肝脏脂肪含量MRI定量诊断与病理对照研究

目的探讨频率饱和反转恢复序列(spectral saturation inversion recovery,SPIR)、梯度回波化学位移MRI及磁共振氢谱(proton magnetic resonance spectroscopy,1H-MRS)在定量分析肝脏脂肪含量中的价值。方法对31例健康自愿者及22例可获得肝脏标本的病例行常规T1加权和T2加权(不压脂+压脂)、梯度回波T1加权同相位/反相位(in-phase/opposed-phase,IP/OP)成像及肝脏1H-MRS检查。测得T1WI和T2WI压脂前、后及IP/OP的信号强度值(SInonfat1、SIfat1、SInonfat2、SIfat2、SIin及SIout),计算相对信号强度(relative signal intensity,RSI1及RSI2)和脂变指数(fat index,FI);测得1H-MRS的峰值及峰下面积,计算肝细胞相对脂肪含量(relative lipid con-tent,RLC)。病例组22例患者于MRI扫描后接受肝脏外科手术切除,切下的肝脏进行病理组织学检查,并用图像分析软件测量肝细胞中脂变细胞百分比(proportion of fatty degenerative cells,PFDC)。结果①脂肪肝组RSI1、FI及RLC的平均值均高于非脂肪肝组(P<0.05),但RSI2的平均值2组间差异无统计学意义(P>0.05)。②脂肪肝不同病理分级间RLC的差异具有统计学意义,且随脂肪肝病理级别的增加而增高(P<0.05);随着病理级别的增加,RSI1及FI逐渐增高,但差异无统计学意义(P>0.05);RSI2在脂肪肝不同病理分级间的差异亦无统计学意义(P>0.05)。③FI及RLC与PFDC之间存在线性正相关关系(r=0.468,P=0.027;r=0.771,P<0.000 1);RSI1及RSI2与PFDC之间无相关性(r=0.411,P=0.057;r=0.191,P=0.392)。结论 SPIR、梯度回波化学位移MRI及1H-MRS三种方法可在一定程度上区分有无脂肪肝;1H-MRS有助于脂肪肝的分级;在肝脏脂肪含量定量分析方面,1H-MRS较梯度回波化学位移MRI更具优越性,有助与肝脏脂肪的量化分析;而SPIR价值有限。     

3.0 T ~1H-MRS定量分析评估脂肪肝治疗效果的初步研究

目的探讨在3.0 T MRI中运用氢质子波谱成像(1 H-MRS)技术评估脂肪肝治疗效果的可行性。方法收集临床确诊并治疗的脂肪肝患者26例,分别于治疗前、治疗后3和6个月各行1次1 H-MRS检查,测得1 H-MRS的水峰峰值和脂肪峰峰值、水峰峰下面积和脂肪峰峰下面积,计算肝细胞相对脂肪含量1(RLC1)及相对脂肪含量2(RLC2);同期测量患者的甘油三酯、γ-谷氨酰转肽酶、腹围及体重指数,将其拟合成临床脂肪肝指数(fatty liver index,FLI)。以FLI为参照标准,对不同时间点1 H-MRS所测得肝脏脂肪含量进行统计学分析。结果采用配伍设计的方差分析,治疗前、治疗后3和6个月的RLC1、RLC2值比较差异有统计学意义(P<0.05);用SNK法做两两检验,治疗前RLC1、RLC2值均分别明显高于治疗后3个月或治疗后6个月的RLC1、RLC2值(P<0.05)。RLC1、RLC2与FLI进行秩相关性分析,均呈正相关性(r=0.476,P<0.001;r=0.475,P<0.001)。可靠性分析显示,治疗前的组内相关系数均≥0.75,可重复性好。结论 1 H-MRS定量分析评估脂肪肝治疗效果具有可行性,并且是一种无创的定量监测方法。     

