鼻咽癌CT灌注成像及其生物学相关性研究

目的研究鼻咽癌CT灌注值与肿瘤微血管密度（MVD）、肿瘤分期的关系，探讨多层螺旋CT灌注成像对鼻咽癌的临床应用价值。方法49例鼻咽部CT灌注检查中，鼻咽癌组30例，鼻咽癌放疗后组14例，正常鼻咽部5例，测量鼻咽癌和鼻咽黏膜位置的血流量（BF）、最大强化指数（PEI）、峰值到达时间（TTP）及血容量（BV）作为灌注指标，其中16例鼻咽癌活检组织行免疫组织化学CD34单抗染色后，Weidner方法计数MVD。各组灌注值比较行方差分析，CT灌注值、肿瘤分期与MVD之间行Spearman等级相关分析。结果49例中1例鼻咽癌灌注检查失败。鼻咽癌组（29例）肿瘤CT灌注值BF为（48．6±16．9）ml·100g^-1·min^-1，PEI为（32．3±7．9）HU，TTP为（17．5±4．9）s，BV为（12．8±4．4）ml·100g^-1；正常对照组（5例）BF、PEI、TTP、BV值分别为（15．9±5．9）ml·100g^-1·min^-1、（12.6±1．3）HU、（22．6±6．9）s、（3．5±0．5）ml·100g^-1；鼻咽癌放疗后组（14例）BF、PEI、TTP、BV值分别为（25．2±7．0）ml·100g^-1·min^-1、（19．8±5．9）HU、（22．6±4．3）s、（6．1±2．4）ml·100g^-1，三组各灌注值差异有统计学意义（P值均〈0．01）；相关分析显示，鼻咽癌组（29例）中TNM分期（其中Ⅰ期3例，Ⅱ期9例，Ⅲ期10例，Ⅳ期7例）与PEI和BV存在相关性（r值分别为0．48和0．50），与BF和TTP无明显相关性（r值分别为0．23和0．22）；16例鼻咽癌MVD为（30．8±12．6）个／高倍镜视野，与其BF（51．4±17．0）ml·100g^-1·min^-1、PEI（33．2±9．6）HU和TTP（16．3±4．1）8存在相关性（r值分别为0．85、0．60和0．78），与BV（13．2±5．6）ml·100g^-1弱相关（r=0．48）。结论鼻咽癌有着特征的CT灌注表现，多层螺旋CT灌注成像的灌注值可以反映鼻咽癌微血管密度特征，PEI和BV值与鼻咽癌的TNM分期存在一定的相关性。     

正常肾和肾细胞癌CT灌注成像及其与微血管密度相关性的研究

目的测量并初步确定正常肾脏皮质CT灌注各参数值范围及肾细胞癌（RCC）各CT灌注参数值变化特点;分析RCC各CT灌注参数值与其微血管密度（MVD）计数的关系。资料与方法对26名肾功能正常的志愿者及30例经手术病理证实的RCC患者行CT灌注扫描,所得数据送入Advanced Workstation4.2工作站,应用perfusion3软件分别测量正常肾脏及肿瘤各CT灌注参数值,包括血流量（BF）值、血容量（BV）值、平均通过时间（MTT）值及毛细血管表面通透性（PS）值;用免疫组织化学过氧化物酶标记的链霉素卵白素法（SP法）检测RCC中MVD的表达（人工计数）;分析RCC实性部分与正常肾脏皮质间各CT灌注参数值差异是否存在统计学意义,分析RCC各CT灌注参数值与其MVD计数的相关性,以上两组数据的采集应用双盲法。结果26名正常人肾脏皮质CT灌注BF值（502.73±99.03）ml·min^-1.100g^-1,BV值（25.35±9.12）ml/100g,MTT值（3.13±0.83）s,PS值（62.15±12.29）ml·min^-1.100g^-1;30例肾癌患者CT灌注BF值、BV值、MTT值及PS值分别为（301.74±250.41）ml·min^-1.100g^-1、（18.17±11.54）ml/100g,（6.62±4.91）s和（21.59±12.75）ml·min^-1.100g^-1,MVD计数为（47.67±30.92）条。RCC与正常肾脏皮质间各CT灌注参数值差异有统计学意义（P〈0.01,tBF=4.904,tBV=3.243,tMTT=-4.376,tPS=14.973）,正常肾脏皮质的BF值、BV值及PS值均高于肾癌实性部分;MTT值则相反。肾癌CT灌注的BF值和BV值与其MVD计数呈正相关,r值分别为0.736和0.632（P〈0.01）;而MTT值与其MVD计数呈负相关,r值为-0.487（P〈0.01）;PS值与其MVD计数无相关性。结论RCC CT灌注参数BF值、BV值和MTT值与MVD计数存在相关性,这些CT灌注参数值在一定程度上可反映活体的肿瘤血管生成状况和恶性程度,有助于临床制定治疗方案,判断疗效及预后。     

