The effect of intracarotid nonionic contrast media on the blood-brain barrier in acute hypertension.

PURPOSETo determine whether acute hypertension (HT) is a risk factor for damage to the blood-brain barrier in carotid angiography with nonionic contrast media.METHODSAnesthetized rats received intravenous injections of technetium-99m-pertechnetate and horseradish peroxidase. Two groups of rats received metaraminol to raise their blood pressure to between 165 and 190 mmHg peak systolic and then received intracarotid injections of saline or iopamidol. Two other groups remained normotensive and received intracarotid injections of saline or iopamidol. Animals were perfused with a fixative solution and their brains removed. Activity of extravasated Tc-99m-pertechnetate was determined to assess blood-brain barrier breakdown. Brains were then sectioned, treated histochemically to visualize extravasated horseradish peroxidase, and ranked visually according to horseradish peroxidase staining.RESULTSExtravasation of both tracers was significantly greater in the hypertensive group that received contrast media than in the other three groups.CONCLUSIONSAcute hypertension potentiates the blood-brain barrier-damaging effects of nonionic contrast media during carotid angiography in rats.     

Effect of Guglielmi detachable coil placement on intraaneurysmal pressure: experimental study in canines.

BACKGROUND AND PURPOSE: Treatment of ruptured aneurysms with Guglielmi detachable coils (GDCs) has been shown to prevent repeat bleeding. To assess whether GDC coiling alters aneurysmal pressure, we measured intraaneurysmal pressure in two canine types of carotid artery aneurysms before and after GDC placement. METHODS: A 0.014-inch guidewire with a pressure transducer was inserted into parent arteries and domes of surgically created aneurysms. Intravascular static pressures were recorded before and during saline power injections (10, 20, and 30 mL over 1 and 2 s), before and after GDC placement. Common femoral arterial pressure was monitored. RESULTS: Saline power injections reproducibly and abruptly increased pressure in parent arteries and aneurysms. Mean intraaneurysmal pressure varied (18 +/- 4 [10 mL] to 75 +/- 15 mm Hg [30 mL]), independent of injection duration. Intraaneurysmal baseline pressures were higher after GDC placement (111 +/- 10 versus 93 +/- 15 mm Hg; P =.05). Aneurysmal pressure increases with saline injections were slightly higher after GDC placement, which dampened intraaneurysmal pressure amplitude at baseline (26.5 +/- 5.6 versus 19.6 +/- 7.4 mm Hg; P =.003) and during hypertension (25.3 +/- 5.4 versus 19.8 +/- 7.5 mm Hg, P =.002). The pressure increase slope with saline injection was delayed with GDC placement (0.24 +/- 0.1 versus 0.38 +/- 0.19 s; P <.001). CONCLUSION: Graded saline power injections into parent arteries can rapidly increase intraaneurysmal pressure. GDC treatment did not attenuate mean intraaneurysmal pressures, but both dampened the pressure amplitude and delayed pressure increases during locally induced hypertension.     

Intravascular contrast media and the blood-brain barrier. Testing the new nonionic agent ioxilan

The effects of diatrizoate, iohexol, and ioxilan on the blood-brain barrier (BBB) were investigated in normal and hypertensive rats. Anesthetized Wistar rats received 14C-inulin as an indicator for BBB disruption. Diatrizoate, iohexol, or ioxilan (350 and 175 mgI/mL) or normal saline was then injected into the carotid artery (2 mL in 30 seconds). Twenty minutes later, the cardiovascular system was flushed, the brain removed, and each hemisphere was digested. BBB disruption, expressed as counts/minute/mg protein, was compared for each hemisphere in each group by analysis of variance. BBB damage in the diatrizoate-350 group was significantly greater than that in all other groups. No significant BBB damage resulted from iohexol or ioxilan relative to normal saline.     

Factors contributing to blood–brain barrier disruption following intracarotid injection of nonionic iodinated contrast medium for cerebral angiography: experimental study in rabbits

Purpose

This study was performed to investigate the role of injection methods and conditions under a fixed dose of radiographic contrast medium (CM) in respect to promoting blood–brain barrier (BBB) disruption.

