Imaging of the spine and spinal cord

Recent technologic advances in MR imaging of the spine and spinal cord have been aimed at shortening examination time and suppressing artifacts. Gradient-recalled fast T2-weighted imaging is advocated for evaluating cervical radiculopathy. Better signal-to-noise ratios are achieved with three-dimensional Fourier transform gradient-recalled T2-weighted imaging and with decreased bandwidth acquisition. Obtaining high-contrast images of the spine is often complicated by the appearance of truncation artifacts. In outpatient radiculography, both iopamidol and iohexol appear safe, but iohexol seems better tolerated. In trauma, MR imaging is definitive, and signal abnormalities can help in evaluating neurologic recovery. Intraoperative spinal sonography may be helpful in evaluating acute injury. Enhancement with gadolinium diethylenetriamine penta-acetic acid is useful in the evaluation of disk space infections, osteomyelitis, and epidural abscess and in the study of spinal cord sarcoidosis. In patients with the acquired immunodeficiency syndrome, MR imaging may show hyperintense spine on T2-weighted images. MR imaging with gadolinium diethylenetriamine penta-acetic acid or gadolinium tetra-azacyclododecane tetra-acetic acid enhancement can be useful in evaluating intramedullary and intradural extramedullary tumors and for determining the extent of spinal leptomeningeal metastases. MR imaging can also be used to differentiate benign from pathologic fractures.     

MR imaging of intraspinal tumors—Capability in histological differentiation and compartmentalization of extramedullary tumors

Summary Magnetic resonance (MR) images of 29 consecutive patients with intraspinal neoplasms (9 intramedullary tumors, 20 extramedullary tumors) were reviewed to evaluated the utility of MR imaging in distinguishing the intraspinal compartmental localisation and signal characteristics of each lesion. Compartment and histology of all neoplasms were surgically proven. MR correctly assigned one of three compartments to all lesions, 9 intramedullary, 14 intradural extramedullary (6 schwannomas, 3 neurofibromas, 5 meningiomas), and 6 extradural (3 schwannomas, 1 meningioma, 1 cavernous hemangioma, 1 metastatic renal cell carcinoma). All intramedullary tumors showed swelling of the spinal cord itself. In all five extradural tumors a low intensity band was visualized between the spinal cord and tumor. On the other hand, a low intensity band was demonstrated in no cases with intradural tumors. Visualization of this low intensity band is important in differentiating extradural from intradural-extramedullary lesions. We call this low intensity band, the extradural sign. Signal intensity of intradural tumors varied with histology. In extramedullary tumors, signal intensity of schwannomas was similar to that of the cerebrospinal fluid (CSF) both on T1 weighted (inversion recovery) and T2 weighted spin echo (SE) images. On the other hand, meningiomas tended to be isointense to the spinal cord on both T1 and T2 weighted SE images. We found relatively reliable signal characteristics to discriminate meningioma from schwannoma.     

Neoplasms of the spinal cord and filum terminale: radiologic-pathologic correlation.

Intramedullary spinal cord neoplasms are rare, accounting for about 4%10% of all central nervous system tumors. Despite their rarity, these lesions are important to the radiologist because magnetic resonance (MR) imaging is the preoperative study of choice to narrow the differential diagnosis and guide surgical resection. On contrast materialenhanced MR images, intramedullary spinal tumors almost always manifest as expansion of the spinal cord and show enhancement. Syringohydromyelia and cystic lesions are frequently associated with intramedullary tumors. Nontumoral cysts tend to be located at the poles of the tumors and do not enhance on contrast-enhanced MR images, whereas cysts within the substance of the tumor are considered tumoral cysts and typically demonstrate peripheral enhancement. Spinal cord ependymomas are the most common type in adults, and cord astrocytomas are most common in children. Both entities constitute up to 70% of all intramedullary neoplasms. A central location within the spinal cord, presence of a cleavage plane, and intense homogeneous enhancement are imaging features that favor an ependymoma. Intramedullary astrocytomas are usually eccentrically located within the cord, are ill defined, and have patchy enhancement after intravenous contrast material administration. Even with these characteristics, it may not be possible to differentiate these two entities on the basis of imaging features alone. Cord hemangioblastomas are the third most common type of intramedullary spinal tumor. Gangliogliomas commonly extend over more than eight vertebral segments. Paragangliomas and primitive neuroectodermal tumors have an affinity for the filum terminale and cauda equina. Other spinal cord tumors include metastatic disease, which is characterized by prominent cord edema for the size of the enhancing portion, and primary lymphoma.     

