多层螺旋CT评估肺腺癌血管生成可行性的初步研究

目的　探讨多层螺旋CT(MSCT)评估肺腺癌血管生成的可行性。方法　对 2 7例肺腺癌(直径≤ 4cm)患者行MSCT动态增强增强 (以 4ml/s的流率注入对比剂 90ml)。用随机软件 (timelapse)计算主动脉及病灶强化值 (Apa) ,并计算肿瘤 主动脉强化值比率。用随机软件 (functionalCT)计算灌注值及平均通过时间 ,获取灌注值及平均通过时间图 ,并与文献结果对照。结果　肺腺癌强化值为 (36 6 6± 13 5 3)HU ,与文献的结果 (34 1HU)差异无显著性意义 (t=0 981,P =0 335 )。肿瘤 大动脉强化值比率 [(15 72± 4 6 6 ) % ]与文献的结果 (14 6 % )差异亦无显著性意义 (t =1 2 4 4 ,P =0 2 2 5 )。灌注值 (平均 3 2 78ml·min-1·kg-1)在单光子发射体层摄影 (SPECT)测量的肿瘤灌注值 (1 36～ 2 98ml·min-1·kg-1)范围内。平均通过时间为 (17 6 0± 4 5 2 )s。结论　MSCT研究肺腺癌血管生成是可行的。     

胰腺多层螺旋CT灌注研究

目的　使用多层螺旋CT的肿瘤灌注软件 ,测量和评价正常胰腺和胰腺癌的CT灌注情况。方法　采用GELightspeedUltra多层螺旋CT的电影模式 ( 1s/周 ) ,5mm层厚 ,4层 ,12 0kV ,60mA ;采用高压注射器注射非离子型对比剂 50ml( 3 0 0mgI/ml) ,流率 3 5ml/s ,延迟 5s ,数据采集 45s。在SunUltraAW 4 0工作站使用Perfusion 2 (GE公司 )软件包 (去卷积算法 ) ,分别测量 3 7例正常胰腺和 3 7例胰腺癌及 3例无功能胰岛细胞瘤的血流量 (BF)、血容量 (BV)、平均通过时间 (MTT)和表面通透性(PS)的平均值 ,并进行统计学分析。结果　正常胰腺组的BF、BV、MTT和PS的平均值分别为 ( 3 3 86 2± 1596 1)ml·min- 1·kg- 1、( 2 67 3± 13 0 2 )ml·kg- 1、( 6 59± 2 59)s、( 2 88 2± 2 0 3 9)ml·min- 1·kg- 1。胰腺癌组的BF、BV、MTT和PS的平均值分别为 ( 2 3 2 3 1± 1841 2 )ml·min- 1·kg- 1、( 189 7± 160 6)ml·kg- 1、( 7 93± 3 92 )s、( 4 57 2± 2 61 6)ml·min- 1·kg- 1。胰腺癌组和正常胰腺组的BF、BV和PS的平均值差异具有显著性意义 (P值分别为 0 0 1、0 0 2 5和 0 0 0 3 )。胰腺癌和正常组织的MTT的平均值差异无显著性意义 (P =0 0 87)。结论　多层螺旋CT的胰腺灌注图像和数值比较容易获得。     

