Thoracic and abdominal MRA with gadofosveset: influence of injection rate on vessel signal and image quality. Eur Radiol. 2009;19:1932-1938. [PMID: 19283385 DOI: 10.1007/s00330-009-1381-y]

Thoracic magnetic resonance venography using Gadofosveset in patients with venous pathology-A comparative study of image quality and inter-rater variability

Background High-quality non-invasive imaging of the deep venous system in the thorax is challenging, but nevertheless required for diagnosis of vascular pathology as well as for patient selection and preoperative planning for endovascular procedures. Purpose To compare the diagnostic quality of Gadofosveset-enhanced thoracic magnetic resonance venography, seven consecutive patients with suspected or known disease affecting the central thoracic veins were compared to seven consecutive magnetic resonance venography using conventional gadolinium-based contrast agents. Materials and methods Diagnostic capability, defined as the ability to assess vessel patency and pathologic conditions, for the major thoracic deep venous segments was assessed by two-independent readers. Both reviewers rated the overall subjective image quality on a four-graded scale, and inter-rater variability was analyzed using unweighted and weighted Cohen's kappa values. Results Diagnostic capability was generally considerably higher in the Gadofosveset group for all examined vessel segments. The overall images quality rating was significantly higher for the Gadofosveset group with a mean rating of 2.9 and 2.7 for the two-independent readers, compared to 1.2 and 1.0 for the control croup. Inter-rater variability showed less variability for the Gadofosveset group with a quadratic-weighted Cohen's Kappa value of 0.58 compared to 0.36 for the control group. Conclusion Our results show that Gadofosveset-enhanced magnetic resonance venography of the central thoracic veins is a reliable technique in clinical routine practice that results in diagnostic images, superior to conventional gadolinium-based contrast medium.

Computed tomography angiography and magnetic resonance angiography imaging of the mesenteric vasculature

Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are highly accurate cross-sectional vascular imaging modalities that have almost completely replaced diagnostic catheter angiography for the evaluation of the mesenteric vasculature. CTA is the technique of choice when evaluating patients with suspected mesenteric ischemia; it permits to differentiate between occlusive and nonocclusive etiologies, to evaluate indirect signs of bowel ischemia, and in some instances, to provide alternative diagnoses. MRA has the advantage of not using ionizing radiation and iodinated contrast agents and can be appropriate in the nonacute setting. Both CTA and MRA are suitable for the assessment of patients with suspected chronic mesenteric ischemia, allowing to evaluate the degree of atherosclerotic steno-occlusive disease and the existence of collateral circulation, as well as other nonatherosclerotic vascular pathologies such as fibromuscular dysplasia and median arcuate ligament syndrome. CTA provides excellent depiction of visceral aneurysms and has an important role to plan therapy for both occlusive and aneurysmal diseases and in the follow-up of patients after open or endovascular mesenteric revascularization procedures. This article provides an introduction to the CTA and MRA imaging protocol to study the mesenteric vasculature, the imaging findings in patients presenting with acute and chronic mesenteric ischemia and visceral aneurysms, and the value of these imaging techniques for therapy planning and follow-up.

Magnetic resonance venography and liver transplant complications

Hepatic vein stenosis is a rare but serious complication following liver transplantation. Multiple modalities can be utilized to image the hepatic vasculature. Magnetic resonance venography (MRV) provides certain advantages over ultrasound, computed tomography angiography and digital subtraction venography. MRV utilizes the same imaging principles of magnetic resonance angiography in order to image the venous system. Blood pool contrast agents, specifically gadofosveset trisodium, allow for steady state imaging up to 1 h following injection, with improved visualisation of vital venous structures by utilising delayed steady state imaging. Additionally, the inherent physics properties of magnetic resonance imaging also provide excellent soft tissue detail and thus help define the extent of complications that often plague the post-liver transplant patient. This case report describes the use of gadofosveset trisodium in a patient with hepatic venous stenosis following liver transplantation. Initial venography failed to outline the stenoses and thus MRV using a blood pool contrast agent was utilised in order to delineate the anatomy and plan a therapeutic endovascular procedure.