Application of turbo fluid-attenuated inversion-recovery MRI in evaluation of intraspinal tumors

PURPOSE: Although fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) is widely applied to diagnose central nervous system diseases, its role in diagnosis of intraspinal tumors is unclear. In this study, we evaluated the potential clinical application of a turbo FLAIR sequence for imaging of intraspinal tumors. MATERIALS AND METHODS: Forty-eight consecutive patients with intraspinal tumors underwent MRI with turbo FLAIR and turbo spinal echo (TSE) sequences. Turbo FLAIR images were then qualitatively and quantitatively compared with T2-weighted TSE images. RESULTS: Turbo FLAIR images were evaluated as superior to T2-weighted TSE images for image artifact, extradural tumor conspicuity, and intradural extramedullary tumor conspicuity and detection. Intramedullary tumor conspicuity with turbo FLAIR was less than T2-weighted TSE. Similar capabilities in detection of extradural and intramedullary tumors were found between turbo FLAIR and T2-weighted TSE. Turbo FLAIR and T2-weighted TSE displayed similar normal spinal cord signal-noise ratio (SNR) and tumor-to-cerebrospinal fluid (CSF) contrast-to-noise ratio (CNR). In addition, turbo FLAIR yielded significantly higher tumor-to-CSF contrast than T2-weighted TSE. However, tumor SNR, tumor-to-normal spinal cord contrast and CNR with turbo FLAIR images were lower than those with T2-weighted TSE images. CONCLUSION: This study demonstrated (a) a superiority of turbo FLAIR to T2-weighted TSE in displaying and detecting intradural extramedullary tumors, (b) a superiority of turbo FLAIR to T2-weighted TSE in demonstrating extradural tumors, and (c) less usefulness in displaying intramedullary tumors with turbo FLAIR than with T2-weighted TSE.     

Gd-DTPA-enhanced MR imaging of spinal tumors

Forty-eight Gd-DTPA-enhanced MR examinations of the spine were performed in 40 patients referred for MR because of clinically suspected spinal tumor or for further evaluation of an expanded cord. The study group consisted of 32 patients with spinal tumors (seven ependymomas; seven astrocytomas; four hemangioblastomas; two arteriovenous malformations; two unidentified intramedullary neoplasms; four meningiomas; and single cases of metastatic breast carcinoma, cavernous hemangioma with associated hematomyelia, neurinoma, angiolipoma, drop metastasis from medulloblastoma, and epidermoid with diastematomyelia). In the remaining eight patients, other diagnoses were established: thoracic disk herniation (two patients), lumbosacral meningocele (one), syringomyelia secondary to arachnoiditis (four), and expanded cord secondary to gliotic tissue (one). All but two diagnoses were proved histologically by biopsy, surgery, or autopsy; in the two patients with arteriovenous malformations, the definitive diagnosis was made by spinal angiography. Contrast enhancement occurred in 30 of the 32 spinal tumors, and Gd-DTPA-enhanced T1-weighted images proved helpful in defining and outlining intra- and extramedullary spinal neoplasms. All ependymomas and astrocytomas (including low-grade astrocytomas) enhanced. In meningiomas, an immediate and uniform contrast uptake was demonstrated. Additional advantages of Gd-DTPA MR include the differentiation of solid tumor components vs syrinx or cyst or pseudotumoral areas of cord expansion, and the differentiation of residual or recurrent tumor from scar tissue in postoperative patients. Our results suggest that IV-injected Gd-DTPA improves MR sensitivity and specificity in the evaluation of spinal lesions.     

Intradural schwannomas of the spine: MR findings with emphasis on contrast-enhancement characteristics.

