Biomedical subjects

V M Haughton

Publications and source records attributed to V M Haughton.

At least 19 recordsLinked to original sources

PubMed1995

Atypical demyelinating lesions in patients with multiple sclerosis.

We describe an atypical MRI appearance of multiple sclerosis (MS). Lesions characterized on T2-weighted images by a well-defined rim of increased signal intensity and a concentric region of higher signal intensity were seen in 6 of 132 patients with MS. On T1-weighted images these lesions were evident as regions of low signal intensity, often with a rim of contrast enhancement or increased signal intensity. These appearances tended to be shown by new, evolving lesions.

Adult↗

PubMed1995

Functional magnetic resonance imaging mapping of the sensorimotor cortex with tactile stimulation.

The purpose of this study is to compare tactile stimulation of the palm with voluntary movement of the fingers as paradigms for mapping the sensorimotor cortex in functional magnetic resonance imaging. In 22 subjects, 24 sets of functional magnetic resonance images were obtained with echoplanar acquisitions and cross-correlation image processing techniques. Two tasks were employed: a motor task in which subjects moved the thumb and index finger of one hand and a sensory task in which the palm was scratched by another person. The activation from the two tasks coincided entirely in 20 sets and partially in 3 sets. In one case, no activation was seen with the motor task. The study suggests that tactile stimulation of the palm is useful and reliable for mapping the sensorimotor cortex.

Adult↗

PubMed1995

Anatomy of cervical spine.

A knowledge of the cervical spine anatomy provides the basis for understanding and interpreting magnetic resonance imaging studies. Because magnetic resonance imaging provides multiplanar images, this article describes anatomic relationships in multiple planes. The anatomic relationships of the spinal nerves and the neural foramina and spinal cord in the central canal are emphasized, and the location of fluid and fat, which have distinctive appearances in magnetic resonance imaging, is noted.

Cervical Vertebrae↗

PubMed1995

A comparison of functional MR activation patterns during silent and audible language tasks.

PURPOSE: To compare word generation tasks performed silently and aloud as paradigms for functional MR. METHODS: Images were obtained at 1.5 T, with echoplanar acquisition in nine subjects performing word generation aloud or silently. Functional images created from the echoplanar images by means of cross-correlation techniques were superimposed on anatomic reference images. The location of activation from the two tasks was tabulated; the number of activated pixels in each region from the two tasks was compared. RESULTS: Both silent and aloud word generation produced activation in the inferior frontal lobes, sensorimotor cortex regions, supplementary motor areas, and anterior cingulate gyri, predominantly in the dominant hemisphere. Significantly more activated pixels and fewer artifacts were detected with silent word generation than with word generation aloud. CONCLUSION: Word generation silently or aloud produce activation in the brain. Greater activation can be detected in the left frontal lobe with silent word generation, although the subject's performance of the task cannot be monitored independently during silent word generation.

Adult↗

PubMed1995

Contrast enhancement in spinal nerve roots: an experimental study.

PURPOSE: To examine histopathologically the endothelium of contrast-enhancing spinal nerve roots. METHODS: In five adult baboons, chronic compression of the left S-1 spinal nerve root sufficient to produce a change in the evoked potential was produced by means of a suture tied around the nerve. The animals were studied with MR at 8 and 16 days after nerve compression and then killed for histopathologic and electron microscopic studies. Histopathologic changes in the nerve roots demonstrating contrast enhancement were described. RESULTS: In all compressed spinal nerves, contrast enhancement was observed. Histopathologically, wallerian degeneration of the root and inflammation and disruption of the endothelium of capillaries in the spinal nerve were evident. CONCLUSIONS: Degenerative changes in the nerve root and the capillary endothelium of a lumbar spinal nerve are associated with contrast enhancement.

Animals↗

PubMed1995

Lumbar foraminal stenosis: critical heights of the intervertebral discs and foramina. A cryomicrotome study in cadavera.

One hundred lumbar intervertebral foramina from eighteen spines of fresh cadavera were studied to assess the relationship between compression of the nerve root and the height of the intervertebral disc and the morphological characteristics of the intervertebral foramen as determined on cryomicrotome sections. The critical posterior disc height and the critical foraminal height that were associated with entrapment and compression of the nerve root were determined. Significant positive correlations were demonstrated between compression of the nerve root and the posterior disc height, the foraminal height, and the foraminal cross-sectional area for the four intervertebral levels between the second lumbar and first sacral vertebrae. Nerve-root compression was evident in twenty-one of the 100 foramina, in eight of the ten foramina in which the posterior disc height was four millimeters or less, and in four of the five foramina in which the foraminal height was fifteen millimeters or less. These critical dimensions may be indicators of foraminal stenosis in the lumbar spine. However, compression of a spinal nerve root does not always cause sciatica, and the clinical findings must always be taken into account when a diagnosis of stenosis is considered.

