Forecasting motor recovery after cervical spinal cord injury: value of MR imaging

PURPOSE

To determine whether magnetic resonance (MR) imaging quantification of cervical spinal cord damage improves the prediction of motor recovery after spinal cord injury.

MATERIALS AND METHODS

The extent of cervical spinal cord injury was measured on MR images obtained in 104 patients (aged 17-70 years) within 72 hours of spinal cord injury. The effects of hemorrhage and edema length on motor outcome were examined for at least 12 months.

RESULTS

Patients with spinal cord hemorrhage had significantly lower upper and lower extremity motor scores at the time of injury and at 12 months than did patients without hemorrhage (P < .001). There was little recovery of lower extremity function even in patients without hemorrhage. Upper extremity motor function improved significantly in all patients (P < .001); patients without hemorrhage showed the largest improvements. The motor recovery rates for patients without hemorrhage were 0.74 (upper extremities; range, 0-1) and 0.55 (lower extremities; range, 0-1); those for patients with hemorrhage were 0.31 (range, 0-1) and 0.091 (range, 0-1). Stepwise multiple regression analyses indicated that MR information on hemorrhage and the length of edema increases the ability to predict clinical outcome by 16%-33% over that with initial clinical scores alone.

CONCLUSION

An initial MR imaging evaluation of the spinal cord after spinal cord injury provides supplemental prognostic information on the recovery of motor function in the upper and lower extremities.

Performance of neuroradiologic examinations by nonradiologists

PURPOSE

To determine the level of participation by nonradiologists in performing neuroradiologic examinations.

MATERIALS AND METHODS

Medicare part B claims data from fiscal year 1992 were analyzed for CPT (current procedural terminology) codes related to computed tomography (CT) and magnetic resonance (MR) imaging of the brain, head and neck, and spine, as well as myelography, angiography, and diskography. Data were tabulated by place of service (hospital-based vs freestanding imaging centers) and by medical specialty.

RESULTS

Among 363,224 Medicare claims for CT and MR imaging of the brain, head and neck, and spine, 91% of the examinations were performed in hospitals and 9% in offices or freestanding centers; 98% of studies were interpreted by a radiologist. The largest share of radiology billing by nonradiologists was from office-based or freestanding imaging centers (9%), versus 2% at hospital-based facilities.

CONCLUSION

Radiologists perform the vast majority of neuroradiologic examinations. Most neuroradiologic examinations performed by nonradiologists are from neurologists at freestanding/office-based imaging centers.

Cocaine alters cerebral metabolism within the ventral striatum and limbic cortex of monkeys

The functional consequences of acute cocaine administration in nonhuman primates were assessed using the quantitative 2-[14C]deoxyglucose method. Local rates of cerebral metabolism were determined after an intravenous infusion of 1.0 mg/kg cocaine or vehicle in six awake cynomolgus monkeys (Macaca fascicularis) trained to sit calmly in a primate chair. Cocaine administration decreased glucose utilization in a discrete set of structures that included both cortical and subcortical portions of the limbic system. Glucose metabolism in the core and shell of the nucleus accumbens was decreased markedly, and smaller decrements were observed in the caudate and anterior putamen. In addition, cocaine administration produced significant decreases in limbic cortex. Metabolism was decreased in orbitofrontal cortex (areas 11, 12o, 13, 13a, 13b), portions of the gyrus rectus including area 25, entorhinal cortex, and parts of the hippocampal formation. The cortical regions in which functional activity was altered provide dense projections to the nucleus accumbens, and the decreased activity in these projections may be responsible in part of the large alterations in functional activity within the ventral striatum. Decreased metabolism also was evident in the anterior nuclear group of the thalamus, raphe nuclei, and locus ceruleus. The acute cerebral metabolic effects of cocaine in the conscious macaque, therefore, were contained primarily within a set of interconnected limbic regions, including ventral prefrontal cortex, medial temporal regions, the ventral striatal complex, and anterior thalamus. The decreased rates of glucose metabolism reported here resemble decrements found using positron emission tomography in humans. In the rat, by contrast, metabolic activity increased and changes were focused in subcortical regions. The present results represent an important expansion of the neural circuitry on which cocaine acts in the monkey as compared with the rat, and this in turn implies that cocaine affects a broader spectra of behaviors in primates than in rodents.

MR of malignant optic glioma of adulthood

A case of malignant optic glioma of adulthood is imaged in its early and late stages with high-resolution MR. The images show the mass to arise from the right optic nerve before invasion of the optic chiasm.

