单发脑转移瘤的MRI诊断

目的:探讨单发脑转移瘤(solitary brain metastasis,SBM)的MRI表现,提高对其诊断的准确性。方法:回顾性分析经临床综合确诊的38例SBM的MRI平扫及增强表现,分析病灶的部位、大小、瘤周水肿程度和瘤体的强化特点。结果:本组38例SBM中,发生于幕上31例,其中位于脑皮质和皮质下区28例;幕下7例。瘤体直径＜1.0cm有12例,1.0cm-3.0cm 19例,＞3.0cm 7例。增强扫描所有病灶均出现强化,其中结节型强化19例,环型强化11例,混合型强化8例。瘤周无水肿7例,轻度水肿11例,中度水肿13例,重度水肿7例。结论:SBM的MRI表现具有一定的特征性,MRI增强扫描对其诊断和鉴别诊断具有重要价值。     

脑转移瘤MRI扫描技术的探讨

目的探讨最佳脑转移瘤MRI扫描技术.方法收集35例经病理及手术证实原发肿瘤,经不同扫描参数对比,选出最佳脑转移瘤MRI扫描技术.结果增强扫描不仅可以提高病灶检出率,还可以发现MRI平扫阴性早期脑转移瘤.采用水抑制技术(FLAIR)和多方位扫描利于发现不典型脑转移瘤,并与原发肿瘤鉴别.结论MRI增强扫描,FLAIR及多方位扫描相结合,可提高脑转移瘤检出水平.     

增强MR对脑转移瘤诊断的作用

目的通过MR增强扫描对脑转移瘤影像表现的分析,提高MR增强对脑转移瘤珍断重要性的认识.方法 MR成像使用ELSCINT0.5T超导磁共振系统,头线圈.收集30例平扫及增强后不同影像表现脑转移瘤作回顾性分析.结果平扫发现脑转移瘤25例,占83%(25/30).增强扫描均出现异常对比增强病灶.结论脑转移瘤是颅内常见恶性肿瘤.MRI增强扫描可以清楚地显示转移灶.     

35例脑转移瘤MRI分析

目的回顾性分析经临床、手术及病理证实的35例脑转移瘤的MRI表现.方法35例病人,男27例,女8例,年龄29～77岁.均采用横轴位、矢状位、冠状位及增强扫描.结果35例病人125个病灶,瘤周水肿89个.增强前发现病灶86个.增强后发现病灶125例.脑转移实质性病灶84个,部分囊变坏死19个,完全囊变22个.原发恶性肿瘤肺癌22例,脑内胶质瘤5例,肾癌、结肠癌、鼻咽癌及淋巴肉瘤各2例.结论脑转移瘤中肺癌转移最多见;多发性脑转移瘤可有多种形态;小脑出现占位性病变应考虑到转移瘤的可能.     

不同病理类型肺癌脑转移瘤的CT平扫及增强扫描特征

目的 探讨不同病理类型肺癌脑转移瘤的CT平扫及增强扫描特征.方法 回顾性分析40例肺癌脑转移瘤患者的临床资料,所有患者均接受了颅脑CT平扫及增强扫描,观察脑转移瘤的分布情况,分析不同病理类型肺癌脑转移瘤的病灶数目、密度特征、瘤周水肿情况及强化特征.结果 40例肺癌脑转移瘤患者中,CT平扫及增强扫描共显示165处脑转移灶,其中17例腺癌患者检出75处转移灶,12例鳞癌患者检出41处转移灶,7例小细胞癌患者检出40处转移灶,2例大细胞癌患者检出5处转移灶,2例腺鳞癌患者检出4处转移灶.40例肺癌脑转移瘤患者中,以多发病灶为主,占62.5％(25/40);瘤周水肿多为中～重度,占77.5％(31/40).腺癌及小细胞癌脑转移瘤中,多发转移灶的比例较高,分别为76.5％和71.4％;鳞癌脑转移瘤中,单发转移灶的比例较高,为58.3％.腺癌及小细胞癌脑转移瘤中,混杂密度比例较高,分别为40.0％和35.0％;鳞癌、大细胞癌及腺鳞癌脑转移瘤中,等密度比例较高,分别为43.9％、40.0％和50.0％.不同病理类型比较,腺癌中合并出血的比例最高,为56.0％;鳞癌中未合并出血的比例最高,为82.9％.肺癌脑转移瘤的强化方式以结节性强化比例最高(45.5％),环形强化次之(37.0％),不强化的比例最低(2.4％).腺癌脑转移瘤中,环形强化的比例最高,为50.7％;鳞癌、小细胞癌、大细胞癌、腺鳞癌脑转移瘤中,结节性强化的比例均最高,分别为68.3％、37.5％、60.0％和50.0％.结论 不同病理类型肺癌脑转移瘤的CT平扫及增强扫描具有一定的特征性.     

