4D flow image quality with blood pool contrast: a comparison of gadofosveset trisodium and ferumoxytol

To evaluate the effect of MRI blood pool contrast agent on 4D flow image quality and ventricular volume measurements. Adult patients referred for clinical cardiac MRI (n?=?22) were imaged with 4D flow. Patients with renal failure (n?=?10) received ferumoxytol, and the remainder (n?=?12) received gadofosveset trisodium. Image quality was assessed with (1) signal-to-noise ratio (SNR); (2) contrast-to-noise ratio (CNR); and (3) 5-point Likert scale based on endocardial border definition (1?=?none; 2?=?partial but unable to visualize; 3?=?able to roughly estimate; 4?=?visible for most of the cardiac cycle; 5?=?excellent definition). A subset (n?=?15) had short axis steady-state free precession (SSFP) cine imaging allowing for comparison of standard volumetric measurement technique with 4D flow derived volumetric measurements. 4D flow studies using ferumoxytol demonstrated a higher median Likert score of 5 (IQR, 5–5) versus 3 (IQR, 2–3). Median cavity SNR and CNR were higher for ferumoxytol compared to gadofosveset trisodium [65 (IQR, 50–74) versus 22 (IQR, 14–28), p?<?0.001; and 40 (IQR, 32–49) versus 4 (IQR, 3–10), p?<?0.001]. Good correlation (p?<?0.001) was seen between SSFP and 4D flow measured ventricular volumes (ESV and EDV) with ferumoxytol (r?=?0.998, mean difference?=?1.2 mL, LOA?=???7.7–10.1 mL) and gadofosveset trisodium (r?=?0.942, mean difference?=???2.7 mL, LOA?=???35.7–27.1 mL). Ferumoxytol used off-label as an MRI blood pool contrast agent offers an attractive alternative to gadofosveset trisodium in patients with renal failure, with excellent 4D flow image quality and good correlation of volumetric measurements compared to the CMR reference (SSFP).     

Comparison between a linear versus a macrocyclic contrast agent for whole body MR angiography in a clinical routine setting

Background

Previous experiences of whole body MR angiography are predominantly available in linear 0.5 M gadolinium-containing contrast agents. The aim of this study was to compare image quality on a four-point scale (range 1–4) and diagnostic accuracy of a 1.0 M macrocyclic contrast agent (gadobutrol, n = 80 patients) with a 0.5 M linear contrast agent (gadopentetate dimeglumine, n = 85 patients) on a 1.5 T whole body MR system. Digital subtraction angiography served as standard of reference.

Results

All examinations yielded diagnostic image quality. There was no significant difference in image quality (3.76 ± 0.3 versus 3.78 ± 0.3, p = n.s.) and diagnostic accuracy observed. Sensitivity and specificity of the detection of hemodynamically relevant stenoses was 93%/95% in the gadopentetate dimeglumine group and 94%/94% in the gadobutrol group, respectively.

Conclusion

The high diagnostic accuracy of gadobutrol in the clinical routine setting is of high interest as medical authorities (e.g. the European Agency for the Evaluation of Medicinal Products) recommend macrocyclic contrast agents especially to be used in patients with renal failure or dialysis.     

In‐vivo high‐resolution X‐ray microtomography for liver and spleen tumor assessment in mice

