Enhanced tumor detection in the presence of fatty liver disease: Cell-specific contrast agents

It is assumed that hepatobiliary, cell-specific contrast agents will be adversely affected by the presence of diffuse liver disease. The diagnostic efficacy for tumor detection in the presence of fatty liver disease was experimentally studied at contrast-enhanced magnetic resonance (MR) imaging with manganese-DPDP (N,N′-dipyridoxylethylenediamine-N,N′-diacetate 5,5′-bis[phosphate]) and gadobenate dimeglumine (Gd-BOPTA/dimeg) and compared with conventional and chemical shift imaging. Carcinosarcoma was implanted into the liver of rats, and fatty liver was induced with L-ethionine. Without contrast agents, the tumor-fatty liver contrast-to-noise ratio (C/N) was increased on T1-weighted and decreased on T2-weighted MR images relative to tumor-bearing control rats without fatty liver. Chemical shift imaging (phase-contrast method) increased the tumor—fatty liver C/N from 2.3 ± 1.0 to 6.1 ± 1.7 (P <.001). Mn-DPDP and Gd-BOPTA/dimeg increased the tumor—fatty liver C/N from -5.4 ± 1.6 to -11.0 ± 1.9 and ?9.8 ± 3.4, respectively (P <.001). The hepatobiliary, cell-specific contrast agents were equally effective in both fatty and nonfatty liver and outperformed both chemical shift and conventional MR imaging in detecting liver tumors.     

Gadoteridol dose dependence in MR imaging of a liver abscess model

A necrotic liver abscess model was studied with magnetic resonance (MR) imaging at 1.5 T before and after intravenous administration of gadoteridol at doses of 0.1, 0.25, and 0.5 mmol/kg in 24 rabbits. Enhancement characteristics and lesion delineation were assessed with both breath-hold and non-breath-hold imaging techniques. Lesion delineation, as assessed both by signal intensity measurements and evaluations by two image readers blinded to imaging technique, was greatest on high-dose (0.5 mmol/kg) breath-hold images. Lesion rim enhancement was seen consistently only on postcontrast images obtained at a dose of 0.5 mmol/kg and progressed with time after injection of contrast material.     

Use of superparamagnetic contrast media to suppress signal from flowing spins: Preliminary experience

The authors describe their preliminary experience with the use of superparamagnetic magnetic resonance (MR) imaging contrast media for suppression of signal from flowing blood. The goal of this work was to determine if a superparamagnetic contrast agent could successfully eliminate blood signal during cardiac-gated MR imaging, thereby eliminating or reducing flow artifacts associated with the complex and variable hemodynamics within the heart chambers. Imaging and data analysis were performed in 17 dogs subjected to experimental myocardial infarction as part of a parallel project. Six doses (0.2, 1, 2, 3.5, 4, 5, and 10 mg/kg) of AMI-25, an experimental contrast agent, were used in the study. Spin-echo imaging was performed immediately before and every 5 minutes (for an average of 25 minutes) after bolus injection of the contrast agent. Variations in the image signal-to-noise ratio relative to a baseline (before injection of contrast agent) image were assessed as a function of dose and time. Preliminary results suggest that a considerable reduction in blood flow artifacts and, hence, increases in image signal-tonoise ratio can be achieved at doses greater than or equal to 3.5 mg/kg, for approximately 20 minutes after injection. Doses equal to or less than 2 mg/kg and images obtained more than 20 minutes after injection (regardless of dose) did not reliably show hemodynamic artifact suppression.     

Gd-DTPA-cascade-polymer: Potential blood pool contrast agent for MR imaging

Gadolinium-DTPA (diethylenetriaminepentaacetic acid)-cascade-polymer, a potential new blood pool contrast agent for magnetic resonance (MR) imaging, was compared with a known blood pool agent, Gd-DTPA-polylysine, in an animal model. The relative signal intensities of liver, renal cortex, pancreas, and trunk muscle were assessed in 12 pigs between 4 seconds and 120 minutes after injection of a 20 μmol/kg dose of each contrast agent, by using a FLASH (fast low-angle shot) sequence. Except for muscle, all tissues showed visible enhancement after injection of either contrast agent. After injection of Gd-DTPA-polymer, enhancement patterns in the liver, renal cortex, and pancreas were similar to those seen after injection of Gd-DTPA-polylysine. No statistically significant differences in enhancement between the two contrast agents were found at any time point. The authors conclude that the contrast kinetics of Gd-DTPA-cascade-polymer are similar to those of Gd-DTPA-polylysine and that this agent may also be used as a blood pool contrast agent for MR imaging.     

