Comprehensive MRA of the lower limbs including high-resolution extended-phase infra-inguinal imaging with gadobenate dimeglumine: Initial experience with inter-individual comparison to the blood-pool contrast agent gadofosveset trisodium

Steady State Magnetic Resonance Angiography of the Thoracic Aorta Using Inversion-recovery Steady-State Free Precession and a High Relaxivity Contrast Agent

PURPOSE

To evaluate image quality and aortic dimension measurement accuracy of high resolution, motion compensated steady-state magnetic resonance angiography (SS-MRA) with a high relaxivity, extracellular fluid gadolinium-based contrast agent compared with standard first-pass contrast enhanced MRA (FP-CEMRA) in patients with thoracic aortic aneurysms.

MATERIALS AND METHODS

Sixty-nine patients (mean age, 51.7 y, 25% female) diagnosed with thoracic aortic aneurysms who underwent MRA on a 1.5 T scanner using FP-CEMRA and SS-MRA techniques were retrospectively identified. Quantitative analysis was performed by measuring the aortic diameters at 6 locations within the thoracic aorta for each technique. Two radiologists independently performed the qualitative analysis by assessing the image quality (1 to 5), presence of artifact (1 to 4), signal-to-noise (1 to 4), contrast-to-noise (1 to 4), and wall conspicuity (1 to 4) in the aorta at 4 different locations: the aortic root, the ascending aorta, the aortic arch, and the descending aorta.

RESULTS

The aortic dimensions obtained by SS-MRA had a good correlation with FP-CEMRA. Means for the aortic diameters between the FP-CEMRA and the SS-MRA at all 6 locations demonstrated minimal mean differences (0.013 to 0.044 mm).Qualitative assessment of aorta at 4 locations by 2 reviewers demonstrated that SS-MRA had on average superior image quality at the aortic root and ascending aorta for both reviewers (P<0.05) and at the descending aorta for one reader (P<0.05). Otherwise, both techniques were comparable at the ascending aorta. SS-MRA demonstrated less artifact at the aortic root and the ascending aorta (P<0.05).

CONCLUSION

Aortic dimension measurements provided by SS-MRA with a high relaxivity, extracellular fluid gadolinium-based contrast agent are comparable to the conventional FP-CEMRA. Furthermore, SS-MRA qualitatively demonstrated comparable to better overall image quality than FP-CEMRA at different aortic locations. Therefore, SS-MRA may provide a comparable alternative, or complementary examination to conventional FP-CEMRA in patients who have difficulty breath holding, or in situations where contrast bolus timing was poor.

Lower-limb magnetic resonance angiography: performance of extracellular contrast agents versus blood pool contrast agent for both dynamic and high spatial resolution imaging in extended phase

AIM

To prospectively compare the performance of extracellular space contrast agents (ECSCAs) versus a blood-pool contrast agent (BPCA) for a comprehensive lower-limb magnetic resonance angiography (MRA) protocol in patients with either claudication or critical ischaemia.

MATERIALS AND METHODS

Thirty patients with claudication underwent lower-limb magnetic resonance angiography (MRA) (dynamic crural, three-station bolus chase, and infra-inguinal high resolution) using a triphasic injection method with both a ECSCA and BPCA to allow intra-individual comparison, and 30 patients with critical ischaemia were scanned with either a ECSCA or BPCA. The dynamic, bolus chase, and high-resolution images were scored for quality on a Likert scale (from 1-5). Signal- and contrast-to-noise ratios were analysed and statistical analysis performed.

RESULTS

Overall, there was no statistically significant difference between the ECSCAs and BPCA for arteriographic dynamic imaging, bolus chase MRA, or the high spatial resolution imaging. Venous image quality was rated higher quality for BPCA scans than for ECSCA images for calf veins (not significantly for thigh veins). Venous imaging signal intensity measures were higher for BPCA imaging.

CONCLUSION

Extended-phase imaging using an ECSCA with this protocol provides arteriographic image quality equal to imaging with a BPCA. Venous depiction is good using ECSCAs with this approach, although better with BPCA.

Equilibrium-phase MR angiography: Comparison of unspecific extracellular and protein-binding gadolinium-based contrast media with respect to image quality

The purpose of this study was to compare contrast and image quality of whole-body equilibrium-phase high-spatial-resolution MR angiography using a non-protein-binding unspecific extracellular gadolinium-based contrast medium with that of two contrast media with different protein-binding properties. 45 patients were examined using either 15 mL of gadobutrol (non-protein-binding, n = 15), 32 mL of gadobenate dimeglumine (weakly protein binding, n = 15) or 11 mL gadofosveset trisodium (protein binding, n = 15) followed by equilibrium-phase high-spatial-resolution MR-angiography of four consecutive anatomic regions. The time elapsed between the contrast injection and the beginning of the equilibrium-phase image acquisition in the respective region was measured and was up to 21 min. Signal intensity was measured in two vessels per region and in muscle tissue. Relative contrast (RC) values were calculated. Vessel contrast, artifacts and image quality were rated by two radiologists in consensus on a five-point scale. Compared with gadobutrol, gadofosveset trisodium revealed significantly higher RC values only when acquired later than 15 min after bolus injection. Otherwise, no significant differences between the three contrast media were found regarding vascular contrast and image quality. Equilibrium-phase high-spatial-resolution MR-angiography using a weakly protein-binding or even non-protein-binding contrast medium is equivalent to using a stronger protein-binding contrast medium when image acquisition is within the first 15 min after contrast injection, and allows depiction of the vasculature with high contrast and image quality. The protein-binding contrast medium was superior for imaging only later than 15 min after contrast medium injection.

Vascular imaging: the evolving role of the multidisciplinary team meeting in peripheral vascular disease

This article reviews the importance of preinterventional cross-sectional imaging in the evaluation of peripheral arterial disease, as well as discussing the pros and cons of each imaging modality. The importance of a multidisciplinary team approach is emphasized.