颅底脊索瘤的MRI诊断

目的 研究颅底脊索瘤的MRI表现，探讨其MRI诊断价值。资料与方法 回顾性分析经手术病理证实的17例颅底脊索瘤的MRI表现，13例行CT检查。结果 颅底脊索瘤发生在斜坡11例(64．7％)，鞍区6例(35、3％)；肿瘤形态以类圆形分叶状为主(88％)；病变呈不均匀长T1、长T2信号，病灶内可见囊变、出血、钙化灶；病变侵犯邻近结构器官如：斜坡、垂体、海绵窦等；MRI增强扫描示病变呈持续性“蜂房样”不均匀强化10例，均匀强化2例。结论 MRI可清晰显示颅底部脊索瘤的部位、大小、范围、内部结构及与周围神经、血管的关系，具有较高的敏感性和一定特征性，有助于制定合适的手术方案和预后的估计。     

脊索瘤的MRI表现

目的：探讨脊索瘤的MRI表现及其诊断价值。方法：回顾性分析17例经临床病理证实的脊索瘤的MRI表现。结果：颅底脊索瘤8例，骶尾部脊索瘤9例，邻近颅底及椎体骨质均有溶骨性破坏，伴硬膜外及骶前较大软组织肿块。17例中16例信号不均匀，T1WI呈低、等信号，T2WI呈明显高信号，MRI增强扫描后，肿瘤均有轻度或中度不均匀性强化。结论：T2WI显著高信号是脊索瘤的特征性MRI表现，有重要鉴别诊断意义，MRI反映肿瘤的部位、侵犯范围以及显示骨质破坏作用均优于CT。     

脊索瘤MRI诊断

目的　了解脊索瘤的MRI表现特征。方法　分析 3 9例脊索瘤的MRI表现。结果　颅底部脊索瘤 16例 ,15例破坏颅底并有硬膜外软组织肿块 ,1例位于颅内右侧桥前池区 ,骨质无破坏。骶尾部脊索瘤 2 3例 ,椎体均有破坏 ,2 2例伴骶前较大软组织肿块。肿瘤边界清楚 ,T1WI呈低～等信号 ,T2 WI呈较高～高信号 ;3 6例信号不均匀 ,14例有条状低信号纤维间隔和高信号粘液基质。结论　MRI可清楚地显示肿瘤的部位和范围 ,根据肿瘤侵犯特点和信号特征 ,多数肿瘤可以定性诊断     

颅底脊索瘤的CT、MRI分析

目的:分析颅底脊索瘤的CT、MRI表现,探讨CT和MRI的诊断价值。方法:回顾性分析经手术病理证实的15例颅底脊索瘤,6例同时进行CT、MRI扫描,4例仅行CT扫描,5例仅行MRI扫描,2例同时行CTA检查。结果:颅底脊索瘤发生在斜坡8例,鞍区5例,颈静脉孔区1例,1例同时跨颅中、后窝生长。形态多为类圆形或不规则形,13例边界清晰,2例边界不清晰。CT表现肿块呈不均匀等或稍高密度软组织块,7例见斑点状钙化,8例见不同程度骨质破坏。MRI肿块信号不均匀,T1WI呈稍低信号或等信号,T2WI呈明显高信号,增强扫描呈不均匀轻中度强化。MRI扫描对病变范围的显示优于CT。结论:颅底脊索瘤有典型的好发部位,T2WI明显高信号较具特征性,CT和MRI对术前诊断颅底脊索瘤有较大价值。     

脊椎脊索瘤的MRI表现

目的了解脊椎脊索瘤的MRI表现特征。资料与方法分析33例脊椎脊索瘤的MRI表现。结果骶尾部24例,颈椎6例,胸椎2例．腰椎1例。脊椎脊索瘤表现为椎体骨质破坏,并轻度膨胀性改变,常伴椎体前方巨大软组织肿块。在骶骨正中矢状面上,其前方巨大球形肿块与骶骨常呈锐角相连。33例脊索瘤均呈长T1长T2信号,其内信号不均匀。增强扫描12例,11例呈不均匀强化,1例呈明显均匀强化。结论MRI可准确清楚地显示脊索瘤的部位、范围、形态、信号特点和增强表现,大多数脊索瘤可在术前做出正确的诊断。     

