CT Contrast Agent Research Articles

Dual-source dual-energy CT in the evaluation of hepatic fractional extracellular space in cirrhosis.

One of the main features of liver fibrosis is the expansion of the interstitial space. All water-soluble CT contrast agents remain confined in the vascular and interstitial space constituting the fractional extracellular space (fECS). Indirect measure of its expansion can be quantified during equilibrium phase with CT. The goal of this prospective study was to assess the feasibility of dual-energy CT (DECT) with iodine quantification at equilibrium phase in the evaluation of significant fibrosis or cirrhosis. Thirty-eight cirrhotic patients (according to Child-Pugh and MELD scores), scheduled for liver CT, were enrolled in the study group. Twenty-four patients undergoing CT urography with a 10-min excretory phase were included in the control group. fECS was calculated as the ratio of the iodine concentration of liver parenchyma to that of the aorta, multiplied by 1 minus hematocrit. Final study and control group were, respectively, composed of 22 and 20 patients. Mean hepatic fECS value was statistically greater in study group (P < 0.05). Positive correlation was observed between hepatic fECS value and MELD score (r = 0.64, P < 0.05). Analysis of variance showed statistical differences between control group and the Child-Pugh grades and between Child-Pugh A and B patients and Child-Pugh C patients (P < 0.05). ROC curves analysis yielded an optimum fECS cutoff value of 26.3% for differentiation of control group and cirrhotic patients (AUC 0.88; 86% sensitivity, 85% specificity). Dual-source DECT is a feasible, noninvasive method for the assessment of significant liver fibrosis or cirrhosis.

The radiologist's guide to duplex ultrasound assessment of chronic mesenteric ischemia.

This article reviews the relevant anatomy and physiology of the mesenteric vasculature, familiarizes the radiologist with the accepted diagnostic criteria for mesenteric artery stenosis and its role in the diagnosis of chronic mesenteric ischemia, describes Doppler imaging techniques, and provides protocols for the assessment and surveillance of the mesenteric vasculature before and after revascularization. It also discusses expected changes following revascularization and reviews common post-procedural complications. Duplex sonography plays an important role in the diagnosis and management of chronic mesenteric ischemia (CMI). Establishing a successful diagnosis is dependent upon knowledge of mesenteric arterial anatomy and physiology as well as sufficient expertise in image optimization and scanning techniques. Although there has been a trend toward utilization of other noninvasive [computed tomographic angiography (CTA), magnetic resonance angiography (MRA), and invasive (digital subtraction angiography (DSA)] imaging modalities for assessment of the mesenteric vasculature, a new era of "imaging wisely" raises legitimate concerns about the effects of ionizing radiation as well as potential effects of CT and MR contrast agents. These concerns are obviated by the use of ultrasound, and recently developed techniques, such as contrast-enhanced ultrasound and vascular applications focused on the evaluation of slow flow, have revealed the vast potential of vascular ultrasound in the evaluation of chronic mesenteric ischemia. Duplex sonography is a cost-effective and powerful tool that can be utilized for the accurate assessment of mesenteric vascular pathology, specifically mesenteric arterial stenosis, and for the evaluation of mesenteric arterial system post revascularization.

Comparison of Positive Oral Contrast Agents for Abdominopelvic CT.

