Our method offers the possibility of determining the C-arm incidence with the least foreshortening for a selected segment of the coronary vessels, segmented in a pre-operative cardiac CT dataset. In order to assist in stent length selection, the length of a vascular lesion can be measured in 3D along the centerline of the curved vessel. During the intervention the stored C-arm viewing incidence can be recalled, and the C-arm can be automatically steered to the corresponding angles.

Furthermore our method allows rendering of a curved Multi-Planar Reformating (MPR) and a 3D visualization of the coronary arteries, both following in real-time the direction of the viewing incidence of the C-arm. Based on this automatically registered reference image of the CT data, it is possible to steer the C-arm, without using additional contrast medium or X-ray radiation.

TrueView map

Spatial foreshortening is the distortion of geometrical structures (e.g. vessel) when depicted at an angle. Foreshortening of the vessel geometry in X-ray images makes it difficult to asses their true length, and therefore it is preferable to select X-ray projection views that have minimal foreshortening for the vessel segments of interest [2].
The TrueView map [3,4] can be used to plan a C-arm position that provides a view with minimal foreshortening of the selected coronary artery segment.

Follow C-arc

The orientation of the coordinate systems of the CT dataset and the X-ray C-arm are registered, based on the DICOM information.
When the Follow C-arc mode is active, the viewing incidence of the CT dataset is matched in real time with the current rotation and angulation of the C-arm geometry. This allows using the view on the CT dataset to predict an optimal working position for the C-arc without actually using X-ray.
The counterpart of this function is called 3D APC (Automatic Positioning Control), which allows the C-arc to be moved to a viewing incidence corresponding to the 3D rendering of the CT dataset. Desired working positions can be planned (e.g. using the TrueView map) and stored pre-interventionally and later recalled during the procedure when needed.

Curved MPR

A curved MPR [5] representation of the vessels is available, and helps the physician to find the best view on the stenosis and the surrounding calcified plaque. Since the curved MPR is coupled to the 3D view of the CT dataset, it will pursue the 3D orientation in the follow C-arc mode.
The curved MPR is complemented with a cross-sectional view and a measurement tool, providing true length along the 3D centerline as well as cross-sectional measurements.

Virtual X-ray

An X-ray angiography -like representation of the coronary arteries, based on the CT dataset, is provided, in order to assist the physician while planning the optimal views. This type of visualization allows a better impression of the X-ray angiographic view that will be generated from a particular viewing incidence.

Overlay

An overlay visualization of the CT dataset on the X-ray image can be presented for guidance during the procedure. This overlay application is preceded by a registration step, which correlates the C-arm coordinate system and the CT coordinate system.