Oisin Jude Flanagan MBBCh, MRCPI, Presenter: Nothing to Disclose

Shivraman Giri PhD, Abstract Co-Author: Employee, Siemens AG

Ioannis Koktzoglou PhD, Abstract Co-Author: Research support, Siemens AG

David Grodzki, Abstract Co-Author: Employee, Siemens AG

Navyash Gupta, Abstract Co-Author: Nothing to Disclose

Robert R. Edelman MD, Abstract Co-Author: Research support, Siemens AG Royalties, Siemens AG

To develop a method of visualizing peripheral arterial calcification without using ionizing radiation so that patients with PAC and renal failure may receive adequate evaluation of their peripheral vessels to guide management.

Following institutional IRB approval, 8 patients (6 male, age 57-78 years, with known peripheral arterial disease on CT angiogram were recruited for a research MRA on a 1.5T system (Avanto, Siemens Technology, Erlangen, Germany). Each underwent (1) gradient echo pulse sequence using flow compensation with in-phase echo time (TE) and (2) 3D pointwise encoding time reduction with radial acquisition (PETRA) with ultra-short TE. Voxel size was 0.52 to 1mm3 Images were assessed for image quality (1-5) and the presence of calcium. Individual calcium plaques were quantitatively assessed for calcium: lumen, calcium: fat and calcium: muscle CNR and SNR.

Both the gradient echo and PETRA sequences each showed all the calcific foci present on CT. The two MRI sequences showed image quality of 4.8 (SD 0.2) and 4.0 (SD 0.0) respectively (p=0.038) and calcium: lumen contrast to noise ratio (CNR) of 46.9 (SD 20.0) and 29.5 (SD 11.6), respectively. (p=0.045).

Both Gradient echo pulse sequence using flow compensation with in-phase TE and PETRA are sensitive for the detection of peripheral vascular calcification. The significant calcium: lumen contrast to noise ratio, combined with high spatial resolution can allow radiologists and clinicians to determine the lumen and calcific plaque morphology.

This has significant clinical relevance as many renal patients also have peripheral vascular disease but cannot have  contrast enhanced CTA due to contrast induced nephropathy risk. Non-enhanced CT will provide adequate evaluation of the calcium but without luminal evaluation the significance of plaques is limited. Non-enhanced Peripheral MRI, either on its own or combined with nonenhanced peripheral MRA will allow nonenhanced evaluation of both lumen and calcification and provide a growing cohort of vascular patients with satisfactory vascular assessment to guide optimal  intervention.

Flanagan, O, Giri, S, Koktzoglou, I, Grodzki, D, Gupta, N, Edelman, R, "Novel MR for Peripheral Calcium Score" ; Evaluation of Two New MRI Techniques for Visualization of Peripheral Arterial Calcification; Gradient Echo with Flow Compensation and In-phase Echo Time as Well as 3D PETRA with Ultra-short TE.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019746.html