颅内肉芽肿MRI分析

目的 探讨颅内肉芽肿的MRI特点.方法 回顾性分析11例经临床或手术病理证实的颅内肉芽肿的临床和MRI资料,重点分析MRI表现.结果 11例患者,7例为单发病灶,4例为多发病灶,共25个病灶,其中20个位于皮层及皮层下区.平扫检查,呈不规则片状13个、结节状11个、环状1个;20个边界清晰,5个边界欠清;25个周边均见水肿带,22个水肿明显.增强检查均明显强化,呈环状13个、结节状12个.T1WI呈高信号2个、等信号5个、低信号11个、高低混杂信号7个;T2WI呈高/稍高信号12个、等信号3个、低信号3个、高低混杂信号7个.DWI,12个结节状强化病灶中呈高/稍高信号8个、等信号2个、低信号1个、高低混杂信号1个;13个环状强化病灶,其中壁呈高信号9个、等信号1个、低信号3个,平均ADC值12.28×10-4 mm2/s;病灶中心呈高信号5个、等信号1个、低信号6个、高低混杂信号1个,平均ADC值6.94×10-4 mm2/s.1例行波谱检查,可见Glx峰明显增高,NAA峰降低,Cho峰无增高.结论 颅内肉芽肿MRI表现具有一定的特征,结合临床资料多可做出明确诊断.     

颅内少见部位胆脂瘤的MRI诊断

目的 探讨颅内少见部位胆脂瘤的MRI表现特征.提高该病的术前诊断率,减少误诊率.方法 回顾性分析经手术病理证实的6例颅内胆脂瘤的MRI表现,采用Siemens 3.0 T Skyra磁共振仪,均行平扫及增强扫描,1例加扫磁敏感加权成像(SWI)序列.结果 本组病例均为单发,枕大孔区1例,左侧中颅窝2例,右侧中颅窝1例,左侧枕叶脑实质2例.病灶范围较大,周边分叶状,灶周未见水肿,部分病灶沿阻力小的地方生长明显.5例T1WI、T2WI、T2 FLAIR序列信号混杂,DWI序列以高信号为主的混杂信号,其中枕大孔区病例信号较为特殊,T1 WI呈高信号,T2WI、T2FLAIR序列呈低信号,DWI为低信号,SWI序列最大强度投影(MIP)为稍高信号,相位(PHASE)图为等信号.结论 颅内少见部位胆脂瘤MRI表现具有特征性,可以做到术前定性诊断.     

鼻道、鼻咽恶性黑色素瘤的MRI诊断

目的 分析鼻道、鼻咽恶性黑色素瘤的MRI表现,探讨其诊断要点.方法 回顾性分析经病理证实的8例鼻道、鼻咽恶性黑色素瘤的MRI特征及临床资料,所有患者均行MR平扫、增强及动态增强检查.结果 肿瘤位于中鼻道1例,鼻咽部2例,鼻腔、上颌窦及同侧筛窦5例.5例可见明显骨质破坏并侵犯邻近结构,累及翼腭窝3例、颞下窝2例、眼眶4例、前颅底2例、咽旁间隙1例.MRI表现:3例直径＜2 cm,呈类圆形肿块,T1WI为高信号,T2 WI为低信号,呈明显均匀强化.5例直径＞3 cm,不规则肿块,MRI表现为混杂信号,T1WI以等、低信号为主,其内有斑片状高信号;在T2WI,1例以等低、信号为主,4例以稍高信号为主,增强扫描呈轻度不均匀强化.动态增强扫描时间-信号强度曲线平台型、流出型各4例.结论 鼻道、鼻咽恶性黑色素瘤MRI信号特征与肿瘤大小相关.肿瘤较小时T1WI呈高信号,T2WI呈低信号;肿瘤较大时MRI信号混杂,轻度不均匀强化为其特征.     