OBJECTIVE. The objective of our study was to compare the quality of bowel opacification from three different positive oral contrast agents-barium sulfate, diatrizoate, and iohexol-at abdominopelvic CT. MATERIALS AND METHODS. Abdominopelvic CT examinations with three different oral contrast agents (each contrast agent: n = 300 patients) of 900 patients were retrospectively evaluated by two independent readers. For four segments of the gastrointestinal tract (i.e., the stomach, jejunum, ileum, and colon), readers recorded qualitative data (grade of nonuniform lumen opacification, types of inhomogeneous opacifications, presence of artifacts, and distribution of contrast agent) and quantitative data (CT attenuation of lumen [in Hounsfield units]). The results were compared among the three contrast agents using the Mann-Whitney U test and repeated-measures ANOVA with a post hoc Bonferroni correction. RESULTS. Fewer artifacts were detected with iohexol (4.3%) as the oral contrast agent than with diatrizoate (13.0%) and barium sulfate (14.3%) (each, p < 0.05). Barium showed a greater frequency of bowel lumen heterogeneity (388/831 segments, 47%) than iohexol (155/679, 23%) and diatrizoate (185/763, 24% segments) (p < 0.001). Barium showed higher CT attenuation than iohexol and diatrizoate in the stomach but lower CT attenuation in the ileum (each, p < 0.05). CONCLUSION. The frequency of inhomogeneous bowel opacification was lower for iohexol than for diatrizoate or barium sulfate. Barium showed the highest frequency of bowel lumen heterogeneity. The iodinated agents showed greater increases in mean CT attenuation from the proximal bowel segments to the distal bowel segments than barium sulfate.

Trimodal Nanoparticle Contrast Agent for CT, MRI and SPECT Imaging: Synthesis and Characterization of Radiolabeled Core/Shell Iron Oxide@Gold Nanoparticles

Recently, nanoparticles have emerged as promising contrast agents for various imaging applications. In this paper, we present the synthesis and characterization of a novel hybrid nano-structure, co...

Confined growth of multiple gold nanorices in dual-mesoporous silica nanospheres for improved computed tomography imaging and photothermal therapy.

IntroductionIn this work, we have developed a novel “confined-growth” strategy to synthesize PEGylated multiple gold nanorices-encapsulated dual-mesoporous silica nanospheres (designated as PEGylated MGNRs@DMSSs) containing both small mesopores (2.5 nm) in the shell and large mesopores (21.7 nm) in the core based on a well-established, seed-mediated growth method. The photothermal effect and CT imaging ability were also studied.MethodsThe nanoparticles were characterized by Fourier transform infrared (FT-IR) spectra, N2 absorption isotherms, Field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Confocal microscopy.ResultsThe longitudinally-localized surface (LSPR) absorption properties of MGNRs@DMSSs can be easily tuned by altering the amount of HAuCl4 in the gold growth solution. Additionally, the resultant PEGylated MGNRs@DMSSs have monodispersed, spherical morphology and good colloidal stability in an aqueous solution. More importantly, when exposed to NIR irradiation, the PEGylated MGNRs@DMSSs exhibit both higher temperature increments and better photothermal effects than that of single PEGylated gold nanorods at nearly an equivalent LSPR absorption. In addition, as CT contrast agents, the PEGylated MGNRs@DMSSs display a better CT imaging performance, in comparison with single PEGylated gold nanorods at the same Au concentration.ConclusionTaken together, results indicate the potential for MGNRs@DMSSs used in CT imaging-guided photothermal therapy. Such a simple “confined-growth” strategy within a porous matrix offers a promising platform to design and prepare novel metal(s) oxide@silica nanocomposites for use in further cancer bio-imaging and therapy.

Robotic versus Freehand Needle Positioning in CT-guided Ablation of Liver Tumors: A Randomized Controlled Trial.

