Spinal cord functional MRI at 3 T: gradient echo echo-planar imaging versus turbo spin echo.

The purpose of this study was to evaluate and compare turbo spin echo (TSE) with gradient echo echo-planar imaging (GE-EPI) pulse sequences for functional magnetic resonance imaging (fMRI) of spinal cord activation at 3 T field strength. Healthy volunteers underwent TSE and GE-EPI spinal fMRI. The activation paradigm comprised the temporal alternation of finger motion and rest. Pulse sequences were optimized to obtain sufficient image quality and optimal sensitivity to small T(2) or T(2)* relaxation time changes. Spinal cord activation measured by the two pulse sequences was evaluated with respect to spatial distribution of activation, signal sensitivity, and reproducibility. For the GE-EPI sequence, fMRI activation was maximal in the spinal cord segments at the levels of the fifth cervical down to the first thoracic vertebra. For the TSE sequence, fMRI measurements showed no distinct location with maximal activation. Percentage signal change and number of activated voxels were approximately twice as high for GE-EPI compared to TSE fMRI. Reproducibility of the signal changes was much better for GE-EPI than for TSE imaging. To conclude, multi-subjects averaged GE-EPI is more location specific for blood-oxygen-level-dependent (BOLD) activation, more sensitive, and is suggested to be more reproducible than TSE fMRI.

Value and limitations of contrast-enhanced MR angiography in spinal arteriovenous malformations and dural arteriovenous fistulas.

BACKGROUND AND PURPOSE: The purpose of this work was to study the validity of MR angiography (MRA) for identification of spinal arteriovenous (AV) abnormalities. MATERIALS AND METHODS: Thirty-four consecutive patients with suspicion of spinal vascular abnormalities underwent digital subtraction angiography (DSA) after MRA. The level and side of the suspected spinal dural arteriovenous fistula (SDAVF) and the feeding arteries in spinal arteriovenous malformations (SAVMs) were determined from the MRA and compared with DSA. RESULTS: DSA revealed SDAVF in 20 abnormalities of which 19 were spinal and 1 was tentorial with spinal drainage, as well as SAVM in 11 patients. In 3 patients, MRA and DSA were both normal. For detection of spinal arteriovenous abnormalities, neither false-positive nor false-negative MRA results were obtained. The MRA-derived level of the feeding artery in SDAVF agreed with DSA in 14 of 19 cases. In 5 cases, a mismatch of 1 vertebral level (not side) was noted for the feeding artery. For the tentorial AVF, only the spinal drainage was depicted; the feeding artery was outside the MRA field of view. In intradural SAVM, the main feeding artery was identified by MRA in 10 of 11 patients. MRA could differentiate between glomerular and fistulous SAVM in 4 of 6 cases and between sacral SDAVF and filum terminale SAVM in 2 of 5 cases. CONCLUSIONS: MRA reliably detects or excludes various types of spinal AV abnormalities and localizes the (predominant) arterial feeder of most spinal AV shunts. Although classification of the subtype of SAVMs remains difficult, with MRA it greatly helps to focus subsequent DSA.

Intracranial multiple midline germinomas: is histological verification crucial for therapy?

In this report we present two patients with intracranial multiple midline tumours in the suprasellar region and pineal gland. We postulate that in a patient with multiple midline tumours and normal values of the tumour markers human chorionic gonadotropin and alpha-fetoprotein in serum and cerebrospinal fluid, the only possible diagnosis is a germinoma. In such a situation no histological confirmation is required to start low-dose radiotherapy.

MR angiography of the great anterior radiculomedullary artery (Adamkiewicz artery) validated by digital subtraction angiography.

