肝细胞癌MR动态增强表现与病理的相关性研究

目的 探讨肝细胞癌（hepatocellular carcinoma,HCC)动态增强表现的病理基础。资料与方法 分析35例经手术病理证实的HCC动态增强MRI征象及病理表现，图像分析包括HCC动脉期，门脉期双期强化表现，动脉期强化强度，病理分析包括癌细胞分化程度，癌组织结构类型。结果 根据动脉期，门脉期信号强度及其演变分为Ⅰ，Ⅱ，Ⅲ型动态强化类型，Ⅰ型为动脉期强化高于或等于肝实质，门脉期低于肝实质；Ⅱ型为动脉期，门脉期强化均高于或等于肝实质；Ⅲ型为动脉期，门脉期强化均低于肝实质，35例中Ⅰ型强化19例，Ⅱ型12例，Ⅲ型4例，Ⅰ型强化中分化差的HCC比率显著高于其他类型（精确检验，P=0.007)，Ⅱ型强化中分化好的HCC比率显著高于其他类型（精确检验，P=0.011)，实体型与硬化型主要表现Ⅰ型强化，梁索型及假腺管型Ⅰ型和Ⅱ型强化均较多见，动脉期不同强化程度HCC其癌细胞分化无显著性差异，但明显强化的HCC以分化差多见。结论 MR动态增强类型可反映HCC的分化程度，并在一定程度上可反映出HCC的血供，可为HCC外科手术和介入治疗提供无创的影像学依据，并有助于判断预后。     

肝硬化结节与小肝癌的MRI研究

目的:回顾性分析肝硬化合并小肝癌、再生结节(RN)及肝不典型增生结节(DN)的MR表现,探讨其MR诊断与鉴别诊断。方法:收集50例结节性肝硬化病例MR检查资料,患者行正反相位T1WI、脂肪抑制T2WI、动态增强扫描和弥散加权(DWI)扫描,总结肝内结节的信号特点。结果:RN在T1WI脂肪抑制上多为等信号或稍高信号,T2WI多为低信号,增强后与周围正常肝组织强化相似或信号稍低;DN在T1WI多为较高信号,T2WI多为稍低或等信号,增强后强化不明显;癌结节T1WI多为稍低或等信号,偶有稍高信号,T2WI多为较高信号,DWI为高信号,强化多为动脉中晚期强化,门静脉期以后强化减退。结论:磁共振平扫加动态增强能对大多数RN、DN和小肝癌结节做出明确诊断和鉴别。     

磁敏感加权成像在肝硬化结节多步癌变中的临床应用

目的探讨磁敏感加权成像在肝硬化结节多步癌变中的临床应用,旨在能够更早发现癌前病变、小肝癌。方法回顾性分析经病理、手术证实的45例肝硬化患者结节的MRI平扫、增强及DWI、SWI图像,分析不同性质结节的信号变化。结果所有序列共检出结节76个,其中43个RN(SWI呈低信号43个),21个DN(SWI呈低信号15个、呈高信号6个),12个s HCC(SWI呈高信号11个、呈低信号1个)。结论 SWI可以从不同性质结节内铁含量变化的角度进行评价,为癌前病变与小肝癌的进一步鉴别诊断提供新的影像依据。     

局灶性肝紫癜的CT及MRI表现

【摘要】目的：探讨局灶性肝紫癜（FPH）的CT及MRI表现。方法：回顾性分析6例经病理证实的局灶性肝紫癜患者的临床资料及CT图像，其中2例同时行MRI检查。图像分析包括病灶的数目、部位、大小、形态、CT及MR平扫以及强化特征等。结果：6例患者中，男3例，女3例，年龄（52.8±9.9）岁； 5例为单发病灶， 1例有2个病灶。病灶位于肝右叶5个，肝左叶2个；边界模糊6个，边界清晰1个；平均直径（长径与短径之和的平均值）9.5~23.0mm，均值（15.5±5.3）mm。CT平扫：病灶均呈略低密度，平均CT值为（44.3±13.0）HU，邻近肝实质平均CT值为（57.3±7.3）HU，两者间的差异有统计学意义（P<0.05）。CT增强扫描：病灶均呈渐进性强化，其中4个呈均匀轻度强化，2个呈离心性强化，1枚呈轻度环形强化；动脉期及静脉期，病灶平均CT值分别为（58.0±9.7）和（80.4±15.9）HU，邻近肝实质分别为（75.9±9.4）和（102.3±10.4）HU，两期图像上病灶与邻近肝实质间的差异均有统计学意义（P<0.05）。2个病灶在MR平扫T2WI上呈稍高信号，T1WI上呈低信号，增强后呈渐进性强化。结论：局灶性肝紫癜的主要CT表现为肝内边界模糊的低密度病灶，增强扫描呈渐进性强化。     