3.0 T ~1H-MRS定量分析评估脂肪肝治疗效果的初步研究3.0 T^1H-MRS定量分析评估脂肪肝治疗效果的初步研究

目的探讨在3.0 T MRI中运用氢质子波谱成像（1 H-MRS）技术评估脂肪肝治疗效果的可行性。方法收集临床确诊并治疗的脂肪肝患者26例,分别于治疗前、治疗后3和6个月各行1次1 H-MRS检查,测得1 H-MRS的水峰峰值和脂肪峰峰值、水峰峰下面积和脂肪峰峰下面积,计算肝细胞相对脂肪含量1（RLC1）及相对脂肪含量2（RLC2）;同期测量患者的甘油三酯、γ-谷氨酰转肽酶、腹围及体重指数,将其拟合成临床脂肪肝指数（fatty liver index,FLI）。以FLI为参照标准,对不同时间点1 H-MRS所测得肝脏脂肪含量进行统计学分析。结果采用配伍设计的方差分析,治疗前、治疗后3和6个月的RLC1、RLC2值比较差异有统计学意义（P〈0.05）;用SNK法做两两检验,治疗前RLC1、RLC2值均分别明显高于治疗后3个月或治疗后6个月的RLC1、RLC2值（P〈0.05）。RLC1、RLC2与FLI进行秩相关性分析,均呈正相关性（r=0.476,P〈0.001;r=0.475,P〈0.001）。可靠性分析显示,治疗前的组内相关系数均≥0.75,可重复性好。结论 1 H-MRS定量分析评估脂肪肝治疗效果具有可行性,并且是一种无创的定量监测方法。 更多     

3.0T ~1H-MRS、梯度双回波和三回波技术在定量评估脂肪肝治疗效果中的价值

目的探讨3.0T磁共振氢谱(~1H-MRS)、梯度双回波和三回波技术在定量评估脂肪肝治疗效果中的价值。方法前瞻性收集四川省医学科学院·四川省人民医院2017年8月至2018年5月期间收治的30例经CT或超声确诊的脂肪肝患者作为研究对象,于治疗前和治疗后3个月各行1次梯度双回波、三回波及~1H-MRS检查,并计算脂变指数(fat index,FI)及肝细胞相对脂肪含量(relative lipid content,RLC)。同期测量血液生化指标、腹围、体质量指数(body mass index,BMI),并拟合成临床脂肪肝指数(the fatty index,FLI)。以FLI为参考标准,对治疗前后的MRI测得结果进行统计学分析。结果干预治疗后,与治疗前比较,FLI、FI_双、FI_三及RLC均降低(t=5.281,P0.001;Z=–3.651,P0.001;Z=–3.630,P0.001;Z=–4.762,P0.001)。治疗前,FI_双和FI_三与FLI均呈正相关(r_s=0.413,P=0.023;r_s=0.396,P=0.030),治疗后FI_双和FI_三与FLI亦均呈正相关(r_s=0.395,P=0.031;r_s=0.519,P=0.003),以治疗后的FI_三与FLI的相关系数为最高;治疗前及治疗后RLC与FLI之间的相关性均无统计学意义(P0.05)。结论采用~1H-MRS、梯度双回波和三回波技术定量评估脂肪肝的治疗效果是可行的,且梯度三回波技术的准确性更好,技术上容易实现,更适合在临床广泛开展。     

STEAM和PRESS序列在脂肪肝定量诊断中应用价值的对比研究

目的比较STEAM和PRESS序列在脂肪肝定量诊断中的应用价值。方法选用45只健康新西兰大白兔,采用高脂高糖饲料加酒精饮料建立不同程度脂肪肝模型,采用STEAM和PRESS两种脉冲序列对同一位置、同一体素进行磁共振氢波谱扫描,共观察和测定9个指标,并逐一进行配对对照研究。结果经STEAM和PRESS两种定位方法测定,肝内水化学位移、脂肪化学位移、脂/水峰值比率、脂/水波峰下面积比率、脂肪百分比组间均数无显著性差异（P〉0.05）;而肝内水峰峰值、脂峰峰值、水波峰下面积、脂波峰下面积组间均数存在显著性差异（P〈0.05）,即STEAM序列下上述各指标均数明显低于PRESS序列,信号相对损失率平均约47.9%;且STEAM序列下各观测指标与脂肪肝病理分级的相关性普遍低于PRESS序列。结论PRESS较STEAM序列更适用于肝内脂肪含量的定量研究。     

