance imaging than did computed tomography. Ultrasonography detected 79% of lesions demonstrated by magnetic resonance imaging whereas computed tomography detected only 41%. Periventricular leukomalacia was seen most often in preterm infants, basal ganglia hemorrhage and multicystic encephalomalacia primarily occurred in term infants, and focal parenchymal hemorrhage occurred at all gestational ages. Basal ganglia hemorrhage and multicystic encephalomalacia were strongly associated with histories of perinatal asphyxia, seizures, and early abnormal neurological status. All infants with basal ganglia hemorrhage (5/5) and multicystic encephalomalacia (5/5) and the majority with periventricular leukomalacia (9/12) and focal parenchymal hemorrhages (9/15) had developmental abnormalities at discharge.

The neuroradiology of visual disturbances.

The neuroradiology of visual deficits has advanced dramatically in recent years. Plain film evaluation of the orbit and face remains useful in the emergency room for the evaluation of trauma. High-resolution coronal CT remains the method of choice in the assessment of serious injury to the orbit and in cases of penetrating metallic foreign body. The contrast-enhanced orbital CT provides useful information in cases of tumor and infection and when the bones of the face or skull are involved. MRI has largely replaced CT in the search for brain infarct, brain tumor, and cerebral inflammatory and demyelinating processes. MRI is the study of choice in all cases of sellar and parasellar disease. It offers high-resolution images in any plane. GTPA enhancement has provided additional information from MRI without significant risk. The final selection of an imaging modality should be based upon the clinical presentation and any physical limitations of the patient.

Acute spinal cord injury. A study using physical examination and magnetic resonance imaging.

Magnetic resonance imaging (MRI) was performed on 37 patients with acute spinal injury using T1- and T2-weighted images. Three different types of MRI signal patterns were detected in association with these spinal cord injuries. A classification was developed using these three patterns. Type I, seen in ten (27.0%) of the patients, demonstrated a decreased signal intensity consistent with acute intraspinal hemorrhage. Type II, seen in 16 (43.2%) of the patients, demonstrated a bright signal intensity consistent with acute cord edema. Type III, seen in three (8.1%) of the patients, demonstrated a mixed signal of hypointensity centrally and hyperintensity peripherally consistent with contusion. The remaining eight patients had normal cords by MRI. All 37 patients had an admitting neurologic assessment and classification of their spinal injury according to the Frankel classification and the Trauma Motor Index (TMI). At an average of 12.1 months postinjury, their neurologic function was reassessed. Patients with Type I patterns showed no improvement in their Frankel classification and minimal improvement in their TMI, 32.1 to 42.4. In comparison, all of the Type II and III patterns improved at least one Frankel classification. The Type II TMI increased from 70.8 to 91.9 and Type III from 37.3 to 75.7. This preliminary report indicates a distinct correlation between the pattern of spinal cord injury as identified by MRI and neurologic recovery. It appears that the ability of MRI to aid in examination of the condition of the spinal cord will offer a means of predicting neurologic recovery following acute spinal cord injury.

MR imaging of hyperacute intracranial hemorrhage in the cat.

Hyperacute intracerebral hematomas were successfully created in five cats by injecting a prepared blood sample in which the oxygen (O2) saturation ranged from 0-80%. T1- and T2-weighted spin-echo sequences and T2-weighted gradient refocused scans were obtained 2.5-10 hr after injection on a 1.5-T imaging system. Detailed histology or electron microscopy was performed on each brain to confirm the presence of intact red blood cells in a retracted clot matrix. Areas of the hematoma were hypointense relative to brain in all five cats on the gradient refocused scans. The hematoma was isointense relative to brain on the T1- and T2-weighted spin-echo scans in all cats except one, which suffered a seizure/respiratory arrest and died during the scanning procedure. Portions of the hematoma in this animal had a hypointense T2-weighted signal and a hyperintense T1-weighted signal, which corresponded to the predicted MR properties of intracellular methemoglobin. We hypothesize that acute (less than 10 hr old) hematomas that contain virtually 100% intracellular deoxyhemoglobin may not appear hypointense relative to brain on T2-weighted scan sequences at 1.5 T unless surrounding tissue hypoxia and/or anoxia promote additional changes, one of which may be the formation of intracellular methemoglobin.

