四肢软组织神经鞘瘤的MRI诊断

目的 探讨MRI对四肢软组织神经鞘瘤的诊断价值.方法 回顾性分析12例经手术病理证实的四肢软组织神经鞘瘤的MR影像资料.全部病例均行常规MR扫描,应用T1WI、T2WI及脂肪抑制PDWI序列做轴面、冠状面和矢状面扫描,其中9例行T1WI增强扫描.结果 12例均表现为边界清楚的纺锤形或椭圆形肿块,沿神经走行方向生长,其中单发9例,多发3例.在T1WI呈稍高信号6例,等信号4例,低信号2例.在T2WI及PDWI像上12例均呈不均质高信号.5例可见靶征,7例可见神经出入征,4例可见脂肪分离征,2例同时出现以上3种征象.结论 四肢软组织神经鞘瘤的典型MRI征象是与神经走行一致的椭圆形肿块,T2WI呈不均质高信号,T1WI多呈稍高信号,边界清楚.靶征、神经出入征、脂肪分离征的存在有助于神经鞘瘤的诊断.     

MRI对四肢神经鞘瘤的诊断价值

目的:探讨四肢神经鞘瘤的MRI表现,提高MRI对四肢神经鞘瘤的诊断率.方法:回顾性分析23例经手术病理证实的四肢神经鞘瘤的MRI资料,其中上肢8例,下肢15例.23例均行常规MRI扫描,包括自旋回波(SE)T1WI,快速自旋回波(FSE)T2WI和SE T1WI增强扫描.结果:23例肿瘤有20例呈椭圆形或梭形,边界清楚光滑,14例位于神经血管束走行区,沿神经走行方向生长,并与神经偏心性相连,9例未追踪到起源神经.21例有完整包膜.绝大多数神经鞘瘤T1WI呈中等至低信号,所有肿瘤T2WI呈不均匀高信号或高低混合信号,增强扫描有不均匀强化.其中显示靶征6例,神经出入征14例,脂肪包绕征10例,脂肪尾征12例.结论:MRI有利于明确肿瘤的位置和范围,靶征、神经出入征、脂肪包绕征和脂肪尾征对诊断有重要价值.     

软组织神经鞘肿瘤的MRI诊断

目的 评价MR平扫及动态增强扫描对软组织神经鞘肿瘤的诊断价值。方法 回顾分析23例30个经病理证实软组织神经鞘肿瘤的MRI特征，其中15个良性神经鞘肿瘤，包括许旺瘤（神经鞘膜瘤）13个（12例），神经纤维瘤2个（2例）；15个为恶性外周神经鞘肿瘤。23例均行常规MR扫描，包括自旋回波（SE）T1WI，快速自旋回波（FSE）T2WI以及快速多平面扰相梯度回波序列（FMPSPGR）平扫和动态增强扫描。结果 （1）23例患者共30个病灶，软组织神经鞘肿瘤表现为梭形（15个），靶征（9个），神经出入征（10个），脂肪分离征（10个）；2个（2例）恶性神经鞘膜肿瘤显示周围水肿。（2）12个良性神经鞘肿瘤中9个表现为延迟强化，3个无明显强化或轻度强化；所有15个恶性外周神经鞘肿瘤及3个良性神经鞘肿瘤表现为第1期明显或中度强化，第2期和第3期持续强化或强化程度稍有下降。结论 梭形肿块、靶征、与神经关系密切及脂肪分离征是软组织神经鞘肿瘤较特征性的表现，而肿瘤的MR动态增强强化方式和周围有无水肿对神经鞘肿瘤良、恶性鉴别有一定价值。     

外周性神经源性肿瘤的MRI表现与病理基础研究

目的　分析外周性神经源性肿瘤的MRI表现。方法　对 2 5例神经源性肿瘤 (良性 19例 ,恶性 6例 )进行组织学观察 ,分析其与MR表现之间的关系及良恶性肿瘤的MRI鉴别诊断。结果　神经鞘瘤 14例 ,神经纤维瘤 5例 ,恶性周围性神经鞘瘤 (MP NST) 5例 ,原始神经外胚层瘤 1例。起源于神经干的肿瘤常呈纺锤形 ;肿瘤信号多欠均匀 ,T2 WI呈“靶征”者 3例 ,2例神经鞘瘤靶心有较多纤维组织 ,靶周明显水肿、粘液变性 ,1例MPNST靶心有较多纤维组织和部分钙化。 2例MPNST破坏骨质。结论　肿瘤的部位、形态和信号对诊断有较大帮助 ,恶性肿瘤可伴灶周水肿并可破坏邻近骨质。     