The present study sought to validate the use of glycery1‐2‐oley‐1,3‐bis‐[7‐(3‐amino‐2,4,6‐triiodophenyl)‐ heptanoate] (DHOG) contrast agent for mouse spleen tumor and liver metastasis imaging by high‐resolution X‐ray microtomography. Three groups of female nude mice were compared: controls (n = 5), and mice injected with 2.5 × 10⁶ STC1 tumor cells in the spleen, imaged at 15 days (group G15, n = 5) and at 30 days (group G30, n = 5, of which one died before imaging). Micro‐CT scans (X‐ray voltage, 50 kVp; anode current, 200 µA; exposure time, 632 ms; 180 rotational steps resulting in 35 µm isotropic spatial resolution) were acquired at 0, 0.75, 2 and 4 h after i.v. injection of DHOG. CT number (Hounsfield units: HU) and contrast‐to‐noise ratios (CNR) were determined in three organs. Statistical analysis was performed by Mann–Whitney U‐test. Contrast enhancement in normal spleen and liver increased, respectively to 1020 ± 159 and 351 ± 27 HU over baseline at 4 h, and 482 ± 3 and 203 ± 14 HU on day 6 after a single contrast injection. Automated three‐dimensional reconstruction and modeling of the spleen provided accurate and quantifiable images. Spleen tumor and liver metastases did not take up DHOG, making them detectable in contrast to the increased signal in normal tissue. The smallest liver metastasis detected measured 0.3 mm in diameter. High‐resolution X‐ray micro‐CT in living mice using DHOG contrast agent allowed visualization and volume quantification of normal spleen and of spleen tumor and its liver metastases. Copyright © 2007 John Wiley & Sons, Ltd.     

Real‐time 3D MRI of contrast agents in whole living mice

A specific mouse whole body coil and a dedicated gradient system at 4.7 T were coupled with an ultra‐fast 3D gradient echo MRI and keyhole reconstruction technique to obtain 3D whole‐body dynamic T₁‐weighted or T₂*‐weighted imaging. The technique was used to visualize the real‐time distribution of non‐targeting T₁ and T₂* contrast agent (CA) in a glioma‐bearing mouse model. T₁ dynamic contrast‐enhancement imaging was performed with a fast imaging with steady‐state precession sequence [echo time/repetition time (TE/TR), 1.32/3.7 ms] before and after CA injection (Gd–DOTA and BSA–Gd–DOTA) for 21 min. The temporal resolution was 1 image/6.5 s. T₂* imaging (TE/TR, 4/8 ms) was performed before and after iron‐based (small and ultra‐small particles of iron oxide) CA injection for 45 min. The temporal resolution was 1 image/14 s. Signal‐to‐noise ratio curves were determined in various mouse organs. The whole‐body coil and gradient systems made it possible to acquire data with sufficient and homogeneous signal‐to‐noise ratio on the whole animal. The spatial resolution allowed adequate depiction of the major organs, blood vessels and brain glioma. The distribution and the time‐course of T₁ and T₂* contrasts upon contrast agent injection were also assessed. 3D whole‐body mouse MRI is feasible at high spatial resolution in movie mode and can be applied successfully to visualize real‐time contrast agent distribution. This method should be effective in future preclinical molecular imaging studies. Copyright © 2011 John Wiley & Sons, Ltd.     

Contrast‐Enhanced Ultrasonography With SonoVue

Objective. We investigated the ability of contrast‐enhanced ultrasonography with SonoVue (Bracco SpA, Milan, Italy), a sulfur hexafluoride microbubble contrast agent, to reveal differences between benign and malignant focal splenic lesions. Methods. In a prospective study we investigated 35 lesions in 35 patients (24 male and 11 female; mean age ± SD, 54 ± 15 years) with focal splenic lesions detected by B‐mode ultrasonography. After intravenous injection of 1.2 to 2.4 mL of SonoVue, the spleen was examined continuously for 3 minutes using low–mechanical index ultrasonography with contrast‐specific software. The final diagnosis was established by histologic examination, computed tomography, or magnetic resonance imaging. Results. In 14 patients, the splenic lesions were malignant (metastasis, n = 6; non‐Hodgkin lymphoma, n = 6; and Hodgkin lymphoma, n = 2). In 21 patients, the focal splenic lesions were benign (ischemic lesion, n = 6; echogenic cyst, n = 5; abscess, n = 4; hemangioma, n = 3; hematoma, n = 1; hemophagocytosis syndrome, n = 1; and splenoma, n = 1. Typical findings for benign lesions were 2 arrival patterns: no contrast enhancement (neither in the early nor in the parenchymal phase; P < .05) and the beginning of contrast enhancement in the early phase followed by contrast enhancement in the parenchymal phase 60 seconds after injection. In contrast, the combination of contrast enhancement in the early phase followed by rapid wash‐out and demarcation of the lesion without contrast enhancement in the parenchymal phase (60 seconds after injection) was typical for malignant lesions (P < .001). Conclusions. Contrast‐enhanced ultrasonography is helpful in the differentiation between benign and malignant lesions of the spleen.     

