Computed tomography and magnetic resonance imaging findings of solitary fibrous tumors in the pelvis: Correlation with histopathological findings

Objective

We aimed to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of pelvic solitary fibrous tumors (SFTs) and to improve the diagnostic efficacy for such tumors.

Methods

Six cases of pelvic SFTs confirmed by histopathology were analyzed retrospectively. Of the 6 patients, 4 had undergone CT scanning, and 2 had undergone magnetic resonance imaging. All the patients had undergone unenhanced and contrast-enhanced examinations, and 2 had also undergone dynamic CT enhancement examination. Image characteristics such as shape, size, number, edge, attenuation or intensity for each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors.

Results

All the 6 cases showed oval or rounded and well-defined masses. Unenhanced CT images showed heterogeneous masses with patchy, necrotic foci in 3 cases and homogeneous mass in 1 case. None of the tumors showed calcification. Contrast-enhanced CT images showed marked, heterogeneous enhancement in the first and second cases. Dynamic enhancement scan demonstrated mild homogeneous enhancement in the third case and mild prolonged, delayed enhancement and washout in the fourth case. T1-weighted MR images showed heterogeneous mild hypointense lesion with linear hyperintensity in 1 case, and homogeneous isointensity in the other. T2-weighted images showed heterogeneous mixed intensity in 1 case and mostly hyperintensive lesion with hypointense foci in another case. A case showed marked heterogeneous enhancement and another showed marked homogeneous enhancement on contrast-enhanced T1-weighted images.

Conclusion

Radiological findings of pelvic SFTs are variable and nonspecific. However, a well-defined, ovoid or rounded mass with hypointense on MR T2-weighted images and variable enhancement on CT and MR images may suggest the diagnosis of SFTs. Pelvic SFTs should be included in the differential diagnosis of regional tumors.     

Metastatic liver tumor from cystic ovarian carcinomas: CT and MRI appearance.

OBJECTIVE: The initial and follow-up CT and MRI images of ten patients with hepatic metastases from ovarian tumors were retrospectively analyzed to establish their features and sequential changes in appearance. MATERIALS AND METHODS: Ten patients with hepatic metastasis from ovarian tumors received initial and follow-up CT and MRI examinations. Six patients were followed up every two to three weeks before surgical tumor resection. Both CT and MR images were analyzed by two radiologists. RESULTS: A total of fourteen lesions were detected by CT and MRI in 10 patients. All 14 lesions were demonstrated as areas of marked hyperintensity on T2-weighted MRI. Eleven cyst-like tumors were demonstrated as round or oval low density lesions on CT and as areas of hypointensity on T1-weighted imaging. Three lesions were shown as solid masses with slightly low attenuation at the initial CT examination and slightly low or iso-intensity areas on T1-weighted imaging, and these lesions showed early peripheral globular enhancement and delayed enhancement on contrast-enhanced CT and MR imaging. Cystic formation was observed two to three weeks later after initial study in all the 3 solid lesions. Rapid subcapsular effusion, which showed obvious enhancement on delayed Gd-DTPA enhanced MR imaging, was observed in two patients. CONCLUSION: The hepatic metastatic tumor from cystic ovarian carcinoma may manifest as a well-defined cystic lesion or as a solid mass, and the solid mass shows delayed enhancement on contrast-enhanced CT and MR imaging. Furthermore, rapid cystic formation and rapid subcapsular extension is frequently seen.     

CT, MR, and Angiography Findings of a Solitary Fibrous Tumor of the Larynx: a Case Report

This report details the CT, MR, and angiography findings of a solitary fibrous tumor involving the larynx of a 34-year-old man. A precontrast CT scan revealed a well-defined isodense mass in the submucosal region of the supraglottic larynx. The tumor appeared as a mixed intensity lesion on the T1- and T2-weighted MR images. A T2-weighted MR image showed a central, round, and low signal intensity area within the mass. For both the CT and MR images, the mass demonstrated heterogeneous enhancement following the administration of contrast material. The angiography showed a hypervascular tumor with heterogeneous persistent staining.     