颅内孤立性纤维瘤的CT和MRI表现

目的分析颅内孤立性纤维瘤的CT和MRI表现,提高对其认识。资料与方法回顾性分析5例经手术病理证实的颅内孤立性纤维瘤的CT和MRI表现。1例行CT增强扫描,3例行MRI平扫和增强扫描,1例同时行CT和MRI扫描。结果 5例颅内孤立性纤维瘤均为单发,肿块形态不规则,边界清楚,直径1.2～6.5 cm。发生于颞叶1例,鞍内1例,桥小脑角区1例,中后颅窝三叉神经走行区1例,顶叶1例。CT平扫病灶均为高密度,增强扫描均匀强化。MR T1WI上3例病灶为等信号;1例为多发分隔囊状低信号。T2WI上3例病灶表现为等、低混杂信号,病灶内见少量斑片状高信号;1例为多发分隔囊状高信号。MRI增强所有病灶实质部分显著强化,T2WI低信号区明显强化,坏死囊变区未见强化。结论颅内孤立性纤维瘤MRI表现有一定的特点,MR T2WI上低信号、增强扫描呈显著强化较具特征。     

长骨纤维结构不良的MRI诊断

目的 探讨长骨纤维结构不良的MRI表现特点.方法 回顾分析16例经手术病理证实的长骨纤维结构不良患者的MRI影像资料.结果 与周围正常肌肉信号相比,病变在T1WI表现为均匀等信号4例,等信号为主的等、低混杂信号8例,均匀低信号3例;T2WI显示较均匀高信号3例,不均匀中等信号5例,中等信号为主的等、高混杂信号7例;1例在T1WI及T2WI均显示为均匀低信号.4例可见病灶内线样分隔,分隔在T1WI、T2WI均表现为低信号.注射Gd-DTPA增强扫描,病灶可表现为边缘强化、斑片状强化或不均匀强化.结论 纤维结构不良的MRI表现与病灶内不同病理组织成分相关,且MRI能够提供更全面的影像学信息.     

39例腹壁子宫内膜异位症的MRI表现

目的:探讨腹壁子宫内膜异位症的MRI征象及临床特点,探讨MRI的诊断价值.方法:本院39例经病理组织学证实的腹壁子宫内膜异位症患者,经盆腔MRI平扫及增强扫描,回顾性分析其影像表现及临床病理资料.结果:39例腹壁子宫内膜异位症中,大多数患者有剖宫产手术史,仅1例无腹部手术史.34例(87.2％)病灶边界模糊.22例(56.4％)病灶呈实性,T1WI呈等信号,T2WI呈混杂信号为主;15例(38.5％)病灶呈囊实性,T2WI呈高低混杂信号,T1WI以等低信号为主,其中抑脂T1WI中有高信号灶为7例;2例(5.1％)病灶呈囊性,T2WI及T1WI均呈高信号.囊性病灶增强扫描后强化不明显;实性及囊实性病灶增强扫描后病灶均可见持续性强化,病灶显示更加清晰.结论:结合临床病史及MRI表现特点,能准确诊断腹壁子宫内膜异位症,MRI能准确显示病灶位置、边界、大小及范围,对于临床治疗方案的制定有很大参考价值.     

肝脏孤立性坏死结节的MRI表现

目的 探讨肝脏孤立性坏死结节(solitary necrotic nodule ,SNN)的MRI表现.方法 分析经手术病理证实的SNN 20例的MRI表现.结果 依据其在MRI的T1WI和T2WI信号高低及增强后的表现分为4类:(1) 4个病灶在T1WI和T2WI均表现为低信号,其中2个病灶在T2WI上其内可见点状高信号,增强后无强化;(2)7个病灶在T1WI低信号,T2WI稍高信号,增强后无强化;(3)4个病灶在T1WI低信号,T2WI呈稍高信号,增强后门脉及延迟期边缘强化;(4)5个病灶在T1WI低信号,T2WI呈稍高信号伴中央点状或片状更高信号,增强后边缘强化.结论 平扫加动态增强MRI能较好反映SNN的影像学特点,提高了SNN的诊断准确率.     

多发原发性中枢神经系统淋巴瘤MRI诊断

目的 探讨多发原发性中枢神经系统淋巴瘤(MPCNSLs)的MRI特征及鉴别诊断要点.方法 回顾性分析7例经病理证实的MPCNSLs的MRI表现,其中男4例,女3例,平均年龄44岁.结果 7例共21个病灶(每例发现2～5个病灶),病灶平均大小为(2.99±1.25) cm;T1WI上几乎均呈低信号(20个病灶);T2WI上表现为高信号或混杂等高信号;液体衰减反转恢复序列上表现为高、等信号;增强扫描仅有1例(1个病灶)无强化,其余均可见不同程度及不同方式强化.结论 MPCNSLs常规MRI平扫与增强影像表现有一定的特征性,结合脑内多发特点可以做出较准确的诊断,为临床治疗提供帮助.     