颅内脊索瘤的MRI表现及其临床意义

目的探讨颅内脊索瘤的MRI改变及其临床意义。材料与方法对1992年至2001年21例经手术和病理证实的颅内脊索瘤的MRI影像学表现进行了回顾性分析。结果颅内脊索瘤大多发生于颅底中线处的斜坡和／或鞍区,并广泛侵犯颅底的神经和大血管等重要结构;在T1WI主要表现为低信号,T2WI表现为不均匀高信号,Gd—DTPA静脉注射增强后,均有较明显的不均匀强化。此外,侵及斜坡的脊索瘤均出现斜坡形态和其内MR信号的异常改变。结论MRI检查颅内脊索瘤的临床意义在于明确肿瘤的部位、大小和范围,评价肿瘤对颅底神经和大血管等重要结构的侵犯情况,有助于和斜坡与鞍区的其它疾病如骨软骨瘤、颅咽管瘤的鉴别。从而制定合适的手术方案。     

MRI与CT在颅底脊索瘤诊断中的价值

目的：分析发生在颅底部脊索瘤的MRI和CT表现，以探讨MRI和CT在颅底部脊索瘤诊断中的价值。方法：搜集22例证实的病例，其中男性13例，女性9例，最大年龄67岁，最小年龄13岁，平均年龄42岁。22例均行MRI平扫和增强检查，其中7例进行了GT检查。结果：肿瘤发病部位主要位于斜坡及其周围区域，其中斜坡15例、鞍内2例、鞍旁1例、颈静脉孔区2例、蝶窦1例、鼻咽部1例。肿瘤的形态以不规则形最多16例，圆形4例，椭圆形2例。病灶边界清楚15例，边缘模糊7例。MRI表现T1WI呈低、等、高混杂信号，T2WI以高、低信号为主，其中18例呈混杂信号，4例表现为信号均匀。增强后病灶呈不均匀轻到中度强化，强化信号不均匀。CT病灶呈不均匀等或稍高密度肿块，均见不同程度的骨质破坏。结论：MRI由于有多轴面成像的优势，可以准确显示颅底脊索瘤的大小、形态、边界及其信号特点。CT在显示病灶的骨质破环、残存骨质方面较MRI具有优势。因此，MRI和CT相结合在颅底脊索瘤的诊断中具有很大的价值。     

颅底脊索瘤的CT和MRI影像诊断与鉴别诊断

目的探讨颅底脊索瘤CT与MR影像学诊断与鉴别诊断。方法回顾性分析13例经病理证实的颅底脊索瘤的CT与MR影像学资料。结果13例脊索瘤中,发生在斜坡5例,鞍区4例,颅中凹2例,鼻咽部1例,蝶窦1例。肿瘤的形态以不规则形最多8例,圆形3例,椭圆形2例。病灶边界清楚9例,边缘模糊4例。MR表现为T1WI呈低、等、高混杂信号,T2WI则以高、低混杂信号为主。增强后病灶呈轻到中度强化,强化信号不均匀。CT见病灶呈不均匀等或稍高密度肿块,7例可见不同程度的骨质破坏。结论颅底脊索瘤的CT和MR表现有一定的特征性,结合临床大多可以确诊,但需与脑膜瘤、垂体瘤、鼻咽癌、软骨类肿瘤等鉴别。     

垂体泌乳素瘤伽玛刀治疗后的MRI研究

目的 探讨伽玛刀治疗泌乳素瘤（PRL）的临床疗效及MRI的影像学变化。资料与方法 回顾性分析78例PRL伽玛刀治疗后的MRI随访影像资料,平均随访期32．5个月（12～96个月）,评价MRI在PRL伽玛刀治疗后影像学变化中的作用。结果 78例中肿瘤完全消失35例（占44．9％）,肿瘤体积缩小37例（占47．4％）,体积无变化6例（占7．7％）,肿瘤总控制率100％。2例肿瘤伽玛刀治疗后3和9个月出现一过性坏死肿胀。临床症状总改善率为73例（93．6％）,其中12个月以内改善率为62例（79．5％）。结论 伽玛刀治疗PRL能够很好地控制肿瘤生长和PRL过量分泌,这种作用随着随访时间延长具有放大效应。     

