囊性脑转移瘤的MR诊断及鉴别诊断

目的探讨囊性脑转移瘤的MR诊断及鉴别诊断。方法回顾性分析经手术病理或临床证实的15例囊性脑转移瘤患者的MR平扫、增强、DWI及ADC图表现。结果15例共22个囊性转移灶,囊壁在T1WI、T2WI呈等或低信号,囊液T1WI信号稍高于脑脊液,T2WI信号亦高于脑脊液;增强扫描肿瘤呈环形强化,部分病灶可见强化壁结节;DWI图呈低信号,ADC图呈高信号,平均ADC值为（1.87±0.24）×10-3mm2/s。结论囊性脑转移瘤DWI图、ADC图、囊内信号、囊壁增强的MR表现有助于其诊断和鉴别诊断。     

3．0T磁共振背景抑制弥散加权成像对直肠癌淋巴结转移的诊断价值

目的评估3．0T磁共振背景抑制弥散加权成像（DWIBS）对直肠癌转移性淋巴结的诊断价值。方法35例直肠癌患者术前行常规MRI加弥散加权成像（DWI）检查．手术行直肠癌切除加淋巴结清扫术。对照术后病理结果,确定转移性和非转移性淋巴结,测量淋巴结的表观弥散系数（ADC）值以及长、短径,并绘制受试者工作特征（ROC）曲线来评估淋巴结ADC值及长、短径对转移性淋巴结的鉴别诊断价值。结果35例直肠癌患者共获取部位明确的淋巴结151枚．其中转移性淋巴结65枚,非转移性淋巴结86枚。其ADC值分别为[（0．86±0．14）×10^-3]和[（0．94±0．16）×10^-3]mm^2／s,长径分别为（9．78±3．13）和（7．90±1．77）mm,短径分别为（7．65±2．00）和（6．45±1．19）mm,两者比较差异均有统计学意义（均P〈0．01）。ADC值、淋巴结长径、短径判断淋巴结是否转移的ROC曲线下面积分别为0．648、0．706、0．692,取最佳分界值[分别为（1．05×10^-3]mm^2／s、7．95mm、5．90mm]．三者的敏感性和特异性分别为93．8％和30．2％、75．4％和61．6％、90．8％和38．4％。结论3．0T磁共振DWIBS的ADC值的定量测量能够反映病灶的弥散受限程度．直肠癌转移性淋巴结的诊断需要ADC值、淋巴结径线测量的综合评价。     

MRI对腹膜后良性神经源性肿瘤的诊断价值

目的 探讨MRI常规T1WI、T2WI、弥散加权成像（DWI）结合增强扫描对腹膜后良性神经源性肿瘤的诊断价值。方法 回顾性研究34例腹膜后良性神经源性肿瘤的MRI常规T1WI、T2WI、DWI及增强表现,所有病变均经手术病理证实,包括神经鞘瘤15例,副神经节瘤11例,节细胞瘤8例。结果 神经鞘瘤、副神经节瘤、节细胞瘤患者发病年龄、肿瘤大小无统计学差异（P>0.05）,均易产生囊变,神经鞘瘤囊变多位于病灶中心,副神经节瘤囊变多位于病灶周边,神经鞘瘤出血明显多于其他两者（P<0.05）,神经鞘瘤及副神经节瘤呈类圆形或椭圆形,节细胞瘤在形态上呈不规则形;三种病例在DWI上均呈稍高信号,部分囊变出血呈混杂信号,DWI信号强度及ADC值差异无统计学意义（P>0.05）。副神经节瘤强化最明显,神经鞘瘤其次,节细胞瘤轻度强化。结论 MRI增强扫描对腹膜后良性神经源性肿瘤的鉴别诊断具有重要作用,常规T2WI及T1WI对病灶形态、大小显示较好,T2WI对显示囊变、T1WI对显示出血具有优势,DWI鉴别价值不高。     