外周神经源性肿瘤的MRI表现与鉴别诊断

目的：探讨外周神经源性肿瘤的磁共振表现,旨在提高对该类疾病的影像学诊断水平。方法：回顾性分析经手术病理证实的外周神经源性肿瘤21例,其中神经纤维瘤14例,神经鞘瘤6例,恶性蝾螈瘤1例。所有神经源性肿瘤患者行 MRI 扫描。结果：4例神经纤维瘤表现为“葡萄藤”状,10例神经纤维瘤为分叶状,6例神经鞘瘤表现为梭形或类圆形肿块,恶性蝾螈瘤为团块状。神经纤维瘤 MR 均表现为 T1 WI 等信号,T2 WI 以高信号为主,其中夹杂低信号分隔;神经鞘瘤 T1 WI 呈稍低信号,T2 WI 表现为低信号周边环绕高信号即“靶征”;恶性蝾螈瘤在 T2 WI 上表现为高信号,其内可见环形或线样低信号分隔影。结论：外周神经源性肿瘤发生的部位、形状、大小以及信号特点均对其 MRI 诊断有帮助。     

椎管神经鞘瘤的MR表现及分型

目的:研究椎管神经鞘瘤的MR表现及分型。方法:对比60 例(66个肿瘤)椎管神经鞘瘤的MR表现与病理改变。结果:T1WI呈等或稍低信号、T2 信号高于脊髓、增强为均匀强化31 个肿瘤,病理证实为实质性肿瘤;T1 、T2WI整个信号强度与CSF相似、增强为环状强化13个肿瘤,病理为囊性肿瘤;T1、T2 信号强度不均匀、增强呈环状和肿块状强化21个肿瘤,病理为囊、实性肿瘤。结论:椎管神经鞘瘤的MR表现分为3型能客观地反映其病理特征,更有助于与很少囊变、多数表现为与脊髓呈等信号的脊膜瘤鉴别     

皮下良性神经鞘瘤的MRI表现(附5例报告)

目的:探讨皮下良性神经鞘瘤的MRI表现。方法:回顾性分析经手术病理证实的5例良性皮下神经鞘瘤的MRI表现。结果:肿瘤表现为皮下渐进性缓慢增大包块,活动度可,呈类圆形或梭形改变,边界清楚;病灶与神经主干或主要分支无关;T1WI表现为等低混杂信号,T2WI表现为等高混杂信号影,可见"靶征"2例,T2WI上见薄的高信号边缘1例。结论:MRI表现为皮下边界清晰高低混杂信号影、"靶征"或T2WI上薄的高信号边缘,以及临床表现有助于皮下良性神经鞘瘤的定性诊断。     

椎管内神经源肿瘤的低场MRI诊断

目的 :评价低场MRI对椎管内神经源肿瘤的诊断价值。材料和方法 :回顾性分析 2 6例经手术病理证实的椎管内神经源肿瘤 (神经鞘瘤 16例 ,神经纤维瘤 10例 )的低场MRI表现。结果 :2 6例中肿瘤呈圆形或卵圆形 17例、长条形 1例、哑铃状 8例。神经鞘瘤 16例中T1WI呈等信号 4例 ,略低信号 4例 ,等、略低信号 8例 ,T2WI呈不均匀高信号 ;增强扫描均匀增强 2例 ,不均匀增强 14例 ,其中多灶样不增强 6例。神经纤维瘤 10例中T1WI呈等信号 6例 ,略低信号 4例 ,T2WI呈较均匀高信号 ;增强扫描均呈均匀增强。结论 :低场MRI检查能诊断椎管内神经源肿瘤 ,并能鉴别神经鞘瘤和神经纤维瘤     

MRI对软组织肿瘤的鉴别诊断价值

目的:探讨软组织肿瘤的MRI表现及其组间鉴别诊断。方法:回顾性分析本院经手术病理证实的50例软组织肿瘤的病例资料,其中外周神经鞘瘤13例,侵蚀性纤维瘤10例,纤维肉瘤14例,恶性纤维组织细胞瘤7例,腺泡状软组织肉瘤6例。所有患者均行MR平扫,18例行MR增强扫描,其中2例行MR血管成像,2例行MR波谱成像。结果:50例软组织肿瘤中45例发生于四肢。纤维肉瘤与侵蚀性纤维瘤长径最长,约112.73mm与112.98mm,外周神经鞘瘤长径最短,约37.75mm。50例肿瘤边界均较清楚,T1WI呈等信号或稍高信号,T2WI呈高信号夹杂多发线样或片状低信号分隔。外周神经鞘瘤为类圆形软组织肿块,MRI特异征象为"靶征"、"神经出入征"及"脂肪彗星尾征"。侵蚀性纤维瘤T2WI呈高信号且有多发粗条状低信号分隔。纤维肉瘤主要表现为多发囊变坏死、出血及邻近组织受侵犯。恶性纤维组织细胞瘤多呈边界不清的分叶状,可见囊变坏死与出血灶,T2WI背景呈高信号。腺泡状软组织肉瘤多呈类圆形,病灶内可见血液流空信号及线样低信号分隔。结论:好发于四肢的T1WI呈等信号或稍高信号的软组织肿瘤极易混淆,但各种肿瘤的MRI表现有差异,再结合各自的临床特征,鉴别五种肿瘤并不困难。     

