Dynamic magnetic resonance angiography of the arteries of the hand. A comparison between an extracellular and an intravascular contrast agent

Eur Radiol 2009;19(2):495-502.


Editor's choice - summary by Jeff Maki

This is an intriguing study of first-pass hand MRA in 11 volunteers, using a sub-systolic blood pressure cuff compression technique (80 mm Hg) to delay venous enhancement and prolong the venous-free phase of imaging. All volunteers were given both gadofosveset and gadoterate (a conventional relaxivity ECF Gd agent approved in Europe) at standard doses (0.03 and 0.1 mmol/kg respectively), and high resolution dynamic MRA was performed at 0.9 mm isotropic resolution with 24 seconds temporal resolution.

This paper describes a nice technique to use for MRA of the hand, an often confusing and difficult vascular territory to image, demonstrating the simplicity and benefit of sub-systolic arm compression. Furthermore, the results showed markedly improved arterial depiction with gadofosveset as compared to gadoterate, as the CNR was ~25% greater, with much better persistence in arterial signal over time (0-3 minutes). Perhaps more importantly, gadofosveset turned in significantly better arterial visualization scores for all sized vessels from the palmar arch to the digital arteries. At the administered doses, with gadofosveset at 30% the molar dose of gadoterate, and given its ~450% increase in relaxivity, the total “relaxivity dose” for gadofosveset is about 35% greater. While the authors believe this may account for some of the observed increase in CNR and image quality, they also point out that the blood-pool properties of gadofosveset appear to maintain the arterial enhancement over a longer period (due to its ability to remain intravascular in the slow-flow situation of the sub-systolic arm compression), thus allowing arterial concentration to build up over time. By contrast, ECF agents will rapidly redistribute outside of the vessel wall into the ECF, which appears to be happening in this study. Venous contamination was comparable for the two agents.

Thus my impression is that hand MRA with sub-systolic venous compression is a unique situation where gadofosveset’s increased relaxivity, and blood-pool properties of slower diffusion out into the extracellular space, combine to strikingly improve MRA image quality. Interesting further work that will hopefully be forthcoming includes a similar study with a high-relaxivity contrast agent such as MultiHance (to see if this is more of a relaxivity-based phenomena than the claimed blood-pool phenomena), and applying the technique to actual patients. Interestingly, the authors did not feel a high-resolution steady state imaging technique, as has been used in the lower extremities, would be effective given the extremely small size of the digital vessels.

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Keywords: Hand arteries, extracellular, intravascular, contrast agent, blood pool, Jeff Maki, magnetic resonance, angiography, ablavar, gadofosveset, gadoterate
Created 13/09/2011 Last updated 06/06/2012