结节性硬化症的MR诊断

目的探讨TS的MR影像特征.材料和方法本组17例.采用MR T1WI横断面、矢状面及T2WI横断面扫描.结果室管膜下结节17例,共119个结节,主要分布于侧脑室前角、体部及三角区外侧壁上,T1WI以等信号、高信号为主(91/119),T2WI以混杂高信号最多见.皮质结节12例,共120个结节,主要分布于额叶、顶叶(93/120).白质病灶8例,病灶呈放射带状、楔形及非特异性病灶,T1WI呈等低信号,T2WI呈高信号.室管膜下巨细胞星形细胞瘤3例,均位于室间孔区,T1WI呈等低信号,T2WI呈混杂高信号,增强后明显均匀强化.结论MRI是结节性硬化症最好的检查方法之一,其MR影像表现具有特征性.     

肾上腺髓性脂肪瘤的MRI诊断(附13例报告并与手术对照)

目的　探讨肾上腺髓性脂肪瘤的MRI表现特征及病理基础。方法　对 13例手术证实的肾上腺髓性脂肪瘤的MRI表现进行回顾分析 ,并与手术病理对照。结果　 13例术前均正确诊断 ,11例表现为肾上腺区巨大T1WI大部高信号伴不等量的团块状、条索状低信号占位 ,镜下高信号为成熟脂肪组织 ,低信号为骨髓组织。 2例T1WI表现为以等信号为主的高、等、低混杂信号 ,病理证实为肿瘤伴出血。T2 WI或T1WI抑脂后原高信号为略高于皮下脂肪的低信号 ,低信号骨髓组织及出血为明显高信号。全组病例增强后均无强化 ,2例伴出血感染者可见部分包膜强化。 13例均伴有下腔静脉前内移位。结论　高脂肪信号变化特征及增强后无强化为本病特征 ,MRI可在术前对本病作出正确诊断。     

Dynamic contrast-enhanced T2*-weighted MR imaging of tumefactive demyelinating lesions.

PURPOSE: Dynamic contrast-enhanced T2*-weighted MR imaging has been helpful in characterizing intracranial mass lesions by providing information on vascularity. Tumefactive demyelinating lesions (TDLs) can mimic intracranial neoplasms on conventional MR images, can be difficult to diagnose, and often result in surgical biopsy for suspected tumor. The purpose of this study was to determine whether dynamic contrast-enhanced T2*-weighted MR imaging can be used to distinguish between TDLs and intracranial neoplasms that share common features on conventional MR images. METHODS: We retrospectively reviewed the conventional and dynamic contrast-enhanced T2*-weighted MR images and medical records of 10 patients with tumefactive demyelinating disease that was diagnosed by either biopsy or strong clinical suspicion supported by laboratory evaluation that included CSF analysis and evoked potential tests. Twelve TDLs in 10 patients and 11 brain tumors that appeared similar on conventional MR images were studied. Relative cerebral blood volume (rCBV) was calculated from dynamic MR data and was expressed as a ratio to contralateral normal white matter. rCBV values from 11 patients with intracranial neoplasms with very similar conventional MR imaging features were used for comparison. RESULTS: The rCBV values of TDLs ranged from 0.22 to 1.79 (n = 12), with a mean of 0.88 +/- 0.46 (SD). The rCBV values of intracranial neoplasms ranged from 1.55 to 19.20 (n = 11), with a mean of 6.47 +/- 6.52. The difference in rCBV values between the two groups was statistically significant (P =.009). The difference in rCBV values between TDLs and primary cerebral lymphomas (n = 4) was less pronounced but was statistically significant (P =.005). CONCLUSION: Dynamic contrast-enhanced T2*-weighted MR imaging is a useful diagnostic tool in differentiating TDLs from intracranial neoplasms and may therefore obviate unnecessary surgical biopsy.     

