Evaluation of intervertebral disc herniation and hypermobile intersegmental instability in symptomatic adult patients undergoing recumbent and upright MRI of the cervical or lumbosacral spines.

PURPOSE: The purpose of the study was to determine the difference in findings between recumbent and upright-sitting MRI of the cervical and lumbosacral spine in patients with related sign and symptoms. MATERIALS AND METHODS: A total of 89 patients were studied (lumbosacral spine: 45 patients; cervical: 44 patients). T1-weighted (TR: 350, TE: 20) fast spin echo and T2-weighted (TR: 2500, TE: 160) fast spin echo images were acquired in the sagittal and axial planes in both the recumbent and sitting-neutral positions. The images were acquired on the Upright MRI unit (Fonar Corporation, Melville, NY). Differences were sought between the recumbent and upright-sitting positions at all levels imaged, in both planes. RESULTS: The total number of cases of pathology was 68, including instances of posterior disc herniation and anterior and posterior spondylolisthesis. Focal posterior disc herniations were noted in 55 patients (cervical: 31, lumbosacral: 24) [62% of patients]. Six of these herniations (cervical: 4, lumbosacral: 2) [11%] were seen only on the upright-sitting study. Focal posterior disc herniations were seen to comparatively enlarge in size in 35 patients on the upright-seated examination (cervical: 21, lumbosacral: 14) [72%], and reduce in size in 9 patients (cervical: 5, lumbosacral: 4) [18%]. Degenerative anterior (n: 11) and posterior (n: 2) spondylolisthesis was seen in 13 patients (cervical: 0, lumbosacral: 13) [15% of patient total]. Anterior spondylolisthesis was only seen on the upright-seated examination in 4 patients (cervical: 0, lumbosacral: 4) [31%]. Anterior spondylolisthesis was comparatively greater in degree on the upright-seated study in 7 patients (cervical: 0, lumbosacral: 7) [54%]. Posterior spondylolisthesis was comparatively greater in degree on the recumbent examination in 2 patients (cervical: 0, lumbosacral: 2) [15%]. The overall combined recumbent miss rate in cases of pathology was 15% (10/68). The overall combined recumbent underestimation rate in cases of pathology was 62% (42/68). The overall combined upright-seated underestimation in cases of pathology was 16% (11/69). CONCLUSIONS: Overall, upright-seated MRI was found to be superior to recumbent MRI of the spine in 52 patents (recumbent missed pathology [n: 10]+recumbent underestimated pathology [n: 42]=52/89 total patients: 58%) in cases of posterior disc herniation and anterior spondylolisthesis. This seems to validate the importance of weight-bearing imaging in the spine that might be expected to unmask positional enlarging disc herniations and worsening spondylolisthesis. Overall, recumbent MRI was found to be superior to upright-seated MRI in 11 cases (11/89: 12%). The latter finding was possibly due to the fact that upright seated position is actually partial flexion that might be expected to reduce some cases of hypermobile posterior spondylolisthesis.

The value of fat saturation sequences and contrast medium administration in MRI of degenerative disease of the posterior/perispinal elements of the lumbosacral spine.

Degenerative-inflammatory lumbar spinal pathology is one of the most common reasons why individuals seek medical care, and low back pain is the main symptom among those most commonly associated with this pathologic condition. Pain is commonly attributed to degenerative disc disease, particularly herniated discs, but many different spinal and perispinal structures may undergo degenerative-inflammatory phenomena and produce pain: discs, bone, facet joints, ligaments and muscles. In particular, in patients with non-radicular low back pain, this syndrome may arise from changes of the posterior elements/perispinal tissues of the lumbar spine (i.e., the "posterior vertebral compartment"). They include: facet joint pathology (e.g., osteoarthritis, joint effusion, synovitis and synovial cysts), spondylolysis, spinal/perispinal ligamentous degenerative-inflammatory changes and perispinal muscular changes. It is well known that magnetic resonance is the most sensitive imaging method for the evaluation of spinal degenerative pathology, even in the initial stages of the disease. T2-weighted sequences with fat saturation, and when indicated the use of contrast-enhanced T1-weighted images with fat saturation, permit the visualization of degenerative-inflammatory changes of the posterior elements of the lumbar spine that in most cases would have been overlooked with conventional non-fat suppressed imaging.

MRI cisternography with gadolinium-containing contrast medium: its role, advantages and limitations in the investigation of rhinorrhoea.