BACKGROUND AND PURPOSE: Imaging of the anterior superficial spinal cord arteries by MR angiography is hindered by their small calibers and the similarity in configuration with the anterior superficial spinal cord veins. To validate the location and spatial configuration of the great anterior radiculomedullary artery, (ie, the Adamkiewicz artery [AKA]), contrast-enhanced MR angiography (CE-MRA) was compared with digital subtraction angiography (DSA). METHODS: Fifteen patients with suspected spinal cord vascular pathology underwent both spinal CE-MRA and selective spinal DSA. Two phase CE-MRA was performed with the use of a centric k-space filling scheme synchronized to the contrast bolus arrival. The level and side of the AKA origin were scored on the DSA and CE-MRA images and compared regarding image quality in terms of vessel conspicuity, contrast, continuity, sharpness, and background homogeneity on a relative 5-point scale. RESULTS: Localization and spatial configuration of the AKA by CE-MRA was in agreement with DSA findings in 14 of 15 cases. One mismatch of 1 vertebral level (not side) appeared as a result of the tangled vascular pathology. Comparison of image quality revealed that DSA is superior to CE-MRA concerning vessel continuity, sharpness, and background homogeneity (P < .001). Overall vessel conspicuity and contrast were judged to be similar. CONCLUSION: CE-MRA can visualize and localize the level of the AKA correctly. Image quality of CE-MRA is sufficient for detection of the AKA but is inferior to DSA.

Language activation distributions revealed by fMRI in post-operative epilepsy patients: differences between left- and right-sided resections.

OBJECTIVE: To reveal differences of cerebral activation related to language functions in post-operative temporal lobe epilepsy (TLE) patients. METHODS: Right (RTL) and left temporal lobe (LTL) resected patients, and healthy controls were studied using functional magnetic resonance imaging (fMRI). Only patients with complete left-hemispheric language dominance according to the intracarotid amytal procedure (IAP) were included. Language-related activations were evoked by performing word generation and text reading language tasks. Activation lateralization and temporo-frontal distribution effects were analysed. RESULTS: For word generation, only LTL patients showed reduced left lateralized activation compared to controls, due to a decrease in activation in the left prefrontal cortex and an increase in the right prefrontal cortex. For reading, the left-hemispheric lateralization in RTL patients increased because of enhanced activity in the left prefrontal cortex, whereas for LTL patients the activation became bilaterally distributed over the temporal lobes. Lateralization results between pre-operative IAP and post-operative fMRI were highly discordant. Significant temporo-frontal distribution changes manifested from the reading but not from the word generation task. CONCLUSION: The cerebral language representation in post-operative LTL epilepsy patients is more bi-hemispherically lateralized than in controls and RTL patients. Post-operative temporo-frontal and interhemispheric redistribution effects, involving contralateral homologous brain areas, are suggested to contribute to the cerebral reorganisation of language function.

Sequelae in long-term survivors of small cell lung cancer.

PURPOSE: Central nervous system (CNS) effects of chemotherapy and prophylactic cranial irradiation (PCI) are studied in long-term small cell lung cancer (SCLC) survivors. The exact significance and pathogenesis of the neurotoxicity is still unknown, as studies on this subject lack sufficient patient numbers and are performed in an extremely varied manner. METHODS AND MATERIALS: Fifty-nine survivors (> 2 years from diagnosis) were examined neurologically and neuropsychologically, and underwent a cranial computer tomography (CT) scan or magnetic resonance (MR). Eight patients were excluded from further analysis for various reasons (not SCLC-related CNS disease, n = 6; no chemotherapy nor PCI treatment, n = 2). The remaining 51 patients were divided into three groups; group 1 = chemotherapy alone (n = 21), group 2 = sequential PCI (n = 19), and group 3 = concurrent or sandwiched PCI (n = 11). Groups were neuropsychologically compared in matched controls. RESULTS: Performance status did not differ significantly between various treatment groups; all patients remained ambulatory and capable of self-care. Mental impairment (n = 20), motor abnormalities (n = 9), and visual complaints (n = 1), were found in five patients in group 1 (24%), eight patients in group 2 (42%), and eight patients in group 3 (73%). Analysis of brain atrophy revealed no significant results; however, white matter abnormalities were found more frequently in group 3. Neuropsychologically no significant group differences existed, although interference sensitivity and difficulties with divided attention tended to occur more frequently in patients treated with PCI. Mean neuropsychometric results of treatment groups were significantly worse than those of matched controls. CONCLUSIONS: Although more intensively treated patients showed more neurologic impairment and patients in group 3 had more white matter abnormalities, there was no statistic evidence for additional neurotoxicity of PCI. Marked neuropsychometric differences between patients and matched controls may indicate that cognitive impairment is partly disease related, probably due to emotional distress and deteriorated physical condition.