MR molecular imaging of HER‐2 in a murine tumor xenograft by SPIO labeling of anti‐HER‐2 affibody

In vivo molecular imaging is a rapidly growing research area both for basic and clinical science. Non‐invasive imaging of in vivo conditions at the molecular level increases understanding of the biological characteristics of normal and diseased tissues without the need for invasive surgical procedures. Among the various imaging modalities, magnetic resonance imaging (MRI) has garnered interest as a molecular imaging modality due to its high spatial resolution. Here, we have demonstrated that the combined use of HER‐2 targeting affibody, a small 7 kDa molecule that behaves similarly to antibodies, and superparamagnetic iron oxide (SPIO) can non‐invasively image HER‐2 expressing cells or tissues both in vitro and in vivo by MRI. This preliminary study demonstrates that affibody‐SPIO is a feasible, target‐specific contrast agent for in vivo MR molecular imaging. Copyright © 2010 John Wiley & Sons, Ltd.     

Magnetic resonance molecular imaging of post‐stroke neuroinflammation with a P‐selectin targeted iron oxide nanoparticle

We have developed a magnetic resonance molecular imaging method using a novel iron‐oxide contrast agent targeted towards P‐selectin – MNP‐PBP (magnetic nanoparticle‐P‐selectin binding peptide) – to image endothelial activation following cerebral ischemia/reperfusion. MNP‐PBP consists of ～1000 PBP ligands (primary sequence: GSIQPRPQIHNDGDFEEIPEEYLQ GGSSLVSVLDLEPLDAAWL) conjugated to a 50 nm diameter aminated dextran iron oxide particle. In vitro P‐ and E‐selectin binding was assessed by competition ELISA. Transient focal cerebral ischemia was induced in male C57/BL 6 mice followed by contrast injection (MNP‐PBP; MNP‐NH2; Feridex; MNP‐PBP‐FITC) at 24 h after reperfusion and T₂ magnetic resonance imaging at 9.4 T was performed. Infarction and microvasculature accumulation of contrast agent was assessed in coronal brain sections. MNP‐PBP attenuated antibody binding to P‐selectin by 34.8 ± 1.7%. P‐selectin was preferentially increased in the infarct hemisphere and MNP‐PBP‐FITC accumulation in the infarct hemisphere microvasculature was observed. Compared with the nontargeted iron oxide agents MNP‐NH2 and Feridex, MNP‐PBP showed a significantly greater T₂ effect within the infarction. MR imaging of P‐selectin expression with a targeted iron oxide nanoparticle contrast agent may reveal early endothelial activation in stroke and other neuroinflammatory states. Copyright © 2009 John Wiley & Sons, Ltd.     

Serine‐ and mannose‐modified liposomal contrast agent for computed tomography: evaluation of the enhancement in rabbit liver VX‐2 tumor model

