Martin T. Rothman

Ultrasonic imaging of arterial structures using 3D solid modelling

A new type of vascular imaging system is presented which is designed for use in conjunction with percutaneous transluminal treatment techniques (balloon and laser angioplasty, atherectomy, etc.). Three-dimensional computer models of arterial sections are reconstructed in full volume-element (voxel) space from data acquired using a special-purpose, catheter-mounted ultrasound probe. The system is stand-alone, using commercially available computer hardware and specially created software. The software is equally compatible with source data from other modalities.<<ETX>>

3-D computer visualization of arteries and blood flow-in vitro and in vivo

An extension to previously described work on the representation of arterial structures using three-dimensional solid modeling is presented. Data acquired using a special-purpose catheter-mounted ultrasound probe are used to reconstruct 3-D computer models of arterial sections in vitro and in vivo. The images are reconstructed in full voxel space, which allows powerful software manipulation. Preliminary work on tissue differentiation using arterial models and color coding of the image is included. In addition to 3-D arterial visualization, early work on 3-D flow field representation is presented. It is concluded that the combining 3-D visualization of an artery with the presentation of the associated 3-D flow field will result in significant clinical benefit in the assessment of arterial disease.<<ETX>>

3-D visualization of arterial structures: tissue differentiation techniques

We have previously described a method for the 3-D visualisation of arterial structures using the voxel space approach to three-dimensional solid modelling. The system we use for intra-arterial imaging, in vitro and in vivo, is based on ultrasonic data, acquired with a purpose-built, catheter-mounted ultrasound probe. In this paper, we describe the methods employed for the reconstruction of 3-D models from these 2-D ultrasonic data and present preliminary work on tissue differentiation, using arterial models and colour-coding of the image.

3-D blood flow visualization

In this paper, we show how 3-D arterial visualisations may be combined with a 3-D representation of blood flow. We have developed techniques for the estimation and representation of the entire 3-D flow field for the section of artery under investigation. The flow fields are calculated from numerical solutions of the Navier-Stokes equations by a flow solver using a finite difference approach. In order to achieve this, both the profile of the inlet velocity waveform and the shape of the external grid structure of the flow field, derived from the 3-D solid model, are required. Clinically useful 3-D flow information is presented effectively by using a combination of 2-D cross-sectional displays.

Angioplasty under ultrasound

In this paper, we discuss some of the problems associated with attempting to image blood vessels using ultrasound from an intravascular approach. These include device miniaturisation, ultrasonic problems, difficulties with positioning and orientation of the device, and problems associated specifically with imaging catheters incorporating mechanically rotating parts. Some of the possible solutions are suggested, in terms of modification of transducer design, which may ultimately allow us to realise the goal of directing intraluminal treatment devices by means of intravascular, ultrasonic imaging.