大鼠放射性脑损伤的MRS、PWI研究

目的研究大鼠放射性脑损伤不同时期的MRS、PWI表现,为其早期诊断提供依据。方法将成年大鼠30只随机分为对照组和照射组,照射前均行MRI、MRS及PWI检查。照射组分别于照射后1、3、6、9及12个月行MRI、MRS及PWI检查,计算NAA/Cr和Cho/Cr比值,测量灌注后大鼠双侧侧脑室周围的rCBV值。结果 1各照射组大鼠的NAA/Cr比值与对照组相比逐渐下降,差异均有统计学意义(P0.05);照射后Cho/Cr比值先上升,3个月时达峰值,随后逐渐下降,6个月内各组的Cho/Cr与对照组相比有统计学意义(P0.05);2照射1个月后各组的rCBV值均明显低于对照组,差异有统计学意义(P0.05)。结论 MRS及PWI能在放射性脑损伤发生形态学改变之前检测出脑组织代谢及灌注异常,为放射性脑损伤的早期诊断提供依据。     

CT灌注技术对脑血流分布的初探

目的 :改进灌注成像技术 ,对大脑不同区域血流分布的差异作初步探索。方法 :2 0例无运动系统或基底节区病变受检者行基底节层面灌注扫描。通过高压注射器团注对比剂 (30 0mg/ml浓度ultravist) ,流速 5ml/s,总量 4 0ml。在对比剂注射第 9s开始行灌注扫描。扫描条件 :12 0kV ,15 0mA ,速度 1层 /s ,层厚 5～ 8mm ,IOV 2 0 0mm× 2 0 0mm ,连续无间隔扫描 30s,图像重建时间 0 .5s。结果 :在开始注射对比剂第 9s行CT扫描 ,能获得较完整的动脉血管和脑实质内的灌注图像。灌注扫描数据用较小的间隔重建可获得较为平滑的γ 变量曲线。大脑两侧基底节区血流灌注量不等 ,上升值、峰值与上升斜率均左侧大于右侧 ,两者存在显著性差异。结论 :CT灌注技术是研究大脑血流分布的一个新的重要方法。大脑两侧基底节区血流灌注量的差异可能与人们的运动优势习惯有关。     

Simultaneous multi-section perfusion CT and CT angiography for the assessment of acute ischemic stroke

Summary Background. Introduction of helical computed tomography (CT) scanning has enabled rapid imaging of the vascular status by means of CT angiography and perfusion CT. By virtue of recent multi-detector technology, helical CT has the ability to perform both CT angiography and multi-section perfusion CT simultaneously. This study investigated the clinical feasibility of simultaneous assessment of perfusion CT and CT angiography in patients with acute ischemic stroke.Method. Perfusion CT and CT angiography were performed simultaneously in a series of consecutive 31 acute ischemic stroke patients. The time required for the entire processing was about 15 minutes. Contrast agent was used in a total dose of 100ml (35ml for perfusion CT and 65ml for CT angiography).Findings. Simultaneous perfusion CT scans and CT angiographies were of diagnostic quality for 29 patients (94%). In large territorial infarct patients, perfusion CT could predict all perfusion deficits of the final lesions (10 out of 10 lesions) and CT angiography could detect 9 of 10 occlusions of major cerebral arteries (90%). In patients with small lacunar or subcortical infarcts, perfusion CT could predict 9 out of 19 lesions (47.4%), and false-negative were encountered in small lesions (three patients) or in inadequate coverage of data acquisition (seven patients). Acute stage thrombolytic intervention could be carried out based on the findings, and the success of thrombolytic therapy could be demonstrated by follow-up study.Conclusions. Simultaneous perfusion CT and CT angiography is the very useful tool for the rapid and adequate diagnosis of almost all of the large territorial infarcts and some of non-territorial lacunar infarcts. It is an easy-to-perform and safe imaging technique to assess acute ischemic stroke.     