CT morphology of intrathecal lumbosacral nerve-root compression.

Spinal CT scans and radiculograms of 100 patients who had undergone both examinations were studied with the aim of identifying morphologic CT features associated with compression of the intrathecal segment of the nerve root as demonstrated by radiculography. The interest for such a study lies in the fact that, in contradistinction to the distal, extrathecal root segment outlined by fat in the foramen, the proximal segment within the dural sac cannot be distinguished from the surrounding CSF by CT. CT features assessed consisted of deformation of the dural sac and displacement of the surrounding epidural fat. These features were compared with radiculographic signs of root involvement in the same location: kinking of the nerve root, local swelling of the root within the dural sac or the root sheath, and cutoff of root-sheath filling. In addition, a separate "expert opinion" verdict was given in each location as to the likelihood of compression of the intrathecal root segment on the basis of CT findings as confirmed or rejected by radiculography. A degree of correlation existed between CT and radiculographic features in clearly normal or abnormal locations, but there were some marked discrepancies. In borderline cases there were many discrepancies. The lack of agreement was confirmed by generally disappointing kappa values. The expert opinion, combining separate radiologic features into verdicts for CT and radiculography, did not lead to significantly better agreement as expressed by kappa, but less extreme discrepancies were seen. It proved to be possible, however, to distinguish locations with CT features likely to correlate well the radiculographic picture from those less likely to show good correlation. Such a distinction can guide the decision whether or not to perform confirmatory radiculography. False-positive locations were identified by questionnaire; CT and radiculographic features proved to differ only a matter of degree from the same features is presumably symptomatic locations. CT and radiculographic findings in compression of the intrathecal segment of the nerve root are complementary. Correlating the two studies is of limited value because they provide different anatomic information.

Effects of i.v. contrast administration on intraspinal and paraspinal tissues: a CT study. 1. Measurement of CT attenuation numbers.

Contrast-enhanced CT can be useful in differentiating between recurrent disk herniation and scar formation after disk surgery. Thirty such CT studies were assessed retrospectively to determine the utility of CT attenuation measurements in identifying intraspinal pathology. Measured values of intraspinal tissues, but also of "reference" materials such as CSF, blood, and muscle tissue, showed large individual variations; and enhancement patterns for recurrent herniation and scar formation were not specific. The chief value of contrast administration may lie in the clearer definition that is gained of various structures within the postoperative spine.

Influence of spinal posture on abnormalities demonstrated by lumbar myelography.

During spinal movements the dural end sac undergoes displacement and deformation, chiefly because of bulging of intervertebral disks and flaval ligaments in lumbar extension. Under normal circumstances these dural changes of form do not lead to clinical symptoms. However, in patients with spinal stenosis radiologic signs may be accentuated in lumbar extension. These tend to disappear in flexion. This implies that examination techniques performed in extension (prone lumbar myelography) tend to enhance abnormalities, while techniques in which the spine is more or less flexed (epidural phlebography, computed tomography) tend to mask them. In addition, there may be discrepancy between the picture during surgery (usually in lumbar flexion) and the situation in which a patient experiences symptoms (usually in lumbar extension in spinal stenosis).

Effects of i.v. contrast administration on intraspinal and paraspinal tissues: a CT study. 2. Visual assessment.

Paired and matched CT scans, one before and one after IV injection of contrast material, from 30 spinal CT studies were presented in a blind fashion to six observers with varying degrees of radiologic experience. The observers were asked to indicate which section of each pair gave the best delineation of intraspinal soft tissues. Seventy-five percent of the verdicts indicated the postcontrast image was superior in this respect, but the six observers were unanimous on this in only 50% of the cases. At a follow-up viewing of the same cases several weeks later, some 20% of the verdicts were changed. Experience in interpreting spinal CT scans did not prove to influence rating performance or improve intraobserver consistency. In summary, contrast material, in the dosage and injection mode used by us, appeared to be the most important factor in improving scan interpretation.

Functional MR imaging of the cervical spinal cord by use of median nerve stimulation and fist clenching.