3.0T MRI扩散加权成像在鉴别肝脏转移瘤与肝内胆管细胞癌中的价值

目的:分析研究扩散加权成像在鉴别肝脏转移瘤和肝内胆管细胞癌中的价值。方法:回顾性分析病理证实的肝脏转移瘤患者和肝内胆管细胞癌患者的MRI原始资料,包括DWI序列和常规MRI平扫序列(包括T1WI和T2WI)。两种病例各14例,测得其表观扩散系数(ADC)值、瘤/肝值,以及肿瘤与邻近肝实质之间的差异,并进行比较。结果:受检28例患者共28个肿瘤,所有肿瘤在ADC图上均呈现高信号,T2WI呈现稍高信号,T1WI呈现稍低信号,边界较为清楚。肝脏转移瘤平均ADC值为0.943±0.132,肝内胆管细胞癌平均ADC值为1.001±0.008,两者差异无统计学意义(t=0.695,P0.05)。肝脏转移瘤的瘤/肝值显著低于肝内胆管细胞癌(t=2.780,P0.05)。肝脏转移瘤和肝内胆管细胞癌的ADC值均低于邻近肝实质(t=6.143、8.545,P0.05)。结论:磁共振DWI序列中测得的瘤/肝值能够对肝内转移瘤和肝内胆管细胞癌的鉴别诊断提供有价值的信息。     

脑转移瘤的磁共振序列优化

目的探讨MR常规序列及T1加权三维成像(3D-T1WI)诊断脑转移瘤的价值,优化脑转移瘤MR扫描方案。方法收集原发灶经病理证实的35例脑转移瘤患者,均行MR常规序列及3D-T1WI平扫和增强扫描,分析各序列对脑转移瘤的检出率,并对比常规扫描方案与优化扫描方案的扫描时间。结果 35例共检出609个病灶;平扫T1WI、T2WI、T2-FLAIR、DWI(b=0)、3D-T1WI分别检出病灶101个(101/609,16.58%)、155个(155/609,25.45%)、235个(235/609,38.59%)、176个(176/609,28.90%)、228个(228/609,37.44%);增强T1WI、3D-T1WI分别检出病灶427个(427/609,70.11%)、609个(609/609,100%)。增强及平扫3D-T1WI对脑转移瘤的检出率明显高于增强及平扫T1WI(P均0.05);DWI(b=0)与T2WI对脑转移瘤检出率差异无统计学意义(P0.05)。常规方案MR扫描共用时638s,优化方案为575s。结论 3D-T1WI序列可明显提高MR对脑转移瘤的检出率。以3D-T1WI替代常规T1WI、DWI(b=0)替代T2WI的优化扫描方案可提高脑转移瘤检出率,缩短扫描时间。     

3.0 T MR弥散加权成像对鉴别胰腺癌与慢性肿块型胰腺炎的价值

目的探讨在3．0T磁共振（MR）平台上应用弥散加权成像（diffusion—weighted imaging，DWI）鉴别诊断胰腺癌与慢性肿块型胰腺炎的价值。方法纳入经手术病理和临床随访证实的胰腺癌患者13例、慢性肿块型胰腺炎患者7例和健康志愿者14例，在行上腹部常规MR扫描后进行胰腺DWI检查。采用自旋回波回波平面成像技术和空间敏感性编码技术，分别取弥散梯度b值=400、600、800和1000s／mm^2获得相应的DWI图像，测量感兴趣区（ROI）的ADC值，并进行统计学分析。结果①健康志愿者胰腺DWI呈中等信号。②胰腺癌患者癌组织在DWI上呈均匀高信号，边界较清楚；各b值（400、600、800和1000s／mm^2）下，测得ADC值分别为（1．63&#177;0．235）、（1．42&#177;0．126）、（1．36&#177;0．170）及（1．26&#177;0．178）&#215;10^-3mm^2／s，明显低于癌周胰腺组织[（2．11&#177;0．444）、（1．83&#177;0．230）、（1．81&#177;0．426）及（1．60&#177;0．230）&#215;10^-3mm^2／s]及健康志愿者胰腺的ADC值[（1．85&#177;0．350）、（1．69&#177;0．290）、（1．67&#177;0．268）及（1．42&#177;0．221）&#215;10^-3mm^2／s]，P〈0．05。③慢性肿块型胰腺炎在DWI上呈不均匀稍高信号，边界不清；各b值下测得ADC值分别为（1．69&#177;0．150）、（1．56&#177;0．119）、（1．59&#177;0．172）及（1．35&#177;0．080）&#215;10^-3mm^2／s，均高于胰腺癌组织的ADC值，但仅当b值-800s／mm^2时，与胰腺癌组织间差异有统计学意义（P〈0．05）。结论DWI可以清楚显示胰腺肿瘤病灶及范围，结合ADC的测量值能够为鉴别胰腺癌与慢性肿块型胰腺炎提供一定的信息。     