多层螺旋CT灌注成像对肾积水肾功能可复性的预测价值

目的 探讨多层螺旋CT（MSCT）灌注成像在肾积水肾功能可复性预测中的价值。方法 建立大白兔单侧输尿管部分梗阻肾积水模型。分为对照组，梗阻2、4及8周组，后3组在解除梗阻后再饲养4周，各组在梗阻解除前、后均行MSCT灌注扫描，测量右肾皮、髓质的血流量（BF）、血容量（BV）值并进行比较。然后处死实验动物制成普通病理切片，观察各组病理改变。结果 （1）MSCT检查显示梗阻2周组在梗阻解除后，其右肾皮质的BF、BV分别为（864±32）ml·100g^-1·min^-1、（19．5±0．9）ml／100g，较梗阻解除前[分别为（630±37）ml·100g^-1·min^-1、（14．0±1．2）ml／100g）]上升，差异有统计学意义（t值分别为-19．37、-12．11，P值均〈0．01）；右肾髓质的BF、BV分别为（182．1±7．5）ml·100g^-1·min^-1、（8．37±0．51）ml／100g，比梗阻解除前[分别为（132．6±3．9）ml·100g^-1·min^-1、（5．13±0．35）ml／100g）]也明显上升，差异有统计学意义（t值分别为-23．52、-11．51，P值均〈0．01）。（2）梗阻4周、8周组在梗阻解除后，其右肾皮质BF[分别为（525±15）、（512±10）ml·100g^-1·min^-1]、BV[分别为（12．8±0．6）、（9．4±1．0）ml／100g]与梗阻解除前[分别为（515±23）、（505±16）ml·100g^-1·min^-1，（12．2±0．8）、（10．3±0．5）ml／100g]相比，差异无统计学意义（P值均〉0．05）。（3）组织学上，梗阻时间短，解除梗阻后的病理变化较轻，梗阻时间长，解除梗阻后的病理变化重。结论 MSCT灌注成像不仅能够提供肾积水形态学的信息，又能提供血流灌注的信息，在肾积水肾功能可复性预测中有一定价值。     

CT脑灌注成像在短暂性脑缺血发作的初步研究

目的　探讨CT脑灌注成像在短暂性脑缺血发作 (TIA)的应用。方法　对 5例正常人及2 0例临床诊断TIA的病人行常规CT头颅平扫及CT脑灌注成像。在常规轴面CT扫描后一般选取基底节层面 ,经肘静脉团注对比剂 ,同时开始持续 40s的单层连续动态扫描 ,重建的 40幅动态图像使用CT脑灌注软件包进行处理 ,获得灌注图像。测量脑内感兴趣区的到达峰值时间及血流量 ,对这些图像进行定量分析。结果　CT脑灌注成像显示脑灰质灌注高于脑白质。正常人脑灰质的血流量及达峰时间分别为 378 2ml·min-1·L-1、7 8s ;脑白质分别为 112 5ml·min-1·L-1、9 9s。 2 0例TIA患者中有 15例发现与临床症状相对应的灌注异常区 ,表现为达峰时间延迟 ;另外 5例未发现灌注异常区。2 0例患者患侧局部灌注达峰时间 (TP)延长及对侧的平均达峰时间分别为 (11 8± 4 4)s和 (9 1±3 1)s,经配对t检验 :t=5 2 77,P <0 0 1;脑血流值分别为 (2 2 3 5± 38 7)ml·min-1·L-1和 (2 2 9 1±41 4)ml·min-1·L-1,经配对t检验 ;t=1 892 ,P =0 0 74。结论　CT脑灌注成像能够为TIA患者提供有价值的脑血流动力学信息 ,显示灌注异常的范围。     

兔VX2脑瘤血管生成的灌注CT研究

目的观察实验性兔VX2脑瘤的灌注CT改变,并与病理及免疫组织化学(简称免疫组化)结果对照,检验灌注CT反映脑瘤血管生成的效能.方法20只VX2脑瘤荷瘤兔按随机数字表分成3周以下组和3周以上组行灌注CT检查,测量肿瘤、瘤周及对侧正常脑组织的血容量(bloodvolume,BV),血流量(bloodflow,BF)和表面通透性(permeability surface,PS).大体标本观察肿瘤伊文思蓝染色级别.免疫组化观察血管内皮生长因子(vascular endothelial growth factor,VEGF)表达率和微血管密度(microvessel density,MVD).结果肿瘤区BV、BF和PS值[分别为(13.25±4.58)ml·100 g-1、(166.14±69.62)ml·100 g-1·min-1、8.01 ml·min-1·100 g-1]均明显高于瘤周[分别为(2.38±0.80)ml·100 g-1、(62.49±25.83)ml·100 g-1·min-1、0.03ml·min-1·100 g-1]及对侧正常脑组织[分别为(2.24±0.75)ml·100 g-1、(55.72±21.24)ml·100 g-1·min-1、0.04ml·min-1·100 g-1]差异有统计学意义(P值均=0.000).3周以上组肿瘤区BV、BF和MVD[分别为(16.41±4.12)ml·100 g-1、(208.77±63.00)ml·100 g-1·min-1、(61.20±12.93)个/高倍视野]均明显高于3周以下组[(10.09±2.27)ml·100 g-1、(123.51±47.18)ml·100 g-1·min-1、(41.40±7.34)个/高倍视野],差异有统计学意义(P值均＜0.01).肿瘤区MVD与BV(r=0.915,P=0.000)和BF(r=0.901,P=0.000)呈显著正相关,与PS(r=0.459,P=0.042)呈正相关;肿瘤蓝染级别与PS(rs=0.861,P=0.000)呈显著正相关.结论灌注CT可明确区分肿瘤与瘤周和正常组织,准确反映肿瘤的血管生成情况,为脑瘤评价提供重要资料.     

