大剂量对比剂团注在MRI检查中应用

目的：探讨大剂量对比剂注射器团注在脑转移瘤及其血管成像中的临床意义。方法：对35例脑转移瘤患者行MR平扫和增强扫描作为对照，其中26例脑转移瘤患者增强扫描分别采用单剂量手推方式注射(10ml和大剂量注射器团注，并对图像做对比分析。对22例体部血管病变患者和15例肝、肾移植患者及供体行常规扫描后的增强血管成像(enhancedMRA)。快速大剂量团注(20～40ml扫描以1．5～3ml／s流率经上肢大静脉注射造影，造影前根据病灶和血管大小，首先预设置流率、流量及注射时间，再对所选择的病变区域或血管行快速动态扫描和延迟扫描。结果：35例均已确诊有原发病灶的脑转移瘤忠者中23例经手术病理证实，12例经活检病理证实。19例体部血管病变经DSA证实。所有检查均获成功，且大剂量注射器团注组对病变显示优于小剂量手推组。结论：大剂量的注射冕团注能更清晰显示病灶数目和病灶大小、数目和病灶内钙化、坏死以及供给血管情况，为临床提供精确的诊断。     

磁共振高压注射器在磁共振血管成像中的应用及护理

目的：评价高压注射器在磁共振血管成像中的临床应用价值及护理。材料和方法：对50例病人行磁共振血管成像增强扫描。使用高压注射器经上肢大静脉进行快速大剂量对比团注。造影前预先设置流速、流量及注射时间。结果：50例磁共振血管成像均获成功。结论：磁共振高压注射器可保持足够快的流速和流量。使磁共振血管造影效果满意。     

3.0T磁共振全心冠状动脉成像对冠心病的诊断价值

目的 探讨3.0T磁共振对比剂增强的全心冠状动脉成像在冠心病诊断中的价值.方法 对51例冠心病患者行心脏磁共振检查,包括自由呼吸门控下的全心增强冠状动脉成像、静息心肌灌注和心肌延迟强化成像.结果 本组51例患者中46例成功完成了全心增强冠状动脉成像.在以患者为基础的分析中,全心磁共振血管造影(MRCA)诊断冠状动脉显著...     

多层CT灌注成像技术在脑肿瘤诊断中的应用

目的：探讨多层螺旋CT灌注扫描成像技术在脑肿瘤诊断中的应用价值。方法：收集2004．11—2006．1月辽宁医学院附属第一医院脑肿瘤住院患者43例，对所有患者行普通CT扫描、增强CT扫描及CT灌注成像。首先对患者行普通CT扫描及增强CT扫描，以平扫最大肿瘤层面为中心行灌注检查，应用“Toggling—table”技术行CT灌注扫描取得数据用Per-fusion3软件中的Brain tumor灌注分析软件进行分析。结果：本研究中普通CT、增强CT及CT灌注成像均能清晰地显示病变，但CT灌注成像能够获得更多的病变信息资料，获得的脑肿瘤区域的CBF、CBV、PS灌注图，PS图像可以清晰显示肿瘤区与水肿区及肿瘤的血管通透性。结论：多层CT灌注成像可以快速、简捷、清晰的显示出脑肿瘤的大小与轮廓，且灌注成像对在体观察脑肿瘤血流状态及肿瘤血管功能提供了一种新的方法。     

CT脑组织血流灌注成像方法的研究

目的 探讨CT灌注成像方法在颅脑疾病诊断中的初步临床应用。方法 采用Siemens Plus4和Perfusion CT/VA 10A扫描灌注系统,对8例进行常规扫描,然后选定基底节区层面做快速注药后的动态CT检查,对比剂为优维显300（300mgI/ml),注射速度10ml/s,剂量50ml,经高压注射器注射的同时进行扫描,共扫描32层。经后处理获得一系列反映不同时相的脑血流灌注图,然后进行综合分析。结果 4例正常脑血流灌注图清晰,脑灰白质交界分明、对称,染色均匀;2例缺血灌注图经伪彩染色后,病灶显示更加直观、清晰;2例肿瘤灌注图显示单发转移瘤异常供血血管、水肿区和过度灌注区。结论 快速注射对比剂和选用上矢状窦为参照血管计算脑血容量是获得高质量灌注图像的保证,为实现CT脑组织血流灌注的定量研究提供了新的方法。     

