Cord Dose Specification and Validation for Stereotactic Body Radiosurgery of Spine

Effective dose to a portion of the spinal cord in treatment segment, rather than the maximum point dose in the cord surface, was set as the dose limit in stereotactic-body radiosurgery (SBRS) of spine. Such a cord dose specification is sensitive to the volume size and position errors. Thus, we used stereotactic image guidance to minimize phantom positioning errors and compared the results of a 0.6-cm³ Farmer ionization chamber and a 0.01-cm³ compact ionization chamber to determine the detector size effect on 9 SBRS cases. The experimental errors ranging from 2% to 7% were estimated by the deviation of the mean dose in plans to the chamber with spatial displacements of 0.5 mm. The mean and measured doses for the large chamber to individual cases were significantly (17%) higher than the doses with the compact chamber placed at the same point. Our experimental results shown that the mean doses to the volume of interest could represent the measured cord doses. For the 9 patients, the mean doses to 10% of the cord were about 10 Gy, while the maximum cord doses varied from 11.6 to 17.6 Gy. The mean dose, possibly correlated with the cord complication, provided us an alternative and reliable cord dose specification in SBRS of spine.     

Stereotactic Image-Guided Intensity Modulated Radiotherapy Using the HI-ART II Helical Tomotherapy System

The highly integrated adaptive radiation therapy (HI-ART II) helical tomotherapy unit is a new radiotherapy machine designed to achieve highly precise and accurate treatments at all body sites. The precision and accuracy of the HI-ART II is similar to that provided by stereotactic radiosurgery systems, hence the historical distinction between external beam radiotherapy and stereotactic procedures based on differing precision requirements is removed for this device. The objectives of this work are: (1) to describe stereotactic helical tomotherapy processes (SRS, SBRT); (2) to show that the precision and accuracy of the HI-ART meet the requirements defined for SRS and SBRT; and (3) to describe the clinical implementation of a stereotactic image-guided intensity modulated radiation therapy (IG-IMRT) system that incorporates optical motion management.     

Early Clinical Experience With Kilovoltage Image-Guided Radiation Therapy for Interfraction Motion Management

Interest in image-guided radiation therapy (IGRT) reflects the desire to minimize interfraction positioning variability. Using a kilovoltage (kV) imaging unit mounted to a traditional LINAC allows daily matching of kV images to planning digitally reconstructed radiographs (DRRs). We quantify and evaluate the significance of calculated deviation from the intended isocenter. Since September 2004, 117 patients with various malignancies were treated using the On-Board Imaging (OBI) system, with 2088 treatment sessions. Patients were positioned by the treating therapist; orthogonal images were then obtained with the OBI unit. Couch shifts were made, aligning bony anatomy to the initial simulation image. Routine port films were performed weekly (after that day's OBI session). Ninety percent of all lateral, longitudinal, and vertical shifts were less than 0.8 cm, 0.6 cm, and 0.7 cm, respectively. The median vector shift for each anatomic site was: 0.42 cm for head and neck, 0.40 cm for CNS, 0.59 cm for GU/prostate, and 0.73 cm for breast; shift magnitude did not change with successive OBI sessions. The use of OBI effectively corrects setup variability. These shifts are typically small and random. The use of OBI likely can replace weekly port films for isocenter verification; however, OBI does not provide field shape verification.     

皮层体感诱发电位在脊柱脊髓疾患中的临床应用

目的 了解皮层体感诱发电位在脊柱脊髓疾患诊治中的临床应用价值方法 120例患者用Frankel分级判断脊髓功能，行皮层体感诱发电位术前检查、术中监护以及术后疗效评估，并分析应有和不同标准的监测结果 。结果 （1）皮层体感诱发电位Ⅰ型表现者全部为FrankeA级；Ⅱ型主要为B、C级；Ⅲ型主要为C、D级；Ⅳ型主要为D、E级。（2）Ⅰ－Ⅳ型皮层体感诱发电位表现者临床疗效分别为0、54．2％、82．8％、84．2％。（3）行椎体肿瘤切除、椎管内肿瘤切除、脊柱侧凸凹侧撑开及颈椎后路“单开门”时最易引发皮层体感诱发电位变化。（4）应用不同标准行术中监测灵敏度均为100％，特异度分别为85．6％、93．3％，误诊率分别为14．4％、6．7％，漏诊率均为0。结论 皮层体感诱发电位与Frankel分级、临床疗效有良好的相关性；皮层体感诱发电位灵敏度高，可及时反映出脊髓功能的变化，提高了脊髓手术的安全性；皮层体感诱发电位术中监测标准具有一定弹性，常因病情、部位及操作不同而变化。     