3.0T磁共振扩散加权成像诊断肾血管 平滑肌脂肪瘤

目的探讨MR扩散加权成像（DWI）及相应的表观扩散系数（ADC）对肾血管平滑肌脂肪瘤（AML）的诊断价值。方法收集经手术病理证实的肾脏AML患者15例,其中典型AML 10例,不典型AML 5例;正常对照组15名,对病变区域行DWI及常规MRI,测量b=50～1000 s/mm^2时肾脏AML及正常对照组的ADC值。结果肾脏典型AML、不典型AML及正常对照组的ADC值（×10^-3mm^2/s）分别为（0.87±0.08）、（1.55±0.34）、（1.82±0.18）,差异有统计学意义（P〈0.05）。结论3.0T磁共振DWI及ADC值测定可为诊断肾脏AML提供帮助。     

磁共振扩散加权成像在胰腺癌诊断中的应用

目的 探讨磁共振扩散加权成像(DWl)及相应的表观扩散系数(ADC)在胰腺癌诊断中的应用价值.方法 回顾性分析2009年3月至2011年6月无锡市第二人民医院收治的36例胰腺癌患者和30例健康志愿者的临床资料.66例受试者接受MRI检查,进行DWI扫描.胰腺癌患者的肿瘤组织和癌周组织在T1WI、T2WI及DWI图像中的信号强度比(SIR)的比较采用单因素方差分析;肿瘤组织与癌周组织的ADC值比较采用配对t检验;肿瘤组织、癌周组织分别与健康志愿者胰腺组织的ADC值比较采用独立样本t检验.结果 胰腺癌患者术前MRI检查诊断的准确性达到92％.T2WT、T1WI及DWI图像中,胰腺癌患者的SIR分别为0.203±0.190、0.399±0.201及0.579±0.291,肿瘤组织和癌周组织的信号强度在3组图像间比较,差异有统计学意义(F=5.92,6.15,6.83,P＜0.05);患者在T1WI和DWI图像中的SIR均明显高于T2WI图像(P＜0.05),而T1WI与DWI图像SIR比较,差异无统计学意义(P＞0.05).测量患者肿瘤组织、癌周组织、健康志愿者胰腺组织的平均ADC值分别为(1.40 ±0.24)×10-3 mm2/s、(1.71±0.10) ×10-3 mm2/s、(1.73 ±0.30) ×10-3mm2/s,肿瘤组织与癌周组织、肿瘤组织与胰腺组织的ADC值比较,差异有统计学意义(t=10.54,12.08,P＜0.05).结论 DWI图像可以清晰地显示胰腺癌病灶,ADC值的测定有助于胰腺癌的诊断.     