头颈部孤立性纤维瘤的影像学表现

目的：探讨头颈部孤立性纤维瘤(SFT)的影像特征,提高对该病的认识。方法回顾性分析10例经手术病理证实的头颈部 SFT 患者的 CT 和 MR 表现。10例均行 CT 平扫及双期增强扫描、2例行 MR 检查。结果10例病灶均表现为孤立的肿块,最大径20~115 mm,中位最大径约35.5 mm。肿瘤发生于眼眶2例、鼻腔鼻窦4例,腮腺、面颊、锁骨上区及枕部各1例。病变边界清楚8例、模糊2例,呈椭圆形7例,分叶状3例。CT 平扫呈等或稍低密度,其中4例密度均匀,6例密度不均匀(2例见多发囊变区,1例见结节状钙化灶)。增强后9例呈明显均匀(n=3)或不均匀(n=6)强化,1例呈轻度均匀强化。CT 双期增强强化模式包括快速强化缓慢廓清8例、快速强化快速廓清1例和延迟强化1例。与脑实质相比,T1 WI 呈均匀等信号1例,等、低混杂信号1例;T2 WI 呈均匀等信号1例,等、高混杂信号(多发囊变)1例;增强后分别呈均匀和不均匀显著强化。结论头颈部不均匀的富血供肿瘤要考虑到 SFT 的可能。瘤体 T2 WI 与脑实质相比呈等或稍低信号,CT 增强扫描明显强化,双期增强呈快速强化缓慢廓清的强化模式可能是有诊断价值的影像特点。     

Fibrous histiocytoma and fibrous tissue tumors of the orbit

Fibrous orbital tumors present clinically and radiographically in a broad spectrum ranging from a benign mass, to locally aggressive tumor, to invasive malignancy. Pathologic analysis and diagnosis are often challenging, usually based on a combination of light microscopy, immunohistochemistry, and electron microscopic findings. Some light microscopic and immunohistochemical findings, however, are relatively characteristic. A storiform or cartwheel pattern and vimentin staining are characteristic of fibrous histiocytoma. A herringbone pattern is usually found in fibrosarcoma. A "patternless pattern" and CD34 staining is found most commonly in solitary fibrous tumor. CT and MR imaging findings, as well as clinical presentation, in fibrous orbital lesions are often difficult to distinguish from those of other orbital masses, although there may be useful clues. Benign fibrous lesions are usually well-circumscribed and may chronically remodel bone, whereas more aggressive malignant fibrous tumors tend to have infiltrating margins and may destroy bone on CT or MR imaging. With malignant fibrous masses, enhancement patterns on CT or MR imaging may be more inhomogeneous, with avascular or necrotic nonenhancing regions. At MR imaging, benign lesions tend to be homogeneous on T1, T2, and postgadolinium T1-weighted images, whereas malignant soft tissue lesions may change their pattern from homogeneous on T1-weighted images to heterogeneous with low signal septations on T2-weighted images. Low T2 signal comprising part or all of a fibrous lesion correlates with dense collagen fibers, with a less cellular matrix. Areas of hyperintensity on T2-weighted images correspond with a more cellular matrix of fibroblasts and other cells. Calcification within a tumor, however, may give a similar appearance. Thus, if a lesion has predominantly low signal on T2-weighted images, or less specifically has low signal septations, then a fibrous orbital lesion with high collagen content may be ranked higher in the differential diagnosis (see Figs. 2E and 3B). When T2 signal is intermediate-to-high, then one has a difficult time narrowing the differential diagnosis. Radiographically, distinguishing these lesions from other fibrous orbital lesions, as well as from other varieties of orbital masses, is difficult. Differential diagnosis of fibrous orbital masses includes all the fibrous lesions described in this article, in addition to schwannoma (Fig. 7), neurofibroma (Figs. 4 and 8), hemangiopericytoma (Figs. 9 and 10), rhabdomyosarcoma, meningioma, lymphoma, and metastasis (Figs. 11 and 12). A history of prior orbital irradiation for retinoblastoma or other tumors may raise the possibility of radiation-induced secondary tumors, such as MFH, fibrosarcoma, and osteosarcoma. Determining the extent of orbital involvement remains the primary goal of the radiologist. The final diagnosis still rests with the pathologist.     

