3D image fusion for live guidance of stent implantation in aortic coarctation – magnetic resonance imaging and computed tomography image overlay enhances interventional technique

Non-invasive three-dimensional (3D) imaging belongs in routine practice in diagnosis and treatment planning of many congenital and acquired cardiovascular defects. Improvements in the development of fusion imaging software have led to the introduction of 3D reconstructed images for guidance of various transcatheter therapies, with three-dimensional rotational angiography (3DRA) being the most popular tool [1, 2]. A recently available 3D roadmap based on pre-registered computed tomography (CT) or magnetic resonance imaging (MRI) data sets promises reduction in contrast and radiation exposure along with shorter procedural times [3, 4]. We present our initial experience of this application with 3D image fusion (“merging”) for live guidance of stent implantation in coarctation of the aorta (CoA), using MRI applied with the HeartNavigator prototype (Philips Healthcare, Best, The Netherlands) and CT with the commercially available VesselNavigator (Philips Healthcare).
A 12-year-old boy presented to the outpatient clinic with arterial hypertension and intermittent headache already receiving -blocker therapy. Brachiocephalic hypertension was detectable with a gradient of 47–56 mm Hg between the arms and legs, and a reduced femoral pulse quality was present. Echocardiography showed normal biventricular function and left ventricular hypertrophy. The descending aorta showed a reduced pressure profile and diastolic “run-off” with no clearly detectable gradient. An MRI scan, performed with acquisition of a 3D whole heart sequence, demonstrated subatretic CoA distal to the left subclavian artery (LSA) with increased collateral flow. The aortic arch measured 10 × 12.5 mm, CoA diameter was 5 × 5 mm and the descending aorta distal to the narrowing was 17 × 19 mm.
Interventional therapy was performed under conscious sedation via femoral artery access. The three-dimensional whole heart sequence was uploaded to the workstation (HeartNavigator prototype, Philips), automatically segmented and manually corrected (Figure 1 A). For accurate fusion with live fluoroscopy the roadmap was manually aligned with two angiographies (10–15 ml) performed at a minimum 30° difference in angulation from the anterior-posterior projection (Figure 1 B). Initial hemodynamic measurements confirmed significant stenosis with a systolic pressure gradient of 50 mm Hg. A 28 mm long covered Cheatham Platinum (CP) stent (NuMed, USA) was mounted on a 12 mm Balloon-in-Balloon (BIB) catheter...


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