多层螺旋CT灌注成像在脑肿瘤中的应用研究

目的评价多层螺旋CT灌注扫描成像技术在脑肿瘤中的应用价值。资料与方法43例脑肿瘤患者于术前1周及术后出院时行常规CT扫描、CT灌注成像及增强扫描。数据应用CT工作站Perfusion3软件分析,获得脑血流量（CBF）图、血容量（CBV）图、对比剂平均通过时间（MTT）图和表面渗透性（PS）图。结果所有灌注图像均可清晰地显示肿瘤的大小与轮廓且能定量测定肿瘤组织的灌注状态。结论多层CT灌注成像为在体观察脑肿瘤血流状态及肿瘤血管功能提供了一种新的方法,对研究脑肿瘤的生物学特性,鉴别诊断及预后判断有一定的价值。     

磁共振灌注成像在急性心肌梗死诊断中的价值

目的研究磁共振灌注成像在急性心肌梗死诊断中的价值。方法使用1.5T超导型磁共振扫描仪,对29例经临床诊断的急性心肌梗死病人行灌注成像,其中17例进行冠状动脉造影术,全部病例通过AW4.0工作站处理,计算出首过时间及首过最大上升斜率,同时测定正常心肌与心室腔的首过时间及最大上升斜率。对比剂总量20ml,注射流率首过3ml/s,共9ml,以后以1ml/s注射。结果29例心肌梗死病例显示延迟病灶明显强化及首过最大上升斜率降低,28例首过时间延迟,17例行冠状动脉造影,14例发现冠状动脉狭窄,未发现冠状动脉狭窄的3例,均为心内膜下或心外膜下梗死。结论急性心肌梗死MR灌注成像具有特征性表现。     

磁共振TRICKS技术在下肢血管成像的临床应用价值

目的：探讨3．0T磁共振的时间分辨对比剂动态显像技术（TRICKS）在下肢血管成像中的应用价值。方法：对21例下肢血管疾病患者（肿瘤病变10例,血管性病变11例）行常规MRI平扫,注入对比剂后应用TRICKS技术行动态血管造影,最后行常规增强扫描,分析全部病例的图像质量和病变显示情况并与手术病理或DSA对照。结果：所有病例均顺利完成TRICKS检查,TRICKS图像动态显示了动静脉的充盈情况和动脉结构,肿瘤性病变可以清晰显示肿瘤的供血血管,血管性病变可以直观显示出畸形或迂曲的血管,所有诊断与DSA和病理诊断相符。结论：TRICKS技术是一种新的、有效的腹部至下肢血管成像方法,能够在不影响常规增强扫描的情况下动态观察血管情况,对下肢血管病变的诊断具有重要价值。     

儿童主动脉梗阻性病变的磁共振诊断

目的：报道93例儿童梗阻性主动脉病变并评价其磁共振成像技术。方法：主要采用造影增强磁共振血管成像术(CEMRA)诊断儿童梗阻性主动脉病变。结果：93例中，主动脉缩窄67例，主动脉弓离断l6例，主动脉瓣上狭窄2例，大动脉炎8例。男62例，女3l例。82例经手术或心血管造影检查证实磁共振诊断正确率为97．5％。结论：造影增强磁共振血管成像术是很好的儿童梗阻性主动脉病变诊断手段。     

3D DCE-MRA对下肢动脉疾病的诊断价值

本文介绍采用三维动态增强磁共振血管成像技术经静脉快速注射顺磁性对比剂,智能追踪对比剂到达靶血管的峰值时间,快速梯度序列行下肢动脉扫描,配合后处理得到良好的下肢动脉三维血管树的方法。作为一种具有无辐射、无创伤、并发症少、成像速度快、空间分辨率高、扫描范围大等明显优势的新型影像学检查技术,三维增强磁共振血管成像可以满足诊断下肢动脉疾病的临床要求,并易被患者接受有较高价值。     

Cerebral hemodynamics on MR perfusion images before and after bypass surgery in patients with giant intracranial aneurysms.