Efficacy evaluation of gadoteridol for MR angiography of intracranial vascular lesions

A phase III multicenter study was conducted in 89 patients with known intracranial vascular lesions to evaluate an extracellular gadolinium contrast agent, gadoteridol, for intracranial magnetic resonance (MR) angiography. The pre- and postcontrast MR angiograms of 82 patients were evaluated by the unblinded investigators and by two blinded readers (A and B) for visualization of lesions; arterial and venous anatomy; extent, size, and number of lesions; and disease classification. The unblinded readers indicated that lesions were visualized better on postcontrast images in the following categories: venous anatomy, 87 (81%) of 107 lesions; arterial anatomy, 43 lesions (40%); and extent or size of lesions, 38 lesions (36%). In 29 (35%) of 82 patients, the unblinded readers determined that enhanced MR angiography provided more diagnostic information than unenhanced MR angiography. The blinded readers determined that enhanced MR angiography provided more information for visualization of vascular anatomy in more than 60% of cases. The additional information provided with gadoteridol would have changed the diagnosis in nine (8%) of 107 lesions seen by the unblinded readers, 11 (12%) of 90 lesions seen by reader A, and three (3%) of 93 lesions seen by reader B. The results confirm that the use of gadoteridol improves the visualization of intracranial vascular lesions with MR angiography. The authors conclude that development of new postprocessing algorithms will improve the utility of contrast-enhanced MR angiography.     

MR增强后液体衰减反转恢复序列对脑转移瘤的诊断价值

目的 分析MR增强后液体衰减反转恢复(fluid attenuated inversion recovery,FLAIR)序列对脑转移瘤的诊断价值. 资料与方法 确诊恶性肿瘤可疑有脑转移患者159例.MR检查除常规平扫和增强外,在增强后加扫FLAIR序列,图像由3名有经验的放射科医师评估. 结果 58例有脑内转移,6例增强后FLAIR脑实质病灶数目显示较增强T1WI多,11例病灶强化较T1WI明显;在11例柔脑膜转移者中,7例病灶强化程度优于增强后T1WI. 结论 增强后FLAIR是增强后T1WI的有效补充,对脑内小病灶和脑膜病灶更敏感.     

Clinical experience with routine Gd-DTPA administration for MR imaging of the brain

A retrospective analysis of intracranial magnetic resonance (MR scans of 514 patients who underwent nonselective Gd-DTPA enhanced MR imaging was performed to determine the efficacy of this protocol for Gd-DTPA administration. This report reviews the frequency and clinical significance of abnormally enhancing areas that were entirely undetectable on precontrast images or would have been missed without the retrospective knowledge of enhancement. Fifty-seven patients (11% of the 514 patients studied) showed enhancing lesions, with 16 (3.1% of the total) of these patients demonstrating one or more lesions identifiable only on postcontrast images. Of those 16 patients, 8 had other focal abnormalities on precontrast studies, whereas the remaining 8 (1.6% of the total) had negative precontrast studies. The new diagnoses affected clinical management directly in five patients and in another nine contributed potentially significant information. Considerations regarding a selective versus nonselective protocol for Gd-DTPA administration for intracranial MR imaging and the use of clinical information to augment these protocols are discussed.     

Positron emission tomography compared with magnetic resonance imaging and computed tomography in supratentorial gliomas using multiple stereotactic biopsies as reference

Ten patients with findings at computed tomography (CT) suggesting intracranial supratentorial glioma were investigated to compare the diagnostic efficacy of this technique with that of positron emission tomography (PET) using 11C-methionine and examinations with magnetic resonance (MR). The findings were related to histopathologic examination of serial stereotactic biopsies, which were guided by the appearance of the lesions on PET examination. To obtain corresponding slice orientation with the different examination techniques, an individually shaped helmet fixation was used. However, in 3 cases this fixation device could not be used for MR. Histopathologic diagnosis, obtained in all cases from multiple target stereotactic biopsies, included glioma in 9 patients and reactive gliosis in one case. A detailed comparison of the three imaging techniques and the findings at stereotactic biopsies was possible in 7 patients, while in 3 patients comparison with MR was less exact due to the patient's refusal to wear the helmet during this examination. MR was the most accurate method for outlining the total extent of a lesion, i.e. the tumor and the edema surrounding it. Four lesions had homogeneous signal characteristics and in 6 lesions two (or more) compartments could be distinguished with MR. In 5 cases the MR findings were in complete agreement with the histopathologic findings. However, a thorough correlation between signal characteristics and histology was not possible. Using PET the occurrence and the extent of tumor tissue was correctly predicted in 7 patients. The PET was normal in one case. Findings at CT were in agreement with the histopathologic diagnosis in 5 patients. MR was the most sensitive method for the detection of lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gd-DTPA-enhanced MR imaging of leptomeningeal spread of primary intracranial CNS tumor in children

Three children with known primary brain neoplasms and leptomeningeal disease were evaluated with MR imaging. Two of the patients had medulloblastoma and one had pineoblastoma. The presence of leptomeningeal tumor spread was established by positive CSF cytopathology in conjunction with compatible contrast-enhanced CT findings. Contrast-enhanced CT, nonenhanced MR, and Gd-DTPA-enhanced MR studies were then compared. In two cases, leptomeningeal lesions were seen better with Gd-DTPA-enhanced MR than with contrast-enhanced CT. In all three cases, Gd-DTPA MR imaging revealed lesions that were not identified on noncontrast MR. Gd-DTPA-enhanced MR imaging is useful when searching for intracranial leptomeningeal tumor deposits in pediatric patients at risk for this condition.     