肝移植术供体肝脏及其肝穿活检临床病理观察分析

目的 探讨肝移植术时供体肝脏的病理组织学变化与其移植术后肝脏病理改变的关系以及对预后的影响.方法 该研究对87例肝移植术供肝零时活检和术后肝脏活检标本进行病理组织观察分析.结果 (1)87例供肝零时活检肝细胞变性100%;(2)肝窦内皮细胞损伤41.3%;(3)肝细胞脂肪变性18.3%;(4)肝细胞坏死10.3%.结论 供肝肝细胞变性最常见,大多可逐渐恢复.肝窦内皮细胞损伤是观察缺血再灌注损伤的重要指标.中到重度小泡性肝细胞脂肪变是可用的.肝移植术后肝细胞坏死有逐渐加重、范围逐渐增大的趋势时,可使移植肝功能丧失的危险性增加.肝移植术零时供肝活检及术后肝活检的对比观察具有十分重要的诊断价值.     

脂肪肝的中医病机演变探讨

中医学里面没有脂肪肝这一病名,在西医通常分酒精性和非酒精性脂肪性肝病(NAFLD)两大类[1],是一组以实质性肝细胞脂肪变性和脂肪贮积为特征的临床病理综合症.脂肪肝已经成为临床常见病之一,随着病情的进展,临床表现,以及组织学的改变,大致可以分为单纯性脂肪肝、脂肪性肝炎、脂肪性纤维化、肝硬化.绝大多数脂肪肝患者无症状,常在体检中发现,当组织学脂肪沉积于肝脏越过30%时,B超可以栓查出脂肪肝,肝脏脂肪含量达到50%以上时,B超检查确诊率可以达到90%[2].B超检查简便、价廉、无创伤,已作为诊断脂肪肝和监测其发展过程的首选.部分病人自觉右上腹不适,隐痛或上腹胀痛等非特异症状,严重脂肪肝可出现瘙痒、食欲减退、恶心、呕吐等症状.进至肝硬化患者可出现腹水、食管-胃底静脉破裂出血、水肿以及肝性脑病等,少数患者有肝掌、蜘蛛痣等体征.     

腹腔镜胆囊切除术中高频电刀对肝脏损伤的影响

目的　研究腹腔镜胆囊切除术肝脏病理与酶学变化的原因。方法　 1 999～ 2 0 0 1年我院收治的 6 9例胆囊结石随机分组。常规应用单极高频电刀行腹腔镜胆囊切除术 35例 (电切组 ) ,胆囊床普遍电凝处理 ;对照组应用剪刀行腹腔胆囊切除术 34例 (剪切组 ) ,钛夹钳闭止血 ;手术结束时每组抽样取 5例胆囊床底部边缘肝组织 1 cm× 1 cm一块 ,病理切片 ,光镜观察肝细胞的变化 ,全部受试者术后 1～ 5 d抽血测定血清 AL T、AST含量 ,数据均经统计学处理。结果　电切组术后 1 d血清AL T、AST水平显著升高 ,与术前相比 ,差异有显著性 (P<0 .0 1 ) ,与剪切组术后相比 ,差异有显著性 (P<0 .0 1 )。肝组织病理变化 ,电切组浅层 (电刀接触面 )肝细胞大部分热溶解坏死 ,其内层肝血窦扩散 ,肝细胞膜皱缩 ,深层 (1 cm )肝细胞变性水肿 ,剪切组肝细胞正常。结论　 L C术中单极高频电刀在密闭腔内对局部肝组织的热损伤是引起肝细胞坏死、皱缩、水肿等不同程度的病理变化 ,深度可达 1 cm ,是术后血清 AL T、AST一过性升高的主要原因     

高脂饮食性非酒精性脂肪性肝病大鼠肝脏PPAR-γ表达增强

目的探讨过氧化物酶体增值物活化受体γ(PPAR-γ)及其亚型在高脂饮食所致非酒精性脂肪性肝病(NAFLD)大鼠肝脏的表达及其意义.方法模型组SD大鼠给予高脂肪高胆固醇饮食饲养,分批于实验第8、12、26、24周处死,同期设普通饮食饲养大鼠作对照.免疫组织化学和RT-PCR分别检测大鼠肝脏PPAR-γ的表达.结果模型组大鼠第8周呈现单纯性脂肪肝,第12～24周从脂肪性肝炎进展为脂肪性肝炎伴肝纤维化.免疫组织化学和RT-PCR显示,随着造模时间延长,肝脏PPAR-γ的表达逐渐增强.模型组肝脏PPAR-γ1 mRNA表达于第24周达到高峰(与对照组相比升高3.5倍,P＜0.01),PPAR-γ2 mRNA表达于造模第16周时达高峰(较对照组升高5.8倍,P＜0.01).相关分析显示,仅PPAR-γ2 mRNA与肝脂变程度之间关系密切(r=0.89,P＜0.05).结论持续24周的高脂饮食可以成功复制大鼠NAFLD模型,模型大鼠肝脏PPAR-γ表达增强,NAFLD大鼠肝细胞可能部分具有脂肪细胞的特征,即脂肪变的肝细胞发生成脂性改变.     

