颈椎后纵韧带骨化的CT诊断与临床分析

本文报告３９例颈椎后纵韧带骨化病症。临床表现为不同程度的脊髓损害，全部病例作了颈椎ＣＴ扫描，其中２０例进行脊椎造影ＣＴ检查，均显示有椎管狭窄及脊髓受压的征象，并对其病因、ＣＴ诊断价值进行了讨论。     

0.6 T MR imaging of the cervical spine: multislice and multiecho techniques

During a 6 month period, 50 patients with signs and symptoms referable to the cervical spine were studied with a 0.6 T superconducting magnetic resonance (MR) imaging unit. The last 23 of these 50 patients were studied with combined multislice and multiecho techniques. In 38 of the 50 patients, abnormalities were demonstrated on MR images. Intramedullary lesions included syringomyelia (three cases), primary tumors (two), metastatic neoplasm (one), cord atrophy secondary to trauma (one), and multiple sclerosis (one). Intradural, extramedullary lesions included two neurofibromas and two Chiari malformations. The rest of the lesions were extradural: degenerative changes (10), spinal stenosis with cord compression (five), disk degeneration and/or herniation (five), postoperative changes (four), metastases to bone/epidural disease (three), and neurofibromatosis (one). Two patients had more than one abnormality. The MR findings were compared with available routine radiographs, computed tomographic (CT) scans with and without metrizamide, and myelograms. MR imaging was consistently better than routine CT scanning in the detection of lesions of the spinal cord and in directly imaging the effects on the spinal cord of extrinsic abnormalities such as spinal stenosis. Metrizamide-enhanced CT scanning detected all cases of syringomyelia, but it involved an invasive procedure. Myelography alone was slightly less sensitive and considerably less specific than MR in detecting intramedullary lesions and in distinguishing cord neoplasms from syringomyelia. Multislice, multiecho techniques with up to 240 msec echo times (TEs) were particularly helpful in the detection and characterization of extradural processes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Radiologic imaging of symptomatic ligamentum flavum thickening with and without ossification

Thickening of the ligamenta flava with and without ossification in the thoracic and lumbar regions is a frequent finding on CT scanning; however, it is not widely appreciated as a possible primary cause of compressive cord, cauda equina, and nerve-root symptoms. We present observations from a series of seven patients whose symptoms were caused exclusively or largely by thickened ligamenta flava in the thoracic and lumbar regions. The findings were best demonstrated on myelography. One of our cases had been missed on previous MR, as would be expected with the null signal of calcification. CT scanning necessitates an extended window to ensure discrimination of an ossified ligament from thecal metrizamide. Thickened ligamenta flava are often found in conjunction with degenerative disease and spinal stenosis at multiple levels and should not be ignored as a possible major contributing factor to the patient's symptoms. In addition, those patients with a secondary block from a thickened ligamentum flavum should be studied from above with C1-C2 puncture to rule out other levels of clinically significant disease. Attention to the particular findings of thickened ligamenta flava is important since surgical intervention must involve removal of the entire offending ligament(s); otherwise clinical symptoms may not be relieved.     

MRI of the chronically injured cervical spinal cord

Thirteen patients with prior cervical spinal cord injury resulting in quadriplegia were evaluated with magnetic resonance imaging (MRI) long after their initial injury, either because of the relatively recent onset of new and worsening neurologic symptoms or to rule our residual compression on the spinal cord or nerve roots. The results of MRI were compared with delayed metrizamide computed tomography (CT) in 10 cases, and in five of those the results were also compared with intraoperative spinal sonography. It was found that MRI more accurately demonstrated the intramedullary abnormalities in the injured spinal cord than did delayed metrizamide CT because the former could separate myelomalacia from a posttraumatic spinal cord cyst, a differentiation that was frequently difficult with delayed metrizamide CT. T2-weighted spin-echo pulsing sequences with long echo times were particularly useful in evaluating these patients.     

Preoperative demonstration of postinflammatory syringomyelia

Syringomyelia secondary to arachnoiditis is a rarely reported entity, which has not been described in the radiographic literature. A series of eight patients who had either postinfectious, posthemorrhagic, iatrogenic, or idiopathic arachnoiditis was examined recently with metrizamide computed tomography (CT). These patients presented with progressive neurologic deficits that could not be attributed to the level of arachnoid changes on myelography. On immediate and/or delayed CT scans, metrizamide accumulation within the central part of the cord was identified, both at and above the level of the arachnoiditis. In some patients, the cord diameter was normal. Syrinx cavities were demonstrated and shunted at surgery with subsequent partial relief or arrest of the symptoms. The mechanism of development of postinflammatory syringomyelia is discussed.     