Purpose To compare the accuracy of freehand versus robotic antenna placement in CT-guided microwave ablation (MWA) of liver tumors. Materials and Methods This study was conducted as a prospective single-center nonblinded randomized controlled trial (Netherlands Trial Registry, NTR6023). Eligible study participants had undergone clinically indicated CT-guided MWA of liver tumors and were able to receive a CT contrast agent. Randomization was performed per tumor after identification on contrast material-enhanced CT images. The primary outcome was the number of antenna repositionings, which was compared by using the Mann-Whitney U test. Secondary outcomes were lateral targeting error stratified by in-plane and out-of-plane targets and targeting time. Results Between February 14 and November 12, 2017, 31 participants with a mean age of 63 years (range, 25-88 years) were included: 17 women (mean age, 57 years; range, 25-77 years) and 14 men (mean age, 70 years; range, 52-88 years). The freehand study arm consisted of 19 participants, while the robotic study arm consisted of 18 participants; six participants with multiple tumors were included in both arms. Forty-seven tumors were assessed; five tumors were excluded from the analysis because of technical limitations. In the robotic arm, no antenna repositioning was required. In the freehand arm, a median of one repositioning was required (range, zero to seven repositionings; P < .001). For out-of-plane targets, lateral targeting error was 10.1 mm ± 4.0 and 5.9 mm ± 2.9 (P = .007) for freehand and robotic procedures, respectively, and for in-plane targets, lateral targeting error was 6.2 mm ± 2.7 and 7.7 mm ± 5.9, respectively (P = .51). Mean targeting time was 19 minutes (range, 8-55 minutes) and 36 minutes (range, 3-70 minutes; P = .001) for freehand and robotic procedures, respectively. Conclusion Robotic antenna guidance reduces the need for antenna repositioning in microwave ablation to accurately target liver tumors and increases accuracy for out-of-plane targets. However, targeting time was greater with robotic guidance than with freehand targeting. © RSNA, 2019.

CEUS in the paediatric renal tract

The renal indications for the use of intravenous CEUS in pediatric patients include diagnosis and follow-up of suspected complicated infections (carbuncle, abscess), complicated cysts, cystic masses, trauma, suspected infarction, evaluation of transplants, tumour vascularity and where there is a contraindication to CT or MR imaging contrast agents. Contrast-enhanced voiding urosonography (ceVUS) has also proven to be a safe and reliable imaging technique for detecting VUR and urethral abnormalities in children of both genders. CEVUS is a well-established application of pediatric CEUS to diagnose and to stage the severity vesico-ureteral reflux (VUR). The examination is performed following bladder catheterization. UCA is administered intravesically under real time US imaging. The presence of contrast agents (UCA) within the ureter, renal pelvis and calyces is indicative of VUR, graded in a similar manner to voiding cystourethrography (VCUG). There is currently no literature focusing on intra-cavitary use of CEUS in children but application in nephrostomy is possible.

Evaluation of Contrast-Noise Ratio (CNR) in contrast enhanced CT images using different sizes of gold nanoparticles

Abstract High atomic number of nanomaterial has been widely investigated as an alternative contrast agent in radiological procedure. In this study, the enhancement effect of gold nanoparticles (AuNPS) as contrast agent in computed tomography was explored. The Contrast to Noise Ratio (CNR) of AuNPS from two different sizes was compared against an iodine contrast agent (ICA). It was indicated that the different size and concentrations of AuNPS had an effect in alteration the quality of the image contrast. The study also shown AuNPS could be a potential candidate as a future CT contrast agents.

The microscopic dose enhancement factor measurment of bismuth nanoparticles in external radiation therapy using MRI polymer gel dosimetery

Introduction: Bismuth-based nanoparticles having high atomic number and electron density, besides of being utilized as CT contrast agent, stand as a strongly proposed method for dose enhancement in radiotherapy. Embedded nanoparticle in polymer gel dosimeter poses the first step to assess the dose enhancement capability in nanoparticles. To this end, MAGICA gel dosimeter, which is a modified kind of agarose-added magic gel to obtain more stiffness and stability is appropriate method. This study aims at determining the dose enhancement capability of bismuth nanoparticles in this gel under conventional external radiotherapy. Materials and Methods: In current study, the synthesized bismuth nanoparticles approximately with 20 nanometers in diameter and 0.1mM in concentration were injected into MAGICA gel and exposed to 6 MV X-rays beams from linear accelerator simultaneously with control gel samples irradiated in different five doses from 2-10Gy. Results: MAGICA polymer gel response against radiation was characterized by comparing R2 in samples lacking nanoparticles and with Bi-NPs. MAGICA response was found to be linear over the entire dose range explored from 2Gy up to 10 Gy. Results indicated the average dose enhancement factor around 9.8% ± 0.02 in the presence of Bi-NPs. Conclusion: This study investigated the dose enhancement capability of bismuth nanoparticles in external radiotherapy. As well as, MAGICA polymer gel combined with Bi-NPs was approved as a suitable tool for measuring the enhancement of radiation.