Intradural extramedullary schwannomas are nerve sheath neoplasms that consist of focal proliferations of Schwann cells involving a spinal nerve. We reviewed the MR findings in seven patients with pathologically proved intradural schwannomas. The contrast-enhancement characteristics on MR images were determined and compared with the histologic features of the tumor. Six lesions were variably hyperintense on T2-weighted images and one was uniformly hypointense compared with the signal intensity of the spinal cord. Signal on T1-weighted images ranged from hypointense to isointense. All seven tumors showed heterogeneous enhancement; in five, the enhancement involved only the periphery of the lesion. The pattern of enhancement did not correlate with the signal characteristics noted on unenhanced T1- and T2-weighted images. Pathologically, hyaline thickening of vessel walls and cyst formation were prevalent in the peripherally enhancing lesions. However, enhancement did not correlate with the relative proportion of Antoni type A and type B tissue. Recognition of the MR characteristics of intradural extramedullary schwannomas may be helpful in the differential diagnosis of spinal tumors. In particular, peripheral contrast enhancement of an intradural extramedullary tumor on MR images should suggest the diagnosis of schwannoma.     

Spinal intradural tumors

Spinal intradural tumors are uncommon lesions but may cause significant morbidity. In establishing the differential diagnosis for a spinal lesion, location, age, and the patient's clinical presentation are important. Magnetic resonance imaging plays a central role in the visualization of spinal tumors, easily allowing tumors to be classified as extradural, intradural extramedullary, or intramedullary which is very useful in tumor characterization. We describe intradural tumors; the majority is extramedullary, with nerve sheath tumors being the most frequent. Intramedullary tumors are uncommon spinal tumors. Ependymomas and astrocytomas comprise the majority of this group. Typical imaging features of both intradural extramedullary and intramedullary tumors are described.     

Magnetic Resonance Imaging Characteristics of Primary Intraspinal Peripheral Primitive Neuroectodermal Tumour

Purpose

The purpose of our study was to describe the salient magnetic resonance imaging (MRI) findings in primary intraspinal peripheral primitive neuroectodermal tumour (PNET).

Methods

A retrospective review of the clinical and MRI images of 7 pathologically proven cases of intraspinal peripheral PNETs was performed. The various parameters, such as vertebral level of involvement; tumour location, size, focality, and margin; signal intensity of the lesion; the presence of hemorrhage or calcification; any signal voids; assessment of the adjacent cord for cord compression; cord dilatation; the presence of paraspinal tissue mass; or vertebral or other bony changes, were analysed.

Results

All 7 patients had lesions in the thoracolumbar region. Three patients had extradural lesions, 4 had intradural extramedullary lesions, and none had intramedullary lesions. Six lesions were well circumscribed. Only 1 patient had multifocal involvement. All lesions were of hypointense or isointense signal on T1-weighted imaging, whereas all but one were hyperintense on T2-weighted imaging. Lesions enhanced heterogeneously except 1 intradural extramedullary lesion, which enhanced homogeneously. A paraspinal mass was noticed in 2 patients. Vertebral collapse was present in 1 patients.

Conclusion

Intraspinal peripheral PNETs are rare spinal tumours. Although imaging characteristics are not specific, a focal circumscribed lesion in a young individual at the intramedullary, extramedullary intradural, or extradural spinal location that shows hypointense and hyperintense signal on T1- and T2-weighted images, respectively, requires PNET to be considered in the differentials.     