胸膜外孤立性纤维瘤的影像表现与病理对照研究

目的:分析总结胸膜外孤立性纤维瘤的影像表现及病理基础,提高诊断准确性。方法:回顾性分析30例经病理证实的胸膜外孤立性纤维瘤的CT、MRI表现。5例患者仅进行了CT检查,19例患者仅进行了MR检查,6例同时行CT和MR检查。结果:30例患者均为单发病灶,其中13例位于中枢神经系统,7例位于头颈部、6例位于腹盆腔、1例位于食管、1例位于乳腺、1例位于腹股沟、1例位于耻骨。病灶多呈类圆形或长圆形,部分病例可见分叶或形态不规则。CT平扫颅内病灶呈不均匀等低密度或均匀稍高密度,其余病灶CT平扫呈均匀软组织密度。头颈部病灶T₁WI呈较均匀等低信号,其余病灶T₁WI呈欠均匀等低信号,T₂WI信号混杂,可见等、低、高信号;15例病灶边缘或病灶内可见血管流空信号。增强扫描颅内病灶呈明显不均匀强化,其余病灶呈中度到明显不均匀强化,腹盆腔病灶可见渐进性强化;T₂低信号区可见强化,坏死囊变区未见强化。免疫组化可见CD34、STAT-6、VIM、CD99、 Bcl-2阳性。结论:胸膜外孤立性纤维瘤分布广泛,病理基础决定其信号...     

Solitary fibrous tumor of the orbit: CT and MR imaging findings

BACKGROUND AND PURPOSE:Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.MATERIALS AND METHODS:We retrospectively reviewed CT and MR images in 6 patients (2 men and 4 women), aged 18 to 51 years, with SFT proved on histologic examination located in and around the orbit. All patients underwent CT (including dual-phase CT in 3), and MR imaging was obtained in 3. We evaluated the imaging findings with emphasis on the location, size, margin, internal architecture, and pattern of enhancement of the lesion.RESULTS:All 6 lesions were found as a solitary, well-defined mass, ranging in size from 18 to 30 mm (mean, 24 mm). Three were located in the postseptal orbit, 2 in the lacrimal sac, and 1 on the lower eyelid. Compared with the cerebral cortex, all 3 lesions examined by MR imaging showed homogeneous isointense signal intensity on T1-weighted images and heterogeneous mixed isointense and hyperintense signal intensity on T2-weighted images. On visual inspection, all 6 lesions showed marked homogeneous (n = 4) or heterogeneous (n = 2) enhancement on postcontrast CT and MR images. In 3 patients examined with dual-phase CT, all lesions demonstrated rapid enhancement with early washout of contrast material.CONCLUSION:SFT might be included in the differential diagnosis of soft tissue masses in the orbit, if one sees a markedly enhancing mass showing the similar characteristics to those of the internal carotid artery on postcontrast CT or MR images.