Kupffer cell imaging is a powerful tool for the detection of liver cancer. This diagnostic procedure depends on the faculty of the reticuloendothelial system (RES) which takes up foreign bodies, including small particles. The current study aimed to develop a novel RES targeting liposomal contrast agent that functionalized with serine or mannose, the moiety specifically binding to a corresponding receptor on phagocytic cells. Liposomes loaded with non‐ionic X‐ray contrast media, Iohexol, were prepared by supercritical carbon dioxide reverse‐phase evaporation method and were intravenously injected to healthy rabbits in order to evaluate the liver parenchymal enhancement in X‐ray computed tomography (CT). From 10 to 40 min after injection, the mean enhancement value of the liver parenchyma approached 45 and 34 Hounsfield units (HU) when serine‐modified iodinated liposomal contrast agent (ILCA) and mannose‐modified ILCA were applied, respectively. The tumor‐to‐liver contrast values were also evaluated after the administration of the prepared ILCA to rabbits with VX‐2 carcinoma. For serine‐modified ILCA, tumor‐to‐liver contrast was 82 HU at 1 min and >24 HU at 10–40 min; for mannose‐modified ILCA, the values were 58 HU at 0.5 min and >21 HU at 10–40 min. These vales estimated from the region of intrest and the imaging figures of liver indicate the potential of ILCA for clinical use. Copyright © 2010 John Wiley & Sons, Ltd.     

3.0-T whole-heart coronary magnetic resonance angiography: comparison of gadobenate dimeglumine and gadofosveset trisodium

Gadolinium enhanced coronary magnetic resonance angiography (MRA) at 3 T appears to be superior to non-contrast methods. Gadofosveset is an intravascular contrast agent that may be well suited to this application. The purpose of this study was to perform an intra-individual comparison of gadofosveset and gadobenate for coronary MRA at 3 T. In this prospective randomized study, 22 study subjects [8 (36 %) male; 27.9 ± 6 years; BMI = 22.8 ± 2 kg/m²] underwent two studies using a contrast-enhanced inversion recovery three-dimensional fast low angle shot MRA at 3 T. The order of contrast agent administration was varied randomly, separated by an average of 30 ± 5 days, using either gadobenate dimeglumine (Gd-BOPTA; Bracco, 0.1 mmol/Kg) or gadofosveset trisodium (MS-325; Lantheus Med, 0.03 mmol/Kg). Acquisition time, signal-to-noise ratio (SNR) of coronary vessels and contrast-to-noise ratio (CNR) were evaluated. Of 308 coronary arteries and veins segment analyzed, overall SNR of coronary arteries and veins segments were not different for the two contrast agents (132 ± 79 for gadofosveset vs. 135 ± 78 for gadobenate, p = 0.69). Coronary artery CNR was greater for gadofosveset in comparison to gadobenate (73.5 ± 46.9 vs. 59.3 ± 75.7 respectively, p = 0.03). Gadofosveset-enhanced MRA images displayed better image quality than gadobenate-enhanced MRA images (2.77 ± 0.61 for gadofosveset vs. 2.11 ± 0.51, p < .001). Inter- and intra-reader variability was excellent (ICC > 0.90) for both contrast agents. Gadofosveset trisodium appears to show slightly better performance for coronary MRA at 3 T compared to gadobenate.     

MR imaging assessment of the kinetics of P846, a new gadolinium‐based MR contrast medium,in ischemically injured myocardium