Transverse sinus thrombosis in newborns: clinical and magnetic resonance imaging findings.

Neonatal transverse sinus thrombosis (TST) is considered a rare and severe sequela of birth injury. Clinical descriptions of this entity are few since most published series are postmortem studies. The advent of magnetic resonance imaging (MRI) allows recognition of TST ante mortem. We describe 4 full-term infants with distinct clinical and neuroradiological features indicative of TST, which we suggest may be relatively common, with a wide spectrum of severity, including favorable outcome.

Cervical spine MR imaging using multislice gradient echo imaging: comparison with cardiac gated spin echo.

Forty-one patients with suspected cervical spine disorders were studied using multislice gradient echo imaging (GE) technique, with a 1.5-T system. The images were compared to cardiac-gated spin echo (CGSE) images in the diagnosis of suspected cord and spinal disorders. Images were graded for ability to detect cord lesion, cord-CSF contrast, CSF-bone contrast and contrast between CSF and extradural abnormality. The signal-to-noise ratio and contrast-to-noise ratio were used to compare images. There was 44% decrease in contrast between cord lesion and normal cord on GE when compared to CGSE, except for spinal cord hemorrhage. There was a 40% improvement between bone and CSF contrast on GE compared to CGSE. GE images were significantly better qualitatively as well as quantitatively in the detection of extradural lesions. This effect was more marked in axial plane where CGSE images are extremely suboptimal. CGSE images are better than GE for spinal cord lesions, while GE are superior in the diagnosis of degenerative disease in the cervical spine.

High-resolution MR imaging of juxtasellar meningiomas with CT and angiographic correlation.

The purpose of this study was to compare the relative merits of MR imaging, CT, and angiography in the preoperative evaluation and postoperative follow-up of patients with juxtasellar meningiomas. High-resolution MR studies in nine patients with juxtasellar meningiomas were evaluated and compared with CT and angiography. The techniques were compared for the evaluation of suprasellar, parasellar, and intrasellar extension, as well as for vascular displacement or encasement, postoperative recurrence or residual calcification, and bone changes. MR provided additional information considered significant by the neurosurgeon when compared with CT, and MR was considered superior to CT in the juxtasellar area. Although MR does not obviate angiography, in many cases angiographic findings were predictable by MR.

1.5-T MR imaging of pituitary microadenomas: technical considerations and CT correlation.

Thirty-seven patients with suspected pituitary tumors were evaluated prospectively with MR imaging at 1.5 T. MR detected a microadenoma at its correct location in all eight patients who underwent transsphenoidal surgery, while CT showed a focal abnormality in the correct location in only four of the eight patients. In patients who were clinically and endocrinologically considered to harbor a microadenoma, MR detected a focal pituitary signal abnormality in 83% and CT demonstrated a focal density abnormality in 42%. Infundibular displacement, focal gland convexity, and sellar-floor abnormality were seen equally well with CT and MR. MR imaging protocol included sagittal T1-weighted spin-echo, coronal inversion-recovery, and coronal spin-echo or cardiac-gated spin-echo images. Although inversion-recovery images were superior in detecting focal pituitary lesions, some microadenomas were better seen on T2-weighted images. Cardiac-gated spin-echo images showed focal pituitary lesions better than ungated images did. Our technique demonstrates MR's superior sensitivity to CT in detecting a pituitary microadenoma.

MR imaging of transverse/sigmoid dural sinus and jugular vein thrombosis.

Magnetic resonance (MR) imaging was performed on six patients with thrombosis involving the transverse/sigmoid sinus and jugular bulb/vein. Venographic confirmation was obtained in five cases. Thrombi were characterized by increased intraluminal signal on all planes of section and pulse sequences. The change in signal intensity from first to second echo for thrombi was qualitatively less than that found with slow flow. Partial thrombosis in one case was seen as a ring pattern of central intermediate intensity corresponding to the thrombus, surrounded by a peripheral ring of signal void related to flowing blood. The MR findings closely correlated with venography in predicting thrombosis. Evidence of thrombi was not available from CT. Magnetic resonance is well suited for the diagnosis of occlusive disease of the dural venous sinus and jugular bulb.

