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Until the development of magnetic resonance (MR) imaging there was no nondestructive technique for monitoring the pathologic response to acute spinal cord trauma. The characteristic findings of hemorrhage, necrosis, and edema have been well described in animal models. We used a 1.4-T, animal imaging system to study acute cord contusions in rats. Contusions were induced by means of extradural aneurysm clip compression, and imaging was performed 3-5 hours after injury with short and long spin-echo (SE) sequences. Animals were killed immediately after imaging, and the gross anatomic and histologic findings were correlated with image appearances. On long SE sequences edema appeared as an area of high signal intensity that extended proximal and distal to the site of contusion. At the contusion site there was focal intraparenchymal hemorrhage which had low signal intensity on T2-weighted images, presumably owing to deoxyhemoglobin. MR imaging can be used to assess pathologic changes resulting from acute cord contusion and to aid in differentiating irreversible damage (hemorrhage) from potentially reversible edema.

Three patients with dural arteriovenous malformations contiguous with the cavernous sinus had marked worsening of their neuro-ophthalmic symptoms. Such clinical deterioration has been attributed traditionally to increased blood flow through the malformations into the superior ophthalmic vein. However, arteriography in all three patients and magnetic resonance imaging (MR) in two patients demonstrated thrombosis of the entire superior ophthalmic vein. All patients subsequently underwent spontaneous, complete resolution of symptoms. This report describes a clinical syndrome of paradoxical worsening of cavernous sinus malformations and indicates that MR will aid in the management of these vascular malformations.

Fifty-nine cases in which surface coil MR imaging of the orbit was performed were reviewed. MR imaging was performed with spin-echo techniques at 1.5 T with both short repetition time/echo time (TR/TE) and long TR/TE sequences in all cases. In all patients short TR/TE images were obtained with small-diameter surface coils; long TR/TE images were usually obtained with a standard head coil. Surface coil MR appears to be an important adjunct in state-of-the-art orbital imaging. Orbital MR imaging may be most useful, providing information not available on computed tomography (CT), in identifying lesions in the orbital apex, superior orbital fissure, and optic canal; differentiating inflammatory pseudotumor from malignancy in clinically similar patients; characterizing lesions containing hemorrhage or other paramagnetic material; defining the posterior extent of optic pathway gliomas; and detecting abnormal flow in intraorbital vascular structures. CT seems to be superior to MR imaging in the evaluation of small perioptic meningiomas, especially those that are calcified.

One hundred and forty patients with cerebral neoplasms were examined in a 0.12-Tesla prototype resistive NMR proton imaging device by partial saturation technique. NMR was superior to CT in tumor and edema localization and equal to CT in tumor and edema detection. NMR, however, was not able to clearly separate tumor from edema, a separation that contrast enhanced CT achieved.

Subacute intracranial hematomas have variable appearances on high-field MR images. They are hyperintense on T1-weighted images owing to methemoglobin, but have variable intensities on T2-weighted images. Observation of the different high-field spin-echo MR intensity patterns of five subacute hematomas suggests that further subcategorization into different methemoglobin states may be possible. In particular, undiluted intracellular methemoglobin is hyperintense on T1-weighted images and markedly hypointense on T2-weighted images, undiluted free methemoglobin should be hyperintense on T1-weighted images and isointense or slightly hypointense on T2-weighted images, and dilute free methemoglobin is hyperintense on both T1- and T2-weighted images. However, it appears that certain regions of subacute hematomas may be difficult to differentiate, by intensity patterns alone, from melanotic melanomas or fat. We believe that, despite some limitations, MR is useful in dividing subacute intracranial hematomas into their respective methemoglobin states, and also that further subcategorization is possible.

Over a 6-month period, 157 patients, 89 of whom had central nervous system tumors, were examined on a prototype 0.12 T resistive nuclear magnetic resonance (NMR) imaging unit. All of the patients had computed tomography (CT), which was used as a standard to which the NMR findings were compared. Studies were done primarily by saturation-recovery technique with short repetition times. The signal intensity with saturation-recovery technique did not allow differentiation among most tumor types. Location, extent, and morphology helped to some extent in attempts at differentiation. In the multiplanar mode, NMR compared favorably to CT with regard to lesion detection. Limited early experience suggests that NMR also may detect some lesions when the CT is negative and may detect additional lesions when one or more are present. The NMR examination was well tolerated by selected patients.