脊髓血管畸形的临床特征与影像学分类的相关性研究

目的：分析研究脊髓血管畸形的临床特征与影像学分类的相关关系。材料和方法：收集了６２例经ＭＲＩ、ＤＳＡ和（或）手术病理证实的髓血管畸形患者,其中髓内隐匿型动静脉畸形（ＡＶＭｓ）１３例、球形ＡＶＭｓ５例、幼稚型ＡＶＭｓ１２例：髓周膜内动静脉瘘（ＡＶＦ）Ⅰ型５例、Ⅱ型１２例、Ⅲ型７例;硬膜型ＡＶＦ８例。结果：脊髓ＡＶＭｓ中,隐匿型ＡＶＭｓ无明显的性别差异,余各类型男性均多于女性;髓内ＡＶＭｓ、髓周ＡＶＦ以青少年多见,硬膜型ＡＶＦ发生于中老年;髓内ＡＶＭｓ多见于颈髓及胸腰段脊髓,髓周ＡＶＦ及硬膜型ＡＶＦ多见于胸腰段;髓内ＡＶＭｓ以急性起病多见,髓周ＡＶＦ表现为进行性加重,少数可急性发作,硬膜型ＡＶＦ以慢性起病多见;髓内出血者预后较无出血者差。结论：根据临床症状、起病特征可初步判断病变类型,争取早期正确诊断、早期治疗,为     

外伤性脊髓损伤的MRI表现与临床对照分析

目的评价MRI在脊髓损伤的临床应用价值。资料与方法回顾性分析66例脊髓损伤的临床及MRI表现，着重分析脊髓损伤的MRI征象与病理、临床的关系。结果MRI显示椎体压缩性骨折51例，椎间盘脱出2例，椎体骨折并椎问盘脱出5例；椎体部分性滑脱20例，完全性滑脱1例。显示脊髓完全性截断4例，部分性截断1例，脊髓受压4l例。62例脊髓连贯者59例显示脊髓信号异常。59例有完整的住院治疗记录，治疗后显示病情好转25例，症状无改善26例，死亡8例。结论MRI检查能明确脊髓有无损伤以及损伤的程度，有助于临床治疗措施的选择以及对预后的评估。     

Spinal pilocytic astrocytoma: MR imaging findings at first presentation and following surgery

Objective

The objective of this article is to describe MR imaging findings of spinal cord pilocytic astrocytomas at first presentation and following neurosurgery and to discuss briefly some of the most common differential diagnoses.

Conclusion

MR imaging findings in medullary pilocytic astrocytomas consist generally of focal or diffuse cord-enlarging masses that are irregularly shaped, accompanied by cystic elements and hydromyelia, present different degrees of contrast enhancement, high water diffusivity and a propensity for the thoracic and cervical cord.     

伽玛刀低剂量体积分割治疗颅底大型脑膜瘤

目的:研究伽玛刀低剂量体积分割治疗颅底大型脑膜瘤的治疗效果及并发症。方法:自1997～2009应用OUR-旋转式伽玛刀体积分割治疗颅底大型脑膜瘤共7例,其中男性4例,女性3例,年龄53～80岁。2例系术后复发,手术病检证实为脑膜瘤;5例为临床及影像诊断为脑膜瘤。肿瘤直径为42～60 mm,所有患者在伽玛刀第一次规划时设定体积分割范围及分割次数,射线单次照射病灶直径为25～30 mm,分割次数为2～3次。单次治疗周边剂量8～11 Gy,间隔时期3～9月。结果:在分割照射结束后开始随访,随访2～10年,随访7例。肿瘤生长控制率为85.6%(6/7),其中明显缩小1例,无变化5例。瘤体增大1例。临床症状改善为3例,症状无改变为3例,加重1例,症状加重系瘤体增大所致。结论:颅底大型脑膜瘤首选手术治疗,但对身体状态难以耐受手术或拒绝手术的老年患者,伽玛刀低剂量体积分割治疗是可供选择的方法。     