Materials and methods

A total of 44 white rabbits (average body weight 2.7 ± 0.4?kg) were used, and their carotid injection was performed with nonionic CM. The variables assessed for the carotid injections included the following: iodine content (300 or 150?mg?I/ml), liquid temperature (37° or 24°C), and the injection time duration (1 or 30?s). The rabbits were divided into five groups. To evaluate BBB disruption, pre- and post-contrast-enhanced magnetic resonance (MR) studies were performed.

Results

Abnormal enhancement of the brain parenchyma in MRI was noted in only one group, which consisted of high-iodine concentration CM injected at a low temperature over a short injection interval. Statistically significant increased values for the percentage of relative enhancement (RE%) were demonstrated (P < 0.05) in comparison with the saline-injected control group.

Conclusion

This result suggests variables that may need to be carefully considered to prevent BBB injury induced by nonionic CM for cerebral angiography, especially in the setting of a neurointerventional procedure.     

增强MRI评价可逆性血脑屏障开放的可靠性及价值

目的评价增强ＭＲＩ在监测可逆性血脑屏障（ＢＢＢ）开放的可靠性及价值。方法３６只家兔被随机分为３组：Ａ、Ｂ两组分别经颈内动脉灌注２０％甘露醇和生理盐水，Ｃ组经耳缘静脉灌注２０％甘露醇。灌注后，立即用０．５Ｔ超导型ＭＲ机进行兔脑冠状位扫描，随后经耳缘静脉注入ＧｄＤＴＰＡ，迅速行同层间隙扫描（增强后５、１０、１５、２０分钟，之后每隔１０分钟），持续２小时。以该层双侧对称的脑实质为兴趣区，测得不同时间兴趣区信号强度（ＳＩ），求其增强率（％）。各组１０只兔于扫描前经耳缘静脉注入２％Ｅｖｅｎｓ蓝（２ｍｌ／ｋｇ），２小时后处死；另有６只分别于灌注后２．５、３小时注入Ｅｖｅｎｓ蓝，１０分钟后处死，取脑观察有无脑实质蓝染，以此来推测ＢＢＢ开放持续时间。所有脑标本送病理检查，并与对应层的ＭＲＩ进行比较。结果Ａ组１０只皆出现灌注侧脑实质增强及蓝染，Ｂ、Ｃ组无一只出现明显强化及蓝染。ＢＢＢ开放持续时间小于３小时。未发现死亡及脑实质病理改变。结论增强ＭＲＩ是监测ＢＢＢ开放过程、指导临床个体化用药的一种理想方法。     

Cardiovascular responses to the intracarotid injections of ionic contrast media and iohexol in the dog

Hypotension and bradycardia are the most significant cardiovascular responses resulting from intracarotid injections of hypertonic contrast media (CM). We have assessed both local and systemic vascular responses to the selective intracarotid injections of ionic and non-ionic CM in twelve pentobarbital anesthetized dogs. Alterations in blood pressure, heart rate, and femoral, renal and carotid blood flows were monitored following right common carotid artery injections of ionic contrast media (282-288 mg I/ml), isotonic saline, and iohexol (300 mg I/ml). Ionic CM led to early (0 to 10 s) decreases in blood pressure, heart rate and femoral vascular resistance. Isotonic saline induced no significant early changes in these same parameters while iohexol caused a decrease in heart rate. Our observations suggest that the early (0 to 10 s) decreases in femoral vascular resistance, heart rate and pressure that occur with the intracarotid injection of hypertonic CM are mediated via the autonomic nervous system and initiated from a site in the carotid circulation. During the 15 to 40 s period when the CM has reached the systemic circulation, iohexol produced smaller effects on systemic blood pressure and peripheral vascular resistances than did the ionic CM. During this 15 to 40 s period there were decreased vascular resistances in the carotid and renal vascular beds that probably result from local effects of the CM, however, the femoral resistance was actually increased. This later increase in femoral resistance probably represents the results of increased sympathetic nervous system activity working to offset the decrease in renal and carotid resistances and thus maintain pressure at baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors contributing to blood-brain barrier disruption following intracarotid injection of nonionic iodinated contrast medium for cerebral angiography: experimental study in rabbits