Since the first report by Klemperer and Rabin¹ in 1931 as a primary spindle-cell tumor of the pleura, solitary fibrous tumor (SFT) has been recognized as a distinctive, though rare, pathologic entity that most commonly arises from the pleura and peritoneum. Although once thought to be mesothelial in origin, SFT is now considered a tumor of mesenchymal fibroblast-like cell origin, and there has been an increasing incidence of the tumor to be found in the extrapleural, extraserosal sites such as the lung, liver, breast, and meninges. It can also arise in the extracranial head and neck region such as the orbit, sinonasal cavity, salivary gland, thyroid gland, upper respiratory tract, and deep cervical spaces.^2–7Since the first report of 2 cases of orbital SFT in 1994,⁸ the orbit has become one of the common sites of the head and neck involved by the tumor, and more than 50 cases of orbital SFT have been reported mostly in the ophthalmologic and pathologic literature.^9–21 To our knowledge, however, systematic analysis of the imaging features of orbital SFT has seldom been reported in the radiologic literature. The purpose of this study was to describe the characteristic CT and MR imaging findings of 6 cases of patients with SFT of the orbit proved on pathologic examination.     

Giant cell tumors of the tendon sheath may present radiologically as intrinsic osseous lesions

The purpose of this study was to explain radiographic features of giant cell tumors of the tendon sheath (GCTTS), in particular, osseous extension, by correlating imaging findings with histology in order to increase the accuracy of radiological diagnosis. In a series of 200 consecutive osseous (pseudo) tumors of the hand, on radiography, six patients presented with an intrinsic osseous lesion caused by a histologically confirmed neighboring GCTTS. Available radiographs, computed tomography (CT), and contrast-enhanced magnetic resonance (MR) images were correlated with histology. Radiography showed osseous lesions consisting of well-defined cortical defects in four (one of whom also demonstrated cortical scalloping) and a slightly expansile, well-defined osteolytic lesion in two patients. MR obtained in four patients showed the extraosseous tumor invading/eroding bone and causing cortical scalloping (three and one patients, respectively). Extension depicted on MR was confirmed on the two available resection specimens. All lesions were polylobular (cauliflower or mushroom like) and neighbored tendon sheaths. Dense collagen and hemosiderin-loaded macrophages explained the high CT attenuation and the low MR signal intensity on T2-weighted images that was observed in all four MR and in all two CT scans. The high density of proliferative capillaries explained the marked enhancement observed in all four patients with gadolinium (Gd)-chelate-enhanced MR imaging. GCTTS is a soft tissue (pseudo) tumor that may invade bone and as a consequence mimick an intrinsic osseous lesion on radiographs. In such cases, specific MR and CT features that can be explained by histological findings can be used to suggest the correct diagnosis.     

MR imaging of solitary pulmonary lesion: emphasis on tuberculomas and comparison with tumors

The aim of this study was to determine whether solitary pulmonary tuberculoma and malignant tumor can be differentiated on the basis of magnetic resonance (MR) signal intensity. Twenty-eight patients with solitary pulmonary lesions were prospectively studied with MR imaging: T1-weighted, enhanced T1-weighted, proton density-weighted, and T2-weighted spin echo images were obtained. The confirmation methods used were computed tomography (CT)-guided biopsy in seven patients with lung cancer and four patients with tuberculosis; surgery in ten patients with lung cancer and five patients with tuberculosis; and laboratory data in two patients with tuberculosis. Morphologic features and MR signal intensity were examined in detail. As the test for detection of tuberculoma, signal difference on T2-weighted images was carefully analyzed. The signal intensity ratio of the nodule to thoracic muscle signal intensity was measured. The signal intensities obtained from the lung cancers and tuberculomas were variable on pre-and post-enhanced T1-weighted images and proton density-weighted images. Masses were hypointense in 2 of 17 patients with lung cancer and in 9 of 11 patients with tuberculoma on T2-weighted images (sensitivity 82%, specificity 89%, accuracy 87%). The mean signal intensity ratios of the tuberculomas to muscle were significantly lower than those of malignant tumors on T1-weighted, enhanced T1-weighted, proton density-weighted, and T2-weighted images (P < 0.0001). After gadolinium-DTPA enhancement, 2 malignant tumors and 7 tuberculomas showed a marginal rim enhancement pattern, whereas 15 malignant tumors and 2 tuberculomas revealed a diffuse enhancement. The results of MR imaging were consistent with those of CT in 84% of the patients. MR imaging is a helpful adjunctive method in terms of differentiating a tuberculoma from a malignant tumor.     

