Venography with carbon dioxide as a contrast agent

Purpose The purpose of this study was to evaluate the feasibility, safety, and potential role of carbon dioxide (CO₂) as a contrast agent for venography.Methods Consecutive patients with contraindications to iodinated contrast agents or with unsatisfactory iodinated contrast studies underwent CO₂ digital subtraction venography. The images were rated by three experienced angiographers. Image quality and complications were assessed.Results Over a 14-month period, 66 vein segments were studied in 21 patients. There was good correlation between experienced angiographers on CO₂ image quality (R_i = 0.80) and good agreement on diagnosis (k = 0.62). In 91% of the vein segments evaluated with CO₂ there was interobserver agreement on the diagnosis. Upper extremity veins were adequately imaged with CO₂ alone in all (6/6) patients with contraindications to iodinated contrast. Following suboptimal iodinated contrast studies in six patients, CO₂ produced significantly better quality upper extremity central vein images (p < 0.05). Pain following injection into peripheral veins was the only CO₂-related complication. Inferior vena cava (IVC) filters were successfully deployed with CO₂ alone in 78% (7/9) of patients; two required iodinated contrast.Conclusion Based upon initial experience, CO₂ venography can be recommended in patients with contraindications to iodinated contrast or unsatisfactory iodinated contrast studies.Presented before the Annual Meeting and Postgraduate Course, Cardiovascular and Interventional Radiological Society of Europe, June 7, 1994, Aghia Pelaghia, Crete, Greece.     

胃肠道阴性对比剂在磁共振胰胆管成像中的应用

目的：评价马根维显（Gd—DTPA）溶液作为胃肠道阴性对比剂对改善磁共振胰胆管成像（MRCP）质量的价值。方法：对30例疑有胰、胆管系统疾病的患者口服对比剂前后分别行常规腹部MR和MRCP检查,采用相同的扫描参数及定位。结果：所有病例口服对比剂后MRCP扫描,胃及十二指肠内液体高信号均较前有明显下降,图像质量明显提高。口服稀释的Gd—DTPA溶液前后,MRCP检查胆总管、胰管及胆囊结构的显示效果具有显著性意义（P〈0．05）。结论：口服稀释的Gd—DTPA溶液是一种安全有效降低胃肠道液体高信号强度、改善MRCP图像质量的方法。     

Functional imaging with MR T1 contrast: a feasibility study with blood-pool contrast agent

The aim of this study was to prove the concept of using a long intravenous half-life blood-pool T1 contrast agent as a new functional imaging method. For each of ten healthy subjects, two dynamic magnetic resonance (MR) protocols were carried out: (1) a reference run with a typical T2* echo-planar imaging (EPI) sequence based on the blood oxygenation level-dependent (BOLD) effect and (2) a run with a T1-sensitive three-dimensional (3D) gradient-echo (GRE) sequence using cerebral blood volume (CBV) contrast after intravenous administration of a contrast agent containing a chelate of gadolinium diethylene-triamine-pentaacetate with a phosphono-oxymethyl substituent. All sequences were performed during the execution of a block-type finger-tapping paradigm. SPM5 software was used for statistical analysis. For both runs maximum activations (peak Z-score = 5.5, cluster size 3,449 voxels) were localized in the left postcentral gyrus. Visual inspection of respective signal amplitudes suggests the T1 contrast to be substantially smaller than EPI (0.5% vs 1%). A new functional imaging method with potentially smaller image artefacts due to the nature of CBV contrast and characteristics of the T1 sequence was proposed and verified.     

Perfusion imaging with a freely diffusible hyperpolarized contrast agent

Contrast agents that can diffuse freely into or within tissue have numerous attractive features for perfusion imaging. Here we present preliminary data illustrating the suitability of hyperpolarized ¹³C labeled 2‐methylpropan‐2‐ol (also known as dimethylethanol, tertiary butyl alcohol and tert‐butanol) as a freely diffusible contrast agent for magnetic resonance perfusion imaging. Dynamic ¹³C images acquired in rat brain with a balanced steady‐state free precession sequence following administration of hyperpolarized 2‐methylpropan‐2‐ol show that this agent can be imaged with 2–4s temporal resolution, 2 mm slice thickness, and 700 μm in‐plane resolution while retaining adequate signal‐to‐noise ratio. ¹³C relaxation measurements on 2‐methylpropan‐2‐ol in blood at 9.4T yield T₁ = 46 ± 4s and T₂ = 0.55 ± 0.03s. In the rat brain at 4.7T, analysis of the temporal dynamics of the balanced steady‐state free precession image intensity in tissue and venous blood indicate that 2‐methylpropan‐2‐ol has a T₂ of roughly 2–4s and a T₁ of 43 ± 24s. In addition, the images indicate that 2‐methylpropan‐2‐ol is freely diffusible in brain and hence has a long residence time in tissue; this in turn makes it possible to image the agent continuously for tens of seconds. These characteristics show that 2‐methylpropan‐2‐ol is a promising agent for robust and quantitative perfusion imaging in the brain and body. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

新生儿上消化道造影对比剂的选择

上消化道造影是公认的诊断新生儿上消化道器质性病变较为常用可靠的检查方法[1],既往通常使用硫酸钡作为对比剂,但由于新生儿自身生理及发育因素,使用硫酸钡造影对患儿存在较大的潜在危险因素.本研究旨在通过对比使用水溶性碘对比剂和硫酸钡进行新生儿上消化道造影检查的优劣,探讨新生儿上消化道造影如何正确合理使用对比剂,最大程度避免上消化道造影对患儿造成的不必要危害,并能达到理想的检查效果.     