Purpose This study was performed to investigate the role of injection methods and conditions under a fixed dose of radiographic contrast medium (CM) in respect to promoting blood–brain barrier (BBB) disruption. Materials and methods A total of 44 white rabbits (average body weight 2.7 ± 0.4 kg) were used, and their carotid injection was performed with nonionic CM. The variables assessed for the carotid injections included the following: iodine content (300 or 150 mg I/ml), liquid temperature (37° or 24°C), and the injection time duration (1 or 30 s). The rabbits were divided into five groups. To evaluate BBB disruption, pre- and post-contrast-enhanced magnetic resonance (MR) studies were performed. Results Abnormal enhancement of the brain parenchyma in MRI was noted in only one group, which consisted of high-iodine concentration CM injected at a low temperature over a short injection interval. Statistically significant increased values for the percentage of relative enhancement (RE%) were demonstrated (P < 0.05) in comparison with the saline-injected control group. Conclusion This result suggests variables that may need to be carefully considered to prevent BBB injury induced by nonionic CM for cerebral angiography, especially in the setting of a neurointerventional procedure.     

Gadolinium contrast media are more nephrotoxic than a low osmolar iodine medium employing doses with equal X-ray attenuation in renal arteriography: an experimental study in pigs

RATIONALE AND OBJECTIVES: To investigate in a unilaterally nephrectomized porcine model whether gadolinium contrast media (Gd-CM) are less nephrotoxic than iodine media (I-CM) in x-ray arteriography of a kidney made temporarily ischemic by arterial balloon occlusion. MATERIALS AND METHODS: In a noncrossover design, 3 mL of each test solution were injected in eight pigs (mean weight 19 kg) at a rate of 20 mL/min into the right renal artery at the start of a 10-minute period of ischemia. In group 1 (40 pigs) we injected 0.5 M gadopentetate, 0.5 M gadodiamide, 0.5 M iohexol (190 mg I/mL), 0.18 M iohexol (70 mg I/mL; with an x-ray attenuation equal to that of 0.5 M Gd-CM at 80 kV), and saline. In group 2 (24 pigs), we tested 0.18 M iohexol with ischemia and saline with and without ischemia. Gd- and iodine contrast media functioned as markers of glomerular filtration rate (GFR). When saline was tested, a low dose of iohexol (3 mL per pig; 300 mg I/mL) was injected as GFR marker intravenously in group 1 and into the renal artery in group 2. The plasma half-life elimination times of the CM 1-3 hours after injection were used to compare the effects of the different test solutions on GFR. Longer half-life means lower GFR. RESULTS: Group 1: median plasma half-life elimination time of the GFR marker was 3 340 minutes after injection of 0.5 M gadopentetate, 256 after 0.5 M gadodiamide, 179 after 0.5 M iohexol, 143 after 0.18 M iohexol, and 133 minutes after saline. All differences except that between 0.18 M iohexol and saline were statistically significant (P < .01). Group 2: median plasma half-life was 174 minutes after 0.18 M iohexol with ischemia, 196 minutes after saline with ischemia, and 195 minutes after saline without ischemia. There were no significant differences between the test solutions in group 2 (P > .05). CONCLUSION: In pigs, 0.5 M Gd-CM were more nephrotoxic than both equal-attenuating (70 mg I/mL) and equimolar (190 mg I/mL) concentrations of the I-CM iohexol. These results do not support the "off-label" use of Gd-CM for renal x-ray arteriography in man instead of commercially available concentrations of iodine contrast media at 140, 150 and 180 mg I/mL or diluted to 70 mg I/mL.     