CT-based attenuation correction in 82Rb-myocardial perfusion PET–CT: incidence of misalignment and effect on regional tracer distribution

Purpose Misalignment of low-dose-CT used for attenuation correction (AC) may cause artifacts in cardiac-PET–CT. The aim was to evaluate incidence and severity of misalignment and its quantitative effects on regional myocardial ⁸²Rb-distribution. Methods Rest/dipyridamole ⁸²Rb-perfusion-PET–CT studies of 92 consecutive patients were analyzed for misalignment. Two different scanning protocols were employed: the first 57 patients had separate CTs for rest and stress PET. The following 35 patients had one CT at rest, used for AC of rest and stress PET. Misalignment was visually scored on a five-point scale (0 = no, 1 = minimal, 2 = mild, 3 = moderate, and 4 = severe). In five representative patients with normal perfusion and low probability of disease, 95 polarmaps were created by shifting CT vs PET prior to reconstruction of attenuation-corrected data sets using dedicated software (three dimensions of space; magnitude of shifts, 5, 10, 14 mm). Results PET/CT -misalignment was detected in 60% of rest and 67% of stress studies. Alignment for rest was better than that for stress (0.7 ± 0.7 vs 1.0 ± 0.9, P = 0.03). Comparison of the two protocols revealed no effect on the alignment of the stress study (1.0 ± 0.9 vs 1.0 ± 0.9, P = 0.9). Quantitatively, the largest individual effect of any artificial misalignment was a 25% reduction of relative ⁸²Rb uptake. With a shift of 1 cm, the largest effect in an individual was a 19% decrease. Anterior wall was most frequently influenced by misalignment, but changes of uptake also occurred in all other segments. Conclusions Misalignment between CT and PET in cardiac-PET–CT influences regional tracer distribution in multiple segments. Repeated CT imaging after dipyridamole does not improve alignment. These results emphasize the need for strategies to improve coregistration in clinical imaging protocols.     

Effects of Insulin-like Growth Factor-I and its Analogue,Long-R 3 -IGF-I,on Intestinal Absorption of 3- O -methyl- d -glucose are Less Pronounced than Gut Mucosal Growth Responses

The relationship between insulin-like growth factor-I (IGF-I) peptide-induced increases in bowel mass and functional improvement is unclear. We utilised three independent methods to investigate the effects of IGF-I peptides on intestinal absorption of the glucose analogue, 3- O -methyl- d -glucose (3MG) in rats. Rats received vehicle, IGF-I or the more potent analogue, long-R 3 -IGF-I via subcutaneously implanted mini-pump, for 7 days, at which time intestinal absorption was assessed by: (1) plasma 3MG appearance following oral gavage, (2) single-pass- or (3) recirculating-perfusion of a jejunal segment. 3MG (320 or 800 &#117 mg) was gavaged on day 7 to rats treated with vehicle, IGR-I or long-R 3 -IGF-I. With the lower 3MG dose, only long-R 3 -IGF-I increased (40%) the initial rate of 3MG appearance in plasma. IGF-I had no significant effect, whilst at the higher 3MG dose neither peptide was effective. Utilising perfusion techniques, long-R 3 -IGF-I, but not IGF-I, significantly increased 3MG uptake per cm of jejunum by up to 69%, although significance was lost when expressed as a function of tissue weight. Long-R 3 -IGF-I, but not native IGF-I, enhanced 3MG absorption from the intestinal lumen, presumably reflecting an increased mucosal mass rather than an up-regulation of specific epithelial glucose transporters.     

CT灌注成像在乳腺肿瘤中的临床应用价值

CT灌注成像作为功能成像技术之一,将组织学功能与解剖学结构完美地结合在一起,在血管性病变及肿瘤性病变中有着很高的临床应用价值,在乳腺肿瘤中的应用尚处于起步阶段。此技术可用于乳腺肿瘤的临床诊断、鉴别诊断及治疗监测等几个方面,因而有着广阔的应用前景。本文就CT灌注成像技术的基本原理及其在乳腺肿瘤中的临床应用予以综述。     