BACKGROUND AND PURPOSE: Findings of blood oxygen level-dependent (BOLD) functional MR (fMR) imaging of the cervical spinal cord, obtained by using a fist-clenching motor task, have been sporadically reported. Because spinal activation by sensory stimuli has a potential at least equal to that of fist clenching, its feasibility was assessed. Whether stimulation of the median nerve could evoke an fMR imaging response at 1.5 T in the cervical spinal cord was investigated, and the response pattern was compared with that obtained by fist clenching. METHODS: A dynamic cardiac-gated T2*-weighted imaging sequence was used to quantify cervical spinal cord activation under two paradigms with different numbers of subjects. Seven subjects underwent electrical median nerve stimulation at the elbow sufficient to elicit a maximal compound muscle action potential in the flexor carpi radialis muscle. Eleven subjects performed self-paced fist clenching. Cord activation was measured in the sagittal and transverse imaging planes. RESULTS: In the sagittal view, five of seven subjects had an fMR imaging response in the lower cervical spinal cord upon median nerve stimulation, whereas seven of 11 subjects showed activation with the fist-clenching task. Within the cord, the measured fMR imaging response level was approximately 8-15% with respect to the baseline signal level. In the transverse imaging plane, significant fMR imaging responses could be measured in only two of six and six of nine subjects with median nerve stimulation or fist clenching, respectively. A consistent cross-sectional localization of the activity measured in the spinal cord was not detected, either in terms of the right and left sides or in terms of the posterior and anterior directions. CONCLUSION: In the sagittal plane, median nerve stimulation at the elbow can evoke an fMR imaging response in the lower cervical spinal cord. The activation pattern was comparable with that obtained by fist clenching. The localization of the segmental fMR imaging activation (C4 through T1) is consistent with the known functional neuroanatomy for both paradigms. In the transverse plane, reliable fMR imaging responses were obtained much less frequently, and assignment of distinct areas of the spinal cord to the stimulation methods used was not possible.

MR imaging, single-photon emission CT, and neurocognitive performance after mild traumatic brain injury.

BACKGROUND AND PURPOSE: Mild traumatic brain injury (mTBI) (Glasgow Coma Scale = 14-15) is a common neurologic disorder and a common cause of neurocognitive deficits in the young population. Most patients recover fully from mTBI, but 15% to 29% of patients have persistent neurocognitive problems. Although a partially organic origin is considered likely, little brain imaging evidence exists for this assumption. The aims of the present study were to establish the prevalence of posttraumatic lesions in mTBI patients on MR images and to assess the relation between these imaging findings and posttraumatic symptoms. Secondly, we explored the value of early posttraumatic single-photon emission CT (SPECT) for the evaluation of mTBI. METHODS: Twenty-one consecutive patients were included in the study. Patients underwent MR examination, technetium-99m hexamethylpropylene amine oxime SPECT, and neurocognitive assessment within 5 days after injury. Neurocognitive follow-up was conducted 2 and 6 months after injury, and MR imaging was repeated after 6 months. Lesion size and brain atrophy were measured on the MR studies. RESULTS: Twelve (57%) of 21 patients had abnormal MR findings, and 11 (61%) of 18 had abnormal SPECT findings. Patients with abnormal MR or SPECT findings had brain atrophy at follow-up. The mean neurocognitive performance of all subjects was within normal range. There was no difference in neurocognitive performance between patients with normal and abnormal MR findings. Patients with abnormal MR findings only showed significantly slower reaction times during a reaction-time task. Seven patients had persistent neurocognitive complaints and one patient met the criteria for a postconcussional syndrome. CONCLUSION: Brain lesions are common after mTBI; up to 77% of patients may have abnormal findings either on MR images or SPECT scans, and these lesions may lead to brain atrophy. The association between hypoperfusion seen on acute SPECT and brain atrophy after 6 months suggests the possibility of (secondary) ischemic brain damage. There is only a weak correlation between neuroimaging findings and neurocognitive outcome.

Peritumoral brain edema associated with meningiomas.