The value of computed tomographic metrizamide myelography in the neuroradiological evaluation of the spine

The diagnostic value of plain film metrizamide myelography (PFMM) was compared with computed tomographic metrizamide myelography (CTMM) in a study of 106 individuals who had undergone high-resolution computed tomographic scanning of the spine. CTMM provided more significant information than PFMM in 42 of 106 cases (40%), but showed no advantage over PFMM in 63 of 106 cases (59%). In 19 of the 42 cases (45%), PFMM was useful in directing the CT analysis to the appropriate region of pathology. In one patient, PFMM revealed a mobile herniated disc that had not been visualized with CTMM. In 30 of 106 cases in which plain CT scans of the spine were also obtained, the addition of intrathecal metrizamide demonstrated additional pathology in ten individuals. In general, CTMM was useful in the delineation of a variety of pathologic entities, especially neoplasms and congenital abnormalities. Low-dose CTMM (3 ml of a 150 ml/mg concentration) was performed as an outpatient procedure and found to be a useful adjunct to plain CT in two patients. A schema for the radiological evaluation of pathology of the spine is presented.     

Asymptomatic calcified herniated thoracic disks: CT recognition

Among 270 CT scans of the thorax obtained over a 7-month period, four patients (1.5%) with calcified herniated thoracic disks were identified. Each of these patients presented with abnormal chest radiographs and had a CT examination for evaluation of suspected malignancy. None showed any signs or symptoms of thoracic spinal cord compression. The clinical significance of incidental thoracic disk protrusions is unknown. It may be that these patients are at risk for the later development of symptomatic disk disease.     

Normal CT anatomy of the spine

Summary To analyse the anatomo-radiological correlation of the spine and spinal cord, 22 formalized, frozen anatomical specimens corresponding to different regions of the spinal column (8 cervical, 5 dorsal, and 9 lumbar) were studied by CT scans on axial, sagittal and coronal planes and by contact radiography after they were cut into anatomical slices in order to clarify the normal CT anatomical spinal column. The results obtained from CT patient scans, performed exclusively on the axial plane, were compared with those obtained from the anatomical specimens (both CT and contrast radiography). High resolution CT programs were used, enabling us to obtain better individualization of the normal structures contained in the spinal column. Direct sagittal and coronal sections were performed on the specimens in order to get further anatomo-radiological information. Enhanced CT studies of the specimens were also available because of the air already present in the subarachnoid spaces. Excellent visualization was obtained of bone structures, soft tissue and the spinal cord. High CT resolution of the spine appears to be an excellent neuroradiological procedure to study the spine and spinal cord. A metrizamide CT scan is, however, necessary when a normal unenhanced CT scan is insufficient for diagnosis and when the spinal cord is not clearly visible, as often happens at the cervical level. Clinical findings are certainly very useful to ascertain the exact CT level and to limit the radiation exposure.     

CT myelography and MR imaging of acute transverse myelitis

Two patients with acute transverse myelitis were evaluated by both CT myelography and magnetic resonance. Computed tomographic myelography showed fusiform cord enlargement involving several levels; one patient had a subtotal block in the thoracic spine. Magnetic resonance displayed similar findings of cord enlargement. The demonstration of cord swelling in acute transverse myelitis is an uncommon radiologic manifestation of the disease.     

MRI of cervical spine injuries complicating ankylosing spondylitis

OBJECTIVE: The objective was to study characteristic MRI findings in cervical spine fractures complicating ankylosing spondylitis (AS). Technical issues related to MRI are also addressed. MATERIALS AND METHODS: A review of 6,774 consecutive cervical spine multidetector CT (MDCT) scans obtained during 6.2 years revealed 33 ankylosed spines studied for suspected acute cervical spine injury complicating AS. Of these, 20 patients also underwent MRI. RESULTS: On MRI, of these 20 patients, 19 had a total of 29 cervical and upper thoracic spine fractures. Of 20 transverse fractures traversing both anterior and posterior columns, 7 were transdiskal and exhibited less bone marrow edema than did those traversing vertebral bodies. One Jefferson's, 1 atlas posterior arch (Jefferson's on MDCT), 2 odontoid process, and 5 non-contiguous spinous process fractures were detectable. MRI showed 2 fractures that were undetected by MDCT, and conversely, MDCT detected 6 fractures not seen on MRI; 16 patients had spinal cord findings ranging from impingement and contusion to complete transection. CONCLUSION: Magnetic resonance imaging can visualize unstable fractures of the cervical and upper thoracic spine. Paravertebral hemorrhages and any ligamentous injuries should alert radiologists to seek transverse fractures. Multiple fractures are common and often complicated by spinal cord injuries. Diagnostic images can be obtained with a flexible multipurpose coil if the use of standard spine array coil is impossible due to a rigid collar or excessive kyphosis.     