脊椎转移瘤的M砌诊断

目的同顾性分析脊椎转移瘤的MRI诊断特征及规律。方法本组20例患者,男16列、女4例,均先行MRI平扫,其中2例加增强扫描、2例加脂肪抑制序列扫描。结果胸椎受累8例,腰椎受累6例,颈椎受累1例,胸腰椎同时受累4例,颈胸椎同时受累1例;T1WI呈低信号14例,呈等信号6例;T2WI呈高信号12例,呈等信号6例,呈低信号2例。结论MRI对脊椎转移瘤的检出具有高度的敏感性;脊椎转移瘤多呈多发性、跳跃分布;脊椎转移瘤T1WI上多呈低信号或等信号,T2WI上信号不定,脂肪抑制序列呈高信号。     

磁共振扩散加权成像检查对前列腺癌新辅助内分泌治疗疗效的预测价值

目的探讨磁共振扩散加权成像(DWI)检查对前列腺癌新辅助内分泌治疗疗效程度的预测价值。方法回顾性分析2016年1月至2019年9月北京大学第一医院收治的33例前列腺癌患者的病例资料。年龄平均67.7(49~81)岁。内分泌治疗前PSA平均36.8(7.5~126.5)ng/ml。33例均行前列腺MRI检查,其中30例于穿刺前平均18(2~33)d进行检查,3例于穿刺后平均35(20~44)d进行检查。扫描序列包括轴位和矢状位T1WI正反相位、冠状位T2WI压脂、轴位T1WI、轴位T2WI、轴位DWI及动态对比增强(DCE)序列。新辅助内分泌治疗前前列腺体积平均57.41(17.84~270.74)cm……3。由2名影像科医生根据前列腺影像报告和数据系统(PI-RADS)标准阅片,将PI-RADS 4~5分定义为前列腺癌灶。测量表观扩散系数(ADC)值。内分泌治疗前,患者正常外周带、移行带ADC值分别为(1.638±0.328)×10^-3mm^2/s、(1.335±0.249)×10^-3mm^2/s,癌灶ADC值为(0.828±0.291)×10^-3mm^2/s。所有患者均行经直肠超声引导下系统穿刺,病理诊断均为前列腺癌。Gleason评分:3+3分5例,3+4分4例,4+3分6例,3+5分1例,4+4分6例,4+5分8例,5+4分2例,5+5分1例。根据国际泌尿病理协会(ISUP)分级分组标准:1级(Gleason评分≤3+3=6分)5例,2级(Gleason评分3+4=7分)4例,3级(Gleason评分4+3=7分)6例,4级(Gleason评分4+4=8分、3+5=8分、5+3=8分)7例,5级(Gleason评分5+4=9分、4+5=9分、5+5=10分)11例。ISUP 1~3级为中低危组(15例),ISUP 4~5级为高危组(18例)。穿刺活检后行新辅助内分泌治疗,22例应用戈舍瑞林联合比卡鲁胺,9例应用曲普瑞林联合比卡鲁胺,2例应用亮丙瑞林联合比卡鲁胺。内分泌治疗时间平均7.2(5~13)个月。所有患者内分泌治疗后行根治性前列腺切除术。记录患者新辅助内分泌治疗后的ADC变化值和ADC变化率。比较ISUP中低危组和高危组的ADC变化值和ADC变化率,以及不同治疗反应程度患者的ADC变化值和ADC变化率。绘制受试者工作特征(ROC)曲线,分析ADC变化率预测前列腺癌新辅助内分泌治疗反应程度的价值。结果本研究33例,新辅助内分泌治疗后的前列腺体积平均28.50(6.25~113.76)cm3,与治疗前比较差异有统计学意义(Z=-4.458,P<0.05);治疗后(根治术前)PSA平均0.721(0~5.23)ng/ml,与治疗前比较差异有统计学意义(Z=-5.012,P<0.05)。治疗后ADC值分别为正常外周带(1.197±0.265)×10^-3mm^2/s(P<0.05),正常移行带(1.206±0.222)×10^-3mm^2/s(P=0.016),癌灶(1.070±0.325)×10^-3mm^2/s(P<0.05),与治疗前比较差异均有统计学意义。癌灶ADC值升高与PSA值下降无明显相关性(相关系数为0.169,P=0.382)。ISUP中低危组和高危组的ADC变化值分别为(0.315±0.173)×10^-3mm^2/s和(0.164±0.224)×10^-3mm^2/s,差异有统计学意义(P=0.047);ADC值变化率分别为(42.6±27.2)%和(23.8±29.9)%,差异无统计学意义(P=0.083)。本组33例均对内分泌治疗有反应,根治术后病理表现包括:无肿瘤细胞残留;肿瘤细胞萎缩伴空泡变性,细胞核固缩,部分产生黏液变性,部分病例可见泡沫细胞聚集;正常前列腺组织腺体萎缩,基底细胞增生。治疗明显反应组和局灶反应组的ADC变化值分别为(0.278±0.218)×10^-3mm^2/s和(0.094±0.119)×10^-3mm^2/s,差异有统计学意义(P=0.010);ADC变化率分别为(39.0±30.0)%和(11.4±17.0)%,差异有统计学意义(P=0.006)。ADC变化率预测前列腺癌新辅助内分泌治疗反应的ROC曲线下面积为0.795(P=0.02)。ADC变化率取最佳界值19.7%时,预测敏感性和特异性分别为73.9%和85.7%。结论前列腺癌患者行新辅助内分泌治疗后MRI检查的ADC值具有显著变化,且变化数值与治疗反应程度相关。DWI可以作为前列腺癌新辅助内分泌治疗效果的评估手段,并能预测治疗反应的程度。     

