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81.
Yasuyuki Yamashita Katsuhiko Mitsuzaki Yi Tang Tomohiro Namimoto Mutsumasa Takahashi 《Journal of magnetic resonance imaging : JMRI》1997,7(4):623-628
MR angiography (MRA) was performed in 50 consecutive subjects (mean age, 59 years), who had been referred for abdominal MRA, on a 1.5-T superconductive unit that used a body phased-array coil. Three breath-hold three-dimensional sequences were evaluated both in phantom and clinical studies: (a) standard fast three-dimensional gradient-echo sequence (TR = 15, TE = 6; imaging time, 32 seconds), (b) ultrafast three-dimensional gradient-echo sequence (TR = 8.2, TE = 3; imaging time, 18 seconds), and (c) ultrafast magnetization-prepared (MP) rapid acquisition gradient echo (RAGE) (TR = 5.8, TE = 2.9, inversion time [TI] = 20; imaging time, 15 seconds). The initial 30 patients were randomized into three groups by three separate sequences. For the remaining 20 patients, ultrafast-gradient-echo and ultrafast MP-RAGE sequences were performed. Conventional angiography was performed on 36 patients. Signal measurements of the phantom and clinical images of the aorta, visceral branches of the aorta, iliac arteries, inferior vena cavae, and portal veins were performed. The overall image quality and background fatty tissue contrast of the vessels were rated subjectively. Comparison of images between MRA and conventional angiography also was performed. The contrast between the vessels and background fatty tissue was significantly higher in the ultrafast MP-RAGE sequence in both quantitative and qualitative analysis, and image-quality ultrafast MP-RAGE was superior to the other two sequences (P < .01). The aorta and iliac arteries could be visualized in all pulse sequences, and abnormalities of these vessels were diagnosed correctly. The renal artery was visualized more clearly with the two ultrafast sequences. 相似文献
82.
S Kimel L O Svaasand M Hammer-Wilson V Gottfried S Cheng E Svaasand M W Berns 《Lasers in surgery and medicine》1992,12(4):432-440
The chick chorioallantoic membrane (CAM) model was used to study vascular effects of photodynamic therapy (PDT) and hyperthermia (HPT) and the synergism of these modalities. The CAM is a convenient medium for monitoring the modifications of the vasculature. It is possible to view the CAM and to examine structural changes of individual blood vessels in real time. Moreover, the CAM is a closed system which lends itself to mathematical modeling of the temporal and spatial temperature profile and in which HPT can be performed quantitatively and to a selected depth, using different lasers. A porphyrin-type photosensitizer solution was applied to areas of the CAM, defined by teflon O-rings placed on the surface. Uptake dynamics of the sensitizer into the CAM was determined by analyzing its fluorescence in vivo. The CAM area was irradiated with a dual-wavelength laser system composed of a dye laser at 644 nm (to induce PDT) and a CO2 laser at 10.6 microns (to bring about HPT). Damage to the CAM vasculature, due to combined PDT+HPT, was compared to the outcome of the separate modalities, and a synergistic effect of about 40% was observed. 相似文献
83.
Rolf Gronas B. Eng Peter G. Kalman MD Daryl S. Kucey MD Graham A. Wright PhD 《Journal of magnetic resonance imaging : JMRI》1997,7(4):637-643
Flow-independent angiography (FIA), an approach that isolates arterial blood using MR relaxation characteristics rather than flow effects, was evaluated for application in peripheral vascular disease (PVD). First, pilot studies were conducted in which FIA coronal projection images were obtained from controls and symptomatic patients with PVD to assess clinical utility. All control images corresponded to the expected leg arterial anatomy with little interference from deep veins (one of five) and muscle (zero of five). Superficial venous signal was less well suppressed in comparison to deep veins (four of five). Images of symptomatic patients were less consistent with difficulty suppressing muscle and deep venous signal in some cases and edema when present. We then compared T2 values for muscle (T2m, tibialis anterior), arterial blood (femoral and popliteal arteries), and venous blood (femoral, popliteal, and saphenous veins) in controls (n = 8) and symptomatic patients with intermittent claudication (n = 5) or ischemic rest pain (n = 7). Changes in T2 measurements of various tissues accounted for poorer contrast in symptomatic patients. Patients with ischemic rest pain had significantly higher T2m compared with controls (T2m = 39.3 ± 2.1 (1 standard error of the mean [SEM]) versus 30.9 ± .4, P < .01). For all measurements, other than saphenous vein, variances were greater in symptomatic patients. To realize the inherent advantages of FIA for this clinical application, additional work on suppression of signals from muscle, veins, and edema is required. One promising approach involves shifting from projection images to three-dimensional acquisitions for improved tissue suppression. 相似文献
84.