MR imaging in the diagnosis of intramedullary spinal cord diseases that involve specific neural pathways or vascular territories

Prior to the advent of MR imaging, the internal architecture of the spinal cord could not be directly imaged. The solution of many technical problems (e.g., respiratory motion, cardiac and CSF pulsation, inadequate spatial resolution) has provided the opportunity for an increasingly refined analysis of intramedullary lesions. This article begins with a brief review of the results of high-resolution MR imaging studies of the cadaveric spinal cord. The article then focuses on MR imaging in the diagnosis of intramedullary diseases that involve specific neural pathways or vascular territories. Lesions are categorized as degenerative, inflammatory, traumatic, or ischemic. These diseases generally have distinctive clinical findings that reflect dysfunction of particular ascending sensory tracts or descending motor tracts. The corresponding abnormalities on MR images reflect the pathologic changes that occur in the affected neural pathways. Knowledge of the appearance of these diseases on MR images allows the formation of a narrow differential diagnosis and, in many cases, the confident exclusion of neoplasm as the cause of myelopathy.

MR imaging: quality assessment method and ratings at 33 centers

PURPOSE

To outline a quality assessment method with peer review for magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Thirty-three providers in the Philadelphia area were rated on a random sample of 132 brain, 124 cervical spine, and 113 lower extremity MR imaging examinations performed during 1990. Blinded peer review was performed by panels of three subspecialty-trained academic radiologists. Technical performance, completeness, and report appropriateness of each MR imaging examination were evaluated. Aggregated scores were calculated to rate provider performance for each of the three parameters of quality.

RESULTS

Two or three panelists assessed technical performance as inadequate in 15 cases, completeness as incomplete in 58 cases, and the interpretative report as inappropriate and affecting treatment in 72 cases. Eleven providers received an unsatisfactory rating on one or more parameters of quality. The association between unsatisfactory ratings and the use of low-field-strength (< or = 0.6-T) imagers was statistically significant (P < .008).

CONCLUSION

Substantial deficiencies were identified in the performance of examinations and interpretation of MR images in the Philadelphia area in 1990. These findings indicate the need for a program to monitor quality of MR imaging.

Multiple sclerosis in the spinal cord: MR appearance and correlation with clinical parameters

PURPOSE

To determine the characteristic magnetic resonance (MR) imaging features of multiple sclerosis (MS) that affect the spinal cord.

MATERIALS AND METHODS

Sixty-eight patients underwent MR imaging of the cervical and/or thoracic spine. Plaques were analyzed for lesion length, cross-sectional area and location, signal intensity, and morphology. The clinical parameters of MS type, duration of disease, sex, and age were also correlated with these MR imaging findings.

RESULTS

One hundred twenty-four demyelinating plaques were found in these 68 patients; 38 had more than one plaque. The majority of plaques were two body segments in length or less and peripherally located, and occupied less than 50% of the cross-sectional area of the cord. Plaques associated with cord atrophy were more likely to occur with the relapsing-progressive form of MS. Cord swelling was found only in the relapsing-remitting form of MS.

CONCLUSION

Spinal cord MS plaques are characteristically peripherally located, are less than two vertebral segments in length, and occupy less than half the cross-sectional area of the cord.

Manuscript peer review at the AJR: facts, figures, and quality assessment

Concern by the government, funding institutions, and the public for quality assurance in all aspects of medical endeavors mandates critical examination of various professional activities. Although peer review is generally regarded as the best system for selecting and improving scientific papers for publication, the efficacy of this process has never been proved. Moreover, the administrative functions of the editorial staff are often poorly understood. The purpose of this article is to make peer review a the AJR less esoteric and more understandable by quantifying some of its activities. This information is then assessed as it relates to the quality of this important step in scientific publication.

MR imaging in a case of postvaccination myelitis

We describe a case of acute transverse myelitis after the administration of the recombinant form of hepatitis B vaccine. Abnormal enhancement of MR imaging accompanied residual neurologic deficit.

Vascular neoplasms and malformations, ischemia, and hemorrhage affecting the spinal cord: MR imaging findings

This essay illustrates the imaging spectrum of vascular neoplasms and malformations, ischemia, and hemorrhage affecting the spinal cord. Most of these abnormalities occur far more frequently in the brain. The goal of this essay is to provide a sound anatomic and radiologic basis for the evaluation of these diseases. Knowledge of the unique cross-sectional anatomy, blood supply, and venous drainage of the spinal cord is essential in understanding the radiographic appearance of certain vascular lesions. The superior spatial resolution of fast spin-echo pulse sequences and improvements in MR angiography have expanded the role of MR imaging in the diagnosis of spinal cord diseases. These techniques are emphasized in this essay, and potential diagnostic pitfalls are highlighted. The diseases illustrated are grouped in the categories of enlarged vessels, ischemia, and hemorrhage.

Metallic artifacts on MR images of the postoperative spine: reduction with fast spin-echo techniques

PURPOSE

To determine whether the relative insensitivity of T2-weighted fast spin-echo (FSE) techniques to magnetic susceptibility can be exploited to reduce metallic artifacts on images of the postoperative spine and, thus, improve the interpretation of the postoperative study.

MATERIALS AND METHODS

Three neuroradiologists retrospectively evaluated sagittal T2-weighted conventional spin-echo and FSE images obtained in 15 patients with metallic artifacts from various sources including drill particles from anterior cervical diskectomy, posterior fixation wires, fixation rods or plates, and an inferior vena cava filter. The amount of artifact present and whether these artifacts affected image interpretation were evaluated.