弥散张量成像鉴别诊断肾透明细胞癌与肾盂移行细胞癌

目的评价MRI弥散张量成像(DTI)在肾透明细胞癌(ccRCC)与肾盂移行细胞癌(TCC)鉴别诊断中的价值。方法回顾性分析行腹部MR检查、经病理证实为ccRCC及TCC的患者38例(ccRCC 29例,TCC 9例)。患者均行MR T1W脂肪抑制和T2W脂肪抑制序列扫描、LAVA增强扫描、DTI序列扫描(b=0、600s/mm~2)。由2名放射科医师采用AW 4.4工作站采用Functool后处理软件进行图像分析和测量。采用组内相关系数(ICC)检验2名察者所测数据的一致性。ccRCC和TCC ADC值及FA值的比较采用独立样本t检验。采用ROC曲线分析ADC值、FA值对ccRCC与TCC的鉴别诊断效能。结果 2名观察者测量各参数一致性良好(ICC值均0.75)。ccRCC的ADC值[(2.03±0.49)×10~(-3) mm~2/s]高于TCC[(1.57±0.43)×10~(-3 )mm~2/s;P=0.015)],但ccRCC的FA值(0.24±0.10)低于TCC(0.42±0.22);P=0.002)。ADC值曲线下面积0.761(P0.05),敏感度和特异度分别为79.3%、77.8%,阈值为1.59×10~(-3) mm~2/s。FA值曲线下面积为0.762(P0.05),敏感度和特异度分别为66.7%、93.1%,阈值为0.326。结论 MR DTI可有效鉴别ccRCC和肾盂TCC,其中FA值对鉴别两者的特异度较高。     

肝细胞癌冷冻治疗术后完全消融早期MRI特征

目的探讨氩氦刀冷冻治疗肝细胞癌(HCC)术后完全消融的MRI表现。方法回顾性分析经随访证实氩氦刀冷冻治疗消融完全的48例HCC患者术前及术后2~7天MRI资料,测量冷冻治疗前后病灶及其周围肝实质ADC值。结果消融后,38例T1WI呈高信号,26例T2WI呈低信号;增强扫描动脉期瘤结节均未见强化,但9例瘤结节出现门静脉晚期及延迟期强化;消融区周边均可见环形强化,25例可见消融区相邻肝包膜下斑片状强化;30例可见瘤结节周边消融区肝实质内穿行小血管强化,7例可见周围肝实质强化。冷冻治疗前后肿瘤ADC值分别为(0.80±0.33)×10-3 mm2/s、(1.26±0.54)×10-3 mm2/s,差异有统计学意义(P0.01)。结论 MRI可用于评价氩氦刀治疗肝癌的早期疗效,冷冻消融后肿瘤及周围肝实质延迟持续强化并不一定代表肿瘤残留,术后ADC值的变化可用于预测早期疗效。     