Our purpose was to evaluate the utility of intrathecal gadopentetate dimeglumine -enhanced magnetic resonance cisternography (GdMRC). We injected 0.5 ml contrast medium into the subarachnoid space via lumbar puncture in 20 patients with suspected cerebrospinal fluid (CSF) rhinorrhoea. MRC showed CSF leakage in 14 patients with rhinorrhoea at the time of the examination, into the ethmoid air cells in nine, the sphenoid sinus in three and the frontal sinus in two cases. In 12 of these the site leakage was confirmed during surgical repair of the fistula. No leakage was observed in four patients with intermittent rhinorrhoea, not present at the time of the examination. GdMRC showed leakage in two patients with negative CT cisternography. GdMRC may prove better than CT cisternography, especially with slow CSF flow. We also showed low-dose GdMRC to be a feasible and relative safe way of confirming the presence of and localising active CSF leaks prior to surgical repair.

Review article: MRI of the postoperative lumbar spine.

Imaging assessment of the lumbosacral spine following surgery is complex and depends upon several factors, including the anatomy of the patient, the surgical procedure and the disease process for which it was performed, the age of the patient, the biomechanical condition of the underlying cortical and cancellous bone, intervertebral disc and musculoligamentous tissues, the time since surgery procedure and the duration and nature of the postsurgical syndrome. Depending upon these factors, one or a combination of complementary imaging modalities may be required to demonstrate any clinically relevant abnormality, to assist the surgeon in deciding if repeat surgery is necessary, its nature and at which vertebral level(s) it should be directed. This review stresses the important role of MRI following lumbar discectomy, intervertebral fusion and/or instrumentation in achieving the most beneficial and timely outcome in the patient presenting with an acute, subacute or chronic failed back surgery syndrome.

Central nervous system: review of clinical use of contrast media.

The clinical utility of intravenous contrast administration for magnetic resonance imaging in neoplastic disease of the brain, non-neoplastic disease of the brain, and in disease of the spine is reviewed. Magnetic resonance imaging (MRI) is the modality of choice for the evaluation of most suspected intracranial and spinal pathology. Contrast use substantially improves lesion detection and differential diagnosis. Applications are discussed in neoplastic disease, infection, vascular disorders, demyelinating disease, and trauma (specifically including in the spine disk herniation). Gadolinium chelates play as important a role in magnetic resonance imaging as do iodinated agents in computed tomography. Contrast administration facilitates time-efficient and cost-effective diagnosis.

CT and MRI characteristics of ossification of the ligamenta flava in the thoracic spine.

The purpose of this study was to compare MRI findings with CT findings of mass-forming calcification/ossification of the thoracic ligamenta flava (OTLF). Twenty-one Chinese patients presented with clinical evidence of chronic and progressive thoracic spinal cord compression which included: difficulty in walking; weakness; and/or numbness of the extremities, back pain, and lower extremity paresthesias. Axial and sagittal T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) were performed through the thoracic spine on a 1.0-T Impact unit (Siemens, Erlangen, Germany). Axial CT was obtained with 5-mm contiguous sections through the thoracic region. Decompressive surgery with resection of the OTLF were carried out in all patients. Low signal intensity of the mass-forming OTLF was demonstrated at a single level (n=1) or at multiple levels (n=20) on both T1WI and T2WI. The distribution of OTLF was bilateral at all levels identified in 6 cases, unilateral at all levels in 5 patients, and both unilateral and bilateral at different levels in 10 cases. Ossification of the thoracic ligamenta flava involved the upper thoracic spine (T1-4) in 3 cases, midthoracic spine (T5-8) in 3 cases, lower thoracic spine (T9-12) in 10 cases, and more than one thoracic spinal subregion in 5 cases. Computed tomography confirmed the MR findings regarding the location and distribution of OTLF in all cases, as well as the associated evidence of central spinal canal stenosis. In addition, 5 patients revealed associated ossification of the posterior longitudinal ligament. All patients demonstrated gradual, but incomplete, clinical improvement of the radiculomyelopathy following decompressive surgery. Ossification of the posterior longitudinal ligament resulting in thoracic central spinal canal stenosis and clinical radiculomyelopathy is not uncommon in the Asian people. Ossification of the thoracic ligamenta flava can be accurately evaluated equally well by CT and MR with regard to level(s) and side(s) of involvement, as well as to the relative degree of central spinal canal stenosis and the associated compression of the thoracic spinal cord.

Sterile, benign radiculitis associated with lumbosacral lateral recess spinal canal stenosis: evaluation with enhanced magnetic resonance imaging.