小型猪脂肪肝模型肝脏血流灌注的多层螺旋CT评价

目的采用多层螺旋CT（MSCT）灌注成像,探讨小型猪脂肪肝模型血流灌注状况。材料与方法实验组10头小型猪制备脂肪肝模型,同时设立3头小型猪为正常对照组。在0周、4周末、8周末分别进行肝脏CT灌注成像和肝穿刺病理活检,计算各项灌注参数。结果实验组4周末出现脂肪性肝炎、8周末出现脂肪性纤维化,对照组正常无脂肪肝。0周、4周末、8周末实验组的肝动脉灌注量（HAP）、门静脉灌注量（PVP）、总肝灌注量（THBF）均逐渐下降,分别为（28.00±11.42）、（19.30±9.12）、（17.52±16.29）ml·min^-1·100ml^-1,（79.58±21.78）、（41.87±28.41）、（22.84±13.44）ml·min^-1·100ml^-1,（107.58±25.70）、（61.17±31.87）、（40.37±17.19）ml·min^-1·100ml^-1,而肝动脉灌注指数上升（26.76±9.01）,（38.24±21.85）,（43.52±24.42）%,各组间差异有统计学意义（P〈0.05）。对照组0周、4周末、8周末HAP、PVP、THBF以及肝动脉灌注指数（HPI）组间差异均无统计学意义（P〉0.05）,分别为（31.30±15.01）、（27.19±11.60）、（21.33±8.57）ml·min^-1·100ml^-1,（91.68±25.67）、（69.02±21.21）、（81.90±14.60）ml·min^-1·100ml^-1,（122.98±33.97）、（96.21±24.00）、（108.23±13.48）ml·min^-1·100ml^-1,（26.21±9.01）、（28.91±9.56）、（24.88±8.21）%。同期对比,除0周外,实验组与对照组各灌注参数两两比较差异均有统计学意义（P〈0.05）。结论MSCT可以测量脂肪肝的血流灌注参数,与正常时期相比,小型猪脂肪肝的血流灌注参数发生了变化。     