The effect of CT contrast agents on treatment planning and dose calculation in radiation therapy of pelvis cancers

Introduction: Using contrast medium in diagnosis and identifying of an organ from its surrounding tissue is very useful. These contrast mediums alter radiation absorption of studied organs. The aim of this study is to identify the influences of contrast media in treatment planning system of the pelvis. Materials and Methods: Seven patients with pelvis area cancer with two sets of CT image, one with contrast medium and another without it, have been used and influences of contrast medium in treatment planning system for these patients were studied. Results: After using contrast medium 2.63% increase in MU for RL field and 0.79%, 1.05%, 1.42% decrease in MU for AP, PA, RL fields have been obtained in rectum, respectively. For Bladder cancer, 0.34% decrease in MU of AP filed and 1.57%, 0.46%, 0.39% increase in MU for PA, RL and LL fields have been calculated, respectively. For cervix cancer, 1.1% decrease for AP field and 0.68% increase for PA field have been obtained. Conclusion: According to the DVHs and calculated MUs, the results showed that the dose differences between the plans for the CT images with and without contrast medium were less than about 1% and was clinically tolerable.

Photoperiodic Flower Mimicking Metallic Nanoparticles for Image-Guided Medicine Applications.

Nanoradiosensitizers have been developed to enhance localization and precision of therapeutic radiation delivery. A specific volume of comprising surface atoms is known to be the radiosensitizing region. However, the shape-dependent local dose enhancement of nanoparticles is often underestimated and rarely reported. Here, a noble metal nanostructure, inspired by the photoperiodic day-flowers, was synthesized by metal reduction with bile acid molecules. The impact of high surface area of day-flowermimicking metallicnanoparticles (D-NP) on radiosensitizing effect was demonstrated with assays for ROS generation, cellular apoptosis, and clonogenic survival of human liver cancer cells (HepG2) cells. In comparison with lower-surface-area spherical night-flower mimickingmetallicnanoparticles (N-NP), exposure of our D-NP to external beam radiation doses led to a significant increase in reactive oxygen species (ROS) production and radiosensitizing cell cycle synchronization, resulting in an enhanced cancer-cell-killing effect. In clonogenic survival studies, dose-enhancing factor (DEF) of D-NP was 16.5-fold higher than N-NP. Finally, we demonstrated in vivo feasibility of our D-NP as a potent nanoradiosensitizer and CT contrast agent for advanced image-guided radiation therapy.

Clinical value of 70 kV combined with low contrast agent CT scan in the diagnosis of pediatric coronary artery disease

Objective DSA and/or surgery was used as a control to evaluate the image quality, radiation dose and diagnostic efficacy of 70 kV combined with low contrast agent dose and 80 kV dual-source CT scanning of coronary artery. Methods Between Apr, 2012 and Apr, 2017, a total of 150 consecutive pediatrics with suspected or confirmed coronary arterial diseases underwent DSCTCA, and the patients were randomly divided into 3 groups by different scanning protocols. Group A (n=50): 80 kV with 1.5 ml/kg contrast agent; Group B (n=50): 70 kV with 1.5 ml/kg contrast agent;Group C (n=50): 70 kV with 1.0 ml/kg contrast agent. ANOVA was used to compare the differences of subjective coronary arteries image quality between the three groups;The t-test was used to compare the difference in effective radiation dose between the 70 kV group and the 80 kV group; The surgery and/or angiography results were used as gold standard to evaluate the diagnostic efficacy of the three groups. Results All patients underwent DSCTCA successfully and satisfactory diagnostic images were gained. The mean scores of subjective image quality of coronary artery were 3.5±0.7, 3.4±0.6, 3.7±0.8, respectively. There was no significant difference between the3 groups (F=2.042, P=0.133). The diagnostic accuracy of the three groups for coronary artery disease was 100%, as the surgical and/or angiographic results were used as gold standard. The effective radiation doses in 80 kV group (A group) and the 70 kV group (B+C group) were (0.49±0.04) and (0.30±0.03) mSv, respectively, with a statistically significant difference (t=4.037, P=0.001). Conclusions DSCTCA can better display and diagnose pediatric coronary artery lesions with 70 kV tube voltage combined with low contrast agent, and has a high diagnostic accuracy. It is a reliable method for diagnosing pediatric coronary artery disease. Key words: Child; Coronary arterial disease; Tomography, X-ray computed; Radiation dosage