1HMRS对脑转移瘤的诊断价值

目的：探讨氢质子磁共振波谱（proton magnetic resonance spectroscopy,1 H MRS）对脑转移瘤的诊断价值。方法：收集术后病理或临床证实脑转移瘤32例。所有患者MRS前均行MR平扫及增强扫描。3．0T MR多体素波谱（TE 144ms）扫描,分别于肿瘤实质、瘤周水肿及正常脑实质取感兴趣区（VOI）,测量代谢物浓度,计算Cho／Cr、NAA／Cr、Cho／NAA值,比较肿瘤实质与正常脑实质、瘤周水肿与正常脑实质代谢物比值的差异,采用配对t检验。观察肿瘤实质是否出现1．3ppm脂峰（Lip）及可流动脂质。结果：肿瘤实质与正常脑实质代谢物比较,Cho／Cr增高、NAA／Cr降低、Cho／NAA增高,差异有统计学意义（P均＜0．05）。瘤周水肿与正常脑实质代谢物比较,Cho／Cr略有增高,NAA／Cr 略有降低,差异无统计学意义（P均＞0．05）;Cho／NAA 增高,差异有统计学意义（P＜0．05）。32例中24例出现Lip,出现率75％,15例出现可流动脂质,出现率46．9％。结论：脑转移瘤的MRS具有一定特征,脂峰及可流动脂质的出现有助于脑转移瘤的诊断。     

不同容积成像技术MR增强扫描对检出脑转移瘤的价值比较

目的：探讨3D Bravo与Cube序列在脑转移瘤诊断中的价值,比较两种序列的优缺点。方法收集临床因怀疑脑转移而行3D Bravo、Cube容积采集技术MR增强扫描的病例25例。先由两位影像医师共同阅片确定转移瘤的位置与数目,以及有无脑膜转移。再由另一位影像医师对所有病例的Bravo与Cube序列图像分别进行判读,包括图像质量、转移病灶位置及数目、有无脑膜转移,比较病灶与正常灰白质的信号强度相对对比度（CR）,并对结果进行统计学分析。结果入组25例病例中共发现转移病灶221枚;Bravo序列发现转移病灶206枚（93.2%）,漏诊15枚（6.8%）,误诊1枚（0.4%）;Cube序列发现转移病灶214枚（96.8%）,漏诊7枚（3.2%）,误诊3枚（1.4%）;1例软脑膜转移病例,Cube序列诊断正确,Bravo序列出现漏诊;Bravo序列中病灶与正常灰质、病灶与正常白质的信号强度CR明显高于Cube序列（P=0.001）。结论 Bravo序列中病灶与正常灰白质的信号强度CR均明显高于Cube序列。对于近皮层的微小转移病灶以及软脑膜转移,Bravo序列有可能漏诊,Cube序列中部分病灶强化程度较低,应注意结合平扫序列综合考虑。     

Gd-DTPA在脑转移瘤诊断中的应用及护理体会

目的:评价Gd-DTPA增强扫描在正确诊断不同表现的脑转移瘤中的作用,以及进一步探讨MRI增强前后的准备与护理方法。方法:对96例使用Gd-DTPA患者,增强前后病变MR表现进行分析比较。结果:96例中共检出瘤体灶148个,强化扫描比平扫多发现68个,在148个病灶中,呈弥散快速强化的93个,呈环状结节状强化的有55个,均为明显强化。结论:Gd-DTPA强化扫描对脑转移瘤的诊断价值是肯定的,在区别瘤体与水肿,坏死、囊变及显示微小病灶方面作用显著。加强扫描前后的护理,对保证受检者的安全及增强效果具有重要作用。     