CT灌注成像中表面通透性及血容量和血流量在评价C6胶质瘤血管生成中的作用

目的探讨CT灌注成像中表面通透性（PS）、血容量（CBV）、血流量（CBF）在评价肿瘤新生血管的功能和肿瘤生长行为方面的差别。方法成年Wistar大鼠60只，雌雄各半。将大鼠按体重进行编号，然后按数字表法将大鼠随机分为3组，每组20只（头部尾状核区接种C6胶质瘤），分别于接种后第5、13、20天3个时间点依次进行CT灌注检查并获得PS、CBV和CBF图。采用方差分析及SNK检验比较不同部位（肿瘤中心、肿瘤周边、交界区、对侧脑组织）、不同时间点的PS、CBV和CBF的变化。结果肿瘤中心区，接种后第5、13、20天3组间CBF[分别为（280．33±8．82）、（388．33±14．00）、（116．16±11．54）ml·100g^-1·min^-1]，CBV[分别为（7．75±O．27）、（12．73±0．98）、（5．14±0．66）ml·100g^-1]，PS[分别为（3．94±0．15）、（8．47±0．34）、（5．20±0．65）ml·100g^-1·min^-1]差异均有统计学意义（分别F=4．421，P=0．013；F=11．370，P=0．000；F=15．789，P=0．000）。5、13、20d组间肿瘤周边区PS分别为（5．80±0．49）、（8．40±3．04）、（15．52±0．71）ml·100g^-1·min^-1，肿瘤交界区PS分别为（0．42±0．14）、（5．48±0．21）、（10．24±0．61）ml·100g^-1·min^-1，差异均有统计学意义（F=13．567，P=0．000；F=12．470,P=0．000）。肿瘤周边区各组间CBF、CBV差异无统计学意义（F=1．176,P=0．336；F=0．148,P=0．710），肿瘤交界区各组间CBF分别为（175．33±12．95）、（275．50±13．76）、（246．33±12．81）ml·100g^-1·min^-1，CBV分别为（4．15±0．47）、（8．05±0．30）、（7．54±0．89）ml·100g^-1，差异均有统计学意义（F=24．176，P=0．000；F=17．148，P=0．000；F=15．791，P=0．000）。结论CBV、CBF反映的是肿瘤血管的数量，PS直接反映肿瘤新生血管的功能状态，评价肿瘤的生长行为。     

兔VX2肿瘤介入治疗前后肿瘤血管生成的多层螺旋CT灌注成像研究

目的 探讨多层螺旋CT（ISCT）灌注成像在定量评价软组织恶性肿瘤介入治疗前后肿瘤血管生成和介入治疗后早期疗效监测中的应用价值。方法 24只成功种植VX2肿瘤的新西兰大白兔，数字表法随机分为介入组和对照组，每组12只，分别于肿瘤种植后第14天、介入治疗后第3天行常规CT平扫和灌注扫描，计算肿瘤组织和正常肌肉组织的血流量（BF）、血容量（BV）、平均通过时间（MTT）和表面通透性（PS）值，分析各参数之间的差异性；并将各灌注参数分别与肿瘤微血管密度（IVD）值和血管内皮生长因子（VEGF）平均吸光度（A）值进行相关性分析。结果 肿瘤种植后第14天，介入组肿瘤BF、BV、MTT、PS值分别为（303．3±69．9）ml·100g^-1·min^-1、（7．02±3．10）ml／100g、（1．99±0．28）s、（65．9±9．4）ml·100g^-1·min^-1，与正常肌肉组织相比[分别为（11．8±5．0）ml·100g^-1·min^-1、（1．04±0．47）ml／100g、（17．92±7．19）s、（13．1±6．4）ml·100g^-1·min^-1]差异有统计学意义（F值分别为4285．82、1867．46、413．04、698．42，P〈0．01）；与对照组肿瘤的各参数值差异无统计学意义（F值分别为2．47、2．03、0．02、0．53，P〉0．05）。介入组肿瘤IVD值和VEGF平均A值分别为（50．1±4．1）个／高倍视野、0．352±0．011，与对照组肿瘤[分别为（50．2±3．7）个／高倍视野、0．352±0．009]差异无统计学意义（F值分别为0．02、0．19，P〉0．05）。介入治疗后第3天（即种植后第18天），介入组肿瘤BF、BY、MTT、PS、MYD值和YEGF平均A值分别为（7．5±24）ml·100g^-1·min^-1、（1．20±0.23）ml／100g、（3．29±0.57）s,（40±1．5）ml·100g^-1·min^-1、（16．0±2．4）个／高倍视野、0．215±0．008，与对照组相比[分别为（390．2±116．3）ml·100g^-1·min^-1、（8．47±2．53）ml／100g、（1．88±0．34）s、（76．9±11．3）ml·100g^-1·min^-1、（84．8±5．6）个／高倍视野、0．366±0．013]差异有统计学意义（F值分别为10166．91、1310．19、272．84、1649．80、1239．72、4168．91，P〈0．01）；与介入治疗前相比，差异也有统计学意义（t值分别为74．53．49．62、-16．82、35．36、50．41、65．64，P〈0．01）。、肿瘤BF、BV、PS值与IVD值和VEGF平均A值呈正相关（r值均〉0．7，P〈0．05）；MTT值与VEGF平均A值呈负相关（r=-0．78，P〈0．05），而与肿瘤IVD值无明显相关性（r=-0．315，P〉0．05）。结论 NSCT灌注成像是一种定量评价肿瘤血管生成、血流灌注及血管通透性改变的功能成像方法，可以无创、准确地对肿瘤介入治疗早期疗效进行定量评价和动态监测。     