MR imaging detection of calcified intracranial lesions and differentiation from iron-laden lesions.

Magnetic susceptibility variation caused by calcium permits limited detection of intracranial calcifications and/or their distinction from iron-laden lesions with spin-echo or gradient-echo magnetic resonance (MR) techniques. The magnetic susceptibility sensitivity of phase imaging has been used to detect iron-laden lesions. A new approach that combines the magnetic susceptibility sensitivity of both gradient-echo and phase imaging to yield greater imaging sensitivity to calcium is presented. Two-dimensional fast low-angle shot (FLASH) gradient-echo imaging with phase image reconstruction (gradient-echo phase [GEP]) was used at 1.0 and 1.5 T. Twelve patients with computed tomography-proved calcified intracranial lesions (greater than or equal to 200 HU) and seven patients with iron-laden intracranial lesions having a characteristic appearance on T1- and T2-weighted and FLASH MR images were studied. The GEP imaging technique helped detect calcified intracranial lesions (greater than or equal to 200 HU) and helped distinguish them from iron-laden lesions.     

脑血管畸形的MRI及MRA诊断

目的：研究脑动静脉畸形与海绵状血管瘤的ＭＲＩ及ＭＲＡ特征，评价不同的成像方法对脑血管畸形的诊断价值。材料与方法：对２１例脑动静脉畸形及６例海绵状血管瘤分别作了常规ＭＲ成像及ＭＲ血管成像，ＭＲＩ采用ＳＥＴ１和Ｔｕｒｂｏ ＳＥ Ｔ２加权序列，ＭＲＡ采用２Ｄ－ＦＬＡＳＨ及３Ｄ－ＦＩＳＰ序列，６例海绵状血管瘤ＭＲＡ仅使用２Ｄ－ＦＬＡＳＨ序列。所有成像以环形激化头线圈在１．０Ｔ ＭＲ仪上完成。结果：Ｔ１及Ｔ     

三维增强磁共振静脉成像评价颅内静脉系统

目的:比较三维增强FLASH序列和2D TOF序列MR静脉成像(MRV)对颅内静脉系统的诊断价值.方法:本组11例中健康志愿者6例(正常组),脑静脉窦血栓形成患者5例(病变组),均同时行3D增强FLASH和2D TOF序列MRV扫描,病变组5例患者同时行DSA检查.将脑内主要静脉(14支)的显示情况分为3级:满意显示,一般显示和未显示.比较两种扫描方法对脑内静脉和静脉血栓的显示情况.结果:正常组中三维增强FLASH和2D TOF序列对所观察的14支脑静脉的满意显示率、一般显示率和未显示率分别为88.10%,5.95%,5.95%和30.95%,53.57%,15.48%.三维增强FLASH未显示结构主要为下矢状窦.病变组5例中DSA共发现12处血管病变,三维增强FLASH显示优于2D TOF 10处,两者相仿2处.结论:三维增强FLASH对脑静脉系统的显示优于2D TOF序列,可以提供高质量的脑内静脉结构的图像,对诊断脑静脉内血栓形成有重要临床价值.     

磁共振扩散加权成像对于颅内表皮样囊肿的诊断价值

目的:探讨磁共振扩散加权成像(DWI)对于颅内表皮样囊肿的诊断价值。方法:回顾性分析11例经手术病理证实的颅内表皮样囊肿术前常规MRI和DWI的信号特征。结果:11例均为单发;7例表现为囊状均匀性长T1长T2信号,4例病灶信号不均匀,以长T1长T2信号为主,其内混杂少许等T1等T2信号;5例行增强扫描均未见异常强化;所有病灶在DWI上均表现为明显高信号,边界清楚,ADC图表现为中等信号。结论:DWI对于颅内表皮样囊肿的诊断及鉴别诊断具有重要价值,应作为首选检查与常规扫描同时应用。