Two patients treated with high dose methotrexate otrexate with citrovorum rescue (HDMTX-CF) for osteogenic sarcoma developed the acute onset of neurologic deficits. Prior to the onset of symptoms, one child suffered brief episodes of altered consciousness. Both patients developed hemiparesis and then steadily improved over 72 hours. Laboratory evaluations disclosed normal coagulation parameters and nontoxic serum methotrexate levels at onset of symptoms. Computed tomography in one child disclosed a large low absorption abnormality. This patient represents the first reported case of positive radiologic findings associated with this syndrome. The two patients recovered completely and received further HDMTX-CF without sequelae. This condition may result from transient demyelination or embolic cerebrovascular disease.

We report a case of multiple aneurysms with subarachnoid hemorrhage in which CT was inconclusive as to the source of bleeding and in which the angiographic criteria were misleading. Magnetic resonance demonstrated a focal subarachnoid hematoma adjacent to the ruptured aneurysm.

A retrospective study of the magnetic resonance (MR) images of the lumbar spines of 13 healthy subjects and 30 patients with degenerative changes was done. In the healthy subjects, the vertebral facets, thickness of the cartilage and ligamentum flavum, signal characteristics of the bone marrow, and size of the spinal canal were studied. In the patients with degenerative changes in one of these structures, MR images in the sagittal plane were useful in demonstrating hypertrophy of the ligamentum flavum or the vertebral facets, in grading the degree of foraminal stenosis, and in measuring the sagittal diameter of the spinal cord. MR images in the axial plane facilitated detailed analysis of the facet joint and more accurate measurements of the thickness of the ligamentum flavum and spinal canal diameter. MR images were compared with computed tomography scans in 12 patients.

Gliomatosis cerebri is a rare condition characterized by diffuse overgrowth of large portions of the brain and spinal cord by glial cells in varying stages of differentiation. The tumor process is primarily an infiltrative, rather than a destructive one. Hence, pre-operative diagnosis by traditional imaging studies, including computed tomography (CT), has been difficult. Magnetic resonance imaging (MRI), with its unique sensitivity for cerebral pathology, is an ideal modality for demonstrating this lesion. We present three cases of gliomatosis cerebri in which high-field MRI clearly delineates the extent of the pathologic process.

Four dogs were immunized with a mixture of spinal cord homogenate and complete Freund's adjuvant. One of these dogs developed hyperacute allergic encephalomyelitis. Cranial computed tomography in this animal demonstrated a low absorption area in the internal capsule that corresponded to the pathologic lesion. Computed tomography scanning may be a useful tool in monitoring experimental allergic encephalomyelitis.

The sensitivity and specificity of CT and high-field MR (1.5 T) were compared in an evaluation of 30 patients with head injuries (eight acute, 15 subacute, and seven chronic). By using T1- and T2-weighted images, it was possible to detect various stages of hemorrhages and their separation from edema. In the acute category, both CT and MR showed acute hemorrhagic lesions, but only MR demonstrated coexisting chronic hematomas or small hypothalamic or brainstem infarctions. MR was far superior to CT in the detection and characterization of subacute injuries, including shearing injuries, hemorrhagic and nonhemorrhagic contusions, and subdural hematomas. In chronic injury, atrophy was demonstrated by both techniques, but only MR showed parenchymal abnormalities and old hemorrhages. Its ease in monitoring patients and its greater speed make CT the procedure of choice for the evaluation of acute cases. CT also provides information that is useful in deciding between surgery and medical management. However, the more precise anatomic depiction of MR and its sensitivity to parenchymal abnormalities make MR the key to correct prognosis in patients with subacute or chronic injury.

Cavernous sinus thrombosis is an important but difficult clinical diagnosis to confirm by most imaging modalities. 1,2 Until the advent of highfield magnetic resonance imaging (MRI), the imaging method of choice for evaluating thrombus formation in the cavernous sinus was transarterial or intravenous digital subtraction angiography. This article discusses the MRI findings in the diagnosis of cavernous sinus thrombosis. REPORT OF A CASE A 73-year-old woman noticed pain around her left eye ten days before examination. Over the next four days, her left upper eyelid drooped, and she experienced double vision. She was hospitalized elsewhere, and computed tomography (CT) showed a mass in the left anterior cavernous sinus. A cerebral arteriogram was normal. The patient was treated with systemic corticosteroids (prednisone, 80 mg/d), with no resolution of the pain or ocular motility disturbance. Five years prior to admission, the patient had an episode of painful ophthalmoplegia that was described