Improved quality and diagnostic confidence achieved by use of dose-reduced gadolinium blood-pool agents for time-resolved intracranial MR angiography

BACKGROUND AND PURPOSE

Time-resolved MRA with the use of bolus injection of paramagnetic agents has proved valuable in neurovascular imaging. Standard contrast agents have limited blood-pool residence times, motivating the development of highly protein-bound blood-pool agents with greater relaxivity and longer intravascular residence, affording improved image quality at lesser doses. This study represents the first comparison of blood-pool agents to standard agents in time-resolved cerebral MRA.

MATERIALS AND METHODS

One hundred datasets were acquired at 1.5 T by use of a standardized, time-resolved MRA protocol. Patients received either unit dosing of a standard extracellular agent at 0.1 mmol/kg or a blood-pool agent at 0.03 mmol/kg. Peak arterial and venous enhancement phases were identified and subsequently scored qualitatively by use of a 4-point Likert scale, with attention to 6 vascular segments: 1) intracranial ICA; 2) MCA M1; 3) MCA M2; 4) MCA M3; 5) deep cerebral veins; and 6) dural venous sinuses.

RESULTS

Fifty MR angiographies were acquired with each agent. No significant differences were found between agents in generation of uncontaminated arteriograms. Blood-pool agents, at 67% dose reduction, were of significantly greater quality across most vascular segments, including ICA (P = .019), M2 (P = .003), and M3 (P < .01). Superiority in the M1 segment approached significance (P = .059). Significantly better venographic quality was noted for deep venous structures (P = .016) with the use of blood-pool agents.

CONCLUSIONS

Blood-pool agents provide superior demonstration of most intracranial vessels in time-resolved MRA compared with standard agents, at reduced doses. The greater relaxation enhancement and more favorable dosing profile make blood-pool agents superior to standard agents for use in cerebral time-resolved MRA.

Gadofosveset trisodium: abdominal and peripheral vascular applications

OBJECTIVE

The purpose of this review is to illustrate various applications of gadofosveset trisodium in evaluating abdominal and peripheral vascular disease. The basic properties, technical considerations, and clinical and potential future applications of gadofosveset are described.

CONCLUSION

Gadofosveset trisodium facilitates comprehensive high-resolution arterial and venous MR angiography. Because of its prolonged intravascular residence time, gadofosveset trisodium is particularly useful for evaluating venous, dynamic, and functional vascular disease with a single low-dose contrast injection.

Contrast-enhanced time-resolved 4D MRA of congenital heart and vessel anomalies: image quality and diagnostic value compared with 3D MRA

OBJECTIVES

To evaluate time-resolved interleaved stochastic trajectories (TWIST) contrast-enhanced 4D magnetic resonance angiography (MRA) and compare it with 3D FLASH MRA in patients with congenital heart and vessel anomalies.

METHODS

Twenty-six patients with congenital heart and vessel anomalies underwent contrast-enhanced MRA with both 3D FLASH and 4D TWIST MRA. Images were subjectively evaluated regarding total image quality, artefacts, diagnostic value and added diagnostic value of 4D dynamic imaging. Quantitative comparison included signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and vessel sharpness measurements.

RESULTS

Three-dimensional FLASH MRA was judged to be significantly better in terms of image quality (4.0 ± 0.6 vs 3.4 ± 0.6, P < 0.05) and artefacts (3.8 ± 0.4 vs 3.3 ± 0.5, P < 0.05); no difference in diagnostic value was found (4.2 ± 0.4 vs 4.0 ± 0.4); important additional functional information was found in 21/26 patients. SNR and CNR were higher in the pulmonary trunk in 4D TWIST, but slightly higher in the systemic arteries in 3D FLASH. No difference in vessel sharpness delineation was found.

CONCLUSIONS

Although image quality was inferior compared with 3D FLASH MRA, 4D TWIST MRA yields robust images and added diagnostic value through dynamic acquisition was found. Thus, 4D TWIST MRA is an attractive alternative to 3D FLASH MRA.

KEY POINTS

• New magnetic resonance angiography (MRA) techniques are increasingly introduced for congenital cardiovascular problems. • Time-resolved angiography with interleaved stochastic trajectories (TWIST) is an example. • Four-dimensional TWIST MRA provided inferior image quality compared to 3D FLASH MRA but without significant difference in vessel sharpness. • Four-dimensional TWIST MRA gave added diagnostic value.