Acute spinal cord injury: MR imaging at 1.5 T.

Thirty-seven magnetic resonance (MR) imaging studies were performed with a 1.5-T magnet and surface coils in 27 patients with suspected spinal cord injuries. Imaging was performed 1 day to 6 weeks after injury. Cord abnormalities were seen with MR in 19 patients, while skeletal and/or ligamentous injuries were seen in 21 (78%). Three types of MR signal patterns were seen in association with cord injuries. Acute intraspinal hemorrhage was seen in five patients with cord injuries and demonstrated decreased signal intensity on T2-weighted images obtained within 24 hours of injury. Cord edema and contusion had high signal intensity on T2-weighted images and were observed in 12 cases with cord injury. Neurologic recovery, determined in 16 patients, was insignificant in patients with intraspinal hemorrhage; however, patients with cord edema or contusion recovered significant neurologic function. MR at 1.5 T is extremely useful in the diagnosis of acute cord injury and also demonstrates potential in predicting neurologic recovery.

Benign pleomorphic adenomas of the salivary glands: surface coil MR imaging versus CT.

High resolution magnetic resonance (MR) imaging of three salivary gland tumors was performed at 1.5 T and compared with CT. Two of the three tumors were well seen on CT. However, one required CT sialography to separate tumor from the remaining parotid parenchyma, and, in the other, soft tissue invasion could not be excluded on the basis of CT. Magnetic resonance imaging demonstrated sharp tumor margins with no evidence of invasion. All three tumors were pathologically proven benign pleomorphic adenomas confirming the MR findings. On T2 weighted images, the two large adenomas demonstrated inhomogeneity that was not observed on CT.

Potential pitfalls of magnetic resonance imaging in the diagnosis of avascular necrosis.

Magnetic resonance (MR) imaging and radionuclide (RN) bone scans were performed in two patients with collagen vascular disease (CVD) to evaluate hip pains. In both patients RN bone scans demonstrated decreased radioactivity in the femoral heads, whereas, MR imaging was normal. Because early changes of avascular necrosis (AVN) frequently present as decreased radioactivity in the femoral head, special attempts were made to detect this decreased activity using pinhole collimator imaging. The diagnosis of AVN was confirmed surgically by venous pressure measurements. Abnormal RN bone scans representing decreased flow due to vasculitis in patients with CVD, may be more sensitive in the diagnosis of AVN before structural changes can be detected on MR studies.

Abnormalities of the neonatal brain: MR imaging. Part I. Intracranial hemorrhage.

The authors prospectively evaluated 82 neonates, ranging in gestational age from 29 to 44 weeks postconception, with magnetic resonance (MR) imaging at 0.6 T. Twenty-two cases of hemorrhage in 15 infants were identified. Ultrasound (US) and computed tomography (CT) were superior to MR in the first few days after parenchymal hemorrhage, since at this time lesions were apparent on only T2-weighted images. After the first 3 days, MR was the single best modality because (a) hemorrhage on CT became imperceptible in the 2d week, whereas the high signal of hemorrhage on MR persisted for 2-11 weeks; (b) MR permitted rough dating of hemorrhage according to changes in signal intensity; and (c) MR was superior in identifying subdural or epidural hemorrhage. Because of the nonspecificity and restricted field of view of US and the inability of CT to depict hemorrhage after 7-10 days, the authors conclude that MR significantly improves the detection of intracranial hemorrhage in neonates.

Abnormalities of the neonatal brain: MR imaging. Part II. Hypoxic-ischemic brain injury.

Eighty-five infants, 82 of whom were 29-44 weeks postconceptional age, were imaged with a 0.6-T magnet. Eight infants had cerebral infarction. In premature neonates with very water, low-intensity white matter on T1-weighted images, ultrasound was better than both computed tomography and magnetic resonance (MR) imaging in depicting parenchymal changes of infarction or edema. However, after 37 weeks gestation, MR imaging was superior. Cerebral atrophy, present in seven infants, was consistent with subarachnoid space widths of 7 mm or more, or subarachnoid space widths of 5-6 mm with ventricular/brain ratios of 0.36 or greater. Delayed myelination was seen in a total of 18 infants with histories of hypoxic-ischemic insult. MR imaging shows promise in the neonatal period. It facilitates recognition of infarcts in full-term infants and may be used to predict abnormal neurologic outcome in infants who have initial delayed myelination.