羟基磷灰石-阿霉素复合物对大鼠肝移植性肿瘤局部切除术后治疗作用的研究

目的探讨大鼠肝移植性肿瘤局部切除术后,局部埋置抗癌复合物羟基磷灰石阿霉素对大鼠存活、肿瘤复发和肝功能的影响。方法制作大鼠Ｗ２５６癌肉瘤肝移植瘤模型。肿瘤局部切除后,各组大鼠分别于肝创缘埋置羟基磷灰石阿霉素（Ａ组）;注射阿霉素水溶液（Ｂ组）和注射生理盐水（Ｃ组）。测定各组大鼠术后１、３、７天的肝功能。观察术后３个月大鼠死亡和肿瘤复发情况。结果Ａ组大鼠术后死亡率（２５％,３／１２）及复发率（３３％,４／１２）均较Ｃ组（８３％,１０／１２和９２％,１１／１２）明显下降（Ｐ＜００１）,而复发率（３３％,４／１２）亦较Ｂ组（７５％,９／１２）降低（Ｐ＜００５）,并且肝功能受损亦较Ｂ组减轻（Ｐ＜００５或Ｐ＜００１）。结论羟基磷灰石阿霉素复合物局部埋置,提高了肝移植瘤大鼠局部切除术后的生存率,降低了肿瘤的复发率,对肝功能损害较轻,有一定的临床意义。     

呼吸功能不全综合实验改革的探索

目的:为了探索如何在一次教学实验中将生理学、病理生理学和药理学三个机能学科的实验有机地结合起来, 形成综合性实验以培养学生的综合思维和实验研究能力。方法:在病理生理学的呼吸功能不全实验的基础上, 增加了呼吸的生理调节和不同类型的呼吸衰竭采用不同的针对性药物治疗, 并且采用启发式教学方法。结果:学生学习兴趣明显提高, 学生不仅学到了更多的研究方法, 而且综合分析和科研创新能力都有明显提高。结论:这种改进明显提高了实验课的教学水平和教学质量。     

实验肿瘤局部照射动物模型的改进

目的对局部照射肿瘤实验动物模型进行改进以提高肿瘤放疗增敏药物增敏实验结果的可靠性。方法分别在小鼠腿上皮下（传统方法）和小鼠脚背皮下（改进方法）接种肝癌H22细胞,使其生长成实体瘤;用5Gyγ射线照射肿瘤后,每隔1d测量肿瘤的长、宽、高并计算肿瘤体积,连续观察24d。结果将肿瘤接种于小鼠腿上皮下时,照射组的肿瘤体积和质量与对照组之间的差异无统计学意义（t=0．55、0．70,P均〉0．05）;而将肿瘤接种于脚背皮下时,照射组的肿瘤体积和质量均明显低于对照组（t=2．25,P〈0．05;t=3．14,P〈0．01）。结论肿瘤接种于小鼠脚背皮下的方法,操作简单、方便、易行且实验结果准确、可靠。     

大鼠肝硬变门脉高压性瘀证舌脉诊变化的实验研究

用复制的肝硬变门脉高压性瘀证大鼠模型,以探索舌脉变化与合深静脉压、门脉压、门脉血流量之间的关系.结果实验组大鼠形成坏死后肝硬变,以假小叶Ⅲ期病变为主;舌深静脉压力升高,与门脉压升高呈正相关;门脉血流量明显减少,与对照组比较P<0.01.认为肝硬变门脉高压性瘀证的舌脉粗张与细络瘀血主要是因门脉血经门—腔侧支循环回流入上腔静脉,引起上腔静脉阻力增大,压力增高,导致舌的静脉系统回流受阻,舌深静脉压力升高所致.     

螺旋CT肺动脉造影诊断肺小动脉血栓的实验研究

目的：评价螺旋CT肺动脉造影（spiral CT pulmonary angiography，CTPA）诊断犬肺小动脉血栓栓子（直径2.5-3.5mm）的应用价值。方法：23条实验犬行CTPA空白对照后，制成犬自体血块肺动脉栓塞模型，先后行CTPA与X线肺动脉造影（X-ray pulmonary angiography，XPA）检查，由2名医生在工作站上分析所获图像，并与犬肺病理解剖结果对照，评价CTPA与XPA对肺动脉血栓栓塞的诊断价值。结果：22条犬完成实验全过程，病理解剖发现肺动脉内栓子110个，与人工注入栓子数目相符，均位于肺动脉的段或亚段水平，其中107个位于扫描野内。CTPA发现栓子90个，诊断肺动脉内小血栓栓子的敏感度为84.1％，阳性预测值为93.8％；XPA发现栓子82个，敏感度为76.6％，阳性预测值为94.3％。结论：CTPA对实验性肺小动脉血栓栓子有较高的诊断价值。     

MRI detection of myocardial perfusion defects due to coronary artery stenosis with MS-325

PURPOSE: To assess the value of an intravascular, albumin-targeted contrast agent, MS-325, in visualizing myocardial ischemia with magnetic resonance imaging (MRI). MATERIALS and METHODS: Left anterior descending coronary artery (LAD) stenosis was created in 19 pigs using a closed-chest modified angioplasty technique. Myocardial ischemia was detected by first-pass, contrast-enhanced MRI at peak dipyridamole stress and was compared to Technetium-99m (Tc-99m) sestamibi single photon emission computed tomography (SPECT). Regional coronary blood flow was determined using microspheres. RESULTS: Inducible myocardial ischemia with >40% reduction in stress myocardial blood flow was created in eight animals. An MRI defect, classified as > or=75% reduction in peak myocardial signal intensity in the affected territory, was detected in 92.3% of these animals. In the presence of mild coronary stenosis, there was uniform enhancement with MRI and tracer uptake by SPECT. Concordance of MRI and SPECT for detecting perfusion defects was 85%. CONCLUSION: The pattern of prolonged and persistent MR hypoenhancement of the ischemic myocardial bed using MS-325, which is retained primarily in the vascular bed due to its albumin-binding properties, facilitates the detection of myocardial perfusion defects.