Conventional and CT metrizamide myelography in Arnold-Chiari I malformation and syringomyelia

Four normal controls and 26 cases of Arnold-Chiari I malformations and/or syringomyelia were reviewed. The pathologic cases included five isolated Arnold-Chiari I malformations, nine communicating syringomyelia, five idiopathic syringomyelia, four posttraumatic syringomyelia, one syringomyelia with hemangioblastoma, and two postshunt syringomyelia. The objectives of this study were to compare the accuracy of conventional metrizamide myelography with CT metrizamide myelography and to study indirectly the hydrodynamics of CSF flow in syringomyelia by comparing the sequential enhancement patterns of the spinal cords and cord cavities in the different groups of patients. Twenty-five patients underwent conventional metrizamide myelography immediately before CT metrizamide myelography, and one patient underwent CT metrizamide myelography only. Scans were obtained 1-2 hr, 4-8 hr, and 12-24 hr after injection of metrizamide, but not all patients were scanned during all three intervals. CT metrizamide myelography was found to be more sensitive than conventional metrizamide myelography in the diagnosis of both Arnold-Chiari I malformation and syringomyelia. Performing just an immediate and a delayed scan was found to be more cost-effective than doing all three scans. Contrary to previous reports, it was found that delayed (12-24 hr) scans demonstrated more syrinx cavities than intermediate ones. In studying the sequential enhancement patterns of the spinal cords and cord cavities, some interesting trends were observed that tend to support the theories of Aboulker and of Ball and Dayan of transneural passage of CSF into cord cavities in syringomyelia.     

Cervical chordoma presenting with intervertebral foramen enlargement mimicking neurofibroma: CT findings

A cervical chordoma, confirmed at surgery, presented on plain spine films as a focal enlargement of the intervertebral foramen and mimicked the characteristic appearance of cervical neurofibroma. Computed tomography (CT) of the cervical spine was obtained immediately following metrizamide myelography; it demonstrated a soft-tissue mass in the enlarged intervertebral foramen that extended posteriorly to compress the spinal cord and anteriorly to compress the hypopharynx. The mass was sharply demarcated, inhomogeneous, and low in attenuation; CT density measured between those of cerebrospinal fluid and muscle. Although this CT appearance is not specific for cervical chordoma, it is unusual for neurofibroma. Cervical chordoma should be considered in the differential diagnosis of focal enlargement of cervical intervertebral foramina.     

Thoracic disc disease and stenosis

Disc herniation and stenosis in the thoracic spine are relatively uncommon compared with their occurrence in the cervical or lumbar spine. They are usually degenerative, although trauma may be an aggravating or initiating factor. The clinical presentation includes local and/or radicular pain with or without signs and symptoms of cord dysfunction. Radicular pain may be secondary to mechanical compression or vascular impingement. MR imaging is the best way to define the specific abnormality as well as the effect on the adjacent spinal cord. CT after myelography may be useful as well, especially in those patients in whom there is involvement of the posterior ligamentous and osseous structures of the thoracic spinal canal. MR imaging may finally reveal the true incidence of thoracic disc herniation.     

Accidental introduction of contrast medium into the cervical spinal cord

Summary The density of metrizamide injected accidentally into the spinal cord during cervical CT myelography was measured with CT scanning and compared with a series of dilutions of metrizamide scanned with a special phantom. The test suggests that the metrizamide is diluted rapidly in the spinal canal, and in an accidental intraspinal injection of metrizamide, it is not the contrast medium itself but the mechanical effect of the introduction of a volume of fluid that causes the neurological symptoms.     

Posttraumatic syrinx formation: experimental study

An experimental study was performed to examine posttraumatic spinal cord cavitation in an animal model by evaluating immediate and delayed computed tomographic (CT) scans obtained after administration of intrathecal contrast material. Four cats underwent midthoracic laminectomy and spinal cord contusion using a standard 400 g-cm model. All animals were studied by CT with intrathecal contrast enhancement before and 4-5 days, 3-4 weeks, and 7-13 weeks after experimental cord contusion. Either metrizamide or iopamidol was used as the contrast agent. Two of the four cats had CT and pathologic evidence of cord cavitation at the site of injury. Another animal had uptake of contrast material into the spinal cord without pathologic evidence of cyst formation, which was believed to represent malacic change. The fourth animal had a normal-appearing cord by both CT and pathologic criteria. Animals that received metrizamide after cord contusion had generalized myoclonic seizures. This did not occur when iopamidol was administered.     