A postal survey of 100 hospitals throughout the United Kingdom and Ireland was conducted to assess current practice in the pre-operative assessment and use of pulmonary artery catheters in patients undergoing elective abdominal aortic aneurysm repair. Seventy-four completed questionnaires were received. The survey revealed that 53% of respondents hold designated pre-operative assessment clinics, attended by anaesthetists in 54% and cardiologists in 26%. However, only 4% of respondents have a written protocol for stratifying patients and assessing peri-operative risk. By far the commonest investigation of choice for further cardiological assessment is transthoracic echocardiography (67%). Other investigations of choice are multiple update gated acquisition (MUGA) scan (13%), dipyridamole thallium imaging (9%), exercise ECG (6%), stress echocardiography (1%) and stress MUGA (1%). Two units (3%) never undertook further investigation. Pulmonary artery flotation catheters are used as a routine by 9% of respondents, dependent upon left ventricular ejection fraction by 65%, dependent on other factors by 7% and not used at all by 19%. The survey reveals widespread variation in pre-operative assessment of patients undergoing elective repair of abdominal aortic aneurysm. 相似文献
85.
胰岛素对大鼠血管平滑肌细胞表型转化的影响 总被引:2,自引:0,他引:2
目的:探讨胰岛素对体外培养的血管平滑肌细胞(vascular smooth muscle cell,VSMC)表型转化的影响.方法:用酶消化法分离大鼠VSMC,采用免疫组织化学法检测胰岛素作用后VSMC肌动蛋白(α-SM actin),RT-PCR 检测胰岛素作用后VSMC中bFGF、TGF-β、PDGF、matrix Gla和OPN各目的基因mRNA相对表达水平.结果:胰岛素组VSMC的3H-TdR掺入值比对照组升高47%(P<0.01), VSMC α- SM actin免疫组化结果显示对照组的α-SM actin比胰岛素组染色深.而matrix Gla和OPN在培养的VSMC中mRNA的表达量,胰岛素组明显高于对照组(P<0.05),同时bFGF、TGF-β、PDGF的表达胰岛素组也明显高于对照组(P<0.05).并可明显见到细胞骨架F-actin、G-actin重新分布.结论:在合成表型的matrix Gla和OPN表达量明显高于收缩表型,而合成表型的α- SM actin表达量明显低于收缩表型.提示胰岛素对VSMC的表型转化起了一定作用.胰岛素在促进了VSMC增殖的同时,伴有VSMC由收缩型转变为合成型及细胞骨架F-actin、G-actin重新分布. 相似文献
86.
烧伤大鼠血清对血管内皮细胞通透性的影响 总被引:4,自引:2,他引:2
加深入阐明严重烧伤早期全身血管通透性增加继而引直民早期损害的发生机制,本实验应用培养于微孔滤膜上的小牛瞌 及皮细胞单层所构成的选择性通透屏障模型,观察了30%Ⅲ度烧伤大鼠血清对其影响,结果发现,烧伤早期烧伤血清刺激后EC单层对Hanks液或白蛋白液滤过流量、滤过系数均明显增加。 相似文献
87.
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90.
组织工程化血管的种子细胞在体外培养扩增方法的实验性研究 总被引:3,自引:2,他引:1
目的为培养组织工程化血管的实验研究提供细胞来源.方法采用酶消化法和组织块法培养人脐静脉血管内皮细胞、人脐动脉血管平滑肌细胞及成纤维细胞,并进行细胞的传代、纯化、鉴定以及形态学观察.结果培养细胞符合血管内皮细胞、血管平滑肌细胞及成纤维细胞的各有形态特征.结论所培养的细胞有望作为体外构建组织工程化血管的应用. 相似文献