An Intravascular Tantalum Oxide–based CT Contrast Agent: Preclinical Evaluation Emulating Overweight and Obese Patient Size

Purpose To compare the CT imaging performance of a carboxybetaine zwitterionic-coated tantalum oxide (TaCZ) nanoparticle CT contrast agent with that of a conventional iodinated contrast agent in a swine model meant to simulate overweight and obese patients. Materials and Methods Four swine were evaluated inside three different-sized adipose-equivalent encasements emulating abdominal girths of 102, 119, and 137 cm. Imaging was performed with a 64-detector row CT scanner at six scan delays after intravenous injection of 240 mg element (Ta or I) per kilogram of body weight of TaCZ or iopromide. For each time point, contrast enhancement of the aorta and liver were measured by using regions of interest. Two readers independently recorded the clarity of vasculature using a five-point Likert scale. Findings were compared by using paired t tests and Wilcoxon signed-rank tests. Results Mean peak enhancement was higher for TaCZ than for iopromide in the aorta (270 HU [σ = 24.5] vs 199 HU [σ = 10.2], P < .001) and liver (61.3 HU [σ = 11.7] vs 45.2 HU [σ = 8], P < .001). Vascular clarity was higher for TaCZ than for iopromide in 63% (132 of 208), 82% (170 of 208), and 86% (178 of 208) of the individual vessels at the 102-, 119-, and 137-cm girths, respectively (P < .01). Arterial clarity scores were higher for TaCZ than for iopromide in 62% (208 of 336) of vessels. Venous clarity scores were higher for TaCZ than for iopromide in 89% (128 of 144) of the veins in the venous phase and in 100% (144 of 144) of veins in the delayed phase (P < .01). No vessel showed higher clarity score with iopromide than with TaCZ. Conclusion An experimental tantalum nanoparticle-based contrast agent showed greater contrast enhancement compared with iopromide in swine models meant to simulate overweight and obese patients. © RSNA, 2018.

CT imaging of myocardial scar burden with CNA35-conjugated gold nanoparticles

Management of patients suffering from myocardial infarction (MI) is based on the extent of coronary artery disease and myocardial scar burden. We have developed a potentially clinically-useful X-ray molecular imaging contrast agent based on gold nanoparticle (AuNPs) functionalized with collagen-binding adhesion protein 35 (CNA35) with the capabilities of achieving prolonged blood pool enhancement for vascular imaging of the coronary arteries and specific targeting of collagen within myocardial scar. At a concentration of ~ 45 mg Au/ml, AuNPs maintained a stable blood pool enhancement at 142–160 HU within an hour of intravenous administration. At 6 hours, specific signal enhancement was detected in the myocardium scar in rats injected with CNA35-AuNPs, but not with control AuNPs or in control animals. In conclusion, CNA35-AuNPs may be considered as a CT contrast agent for both vascular imaging of coronary artery disease and molecular imaging of myocardial scar in the heart.