微泡对比剂与基因治疗

随着超声造影和微泡制备技术的不断发展,微泡对比剂不仅成为诊断工具,而且在基因治疗方面展现出广阔的应用前景.微泡对比剂作为"空化核"起到协同超声辐照的作用,能显著提高超声介导的基因转染,是一种安全的靶向基因转运载体,具有潜在的应用价值.     

Balanced steady-state free precession fMRI with intravascular susceptibility contrast agent

One major challenge in echo planar imaging-based functional MRI (fMRI) is the susceptibility-induced image distortion. In this study, a new cerebral blood volume-weighted fMRI technique using distortion-free balanced steady-state free precession (bSSFP) sequence was proposed and its feasibility was investigated in rat brain at 7 Tesla. After administration of intravascular susceptibility contrast agent (monocrystalline iron oxide nanoparticle [MION] at 15 mg/kg), unilateral visual stimulation was presented using a block-design paradigm. With repetition time/echo time = 3.8/1.9 ms and α = 18°, bSSFP fMRI was performed and compared with the conventional cerebral blood volume-weighted fMRI using post-MION gradient echo and spin echo echo planar imaging. The results showed that post-MION bSSFP fMRI provides comparable sensitivity but with no severe image distortion and signal dropout. Robust negative responses were observed during stimulation and activation patterns were in excellent agreement with known neuroanatomy. Furthermore, the post-MION bSSFP signal was observed to decrease significantly during hypercapnia challenge, indicating its sensitivity to cerebral blood volume changes. These findings demonstrated that post-MION bSSFP fMRI is a promising alternative to conventional cerebral blood volume-weighted fMRI. This technique is particularly suited for fMRI investigation of animal models at high field.     

Intraosseous venography with carbon dioxide contrast agent in percutaneous vertebroplasty

OBJECTIVE: Our objectives were to ascertain whether CO2 can be used as a contrast agent in venography during percutaneous vertebroplasty and to evaluate whether it might be capable of replacing nonionic iodinated contrast agents. CONCLUSION: Intraosseous venography with CO2 contrast agent was slightly inferior to iodine venography in terms of its ability to visualize the vertebral bodies and perivertebral veins, but it remains a useful technique because no interference with optimal visualization of bone cement occurs during the cement injection when CO2 remains within the fracture cleft.     

Cell labeling with the positive MR contrast agent Gadofluorine M

The purpose of this study was to label human monocytes with Gadofluorine M by simple incubation for subsequent cell depiction at 1.5 and 3 T. Gadofluorine M displays a high r(1) relaxivity and is spontaneously phagocytosed by macrophages. Human monocytes were incubated with Gadofluorine M-Cy at varying concentrations and incubation times and underwent MR imaging at 1.5 and 3 T at increasing time intervals after the labeling procedure. R1-relaxation rates and r1 relaxivities of the labeled cells and non-labeled controls were determined. Cellular contrast agent uptake was examined by fluorescence microscopy and quantified by ICP-AES. Efficient cell labeling was achieved after incubation of the cells with 25 mM Gd Gadofluorine M for 12 h, resulting in a maximal uptake of 0.3 fmol Gd/cell without impairment of cell viability. Fluorescence microscopy confirmed internalization of the fluorescent contrast agent by monocytes. The r1 relaxivity of the labeled cells was 137 mM(-1)s(-1) at 1.5 T and 80.46 mM(-1)s(-1) at 3 T. Imaging studies showed stable labeling for at least 7 days. Human monocytes can be effectively labeled for MR imaging with Gadofluorine M. Potential in vivo cell-tracking applications include targeting of inflammatory processes with Gadofluorine-labeled leukocytes or monitoring of stem cell therapies for the treatment of arthritis.     