颅内脊索瘤与鼻咽癌的MRI诊断及鉴别诊断

目的探讨颅内脊索瘤和鼻咽癌的MRI诊断及鉴别诊断,评价MRI诊断价值。方法回顾性分析经病理证实的8例脊索瘤、23例鼻咽癌的MRI表现。结果7例脊索瘤中心部位在颅底中线处的斜坡/鞍区,肿瘤以颅底为主,主要向颅内蔓延,广泛破坏枕骨斜坡或蝶骨体,呈边界清楚、范围较大的骨质缺损;与鼻咽部生长为主再向颅内侵犯的鼻咽癌不同。颅内脊索瘤和鼻咽癌因血供不同,强化亦有较明显区别。结论MRI是诊断颅内脊索瘤和鼻咽癌的很有效的检查方法,具有重要的诊断和鉴别诊断价值。     

脑动静脉畸形伽玛刀治疗后的影像学改变

目的：总结脑动静脉畸形（ＡＶＭｓ）伽玛刀治疗后的影像学改变。材料和方法：收集１９９３年１０月至１９９６中１２月在本院作伽玛刀治疗的４４例脑ＡＶＭｓ患者。２３例采用ＣＴ检查,２１例采用ＭＲＩ检查。观察治疗后畸形血管巢（ｎｉｄｕｓ）容积、密度和信号强度变化以及周围脑组织密度和信号强度变化。结果：显示了脑ＡＶＭｓ缩小和闭塞、放射性脑水肿、放射性脑坏死和放射后自发性脑出血的ＣＴ和ＭＲＩ表现。结论：ＣＴ和ＭＲＩ能清楚地显示本病治疗后正常转归和并发症的影像学改变,对评估疗效及指导并发症的临床处理具有重要意义。     

肾上腺转移瘤的伽马刀治疗

目的探讨肾上腺转移瘤的伽马刀治疗效果。方法对20例肾上腺转移瘤病人,用伽马刀进行肾上腺转移瘤适形放射外科治疗,以50%~60%等剂量曲线包绕病灶,周边剂量3.5Gy~4.5Gy,隔日1次,共8~10次。结果除2例因全身多处转移伴全身衰竭未完成治疗外,18例患者完成治疗。5例患者治疗后有2例生存超过1年,1年生存率为40%(2/5)。治疗后超过6个月的12例患者中,10例生存;6个月生存率为83.3%(10/12)。随访患者平均生存时间10个月。伽马刀治疗后3个月后复查,根据B超和CT检查肾上腺转移瘤,88.9%(16/18)患者的转移瘤有不同程度的缩小。77.8%(14/18)患者原有的腰痛症状逐步减轻。结论肾上腺转移瘤对放射治疗敏感,伽马刀治疗肾上腺转移瘤是比较安全有效的姑息治疗,无严重并发症。     

伽玛刀治疗难治性癫痫的临床观察

目的探讨伽玛刀治疗症状性难治性癫痫的疗效。方法2003年1月—2007年1月,我院应用国产旋转式立体定向放射系统(伽玛刀)治疗经长期正规药物治疗不能控制的脑内有病灶的难治性癫痫20例。选择靶点:头颅MR I扫描确定病灶部位,并结合脑电图、脑电磁图、PET-CT等检查确定;适当扩展病灶外延1~2 mm作为治疗靶点,靶点周边剂量10~13 Gy,中心计量为20~26 Gy。疗效评估采用国际抗癫痫联盟提出的疗效标准。结果20例患者术后平均随访15个月(3~42个月)。满意3例;显著改善9例;良好5例;效差2例;无效1例。显效率为85%。治疗后症状即开始缓解,治疗后症状稳定平均时间为4.1个月(0~11个月);未出现并发症。结论伽玛刀治疗难治性癫痫能够显著控制癫痫的发生、提高生活质量,对病灶明确的症状性难治性癫痫是一种较为理想的治疗方法。     