Assessment of therapeutic response in patients with brain abscess using diffusion tensor imaging

BackgroundAccurate assessment of therapeutic response in patients with brain abscess (BA) is essential to direct appropriate therapy. This study was performed with an aim to see the treatment-induced changes in diffusion tensor imaging (DTI) indices (ie, fractional anisotropy [FA] and mean diffusivity [MD]) in follow-up patients with BA after treatment.MethodsTwenty patients with BA were prospectively studied in this study. Diffusion tensor imaging in first follow-up was done in all after 1 week and in 6 at 4 weeks of the initial study.ResultsThe mean FA and MD values in first, second, and third studies were 0.28 ± 0.03 and (0.81 ± 0.07) × 10^?3 mm²/s, 0.18 ± 0.09 and (1.08 ± 0.09) × 10^?3 mm²/s, and 0.13 ± 0.04 and (0.99 ± 0.13) × 10^?3 mm²/s, respectively. The FA value was significantly (P < .01) decreased along with no significant change in MD value (P = .08) for 3 study periods. The mean volume (in milliliter) of the abscesses was 2.14 ± 1.04, 1.34 ± 0.45, and 0.77 ± 0.14 in first, second, and third studies, respectively.ConclusionsWe conclude that the reduction in FA value reflects the down-regulation of the neuroinflammatory molecules in response to treatment in patient with BA and may be used to assess therapeutic response in these patients in future.     

扩散张量成像诊断兔急性缺血性骨骼肌溶解

目的探讨DTI在诊断兔急性缺血性骨骼肌溶解中的价值。方法将26只新西兰大白兔一侧后肢供血动脉及侧支血管结扎,建立后肢急性缺血模型(骨骼肌溶解组);以对侧作为对照组。于术后8h对两侧后肢进行T2WI及DTI,测量外侧肌肉ADC值及FA值,留取相应部位肌肉组织进行透射电镜检查。结果于26只兔均成功建立后肢骨骼肌缺血模型。血管结扎后8h骨骼肌溶解组肌肉T2WI信号增高;ADC值为(1.26±0.25)×10-9 m2/s,高于对照组[(0.98±0.38)×10-9 m2/s,P<0.05],FA值为0.16±0.03,低于对照组(0.28±0.05,P<0.05);透射电镜示骨骼肌溶解组骨骼肌出现溶解。结论 DTI可诊断骨骼肌缺血后坏死和溶解,具有重要临床应用价值。     

磁共振扩散张量成像与纤维束成像在脊髓型颈椎病中的应用研究

目的 :评价磁共振扩散张量成像技术(diffusion tensor imaging,DTI)对脊髓型颈椎病的诊断价值。方法 :对收集的2014年1月至2015年4月20例健康志愿者和50例脊髓型颈椎病(CSM)患者行颈髓DTI。以健康志愿者作为对照组。依据颈髓MRI平扫结果将CSM患者分A、B、C组,A组17例(单纯硬膜囊受压),B组23例(颈髓受压,信号正常),C组10例(颈髓受压,T2高信号)。分析4组颈髓的平均表观扩散系数(ADC)、平均分数各向异性值(FA)之间的差异,对所有受检者行颈髓纤维束成像。结果:对照组C_2/C_3、C_3/C_4、C_4/C_5、C_5/C_6、C_6/C_7之间ADC值及FA值差异无统计学意义(P0.05),平均ADC值为(0.875±0.096)×10~(-3)mm~2/s,平均FA值为0.720±0.051;对照组与A组比较,平均ADC值、FA值差异无统计学意义,对照组与B、C组及A、B、C组间比较,平均ADC值、FA值差异均有统计学意义。结论:颈髓DTI较常规MRI能够早期、准确地量化脊髓型颈椎病的颈髓微结构改变,颈髓纤维束成像可以反映脊髓纤维束受压损伤的范围。     