明显强化孤立肺结节血流模式的临床价值

目的利用4层螺旋CT动态增强技术定量评价不同性质的明显强化孤立肺结节的血流模式并初步评价血管内皮生长因子(VEGF)表达阳性的孤立性肺腺癌血管生成与血流模式定量CT参数的相关性.方法 78例孤立明显强化肺结节(直径≤4 cm,68例恶性,10例活动性炎性),行多层螺旋CT(MSCT)动态增强(以4 ml/s的流率注入对比剂).记录孤立肺结节增强前后各时相的CT值并计算强化值、灌注值,结节-主动脉强化值比.灌注值等于时间-密度曲线最大斜率除以主动脉强化值.其中30例VEGF表达阳性的肺腺癌患者用免疫组织化学测定微血管密度(MVD)并标定VEGF,评价肺腺癌血流模式定量CT参数(强化值、灌注值、结节-主动脉强化值比及平均通过时间)与MVD的相关性.结果恶性结节强化值(35.79±10.76) HU与活动性炎性结节(39.76±4.59) HU差异无显著意义 (t=1.148 , P=0.255).恶性结节的结节-主动脉强化值比(14.27±4.37)%及灌注值(3.02±0.96)ml-1·min-1·kg-1均低于活动性炎性结节(18.51±2.71)%,(6.34±4.39)ml-1·min-1·kg-1 (t=2.978,P=0.004;t=5.590,P<0.0001).VEGF表达阳性的肺腺癌强化值(33.06±13.57)HU、结节-动脉强化值比(14.25±4.92)%及灌注值(2.97 ±0.56) ml-1·kg-1·min-1与MVD(70.15±20.03)条/视野,均呈正相关性(r=0.781, P<0.0001;r=0.688, P<0.0001;r=0.716, P<0.0001).平均通过时间(14.86±5.84)s与MVD无显著相关性(r=0.260, P=0.200).结论恶性与活动性炎性孤立肺结节血流模式不同,恶性结节通过结节-大动脉强化值比和灌注值可有效区别于活动性炎性结节,有助于两者鉴别诊断.肺腺癌强化值、结节-动脉强化值比及灌注值反映了VEGF表达阳性的肺腺癌的MVD.强化值、结节-动脉强化及灌注值可作为VEGF相关的肺腺癌血管生成的指标.     

2种磁共振对比剂动态增强扫描对肝内结节的鉴别诊断价值

目的：探讨钆喷酸葡胺(Gd-DTPA)及钆塞酸二钠(Gd-EOB-DTPA)的磁共振动态增强扫描对肝脏结节的鉴别诊断价值。方法回顾性分析60例经 Gd-DTPA 及 Gd-EOB-DTPA 增强的肝内结节磁共振平扫、多时相动态增强扫描图像。结果所有入组病例经 Gd-DTPA 动态增强扫描后,19例患者诊断为原发性肝细胞癌,并经病理证实;8例确诊为肝转移瘤;18例诊断为肝内良性结节,随访3~6个月结节大小无明显变化。15例鉴别诊断困难的患者行 Gd-EOB-DTPA 多时相动态增强扫描,4例动脉期明显强化,门脉期强化程度迅速下降,平衡期轻度强化,肝特异性期与正常肝实质比较呈等信号,后证实为肝腺瘤;7例动脉期轻到中度强化,门脉期强化程度下降,平衡期强化不明显,肝特异性期与正常肝实质比较呈低信号,经随访或病理确诊为肝细胞癌;3例动脉期表现为轻度强化,门脉期及平衡期略强化,肝特异性期与正常肝实质比较呈低信号,根据其病史诊断为转移瘤;1例动脉期病变周边明显强化,门脉期强化程度迅速下降,平衡期轻度强化,肝特异性期与正常肝实质比较呈等信号,病变中心始终呈低信号,经复查诊断为肝良性病变。结论Gd-DTPA 动态增强 MRI 扫描对诊断肝内结节性病灶具有重要作用,Gd-EOB-DTPA 在鉴别结节的良恶性方面具有较大优势。     

肝细胞癌多项MRI表现与癌细胞核DNA含量的多元线性回归分析

目的 探讨肝细胞癌（hepatocellular carcinoma,HCC）多项MRI表现与癌细胞核DNA含量及病理学表现的相关性。资料与方法 分析经手术及病理证实的43例HCC患者。根据肿瘤动态强化特征分为4型（Ⅰ型：肿瘤信号动脉期高于或等于肝实质,门脉期低于肝实质;Ⅱ型：肿瘤信号动脉期和门脉期均高于或等于肝实质;Ⅲ型：肿瘤信号动脉期低于肝实质,门脉期高于或等于肝实质;Ⅳ型：肿瘤信号动脉期和门脉期均低于肝实质）。同时观察动脉期肿瘤边缘强化情况、肿瘤强化方式和强化程度、大小、包膜、坏死、肝内子灶、门脉瘤栓。采用流式细胞仪（flow cytometry,FCM）测定石蜡包埋肿瘤标本的癌细胞核DNA含量,得出DNA指数（DNA index,DI）。分析MRI表现与DNA含量间的关系。结果 43例中Ⅰ型强化29例,Ⅱ型12例,Ⅲ型及Ⅳ型各1例。Ⅰ型强化HCC的DI显著高于Ⅱ型（P=0．009）。动脉期肿瘤边缘强化与非边缘强化间（P=0．005）、明显强化与轻度强化间（P=0．038）、强化不均匀与强化均匀间（P〈0．001）DI有统计学差异。肿瘤直径弓5cm、无包膜、有瘤内坏死、子灶或瘤栓,其DI明显高于肿瘤直径〈3cm（P=0．002）、有包膜（P=0．027）、无瘤内坏死（P=0．026）、无子灶或瘤栓（P=0．005）。肿瘤直径〈3cm与3．5cm间（P=0．192）以及3．5cm与〉5cm间（P=0．084）DI无统计学意义。经多元线性回归分析,肿瘤大小、包膜、动脉期强化方式、强化类型与DI相关,回归方程为：Y=-1．678＋0．279X1＋0．534X2＋0．668X3＋0．427X4。病理为Ⅲ、Ⅳ级的肿瘤DI明显高于Ⅰ、Ⅱ级（P=0．001）。结论 HCC多项MRI表现与癌细胞核DNA含量及病理分级有相关性,可在一定程度上间接反映HCC的恶性生物学行为,为临床选择治疗方案及评价预后提供信息。     