MRI与核素骨显像对脊柱转移瘤诊断价值的对比观察

目的：比较ＭＲＩ与核素骨显像对诊断脊柱转移瘤的价值。方法：对４８例同时进行了ＭＲＩ和核素骨显像并确诊为脊柱转移瘤的 例,以ＭＲＩ扫描野内脊柱为观察目标,人为地将脊柱分为颈椎、上段胸椎（Ｔ１￣４）、中段胸椎（Ｔ５￣８）、下段胸椎（Ｔ９￣１２）、上段腰椎（Ｌ１、２）、下段腰椎（Ｌ３￣５）、骶椎,比较ＭＲＩ与核素显像对该部位病变的显示情况。结果：４８例患者,ＭＲＩ共检查１７３个区段,其中显示阳怀的８４个区段中共计２１０个病灶,确诊（“真阳性”）２０６个,漏诊（“假阳性”）４个,无“假阳性”,其诊断敏感性为９８．１％。核素骨显像与之相对应的８４个区段上,病灶确诊（“真阳性”）１４２个,漏诊（“假阳性”）４９例,另有“假阳性”５２个,其诊断敏感性为７３．８％。结论：在显示脊柱转移瘤方面,ＭＲＩ较核素骨显像更具敏感性和特异     

MRI动态增强扫描在肝转移瘤诊断及血供分析中的应用(附60例病例报告)

目的:探讨MRI动态增强扫描尤其是动脉期扫描在检测肝转移瘤中的临床意义.方法:回顾性分析60例肝转移瘤560个病灶在MRI动态增强各期的图像表现,计算平扫及动态增强各序列显示的病灶数目,分析其血供类型及强化方式.结果:肝转移瘤在动脉期、门脉期及静脉期的检出率分别为95%、87%、86%;56个富血供转移瘤仅在动脉期显示.52%的乏血供转移瘤和89%富血供转移瘤在动脉期强化更明显.周边环形强化是肝转移瘤在动脉期的主要强化方式.结论:MRI多期增强扫描,尤其动脉期扫描能够较好的检测出肝转移瘤并分析其血供类型,从而为临床治疗方案的选择及预后评价提供参考依据.     

Extent of perilesional edema differentiates radionecrosis from tumor recurrence following stereotactic radiosurgery for brain metastases

Background

Differentiation of tumor recurrence from radionecrosis is a critical step in the follow-up management of patients treated with stereotactic radiosurgery (SRS) for brain metastases. A method that can reliably differentiate tumor recurrence from radiation necrosis using standard MR sequences would be of significant value.

Methods

We analyzed the records of 49 patients with 52 brain metastases treated with SRS who subsequently underwent surgical resection of the same lesion. Forty-seven of the lesions had preoperative MRI available for review (90%), including T1 postcontrast, T2, and fluid attenuated inversion recovery sequences. Pre-SRS and preoperative lesion and edema volumes were manually contoured and measured in a blinded fashion using radiation treatment planning software. A neuropathologist analyzed samples for the presence of tumor and/or radiation necrosis.

Results

Longer time between SRS and resection (P < .001) and a larger edema/lesion volume ratio (high T2/T1c, P = .002) were found to be predictive of radionecrosis as opposed to tumor recurrence. Using a cutoff value of 10 for the edema/lesion volume ratio, we were able to predict the presence of tumor with a positive predictive value of 92%, which increased to 100% when looking only at patients who underwent resection <18 months following SRS.

Conclusions

On follow-up imaging, lesions with a high edema/lesion volume ratio and lesions that progress later after SRS are more likely to contain radionecrosis. These indices may help guide clinical decision making in the context of evolving lesions after SRS for brain metastases and thereby avoid unnecessary interventions.     

Detection of brain metastases from small cell lung cancer: consequences of changing imaging techniques (CT versus MRI)

BACKGROUND: The aims of this study were to show 1) the effect of changing from computed tomography (CT) to magnetic resonance imaging (MRI) on the prevalence of detected brain metastases (BM) in patients with newly diagnosed small cell lung cancer (SCLC); 2) the difference in survival between patients with single and multiple BM; and 3) the effect of the change in patient labeling on eligibility for prophylactic brain irradiation. METHODS: From 1980 to 2004, 481 consecutive patients with SCLC were enrolled. Brain imaging was routinely performed after diagnosis of SCLC. At the start of 1991, MRI replaced CT in almost all patients. All patients were regularly examined by a neurologist. RESULTS: The prevalence of detected BM was 10% in the CT era and 24% in the MRI era. In the CT era, all detected BM were symptomatic, whereas in the MRI era, 11% were asymptomatic. In both periods, patients labeled as single BM survived longer than those labeled as multiple BM. For patients labeled as single BM or multiple BM, survival was longer in the MRI era than in the CT era. The proportion of patients who were eligible for prophylactic cranial irradiation was lower in the MRI era. CONCLUSIONS: The estimated prevalence of BM increases when MRI is used instead of CT. Patients with a detected single BM survive longer than patients with multiple BM. The apparently increased survival in the MRI era can be attributed to the "Will Rogers phenomenon". The use of MRI makes fewer patients eligible for prophylactic cranial irradiation.     