多层螺旋CT灌注成像对脑肿瘤血管通透性的研究

目的　运用多层螺旋CT(MSCT)灌注成像的方法获取脑肿瘤组织的表面通透性 (PS)值 ,研究脑肿瘤的肿瘤血管通透性。资料与方法　对 32例脑肿瘤患者行MSCT灌注成像 ,先用常规 10mm层厚的CT平扫确定肿瘤中心层面 ,然后进行肿瘤灌注扫描 ,采用电影扫描技术 (1r/ 0 .5s) ,层厚 5mm/ 4i,重建层厚 10mm/ 2i;注射流率3.5ml/s,剂量 5 0ml,延迟时间 5s,扫描总时间 5 0s。扫描图像经ADW 4 .0工作站处理 ,计算并分析PS灌注图像和PS值。结果　 32例脑肿瘤包括 6例Ⅰ～Ⅱ级星形细胞胶质瘤 ,10例Ⅲ～Ⅳ级星形细胞胶质瘤 ,8例转移瘤 ,8例脑膜瘤。所有肿瘤的PS值均明显大于对侧正常的脑白质和脑灰质 ,低级别胶质瘤、高级别胶质瘤、转移瘤和脑膜瘤的PS值分别为 5 .19～ 17.5 4 3(9.84 4 2± 5 .4 0 5 84 )、2 1.116～ 4 9.82 4 (32 .8784± 10 .70 139)、12 .2 94～ 4 8.196 (2 9.6 16 8±14 .74 735 )、2 5 .2 5 3～ 85 .94 8(5 6 .2 0 2 6± 17.4 0 347) ,单位是ml·10 0g-1·min-1。各组PS值两两比较经t检验发现脑膜瘤的PS值与其他 3组相比有显著性差异 (低级别 /脑膜瘤t=5 .70 2 ,P <0 .0 0 1,高级别 /脑膜瘤 ,t=3.5 0 4 ,P <0 .0 1,转移瘤 /脑膜瘤 ,t=3.2 96 ,P <0 .0 1) ,高级别胶质瘤及转移瘤的PS值与低级别胶质瘤的P     

MR灌注成像在前列腺疾病诊断中作用的初步探讨

目的探讨MR灌注成像在前列腺良恶性病变中的初步应用,评价血管内皮生长因子(VEGF)和微血管密度(MVD)与MR灌注成像各指标的关系。方法对临床诊断为前列腺疾病的70例患者,其中良性前列腺增生(BPH)42例,前列腺癌(PCa)28例,进行MR灌注成像,并对标本进行免疫组织化学检测;分析病变的灌注曲线最大线性斜率(SSmax)、T2*弛豫率(△R2* peak)与免疫组织化学检查结果(VEGF、MVD)的相关性。结果(1)BPH组增生结节灌注曲线的SSmax及△R2*peak分别为:33．5±3．1、1．5±0．1;PCa组癌灶灌注曲线的SSmax及△R2*peak分别为:58．4±4．7、3．1±0．5,两者之间差异有统计学意义(t值分别为2．13、2．29,P值均<0．05);PCa组高、中、低分化腺癌的SSmax分别为:52．3±3．4、56．4±4．3、60．7±5．2,差异有统计学意义(F=132．04,P< 0．05),△R2*peak分别为:2．9±0．4、3．1±0．5、3．2±0．7,差异有统计学意义(F=114．82,P<0．05)。(2)BPH组VEGF阳性9例,MVD值为22．76±6．54;PCa组VEGF阳性为24例,MVD值为71．38±9．17;PCa的VEGF和MVD的表达水平明显高于BPH患者(X2=27．86,P<0．01;t=20．4,P< 0．01),PCa、BPH的VEGF表达与MVD表达呈正相关性(P<0．01);灌注加权成像(PWI)参数SSmax、△R2*peak与VEGF、MVD具有相关性(P<0．01)。结论PWI的有关指标(SSmax、△R2*peak)与MVD和VEGF的表达水平相关,有可能为前列腺疾病良恶性的鉴别提供信息。     