Two cases of symptomatic lumbar lateral recess stenosis are described in which the compressed nerve root became focally enhanced on magnetic resonance imaging (MRI) studies performed with gadolinium DTPA. Two men with low back pain and lumbar radiculopathy were examined with contrast-enhanced MRI studies, which showed intradural enhancement of the symptomatic nerve roots. In selected cases of lateral recess stenosis, focal radicular injury may be visualized on enhanced MRI as a result of a breakdown of the blood-brain barrier.

Acute and subacute physiological and histological studies of the central nervous system after intrathecal gadolinium injection in the anesthetized rat.

RATIONALE AND OBJECTIVES: To determine the acute physiological and subacute neurohistological effects of gadopentetate dimeglumine (GdD) administered intrathecally. METHODS: Twenty-four rats were separated into two study groups. In the first group, the acute effects of intrathecal GdD on cortical electroencephalographic activity, renal sympathetic nerve activity, arterial blood pressure, and heart rate were determined. In the second group, histological evaluation of the neural tissues was performed 10 days after treatment. In both the physiological and histological studies, a single GdD dose of 2.5 micromol/g brain (10 microL) was administered intrathecally. Control animals were injected intrathecally with the same volume of a sucrose solution that had the same osmolality as GdD. RESULTS: In the physiological study, GdD and sucrose injections elicited no significant change in any of the parameters recorded. In the histologic study, examination revealed two cases of pre-existing chronic spinal cord gliosis; one of these rats also exhibited signs of pre-existing chronic choroid plexus inflammation. No acute or subacute alterations observed could be specifically linked to the intrathecal administration of GdD. CONCLUSIONS: Intrathecally administered GdD was accompanied by no significant change in any of the physiologic or histologic parameters examined. Based on the relatively short time interval between GdD treatment and histologic examination, the neural tissue abnormalities (gliosis/inflammation) observed in two animals were judged to be incidental and likely due to prior chronic pre-existing processes such as viral infection. Although additional studies are required to verify the safety and effectiveness of intrathecal GdD in humans, data from the present study in animals provide evidence that when intrathecal GdD is used in doses sufficient to improve MRI of the cerebrospinal fluid compartment, it is likely to be accompanied by a low incidence of acute changes in neural function or structure.

The postsurgical lumbosacral spine. Magnetic resonance imaging evaluation following intervertebral disk surgery, surgical decompression, intervertebral bony fusion, and spinal instrumentation.

It should be clear to those who perform and interpret medical images of the spine following one or more forms of surgical therapy that the images are often difficult to interpret in part because of the superimposition of the original disease process, alteration engendered by the surgery, or a complication of the surgical procedure. Although long-term experience in this area is helpful in regard to improving interpretive skills, certain sequela can be predicted regardless of the interpreter's background. Once the normal or expected postsurgical findings are understood, the subtle and gross changes that depart from these observations can be analyzed better. The importance of a high level of competence in the domain of post-therapeutic neurodiagnostic imaging is in the knowledge that the patient returning for restudy may be acutely in distress or even in medical danger (e.g., postoperative spondylitis). In fact, the clinical presentation posttherapeutically may well be more severe or dire than was observed pretherapeutically. An indepth appreciation of the broad range of clinicoradiologic possibilities as presented [figure: see text] here should place the medical imaging physician in an excellent position to provide an experienced diagnostic evaluation in the patient presenting with recurrent or new signs and symptoms following any one of the spectrum of possible spinal surgical procedures.

Acquired degenerative changes of the intervertebral segments at and suprajacent to the lumbosacral junction. A radioanatomic analysis of the nondiskal structures of the spinal column and perispinal soft tissues.