Although generally benign, meningiomas may be associated with extensive peritumoral brain edema, as visualized on computed tomographic (CT) scans. An analysis of 38 meningiomas indicated that severity of edema on CT scans positively correlated with tumor size and also with evidence of disruption of the cortical layer, which initially separates the tumor from the white matter, in which edema tends to accumulate. The various histological subtypes also seemed to be distinct in their tendency to induce edema, with the transitional and meningotheliomatous subtypes associated with the more severe grades of edema. There was no correlation between grade of edema and location of the tumor. Contact of the edematous area or the tumor itself with the ventricle, which is relevant to the possibility of drainage of edema fluid into the ventricle, seemed to occur in cases of the more severe grades of edema rather than in cases showing slight or no edema.

Pathoanatomy of clinical findings in patients with sciatica: a magnetic resonance imaging study.

OBJECT: Anatomical details of nerve root compression may explain the production of the signs and symptoms of sciatica. The authors of anatomical studies have offered many theories without clearly demonstrating the clinical relevance of the observations. Clinicoanatomical series are scarce and are affected to a great extent by selection bias. METHODS: The authors created a schematic drawing of the lumbar anatomy based on both the literature and in vitro anatomical observations. A diagnosis was then made with the aid of detailed and standardized clinical and magnetic resonance (MR) imaging studies in primary-care patients who presented with pain that radiated into the leg. Clinical and MR imaging findings were correlated. Finally, the anatomical drawing was compared with the clinical data. The higher the vertebral level of symptomatic disc herniations, the more likely the compression will be more laterally situated. Classic symptoms of sciatica (typically, dermatomal pain; increase in pain when coughing, sneezing, or straining; and testing positive for pain during straight leg raising) were most likely to occur with compression of the nerve root in the axilla and with mediolateral disc herniations. CONCLUSIONS: The L-3, L-4, L-5, and S-1 nerve roots each tend to be compressed at different sites along the rostrocaudal course of the nerve root. Disc herniations become symptomatic at different sites for each disc level. The schematic drawing produced a priori could well be used to explain these findings. Expectations of particular clinical findings can be predicted by specific pathoanatomical findings.

Rotation of the cervical spine. A CT study in normal subjects.

A computed tomography (CT) study of rotation of the cervical spine was undertaken in normal subjects aged 20 to 26 years. Section scans through the neck were made with the head in maximal rotation to the right or the left. Occiput, cervical spine, and first thoracic vertebra, thus, were depicted in different degrees of rotation with respect to the sagittal plane. These differences indicated the maximal degree of rotation in each of the eight segments between occiput and thoracic spine. Mean values for these segments were 1.0 degree, 40.5 degrees, 3.0 degrees, 6.5 degrees, 6.8 degrees, 6.9 degrees, 5.4 degrees and 2.1 degrees, respectively. Measurement error proved to be relatively small. By means of CT sections in the plane of the intervertebral joints (in three subjects in midposition, in one subject in maximal rotation of the head to one side) an axis of rotation could be constructed from the anatomic shape of the uncovertebral joints. The theory of Hall that the unciform processes are essential for rotation is confirmed and further elaborated.

Posture-dependent bilateral compression of L4 or L5 nerve roots in facet hypertrophy. A dynamic CT-myelographic study.

In 12 patients with myelographic evidence of bilateral root involvement at the L3-L4 or L4-L5 levels postmyelographic computerized tomography (CT) studies were performed in flexion and extension. They showed concentric narrowing of the spinal canal in extension and widening with relief of nerve root involvement in flexion. This could be attributed to the presence of marked degenerative hypertrophy of the facet joints, narrowing the available space for dural sac and emerging root sleeves. In extension of the lumbar spine, bulging of the disc toward the hypertrophic facets causes a pincers mechanism at the anterolateral angles of the spinal canal with the risk of bilateral root compression. This mechanism is enhanced in these cases by marked dorsal indentation of the dural sac because of anterior movement of the dorsal fat pad in extension. The authors believe that the radiologically described mechanism forms the anatomic basis of neurogenic claudication and posture-dependent sciatica.

Biomechanics of lumbosacral dural sac. A study of flexion-extension myelography.