MR imaging of intradural inflammatory diseases of the spine

Twenty-eight patients with intradural inflammatory disease of the spine were studied in order to characterize the MR imaging findings of infectious and inflammatory conditions. Patients were categorized according to the spinal compartment involved. Among the 12 patients in the intradural extramedullary group, unenhanced scans were either normal or nonspecific while contrast-enhanced scans were helpful in visualizing and localizing the lesion. Nevertheless, contrast-enhanced MR studies were unable to differentiate infection and inflammation from tumor in this compartment. Among 16 patients with intramedullary lesions, four had granulomatous disease and 12 had nongranulomatous disease. The granulomatous lesions resembled tumors and displayed MR characteristics of a focal lesion with large nodular enhancement. The patients with nongranulomatous intramedullary lesions exhibited two subsets of MR findings. In the first subset of nine patients, diffuse cord swelling and high signal were seen on long TR images, combined with either no enhancement or peripheral, diffuse, or speckled enhancement of the spinal cord on contrast-enhanced short TR images. In the second subset of three patients, minimal or no spinal cord swelling was displayed despite the visualization of high signal on long TR scans and nodular enhancement with contrast administration on short TR scans. Both subsets were sufficiently unique that nongranulomatous myelitis could usually be differentiated from spinal cord tumors.     

Spinal intradural capillary hemangioma: MR findings

We report a case of a spinal intradural capillary hemangioma. On MR images, a well-circumscribed intradural mass was detected at the T8-T9 level. The signal intensity of the mass relative to the spinal cord was isointense on T1-weighted images, hyperintense on T2-weighted images, and showed homogeneous, strong enhancement on contrast-enhanced T1-weighted images. The mass had both extramedullary and intramedullary components.     

椎管内血管性病变的MRI诊断

目的 总结不同类型椎管内血管性病变的影像特点,以提高对该类疾病的诊断水平. 资料与方法 对33例经手术病理或DSA证实的椎管内血管性病变的影像及临床资料进行回顾性分析,其中海绵状血管瘤11例(髓内8例,髓外硬脊膜外3例),血管母细胞瘤4例(单发2例,多发2例),动静脉病变18例(动静脉瘘12 例,动静脉畸形6例).所有病例均行MR平扫和增强扫描. 结果 椎管内血管性病变好发年龄在40岁左右,临床多表现为渐进性的神经系统受损症状.海绵状血管瘤髓内较髓外相对多见,髓内病变颈段好发,病变多局限,病灶周围T2低信号环较具特征性,强化多不明显;硬脊膜外海绵状血管瘤少见,多发生在胸段,常为边界清楚梭型肿物,均匀明显强化.血管母细胞瘤较少见,可单发亦可多发,多发生在颈、胸段,当伴有较大范围脊髓空洞或囊变,并有明显强化结节时,诊断不难;动静脉病变最多见, MRI多能发现蜿蜒血管流空信号,较易诊断,但具体分型有赖于DSA或手术. 结论 椎管内不同类型的血管性病变具有相对特异的影像表现,MRI可较好地显示病变,并能准确定位,同时可以显示脊髓变性的程度和范围,有利于病变的诊治及判断预后.     

MR imaging of intradural extramedullary tumors.

Thirty-one consecutive intradural extramedullary spinal tumors examined with MR at 0.3 T were reviewed. In 13 of the patients myelography had been performed. There were 11 patients with meningeoma, 14 with neuroma, one ependymoma, 3 metastases, and 2 lipomas. All tumors were surgically removed and verified by histology. The intradural extramedullary location of the tumors was accurately assessed by MR imaging in all patients and by myelography in 10 of 13. The MR diagnoses were in accordance with the histologic findings in 74% of cases. Compression of the spinal cord or cauda equina with widening of the subarachnoid space above and below the mass or outward displacement of epidural fat was characteristic of the intradural extramedullary tumors. The signal intensity of meningeoma as well as of neuroma was slightly lower or equal to that of the cord on T1-weighted images, and equal to or higher than cord signal on T2-weighted images. Neuroma had a lower signal intensity on T1-weighted images and a higher signal intensity on T2-weighted images than meningeoma. Meningeoma appeared more homogeneous than neuroma and had a broad base towards the dura.     

Importance of absence of CSF pulsation artifacts in the MR detection of significant myelographic block at 1.5 T

MR imaging was performed on 21 patients who had high-grade myelographic block due to various diseases in all spinal compartments (extradural, intradural/extramedullary, and intramedullary) and in all portions of the spinal canal (cervical, thoracic, and lumbosacral). Loss of CSF pulsation artifacts due to significant compression of the spinal cord was demonstrated on non-motion-compensated T2-weighted examinations in each case. We believe that the absence of such artifacts on these sequences indicates significant spinal cord compression in patients without classic signs and symptoms of cord compression but with intraspinal disease identified on T1-weighted studies.     