BACKGROUND AND PURPOSE: Preoperative assessment of the anatomy and dynamics of cerebral circulation for patients with giant intracranial aneurysm can improve both outcome prediction and therapeutic approach. The aim of our study was to use perfusion MR imaging to evaluate cerebral hemodynamics in such patients before and after extraintracranial high-flow bypass surgery. METHODS: Five patients with a giant aneurysm of the intracranial internal carotid artery underwent MR studies before, 1 week after, and 1 month after high-flow bypass surgery. We performed MR and digital subtraction angiography, and conventional and functional MR sequences (diffusion and perfusion). Surgery consisted of middle cerebral artery (MCA)-internal carotid artery bypass with saphenous vein grafts (n = 4) or MCA-external carotid artery bypass (n = 1). RESULTS: In four patients, MR perfusion study showed impaired hemodynamics in the vascular territory supplied by the MCA of the aneurysm side, characterized by significantly reduced mean cerebral blood flow (CBF), whereas mean transit time (MTT) and regional cerebral blood volume (rCBV) were either preserved, reduced, or increased. After surgery, angiography showed good canalization of the bypass graft. MR perfusion data obtained after surgery showed improved cerebral hemodynamics in all cases, with a return of CBF index (CBFi), MTT, and rCBV to nearly normal values. CONCLUSION: Increased MTT with increased or preserved rCBV can be interpreted as a compensatory vasodilatory response to reduced perfusion pressure, presumably from compression and disturbed flow in the giant aneurysmal sac. When maximal vasodilation has occurred, however, the brain can no longer compensate for diminished perfusion by vasodilation, and rCBV and CBFi diminish. Bypass surgery improves hemodynamics, increasing perfusion pressure and, thus, CBFi. Perfusion MR imaging can be used to evaluate cerebral hemodynamics in patients with intracranial giant aneurysm.     

烟雾病的MRI和MRA诊断

分析和讨论烟雾病的ＭＲＩ和ＭＲＡ表现及其诊断意义。材料和方法：对９例烟雾病患者进行了ＭＲＩ和ＭＲＡ检查,其中２例进行了ＤＳＡ检查。结果：９例ＭＲＩ上,８例显示脑实质改变包括脑梗死５例,脑萎缩２例,脑室扩大１例。８例中４例显示异常血管流空现象。另１例脑内未见异常．ＭＲＡ均良好地显示了病变血管狭窄和闭塞现象,表现为多支、双侧受累,在大脑中动脉为主,与ＤＳＡ所见相仿。结论：ＭＲＩ结合ＭＲＡ可作为烟雾病诊     

The magnetic resonance Matas test: Feasibility and comparison with the conventional intraarterial balloon test occlusion with SPECT perfusion imaging

PURPOSE: To evaluate a new MR Matas test that uses a form of contrast-enhanced MR angiography (MRA) with temporary manual occlusion of the common carotid artery whose internal carotid artery (ICA) is to be permanently sacrificed. MATERIALS AND METHODS: The MR Matas test was performed on eight patients using an open type MR imager (Signa Profile 0.2 Tesla ver. 7.5, GE-YMS, Tokyo, Japan). Conventional balloon occlusion Matas test and single-photon emission computed tomography (SPECT) of the brain were performed in all cases within a week before or after the MR Matas test. RESULTS: The MR Matas test was successful in all eight patients without any complications. The image quality of the MR Matas test was generally sufficient to confirm cross-flow from the patent side to the occluded side in comparison with selective intraarterial digital subtraction angiography (IADSA) except in one case. CONCLUSION: Brain perfusion information using MR Matas test is comparable to brain SPECT.     