The objectives of the study were: (1) to compare the kinetics of a new gadolinium‐based low‐diffusibility magnetic resonance (MR) contrast medium, P846 and Gd‐DOTA in left ventricular (LV) blood and in normal and ischemically injured myocardium using inversion recovery echo‐planar imaging (IR‐EPI) and (2) to compare the enhancement pattern after injection of P846 with Gd‐DOTA, using T₁‐weighted spin‐echo imaging (T₁‐SE). Sixteen rats were subjected to left descending artery (LAD) occlusion for 30 min, followed by 2.5 h reperfusion. MR imaging was performed before and after administration of the contrast medium in two different groups of animals: one group (n = 8) received 0.05 mmol kg^?1 P846 and the other (n = 8) 0.1 mmol kg^?1 Gd‐DOTA. A blipped IR‐EPI and a multislice T₁‐SE were performed before injection and for 90 min after injection. T₁‐values were derived by fitting regional signal intensity on the IR‐EPI images, the R₁, ΔR₁ (R_{1postcontrast} – R_1precontrast) and ΔR₁ ratios were calculated in LV blood, normal and injured myocardium. On SE‐T₁, the signal intensity ratio (SI) and extent of injury were measured. True infarct size was measured using histochemical staining. Changes in ΔR₁ were 4.8 times greater with 0.05 mmol kg^?1 P846 than with 0.1 mmol kg^?1 Gd‐DOTA in LV blood (6.3 ± 0.9 vs 0.9 ± 0.1 s^?1, p < 0.0001), normal (1.7 ± 0.2 vs 0.34 ± 0.03 s^?1, p < 0.0001) and ischemically injured myocardium (5.4 ± 0.4 vs 1.6 ± 0.1 s^?1, p < 0.0001). MR imaging experiments showed that the signal enhancement with P846 is longer (90 min), which might be explained by a lower diffusion of P846 compared with Gd‐DOTA (30 min). P846 differentiates viable and nonviable myocardium. Despite lower gadolinium dose, P846 permits differentiation of viable and nonviable myocardium owing to a high contrast and a long imaging window with conventional t₁‐weighted SE sequence. Copyright © 2008 John Wiley & Sons, Ltd.     

Morphology,binding behavior and MR‐properties of paramagnetic collagen‐binding liposomes

Collagen is an important component of the extracellular matrix (ECM) and plays an important role in normal tissue maturation and in pathological processes such as atherosclerosis and myocardial infarction. The diagnostics of the latter diseases using MRI could strongly benefit from the use of collagen‐specific contrast agents. The current study aimed to develop a bimodal liposomal MR contrast agent that was functionalized with CNA35, a collagen adhesion protein of the Staphylococcus aureus bacterium. The liposomes were characterized in terms of CNA35 protein conjugation and loading. The overall morphology was assessed with DLS and cryo‐TEM, while cryo‐TEM tomography was used to visualize the protein coverage of the liposomes. The binding properties of the contrast agent were investigated using a fluorescence assay based on the rhodamine content of the liposomes. The bulk relaxivity was determined using regular relaxometry while the MR‐properties of liposomes in their bound state were studied using NMR depth profiling. This CNA35 functionalized contrast agent and the set of in vitro experiments we performed indicate the potential of this technology for in vivo molecular imaging of collagen. Copyright © 2009 John Wiley & Sons, Ltd.     

Mn‐loaded apoferritin: a highly sensitive MRI imaging probe for the detection and characterization of hepatocarcinoma lesions in a transgenic mouse model

Mn‐Apo is a highly sensitive MRI contrast agent consisting of ca. 1000 manganese atoms entrapped in the inner cavity of apoferritin. Part of the metallic payload is in the form of Mn²⁺ ions that endow the nano‐sized system with a very high relaxivity that can be exploited to detect hepatocellular carcinoma in mice. Cellular studies showed that Mn‐Apo is readily taken up by normal hepatocytes via the ferritin transporting route. Conversely, hepatoma cells (HTC) displayed a markedly reduced ability to entrap Mn‐Apo from the culture medium. The i.v. administration of Mn‐Apo into C57BL/6 J mice resulted in a marked liver tissue hyperintensity in T₁‐weighted MR image 20 min after injection. When injected into HBV‐tg transgenic mice that spontaneously develop hepatocellular carcinoma (HCC), Mn‐Apo allowed a clear delineation of healthy liver tissue and tumor lesions as hyperintense and hypointense T₁‐weighted MR images, respectively. Immunohistochemistry analysis correlated Mn‐Apo cellular uptake to SCARA5 receptor expression. When the MRI contrast induced by Mn‐Apo was compared with that induced by Gd–BOPTA (a commercial contrast agent known to enter mouse hepatocytes through organic anion transporters) it was found that only some of the lesions were detected by both agents while others could only be visualized by one of the two. These results suggest that Mn‐Apo may be useful to detect otherwise invisible lesions and that the extent of its uptake directly reports the expression/regulation of SCARA5 receptors. Mn‐Apo contrast‐enhanced MR images may therefore contribute to improving HCC lesion detection and characterization. Copyright © 2012 John Wiley & Sons, Ltd.     