CT灌注成像在腮腺肿瘤鉴别诊断中的临床价值

目的探讨多层螺旋CT灌注成像技术定量评价腮腺良、恶性肿瘤的血液动力学特点及其对腮腺良恶性肿瘤的鉴别诊断价值。方法53例患者共57个病变，其中良性肿瘤35例，恶性肿瘤18例，全部经术后病理证实。术前行CT灌注检查。采用Philips perfusion功能软件包获取组织的时间密度曲线（time density calve，TDC）及CT灌注参数，包括灌注量、增强峰值（PH）、达峰时间（TTP）、血容量（BV）、平均通过时间（MTT）。采用Wilcoxon符号秩和检验进行统计学处理。结果腮腺良性肿瘤的CT灌注参数的中位数及四分位间距[25％CI 75％（Q1，Q2）]分别为：灌注量73．5（18．7，113．3）ml·100g^-1·min^-1、PH 34．5（17．7，53．1）HU、TTP 20．0（13．6，34．4）S、BV 38．5（29．1，63．3）ml·100g^-1、MTT 7．6（4．5，28．7）s。腮腺恶性肿瘤的CT灌注参数分别为：灌注量135．9（101．4，195．2）ml·100g^-1·min^-1，PH 49．1（32．7，59．4）HU，TTP 12．9（11．3，14．6）s，BV 67．5（52．4，109．5）ml·100g^-1，MTT 6．0（5．1，7．6）s。统计结果显示，CT灌注参数BF、BV、TTP的中位数及四分位间距在腮腺良恶性肿瘤之间差异具有统计学意义（P值均〈0．05），而PH、及MTT之间差异无统计学意义（P〉0．05）；腺淋巴瘤、其他良性肿瘤、恶性肿瘤的TDC的差异也有统计学意义（P值均〈0．05）。结论CT灌注扫描技术对腮腺良恶性肿瘤的鉴别诊断具有一定价值。     