Microwave-assisted facile synthesis of mono-dispersed Ba/Ho co-doped nanohydroxyapatite for potential application as binary CT imaging contrast agent

It is appealing to develop a facile way to prepare a binary CT contrast agent with good biocompatibility and CT contrast efficiency for potential clinical applications. In this work, a novel binary CT contrast agent based on the biocompatible nano-hydroxyapatite (nHAp, the main inorganic component of human bone and teeth) was prepared facilely and rapidly through doping two kinds of CT contrast ions (Ba2+ and Ho3+) into the nHAp host via microwave-assisted synthesis. The Ba/Ho co-doped nHAp with pure nHAp phase composition and good mono-dispersion was obtained simply with microwave heating for 30 min. The as prepared CT contrast agent is very promising as a novel binary CT contrast agent for CT imaging.

Robust quantitative contrast-enhanced dual-energy CT for radiotherapy applications.

The purpose of this study was to develop and validate accurate methods for determining iodine content and virtual noncontrast maps of physical parameters, such as electron density, in the context of radiotherapy. A simulation environment is developed to compare three methods allowing extracting iodine content and virtual noncontrast composition: (a) two-material decomposition, (b) three-material decomposition with the conservation of volume constraint, and (c) eigentissue decomposition. The simulation allows comparing the performance of the methods using iodine-based contrast agent contents in tissues from a reference dataset with variable density and elemental composition. The comparison is performed in two ways: (a) with a priori knowledge on the composition of the targeted tissue, and (b) without a priori knowledge on the base tissue. The three methods are tested with patient images scanned with dual-energy CT and iodine-based contrast agent. An experimental calibration adapted to the presence of iodine is performed by imaging tissue equivalent materials and diluted contrast agent solutions with known atomic composition. Results show that in the case of known a priori on the composition of the targeted tissue, the two-material decomposition is robust to variable densities and atomic compositions without biasing the results. In the absence of a priori knowledge on the target tissue composition, the eigentissue decomposition method yields minimal bias and higher robustness to variations. Results from the experimental calibration and the images of two patients show that the extracted quantities are accurate and the bias is negligible for both methods with respect to clinical applications in their respective scope of use. For the patient imaged with a contrast agent, virtual noncontrast electron densities are found in good agreement with values extracted from the scan without contrast agent. This study identifies two accurate methods to quantify iodine-based contrast agents and virtual noncontrast composition images with dual-energy CT. One is the two-material decomposition with a priori knowledge of the constituent components focused on organ-specific applications, such as kidney or lung function assessment. The other method is the eigentissue decomposition and is useful for general radiotherapy applications, such as treatment planning where accurate dose calculations are needed in the absence of contrast agent.

Oral Contrast Agents for Pediatric CT and MR Enterography: It's a Matter of Good Taste.

Oral Contrast Agents for Pediatric CT and MR Enterography: It's a Matter of Good Taste.

Quantitative Dual Contrast CT Technique for Evaluation of Articular Cartilage Properties.

Impact injuriesof cartilage may initiate post-traumatic degeneration, making early detection of injury imperative for timely surgical or pharmaceutical interventions. Cationic (positively-charged) CT contrast agents detect loss of cartilage proteoglycans (PGs) more sensitively than anionic (negatively-charged) or non-ionic (non-charged, i.e., electrically neutral) agents. However, degeneration related loss of PGs and increase in water content have opposite effects on the diffusion of the cationic agent, lowering its sensitivity. In contrast to cationic agents, diffusion of non-ionic agents is governed only by steric hindrance and water contentof cartilage. We hypothesize that sensitivity ofan iodine(I)-based cationic agent may be enhanced by simultaneous use of a non-ionic gadolinium(Gd)-based agent. We introduce a quantitative dual energy CT technique (QDECT) for simultaneous quantification of two contrast agents in cartilage. We employ this technique to improve the sensitivity of cationic CA4+ (q =+4) by normalizing its partition in cartilage with that of non-ionic gadoteridol. The technique was evaluated with measurements of contrast agent mixtures of known composition and human osteochondral samples (n = 57) after immersion (72h) in mixture of CA4+ and gadoteridol. Samples were arthroscopically graded and biomechanically tested prior to QDECT (50/100kV). QDECT determined contrast agent mixture compositions correlated with the true compositions (R2= 0.99, average error = 2.27%). Normalizing CA4+ partition in cartilage with that of gadoteridol improved correlation with equilibrium modulus (from ρ = 0.701 to 0.795). To conclude, QDECT enables simultaneous quantification of I and Gd contrast agents improving diagnosis of cartilage integrity and biomechanical status.

