For diagnosis and therapy planning in medical fields relating to hollow organs, especially in interventional cardiology, the process of obtaining information about the hollow organ from x-ray based imaging methods is known. These methods at best however only deliver information about the lumen, not about the wall structure of the vessel. Invasively applied imaging catheters, which include an imaging device, provide information about the wall structure. These imaging devices are based for example on ultrasound imaging (IVUS) or OCT (optical coherence tomography). In such cases mostly two-dimensional sectional images are obtained, with a 3D reconstruction of these two-dimensional catheter images not being possible a priori because of the unknown position and orientation in the hollow organ at the moment when the image is recorded. Different technical solutions have thus been proposed to allow the reconstruction of a 3D presentation of the hollow organ, especially of the vessel, to still be obtained.
In a method for fusion of angiography and IVUS (ANGUS) it is proposed that the withdrawal of an WUS catheter be recorded using a biplane x-ray system from two different directions. The position and orientation of the IVUS catheter at any given point in time can be determined from the two fluoroscopy images at an angle to each other obtained in this way. The continuous recording of fluoroscopy images leads in this case however to an extreme radiation load for the patient.
Alternatively the use of a location system has been proposed, cf. US 2002/0049375 A1, with a sensor or such like being mounted at the tip of the catheter of which the position and orientation is recorded by a location system positioned outside the body. The disadvantage of this method is that additional devices and special catheters are needed.
A further method for reconstruction of a 3D presentation of a blood vessel is proposed in an article by B. Martin-Leung, K. Eck, J. Bred no and T. Each, “X-IVUS: Integrated x-ray and IVUS system for the Cathay”, Medical Imaging 2005, Proc. of SPIE Vol. 5744, April 2005, pages 378 to 387. In this article two-dimensional WUS catheter images which belong to the same ECG phase of the heart cycle are sought out and a registration with previously recorded angiographic fluoroscopy images is undertaken. It is assumed here that the IVUS catheter tip is located in the center of the vessel lumen and moves at all times on this central line. However, two sources of error are then present:    a) On the one hand the catheter diameter is usually far smaller than the vessel diameter, i.e. the catheter will generally not be located in the center of the vessel lumen. This produces different effective withdrawal lengths, and in addition the alignment of the catheter can change during the withdrawal.    b) Another problem is that the orientation of the IVUS image plane relative to the vessel is unknown with this method. This means that distortions can arise for example during the reconstruction.
The article by Martin-Leung et al. does not disclose any reconstruction of a 3D presentation from the recorded IVUS catheter images, such a reconstruction would not be exact because of the sources of error identified under points a) and b) above.