非气性腹腔内加压对肝损伤大鼠的止血效应

目的 评价非气性腹腔内加压作为肝脏损伤后院前救治手段的有效性和安全性.方法 将Wistar大鼠29只按随机数字表法分配进入IAP0、IAP5、IAP10、IAP15组(每组鼠数分别为8,8,8,5只),建立抗凝大鼠严重肝损伤动物模型后,采用非可扩张性充气式气囊相应地行0,5,10,15 mm Hg(1 mm Hg =0.133 kPa)等不同程度的腹腔内加压.实验过程中,如平均动脉压(MAP)＜ 95 mm Hg时,颈静脉内补充乳酸钠林格液(3.3 ml· min-1·kg-1)直至MAP达到100 mm Hg.持续30 min后,以饱和氯化钾处死动物,记录各组动物死亡率、失血量、补液量、肝脏湿重以及MAP等指标.结果 IAP0、IAP5、IAP10组动物无死亡,IAP15组4/5的大鼠于加压后10～15 min内死亡.IAP0、IAP5、IAP10、IAP15组大鼠腹腔内失血量依次减少[(54.20±11.30) ml/kg、(43.98±9.20) ml/kg、(32.49±7.40) ml/kg、(25.77±14.16) ml/kg,P＜0.01].IAP10组补液量高于IAP0、IAP5、IAP15组补液量[(31.06±3.14)ml、(24.94±6.67) ml、(23.06±7.98)ml、( 16.50±7.27) ml,P＜0.05].IAP5、IAP10、IAP15组中肝脏湿重明显大于IAP0组肝脏湿重[(11.18±1.45)g、( 12.13±0.96)g、(11.41±1.20)g、(10.03±0.58)g,P＜0.05].IAP5、IAP10两组MAP差异无统计学意义[(64.81±19.65) mm Hg、( 65.80±15.36 )mm Hg,P＞0.05)],却明显高于IAP0及IAP15组MAP[ (41.22±10.00) mm Hg、(44.50±28.60) mm Hg,P＜0.05)].结论 非气性腹腔内加压对于严重的大鼠肝脏损伤具有止血作用,但需注意避免腹腔内压力过高所致的副作用.     

高血压伴糖耐量减低患者血压晨峰与靶器官损伤的相关性

目的 探讨高血压伴糖耐量减低患者血压晨峰(morning blood pressure surge,MBPS)与靶器官损伤的相关性.方法 选取210例原发性高血压伴糖耐量减低患者,根据动态血压结果分为MBPS组(n=100)和非MBPS组(n=110),比较两组颈动脉内膜中层厚度(IMT)、颈动脉斑块(CA)、左心室肥...     

Aftereffects of exercise and relaxation on blood pressure.

OBJECTIVE: To study the acute aftereffects of exercise and relaxation, performed alone and in combination, on blood pressure (BP) measured at baseline and during stressful conditions. DESIGN: Clinical trial with comparison of groups and repeated measures in each group. SETTING: Exercise Hemodynamic Laboratory, University of S?o Paulo, Brazil. PARTICIPANTS: Fourteen normotensive (NT) and 16 essential hypertensive (HT) subjects. INTERVENTIONS: Four random experimental sessions: relaxation (RX-20 min); exercise [EX-cycle ergometer, 53 min, 50% peak oxygen uptake (VO2peak)]; exercise plus relaxation (EX+RX); and control (C-73 min rest). Measures were taken before and after interventions at baseline and during Stroop color test. MAIN OUTCOME MEASURES: Auscultatory and plesthysmographic BPs. RESULTS: Systolic and diastolic BPs decreased significantly after all the interventions. The decreases in both BPs were significantly greater after the EX+RX session, and were also greater in the HT (EX+RX session, -10+/-1/-7+/-1 and -15+/-2/-8+/-1 mm Hg for the NT and HT, respectively). During mental stress, systolic BP increased significantly and similarly after all the experimental sessions. Diastolic BP also increased significantly during stress; however, the increase was significantly greater after the RX session. At the end of the mental stress, diastolic BP was significantly lower after the EX (74+/-3 mm Hg) and EX+RX (72+/-3 mm Hg) sessions than after the C (79+/-3 mm Hg) and RX (78+/-3 mm Hg) sessions. CONCLUSIONS: In NT and HT subjects, a single bout of exercise or relaxation has hypotensive effects, further enhanced by their combination, and greater in the HT. Moreover, exercise performed alone or in combination with relaxation decreases systolic and diastolic BPs during mental stress.     