RESULTS

Among the 45 paired evaluations, the artifact was judged to be less apparent with FSE sequences in 39. In eight of 45 evaluations (18%), the interpretation of the area of interest was possible only on the FSE images.

CONCLUSION

FSE imaging, especially when performed with shorter echo spacing, increases the amount of T2-weighted information in the presence of metallic artifact because it decreases magnetic susceptibility effects.

Superior sagittal sinus thrombosis in the presence of idiopathic bilateral internal jugular vein stenosis

Cerebral venous outflow obstruction and anomalies in cerebral venous circulation predispose to dural sinus thrombosis. This case report illustrates the magnetic resonance and angiographic findings in a patient who had superior sagittal sinus thrombosis secondary to idiopathic bilateral internal jugular vein stenosis, a previously unrecognized entity. The findings suggest that bilateral stenosis of the internal jugular veins at their junction with the innominate veins causes obstruction to cerebral venous outflow leading to dural sinus thrombosis.

A modality-specific somatosensory area within the insula of the rhesus monkey

Response properties of neurons in the monkey's granular insula (Ig) were examined with somatic, auditory, visual, and gustatory stimuli. Results indicate that a major portion of Ig is a somatic processing area exclusively, with units that have large and often bilateral receptive fields, consistent with the view that this area serves as a higher-order, modality-specific link in the somatosensory-limbic pathway.

Magnetic resonance imaging related to neurologic outcome in cervical spinal cord injury

The purpose of this study was to examine the relationship between the initial intramedullary hemorrhage, as seen by magnetic resonance imaging (MRI), and the neurologic deficit and eventual neurologic outcome of acute cervical spinal cord injured subjects. MRI and motor assessments were performed on 24 subjects with motor complete (Frankel A & B) and incomplete (Frankel C & D) injuries. Recovery was determined by evaluating an initial and a final motor power following spinal cord injury (SCI), as defined by the manual muscle test (grade 1-5) and motor index score (MIS). Results showed that all 15 subjects having hemorrhage had motor complete injuries (Frankel A & B). Sixteen percent of the muscles in the upper extremities and 3% of the muscles in the lower extremities in these 15 subjects improved to a grade of > or = 3/5 at the final evaluation post-SCI. In comparison, of the nine subjects not having hemorrhage, eight had motor incomplete injuries (Frankel C & D) and had 73% and 74% of muscles improving in the upper and lower extremities, respectively. In addition, a change in MIS from initial to final evaluations showed a significant difference between subjects with hemorrhage and subjects without hemorrhage (upper extremities: p = .002 and lower extremities: p = .0001). In conclusion, the initial MR image and neurologic assessment correlated with motor power recovery.

Abnormalities of the posterior inferior cerebellar artery: MR imaging findings

The purpose of this essay is to review the normal MR appearance of the posterior inferior cerebellar artery (PICA) and to illustrate the MR findings of representative PICA abnormalities. Because of beam-hardening artifacts, the lower posterior fossa is difficult to evaluate with CT. MR imaging is not hampered by these artifacts. Moreover, the superb sensitivity of MR and its multiplanar imaging capability permit excellent diagnostic accuracy in this region. The PICA is well suited for evaluation on routine MR images, particularly because of the inherent contrast (signal void) of large arteries due to rapid flow. MR imaging has greatly improved our ability to noninvasively diagnose abnormalities of cerebral blood vessels and their resultant manifestations. Some of the diseases that affect the PICA include neoplasms, aneurysms, arteriovenous malformations, and occlusions. The MR images in this essay illustrate the normal appearance of the PICA, as well as these pathologic features. T1-weighted (e.g., 600/15 [TR/TE]), proton density-weighted (e.g., 2000/20), and T2-weighted (e.g., 2400/80) MR images were obtained in axial, sagittal, and coronal planes. The PICA can be evaluated with MR angiography also, although the relatively small size and tortuosity of the artery may preclude adequate visualization.

Lesions causing a mass in the medial canthus of the orbit: CT and MR features

Few detailed radiologic articles treat the medial canthus as a "compartment" of the orbit. Nasal stuffiness and epiphora (excessive tearing) are frequent clinical manifestations of diseases involving the medial canthus of the orbit. Although some lesions can be adequately evaluated by clinical examination, imaging may show unsuspected deep extensions of the abnormality. CT has traditionally been the imaging method of choice because of the inherent contrast between structures in this region and its superb depiction of bone detail (Fig. 1). MR imaging can be useful in detecting subtle marrow invasion caused by lesions extending beyond the confines of the medial canthus (e.g., frontal bone, maxilla). In this pictorial essay, we illustrate the CT and MR appearances of diseases that can manifest as a medial canthal mass and provide practical differential diagnoses. Lesions can be inflammatory, neoplastic, or developmental in origin. Moreover, these lesions can result from abnormalities in the adjacent nasolacrimal apparatus, orbit, paranasal sinuses, and nasal cavity, or they can reflect an underlying systemic illness.