急性脊髓损伤后运动诱发电位与MRI表现相关性研究

目的：研究实验性脊髓急性创伤后动态MR表现和运动诱发电位评分间的相关性。材料和方法：23只家兔建立脊髓液压损伤模型，其中对照组5只，脊髓按不同损伤程度分A、B两纽，各9只．于伤后24h、72h、7d行MRI与运动诱发电位评分。结果：脊髓损伤A组创后24h出现高低混杂信号．MEP未引出且随时间延睫未见恢复；72h出现血肿信号特征．7d创区大部分坏死信号．其功能未见恢复。损伤B组24h见点状水肿信号．MEP潜伏期明显延长．72h-7d范围扩大，MEP表现山脊髓功能部分恢复。结论：脊髓功能的MEP评判准确地提供了量化标准。高场MRI发现72h表现出脊髓血肿的信号提示脊髓功能缺失严重，而72h的点状高信号提示脊髓不完全损伤．并可有恢复。     

经皮穿刺椎体成形术治疗椎体病变的临床价值

目的:探讨经皮穿刺椎体成形术治疗椎体病变的临床价值。方法:对35例共43个椎体行PVP,其中血管瘤5例累及7个椎体,骨质疏松致压缩性骨折30例累及36个椎体。于C臂X光机监控下,经椎弓根入路,将骨水泥(甲基丙烯酸树脂多聚体为粉剂,甲基丙烯树脂单体为液体)粉剂与液体按体积比3∶1调成糊状,用10ml注射器匀速注入病变椎体。结果:PVP术后,CT示骨水泥为斑片状分布9个,团状分布34个。CT和平片随访观察骨水泥密度、形态与术后所见无变化,未见椎体进一步压缩。33例(94.3%)患者疼痛消失,2例(5.7%)疼痛减轻。治疗效果采用WHO标准有效率(完全缓解和部分缓解)为100%。结论:PVP是一种有价值的治疗椎体病变的方法,能迅速缓解疼痛,加固椎体,增强脊柱稳定性。     

脊柱闭合不全的MR影像诊断：（一）开放性脊柱闭合不全

报告了６２例脊柱闭合不全的ＭＲ影像资料。根据骨缺损的程度，分为开放性脊柱闭合不全和隐性脊柱闭合不全。本组开放性脊柱闭合不全包括后位脊膜膨出５例、脂肪脊髓脊膜膨出１２例、脊髓囊状突出２例。根据突出物内ＭＲ信号强度的特点，ＭＲ可作出正确诊断。笔者认为，ＭＲ对开放性脊柱闭合不全的诊断和分类具有较高的价值，特别是在矢状面图像上，可清楚地显示病变的全貌。     

脊柱结核的MRI评价

目的：分析脊柱结核的ＭＲＩ特征。材料和方法：总共１８例证实为脊柱结核的患者行ＭＲＩ检查（男１２例，女６例，年龄１９－７６岁）。结果：ＭＲＩ所见：（１）相邻椎体受累１６例（８８．９％）。（２）韧带下及椎旁脓肿１２例（６６．７％）。（３）椎管内侵犯５例（２７．８％）。（４）１８例共４４个椎体受累，在Ｔ１加权上呈低信号（３４／４４），Ｔ２加权上呈高信号（３２／４４）。（５）１８例中有１６例见椎间盘异常（形态或信号），受累椎间盘在Ｔ２加权上信号多变。结论：脊柱结核的ＭＲＩ征象对诊断极有帮助并能为外科手术提供详细的解剖资料。     

Biomechanics of the spine. Part II: Spinal instability

Spine stability is the basic requirement to protect nervous structures and prevent the early deterioration of spinal components. All bony and soft spinal components contribute to stability, so any degenerative, traumatic or destructive lesion to any spinal structure gives rise to some degree of instability.     

椎体肿瘤椎体重建术前选择性动脉栓塞临床应用研究

目的 探讨选择性动脉栓塞后肿瘤椎体切除重建的疗效及价值. 资料与方法 选择有脊髓压迫症状的胸腰椎肿瘤患者24例,分成对照组(n=11)和研究组(n=13).对照组直接行肿瘤椎体切除人工椎体置换椎体重建术;研究组先行肿瘤供血动脉栓塞化疗后,再行肿瘤椎体重建术. 结果 对照组4例手术失败,7例手术成功,成功率57%,术中平均出血量为3385 ml、平均手术时间5 h;研究组13例肿瘤椎体全部手术切除成功,成功率达100%,术中平均出血量为842 ml,平均手术时间3 h.研究组与对照组比较术中平均出血量、手术时间差异有统计学意义(P＜0.01).所有患者随访6～36个月神经功能恢复满意,椎体重建稳定性良好. 结论 术前胸腰椎动脉栓塞便于肿瘤椎体切除及重建,可提高患者的生存质量.     