In earlier evolutionary times, mammals were primarily quadrupeds. However, other bipeds have also been represented during the course of the Earth's several billion year history. In many cases, either the bipedal stance yielded a large tail and hypoplastic upper extremities (e.g., Tyrannosaurus rex and the kangaroo), or it culminated in hypoplasia of the tail and further development and specialization of the upper extremities (e.g., nonhuman primates and human beings). In the human species this relatively recently acquired posture resulted in a more or less pronounced lumbosacral kyphosis. In turn, certain compensatory anatomic features have since occurred. These include the normal characteristic posteriorly directed wedge-shape of the L5 vertebral body and the L5-S1 intervertebral disk; the L4 vertebral body and the L4-L5 disk may be similarly visibly affected. These compensatory mechanisms, however, have proved to be functionally inadequate over the long term of the human life span. Upright posture also leads to increased weight bearing in humans that progressively causes excess stresses at and suprajacent to the lumbosacral junction. These combined factors result in accelerated aging and degenerative changes and a predisposition to frank biomechanical failure of the subcomponents of the spinal column in these spinal segments. One other specific problem that occurs at the lumbosacral junction that predisposes toward premature degeneration is the singular relationship that exists between a normally mobile segment of spine (i.e., the lumbar spine) and a normally immobile one (i.e., the sacrum). It is well known that mobile spinal segments adjacent to congenitally or acquired fused segments have a predilection toward accelerated degenerative changes. The only segment of the spine in which this is invariably normally true is at the lumbosacral junction (i.e., the unfused lumbar spine adjoining the fused sacrum). Nevertheless, biomechanical failures of the human spine are not lethal traits; in most cases today, mankind reaches sexual maturity before spinal biomechanical failure precludes sexual reproduction. For this gene-preserving reason, degenerative spinal disorders will likely be a part of modern societies for the foreseeable eternity of the race. The detailed alterations accruing from the interrelated consequences of and phenomena contributing to acquired degenerative changes of the lumbosacral intervertebral segments as detailed in this discussion highlight the extraordinary problems that are associated with degenerative disease in this region of the spine. Further clinicoradiologic research in this area will progressively determine the clinical applications and clinical efficacy of the various traditional and newer methods of therapy in patients presenting with symptomatic acquired collapse of the intervertebral disks at and suprajacent to the lumbosacral junction and the interrelated degenerative alterations of the nondiskal structures of the spine.

Clinics in diagnostic imaging (47). Huntington's disease.

A 38-year-old man presented with progressive worsening of choreiform movements. Serum biochemistry analysis did not reveal any abnormality. Magnetic resonance imaging demonstrated symmetrical caudate nucleus atrophy and generalised cerebral strophy. Huntington's disease was diagnosed in view of the clinical presentation and the characteristic imaging findings. The clinical, pathological and imaging features of this disease process are discussed.

Clinics in diagnostic imaging (51). Multiloculated cerebral abscesses due to paradoxical cardiac emboli.

A 19-year-old woman with congenital cyanotic heart disease (Epstein anomaly and ventricular septal defect) had persistent headaches and intermittent fever for five weeks. Physical examination revealed central cyanosis, finger clubbing and fever. The leucocyte count was elevated. Cerebral MR imaging showed the characteristic features of brain abscesses in the right frontal lobe, including multiloculation with adjacent satellite lesions, ring enhancement, T1-hyperintense and T2-hypointense signal areas within the abscess rim, as well as hypointense internal concentric rings on T2-weighted images. The diagnosis of brain abscesses was confirmed by craniotomy and pus drainage. She made a good recovery with a combination of antibiotics and surgery. Follow-up CT scans showed only changes of encephalomalacia at the healed abscess site. The aetiology, clinical features, and the role of CT and MR imaging in the diagnosis and management of brain abscess are discussed.

MRI of radiation myelitis: a report of a case treated with hyperbaric oxygen.

Radiation therapy is commonly applied as a primary or adjuvant therapy for malignancies. One of the major complications following radiation therapy is the necrosis of the otherwise normal surrounding soft tissues and/or bone. Post-radiation myelopathy rarely occurs when the spinal cord is included within the radiation field, in cases of high total radiation doses or for high radiation doses per fractionation. Up until the present, no tolerance dose for the spinal cord has accurately been defined and no treatment has proved satisfactory. Hyperbaric oxygen therapy is already currently used as adjuvant treatment for osteoradionecrosis and for radionecrosis of soft tissues with satisfactory results, whereas results for the treatment of post-attinic myelitis were contradictory. The aim of our report is to describe a case of radiation myelitis with a progressive improvement in the clinicoradiologic picture following hyperbaric oxygen treatment.

MRI of infections and neoplasms of the spine and spinal cord in 55 patients with AIDS.

Our purpose was to describe the range of MRI findings in infectious and neoplastic involvement of the spine and spinal cord in symptomatic patients with the acquired immunodeficiency syndrome (AIDS). MRI studies in 55 patients with AIDS and neurological signs and symptoms thought to be related to the spine or spinal cord were reviewed. We categorized the findings according to the spinal compartment involved. There were 29 patients with extradural, 11 with intradural-extramedullary and 9 with intramedullary disease. In 6 patients more than one compartment was involved simultaneously, and patients presented with multiple lesions in the same compartment. The most common causes of extradural disease were bone lesions (28); an epidural mass was seen in 14 and spondylodiscitis in 4 patients. Cytomegalovirus polyradiculitis was the most common cause of intradural-extramedullary disease (in 10 cases); herpes radiculitis was seen in two, and tuberculous infection in another two. In three cases leptomeningeal contrast enhancement was due to lymphoma. Human immunodeficiency virus (HIV) myelitis was seen in two patients, presumed vacuolar myelopathy in two, toxoplasma myelitis in four, intramedullary lymphoma in one, and herpes myelitis in one. Familiarity with the various potential pathological entities that can affect the spine and spinal cord in the AIDS population and their imaging characteristics is crucial for initiation of further diagnostic tests and appropriate medical or surgical treatment.