低场MRI对四肢软组织神经鞘肿瘤的诊断价值

目的:探讨四肢软组织神经鞘肿瘤的低场MRI诊断价值。方法:回顾性分析8例经临床病理证实的四肢神经鞘肿瘤的MRI表现,其中神经鞘瘤6例(5例良性,1例恶性),神经纤维瘤2例(良恶性各1例);下肢3例,上肢5例。结果:8例肿瘤均表现为梭形肿块,边界较清晰,6例良性神经鞘肿瘤中4例可见靶征,5例可见脂肪分离征,1例可见神经出入征;2例恶性肿瘤均未见靶征及神经出入征,其中1例可见脂肪分离征。Gd-DTPA增强扫描良性肿瘤均匀强化或实性结节均匀强化,恶性肿瘤强化不均匀。结论:四肢神经鞘肿瘤低场MRI表现有一定特征性,能为外科手术计划的制定提供很大的帮助。     

Differentiation of soft tissue benign and malignant peripheral nerve sheath tumors with magnetic resonance imaging

PURPOSE: The objective of this study was to differentiate the magnetic resonance (MR) imaging appearance of benign peripheral nerve sheath tumors (PNSTs) from that of malignant PNSTs. MATERIALS AND METHODS: Twenty-six patients who underwent MR imaging and had a histologic diagnosis of benign (schwannoma, n=16; neurofibroma, n=1) or malignant (n=9) PNST were retrospectively reviewed. The size, location, shape, margin, and signal intensities of the tumors on precontrast and gadolinium-enhanced MR imaging were analyzed. In each patient, the presence or absence of split fat, target, and fascicular signs was determined. RESULTS: The mean size of the benign PNSTs (3.4 cm, S.D.=2.5 cm) was significantly smaller than that of the malignant tumors (8.2 cm, S.D.=3.1 cm) (P<.001). Seventeen (65.4%) of the 26 tumors were spindle shaped or ovoid (12 benign and 5 malignant tumors). Contiguity with specific nerves was identified in 15 (88.2%) of the 17 benign PNSTs but in none of the malignant tumors (P<.05). Well-defined margins were noted in all 17 benign PNSTs but in only 3 (33.3%) of the 9 malignant tumors (P<.001). Five (55.6%) of the 9 malignant PNSTs but none of the benign tumors showed signal intensity change in adjacent soft tissue (P<.05). There was no significant difference in signal intensity between the benign and malignant tumors on T(1)-weighted, T(2)-weighted, and contrast-enhanced MR images. The split fat and target signs were present more frequently in the benign PNSTs than in the malignant PNSTs (P<.05).Conclusions: Benign and malignant PNSTs are often spindle shaped. Recognition of contiguity with adjacent nerves, a well-defined margin, and the presence of the split fat sign may suggest benignity. Imaging features suggestive of malignancy can be a larger size and an infiltrative margin.     

MR of benign peripheral nerve sheath tumors

Seventeen benign peripheral nerve sheath tumors were studied using MR. In all cases T2 relaxation time, signal intensity on T1-weighted images (lesion/muscle ratio), detectability of nerve of origin, nerve-lesion relationship, and presence of a capsule were assessed. Sixteen tumors showed marked hyperintensity on T2-weighted images with T2 relaxation times values greater than 95 ms. One schwannoma was almost isointense with fat (T2 60 ms). All lesions were isointense with muscle on T1-weighted images. In schwannomas the nerve was usually situated at the periphery of the lesion and only in one case was it obliterated by the mass. In neurofibromas the nerve was either visible in a central position within the mass (two cases) or no longer visible (five cases). A capsule could be detected in 70% of the schwannomas and in 30% of the neurofibromas. In patients with soft tissue masses, MR may contribute to recognition of nerve sheath tumors by showing the nerve of origin and typical signal hyperintensity on T2-weighted images. It can also be helpful in distinguishing between schwannomas and neurofibromas by the location of the nerve of origin and the presence of a capsule.     

MR imaging of extracranial nerve sheath tumors.