CT灌注成像评价肝细胞癌TACE前后血供的初步经验

目的:探讨经导管动脉化疗栓塞术(TACE)治疗肝细胞癌(HCC)前后血流灌注变化。材料和方法:对21例HCC患者TACE治疗前、后1个月行CT灌注成像扫描,测量肿瘤组织治疗前后肝动脉灌注值(HAP)、门静脉灌注值(HPP)及肝动脉灌注指数(HPI)。结果:治疗前7例肿瘤组织肝动脉灌注图呈均匀高灌注,14例呈不均匀高灌注,液化坏死区无血流灌注。门静脉灌注图,20例呈低灌注,1例无血流灌注。TACE后肿瘤组织HAP及HPI显著减少,HPP无明显变化。5例病灶碘油完全充填,16例病灶部分区域碘油充填,碘油区无血流灌注,肿瘤残留区仍有血流灌注。结论:CT灌注成像为评价TACE疗效提供了一个新方法。     

肝硬化多层螺旋CT灌注成像临床研究

目的采用多层螺旋CT对肝脏进行灌注成像,探讨肝硬化严重程度不同时血流灌注参数变化的规律。方法对28例肝功能Ch ild-Pugh分级不同的肝硬化患者以及20例对照者选取肝门区良好显示脾脏、门脉主干、肝左右叶的层面,进行CT双层动态增强扫描,绘制时间-密度曲线,计算肝脏灌注参数。结果正常组肝动脉灌注量(HAP)为(0.3384±0.1409)m l.m in-1.m l-1,门脉灌注量(PVP)为(1.1063±0.3571)m l.m in-1.m l-1,总肝灌注量(THBF)为(1.4449±0.4633)m l.m in-1.m l-1,肝动脉灌注指数(HAI)为(23.37±6.12)%。肝硬化严重程度不同时,Ch ild-Pugh A、B、C 3组肝动脉灌注量均较正常组增高,但组间呈逐渐下降的趋势(0.4714±0.1657,0.4521±0.1019,0.4401±0.8209)m l.m in-1.m l-1;门脉灌注量和总肝灌注量均较正常组下降,组间呈下降的趋势,分别为(0.9403±0.1882,0.8362±0.1607,0.7365±0.1235)m l.m in-1.m l-1;(1.4148±0.3367,1.2884±0.2315,1.1766±0.1705)m l.m in-1.m l-1;动脉灌注指数则较正常组逐级升高(30.48±4.93,35.04±5.01,37.37±4.38)%。结论多层螺旋CT可以准确地测量肝脏的血流灌注参数,肝硬化肝脏血流灌注参数的变化与疾病的严重程度相关。     

微小肝细胞癌（≤1cm）的钆塞酸二钠增强MRI表现分析

【摘要】目的：探讨微小肝细胞癌（HCC）的钆塞酸二钠增强MRI表现。方法：回顾性分析125个经病理证实为微小HCC（≤1cm）的钆塞酸二钠增强MRI特征,并比较不同MR序列对微小HCC的检出率。结果：125个微小HCC中,116个（92.8%）DWI与T2WI呈高信号,112个（89.6%）T1WI呈低信号,31个（24.8%）病灶内含脂质,102个（81.6%）动脉期高强化,86个（68.8%）门脉期为低信号,112个（89.6%）过渡期呈低信号,80个（64.0%）可见强化包膜,122个（97.6%）肝胆特异期呈低信号。动态增强67个（53.6%）呈“快进快出”,25个（20.0%）呈“快进慢出”,21个（16.8%）呈相对乏血供,12个（9.6%）呈持续强化。肝胆特异期对微小HCC的检出率（97.6%）高于T1WI（89.6%,P=0.01）、动脉期（81.6%,P<0.01）、门脉期（68.8%,P<0.01）、过渡期（89.6%,P<0.01）及“快进快出”强化（53.6%,P<0.01）。结论：微小HCC钆塞酸二钠增强MRI表现各异,其肝胆特异期结合DWI有助于微小HCC的诊断。     

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.