From the archives of the AFIP: Localized fibrous tumor of the pleura

Eighty-two localized fibrous tumors of the pleura (LFTP) were reviewed retrospectively for the clinical, pathologic, and radiologic findings. Forty-four women and 38 men ranged in age from 17 to 78 years (mean, 54.7 years). Sixty-four benign LFTP ranged in size from 2 to 30 cm (mean, 13.2 cm), and 18 malignant tumors ranged from 3 to 23 cm (mean, 14.4 cm). Forty-eight patients (60%) presented with symptoms. Radiographs of 76 patients demonstrated solitary masses occupying or extending into the inferior hemithorax (79%). Computed tomography (CT) of 78 lesions demonstrated lobular masses (83%) that formed at least one acute angle (96%) or only acute angles (65%) with the adjacent pleura. Heterogeneous lesion attenuation was documented in 88% of enhanced and in 68% of unenhanced CT scans. Contrast enhancement was common (62% of cases). Magnetic resonance (MR) imaging of 18 lesions demonstrated heterogeneous signal intensity on both T1- and T2-weighted images (78% and 83%, respectively). Multiplanar MR imaging allowed visualization of the diaphragm and documentation of an intrathoracic mass in all cases. LFTP are solitary lobular heterogeneous masses that occur in symptomatic adults and often affect the inferior hemithorax. Malignant lesions are radiologically indistinguishable from those with benign histologic characteristics. Radiographic and CT features characteristic of pleural location are typically absent.     

CT and MR imaging of localized amyloidosis

The localized form of amyloidosis affecting the head and neck region is rare. The characteristic features of localized amyloidosis appeared as multiple nodules on the tongue, lip, and cheek on computed tomography (CT) and magnetic resonance imaging (MRI). Contrast-enhanced CT scans represented this lesion as a marked nodular enhancement. MR features of this lesion appeared slightly low on T1-weighted images and slightly high on T2-weighted images compared with T1-T2 images of residual normal tongue. Time contrast intensity curves obtained from dynamic MRI rapidly increased to reach a plateau and gradually decreased during the late and delayed phases. MR findings suggest that such lesions might be comprised of fibrous tissue with abundant vessels. This report suggests that dynamic MRI might be helpful for diagnosing localized amyloidosis.     

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.     

Castleman disease of the neck: CT and MR imaging findings

Objective

To characterize the computed tomography (CT) and magnetic resonance imaging (MRI) findings of Castleman disease of the neck.

Methods

The imaging findings of 21 patients with Castleman disease of the neck were reviewed retrospectively. Of the 21 patients, 16 underwent unenhanced and contrast-enhanced CT scans; 5 underwent unenhanced and contrast-enhanced MRI scans.

Results

The unenhanced CT images showed isolated or multiple well-defined homogenous mild hypodensity lesions in fifteen cases, and a heterogeneous nodule with central areas of mild hypodensity in one case. Calcification was not observed in any of the patients. In five patients, MR T1-weighted images revealed well-defined, homogeneous isointense or mild hyperintense lesions to the muscle; T2-weighted images showed these as intermediate hyperintense. Sixteen cases showed intermediate to marked homogeneous enhancement on contrast-enhanced CT or MR T1-weighted images. Of the other five cases that underwent double-phase CT scans, four showed mild or intermediate heterogeneous enhancement at the arterial phase, and homogeneous intermediate or marked enhancement at the venous phase; the remaining case showed mild and intermediate ring-enhancement with a central non-enhanced area at the arterial and venous phases, respectively.

Conclusion

Castleman disease of the neck can be characterized as solitary or multiple well-defined, mild hypodensity or homogeneous intense lesions on plain CT/MR scans, and demonstrates intermediate and marked enhancement on contrast-enhanced CT/MR scans. On double-phase CT scans, Castleman disease often demonstrates mild enhancement at the arterial phase, and gradually uniform enhancement at venous phase. Double-phase enhanced CT or MRI may help to differentiate Castleman disease from other diseases.     

