CEUS in abdominal trauma: multi-center study.

The objective of this study was to evaluate the concordance of US and contrast-enhanced US (CEUS) with CT in the assessment of solid organ injury following blunt trauma. Patients underwent complete US examination, including free fluid search and solid organ analysis. CEUS followed, using low-mechanical index techniques and SonoVue. CT was performed within 1 h. Among 156 enrolled patients, 91 had one or more abnormalities (n = 107) at CT: 26 renal, 38 liver, 43 spleen. Sensitivity, specificity, and accuracy for renal trauma at baseline US were 36%, 98%, and 88%, respectively, after CEUS values increased to 69%, 99%, and 94%. For liver baseline US values were 68%, 97%, and 90%; after CEUS were 84%, 99%, and 96%. For spleen, results were 77%, 96%, and 91% at baseline US and 93%, 99%, and 97% after CEUS. Per patient evaluation gave the following results in terms of sensitivity, specificity and accuracy: 79%, 82%, 80% at baseline US; 94%, 89%, and 92% following CEUS. CEUS is more sensitive than US in the detection of solid organ injury, potentially reducing the need for further imaging. False negatives from CEUS are due to minor injuries, without relevant consequences for patient management and prognosis.

Gadocoletic acid trisodium salt (b22956/1): a new blood pool magnetic resonance contrast agent with application in coronary angiography.

RATIONALE AND OBJECTIVES: Inversion recovery, three-dimensional, gradient-recalled echo magnetic resonance coronary angiography (IR-3D-GRE-MRCA), performed after administration of an intravascular T1-relaxing agent with prolonged permanence in the blood, is one of the most promising approaches to noninvasive magnetic resonance imaging (MRI) of the coronaries. The aim of the present study was the evaluation of the physicochemical properties in solution, pharmacokinetics, elimination from the body, protein binding, and signal enhancement characteristics of gadocoletic acid trisodium salt (B22956/1), a candidate gadolinium-based MRI contrast agent for coronary angiography. METHODS: The pharmacokinetics and elimination from the body of gadocoletate ion, the contrastographically active component of gadocoletic acid trisodium salt, was evaluated after intravenous administration in rats and monkeys, using for assays high-performance liquid chromatography, x-ray fluorescence, and inductively coupled plasma atomic emission spectrometry. The binding of the gadocoletate ion to animal and human serum albumin was studied by means of ultrafiltration. The imaging properties of blood outside coronary arteries after contrast agent administration were evaluated in cynomolgus monkeys (Macaca fascicularis) by measuring aortic signal-to-noise and contrast-to-noise ratios in lower body angiograms. The suitability of gadocoletic acid trisodium salt for achieving contrast-enhanced magnetic resonance coronary angiography (ceMRCA) was tested in Yucatan micropigs with an IR-3D-GRE sequence. All in vivo relaxation rate measurement and images were obtained using a 1.5 T Siemens Symphony scanner. RESULTS: The fractional binding of gadocoletate ion at a concentration of 0.5 mM to serum albumin at the physiological concentration was 95%, 92%, 88%, and 86% for human, monkey, pig, and rat, respectively. In rats and monkeys, gadocoletate ion was excreted unmetabolized through the biliary and urinary routes. It was recovered with feces depending on the injected dose in percentages from 18% to 97%, providing evidence for a saturable biliary pathway. Plasma pharmacokinetics showed the complete elimination of gadocoletate ion within 24 hours after administration. In the monkey, the gadocoletate ion showed the pharmacokinetic behavior of a compound with partial vascular confinement and long plasma half-life, which may be ascribed to elevated binding to serum albumin. These properties manifested themselves in lower body angiograms with excellent image contrast between vessels and muscle. The slowly decaying aortic blood signal-to-noise and contrast-to-noise ratios over a 15-minute period is expected to allow 3-dimensional coronary angiography. The potential of gadocoletic acid trisodium salt for ceMRCA was also demonstrated in Yucatan micropigs. Elevated blood signal intensity and almost total myocardial signal suppression was maintained for almost 1 hour after administration, ie, for much longer than expected to be necessary for coronary angiography. During the whole period high resolution images of the right coronary artery could be obtained. CONCLUSIONS: On the basis of the pharmacokinetic profile and imaging characteristics, gadocoletic acid trisodium salt shows promise as a MR contrast agent for coronary angiography.

Comparison of gradient-echo and steady-state free precession for coronary artery magnetic resonance angiography using a gadolinium-based intravascular contrast agent.

OBJECTIVES: Intravascular contrast agents may offer longer imaging times and better vessel visualization over conventional extravascular agents for magnetic resonance coronary angiography. The purpose of this study was to evaluate the effect of intravascular contrast (B-22956/1) on coronary visualization. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared in inversion-recovery (IR)-prepared FLASH (fast low-angle shot) and IR-trueFISP (true fast imaging with steady-state precession) sequences before and after contrast. MATERIALS AND METHODS: Numeric simulations were performed to compare blood signals in IR-trueFISP and IR-FLASH sequences. Coronary imaging was performed in 15 swine. RESULTS: Postcontrast CNR was improved 23% with breathhold IR-FLASH and 55% with breathhold IR-trueFISP as compared with precontrast trueFISP. With free-breathing, long TR IR-FLASH provided 131% and 55.8% higher SNR and 132% and 58.7% increased CNR compared with IR-FLASH with shorter TR and IR-trueFISP, respectively. CONCLUSION: Intravascular contrast agents improve CNR and vessel visualization in coronary magnetic resonance angiography with IR-FLASH and IR-trueFISP.