Magnetic resonance imaging and computerized tomography in relation to the neurobehavioral sequelae of mild and moderate head injuries.

Twenty patients admitted for minor or moderate closed-head injury were studied to investigate the relationship between magnetic resonance imaging (MRI) and neurobehavioral sequelae. The MRI scans demonstrated 44 more intracranial lesions than did concurrent computerized tomography (CT) scans in 17 patients (85%); most of these lesions were located in the frontal and temporal regions. Estimates of lesion volume based on MRI were frequently greater than with CT; however, MRI disclosed no additional lesions that required surgical evacuation. Neuropsychological assessment during the initial hospitalization revealed deficits in frontal lobe functioning and memory that were related to the size and localization of the lesions as defined by MRI. Follow-up MRI and neuropsychological testing at 1 month (13 cases) and 3 months (six cases) disclosed marked reduction of lesion size paralleled by improvement in cognition and memory. These findings encourage further investigation of the prognostic utility of MRI for the clinical management and rehabilitation of mild or moderate head injury.

Developmental features of the neonatal brain: MR imaging. Part I. Gray-white matter differentiation and myelination.

To establish the normal appearance of the neonatal brain, 51 neonates, 29-42 weeks postconception, underwent magnetic resonance (MR) imaging with a 0.6-T magnet in a prospective study. T1-weighted images were used to devise stages for the appearance of gray-white matter differentiation and extent of myelination. The results show that from 29 to 42 weeks postconception, changes in gray-white matter differentiation and myelination follow the stages in an orderly and predictable fashion. Changes in white matter intensity appear related to progressive decrease in brain water content. Myelination progresses cephalad from the brain stem at 29 weeks to reach the centrum semiovale by 42 weeks. Delayed myelination, defined as the absence of myelin in the corona radiata by 37 weeks, was seen in nine infants with complicated perinatal courses. Awareness of these developmental features should help to minimize misinterpretation of normal changes in the neonatal brain and lead to earlier detection of pathologic conditions, both with MR imaging and computed tomography.

Developmental features of the neonatal brain: MR imaging. Part II. Ventricular size and extracerebral space.

Magnetic resonance (MR) imaging with a 0.6-T magnet was performed on 51 neonates, aged 29-42 weeks postconception. In 45 neonates, the ventricular/brain ratio (V/B) at the level of the frontal horns and midbody of the lateral ventricles ranged from 0.26 to 0.34. In six other infants a V/B of 0.36 or greater was associated with either cerebral atrophy or obstructive hydrocephalus. The width of the extracerebral space measured along specified points varied little in the neonatal period and ranged from 0 to 4 mm in 48 infants. Extracerebral space widths of 5-6 mm were seen in three other infants with severe asphyxia. Prominence of the subarachnoid space overlying the posterior parietal lobes is normal in neonates and should not be confused with cerebral atrophy. The authors conclude that V/B ratios of 0.26-0.34 and extracerebral space widths of 0-4 mm represent the normal range, and that neonates whose measurements exceed these values should be followed up.

Magnetic resonance imaging in the diagnosis of the cranio-cervical manifestations of the mucopolysaccharidoses.

Sixteen magnetic resonance (MR) studies were performed in eight patients with mucopolysaccharidosis (MPS). In patients with Hunter, Hurler, and Scheie syndromes, multiple areas of increased signal intensity were noted in the periventricular white matter. Computerized tomography (CT) frequently failed to demonstrate these white matter lesions. Other findings included spinal cord compression, hydrocephalus and airway obstruction due to soft tissue thickening around pharynx. In patients with Morquio syndrome, cervical spine dislocation, spinal cord compression and hydrocephalus were diagnosed by MR. MR was superior compared to CT, plain films and plain tomography, as the narrowing caused by bone and soft tissue changes were better seen with MR. Our experience suggests that MR should be the primary imaging modality for the detection of cranial abnormalities in patients with MPS. High resolution surface coil imaging may be preferable to invasive procedures such as myelography and CT with intrathecal contrast agents for the evaluation of cervical spine disease.