头颈部肿瘤CT灌注成像表现与微血管生成因子表达水平的相关性研究

目的研究头颈部肿瘤CT灌注与肿瘤血管生成因子（VEGF）的相关性。方法对85例共88个（恶性77个，良性11个）头颈部肿瘤术前行CT灌注检查。采用螺旋CT机自带软件绘制感兴趣区（ROI）的时间-密度曲线（TDC）并计算ROI强化峰值（PH）、达峰时间（PT）、平均通过时间（MTT），病灶相对强化峰值（RPH）和灌注量（PF）。其中35例切取与CT灌注靶层面相同的组织切片，行CD34、VEGF抗体免疫组织化学染色，分析肿瘤CT灌注成像表现与微血管密度（MVD）和VEGF表达的相关性。结果（1）头颈部肿瘤CT灌注成像TDC主要有3种类型，77个恶性肿瘤中53个（68．9％）表现为速升速降型；9个淋巴瘤中6个TDC表现为低平型曲线，与68个其他肿瘤中仅有9个为低平型曲线相比差异有统计学意义（P〈0．05）。（2）甲状腺癌呈高灌注，其PF（中位数为82．2ml·min^-1·100g^-1）与淋巴瘤PF（中位数为24．5ml·min^-1·100g^-1）、头颈鳞癌PF（中位数为23．8ml·min^-1·100g^-1）相比差异有统计学意义（P〈0．05）。（3）11个良性肿瘤的MVD均数为（44．7±3．4）条／高倍视野，24个恶性肿瘤的MVD为（49．6±14．8）条／高倍视野，良恶性肿瘤间差异无统计学意义（P〉0．05）；VEGF在恶性肿瘤呈强阳性者15个，弱阳性9个；在良性肿瘤呈强阳性1个，弱阳性10个，VEGF的表达强阳性率在良、恶性肿瘤差异有统计学意义（P〈0．01）。（4）MVD（中位数40．0）与PH（中位数26．9）、RPH（中位数14．5）和PF（中位数46．8）有明显相关性（r值分别为0．35、45．49和0．41），VEGF（中位数4．0）表达与MTT（中位数16．7）呈负相关（r=-0．41）。结论CT灌注成像TDC形态对头颈部肿瘤诊断及鉴别诊断有一定的帮助。MVD、VEGF与CT灌注相关，CT灌注成像可以反映肿瘤微循环情况。     

注射速率对孤立性肺结节64层螺旋CT灌注成像影响的初步研究

目的：利用64层螺旋CT探讨孤立性肺结节CT灌注成像技术中对比剂注射速率对结果的影响。方法：对50例孤立性肺结节患者进行前瞻性研究。随机将患者分为两组，注射速率分别为3ml／s（组1）及5ml／s（组2）；男性34例，女性16例。年龄范围28～73岁，平均年龄56．02±9．11岁。其中，43例通过手术证实；2例通过CT引导经皮肺穿刺活检证实；1例通过纤支镜活检证实；4例同时发现全身多处转移性肿瘤。结果：组1中，血流量值：49．006±42．429ml·100g^-1·min^-1、血容量：3．358±4．608ml／100g，平均通过时间：6．307±3．772s，表面渗透性：9．378±9．040ml·100g^-1·min^-1。组2：血流量：52．917±61．206ml·100g^-1·min^-1，血容量：3．045±4．671ml／100g，平均通过时间：6．079±3．831s，表面渗透性：8．142±7．082ml·100g^-1·min^-1。组1与组2结节血流量（P=0．249〉0．05）；血容量（P=0．737〉0．05）；平均通过时间（P=0．776〉0．05）；表面渗透性（P=0．454〉0．05）。不同注射速率的两组孤立性肺结节灌注值统计学差异无统计学意义（P〉0．05）。结论：不同的对比剂注射速率（3ml／s和5ml／s）对64层螺旋CT孤立性肺结节灌注成像无明显影响。     

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灌注强化指标和微血管密度与非小细胞肺癌淋巴结转移的相关性