Adult↗

PubMed1994

Gadolinium-enhancement characteristics of magnetic resonance imaging in distinguishing herniated intervertebral disc versus scar in dogs.

STUDY DESIGN: This study is an experimental investigation on the gadolinium contrast magnetic resonance imaging (MRI) in distinguishing sequestered disc fragment versus scar in dogs. The conspicousness of the disc fragment and signal intensities of the disc fragment and laminectomy scar were evaluated using gadolinium-enhanced MRI and histology. OBJECTIVES: This study investigated the effects of timing of gadolinium injections, gadolinium doses, and aging of scar or disc on the enhancement characteristics and conspicuousness of disc fragment in MRI. SUMMARY OF BACKGROUND DATA: Contrast-enhanced MRI has been frequently used as a procedure to evaluate patients with suspected recurrent herniated discs. In contrast-enhanced MRI, the postoperative scar tissue enhances to a greater extent than disc fragments. Previous reports suggest different contrast enhancement characteristics of scar depending on doses, timing of gadolinium, or maturity of scar. There are different compounds of gadolinium agents and different doses are becoming available. There is no previous report on the evaluation of gadolinium enhancement characteristics in dogs with concurrent herniated disc and scar. METHODS: Six conditioned Beagle dogs underwent hemilaminectomies and discectomies at the L3-L4 level. An autogenous disc fragment was obtained from the intervertebral disc of the tail. This disc fragment was placed anterolateral to the thecal sac, simulating a sequestered disc herniation. Three control animals underwent hemilaminectomies and discectomies alone. Each dog underwent MRI on a 1.5 Tesla scanner (3.0 mm slice in sagittal and axial projections with TR 500, TE 30 msec and high dose 0.3 mmol/kg of gadoteridol). Images were obtained at 15 days, 30 days, 60 days, and 90 days after surgery. At each imaging session, contrast enhancement was measured at 2 minutes, 25 minutes, and 45 minutes after gadolinium injection for kinematic analysis. Two animals at a time were killed on 30 days, 60 days, and 90 days postoperatively. Magnetic resonance imaging was done with conventional low dose 0.1 mmol/kg of gadopentetate at 15 days and before death. RESULTS: Results revealed that the difference of enhancement between disc and the scar and therefore conspicuousness of disc fragment was greater on 2-23-minute images as compared with 45- minute images, and the distinction decreased with aging of the scar. The high dose contrast-enhanced MRI increased signal intensities for both disc and scar. Conspicuousness of disc fragment seemed to be better with the high-dose gadolinium compound. CONCLUSIONS: In conclusion, contrast enhancement characteristics in MRI may depend on the timing of MRI after gadolinium injection, doses of gadolinium, and aging of scar or disc.

Animals↗

PubMed1994

Functional magnetic resonance imaging of human auditory cortex.

Magnetic resonance imaging methods recently demonstrated regional cerebral signal changes in response to limb movement and visual stimulation, attributed to blood flow enhancement. We studied 5 normal subjects scanned while listening to auditory stimuli including nonspeech noise, meaningless speech sounds, single words, and narrative text. Imaged regions included the lateral aspects of both hemispheres. Signal changes in the superior temporal gyrus and superior temporal sulcus were observed bilaterally in all subjects. Speech stimuli were associated with significantly more widespread signal changes than was the noise stimulus, while no consistent differences were observed between responses to different speech stimuli. Considerable intersubject variability in the topography of signal changes was observed. These observations confirm the utility of magnetic resonance imaging in the study of human brain structure-function relationships and emphasize the role of the superior temporal gyrus in perception of acoustic-phonetic features of speech, rather than processing of semantic features.

Acoustic Stimulation↗

PubMed1994

Safety and efficacy of iopromide in cerebral arteriography.