Gd—DTPAMRI在心绞痛中的作用

目的：探讨Ｇｄ－ＤＴＰＡ增强ＭＲＩ在心绞痛中的作用。材料和方法：２２例心绞痛作Ｇｄ－ＤＴＰＡ增强前后ＭＲＩ检查,其中１６例作冠状动脉造影检查,１１例作ＳＰＥＣＴ检查。结果：增强ＭＲＩ上,１８例（８２％）可见局部异常强化信号,其部位与临床ＥＣＧ吻合,与ＣＡ、ＳＰＥＣＴ所示心肌缺血部位一致。在ＭＲＩ上的异常强化信号与冠状动脉狭窄、ＳＰＥＣＴ显示灌注缺损密切有关。结论：Ｇｄ－ＤＴＰＡＭＲＩ为心绞痛的诊断提供有价值的依据。     

Effect of vascular stenosis on perfusion-weighted imaging; differences between calculation algorithms

PURPOSE: To determine the most suitable postprocessing technique for magnetic resonance (MR) perfusion imaging in patients with vascular stenosis, by comparing the cerebral blood flow (CBF) maps of single photon emission tomography (SPECT) and perfusion MR imaging (MRI). MATERIALS AND METHODS: In 15 consecutive patients (14 men and one woman, mean age 73.9 +/- 6.0 years) with stenosis of common carotid artery (CCA) or internal carotid artery (ICA) of more than 75%, both brain perfusion MRI and brain perfusion SPECT were performed. From perfusion MR images, CBF maps were calculated with the first moment, singular value decomposition (SVD), and block circulant SVD (b-SVD) methods, and CBF maps from each algorithm were compared with those from SPECT. RESULTS: The b-SVD method had the best correlation with SPECT (R = 0.814), followed by the first moment method (R = 0.776) and the SVD method (R = 0.723). The b-SVD method has the least mean difference with SPECT (0.118), the first moment method also had less difference (0.121), and the SVD had greatest mean difference (0.164). CONCLUSION: Our results suggest that in patients with vascular impairment the b-SVD method will be the technique of choice rather than SVD or first moment method.     

Surveillance of peripheral arterial bypass grafts with three-dimensional MR angiography: comparison with digital subtraction angiography

OBJECTIVE. The purpose of this study was to use contrast-enhanced three-dimensional MR angiography to assess the patency of peripheral arterial bypass grafts of the lower extremity. SUBJECTS AND METHODS. The study included 39 patients with 45 lower limb grafts. Twenty-eight were saphenous vein grafts, 13 were expanded polytetrafluoroethylene, and two were Dacron grafts. Digital subtraction angiography correlation was available for 30 patients (31 grafts). MR angiography was performed on a 1.5-T system with a multichannel quadrature phased array peripheral vascular coil. The scanning delay was determined with a test bolus technique, using half-time to maximum signal intensity in the graft. Arterial imaging was accomplished with two three-dimensional MR angiography acquisitions with gadopentetate dimeglumine administered using an automated injector. The pelvic and femoral arteries were imaged, the MR table was repositioned, and the lower limb arteries were imaged. The three-dimensional MR angiography sequence used the following parameters: TR/TE, 5.2/1.5 msec; inversion time, 28 msec; flip angle, 30 degrees. The proximal anastomosis, graft, and distal anastomosis were characterized as normal, stenosed, occluded, or ectatic or aneurysmatic. RESULTS. Sensitivity and specificity values for MR angiography regarding the assessment of grafts were 100% for 87 evaluable segments for which digital subtraction angiography correlation was available: stenosis (n = 10), occlusions (n = 9), ectasia or aneurysms (n = 8). Six segments could not be assessed because of the presence of intravascular stents or metallic clips. CONCLUSION. Contrast-enhanced three-dimensional MR angiography is well suited for the characterization of arterial grafts, for planning subsequent vascular interventions, and for excluding further lesions.     