Measurements were performed on 40 lateral lumbar myelograms in flexion and extension with the object of analyzing changes in position and shape of the dural sac in spinal movements. There proved to be an anterior displacement of the entire lumbar dural sac in lumbar extension, most likely caused by shortening and thickening of the flaval ligaments. In addition, the anterior dural surface was indented at the L3-4 and L4-5 interspaces by posterior bulging of the discs in extension. This encroachment was partially compensated by dural bulging into areas with a rich and compressible venous plexus: behind the vertebral bodies and the L5-S1 disc. While the patterns of dural movements showed individual variations, these trends were found in all diagnostic and anatomic subgroups. One subgroup (with root involvement at L4-5) showed marked dorsal encroachment upon the dural sac in extension at the same level. The clinical implications of these findings are discussed.

Atlanto-odontoid osteoarthritis. Appearance and prevalence at computed tomography.

STUDY DESIGN: In this prospective study, the authors evaluated the atlanto-odontoid (AO) joint in 500 consecutive patients who underwent computed tomographies (CTs) of the brain or paranasal sinuses. OBJECTIVES: The objective of the study was to determine age specificity of various morphologic abnormalities related to osteoarthritis at the AO joint in patients referred for CT primarily to exclude brain or sinus abnormalities. SUMMARY OF BACKGROUND DATA: In all patients, at least two axial slices through the AO joint were evaluated by two authors, and agreement was reached by consensus. METHODS: Abnormal morphology was categorized into three groups: (1) osteophytosis; (2) obliteration of the joint space; and (3) transverse ligament calcification. RESULTS: In a significant percentage of older individuals, some form of degenerative disease is present. These changes show a roughly linear progression with advancing age. CONCLUSION: Morphologic changes related to AO osteoarthritis are frequent coincidental findings in patients referred for CT examination of the brain or paranasal sinuses. Awareness of the appearance and prevalence of degenerative changes in the AO joint on CT is important because reports in the literature and earlier findings of the authors indicate that these changes can be a source of suboccipital headache.

Reliability of lumbar spine radiograph reading by chiropractors.

STUDY DESIGN: An intraobserver and interobserver study on the reproducibility of data was performed. OBJECTIVES: This study investigates the variability in the interpretation of lumbar spine radiographs by chiropractors working in private practice. SUMMARY OF BACKGROUND DATA: In chiropractic practice radiographs are used often, but this use is currently under debate. Therefore, there is a need for further study of the value of diagnoses made by radiographs by chiropractors. An acceptable intra- and interobserver agreement in radiograph reading is a prerequisite for a useful application of radiographs as a diagnostic tool in daily practice and in research. METHODS: Four chiropractors read 100 blinded sets of standard, erect anteroposterior and lateral lumbar radiographs independently. The same set was read in two separate sessions with a 2-month interval. The first session revealed the interobserver agreement. The comparison of the ratings by the same assessor in the two sessions indicated the intraobserver agreement. The assessors used a specially developed criteria list with emphasis on "nonspecific" radiographic findings. The prevalence of some important categories was increased artificially. Agreement was expressed in percentage agreement and generalized kappa, combining the results of all four assessors. RESULTS: Most kappas ranged from 0.40 to 0.75, representing fair to good agreement. In general, intraobserver agreement was better than interobserver agreement. The low kappas that were found may be explained partially by the high-agreement-low-kappa paradox as a result of a low prevalence. CONCLUSION: The kappas and percentage agreement were acceptable, although not excellent. These results will be beneficial for future research on the value of radiograph diagnosis of nonspecific findings for delivery of safe and effective chiropractic therapy.

Complementary values of static and dynamic scintigraphy, computerized tomography and angiography in the diagnosis of a partially thrombosed giant intracranial aneurysm.

The case history is presented of a 17 year-old male admitted with right hemiplegia and motor aphasia. Static and dynamic scintigraphy allowed prediction of a giant aneurysm in the deep left frontotemporal region, and this supposition was confirmed by CT and carotid angiography. CT also revealed the aneurysm to extend farther medially than the other two examinations had indicated, the medial portion of the aneurysm being thrombosed. Evaluation of the diagnostic information obtained from the three procedures, combined with the clinical data, makes possible a reconstruction of the probable course of events. The presenting signs were probably caused by a newly formed thrombus within the aneurysm. Death, which occurred after five days, was apparently due to subarachnoid hemorrhage.