Simultaneous Estimation of Bias and Resolution in PET Images With a Long-Lived "Pocket" Phantom System.

A challenge in multicenter trials that use quantitative positron emission tomography (PET) imaging is the often unknown variability in PET image values, typically measured as standardized uptake values, introduced by intersite differences in global and resolution-dependent biases. We present a method for the simultaneous monitoring of scanner calibration and reconstructed image resolution on a per-scan basis using a PET/computed tomography (CT) “pocket” phantom. We use simulation and phantom studies to optimize the design and construction of the PET/CT pocket phantom (120 × 30 × 30 mm). We then evaluate the performance of the PET/CT pocket phantom and accompanying software used alongside an anthropomorphic phantom when known variations in global bias (±20%, ±40%) and resolution (3-, 6-, and 12-mm postreconstruction filters) are introduced. The resulting prototype PET/CT pocket phantom design uses 3 long-lived sources (15-mm diameter) containing germanium-68 and a CT contrast agent in an epoxy matrix. Activity concentrations varied from 30 to 190 kBq/mL. The pocket phantom software can accurately estimate global bias and can detect changes in resolution in measured phantom images. The pocket phantom is small enough to be scanned with patients and can potentially be used on a per-scan basis for quality assurance for clinical trials and quantitative PET imaging in general. Further studies are being performed to evaluate its performance under variations in clinical conditions that occur in practice.

Application of cNGR functionalized gold nanoparticle probe in CT imaging of breast cancer angiogenesis

Objective To prepare polyethylene glycol/cyclic asparagines-glycine-arginine functionalized gold nanoparticles (GNPs-PEG@cNGR) and evaluate their effectiveness in CT imaging of breast cancer angiogenesis. Methods The GNPs were synthesized by one-step reduction of chloroauric acid by sodium citrate. The thiolated PEG and cysteine-modified cNGR were coupled to the surface of GNPs through Au-S bonds, respectively. The GNPs-PEG@cNGR was characterized by transmission electron microscopy, Zeta potential/hydration particle size analyzer, and Fourier transform infrared spectrometer. The uptake and CT imaging effect of GNPs-PEG@cNGR were assessed by human umbilical vein endothelial cells (HUVEC) and human hepatoma cells (HepG2) positively expressed for aminopeptidase N (APN/CD13). The in vivo CT imaging effects on tumor angiogenesis and biocompatibility in mice of GNPs-PEG@cNGR were studied by BALB/c mouse model of 4T1 breast cancer. Results A specific CT molecular probe, i.e. GNPs-PEG@cNGR, was successfully constructed, which can target angiogenesis. The probe was spherical, with a hydration particle size of (35.7±1.0) nm and a Zeta potential of (-13.54±1.12) mV, and had good stability and biocompatibility. The GNPs-PEG@cNGR has good CT imaging results and can specifically target CD13-positive HUVEC and HepG2 cells. The CT imaging results in 4T1 breast cancer mice indicated that GNPs-PEG@cNGR could be specifically enriched in the tumor tissue after injection. The CT value of tumors in GNPs-PEG@cNGRz group was higher than that of GNPs-PEG group, and the difference was statistically significant (P<0.05). Conclusions GNPs-PEG@cNGR can specifically target CD13 positive cells and can be used as a CT contrast agent for imaging tumor angiogenesis. Key words: Cyclic asparagines-glycine-arginine; Gold nanoparticles; Breast cancer; Tumor angiogenesis; CT imaging