Comparison of technetium Tc 99m hexamethylpropyleneamine oxime single-photon emission tomograph with stump pressure during the balloon occlusion test of the internal carotid artery

BACKGROUND AND PURPOSE: Measuring blood pressure (stump pressure) in the distal internal carotid artery during occlusion of the internal carotid artery is reportedly a reliable safety index with which to predict ischemia following permanent occlusion of the internal carotid artery. We compared the stump pressure during occlusion of the internal carotid artery with single-photon emission CT (SPECT) using technetium Tc 99m hexamethylpropyleneamine oxime (HMPAO). METHODS: Twenty-seven patients underwent the balloon occlusion test. After occlusion of the internal carotid artery was performed by a balloon catheter, technetium Tc 99m HMPAO was injected, and then the balloon remained inflated for 15 minutes. The stump pressure was continuously monitored for those 15 minutes. After the balloon catheter was deflated and removed, SPECT was performed. Sixty-four symmetric pairs of regions of interest were set on both sides of the cerebral hemisphere. The radioactivity count ratio (L/n ratio) of the occluded side to the contralateral normal side was calculated. We defined hypoperfusion as an area with an L/n ratio <0.8. The minimum mean stump pressure (minMSP) during the balloon occlusion test and the pressure ratio of the minMSP to the mean systemic pressure were compared with the hypoperfusion area on SPECT. RESULTS: The number of regions of interest with hypoperfusion was significantly (P < .001) greater in patients with a minMSP <40 mm Hg (mean [+/-SD] = 31.5 +/- 13.7) than in patients with a minMSP > or =40 mm Hg (5.1 +/- 4.0). The number of regions of interest with hypoperfusion was also significantly (P < .001) greater in patients with a pressure ratio <0.5 (26.7 +/- 15.8) than in patients with a pressure ratio > or =0.5 (4.5 +/- 3.5). CONCLUSION: The minMSP during the balloon test occlusion reflects the extent of the hypoperfused area measured by SPECT using technetium Tc 99m HMPAO.     

高血压促囊性动脉瘤增大过程中VEGF的作用及其机制的实验研究

目的 研究VEGF在高血压促囊性动脉瘤增大过程中的作用及其机制。方法 SD大鼠24只,以弹性蛋白酶处理右颈外动脉起始部,在1mm处结扎并剪断,建立囊性动脉瘤模型。动物随机均分为高血压组（A组,结扎双侧肾动脉后支升高血压）和对照组（B组）。测量血压变化、动脉瘤的大小。8周时灌注固定取动脉瘤标本,应用免疫组化法评价动脉瘤壁VEGF的表达特点。结果 8周时A组血压明显升高（P〈0．01）,动脉瘤明显大于B组（P〈0．01）,动脉瘤壁中VEGF表达强度明显高于B组（P〈0．01）。结论 血压是影响动脉瘤增大的重要因素,VEGF表达上升可能在动脉瘤瘤体扩大中起一定作用。     

Blood-brain barrier opening by isotonic saline infusion in normotensive and hypertensive animals.

The blood-brain barrier to intravascular Evans blue-albumin was opened in monkeys and rabbits by infusing isotonic saline for 15 s into the common carotid artery, when the external carotid was clamped temporarily and the lingual was catheterized for measuring pressure. Barrier opening correlated better with infusion pressure than with infusion rate, and occurred at carotid artery pressures above 170 mmHg. Systemic hypertension induced by Aramine increased barrier vulnerability by causing a higher net carotid artery pressure to be attained at a given infusion rate.     

Opioid receptor modulation of postexercise hypotension.