Spinal intradural extramedullary capillary hemangioma: MR imaging findings

SUMMARY: Spinal intradural extramedullary capillary hemangiomas are extremely rare. We present the MR imaging and histologic findings in three patients with this abnormality. The three patients were men who had symptoms of either myelopathy (n = 2) or radiculopathy (n = 1). The tumors were well demarcated, 1.5-2.0 cm in diameter, and were located at the posterior or posterolateral portion of the thecal sac (one at the L1 level and the other two at the midthoracic level). On MR images, the tumor showed isointensity relative to the spinal cord on T1-weighted images, hyperintensity on T2-weighted images, and strong homogeneous enhancement on contrast-enhanced T1-weighted images in all three patients. In two patients, the dural tail sign was observed. Capillary hemangioma should be included in the differential diagnosis of a spinal intradural extramedullary tumor.     

Radiological findings of spinal schwannomas and meningiomas: focus on discrimination of two disease entities

This study evaluates the effectiveness of CT and MR imaging in differentiating intradural extramedullary spinal schwannomas and meningiomas in a large group of patients. In addition, the study correlates tumour location, morphologic characteristics and enhancement pattern. From January 2000 to June 2007, we retrospectively reviewed 128 consecutive patients (51 male, 77 female; mean age at admission 53.8 years; range 17–83 years) with spinal intradural extramedullary tumours (92 schwannomas, 36 meningiomas) at our institution. Fifty-one of ninety-two schwannomas (55.4%) showed fluid signal intensity on T2-weighted MR images. Twenty-two of thirty-six meningiomas (61.1%) showed hyperintense signal intensity and thirteen of thirty-six meningiomas (36.1%) showed isointense signal on T2-weighted MR images. Fifty-four schwannomas (58.7%) showed rim enhancement and thirty-three meningiomas (91.7%) showed diffuse enhancement on contrast-enhanced T1-weighted MR imaging. Twenty-one meningiomas (58.3%) showed dural tail sign in contrast-enhanced T1-weighted MR imaging. Twenty-one meningiomas (58.3%) showed calcification on CT images. MR and CT imaging results are therefore useful for the differentiation of schwannomas from meningiomas of the spine.     

Spinal cord tumors

Spinal cord tumors are rare; however, every radiologist should be able to recognize and readily identify those lesions often found in younger patients or children [1, 2, 3, 4, 5, 6, 7, 8,9]. Early diagnosis plays an important role in the management of the lesions and interferes with the prognosis and final outcome of the patient [10]. Plain X-ray of the spine and CT are of limited diagnostic value in cases of intramedullary pathology. Magnetic resonance imaging should be performed as soon as possible and as the first technique whenever an intrinsic spinal cord lesion is clinically suspected. Systematic analysis of the MR images together with a basic knowledge of the most common spinal cord tumors encountered, including astrocytomas, ependymomas, and hemangioblastomas, should provide a correct diagnosis and lead to appropriate treatment subsequently.     

MRI of high-grade astrocytic tumors: early appearance and evolution

The clinical management and prognosis of patients with diffusely infiltrating astrocytomas are dependent on neuropathological grading of the tumors. The characteristics of MR images of high-grade astrocytic tumors are well known, but the early MRI appearance and the MRI evolution of high-grade astrocytic tumors have rarely been examined. We retrospectively reviewed MR images obtained from 4 months to 3 years and 3 months before admission, as well as MR images on admission, for five patients with pathologically proven high-grade astrocytic tumors (two glioblastomas and three anaplastic astrocytomas). In two patients, neoplastic lesions were not detectable on initial MRI, even retrospectively. In the remaining three patients, however, hyperintense areas with little or no mass effect were demonstrated on T2-weighted imaging. These lesions were misinterpreted as non-neoplastic processes, such as ischemic lesion or infarction, or demyelinating processes. All tumors showed gadolinium enhancement on admission, that emerged from the previously existing hyperintense areas on T2-weighted images without gadolinium enhancement, except for one de novo glioblastoma. Development of a small central cyst without gadolinium enhancement was demonstrated in one case before the emergence of an enhancing area.     