Thirteen patients with definite multiple sclerosis (MS), studied 16-24 months previously with magnetic resonance (MR) imaging with and without enhancement by intravenously administered gadolinium diethylenetriaminepentaacetic acid (DTPA) dimeglumine, were reexamined with a similar protocol. Assessment of enhancement and clinical activity in both studies revealed that enhancement was observed in 13 of 14 cases in which clinical activity had changed within 4 weeks of the study and thus appeared more sensitive than clinical examination in determining active disease. The 3-minute postinjection, short repetition time image (TR) was the most efficient for depicting enhancement. Enhancing lesions (active plaques) arose from previously hyper- or isointense regions on long TR images. Previously active lesions reverted to areas of iso- or hyperintensity on long TR images. Serial comparison of long TR images in this population reveals a decrease in high-intensity lesions on long TR images in some cases and an increase in others. The findings of high-intensity regions on long TR images and previously enhancing lesions both becoming isointense suggests that transient inflammatory changes with concomitant edema without demyelination and/or with significant remyelination may occur in some MS lesions. MS lesions are dynamic; both active and inactive lesions may show dramatic change on longitudinal MR imaging studies.

A single case of Wilson's hepatolenticular degeneration was imaged by computed tomography and magnetic resonance (1.5 Tesla). Findings included generalized cerebral atrophy seen both on computed tomography and magnetic resonance images. T1-weighted images revealed a slight symmetric hypointensity in the lentiform nuclei and thalamus. T2-weighted images demonstrated marked symmetric hypointensity in the lentiform nuclei. These hypointensities are ascribed to the deposition of intracellular hemosiderin (and perhaps copper), which produce heterogeneous magnetic susceptibility and preferential T2-proton relaxation. Areas of increased signal activity on T2-weighted images were also seen in areas of presumed demyelination known to occur in Wilson's disease.

Two cases of widening of the L-5, S-1 anterior epidural space after lumbar laminectomy and bilateral transverse process fusion are reported. Metrizamide lumbar epidurography was valuable in assessing this apparent widening and demonstrating that this space was normal and free of disc material. Posterior traction on the dural sac is a possible explanation for this myelographic abnormality.

Low field strength (0.12 Tesla resistive) and high field strength (1.0, 1.4, or 1.5 Tesla superconductive) magnetic resonance imagers were compared for their ability to detect central nervous system lesions. Sixteen adult patients with known lesions and three normal volunteers were studied. Contrast-enhanced computed tomography was used as the standard. The data demonstrate that imaging at high magnetic field strength is superior to low field strength imaging for the detection and delineation of lesions. This finding can be explained by the superior signal-to-noise ratio achievable at the higher magnetic field strengths. High field MR imaging was also found to outperform CT in demonstrating anatomic details and relationships. It is predicted that the use of low saturation (e.g., long TR spin echo technique) will make the gain in contrast-to-noise ratio even more significant.

Nine dogs underwent a surgically created partial obstruction of the large bowel and were then given oral barium sulfate. The residual lumen of the obstructed portion varied from 4 to 10 mm in diameter. Clinical obstruction did not develop, and all dogs passed the barium sulfate in 1 to 16 days. This limited study plus certain clinical observations would suggest that barium sulfate proximal to a partial large-bowel obstruction may not be as dangerous as commonly thought.

Seven patients presented with neonatal arteriovenous malformation and vein of Galen aneurysms. Six had a large degree of vascular steal demonstrated by cerebral angiography and all had significant parenchymal loss on initial CT. Angiographically, the steal affected the ophthalmic artery and branches of the middle and anterior cerebral arteries. Repeat CT in two patients, one of whom was untreated for 7 months, revealed pronounced atrophy. Patients with neonatal vein of Galen aneurysms present with parenchymal loss on CT which is related to vascular steal and may be progressive.

To determine the relationship between MR relaxation times and the iron content of the spleens in patients with thalassemia, we measured these parameters at 0.19 and 1.18 T in 19 thalassemic spleen specimens in vitro. The correlation was best between iron content and the dependence between the interecho interval and the 1/T2 (T2 relaxation rate) at 1.18 T(r = .9361, p less than .001). No statistically significant correlation was found between T1 and iron content at either field strength. The variation of the 1/T2 with interecho interval may be useful for measuring iron content in vivo. It supports the theory that the T2 relaxation of iron deposits occurs via cellular field gradients produced by intralysosomal granules of hemosiderin.