高脂饮食诱导小鼠脂肪肝

目的 初步探索高脂饮食对小鼠肝脏的损伤情况.方法 40只小鼠随机分为2组,实验组给予高脂饮食,对照组正常饮食.1个月后,采用颈椎处死法,将取出的肝脏进行病理学观察以及肝脂的测定.结果 实验组和对照组相比,肝重、肝重/体重、肝脂、肝脏大体标本和肝脏病理组织学观察差异在统计学上均具有显著性意义.结论 高脂饮食可能在小鼠脂肪肝的发生中起到一定的作用,但有必要开展各种不同类饮食的混合喂养以及剂量反应关系的研究.     

质子磁共振波谱测定大鼠椎体脂肪含量的可行性研究

目的探讨临床商用3.0 T磁共振扫描仪对大鼠椎体行质子磁共振波谱(proton magnetic resonance spectroscopy,~1H-MRS)检查评估骨髓脂肪含量的可行性。方法 15只3月龄正常雌性SD大鼠以及5只骨质疏松模型SD大鼠(去卵巢法)行多体素点分辨波谱法检查测定腰5椎体脂肪分数(fat fraction,FF),分析两名放射科医师测量正常大鼠腰5椎体FF值的一致性,并观察正常和骨质疏松模型大鼠的波谱以及病理特点。结果两名放射科医师测得的正常大鼠腰5椎体FF值分别为(10.92±3.31)%、(11.10±3.20)%,组内相关系数为0.954。~1H-MRS显示水峰明显高于饱和脂肪酸主峰(长链亚甲基质子),而不饱和脂肪酸峰烯烃质子和亚甲基质子(与烯烃质子相连)未见明确显示,HE染色显示骨髓内脂肪细胞少见,散在分布,体积较小;骨质疏松模型大鼠腰5椎体的FF值为(20.13±4.20)%,~1H-MRS显示水峰明显高于饱和脂肪酸主峰(长链亚甲基质子),但饱和脂肪酸主峰有所升高,不饱和脂肪酸峰烯烃质子和亚甲基质子(与烯烃质子相连)明确显示,信号振幅较小,HE染色显示骨髓内脂肪细胞增多,弥漫分布,体积增大。结论临床商用3.0 T磁共振扫描仪行~1H-MRS检查测定FF值评估大鼠椎体骨髓脂肪含量具备可行性。     

高能聚焦超声治疗后兔肝VX2种植瘤1H-MRS成像特点

目的研究高能聚焦超声（HIFU）治疗后的兔肝VX2种植瘤氢质子磁共振波谱（1H—MRS）的谱图特点及变化规律。方法建立20只新西兰大白兔肝VX2肿瘤模型,对其行HIFU治疗,分别于治疗前、后行常规MR平扫和二维多体素1H～MRS检查,每只兔均选取瘤体中央区、周边区及瘤周正常肝组织作为感兴趣区（ROI）,比较HIFU治疗前、后相同ROI的Cho／Cr及Lip／Cr。结果20只兔肝VX2模型治疗前、后共获得28瘤次可纳入统计学分析的1H—MRS图。典型的1H—MRS图上可见6个主要的波峰,包括脂质（Lip）、谷氨酰胺和谷氨酸复合物（Glx）、胆碱（Cho）、乳酸（Lac）和肌酸（Cr）。治疗后肿瘤中央区、周边区内Cho峰和Lac峰均较治疗前升高,Lip峰治疗后较治疗前降低;瘤周正常肝组织治疗前、后各主要代谢物变化不明显。治疗前后肿瘤中央区及周边区Cho／Cr、Lip／Cr值差异有统计学意义（P〈0．05）。结论二维多体素,H—MRS能反映VX2种植瘤经HIFU治疗后不同ROI主要代谢物水平变化。     