Diffusion tensor imaging in the cervical spinal cord

There are discrepancy between MR findings and clinical presentations. The compressed cervical cord in patients of the spondylotic myelopathy may be normal on conventional MRI when it is at the earlier stage or even if patients had severe symptoms. Therefore, it is necessary to take a developed MR technique—diffusion tensor imaging (DTI)—to detect the intramedullary lesions. Prospective MR and DTI were performed in 53 patients with cervical compressive myelopathy and twenty healthy volunteers. DTI was performed along six non-collinear directions with single-shot spin echo echo-planar imaging (EPI) sequence. Intramedullary apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in four segments (C2/3, C3/4, C4/5, C5/6) for volunteers, in lesions (or the compressed cord) and normal cord for patients. DTI original images were processed to produce color DTI maps. In the volunteers’ group, cervical cord exhibited blue on the color DTI map. FA values between four segments had a significant difference (P < 0.01), with the highest FA value (0.85 ± 0.03) at C2/3 level. However, ADC value between them had no significant difference (P > 0.05). For patients, only 24 cases showed hyperintense on T2-weighted image, while 39 cases shown patchy green signal on color DTI maps. ADC and FA values between lesions or the compressed cord and normal spinal cord of patients had a significant difference (both P < 0.01). FA value at C2/3 cord is the highest of other segments and it gradually decreases towards the caudal direction. Using single-shot spin echo EPI sequence and six non-collinear diffusion directions with b value of 400 s mm⁻², DTI can clearly show the intramedullary microstructure and more lesions than conventional MRI.     

原发性中枢神经系统淋巴瘤常规及功能磁共振成像特点

目的探讨原发性中枢神经系统淋巴瘤(PCNSL)常规MRI及fMRI特点。方法回顾性分析21例经病理证实的PCNSL的常规MRI及DWI、1 H-MRS、PWI表现。结果 21例患者共39个PCNSL病灶的ADC值为(0.78±0.14)×10-3 mm2/s,对侧半球正常脑白质ADC值为(0.89±0.21)×10-3 mm2/s,二者差异有统计学意义(t=1.24,P0.05)。相对于正常脑白质,PCNSL病灶1 H-MRS波谱表现为Cho/Cr值增高(4.62±2.05vs 0.83±0.25)、Cho/NAA值增高(6.86±2.36vs 0.63±0.34)、NAA/Cr值减低(0.67±1.73vs 0.63±.034),差异均有统计学意义(P均0.05)。PCNSL病灶PWI表现为相对低灌注,脑血容量低于周围正常脑实质。结论采用MR DWI、1 H-MRS、PWI可从不同方面反映PCNSL的特征,结合常规MRI征象可进一步提高诊断准确率。     

Differential diagnosis of the small renal masses: role of the apparent diffusion coefficient of the diffusion-weighted MRI

Introduction

Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and more than 90% of neoplasms arising from the kidney. Uninformative percutaneous kidney biopsies vary from 10 to 23%. As a result, 7.5–33.6% of partial nephrectomies in patients with small renal masses (SRM) are performed on benign renal tumors. The aim of this study was to assess the feasibility of the apparent diffusion coefficient (ADC) of the diffusion-weighted imaging (DWI) of MRI, as RCC imaging biomarker for differentiation of SRM.

Method

Adult patients (n = 158) with 170 SRM were enrolled into this study. The control group were healthy volunteers with normal clinical and radiologic findings (n = 15). All participants underwent MRI with DWI sequence included.