Twenty intracranial hematomas between 1 day and over 1 year old were imaged using magnetic resonance at 1.5 T, with T1- and T2-weighted spin-echo pulse sequences. Characteristic intensity patterns were observed in the evolution of the hematomas, which could be staged as acute (less than 1 week old), subacute (greater than 1 week and less than 1 month old), or chronic (greater than 1 month old). Acute hematomas were characterized by central hypointensity on T2-weighted images (WIs). Subacute hematomas had peripheral hyperintensity on T1-WIs and then on T2-WIs. This hyperintensity proceeded to fill in the hematoma in the chronic stage. In subacute and chronic hematomas, there was hypointensity on T2-WIs in the immediately adjacent part of the brain. On T2-WIs of acute and subacute hematomas, the nearby white matter was characterized by hyperintensity, consistent with edema. A different mechanism is proposed for each of the three characteristic intensity patterns. Two of these mechanisms increase in proportion to the square of the magnetic field magnitude.

Fifty-seven patients with hemorrhagic intracranial lesions were examined with magnetic resonance (MR) imaging at 1.5 T with use of both spin-echo (SE) and gradient-echo-acquisition (GEA) techniques to assess the clinical applications and limitations of GEA in evaluation of intracranial hemorrhage at high field strength. All GEA images were obtained with a long echo time and short flip angle to emphasize T2*-based contrast. In 30 of 61 cases, GEA images demonstrated more hemorrhagic lesions than SE images. In 14 of 61 cases, GEA images failed to depict the lesion or obscured the specific diagnosis (as depicted by SE MR imaging). The authors believe that GEA imaging in its current form has a limited but definite adjunctive role in the evaluation of intracranial hemorrhage at high field strength.

Ten patients with intracerebral metastases from malignant melanoma were evaluated with magnetic resonance (MR) imaging performed at 1.5 T using spin-echo techniques. On the basis of histopathologic findings in three of 10 cases and CT appearances in all 10 cases, three patterns were identified on analysis of MR signal intensities in both short repetition time/echo time (TR/TE) and long TR/TE spin-echo scans. In comparison to normal cortex, nonhemorrhagic melanotic melanoma appeared markedly hyperintense on short TR/TE images and isointense, mildly hypointense on long TR/TE images. Nonhemorrhagic, amelanotic melanoma appeared isointense or mildly hypointense on short TR/TE and isointense or mildly hyperintense on long TR/TE images. Hemorrhagic melanoma varied in appearance, depending on the stage of hemorrhage. Melanotic, nonhemorrhagic melanoma can be distinguished from early and late subacute hemorrhage by its signal intensity on long TR/TE images. Spin-echo MR appears to be the method of choice for diagnosing melanotic metastases.

Retinoblastoma is a highly curable tumor unless extraocular extension or metastases have occurred. Intracranial retinoblastoma metastases usually result from either contiguous or hematogenous spread and are rapidly fatal. We report two cases of pathologically proven, hemorrhagic intracranial retinoblastoma metastases and correlate magnetic resonance images with pathologic findings. Magnetic resonance with its high sensitivity and specificity for blood extravasation can document the associated hemorrhagic component of the tumor and help in the differentiation of nonmetastatic second neoplasms in retinoblastoma patients.

Cerebral aspergillosis currently occurs most frequently with disseminated aspergillosis in immunocompromised hosts. Twelve patients with cerebral aspergillosis in this setting were seen over 10 years. Underlying illnesses were renal transplantation in six cases and one case each of subacute hepatic necrosis, head trauma, glioblastoma, microglioma, and esthesioneuroblastoma. All patients were receiving high dose steroid therapy except one who had ectopic ACTH syndrome. Eleven patients were receiving broad spectrum antibiotics. All patients were febrile and developed progressive pulmonary infiltrates preceding or coincident with neurologic symptoms. Sudden onset of neurologic deficits or seizures occurred in nine of 11 clinically analyzable cases. Brainstem or cerebellar signs and symptoms were a presenting feature in three cases and were eventually seen in five cases. Cranial computerized tomography in four cases showed low absorption areas with minimal enhancement and little mass effect. Neurologic deterioration was rapid with nine of 11 patients dying within 6 days of onset. Neuropathologic examination showed multiple abscess formation in 11 cases and prominent blood vessel invasion in all cases. The sudden onset of stroke-like deficits and brainstem findings in a febrile immunocompromised host with pulmonary infiltrates suggests the diagnosis of cerebral aspergillosis. Two cases of aspergillus meningitis were also seen, one postoperatively.