Measurement of trabecular bone mineral density in the thoracic spine using cardiac gated quantitative computed tomography

OBJECTIVES: To develop a method and evaluate the performance of thoracic bone mineral density (BMD) measurement using cardiac gated quantitative computed tomography (QCT). METHODS: A total of 762 participants (57% female) with a mean age of 61 years had a CT examination of the heart using prospective cardiac gating. A subset of 443 participants had replicate CT examinations of the heart. Another, nonindependent subset of 464 participants had CT examination of the abdomen. A QCT calibration phantom was included in all scans. Trabecular BMD was measured in the thoracic (T6-T11) and lumbar (T11-L4) spine. Tests of calibration and refinement and simple correlations between replicate thoracic BMD measurements and between thoracic and lumbar BMD measurements were calculated. RESULTS: There was high correlation between replicated thoracic BMD measurements in men (r = 0.995, P < 0.0001) and in women (r = 0.995, P < 0.0001). There was high correlation between thoracic and lumbar BMD in men (r = 0.90, P < 0.0001) and in women (r = 0.94, P < 0.0001). The mean BMD was higher in the thoracic spine than the lumbar spine in men (137.58 mg/cm3 vs. 126.94 mg/cm3, P < 0.0001) and in women (152.07 mg/cm3 vs. 133.44 mg/cm3, P < 0.0001). In both genders, thoracic and lumbar BMD was inversely associated with age (all P < 0.05). CONCLUSIONS: Cardiac gated CT, primarily intended for measurement of coronary vascular calcium, can be used to measure thoracic BMD with high precision. Thoracic BMD measurements using this method are highly correlated with QCT measurements in the lumbar spine.     

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.     

MR imaging of syringomyelia and hydromyelia

The relative effectiveness of plain computed tomography (CT), metrizamide CT, conventional myelography, and magnetic resonance (MR) imaging was compared for the examination of cystic spinal cord lesions. Intramedullary cavities in 18 patients were demonstrated by MR imaging: cavities were uncomplicated in 13 patients, associated with spinal tumors in two, and studied after occipital craniectomy for treatment of Chiari malformation and syringomyelia in two. Cavities were shown by MR imaging in all enlarged spinal cords, but a cavity was shown in only one of four small cords. The rostral limits of the cavities were demonstrated better than were the caudal extensions. Ventricular communication was not demonstrated. Chiari malformation was shown only in cavities that did not involve the medulla. Syringes associated with tumor were indistinguishable from uncomplicated cavities, but the tumor had abnormal signal on long spin-echo sequences in two cases. Cystic cord tumor (one case) had an inhomogeneous appearance. Caudal displacement of the cerebellar hemisphere through the surgical defect associated with compression of the fourth ventricle was shown in two cases after posterior fossa craniectomy. Thirteen patients were studied with metrizamide CT also. MR imaging proved to be as accurate as metrizamide CT in the diagnosis of intramedullary cavities that result in spinal cord enlargement, but it was less sensitive in detecting cavities within normal-sized or diminished spinal cords. It had the advantage that tumor tissue could be distinguished from associated syrinx cavities by differences in signal characteristics; and cerebellar ectopia was evaluated easily on sagittal MR views.     

Intraoperative spinal sonography: adjunct to metrizamide CT in the assessment and surgical decompression of posttraumatic spinal cord cysts

Ten patients with prior spinal cord trauma were examined preoperatively by metrizamide computed tomography (CT) and were studied subsequently by intraoperative spinal sonography. On comparing intraoperative sonography with metrizamide CT, it was found that metrizamide CT tends to overestimate the size and number of posttraumatic cysts, that areas of myelomalacia on metrizamide CT correspond to areas of abnormal echogenicity on intraoperative sonography, and that intracyst septations are seen only on intraoperative sonography. By monitoring the position of the shunting catheter during surgery, intraoperative sonography can assure its proper intramedullary placement and demonstrate the successful decompression of the cyst. If no cyst is found with intraoperative sonography, further surgery is obviated. Intraoperative sonography is recommended for all cases where decompression of cord cysts is planned.     

Radiologic evaluation of spinal cord fissures

The clinical course and radiographic studies were reviewed of eight patients with posttraumatic spinal cord fissures (rents in the spinal cord communicating with the subarachnoid space). Five patients had spinal cord fissures associated with symptomatic intramedullary cysts that required shunting to alleviate progressive neurologic deficits and intractable pain. Their metrizamide myelograms showed contrast medium passing immediately from the subarachnoid sac into the spinal cord and their immediate metrizamide CT scans delineated the entire extent of the secondary cord cysts. Intraoperative sonography confirmed the presence of the cord fissures with sizeable cysts, detected adhesions, and guided myelotomies and the subsequent shunting and collapse of the cysts. Since neurologic improvement followed the shunting procedures in all five patients treated for progressive symptoms, it was concluded that early radiologic evaluation of posttraumatic spinal cord fissures with symptomatic cord cysts is crucial in the clinical management of these patients.