血液循环速度与冠脉CT血管造影增强效果的相关性及对比剂优化方案

  目的  探究血液循环速度与冠状动脉CT血管造影（CTA）增强效果的相关性,并分析对比剂优化方案。  方法  选取2020年1月~2021年4月于我院行冠状动脉CT血管造影患者161例,按照血液循环速度分为快速组（n=32）、中等组（n=35）和缓慢组（n= 94）,分析血液循环速度与增强效果关系,并将缓慢组分为A、B、C 3个亚组,A组与快速组、中等组使用的对比剂浓度和注射速率相同（均为碘浓度320 mgI/mL,速率5 mL/s）;B组采用对比剂的碘浓度为350 mgI/mL,速率5.5 mL/s;C组采用对比剂的碘浓度为370 mgI/mL,速率5.5 mL/s,比较各组伪影发生、室间隔显示、冠脉CT值及图像质量情况。  结果  快速组、中等组、B组、C组产生伪影概率均低于A组,且快速组低于中等组,C组低于B组（P < 0.05）;快速组、中等组、B组、C组主动脉根部CT值、图像质量评分、室间隔显示评分均高于A组,且快速组高于中等组,C组高于B组（P < 0.05）。  结论  血液循环速度能增加冠脉CTA增强效果,清晰显示室间隔,对于血液循环较慢者可适当增加对比剂浓度和注射速率以保证图像质量。      

Hindered diffusion of MRI contrast agents in rat brain extracellular micro‐environment assessed by acquisition of dynamic T1 and T2 maps

The knowledge of brain tissues characteristics (such as extracellular space and tortuosity) represents valuable information for the design of optimal MR probes for specific biomarkers targeting. This work proposes a methodology based on dynamic acquisition of relaxation time maps to quantify in vivo MRI contrast agent concentration after intra‐cerebral injection in rat brain. It was applied to estimate the hindered diffusion in brain tissues of five contrast agents with different hydrodynamic diameters (Dotarem® ≈ 1 nm, P846 ≈ 4 nm, P792 ≈ 7 nm, P904 ≈ 22 nm and Gd‐based emulsion ≈ 170 nm). In vivo apparent diffusion coefficients were compared with those estimated in an obstacle‐free medium to determine brain extracellular space and tortuosity. At a 2 h imaging timescale, all contrast agents except the Gd‐based emulsion exhibited significant diffusion through brain tissues, with characteristic times compatible with MR molecular imaging (<70 min to diffuse between two capillaries). In conclusion, our experiments indicate that MRI contrast agents with sizes up to 22 nm can be used to perform molecular imaging on intra‐cerebral biomarkers. Our quantification methodology allows a precise estimation of apparent diffusion coefficients, which is helpful to calibrate optimal timing between contrast agent injection and MRI observation for molecular imaging studies. Copyright © 2012 John Wiley & Sons, Ltd.     

MR imaging of antigen‐induced arthritis with a new,folate receptor‐targeted contrast agent