CT and MR imaging features of oral and maxillofacial hemangioma and vascular malformation

PURPOSE: To present CT and MR images and compare CT and MRI features of oral and maxillofacial hemangioma and vascular malformation. MATERIAL AND METHODS: The clinical materials consisted of nine vascular tumors from nine patients examined by both CT and MR scanners between November 1996 and March 2002. Both CT and MR images were retrospectively evaluated. The following features were evaluated: detectability of the lesion, border of the lesion, tumor margin, inner nature of the lesion, contrast between the lesion and surrounding tissues, degree of CT value or signal intensity of the lesion, enhancement of contrast medium, inner nature of the lesion after contrast medium injection, detectability of phleboliths and detectability of bone resorption. RESULTS: In two patients, we could not detect lesions in any of the CT images because of artifacts from the teeth and/or dental restorations. In contrast, we could detect all lesions on T2-weighted MR images and contrast enhanced T1-weighted MR images. On T2-weighted images with the fat suppression technique, tumors tended to show higher contrast compared to surrounding tissues. CONCLUSION: T2-weighted images with the fat suppression technique and contrast enhanced T1-weighted images with the fat suppression technique were very useful for the detection of vascular lesions. Observation from optional directions (axial, coronal and sagittal images) seemed appropriate for delineating the extension of the tumor. Phleboliths detectability on CT images was superior to that on MR images.     

Findings in primary hepatic carcinoid tumor: US, CT, MRI, and angiography.

Two asymptomatic patients with surgically proven solitary primary hepatic carcinoid tumors are reported. Ultrasonography showed hyperechoic masses containing multiple small cystic areas in both cases. On unenhanced CT, one tumor was of low density and one was isodense with multiple low density foci. One tumor showed marked retention of contrast medium on post-angiographic CT. Magnetic resonance imaging revealed low intensity masses on T1-weighted images and high intensity tumors with multiple areas of higher intensity on T2-weighted imaging. The small low density areas in these masses corresponded histopathologically to multiple vascular lakes. Late enhancement of the mass was presumed to correspond with proliferative fibrous tissue within the mass.     

Brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism: CT and MR imaging findings

We present a case of brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism. CT showed an expansile soft-tissue attenuation mass centered in the sphenoid sinus. CT at bone window setting demonstrated expansile, lytic change and remodeling of the surrounding bone. On MR imaging, the lesion showed iso-intensity to gray matter on T1-weighted images and heterogeneous hyperintensity on T2-weighted images, and showed intense enhancement. The extent of the lesion and its relationship to the surrounding structures were best evaluated by CT and MR imaging.     

胚胎发育不良性神经上皮瘤的CT和MRI表现

目的:探讨胚胎发育不良性神经上皮瘤(DNET)的CT和MRI表现。方法:回顾性分析6例经手术病理证实的DNET的MRI和CT资料。6例均行常规MRI检查,其中4例行液体衰减翻转恢复(FLAIR)序列和扩散加权成像(DWI),3例行MR波谱检查。6例中5例行CT平扫。结果:6例中5例为单发,1例为弥漫性。病灶均位于或主要位于皮层区,单发者呈倒三角型表现。肿瘤以囊性成分为主,于CT平扫上均为低密度影,1例可见钙化;其MRI表现为T1WI低信号,T2WI高信号,FLAIR序列上病灶边缘和分隔呈高信号改变,增强扫描示病灶实质结节或分隔有轻度强化,病灶周围均未见水肿。结论:瘤周无水肿、倒三角征和瘤内分隔为PNET的特异性影像学表现,其影像学表现有助于临床诊断和治疗。     

Solitary fibrous tumor of the cerebellopontine angle: A case report with imaging analysis