Spinal tumors

Spinal tumors are uncommon lesions but may cause significant morbidity in terms of limb dysfunction. In establishing the differential diagnosis for a spinal lesion, location is the most important feature, but the clinical presentation and the patient's age and gender are also important. Magnetic resonance (MR) imaging plays a central role in the imaging of spinal tumors, easily allowing tumors to be classified as extradural, intradural-extramedullary or intramedullary, which is very useful in tumor characterization. In the evaluation of lesions of the osseous spine both computed tomography (CT) and MR are important. We describe the most common spinal tumors in detail. In general, extradural lesions are the most common with metastasis being the most frequent. Intradural tumors are rare, and the majority is extramedullary, with meningiomas and nerve sheath tumors being the most frequent. Intramedullary tumors are uncommon spinal tumors. Astrocytomas and ependymomas comprise the majority of the intramedullary tumors. The most important tumors are documented with appropriate high quality CT or MR images and the characteristics of these tumors are also summarized in a comprehensive table. Finally we illustrate the use of the new World Health Organization (WHO) classification of neoplasms affecting the central nervous system.     

Gadolinium-DTPA in the evaluation of intradural extramedullary spinal disease

Gadolinium-DTPA was used in MR imaging of the spine to determine the ability of a contrast agent to increase the detection and characterization of disease in the intradural extramedullary space. Although MR imaging, especially with recent technological improvements, has been shown to be at least competitive with, and often superior to, myelography and postmyelography CT in the study of intramedullary and extradural disease, its use in the assessment of intradural extramedullary disease has been questioned. We selected 12 patients with intradural extramedullary disease as demonstrated by positive CSF cytology and/or myelographic findings and performed MR examinations on them before and after administering gadolinium-DTPA (0.1 mmol/kg). Gadolinium-DTPA was extremely effective in depicting intradural extramedullary disease of the spine. Small nodules of 3 mm, virtually invisible on noncontrast MR scans, enhanced strongly and were easily detected. In addition, leptomeningeal spread of tumor along nerve roots was also visualized, sometimes more readily than by myelography and postmyelography CT. The remarkable sensitivity of gadolinium-DTPA to intradural extramedullary disease assures its role in future MR examinations of the spine.     

Gadolinium-DTPA-Enhanced MR Imaging of Spinal Neoplasms: Preliminary Investigation and Comparison with Unenhanced Spin-Echo and STIR Sequences

Unenhanced T1- and T2-weighted spin-echo, short inversion time inversion recovery (STIR), and gadolinium-DTPA (Gd-DTPA)-enhanced spin-echo and STIR imaging techniques were used in 20 patients as part of a multicenter study to assess the safety and efficacy of Gd-DTPA in spinal imaging. Five patients had normal MR scans. Of those with lesions, both Gd-DTPA-enhanced T1-weighted spin-echo and unenhanced STIR scans improved detection and evaluation of spinal tumors over conventional spin-echo methods, particularly T2-weighted spin echo, by providing higher tissue contrast in shorter imaging times. The Gd-DTPA-enhanced T1-weighted spin-echo scans were most helpful in evaluating intradural tumors, whereas STIR sequences were most effective for extradural tumors and bone metastases. In most cases, Gd-DTPA-enhanced T1-weighted spin-echo scans best delineated tumor margins, and the enhancement was helpful in suggesting a cellular or active nature of the lesions. In some cases, the enhancement resulted in a more homogeneous and thus less abnormal-appearing marrow in vertebrae involved by tumor; therefore, a precontrast T1-weighted spin-echo scan is necessary in all patients who are to be studied with Gd-DTPA.A combined approach that uses T1-weighted spin-echo, Gd-DTPA-enhanced T1-weighted spin-echo, and STIR images currently appears optimal for MR imaging of spinal neoplasms. T2-weighted spin-echo images add information only in occasional cases.