脊髓血管畸形的MRI诊断(附3例报告及文献复习)

目的：评价ＭＲ成像对脊髓血管畸形的诊断价值。方法：共３例，其中２例为硬脊膜动静脉瘘，１例为根脊膜血管畸形，在１．５Ｔ磁共振机上应用表面线圈作高分辨ＭＲ成像，其结果与选择性脊髓动脉造影进行对照。结果：ＭＲ不仅可显示畸形血管特征性的快速流空现象，而且还可显示畸形血管远端髓内长Ｔ１、长Ｔ２信号改变。ＭＲＩ与血管造影结果基本符合。结论：ＭＲ成像是评价脊髓血管畸形十分敏感和有效的方法     

多层螺旋CT评价脊柱融合模型成骨过程的研究

目的 分析自体骨成骨与硫酸钙成骨的CT表现,结合同期病理学结果,探讨影像改变的病理机制.材料与方法 20只健康家兔建立腰椎融合模型,一侧植入医用硫酸钙,对侧植入自体髂骨.于术后3、6、12周行手术部位多层螺旋CT (MSCT)检查,观察植入物与自体骨融合状况.于术后12周,根据CT表现计算植骨融合率及MSCT评估腰椎融合的敏感度、特异度、阳性预测值(PPV)及阴性预测值(NPV).术后3、6周各随机处死1只家兔,获得同期病理对照,术后12周处死剩余18只家兔,获得最终时间点病理对照.结果 MSCT评估硫酸钙植骨一侧腰椎融合的敏感度、特异度均为100.0％,自体髂骨植骨侧分别为94.1％和100.0％.术后12周,硫酸钙植骨一侧融合率为88.9％ (n=16),PPV为94.1％,NPV为100.0％;自体髂骨植骨一侧融合率为94.4％ (n=17),PPV为100.0％,NPV为50.0％,两侧融合率差异无统计学意义(P＞0.05).结论 MSCT能够有效评价脊柱融合术后骨移植材料的成骨表现.     

两种脊柱内固定方法疗效和生物力学评价

报告两组手术开放复位固定治疗脊柱损伤的临床疗效和生物力学测试比较，Ａ组哈氏棒加钢丝节段固定１７例；Ｂ组爱德华兹大棒内固定６０例。结果（１）两组方法对畸形角的短正均十分明显（Ｐ＜０．０１），Ｂ组优于Ａ组（Ｐ＜０．０１）。（２）移位百分率的改进亦显著（Ｐ＜０．０１），Ｂ组优于Ａ组（Ｐ＜０．０１）。（３）压缩椎体高度的恢复Ｂ组优于Ａ组（Ｐ＜０．０１）。（４）神经功能恢复一级以上Ａ组为８２％，Ｂ组为９０％     

Spinal cord tumors: gadolinium-DTPA-enhanced MR imaging

Summary To assess the utility of gadolinium-DTPA (Gd) and of MR imaging in the evaluation of spinal cord tumors, ten consecutive patients were prospectively evaluated. T1-proton density-, and T2-weighted images were obtained in sagittal or axial planes. T1-weighted images were obtained before and after intravenous administration. Five tumors were within the cervical spinal cord; 3 neoplasms were within the thoracic cord; 1 neoplasm extended from the cervical to the thoracic cord and 1 neoplasm extended from the cervical cord to the conus medullaris. Four tumors were ependymomas; 3 were astrocytomas; 1 was an hemangioblastoma, and 1 was a metastatic malignant peripheral nerve sheath tumor. The remaining patient died prior to spinal surgery and no autopsy was obtained. Of theprecontrast sequences, tumors were best evaluated using T1-weighted images. Abnormal findings included cord widening, presence of a tumor mass, intratumoral or other associated cyst(s), and hemorrhage. Nevertheless, T1-weighted images obtainedfollowing the administration of GD were superior relative to all other pre- and post-contrast sequences for defining tumor margins, characterizing cyst(s) and delineating tumor masses. Based primarily on their appearance on post-contrast T1-weighted images, tumor-associated cysts could be subcategorized into 3 types: intratumoral cysts (foundwithin the contrast-enhancing soft tissue mass); nonenhancing extratumoral cysts (found either rostral or caudal to the enhancing tumor mass); and enhancing extratumoral cysts (having an enhancing wall or containing an enhancing nodule). Our results indicate that T1-weighted MR images obtained both before and after administration of Gd are sufficient for characterizing the varying components of intramedullary spinal cord tumors. This information assists in treatment planning and follow-up of patients with these tumors.Presented in abstract form at meetings of the American Academy of Neurology, Chicago, Illinois, April, 1989