Diagnostic Accuracy of MRI Compared to CCT in Patients with Brain Metastases

Objectives. In patients with extracranial neoplasms, the occurrence and number of brain metastases (BM) are critical for further diagnostic approaches and therapeutic strategies and the patient's prognosis. Although widely accepted, there is surprisingly little evidence in the literature that MRI is superior to CCT. Therefore, in patients with solitary BM according to diagnostic contrast-enhanced computed tomography (CCT), we investigated, what additional information could be gained by contrast-enhanced magnetic resonance imaging (MRI). Methods/Results. Among 55 patients with solitary BM according to CCT, 17 had multiple BM on MRI (31%) and 38 had solitary BM in both. Based on a presumed binomial distribution of our data, we calculated a rate of at least 19% of patients with solitary BM on CCT, in which MRI would show multiple lesions (p=0.05). The two main characteristics for BM missed by CCT were the smaller diameter, which averages 2cm less than in BM identified with both modalities, and a preferential frontotemporal location. Conclusion. MRI is indeed superior to CCT in the diagnosis of BM the essential reasons besides detection of smaller lesions being a better soft tissue contrast, significantly stronger enhancement with paramagnetic contrast agents, the lack of bone artifacts, fewer partial volume effects, and direct imaging in three different planes. Therefore, MRI is indispensable in the diagnostic workup of patients with BM for choosing the optimum therapeutic approach, especially with regard to the decision whether to operate or to primarily irradiate the patient's metastases.     

咽旁间隙肿瘤的CT和MRI诊断价值

目的分析咽旁间隙肿瘤的CT及MRI表现,以提高该部位病变的诊断及鉴别诊断水平。方法回顾性分析54例经病理证实的咽旁间隙肿瘤的CT及MRI表现。结果神经鞘瘤形态较规则（85．7％）,涎腺肿瘤形态多不规则（63．2％）,二者边界多清楚。涎腺肿瘤位于茎突前方18例（94．7％）,神经鞘瘤位于颈鞘内26例（92．9％）。24例神经鞘瘤使咽旁间隙向两侧移位（85．7％）,涎腺肿瘤多向前、内侧移位。涎腺肿瘤中12例（63．2％）小部分伸人腮腺深叶。神经鞘瘤多位于二腹肌后腹的深面（96．4％）,涎腺肿瘤多位于二腹肌后腹的浅面（68．4％）。结论肿瘤与茎突、咽旁脂肪间隙、颈鞘、腮腺、二腹肌后腹的关系及肿瘤密度／信号及强化特点对咽旁间隙肿瘤的定位、定性诊断有重要的价值。     

Evaluation of MRI T1-based treatment monitoring during laser-induced thermotherapy of liver metastases for necrotic size prediction

Purpose: The aim of this study was to evaluate the accuracy of real-time magnetic resonance imaging (MRI) T1-based treatment monitoring for predicting volume of lesions induced by laser-induced thermotherapy (LITT) of liver metastases.

Materials and methods: This prospective study was approved by the institutional review board and informed consent from all included patients was obtained. In 151 patients, 237 liver metastases were ablated during 372 LITT procedures. 1.5T MRI treatment monitoring was performed based on longitudinal relaxation time (T1) using fast low-angle shot (FLASH) sequences. Patients underwent additional contrast-enhanced MRI directly after LITT, 24?h after the procedure and during follow-up at 3, 6 and 12 months. The amount of energy necessary to induce a defined necrotic area was investigated within the various liver segments.

Results: The total amount of energy applied during LITT varied from 6.12–225.32?kJ (mean 48.96?kJ). Ablation in liver segments 5 (2.12?kJ/cm³) and 8 (2.16?kJ/cm³) required the highest energy. The overall pre-ablative metastasis volume ranged from 0.5–51.94?cm³ (mean 1.99?cm³, SD 25.49?cm³) while the volume measured in the last available T1 image varied from 0.78–120?cm³ (mean 26.25?cm³, SD 25.66?cm³). Volumes measured via MRI T1-based treatment monitoring showed a stronger correlation with necrosis 24?h after LITT (r?=?0.933, p?r?=?0.888, p?Conclusions: Real-time MRI T1-based treatment monitoring during LITT of liver metastases allows for precise estimation of the resulting lesion volume and improves control of the energy necessary during ablation.