RATIONALE AND OBJECTIVES: Iopromide is a new nonionic monomeric contrast medium for cerebral arteriography. This agent has been approved for sale in over 45 countries; however, it is still undergoing clinical review in the United States. This study evaluated the safety and efficacy of iopromide in comparison with two other nonionic contrast media. METHODS: A total of 173 patients participated in the study, which was prospective, double-blind, and randomized. In two centers, patients received iopromide or iohexol; in the other three centers, patients received iopromide or iopamidol. Adverse events were monitored by investigators, and efficacy was evaluated by grading the radiographic images. RESULTS: Most adverse events were mild or moderate in severity; all resolved completely. Twenty-one percent of patients given iopromide were reported to have a drug-related adverse event, versus 44% of patients given a comparator. No statistically significant difference emerged between iopromide and the comparators with regard to efficacy. CONCLUSIONS: These study results indicate that iopromide is a safe and effective contrast medium for cerebral angiography.

Cerebral Angiography↗

PubMed1994

Functional magnetic resonance imaging of somatosensory stimulation.

Functional magnetic resonance imaging (FMRI) has detected changes in regional cerebral blood flow and volume in response to motor movements, visual stimuli, and auditory stimuli in each of their respective primary cortices. This experiment was conducted to determine whether signal changes in the somatosensory cortex secondary to tactile stimulation could be demonstrated. The palm of the right hand was periodically stimulated while the subject was undergoing echo-planar imaging with a 1.5-T magnetic resonance scanner equipped with local gradient and radio frequency coils. Sagittal and coronal images of 10- to 15-mm slice thickness were selected to include the postcentral gyrus and surrounding regions. Temporally correlated signal changes of 1% to 5% occurred in the peri-rolandic region in each of six subjects. The time course of signal changes was comparable to that found in other primary sensory and motor cortices. The results provide preliminary evidence of the sensitivity of FMRI to activation of the somatosensory cortex with tactile stimulation and support FMRI as a promising noninvasive technique for study of the functional organization and integrity of the cerebrum.

Adult↗

PubMed1994

Effect of dose and field strength on enhancement with paramagnetic contrast media.

PURPOSE: To compare contrast enhancement per unit of dose of contrast medium in MR imaging at 0.5 and 1.5 T. METHODS: Contrast enhancement in images made at 0.5 and 1.5 T after 0.1 mmol/kg of gadopentetate dimeglumine and 0.3 mmol/kg of gadodiamide was measured and the degree of contrast enhancement in the cavernous sinus and pituitary gland compared. RESULTS: At both field strengths and both contrast medium doses, contrast enhancement was noted in the cavernous sinus, pituitary gland, infundibulum, maxillary sinus mucosa, falx cerebri, and choroid plexus on inspection of images. Enhancement was significantly and conspicuously less in the cavernous sinus and pituitary gland at 0.5 T (96% and 33%, respectively) than at 1.5 T (160% and 102%, respectively). No tissues were identified that enhanced only with the larger dose or higher field strength. CONCLUSION: In tissues that normally enhance after intravenous administration of gadolinium chelates, enhancement is greater at 1.5 T than at 0.5 T.

Brain Neoplasms↗

PubMed1994

Enhancement of intervertebral disks with gadolinium complexes: comparison of an ionic and a nonionic medium in an animal model.

PURPOSE: To compare MR contrast enhancement of intervertebral disk tissue after intravenous administration of equimolar doses of an ionic and of a nonionic gadolinium complex. METHODS: Contrast enhancement was measured on MR in lumbar intervertebral disks for 120 minutes after intravenous injection of gadoteridol or gadopentetate dimeglumine, 0.3 mmol/kg. MR studies were performed with each contrast medium in four rabbits. Contrast enhancement was measured in intervertebral disks as a function of time and contrast medium. RESULTS: With both contrast media, enhancement of normal intervertebral disks was detected. Enhancement of disks was significantly greater with gadoteridol than with gadopentetate dimeglumine. CONCLUSION: The enhancement of cartilage is influenced by the molecular structure of the gadolinium complex. The negative charge of gadopentetate dimeglumine may give it a slower rate of diffusion into disk cartilage than a nonionic complex.

Animals↗

PubMed1994

Utility of high-dose contrast enhancement for detecting recurrent herniated intervertebral disks.

PURPOSE: To study the utility of high-dose contrast enhancement in the detection of recurrent herniated disk fragments. METHODS: Recurrent herniated disks were modeled in nine dogs by placing a fragment of normal autologous disk tissue in the epidural space at laminectomy. MR was performed at 30, 60, and 90 days with 0.3 mmol/kg of gadoteridol and repeated 24 hours later with 0.1 mmol/kg of gadopentetate dimeglumine. Contrast enhancement in the disk and scar tissue was measured and conspicuousness of the disk fragments assessed. RESULTS: In 70% of the animals, disk fragments were more conspicuous with the larger dose of contrast medium than with the smaller dose. In 30% of animals the conspicuousness was approximately equal. Contrast between disk fragment and scar decreased with time elapsed since surgery, with time elapsed since contrast-medium injection, and with decreasing dose of contrast medium. CONCLUSION: In the experimental model, increased conspicuousness of disk fragments was achieved with the larger dose of contrast medium. A clinical study is needed to confirm that a contrast-medium dose of 0.3 mmol/kg improves detection of recurrent herniated disks over a dose of 0.1 mmol/kg.