目的：应用16层 MSCT 灌注成像定量评价肺癌肿瘤血管生成,并探讨 CT 灌注成像强化指标和肿瘤微血管密度（MVD）与肺癌淋巴结转移的关系及其价值。方法：对72例非小细胞肺癌行 CT 灌注扫描,根据首过期肿块强化的时间-密度曲线（TDC）计算肿瘤的灌注强化指标,根据病理结果分为有淋巴结转移组和无淋巴结转移组,并对肿瘤 MVD 计数。淋巴结转移组与无转移组各观察指标的差异采用 t 检验或 t＇检验;将 CT 灌注强化指标分别与 MVD 做相关性分析;利用 ROC 曲线分析 MVD 和 CT 灌注强化指标评价肺癌淋巴结转移的诊断效能。结果：肺癌淋巴结转移组（26例）MVD计数高于无淋巴结转移组（27例）,MVD 分别为（59．50±7．08）、（49．68±8．10）个/0．74mm2（t ＝-5．045,P ＜0．01）。淋巴结转移组肿块的 BV 高于无淋巴结转移组（BV 分别为8．99±3．25、5．94±2．88）,差异有统计学意义（t 值为-4．159, P ＜0．05）。BV、BF、MTT 均与 MVD 呈正相关,其中 BV 与 MVD 的相关系数最高（r＝0．895,P ＜0．05）。利用 ROC 曲线分析,MVD、BV 判断肺癌淋巴结转移有较高的诊断价值（曲线下面积分别为0．850和0．873,P ＞0．05）;当以 MVD≥54个/0．74mm2或 BV≥7ml/100g 作为强烈提示肺癌淋巴结转移的可能性时,其敏感度、特异度、诊断符合率、阳性预测值和阴性预测值均较高。结论：CT 灌注中的 BV 值可作为术前判断肺癌淋巴结转移的重要指标之一。     

多层CT灌注成像诊断周围型肺癌及与微血管密度对照研究

目的:探讨多层螺旋CT(MSCT)灌注成像技术诊断肺癌的临床价值及其与肿瘤微血管密度(MVD)的相关性。方法:利用16层MSCT灌注成像技术前瞻性研究38例经手术病理证实的肺肿瘤(周围型肺癌25例,肺良性肿块13 例),并与25例肺癌的免疫组化法MVD进行相关性研究。采用Perfusion 2体部肿瘤灌注软件包分析以下灌注参数:血液流速(BF)、血流量(BV)、平均通过时间(MTT)和表面通透性(PS)。结果:肺癌各项CT灌注参数值均高于肺良性肿块, 其中MTT和PS值在两组之间差异有显著性意义(P<0．05),BV值差异有极显著性意义(P<0．01);肺癌的MVD明显高于肺良性肿块(P<0．05),肺腺癌MVD高于肺鳞癌(P<0．05);肺癌仅BV值与其MVD呈正相关性(r=0．852,P< 0．01)。结论:MSCT灌注成像有助于周围型肺癌的诊断及与良性肿瘤的鉴别诊断,其病理基础与肿瘤微血管密度有关。     

多层螺旋CT在肺癌诊断中的临床应用

目的：探讨多层螺旋CT与肺癌早期诊断及预后的关系。方法：对我院2007年4月～2008年7月拟诊肺癌的152例患者行多层螺旋CT扫描,评价CT对肺癌早期诊断的作用,比较肺癌CT灌注参数与肌肉组织灌注参数的差异。接受化疗、放疗或同步放化疗且符合疗效评价标准患者中观察治疗前后CT灌注参数是否有变化,评价CT灌注参数的变化在监测化放疗疗效,评价预后中有无价值。结果：CT检查鉴别诊断肺部肿物良、恶性的灵敏度、特异性、阳性预测值、阴性预测值和准确性分别为90．5％、86．7％、98．4％、50．0％、90．1％。肺癌患者肿瘤组织和肌肉组织的BF、BV、MTT、PS（均P〈0．01）。在NSCLC中,缓解组的BF、BV值高于未缓解组,（P〈0．05）;缓解组的MTT值较低、PS值略高（P〉0．05）。PS值升高组的无进展生存期和总生存期均低于PS值降低组（均P〈0．01）。结论：CT在肺癌早期诊断中具有一定临床意义,肺癌的BF、BV和PS值明显高于肌肉组织,MTT明显低于肌肉组织。PS值升高,提示预后不良。对于化疗后早期灌注值明显升高、PS值升高的患者,可望提示临床在出现肿瘤进展前考虑提早联合放疗或靶向治疗。     

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.     

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.     

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     

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.     

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.     

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.     

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.