Stress MR imaging for evaluation of popliteal artery entrapment

The popliteal artery entrapment (PAE) syndrome has been recognized as a cause of arterial occlusion in young people. It is the result of an anomaly of the relationship between the popliteal artery and the gastrocnemius muscle. Eight young healthy volunteers (16 legs) and six patients (10 legs) with suspected PAE underwent magnetic resonance (MR) imaging. Gradient-echo images were obtained in axial planes with the leg at rest and during active plantar flexion against resistance. Imaging at rest allowed identification of PAE signs in only one leg, which had an anomalous medial course of the popliteal artery. In the other cases, only the stress technique was able to show signal loss in the popliteal artery due to muscular compression (two legs) or the presence of accessory muscle slip around the vessel (two legs), as confirmed at surgery. MR imaging is therefore a useful technique for the diagnosis of PAE because of its capability of combining information obtainable with other modalities.     

MR imaging of muscle and tender points in fibromyalgia

Fibromyalgia is a syndrome manifested by chronic, diffuse muscu-loskeletal aching and soreness, palpable muscle tender points, and other symptoms. Standardized clinical diagnostic criteria have recently been developed. Skeletal muscle has been postulated as the end organ in this disease. Biochemical, histologic, electromyographic, and conventional radiographic studies have demonstrated no definitive abnormality. This study sought to establish whether magnetic resonance (MR) imaging could demonstrate any abnormality in these patients. Eighteen patients were entered in the study, 14 of whom were able to complete their examinations. T1 -weighted, T2-weighted, gradient-echo, and STIR (short-tau inversion-recovery) sequences were performed in all patients, with selected patients examined with T1weighted, gadopentetate dimeglu-mine-enhanced sequences. The trapezius and suboccipital regions were imaged in patients who, clinically, had active fibro-myalgia. No abnormalities could be detected. The authors conclude that the conventional MR imaging used in this study was unable to depict any primary skeletal muscle abnormality in fibromyalgia.     

Controversies in cervical spine imaging in trauma patients

No area of emergency radiology has generated as much discussion in recent years as the subject of cervical spine imaging for trauma patients. This review will be in three parts. The first will examine the indications for cervical imaging and will focus on those factors that make patients at high risk or low risk for cervical injury. The second part will discuss the merits of radiography and computed tomography as the main screening diagnostic examination. In addition to the roles of each modality in the evaluation process, such factors as efficacy of diagnosis, time (duration) of study, and cost will be discussed. Finally, the third part will explore the methods currently employed to clear the cervical spine in comatose patients.Presented at the Annual Meeting of the American Society of Emergency Radiology, Las Vegas, Nevada, 22–25 October, 2003     

Uterine contractions: Possible diagnostic pitfall at MR imaging

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent–enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.     

Brodie Abscess: MR imaging appearance in 10 patients

The magnetic resonance (MR) imaging features of Brodie abscess have not yet been fully evaluated. Ten patients with Brodie abscess, eight of long bone and two of vertebra, were studied with MR imaging. Long bone abscess had a characteristic “target” appearance with four layers: (a) a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR (short-inversion-time inversion recovery) images, (b) an inner ring isointense to muscle on T1-weighted images and with high signal intensity on T2-weighted and STIR images, (c) an outer ring hypoin-tense on all images, and (d) a peripheral halo hypointense on T1-weighted images. In six of eight cases, a soft-tissue mass was found. The two vertebral abscesses had a less specific appearance, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR images. Only the peripheral halo was clearly identified in both cases.     