The purpose of this study was to investigate if the new folate receptor‐targeted Gd‐chelate P866 may enhance immune‐mediated arthritis. A monoarthritis was induced in the right knee of 15 Sprague–Dawley rats. MR imaging of both knees was performed at 2 T before and up to 2 h and 24 h after injection (p.i.) of P866 (n = 3 dose finding study and n = 6, 0.02 mmol Gd/kg), the non‐FR targeted P866 analog P1001 (n = 3 at 24 h after P866‐administration, 0.02 mmol Gd/kg) or Gd‐DOTA (n = 6, 0.1 mmol Gd/kg). Pulse sequences comprised T₁‐SPGR 80°/50 ms/1.7 ms (flip angle/TR/TE) and inversion recovery 10°/3000 ms/1500 ms/50–3050, 10 000 ms (flip angle/TR/TE/TI) sequences. ΔSI‐data and T₁‐relaxation times of arthritic knees and contralateral normal knees were determined. Folate receptor expression was confirmed with histopathology. All three contrast agents showed an initial perfusion effect with significantly higher ΔSI‐data of arthritic knees compared with normal knees (p < 0.05). In addition, P866, but not P1001 or Gd‐DOTA, showed a prolonged enhancement of the synovitis. Compared with precontrast values, the T₁‐relaxation times of inflamed synovia were significantly decreased at 2 h p.i. of P866 (p < 0.05), but not P1001 or Gd‐DOTA (p > 0.05). Histopathology confirmed the presence of folate receptors in the inflamed joints, but not normal joints. Thus, results suggest a specific accumulation of the folate receptor‐targeted Gd‐chelate P866 in this arthritis model. Copyright © 2007 John Wiley & Sons, Ltd.     

Tumor imaging in small animals with a combined micro‐CT/micro‐DSA system using iodinated conventional and blood pool contrast agents

X‐ray based micro‐computed tomography (CT) and micro‐digital subtraction angiography (DSA) are important non‐invasive imaging modalities for following tumorogenesis in small animals. To exploit these imaging capabilities further, the two modalities were combined into a single system to provide both morphological and functional data from the same tumor in a single imaging session. The system is described and examples are given of imaging implanted fibrosarcoma tumors in rats using two types of contrast media: (a) a new generation of blood pool contrast agent containing iodine with a concentration of 130 mg/mL (Fenestra? VC, Alerion Biomedical, San Diego, CA, USA) for micro‐CT and (b) a conventional iodinated contrast agent (Isovue®‐370 mg/mL iodine, trademark of Bracco Diagnostics, Princeton, NJ, USA) for micro‐DSA. With the blood pool contrast agent, the 3D vascular architecture is revealed in exquisite detail at 100 µm resolution. Micro‐DSA images, in perfect registration with the 3D micro‐CT datasets, provide complementary functional information such as mean transit times and relative blood flow through the tumor. This imaging approach could be used to understand tumor angiogenesis better and be the basis for evaluating anti‐angiogenic therapies. Copyright © 2006 John Wiley & Sons Ltd.     

CT portography by direct intrasplenic contrast injection: a new technique

Background: The evaluation of percutaneous contrast injection into splenic parenchyma as an alternative technique for computed tomographic (CT) portography in the preoperative assessment of primary hepatobiliary tumors. Methods: Thirty-two patients underwent a nonenhanced CT scan of the liver, after which a 19-gauge, 10-cm-long needle was introduced into the splenic parenchyma under CT guidance. One hundred forty milliliters of contrast medium (200 mgI/mL; 28 g/I) were injected through this needle: first, a 20-mL bolus (in 5 s) and then 2 mL/s for 60 s. At the end of the bolus injection (5 s), 8-mm-thick contiguous axial scans of the liver were obtained. Results: The success rate of the procedure was 93.7% (30/32; two technical failures). The average time required for the entire study was 13 min and 50 s (range = 7 min 53 s to 25 min 17 s). Hepatic parenchymal enhancement was good in 24/30 (80%), moderate in 3/30 (10%), and unsatisfactory in caudal sections of the liver in 3/30 (10%). Artifactual perfusion defects were seen in 4/30 (13%) due to inadvertant injection of small quantities of air. Intrasplenic subcapsular contrast accumulation occurred in 56.2% (18/32; minimal 15, moderate 3), extrasplenic contrast leakage in 12.5% (4/32), and left shoulder pain in 18.7% (6/32). No major complications were observed. Conclusions: Direct intrasplenic contrast injection for CT portography is a simple, effective, and safe technique with a high success rate and requires significantly less time and lower doses of contrast medium; it also eliminates angiography, indwelling arterial catheters, and patient transfers from angiography to the CT area. Received: 5 November 1997/Accepted after revision: 11 February 1998     