Previous studies of both hypertensive and normotensive individuals have indicated a prolonged reduction in blood pressure for several hours after aerobic exercise. In related studies of spontaneously hypertensive rats, this postexercise hypotension has been prevented with naloxone. The purpose of the present investigation was to examined whether the postexercise hypotension may be reversed by antagonism of opioid sensitive receptors with naloxone in normotensive humans. Eight males 22-34 yr of age, participated in two 60-min cycling trials at 60% of VO2 peak, followed by 29 min of recovery. Beginning at 7-min recovery, naloxone or saline (control) was administered intravenously through an indwelling catheter. Blood pressure and heart rate were monitored every 15 min during exercise and every 2 min during recovery. Heart rate was significantly elevated (P < 0.05) over basal levels for the first 11 min of recovery, but from 13 to 29 min was not different from that measured at rest. In both trials, after 11 min of recovery, systolic and mean arterial blood pressures were significantly (P < 0.05) lower than pre-exercise levels (9 +/- 1 mm Hg and 4 +/- 1 mm Hg, respectively). Injection of naloxone (0.1 mg.kg-1) reversed the hypotensive response. However, the reversal was transient, lasting from minutes 15 to 27. Since naloxone reverses postexercise hypotension, opioid sensitive receptors appear to be involved in the reduction in systolic blood pressure following a single bout of submaximal exercise in normotensive humans.     

血压在囊性动脉瘤增大中的作用及作用机制的实验研究

目的　研究血压在囊性动脉瘤增大中的作用及其病理机制。方法　将 4 8只SD大鼠随机分为A、B、C三组 ,每组 16只。以弹性蛋白酶处理右颈外动脉起始部 ,在距起始部 1mm处结扎并剪断 ,建立囊性动脉瘤模型。A组结扎双侧肾动脉后支、B组结扎单侧肾动脉后支以升高血压 ,C组不结扎肾动脉 ,作为对照组。各组分别在喂养 2周、8周时灌注固定取动脉瘤标本。测量 3组大鼠不同时间点的血压及动脉瘤大小 ,并应用免疫组化方法评价各组动脉瘤壁bFGF的表达情况。结果　各组动脉瘤的大小在 2周时无明显差异 ,8周时A组明显大于B组和C组 (P <0 0 1) ,B组和C组差异不显著。 2周时 ,各组bFGF均呈轻度表达 ,8周时A组bFGF表达强度明显高于B组和C组。结论　血压是影响动脉瘤增大的重要因素 ,动脉瘤壁在高血压及血流剪切力的作用下 ,bFGF表达上升 ,动脉瘤重新塑形 ,这可能是动脉瘤瘤体不断扩大的原因之一。     

Blood-brain barrier injury following intracarotid injection of radiographic contrast media. In vivo quantification using magnetic resonance imaging and Gd-DTPA

Changes in signal intensity of the brain at magnetic resonance (MR) imaging before and after Gd-DTPA were used for in vivo quantification of injury to the blood-brain barrier (BBB). Immediately following intracarotid injection of 2 ml/kg of radiographic contrast medium (CM) 0.4 mmol/kg of Gd-DTPA was injected intravenously. MR imaging was performed with a 400/25 partial saturation pulse sequence. The maximum percentage changes (mean +/- SD) in signal intensity of the brain after CM and Gd-DTPA were 1.6 +/- 1.6% with saline, 3.2 +/- 2.0% with iotrolan, 4.3 +/- 1.7% with iohexol, 6.6 +/- 3.6% with ioxaglate and 8.2 +/- 3.6% with diatrizoate. Not only the osmolality but also the ionicity and chemotoxicity seemed to influence Gd-DTPA leakage. A subtle BBB injury had a stronger tendency to occur in the basal ganglia than in the cerebral cortex. MR enhancement is proposed as a sensitive method for in vivo quantification of the BBB injury caused by intracarotid CM injection.     

Acute blood-brain barrier opening in experimentally induced focal cerebral ischemia is preferentially identified by quantitative magnetization transfer imaging.