Dynamic contrast-enhanced MR imaging assessment of vascularized free fibular grafts

Magnetic resonance (MR) imaging may be a noninvasive method for assessing perfusion of vascularized bone grafts placed for treatment of avascular necrosis. One proximal femur of seven beagles was devascularized, with insertion of a vascularized fibular graft. MR imaging at 1 week (seven dogs) and 6 weeks (five dogs) after surgery included pre- and postcontrast spin-echo sequences, unenhanced twodimensional time-of-flight (TOF) vascular imaging, and dynamic gradient-echo imaging during infusion of gadolinium. Relative signal intensity values of selected regions obtained from the dynamic gradientecho images were plotted as percent enhancement versus time. In the operated hip, MR imaging did not show enhancement in six of seven femoral heads and greater trochanters at 1 week after surgery, with similar results after 6 weeks. MR imaging of fibular grafts 6 weeks after surgery showed an initial rapid increase in enhancement and a subsequent slower increase in five of five dogs, although no enhancement was seen in six of seven dogs at 1 week. These findings contrasted with a rapid initial increase in enhancement followed by slow decline in non-operated hips. Two-dimensional TOP imaging did not show the vascular pedicle of the graft in any dog. Findings of radionuclide bone scanning performed 1 week after surgery were consistent with devascularization of the operated femur and fibular graft. However, tetracycline distribution and histologic findings confirmed the viability of five of five grafts within the devascularized femurs 6 weeks after surgery. Thus, dynamic contrast-enhanced MR imaging at 6 weeks after surgery is valuable for assessing vascular bone graft perfusion, while similar imaging at 1 week may suggest otherwise.     

Adrenal tissue characterization with 0.5-T MR imaging: Value of T2*-weighted images

The authors investigated the value of magnetic resonance (MR) imaging at 0.5 T for distinguishing adrenal adenomas from adrenal metastases. The series included 23 adrenal adenomas (18 nonhyperfunctioning, five hyperfunctioning) and 23 adrenal metastases from various organs. Adrenal tumor–liver signal intensity ratios on T1-, T2-, and T2*-weighted images were calculated for adrenal tissue characterization. Adrenal adenomas were more precisely distinguished from adrenal metastases on T2*-weighted images (21 of 23, 91%) than on T2-weighted images (15 of 23, 65%). T1-weighted images were not useful for this distinction. In conclusion, T2*-weighted images were better than routine T2-weighted images for distinguishing adrenal adenomas from adrenal metastases. It can be postulated that the total signal intensity of adrenal adenomas, which contain some fat components, decreased on T2*-weighted images because of an out-of-phase effect.     

Right-side aortic arch with aneurysm of aberrant left subclavian artery: MR imaging appearance.

Reports of aneurysms of the subclavian artery in both normal and anomalous aortic arches have been rare. The authors describe a patient with a right-side aortic arch and an aneurysm of the aberrant left subclavian artery, which, to the authors' knowledge, is a previously unreported association. At presentation, the aneurysm appeared as a calcified left superior mediastinal mass. Magnetic resonance imaging enabled preoperative diagnosis and guided surgical planning.     

MR angiography of congenital heart disease: Value of segmented two-dimensional inflow technique and maximum-intensity-projection display

Magnetic resonance (MR) angiography of the cardiovascular system was evaluated in 41 patients with congenital heart disease by using a two-dimensional (2D) inflow technique based on a magnetization-prepared gradient-echo pulse sequence with segmented k-space data acquisition and electrocardiographic gating at 0.5 T. Inversion and saturation prepulses were used to suppress stationary tissue and enhance intravascular signal. Presaturation slabs were applied where certain vascular structures had to be suppressed. Sequence parameters were optimized by evaluating signal intensity and contrast characteristics for various flip angles and inversion and saturation delay times. The heart and intrathoracic vasculature were encompassed with 40–50 overlapping sections. Both 2D angiograms and maximum-intensity-projection images were evaluated. Combining data sets acquired in the sagittal and transverse orientations provided the most satisfactory information about the pulmonary arteries. The highest signal-to-noise ratios were obtained with a flip angle of 65° and short prepulse delay times. Two-dimensional MR angiography can provide useful diagnostic information but requires a thorough understanding of in-plane and hemodynamically induced signal intensity changes.