Time-resolved contrast-enhanced MR angiography of intracranial lesions

PURPOSE: To determine if contrast-enhanced (CE) MRI of intracranial lesions benefits from time-resolved MR angiography (MRA) during contrast agent injection. MATERIALS AND METHODS: For 126 patients with suspected intracranial lesions undergoing routine CE MRI at 3.0T (N = 88) or 1.5T (N = 38), time-resolved CE MRA (three-dimensional [3D] time-resolved imaging of contrast kinetics [TRICKS]) was performed during injection of the routine gadolinium (Gd) dose of 0.1 mmol/kg. Time to peak (TTP) enhancement of lesions as well as time to internal carotid artery (ICA), middle cerebral artery (MCA), superior sagittal sinus (SSS), and jugular vein enhancement were measured. Source and maximum intensity projection (MIP) images were reviewed to delineate the spatial relationship of lesions and the vasculature. RESULTS: In 61 patients (48%), additional important findings were detected on time-resolved MRA that were not seen on the routine CE protocol, including aneurysms (N = 6), arteriovenous malformations (N = 7), ICA stenoses (N = 2), vascular anomalies (N = 18), and relationships between lesions and vessels (N = 28). In addition, tumor TTP correlated with glioma grade (r = 0.87) and discriminated epithelial from nonepithelial meningiomas (P = 2.6 x 10(-5)). MRA added eight minutes to the total exam time. CONCLUSION: Time-resolved MRA performed during contrast agent injection adds information to the routine brain CE MRI examination of intracranial lesions with only a small time penalty and no additional risk to the patient.     

急性缺血再灌注心肌磁共振成像实验研究

目的：通过MR灌注成保评价急性梗死心肌组织血流灌注特点。方法：采用结扎左前降支90min存灌注的方法建立为存灌注梗死心肌组，对6只犬行MRI灌注成保及延迟扫描，观察犬心肌缺血存灌注模型梗死心肌MRI特点。结果：犬心肌缺血存灌注梗死心肌MR灌注成保表现为灌注缺损区，延迟扫描表现为高信号。结论：MR灌注成保有助于评价心肌血流，诊断心肌缺血存灌注梗死心肌。     

MR Diagnosis of a Pulmonary Embolism: Comparison of P792 and Gd-DOTA for First-Pass Perfusion MRI and Contrast-Enhanced 3D MRA in a Rabbit Model

Objective

To compare P792 (gadomelitol, a rapid clearance blood pool MR contrast agent) with gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA), a standard extracellular agent, for their suitability to diagnose a pulmonary embolism (PE) during a first-pass perfusion MRI and 3D contrast-enhanced (CE) MR angiography (MRA).

Materials and Methods

A perfusion MRI or CE-MRA was performed in a rabbit PE model following the intravenous injection of a single dose of contrast agent. The time course of the pulmonary vascular and parenchymal enhancement was assessed by measuring the signal in the aorta, pulmonary artery, and lung parenchyma as a function of time to determine whether there is a significant difference between the techniques. CE-MRA studies were evaluated by their ability to depict the pulmonary vasculature and following defects between 3 seconds and 15 minutes after a triple dose intravenous injection of the contrast agents.

Results

The P792 and Gd-DOTA were equivalent in their ability to demonstrate PE as perfusion defects on first pass imaging. The signal from P792 was significantly higher in vasculature than that from Gd-DOTA between the first and the tenth minutes after injection. The results suggest that a CE-MRA PE could be reliably diagnosed up to 15 minutes after injection.

Conclusion

P792 is superior to Gd-DOTA for the MR diagnosis of PE.     

Evaluation of tissue perfusion in a rat model of hind-limb muscle ischemia using dynamic contrast-enhanced magnetic resonance imaging

PURPOSE: To evaluate the feasibility of using dynamic contrast-enhanced magnetic resonance imaging (MRI) for assessment of muscle perfusion in a rat model of hind-limb ischemia. MATERIALS AND METHODS: The acute alteration and chronic recovery in muscle perfusion and perfusion reserve after femoral artery ligation were quantified using the maximum Gd-DTPA uptake rate obtained by a T(1)-weighted gradient-recalled echo sequence. Radionuclide-labeled microsphere blood flow measurements were performed for comparison with the MR perfusion measurement on a separate set of animals. RESULTS: After femoral artery ligation, a significant reduction in resting muscle perfusion was only observed at 1 hour post-ligation during the 28-day follow-up period. Muscle perfusion reserve was severely diminished following the ligation. Despite significant recovery over time, perfusion reserve to the ligated limb reached only 63% of the perfusion capacity in the unaffected limb by 42 days post ligation. A strong correlation (r = 0.86) between MR perfusion and microsphere blood flow measurements was observed for evaluation of relative changes in muscle perfusion. CONCLUSION: Dynamic contrast-enhanced MRI with Gd-DTPA is useful to assess time-dependent changes in muscle perfusion and perfusion reserve in this hind-limb ischemia model.