肝癌伽玛刀治疗后磁共振表现

目的 评价MRI平扫和动态增强对肝癌伽玛刀治疗后表现和疗效随访的价值.方法 回顾性分析57例肝癌伽玛刀治疗后MRI表现,并与AFP结果进行对照.结果 肝癌伽玛刀治疗后平扫主要有4种表现:(1)T1WI稍低信号,T2WI稍高信号.(2) T1WI和T2WI均呈稍低信号.(3)T1WI稍高信号,T2WI等稍高混杂信号.(4)T1WI和T2WI均呈稍高信号.坏死病灶动态增强扫描表现为:(1)持续环形强化;(2)蜂窝状强化;(3)病灶本身无强化,周围肝组织斑片状强化.复发癌灶或新发癌灶在动态增强时早期强化,延迟期造影剂退出.小肝癌组(<5 cm)肿瘤完全坏死率93.5%,大肝癌组肿瘤(≥5 cm)完全坏死率81.8%.2组疗效比较差异无统计学意义(P＝0.244).结论 MRI平扫和动态增强评价伽玛刀的疗效可靠、准确,伽玛刀术后定期MRI随访具有重要意义.     

脑海绵状血管瘤:γ-刀治疗后的MRI表现

目的 分析脑海绵状血管瘤γ-刀治疗后的MRI表现,评价γ-刀治疗脑海绵状血管瘤的疗效。资料与方法 搜集脑海绵状血管瘤γ-刀治疗患者36例,MRI随访24个月,分析γ-刀治疗后病灶MRI征象及临床症状的演变。结 果36例患者γ-刀治疗后6个月,MR／示28例患者瘤周水肿增大,瘤体信号无明显变化,16例患者症状加重。γ-刀治疗后12个月MR／示7例瘤体缩小及其信号减低,25例瘤周水肿增大,16例症状减轻;γ-刀治疗后24个月MR／示19例瘤体缩小,26例瘤体信号减低,26例瘤周水肿缩小,其临床症状减轻。结论 MRI可以准确地显示脑海绵状血管瘤γ-刀治疗后脑部的病理演变及转归,与临床症状的演变基本一致。     

听神经瘤伽玛刀术后的影像学表现

目的：探讨伽玛刀治疗听神经瘤后的影像学表现。方法：回顾研究５８例行伽玛刀治疗后随访时间在１２～２６个月（中位数１８个月）的听神经瘤病人。结果：伽玛刀术后肿瘤内坏死无强化率为６２．５％，其中１６．１％复强化。术后脑积水的发生率为１４．３％，肿瘤平均直径＜２ｃｍ患者中无一发生术后脑积水。桥脑或／或小脑水肿的发生率为５．２％。卡方检验示术前肿瘤平均直径与术后脑积水有统计学意义（Ｐ＜０．０１），部分患者术后发生脑积水和／或肿瘤内坏死，两者经卡方检验有统计学意义（Ｐ＝０．０１）。结论：肿瘤内坏死无强化为术后特征性的影像学表现，术后并发症在影像上表现为脑积水及桥脑和／或小脑水肿。术后脑积水的发生率随术前肿瘤平均直径增大而升高，术后脑积水的发生可能与肿瘤内坏死有关     

弥散成像对肝癌伽玛刀疗效评价的初步研究

目的:通过弥散加权成像评价肝癌患者伽玛刀治疗效果,为临床早期评价疗效提供客观依据.方法:72例肝癌患者(原发肝癌62例,转移性肝癌10例)共77个癌灶,分别于治疗前、治疗后3天、治疗后3个月行MR检查,包括常规序列及DWI扫描.以治疗后体积变化分为有效组、稳定组、进展组.比较治疗前及治疗后3天肿瘤中心及边缘肝组织的ADC值变化.结果:有效组及稳定组肿瘤中心ADC值治疗前后存在统计学差异,进展组无明显统计学差异;肿瘤周边组织的ADC值在三组前后均有统计学差异;进展组治疗前ADC值明显高于有效组及稳定组.结论:ADC值能够反映肝癌伽玛刀治疗后肿瘤组织内部的病理变化,为早期疗效的判断提供量化指标.     