We retrospectively reviewed MR images of 32 histologically proven extracranial nerve sheath tumors (NSTs). There were 23 benign (10 neurofibromas, 13 schwannomas) and 9 malignant NSTs. On T1-weighted images (T1WIs) tumors were isointense or slightly hyperintense to muscle. On T2-weighted images (T2WIs) (11 lesions) and enhanced T1WIs (1 intraspinal lesion), a target pattern with peripheral hyperintense rim and central low intensity was seen in 12 of 23 (52%) benign NSTs (5 of 10 neurofibromas and 7 of 13 schwannomas). This pattern corresponded histologically to peripheral myxomatous tissue and central fibrocollagenous tissue. The pattern was absent in lesions with cystic, hemorrhagic, or necrotic degeneration. These tumors were hyperintense and variably inhomogenous on T2WIs. Malignant NSTs were hyperintense and variably inhomogenous on T2WIs and mimicked benign variably inhomogeneous lesions unless involvement of contiguous structures was visualized. A target pattern was not visible in malignant lesions. Magnetic resonance imaging cannot distinguish schwannomas from neurofibromas, and benign tumors may mimic malignant NSTs when cystic, hemorrhagic, and necrotic degeneration is present. A target pattern may be visualized in some benign NSTs, and evaluation of this sign with assessment of location and growth along nerves may help to avoid confusion with other lesions.     

磁共振信号强度在胸膜疾病中的诊断意义

目的评价磁共振信号强度在胸膜疾病中的诊断价值.方法48例不同胸膜疾病病人在Philips0.5T扫描仪下行MR检查.成像常规为T1WI、T2WI快速自旋回波扫描,所有病例均在病理证实结合临床资料下得出恶性或良性胸膜疾病的诊断.恶性疾病包括胸膜间皮瘤(n=10)、胸膜转移瘤(n=18),良性疾病包括结核性胸膜炎(n=9)、胸膜肥厚(n=7)、纤维胸(n=1)、脓胸(n=2)和胸膜炎性假瘤(n=1).将各种胸膜疾病T1WI、T2WI上绝对信号强度(ASI),病灶信号与肌肉信号的对比噪声比(CNR),信号强度比(SIR)分别进行测量或计算,判断它们在良、恶性胸膜疾病之间,胸膜间皮瘤与胸膜转移瘤之间是否存在差别.结果ASI在良、恶性胸膜疾病之间,胸膜间皮瘤与转移瘤之间均无显著差异,CNR在良、恶性胸膜疾病之间于T2WI上有差别(P＜0.01),而SIR在良、恶性胸膜疾病之间于T1WI、T2WI上均有极显著差异(P＜0.001),同时,还在胸膜间皮瘤与转移瘤之间于T2WI上存在差别(P＜0.05).结论磁共振信号强度在胸膜疾病鉴别诊断中有重要意义,其中SIR最具有诊断价值.MR信号强度在T2WI上比T1WI上更具有区分不同胸膜疾病的能力.     

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.     

软组织神经源性肿瘤的MRI诊断

目的：评价ＭＲＩ对软组织神经源性肿瘤的诊断价值。材料与方法：回顾分析１３例软组织神经源性肿瘤的ＭＲＩ表现,其中良性神经源性肿瘤１０例,恶性３例,均经手术病理证实。结果：大部分肿瘤表现为卵圆形或梭形（ｎ＝１１）,边缘清晰（ｎ＝１１）,与邻近神经血管束关系密切（ｎ＝１２）。Ｔ１ＷＩ上均匀或轻度不均匀（ｎ＝９）,均为等于或稍高于肌肉信号。Ｔ２ＷＩ上为中等或明显不均匀（ｎ＝１０）高信号,仅１例神经纤维瘤于     

Imaging tumours of the brachial plexus

Tumours of the brachial plexus are rare lesions and may be classified as benign or malignant. Within each of these groups, they are further subdivided into those that are neurogenic in origin (schwannoma, neurofibroma and malignant peripheral nerve sheath tumour) and those that are non-neurogenic. Careful pre-operative diagnosis and staging is essential to the successful management of these lesions. Benign neurogenic tumours are well characterized with pre-operative MRI, appearing as well-defined, oval soft-tissue masses, which are typically isointense on T1-weighted images and show the "target sign" on T2-weighted images. Differentiation between schwannoma and neurofibroma can often be made by assessing the relationship of the lesion to the nerve of origin. Many benign non-neurogenic tumours, such as lipoma and fibromatosis, are also well characterized by MRI. This article reviews the imaging features of brachial plexus tumours, with particular emphasis on the value of MRI in differential diagnosis.     

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.     

Simultaneous neurofibroma and schwannoma of the sciatic nerve.

The authors report a case of simultaneously occurring neurofibroma and schwannoma of the sciatic nerve and discuss the complementary aspects of MR and US. The schwannoma was well-defined and showed distal enhancement on sonographic evaluation, whereas the neurofibroma was ill-defined; both tumors were hypoechoic. T1- and T2-weighted MR images revealed similar signal characteristics of the two tumors, but intense enhancement following administration of gadolinium-DTPA distinguished the schwannoma from the neurofibroma.