In vivo comparison of tantalum,tungsten, and bismuth enteric contrast agents to complement intravenous iodine for double‐contrast dual‐energy CT of the bowel

To assess the ability of dual‐energy CT (DECT) to separate intravenous contrast of bowel wall from intraluminal contrast, we scanned 16 rabbits on a clinical DECT scanner: n = 3 using only iodinated intravenous contrast, and n = 13 double‐contrast enhanced scans using iodinated intravenous contrast and experimental enteric non‐iodinated contrast agents in the bowel lumen (five bismuth, four tungsten, and four tantalum based). Representative image pairs from conventional CT images and DECT iodine density maps of small bowel (116 pairs from 232 images) were viewed by four abdominal imaging attending radiologists to independently score each comparison pair on a visual analog scale (?100 to +100%) for (1) preference in small bowel wall visualization and (2) preference in completeness of intraluminal enteric contrast subtraction. Median small bowel wall visualization was scored 39 and 42 percentage points (95% CI 30–44% and 36–45%, both p < 0.001) higher for double‐contrast DECT than for conventional CT with enteric tungsten and tantalum contrast, respectively. Median small bowel wall visualization for double‐contrast DECT was scored 29 and 35 percentage points (95% CI 20–35% and 33–39%, both p < 0.001) higher with enteric tungsten and tantalum, respectively, than with bismuth contrast. Median completeness of intraluminal enteric contrast subtraction in double‐contrast DECT iodine density maps was scored 28 and 29 percentage points (95% CI 15–31% and 28–33%, both p < 0.001) higher with enteric tungsten and tantalum, respectively, than with bismuth contrast. Results suggest that in vivo double‐contrast DECT with iodinated intravenous and either tantalum‐ or tungsten‐based enteric contrast provides better visualization of small bowel than conventional CT. Copyright © 2016 John Wiley & Sons, Ltd.     

不同循环时间患者64排128层螺旋CT冠脉CTA对比剂优化方案研究

目的:探讨冠状动脉CT 造影血液循环速度与增强效果的关系、对图像质量的影响及解决方案.方法:用小剂量团注法测量主动脉根部对比剂达峰值时间,根据循环时间分为循环较快组(A 组)、中等组(B 组)、缓慢组(C 组).C 组随机分为C1、C2、C3 组,C1 组对比剂碘浓度、注射速率与A 组和B 组相同,均使用300 mgI...     

Evaluating the effectiveness of transferrin receptor‐1 (TfR1) as a magnetic resonance reporter gene

Magnetic resonance (MR) reporter genes have the potential for tracking the biodistribution and fate of cells in vivo, thus allowing the safety, efficacy and mechanisms of action of cell‐based therapies to be comprehensively assessed. In this study, we evaluate the effectiveness of the iron importer transferrin receptor‐1 (TfR1) as an MR reporter gene in the model cell line CHO‐K1. Overexpression of the TfR1 transgene led to a reduction in the levels of endogenous TfR1 mRNA, but to a 60‐fold increase in total TfR1 protein levels. Although the mRNA levels of ferritin heavy chain‐1 (Fth1) did not change, Fth1 protein levels increased 13‐fold. The concentration of intracellular iron increased significantly, even when cells were cultured in medium that was not supplemented with iron and the amount of iron in the extracellular environment was thus at physiological levels. However, we found that, by supplementing the cell culture medium with ferric citrate, a comparable degree of iron uptake and MR contrast could be achieved in control cells that did not express the TfR1 transgene. Sufficient MR contrast to enable the cells to be detected in vivo following their administration into the midbrain of chick embryos was obtained irrespective of the reporter gene. We conclude that TfR1 is not an effective reporter and that, to track the biodistribution of cells with MR imaging in the short term, it is sufficient to simply culture cells in the presence of ferric citrate. Copyright © 2016 The Authors Contrast Media & Molecular Imaging Published by John Wiley & Sons Ltd.