Occult cerebral vascular malformations (OCVMs) have characteristic appearances on high-field magnetic resonance (MR) images. These consist of circumscribed regions of low intensity, most prominent on T2-weighted images and representing hemosiderin deposits. Interspersed within most of these lesions are multiple areas of various signal intensity patterns, which correspond to hematomas in different stages of evolution and to fibrous regions containing calcium as well as hemosiderin. Forty-six lesions were found in 19 patients (34 supratentorial and 12 infratentorial). The supratentorial lesions tended to be subcortical or periventricular. Computed tomography depicted 24 of the 46 lesions demonstrated by high-field MR. Comparison of images obtained with both low-field MR (0.12 T and 0.35 T) and high-field MR (1.5 T) revealed that high-field MR imaging was superior in depicting OCVMs. High-field MR appears to be both sensitive and specific for OCVMs and may obviate the need for possible biopsy of these lesions.

A model of radiation injury to the brain was developed in the cat. Definite radiation changes were demonstrated at magnetic resonance (MR) imaging in four of six cats. These changes consisted of high-intensity abnormalities on images obtained with a long repetition time (TR) and a long echo time (TE), which were initially noted 208-285 days after irradiation. These changes were associated with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) enhancement on short TR and inversion-recovery (IR) pulse sequences. Gd-DTPA enhancement and the high intensity on the long TR/TE images were identified at the same time and became more prominent throughout the study. Chemical-shift imaging and phosphorus spectroscopy demonstrated no notable changes despite clear-cut MR evidence of abnormalities. Sodium imaging was positive in one case. Correlation of MR and pathologic findings revealed areas of radiation necrosis and wallerian degeneration that corresponded to areas of Gd-DTPA enhancement on short TR and IR images and to areas of high intensity on long TR/TE images. Peripheral to the areas of Gd-DTPA enhancement were nonenhanced zones of high-signal-intensity abnormality on long TR/TE images, which represented regions of demyelination without necrosis. Gd-DTPA-enhanced proton imaging was the most sensitive method for detecting radiation damage in this animal model.

We studied the spectroscopic appearance of radiation-induced myelinolysis in cats to understand the characteristics of proton MR spectroscopy of demyelinating disorders. Eight cats received 5,000 rads to a 1.5 x 1.5 cm area of the right cerebral hemisphere. Eight to 9 months after irradiation, a gross area of abnormal postcontrast enhancement and/or high MR signal intensity was detected in the irradiated hemisphere of six of the eight cats. Proton spectra of a 1.0 cm3 voxel in the affected region demonstrated depressed N-acetyl aspartate/creatine-phosphocreatine and N-acetyl aspartate/choline-containing compound peak ratios compared with the contralateral non-irradiated brain in all cats. Elevated amino acid resonances in the 2.0-2.5 ppm range were not consistently seen in irradiated zones of the brain with pathologic findings of demyelination. In vivo proton MR spectroscopy may show differences between irradiated brain and nonirradiated brain even when histopathologic lesions are not apparent yet.

Appropriate spin-echo (SE) pulse sequence parameters generate magnetic resonance (MR) images with very high gray matter/white matter contrast in neonates and young infants. In these young patients, long SE sequences with a repetition time of 3,000-3,500 msec and multiple echoes with the longest echo time of 120-160 msec are employed to yield high-contrast images. A high-contrast MR image of a 1-month-old infant is presented.

Cytomegalovirus (CMV) infection is an established cause of morbidity and mortality in renal transplant recipients. CMV-seronegative (SN) recipients of allografts from seropositive donors appear to be particularly vulnerable to clinically apparent post-transplant CMV disease. Since CMV seropositivity increases with age, pediatric transplant candidates are a logical population in whom to consider establishment of pre-transplant immunity through vaccination. Results of a preliminary vaccine trial in 5 SN adult transplant candidates immunized with CMV Towne 125, an attenuated strain, are reported here. Antibody to CMV was detected by IFA 2-4 weeks after vaccination in all patients. No CMV was recovered from any patient, despite later immunosuppression. No vaccine-attributable clinical or laboratory abnormalities have occurred. Current status of vaccinees is as follows: Vaccination may offer a safe means of production of CMV antibody in renal transplant candidates at risk for CMV infection.

High field strength magnetic resonance imaging (MRI) provides a noninvasive means of evaluating patients with parkinsonism. Using strict clinical criteria, we began a prospective study of patients with Parkinson's disease (PD) and parkinsonian syndromes (PS) including progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and atypical parkinsonism (ATYP). We detected moderate to severe putaminal hypointensity more frequently in PS than in PD and controls, although putaminal hypointensity did not distinguish between MSA, PSP, or ATYP. Signal intensity in the lateral substantia nigra did not differ significantly among patients with PD, PS, or controls and was therefore not a useful MRI marker. Pars compacta width was significantly narrower in both PD and PS. Subcortical and periventricular hyperintense foci were more abundant in PD and PS than controls. Atrophy of the brainstem occurred only in patients with PS.