Philipp Riffel MD, Presenter: Nothing to Disclose

Stefan Haneder MD, Abstract Co-Author: Nothing to Disclose

Ulrike I. Attenberger MD, Abstract Co-Author: Nothing to Disclose

Joachim Brade, Abstract Co-Author: Nothing to Disclose

Stefan Oswald Schoenberg MD, PhD, Abstract Co-Author: Nothing to Disclose

Henrik J. Michaely MD, Abstract Co-Author: Consultant, Bayer AG

Different approaches exist for hybrid MRA of the calf station. So far, the order of the acquisition of the focussed calf MRA and the large field of view MRA has not been scientifically evaluated. Therefore the aim of this study was to evaluate if the quality of the combined large field-of-view MRA (CTM MR angiography) and time-resolved MRA with stochastic interleaved trajectories (TWIST MRA) depends on the order of acquisition of the two contrast-enhanced studies.

In this retrospective study, 40 consecutive patients (mean age 68.1 ± 8.7 years, 29 male/ 11 female) who had undergone a MR angiographic protocol that consisted of CTM-MRA (TR/TE, 2.4/1.0ms; 21° flip angle; isotropic resolution 1.2 mm; gadolinium dose, 0.07 mmol /kg) and TWIST-MRA (TR/TE 2.8/1.1; 20° flip angle; isotropic resolution 1.1mm; temporal resolution 5.5s, gadolinium dose, 0.03 mmol/kg), were included. In the first group (group 1) TWIST-MRA of the calf station was performed 1–2 minutes after CTM-MRA. In the second group CTM-MRA was performed 1–2 minutes after TWIST-MRA of the calf station. The image quality of CTM-MRA and TWIST-MRA were evaluated by 2 two independent radiologists in consensus according to a 4-point Likert-like rating scale assessing overall image quality on a segmental basis. Venous overlay was assessed per examination.

In the CTM-MRA, 1360 segments were included in the assessment of image quality. CTM-MRA was diagnostic in 95% (1289/1360) of segments. There was a significant difference (p < 0.0001) between both groups with regard to the number of segments rated as excellent and moderate. The image quality was rated as excellent in the group 1 in 80% (514/640 segments) and in the group 2 in 67% (432/649) respectively (p < 0.0001). In contrast, the image quality was rated as moderate in the first group in 5% (33/640) and in the second group in 19% (121/649) respectively (p < 0.0001). The venous overlay was disturbing in 10% in group 1 and 20% in group 2 (p=n.s.).

If a combined hybrid MRA approach with large field-of-view and time-resolved MRA is acquired the large field-of-view MRA should be acquired first for optimal image quality.

The best image quality in hybrid peripheral MRA is achieved if the large field of view is acquired before the time-resolved MRA.

Riffel, P, Haneder, S, Attenberger, U, Brade, J, Schoenberg, S, Michaely, H, Combined Large Field-of-View MRA and Time-resolved MRA of the Lower Extremities: Optimization of the Chronological Order of Acquisition.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11005661.html