Animals↗

PubMed1994

Imaging white matter tracts and nuclei of the hypothalamus: an MR-anatomic comparative study.

PURPOSE: To evaluate the MR appearance of the hypothalamus and its associated white matter tracts. METHODS: Coronal and sagittal spin-echo images were obtained in cadaver brains. Gross and histologic sections were made of the cadaver brains. The size, shape, signal intensity, course, and pattern of structures in the hypothalamic region were identified in MR images by comparison with the anatomic sections. RESULTS: The mamillary bodies, paraventricular zone of hypothalamic nuclei, postcommissural fornix, mammillothalamic fasciculus, and anterior commissure were identified on the MR images. CONCLUSION: This study suggests that, with MR imaging of sufficiently high resolution, some of the tracts and nuclei in the hypothalamus may be identified.

Humans↗

PubMed1994

Contrast enhancement of normal intervertebral disks: time and dose dependence.

PURPOSE: To determine the dose of contrast medium and the imaging strategy sufficient to detect diffusion of low-molecular-weight gadolinium-containing contrast media into normal intervertebral disks. METHODS: In 11 rabbits, sequential MR images were obtained of the spine for 120 minutes after intravenous injection of gadopentetate dimeglumine in doses of 0.1 to 2.8 mmol/kg. Images were inspected for evidence of contrast enhancement. Signal intensity was measured and plotted as a function of time and dose. RESULTS: Contrast enhancement was detected by inspection of images and by measurement in animals receiving doses of 0.3 mmol/kg and larger. CONCLUSIONS: Diffusion of gadolinium-containing chelates into the intervertebral disk can be detected with clinically used doses of commercially available contrast medium. Therefore, with MR and a gadolinium-containing contrast medium, diffusion into intervertebral disks can be studied.

Animals↗

PubMed1993

Ideal thickness of Smith-Robinson graft for anterior cervical fusion. A cadaveric study with computed tomographic correlation.

To establish the optimal thickness for Smith-Robinson anterior cervical fusion grafts, anterior C4-5 discectomy and fusions were performed on six fresh, frozen cadavers. Plain radiographs and computed tomographic scans then were employed to correlate graft placement with changes in disc space height, foraminal height, and foraminal areas after 3-, 5-, 7-, and 9-mm interbody fusions. The ideal graft thickness appeared to be directly related to the preoperative baseline disc height. For a preoperative disc height of 3.5-6.0 mm, an interbody graft of 2 mm above baseline thickness was most appropriate. A thicker graft was required when the baseline disc height was smaller (2.0 mm) and a thinner graft when the disc height was larger (7.4 mm). No significant correlation was noted between disc space distraction at C4-5 and disc height, foraminal height, or foraminal area at adjacent levels.

Aged↗

PubMed1993

Imaging anatomy of the lateral lumbar spinal canal.

This article reviews the normal anatomy of the bony and soft tissue structures of the lateral lumbar spinal canal. Thorough knowledge of these imaging anatomy helps in making the correct diagnosis of the lumbar spinal lesions. CT and MRI are excellent tools to diagnose lateral lumbar spinal canal stenosis. Both CT and MRI provide the accurate measurements of the midsagittal and lateral spinal canals and show the abnormalities of the nerve root course. This review provides anatomic and radiographic descriptions of the lateral lumbar spinal canal and the anatomically related joints.

Humans↗

PubMed1993

Nondiscogenic lumbar radiculopathy: imaging considerations.

This article reviews the differential diagnosis of lumbar radiculopathy, clinical presentations of spinal stenosis, pathological anatomy, and roentgenographic considerations of lumbar spinal stenosis. Most patients suspected of symptomatic spinal stenosis should have plain roentgenograms first to rule out other obvious lesions and to evaluate disc space and foraminal narrowing. Plain roentgenograms also show the sagittal and coronal deformities if present. The next procedure for the evaluation of spinal stenosis after plain roentgenograms should be MRI, as myelogram or CT can be avoided in most cases. In select cases, patients who cannot get MRI or those who underwent MRI with unresolved questions should have a myelogram or CT for further evaluation.

Diagnosis, Differential↗