口服脂肪密度造影剂后胃壁的CT观察

目的：对口服脂肪密度造影剂后，行上腹部CT扫描的正常人胃体部及贲门部胃壁的形态进行观察并通过测量获得胃壁的正常厚度。材料与方法；受检正常人102例，口服脂肪密度造影剂为15％花生油乳剂，经常规上腹部CT扫描后，观察胃体部及贲门部胃壁形态并进行测量，经统计学处理得出平均值。结果：正常人胃体部壁形态光整，厚度在0．2－1．0cm范围之内，中位数0．35cm，贲门部胃壁较胃体部略厚，呈三角形或折角状，厚度在0．2－1．1cm之间，平均值为0．58cm。结论：正常人胃体部及贲门部胃壁光滑，规整、厚度分别应在1．0cm及1．2cm以下。     

自制声学造影剂经静脉声学造影评价肾血流灌注的实验研究

目的:探讨应用自制声学造影剂经静脉声学造影评价肾血流灌注的可行性。方法:应用自制声学造影剂为10只新西兰兔行经静脉肾脏声学造影,观察造影前、后肾脏二维超声图像,描绘肾皮质时间-强度曲线,测定峰值视频强度、基础视频强度、峰值-基础视频强度差及造影剂持续时间等参数。结果:造影后肾脏二维超声图像较造影前明显增强,肾皮质峰值视频强度与造影前(基础)视频强度有显著性差异(P<0.001)。结论:经静脉声学造影可以清楚地的观察到肾脏血流灌注的动态变化,能够对肾脏血流灌注作出定量评价。     

Novel liver macromolecular MR contrast agent with a polypropylenimine diaminobutyl dendrimer core: comparison to the vascular MR contrast agent with the polyamidoamine dendrimer core.

As MRI contrast agents, more hydrophobic molecules reportedly accumulate in the liver and thus are potentially useful as liver MRI contrast agents. In this study, a generation-4 polypropylenimine diaminobutane dendrimer (DAB-Am64), which is expected to be more hydrophobic than the generation-4 polyamidoamine dendrimer (PAMAM-G4D), was used to synthesize a conjugate with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M) [DAB-Am64-(1B4M-Gd)(64)] for complexing Gd(III) ions. This DAB conjugate quickly accumulated in the liver and its characteristics were studied and compared with those of a PAMAM conjugate [PAMAM-G4D-(1B4M-Gd)(64)], which is known to be a useful vascular MRI contrast agent, in regard to its availability as a liver MRI contrast agent. DAB-Am64-(1B4M-Gd)(64) accumulated significantly more in the liver and less in blood than PAMAM-G4D-(1B4M-Gd)(64) (P < 0.001). Contrast-enhanced MRI with DAB-Am64-(1B4M-Gd)(64) was able to homogeneously enhance liver parenchyma and visualize both portal and hepatic veins of 0.5 mm diameter in mice. In conclusion, DAB-Am64-(1B4M-Gd)(64) is a good candidate for a liver MRI contrast agent.     

隔室推药子宫输卵管造影的临床应用

目的探讨隔室手推造影剂子宫输卵管造影的应用价值。方法将12F硅胶球囊导管插入子宫腔，注入2-3mL生理盐水充盈球囊，使球囊堵塞子宫颈内口。延长管与球囊导管和注射器相接，用适当的压力推注造影剂，在电视监视下，确定导管位置良好且嵌塞后，逐渐加压，在子宫腔输卵管逐步充盈时，实时摄片。遇输卵管阻塞时，加压推注，能使轻度粘连阻塞的输卵管再通，发现逆流立即停止推药。结果本组检查2300例，一次造影成功2116例（92％）；二次造影成功115例（5％）；改用子宫颈塞法手推造影69例（3％）。造影示子宫输卵管正常483例（2l％），子宫病变207例（9％），输卵管病变1610例（70％），其中，463例（28．7％）阻塞的输卵管再通。患者无须在放射科插管，医师、患者受照辐射量少，推注压力能灵活调节，未出现严重的并发症。结论该法简便、经济实用、安全、推注压力可调节，图像清晰、隔室推药，辐射剂量小，对轻度粘连阻塞的输卵管有再通作用，值得推广应用。     

Gd-DTPA as a contrast agent in CT

An evaluation was done of the effect of gadolinium diethylenetriaminepentaacetic acid (DTPA) on computed tomographic (CT) studies performed after magnetic resonance (MR) imaging. CT scans of two solutions of Gd-DTPA demonstrated substantial attenuation. In two patients who underwent CT after Gd-DTPA-enhanced MR imaging, the high attenuation of concentrated Gd-DTPA was seen in the urinary bladder and renal collecting system. However, in the concentration presently used in MR imaging, Gd-DTPA results in only minor enhancement of renal cortex.     

A liposomal MRI contrast agent: phosphatidylethanolamine-DTPA

The chelating agent, diethylenetriaminepentaacetic acid (DTPA), was attached via one -COOH group to the amino headgroup of phosphatidylethanolamine to produce a phospholipid which is also a powerful chelating agent. It readily assembles into the walls of lipid bilayer structures as a liposome-associated carrier of cations for MR contrast or radioisotope studies. Freeze-etch electron microscopy showed that phosphatidylethanolamine-DTPA formed satisfactory sonicated vesicles when mixed with natural phospholipids at up to 50 wt%. The resultant structures with bound gadolinium effectively shortened T1 and T2 of surrounding water protons. When sonicated liposomes bearing chelating agent with bound 111In3+ were injected intravenously into rats, uptake was primarily by liver and spleen. By 24 h postinjection there was biliary excretion of this material. Phosphatidylethanolamine-DTPA may have some general utility as an amphiphilic liposomal chelating agent for polyvalent cations.