Combined renal MRA and perfusion with a single dose of contrast

Both anatomical and functional scans are often performed when diagnosing renovascular diseases, which in many cases require two separate contrast injections. With nephrogenic systemic fibrosis being associated with gadolinium, minimizing contrast injection dosage is desirable. In this study, a technique which performs time-resolved renal magnetic resonance angiography (MRA) and perfusion with a single scan and single dose of contrast has been evaluated in six healthy volunteers. A previously developed three-dimensional MRA technique called Contrast-enhanced Angiography with Multi-Echo and Radial k-space (CAMERA) has been used to acquire images, and perfusion analysis was performed using deconvolution methods. Time-resolved MRA, as well as renal blood flow, renal volume of distribution and mean transit time maps, were acquired.

Dynamic contrast-enhanced magnetic resonance angiography of the thoracic vessels: an intraindividual comparison of different k-space acquisition strategies

OBJECTIVES

The combination of parallel acquisition (generalized autocalibrating partially parallel acquisitions) and time-resolved three-dimensional (3D) view-sharing techniques is a promising tool for dynamic contrast-enhanced 3D-magnetic resonance angiography (MRA). We evaluated the influence of different k-space acquisition strategies on image quality for a recently developed time-resolved echo-shared angiographic technique during a contrast-enhanced 3D-MRA of the thoracic vessels.

MATERIALS AND METHODS

In 20 patients (16 men, 4 women; range, 28-75 years), 2 dynamic MRA protocols with different k-space acquisition strategies were performed on a 1.5-T whole-body scanner (MAGNETOM Avanto, Siemens AG, Erlangen, Germany) during injection of 5 mL (flow-rate, 3 mL/s) gadobutrol. For protocol 1, the central-region which was updated with every cycle included 20% of the entire k-space (protocol 2: 10%), the peripheral-region was undersampled by a factor of 10 (protocol 2: 5%). Image quality and details were compared visually. Signal-to-noise ratio and sharpness of vessel borders were estimated.

RESULTS

Morphologic and functional assessment of the pulmonary arteries and the aorta was significantly improved for protocol 1. The sharpness of vessel borders (3.3 mm vs. 4.1 mm; P = 0.001), image quality, and the visibility of image details were significantly improved for protocol 1 compared with protocol 2.

CONCLUSION

The size of the central region that is updated for every frame seems to be more crucial for image quality of echo-shared angiographic techniques than the sampling density in the periphery of the k-space.

Comparison of gadofosveset trisodium and gadobenate dimeglumine during time-resolved thoracic MR angiography at 3T

RATIONALE AND OBJECTIVES

Gadofosveset trisodium is a blood-pool contrast agent (BPA) that shows a less pronounced r1 relaxivity advantage over gadobenate dimeglumine at 3T than at 1.5T. However, there are few data on image quality during first-pass imaging of the thoracic vasculature with gadofosveset trisodium at 3 T. Therefore, it was the aim of this study to compare first-pass imaging characteristics of gadofosveset trisodium to gadobenate dimeglumine during time-resolved contrast-enhanced three-dimensional magnetic resonance angiography (CE MRA) at 3 T.

MATERIALS AND METHODS

Twenty volunteers underwent time-resolved CE MRA on a 3 T magnetic resonance (MR) system with a standard eight-channel phased-array surface coil, receiving either gadofosveset trisodium (blood pool agent [BPA], n = 10) or gadobenate dimeglumine (standard contrast agent, [SCA], n = 10). Image quality was assessed by two independent readers using a Likert scale ranging from 0 = poor quality to 3 = excellent quality, and relative signal-to-noise and contrast-to-noise ratios were calculated.

RESULTS

Equally good to excellent first-pass image quality was confirmed for time-resolved CE MRA using BPA and SCA (arteries, 2.8 ± 0.2 and 2.6 ± 0.4; veins, 2.5 ± 0.3 and 2.2 ± 0.4; artifacts, 2.4 ± 0.2 and 2.3 ± 0.1). Signal-to-noise and contrast-to-noise ratios showed nonsignificant differences, except for left subclavian artery values. There was an overall nonsignificant superiority in signal-to-noise and contrast-to-noise ratios for standard contrast agent in arterial values and BPA regarding venous values.

CONCLUSIONS

Despite a markedly decreased r1/r2 relaxivity ratio, first-pass imaging characteristics of gadofosveset trisodium and gadobenate dimeglumine are equally well suited for first pass time-resolved CE MRA at 3 T.