(201)Tl-SPECT, (1)H-MRS, and MIB-1 labeling index of central neurocytomas: three case reports

BACKGROUND: The proliferative activity and metabolic features of three central neurocytomas were investigated using the findings of thallium-201 single photon emission computed tomography ((201)Tl-SPECT) and proton magnetic resonance spectroscopy ((1)H-MRS), and the MIB-1 labeling index (MIB-1 LI). METHOD: The early and delayed (201)Tl indices were calculated as the ratio of tumour to normal brain tissue uptake by (201)Tl-SPECT. In vivo single-voxel (1)H-MRS was performed with echo time of 272 msec to evaluate the metabolites including choline (Cho), N-acetyl aspartate (NAA) and creatine/phosphocreatine (Cre). An external standard reference was used to semiquantitate each metabolite. MIB-1 LI was determined in the surgical specimens. FINDINGS: The MIB-1 LI was 0.5%, 1.2%, and 7.5% in an atypical central neurocytoma without intraventricular extension. Significant (201)Tl uptake was observed on delayed images in all three central neurocytomas. (1)H-MRS showed the high Cho peaks relative to the NAA and Cre peak. The signal at 3.55 ppm, which may be due to inositol or glycine, was observed in one central neurocytoma. INTERPRETATION: Both (201)Tl-SPECT and (1)H-MRS did not reflect the proliferative potential of central neurocytomas.     

201Tl-SPECT and 1H-MRS study of benign lateral ventricle tumors: differential diagnosis of subependymoma

The introduction of computed tomography (CT) and magnetic resonance (MR) imaging has resulted in the detection of increasing numbers of asymptomatic intraventricular tumors. Establishing the correct preoperative diagnosis is important to prevent unnecessary surgical intervention. Our study includes nine cases of benign lateral ventricle tumors including two cases of central neurocytoma, two of subependymal giant cell astrocytoma, two of pilocytic astrocytoma and three of subependymoma treated surgically between 1996 and 2003. MR imaging, proton MR spectroscopy (¹H-MRS) and thallium-201 single photon emission computed tomography (²⁰¹Tl-SPECT) were performed in all patients. All three types of tumor demonstrated heterogeneous enhancement on MR imaging with gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) and increased choline (Cho) peak and decreased N-acetyl aspartate (NAA) and creatine (Cre) peaks on ¹H-MRS. ²⁰¹Tl-SPECT showed high uptake of ²⁰¹Tl without wash out in all cases of central neurocytoma, subependymal giant cell astrocytoma and pilocytic astrocytoma, but no uptake in cases of subependymoma. Absence of ²⁰¹Tl uptake in contrast with enhancement on MR imaging and the ¹H-MRS features of modest elevation of the Cho/Cre ratio, reduction of the NAA peak and presence of lactate/lipid peaks are characteristic features of subependymomas and useful to establish a preoperative diagnosis.     

Brain abscess and glioblastoma identified by combined proton magnetic resonance spectroscopy and diffusion-weighted magnetic resonance imaging--two case reports

The differential diagnosis between brain abscesses and necrotic tumors such as glioblastomas is sometimes difficult to establish by conventional computed tomography and magnetic resonance imaging. Combined proton magnetic resonance spectroscopy (1H-MRS) and diffusion-weighted magnetic resonance imaging (DWI) were used to establish the preoperative diagnosis of brain abscess and glioblastoma. DWI visualized the brain abscess as a homogeneous hyperintense lesion and 1H-MRS revealed the presence of acetate, lactate, and amino acids and the absence of the normal brain components. DWI sometimes shows glioblastoma as a hyperintense lesion, but 1H-MRS reveals markedly increased lactate and decreased N-acetyl-aspartate. Combined DWI and 1H-MRS findings can distinguish brain abscess and glioblastoma.     