多排螺旋CT肝血流灌注参数诊断原发性肝癌的意义探讨

目的探讨多层螺旋CT（MSCT）灌注参数诊断原发性肝癌的临床价值。方法选择本院肝胆外科收治的60例经病理学检查证实的原发性肝癌患者作为研究对象,另选60例健康人作为对照,使用西门子公司生产的Sensation多排螺旋CT成像系统扫描,对肝癌区组织、癌旁组织和正常肝组织扫描结果经软件处理后获取灌注参数。结果肝癌组织血流量（BF）为（214.7.6±34.7） ml/100 g.min^-1、肝动脉灌注量（AP）为（157.4±33.8） ml/（min.ml^-1）、平均通过时间（MTT）为（19.6±5.1）s、肝动脉供血分数（HAF）为（0.69±0.18）×10^-2,显著高于癌旁组织和健康人肝组织（P<0.05）; 肝癌组织对比剂到达时间（IRF To）为（2.14±1.43）s,显著低于癌旁组织或健康人肝组织（P<0.05）;肝癌组织、癌旁组织和健康肝组织毛细血管通透性（PS）的差异无统计学意义（P>0.05）。结论原发性肝癌患者肝癌组织MSCT灌注参数与癌旁组织或健康肝组织存在显著差异,对临床诊断原发性肝癌具有重要意义。     

肝转移癌超声多普勒肝血流灌注指数的测定

目的：评价肝血流灌注指数诊断肝转移癌的临床价值。方法：利用脉冲多普勒超声测定了４组１１０例肝动脉、门静脉血流量，并计算出相应的肝静脉血流与门静脉血流的比值ＤＦＲ和多普勒肝血流灌注指数ＤＰＩ。结果：４个组之间的肝脏总血灌注量相差不明显，Ｐ＞０．０５。肝转移癌组、原发性肝癌组的ＤＰＩ和ＤＦＲ分别为０．３６±０．１１、０．３４±０．１２和０．６０±０．２８、０．５７±０．３７，明显高于对照组、肝内无转移癌组，其ＤＰＩ和ＤＦＲ分别为０．１７±０．０５、０．２０±０．０９和０．２１±０．０８、０．２９±０．１４，Ｐ均＜０．０１。ＤＰＩ、ＤＦＲ诊断肝转移癌的灵敏度８４．６％、特异性８４．９％、正确率８２．４％。结论：本组资料表明，ＤＰＩ或ＤＦＲ不能区别肝转移癌和肝原发癌，但在已知患者有恶性肿瘤的情况下，ＤＰＩ、ＤＦＲ可成为临床早期检出肝转移瘤的十分有价值的指标     

Long-term neurodevelopmental outcome in monochorionic twins after fetal therapy

Monochorionic (MC) twins are at risk for several disorders, including twin-twin transfusion syndrome (TTTS), Twin Reverse Arterial Perfusion (TRAP) and selective intrauterine growth restriction (sIUGR). Several fetal interventions, such as serial amnioreduction (AR), fetoscopic laser coagulation of placental anastomoses (FLC) and selective feticide have lead to improved perinatal morbidity and mortality rates. Nevertheless, the rate of cerebral lesions in MC twins after fetal therapy appears to be high. Follow-up studies show a high incidence of cerebral palsy (CP) and neurodevelopmental impairment (NDI). We performed a systematic review on the long-term neurodevelopmental outcome in MC twins with TTTS following AR and FLC and MC twins following selective feticide of the co-twin due to TTTS, TRAP, sIUGR and congenital anomalies.     

Sustained Axial Loading Lengthens Arteries in Organ Culture

Although it has been recognized for many years that arteries in vivo exist under significant axial strain, studies of the adaptation of arteries to elevated axial strain have only recently been conducted. To determine the effects of sustained elevation of axial loading on arterial structure and function, axial stresses of 250 kPa or greater were applied to porcine common carotid arteries maintained in a perfusion organ culture system for 7 days at physiologic pressure and flow conditions. Our results demonstrated that axial stretch could lead to an increase in unloaded length that was proportional to the axial stretch ratio (stretched length divided by unloaded length) when the axial stretch ratio was above a threshold value of 2.14. Below this threshold, no significant length change occurred. Above this threshold, a significant increase in unloaded length (13 ± %,) and the number of smooth muscle cell nuclei (20 ± 7%) was observed. Permanent length change was associated with a significant decrease in axial stiffness, and the maximum elongation achieved was limited by rupture of the arterial wall. All tested arteries demonstrated good viability and strong vasomotor responses. These results show that arteries in organ culture can elongate under sustained axial loading.