Utility of Intravoxel Incoherent Motion MR Imaging for Distinguishing Recurrent Metastatic Tumor from Treatment Effect following Gamma Knife Radiosurgery: Initial Experience

BACKGROUND AND PURPOSE:Intravoxel incoherent motion MR imaging can simultaneously measure the diffusion and perfusion characteristics of brain tumors. Our aim was to determine the utility of intravoxel incoherent motion–derived perfusion and diffusion parameters for assessing the treatment response of metastatic brain tumor following gamma knife radiosurgery.MATERIALS AND METHODS:Ninety-one consecutive patients with metastatic brain tumor treated with gamma knife radiosurgery were assessed by using intravoxel incoherent motion imaging. Two readers independently calculated the 90th percentile and the 10th percentile histogram cutoffs for perfusion, normalized CBV, diffusion, and ADC. Areas under the receiver operating characteristic curve and interreader agreement were assessed.RESULTS:With the combination of the 90th percentile histogram cutoff for perfusion and the 10th percentile histogram cutoff for diffusion, the sensitivity and specificity for differentiating recurrent tumor and treatment were 79.5% and 92.3% for reader 1 and 84.6% and 94.2% for reader 2, respectively. With the combination of the 90th percentile histogram cutoff for normalized CBV and the 10th percentile histogram cutoff for ADC, the sensitivity and specificity for differentiating recurrent tumor and treatment were 69.2% and 100.0% for reader 1 and 74.3% and 100.0% for reader 2, respectively. Compared with the combination of 90th percentile histogram cutoff for normalized CBV and the 10th percentile histogram cutoff for ADC, adding intravoxel incoherent motion to 90th percentile histogram cutoff for normalized CBV substantially improved the diagnostic accuracy for differentiating recurrent tumor and treatment from 86.8% to 92.3% for reader 1 and from 89.0% to 93.4% for reader 2, respectively. The intraclass correlation coefficients between readers were higher for perfusion parameters (intraclass correlation coefficient range, 0.84–0.89) than for diffusion parameters (intraclass correlation coefficient range, 0.68–0.79).CONCLUSIONS:Following gamma knife radiosurgery, intravoxel incoherent motion MR imaging can be used as a noninvasive imaging biomarker for differentiating recurrent tumor from treatment effect in patients with metastatic brain tumor.

Perfusion MR imaging techniques have significantly advanced and can now provide information regarding tumor physiology. There are several reports suggesting the usefulness of dynamic susceptibility contrast-enhanced perfusion MR imaging for differentiating recurrent metastatic brain tumor from stereotactic radiosurgery–induced radiation necrosis.^1–3 However, quantitative brain perfusion measurement remains a challenge for currently available MR perfusion methods. DSC and dynamic contrast-enhanced MR imaging are inhibited by their signal nonlinearity, and arterial spin-labeling exhibits, in addition to a low signal-to-noise ratio, a strong dependence on the transit time.Le Bihan et al⁴ defined intravoxel incoherent motion (IVIM) as the microscopic translational motion occurring in each image voxel in MR imaging. In biologic tissue, this incoherent motion includes molecular diffusion of water and microcirculation of blood in the capillary network, referred to as “perfusion.” These 2 phenomena account for the biexponential decay of the signal intensity on DWI when different diffusion b-values are applied. With the IVIM theory, both true molecular diffusion and water molecule motion in the capillary network can be estimated by using a single diffusion imaging-acquisition technique. As opposed to DSC, dynamic contrast-enhanced imaging, and arterial spin-labeling, IVIM has a unique capillary dependence that is not sensitive to the coherent laminar flow of arteries and veins. The measurement of IVIM is intrinsically local (ie, the encoding and readout are performed at the same location).⁵In our clinical experience, the major advantage of IVIM MR imaging is that because it allows the simultaneous acquisition of diffusion and perfusion parameters, it can provide both measures within corresponding solid lesions without the requirement for a further coregistration processing step. In the current study, we attempted to validate the IVIM-derived perfusion and diffusion parameters by using the clinicoradiologic correlation in patients with post-gamma knife radiosurgery (GKRS) metastatic brain tumor. We also assessed the diagnostic accuracy and added value of the IVIM method for differentiating recurrent tumor from treatment effect, compared with the combination of DSC perfusion MR imaging and DWI, which has commonly been used as a parameter for brain tumor imaging.Our hypothesis was that the difference in vascularity between recurrent tumor and the treatment effect can be assessed by using an IVIM-derived perfusion fraction (f); and the combination of f and the true diffusion parameter (D) would show diagnostic performance comparable with the combination of normalized CBV (nCBV) and the ADC. The purpose of this study was to determine the utility of IVIM-derived perfusion and diffusion parameters for assessing the treatment response of metastatic brain tumor following GKRS.