Changes in 1H-MRS in glioma patients before and after irradiation: the significance of quantitative analysis of choline-containing compounds

The evaluation of the response to radiation therapy in brain tumor patients is a major and an important issue. Although CT and MRI can measure changes in tumor size, it is difficult to use these imaging methods to evaluate the viability or the proliferation activity of a tumor. In this study, we investigated the metabolite changes in glioma patients using 1H-MRS from before to after radiation therapy, to see whether or not early metabolic changes occur during therapy. Seven patients with histologically proven glioma (1 astrocytoma, 1 anaplastic astrocytoma, 2 oligoastrocytoma, 1 oligodendroglioma, 2 glioblastoma) were examined by means of 1H-MRS using a point-resolved spectroscopy (PRESS) sequence with a repetition time of 2,000 ms and echo times of 68 ms, 136 ms and 272 ms. The 1H-MRS was evaluated by both the spectrum pattern and the quantification of the metabolites. As to radiation therapy, each patient received a total dose of 64.8 Gy (1.8 Gy/fraction) with a 10-MeV linear accelerator. The results revealed that the concentration of choline-containing compounds (Cho) was 4.55 +/- 1.08 mmol/kg wet weight before radiation therapy and was reduced to 2.69 +/- 0.56 mmol/kg wet weight (p < 0.01) after radiation therapy. Moreover, both the N-acetylaspartate (NAA) peak and creatine/phosphocreatine (t-Cr) peak were lower after radiation therapy than before. The peaks of both the lipids (Lip) and lactate (Lac) were higher after radiation therapy than before. In conclusion, Cho concentration is thought to be a useful marker for the evaluation of early post-radiation response. The effect of radiation therapy can be evaluated according to the value of Cho. Further long-term MRS study is needed to prove whether or not the decrease of the Cho value in the present study will change before recurrence at later stages.     

201Tl-SPECT, 1H-MRS, and MIB-1 Labeling Index of Central Neurocytomas: Three Case Reports

Summary. Summary.   Background: The proliferative activity and metabolic features of three central neurocytomas were investigated using the findings of thallium-201 single photon emission computed tomography (²⁰¹Tl-SPECT) and proton magnetic resonance spectroscopy (¹H-MRS), and the MIB-1 labeling index (MIB-1 LI).   Method: The early and delayed ²⁰¹Tl indixes were calculated as the ratio of tumour to normal brain tissue uptake by ²⁰¹Tl-SPECT. In vivo single-voxel ¹H-MRS was performed with echo time of 272 msec to evaluate the metabolites including choline (Cho), N-acetyl aspartate (NAA) and creatine/phosphocreatine (Cre). An external standard reference was used to semiquantitate each metabolite. MIB-1 LI was determined in the surgical specimens.   Findings: The MIB-1 LI was 0.5%, 1.2%, and 7.5% in an atypical central neurocytoma without intraventricular extension. Significant ²⁰¹Tl uptake was observed on delayed images in all three central neurocytomas. ¹H-MRS showed the high Cho peaks relative to the NAA and Cre peak. The signal at 3.55 ppm, which may be due to inositol or glycine, was observed in one central neurocytoma.   Interpretation . Both ²⁰¹Tl-SPECT and ¹H-MRS did not reflect the proliferative potential of central neurocytomas.     

Metabolic characteristics of intracranial metastases, detected by single-voxel proton magnetic resonance spectroscopy, are seemingly not predictive for tumor response to gamma knife radiosurgery.

Metabolic characteristics of intracranial metastases, detected with proton magnetic resonance spectroscopy (1H-MRS) have known associations with clinical predictors of tumor response to radiosurgery. Therefore, it can be suspected that the metabolic profile of the neoplasm by itself might have some prognostic significance for the outcome after irradiation. Twenty-six intracranial metastases, which underwent metabolic evaluation with single-voxel 1H-MRS before gamma knife radiosurgery (GKR) and were followed for at least 3 months after treatment, were selected for retrospective analysis. The tumors most frequently originated from the lungs (9 cases), breast (7 cases), colon and rectum (5 cases). The average volume of the investigated intracranial neoplasm was 5.4+/-2.0 mL. The average marginal irradiation dose was 18.6+/-2.3 Gy. The mean follow-up after GKR constituted 8.0+/-5.5 months. Tumor response to GKR was identified in 13 cases on average 2.2+/-1.8 months after treatment. Local recurrence was marked in 10 cases on average 8.7+/-4.1 months after treatment. None of the investigated 1H-MRS metabolic parameters of intracranial metastases showed a statistically significant association with the outcome after GKR. The negative results of the present study make doubtful the predictive value of metabolic characteristics of intracranial metastases, detected with single-voxel 1H-MRS, for the outcome after radiosurgery.