Pathologic changes in brain tissue during and after stroke may lead to injury of the blood-brain barrier (BBB) and subsequent hemorrhagic transformation (HT). In a rat model of HT, the apparent diffusion coefficient of water, cerebral blood flow, relaxation times, T(1) and T(2), and magnetization transfer (MT) related parameters (T(1sat), K(for) and the MT ratio) were repetitively measured during 3 h of focal ischemia and 2 h of reperfusion (n = 8). Areas of BBB opening were identified by sequential assay of the transcapillary influx of Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) by MRI and (14)C-alpha-aminoisobutyric acid (AIB) by quantitative autoradiography. Ischemia-injured regions of interest were identified from the MRI data and divided into those with and without BBB opening. Of the several MRI parameters measured, the T(1sat) in the caudate-putamen and preoptic area during ischemia and the first 2 h of reperfusion correlated best with the regional pattern of BBB opening observed thereafter. These data suggest that an ipsilateral/contralateral T(1sat) ratio > 1.6 demarcates leakage of small molecules such as Gd-DTPA and AIB across the BBB. As to clinical relevance, the quantitation of MT parameters in acute stroke may enable the early detection of areas of BBB opening and potential HT.     

大鼠脑皮层结构的高分辨锰离子增强7.0 T MRI研究

目的 研究尾静脉给药锰离子增强MRI(MEMRI)显示大鼠脑皮层结构的作用,并比较有无血脑屏障开放对皮层结构显示的影响.方法 15只SD大鼠,采用随机排列表方法随机分为3组,每组5只.A组,右侧颈内动脉注入30%甘露醇开放血脑屏障后尾静脉注100 mmol/L MnCl_2生理盐水溶液,12 h后行MRI;B组,右侧颈内动脉注入生理盐水后尾静脉注100 mmol/L MnCl_2溶液,12 h后行MRI;C组作为正常对照,不做任何处理直接进行MRI.成像采用7.0 T micro-MR扫描仪.采用Paravision 4.0软件测量各组大脑皮层、小脑皮层、嗅球皮层、海马、垂体等ROI的信噪比,各组间信噪比比较采用单因素方差分析,两侧大脑半球间信噪比比较采用配对t检验.结果 MEMRI能清楚显示大鼠脑灰、白质结构及皮层的条带状结构,能显示感觉运动区的解剖边界;室周结构如海马、齿状回、缰联合、嗅球等结构能清楚显示.Mn~(2+)增强后鼠脑右侧大脑皮层、两侧小脑皮层、海马和垂体信噪比升高,A、B、C组SNR值:大脑皮层右侧分别为35.2±7.0、30.1±2.4、26.6±2.8,F=4.36,P=0.038;左侧小脑皮层27.1±5.2、29.4±3.8、19.4±4.5,F=6.66,P=0.011;右侧小脑皮层27.8±3.8、28.5±4.2、20.4±4.8,F=5.84,P=0.017;左侧海马34.5±4.9、38.1±5.3、24.5±3.6,F=11.38,P=0.002;右侧海马35.3±5.5、37.6±4.7、25.6±3.0,F=9.93,P=0.003;垂体39.5±3.8、52.6±9.1、26.2±4.2,F=22.80,P=0.001.其余部位SNR差异无统计学意义(P>0.05).B组两侧皮层强化比较一致.A组两侧皮层不对称强化,开放血脑屏障侧大脑皮层强化更明显,条带状结构显示较模糊,但是两侧半球各部位强化差别无统计学差异(P>0.05).结论 尾静脉给药MEMRI能特异性显示大鼠脑皮质分层结构及感觉运动皮层区的解剖边界.高浓度甘露醇能有效开放血脑屏障,并对脑皮层结构显示产生影响.开放与不开放血脑屏障锰离子MEMRI各具特征,可以根据实际需要进行选择.     

Tumor oxygenation using direct injection of oxygenated saline

Direct injection of oxygen into an in-vivo tumor system was performed using saline lavage through a double-lumen catheter inserted into a Walker 256 carcinoma implanted in the flank of a rat. Ten extremely hypoxic tumors (core pO2 0 to 1 mm Hg) were examined. The mean pO2 in these tumors increased from 66 to 112 mm Hg after 5 minutes of lavage with oxygenated saline. These results indicate a substantial increase in tumor pO2 can be obtained with this system, possibly resulting in improved radioresponsiveness. More general applications of this system may also be feasible.