Results

Mean ADC values of solid RCC (1.65 ± 0.38 × 10^?3 mm²/s) were lower than healthy renal parenchyma (2.47 ± 0.12 × 10^?3 mm²/s, p < 0.05). There was no difference between mean ADC values of ccRCC, pRCC and chRCC (1.82 ± 0.22 × 10^?3 vs 1.61 ± 0.07 × 10^?3 vs 1.46 ± 0.09 × 10^?3 mm²/s, respectively, p = ns). An inverse relationship between mean ADC values and Fuhrman grade of nuclear atypia of solid ccRCCs was observed: grade I—1.92 ± 0.11 × 10^?3 mm²/s, grade II—1.84 ± 0.14 × 10^?3 mm²/s, grade III—1.79 ± 0.10 × 10^?3 mm²/s, grade IV—1.72 ± 0.06 × 10^?3 mm²/s. This was significant (p < 0.05) only between tumors of I and IV grades. Significant difference (p < 0.05) between mean ADC values of solid RCCs, benign renal tumors and renal cysts was observed (1.65 ± 0.38 × 10^?3 vs 2.23 ± 0.18 × 10^?3 vs 3.15 ± 0.51 × 10^?3 mm²/s, respectively). In addition, there was a significant difference (p < 0.05) in mean ADC values between benign cysts and cystic RCC (3.36 ± 0.35 × 10^?3 vs 2.83 ± 0.21 × 10^?3 mm²/s, respectively).

Conclusion

ADC maps with b values of 0 and 800 s/mm² can be used as an imaging biomarker, to differentiate benign SRM from malignant SRM. Using ADC value threshold of 1.75 × 10^?3 mm²/s allows to differentiate solid RCC from solid benign kidney tumors with 91% sensitivity and 89% specificity; ADC value threshold of 2.96 × 10^?3 mm²/s distinguishes cystic RCC from benign renal cysts with 90% sensitivity and 88% specificity. However, the possibility of differentiation between ccRCC histologic subtypes and grades, utilizing ADC values, is limited.

     

Diffusion tensor imaging and tractography of the sciatic and femoral nerves in healthy volunteers at 3T

Background

The aim was to clarify the normal fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the sciatic and femoral nerves at the level of the hip joint and to visualize the neural tracts with diffusion tensor imaging (DTI).

Methods

Twenty-four healthy volunteers (12 men and 12 women, age 20–29 years) underwent DTI for visualization with tractography and quantification of FA and ADC values on a 3 Tesla MRI (b value?=?800 s/mm², motion probing gradient, 11 directions, time to repeat/echo time?=?9000/72.6 ms, axial slice orientation, slice thickness?=?3.0 mm with no inter-slice gap, field of view?=?320?×?320 mm, 96?×?192 matrix, 75 slices, number of acquisitions?=?4). Regions of interest in the sciatic nerve were defined at the femoral head, the S1 root, and the midpoint levels. The femoral nerve was evaluated at 3–4 cm proximal to the femoral head level.

Results

The tractography of the sciatic and femoral nerves were visualized in all participants. The mean FA values of the sciatic nerve were increased distally from the S1 root level, through the midpoint, and to the femoral head level (0.314, 0.446, 0.567, p?=?0.001, respectively). The mean FA values of the femoral nerve were 0.565. The mean ADC values of the sciatic nerves were significantly lower in the S1 root level than in the midpoint and the femoral head level (1.481, 1.602, 1.591?×?10^?3?×?10^?3 mm²/s, p?=?0.001, respectively). The ADC values of the femoral nerve were 1.439?×?10^?3 mm²/s. FA and ADC values showed moderate to substantial inter- and intra-observer reliability without significant differences in gender or laterality.

Conclusion

Visualization and quantification of the sciatic and femoral nerves simultaneously around the hip joint were achieved in healthy young volunteers with DTI. Clinical application of DTI is expected to contribute to hip pain research.