Single-session magnetic resonance coronary angiography and myocardial perfusion imaging using the new blood pool compound B-22956 (gadocoletic acid): initial experience in a porcine model of coronary artery disease.

OBJECTIVE: The objective of this study was to evaluate a new blood pool contrast agent, B-22956, for detecting myocardial perfusion abnormality and coronary artery stenosis by magnetic resonance imaging (MRI) in 1 setting. MATERIALS AND METHODS: Coronary artery atherosclerotic stenoses were created in 6 miniswine. Myocardial first-pass perfusion imaging was performed with a bolus injection of 0.015 mmol/kg B-22956 during pharmacologic stress followed by postcontrast coronary artery imaging after another injection of B-22956/1. The total doses for the 6 pigs were 0.1 mmol/kg (n=3) and 0.15 mmol/kg (n=3). Perfusion upslope maps were analyzed and MR coronary artery images were reviewed by 2 readers. RESULTS: For all 6 pigs, the normalized upslopes of the perfusion curves were 0.83+/-0.12, 0.74+/-0.15, and 0.52+/-0.05 (P<0.01 vs. normal) with normal or mild (<50% area stenosis), moderate (<50% and <75%), and severe stenosis (>75%), respectively. Mean signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in right coronary artery images improved 90% and 200%, respectively, with a total dose of 0.1 mmol/kg of B-22956. Excellent agreements (kappa=0.82) were achieved for evaluating the grade of stenosis between MR postcontrast coronary artery images and histopathology by 2 reviewers. CONCLUSION: The MR blood pool contrast agent B-22956 demonstrated the ability for detecting myocardial perfusion abnormalities and coronary artery stenosis in 1 setting.

Performance of a new gadolinium-based intravascular contrast agent in free-breathing inversion-recovery 3D coronary MRA.

In three-dimensional (3D) coronary magnetic resonance angiography (MRA), the in-flow contrast between the coronary blood and the surrounding myocardium is attenuated as compared to thin-slab two-dimensional (2D) techniques. The application of a gadolinium (Gd)-based intravascular contrast agent may provide an additional source of signal and contrast by reducing T(1blood) and supporting the visualization of more distal or branching segments of the coronary arterial tree. In six healthy adults, the left coronary artery (LCA) system was imaged pre- and postcontrast with a 0.075-mmol/kg bodyweight dose of the intravascular contrast agent B-22956. For imaging, an optimized free-breathing, navigator-gated and -corrected 3D inversion recovery (IR) sequence was used. For comparison, state-of-the-art baseline 3D coronary MRA with T(2) preparation for non-exogenous contrast enhancement was acquired. The combination of IR 3D coronary MRA, sophisticated navigator technology, and B-22956 allowed for an extensive visualization of the LCA system. Postcontrast, a significant increase in both the signal-to-noise ratio (SNR; 46%, P < 0.05) and contrast-to-noise ratio (CNR; 160%, P < 0.01) was observed, while vessel sharpness of the left anterior descending (LAD) artery and the left coronary circumflex (LCX) were improved by 20% (P < 0.05) and 18% (P < 0.05), respectively.

Insights into the use of paramagnetic Gd(III) complexes in MR-molecular imaging investigations.

Can gadolinium III [Gd(III)] complexes be considered good candidates for magnetic resonance (MR)-molecular imaging studies? In this review article, we examine the principal issues that are the basis of successful use of Gd-based protocols in molecular imaging applications. High relaxivity is the primary requisite. Therefore, the design of such paramagnetic probes has to be pursued keeping in mind the relationships between structure, dynamics, and the relevant parameters involved in paramagnetic relaxation processes. Moreover, the limited number of target molecules on cellular membranes makes it necessary to define strategies aimed at delivering many Gd-containing moieties to the sites of interest. Examples are reported for the attainment of very high relaxivities for the design of new routes for pursuing the accumulation of small sized Gd(III) complexes at the targeting sites. An efficient cellular uptake of Gd-containing probes is the key step for attaining the visualization of targeted cells by MR imaging, and selected examples are reported. In this context, the problem of the assessment of the minimum amount of Gd(III) complexes necessary for the MR imaging-visualization of cells has been addressed by reporting the authors' observations on the cell-internalization of Gd(III) complexes. A particularly efficient delivery system is represented by Gd-loaded apoferritin, which allows the MR visualization of hepatocytes when the number of Gd-complexes per cell is 4 +/- 1 x 10(7). Finally, the potential of responsive systems is considered by outlining the exploitation of the amplification effect brought about by the action of a specific enzymatic activity on the relaxivity of a suitably functionalized Gd(III) complex.