Solitary fibrous tumors are rare mesenchymal neoplasms of the central nervous system. To date, only approximately 60 patients have been reported. Histological diagnosis is mainly based on immunohistochemical study which shows strong CD34 and vimentin reactivity of the cells. Pre-operative diagnosis remains a challenge to both neurosurgeon and radiologist since most of the imaging findings are thought to be non-specific. In addition, the role of post-operative radiotherapy and the long-term prognosis are both still unclear. Herein, we report a case with a cerebellopontine (C-P) angle solitary fibrous tumor. The imaging characteristics are described in detail. Further analysis and comparison with the imaging findings reported in the literature are also present. The tumor was homogeneous and isodense to brain parenchyma on pre-enhanced CT images and showed intense enhancement after contrast medium administration. In the MR study, the tumor revealed heterogeneous signal intensity on T2-weighted images and strong enhancement on post-contrast images. There were linear or curvilinear hypointensities which were less enhanced in the tumor on both T1- and T2-weighted images. This is a special feature which has been described. Moreover, serial images of dynamic enhancement disclosed a sharp rise of enhancement with a peak at 60 s followed by gradual decline. This pattern is the same as most meningothelial meningioma but different from fibrous meningioma and schwannoma. In addition to the imaging findings, we also noticed the good effect of post-operative radiotherapy for the residual tumor after subtotal resection. The patient was symptom-free with a stable residual tumor in a 2-year follow-up.     

Spinal angiolipomas: MR features.

PURPOSETo determine the MR features of spinal angiolipomas and to compare these findings with their histologic appearance.METHODSThe MR examinations of three patients with surgically proved angiolipomas were reviewed for tumor location and extent, signal characteristics, and pattern of contrast enhancement, and were then compared with the histologic findings.RESULTSFour tumors were found in the three patients, all located in the posterior epidural compartment, averaging about 2.5 vertebral bodies in length. On noncontrast T1-weighted images, all lesions were inhomogeneous and hypointense relative to epidural fat. Inhomogeneous enhancement was seen in three lesions on postcontrast T1-weighted images obtained with fat-saturation techniques. Angiolipomas were least conspicuous on T2-weighted images. A high vascular content correlated with the presence of large hypointense regions on T1-weighted images.CONCLUSIONSpinal angiolipomas are typically hyperintense on noncontrast T-1-weighted images relative to other tumors. Angiolipomas that contain large hypointense foci on noncontrast T1-weighted images can be expected to have a high degree of vascularity.     

Nerve sheath tumors: evaluation with CT and MR imaging.

Tumors of nerves are classified into benign (schwannoma and neurofibroma) and malignant nerve sheath tumors. Schwannomas almost always occur as solitary lesions, whereas neurofibromas may occur alone or in a greater number, especially in patients with the peripheral form of von Recklinghausen's disease. Benign nerve sheath tumors often present as asymptomatic, slowly growing soft tissue masses. Although malignant nerve sheath tumors are relatively rare, a sudden increase in the size of a lesion, in particular in a patient with neurofibromatosis, should raise the suspicion of malignant change. On computed tomography (CT) and magnetic resonance imaging (MR) a benign nerve sheath tumor usually appears as a well-defined, oval, spherical or fusiform mass with smooth borders and distinct outlines, located in the subcutaneous tissue or centered at the expected anatomic location of a nerve, with displacement of adjacent soft tissues. Generally nerve sheath tumors have a low density on unenhanced CT scans. On MR they are isointense to muscle on T1-weighted images, whereas on T2-weighted images the signal intensity is high. Both on CT and MR the degree of contrast enhancement is moderate to marked and may be homogeneous or inhomogeneous. MR has become the method of choice for evaluating the anatomic location, contour, and relation of a nerve sheath tumor to adjacent neural, vascular, and muscular structures. The imaging criteria for malignant nerve sheath tumors are not specific enough to distinguish them from other malignant soft tissue tumors, so that neither CT nor MR can establish a definite diagnosis.