Rupture of spinal dermoid tumors with spread of fatty droplets in the cerebrospinal fluid pathways.

Cranial and spinal MRI was carried out at 0.5 or 1.5 T in five patients with spinal dermoid tumours. Free fatty material was appreciated within the normally communicating cerebrospinal fluid pathways in all five cases and in one case fat droplets were also observed within a dilated central canal of the spinal cord. While dissemination of lipid within the subarachnoid space and ventricles is easily understandable, the presence of lipid droplets within the central canal is more difficult to explain, since the central canal is only potential in the adult. When a dermoid tumor is suspected, we recommend MRI of the entire central nervous system, to detect possible leakage of fat from rupture of a cystic portion of the tumour.

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA).

RATIONALE AND OBJECTIVES: The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system. METHODS: Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques. RESULTS: No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation. CONCLUSIONS: Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.

Blake's pouch cyst: an entity within the Dandy-Walker continuum.

Abnormal cerebrospinal fluid (CSF) collections within the posterior fossa are defined by the Dandy-Walker complex (DWC) and by arachnoid cysts (AC). The DWC includes the Dandy-Walker malformation (DWM), the Dandy-Walker variant (DWV) and the mega-cisterna magna (MCM). In addition, Tortori-Donati et al. added persistent Blake's pouch cyst (BPC) as an independent entity within the DWC. BPC represents a posterior ballooning of the superior medullary velum into the cisterna magna. All of these malformations are overlapping developmental anomalies characterized by varying degrees of malformation of the medullary vela, the cerebellar vermis and hemispheres, the fourth ventricle choroid plexus, the posterior fossa subarachnoid cisterns and the enveloping meningeal structures. We present two cases of persistent BPC detected in two adult women without history of gestational or subsequent growth problems. They underwent neuroradiological investigation because of headache and because of recurrent episodes of loss of consciousness, respectively. The MRI findings included tetraventricular hydrocephalus, wide communication of the fourth ventricle and the cystic posterior fossa (i.e. BPC), inferior posterior fossa mass effect with or without hypoplasia of both the cerebellar vermis and the medial aspects of the cerebellar hemispheres, and absence of communication between fourth ventricle and the basal subarachnoid space in the midline posteriorly. Persistent BPC is defined by a failure of embryonic assimilation of the area membranacea anterior within the tela choroidea associated with imperforation of the foramen of Magendie. Typically this condition becomes symptomatic early in life. In the current cases the normal function of the laterally positioned foramina of Luschka probably helped to maintain some CSF flow between intraventricular and subarachnoid spaces, with the establishment of a precarious equilibrium characterized by a compensatory enlargement of the cerebral ventricular system (i.e. hydrocephalus).

Imaging of cranial meningitis and ventriculitis.

A spectrum of infectious diseases may affect the cranial meninges. Contrast-enhanced MR imaging and fluid-attenuated inversion-recovery MR techniques are superior to contrast-enhanced computed tomography for detecting and characterizing most pathologic meningeal conditions. In patients with meningitis, a major role of medical imaging is to identify potential complications such as hydrocephalus, extra-axial mass-forming infectious collections, parenchymal infarcts related to arteritis, ventriculitis, and associated underlying parenchymal abscesses or granuloma formations. Early diagnosis of such complications may reduce the rate of morbidity and mortality in this group of patients.

Clinics in diagnostic imaging (45). Osmotic myelinolysis ( central potine myelinolysis).

A 65-year-old woman developed progressive neurological deterioration following rapid correction of hyponatremia. Magnetic resonance imaging showed T2 hyperintense areas in the central pons, basal ganglia and deep white matter, typical of osmotic myelinolysis (OM). Previously thought to be uniformly fatal, there are increasing reports of non-fatal cases of OM. The recognition and understanding of this entity is important to prevent or reduce the incidence of its occurrence, as there is no specific treatment once it develops. The clinical and radiological features of OM are reviewed.