Potential of intraluminal ultrasound for angioplasty guidance

The manifestation of atherosclerotic lesions in arteries can vary from asymptomatic thickening in the vessel wall to complete occlusion. Experimental studies on non-human primates¹ and on human subjects^2-4 indicate that atherosclerotic lesions may progress without a reduction in luminal diameter because of dilatation of the arterial wall. Although angiography has been considered the 'gold standard' for visualization of the arterial tree and detection of luminal narrowing, it does not demonstrate arterial wall thickening or morphology. Moreover, the measurement of luminal diameter of the same lesion can vary considerably depending on the plane of projection of the x-ray beam. This is attributed to the eccentric nature of the residual lumen in an atherosclerotic vessel.⁵ Extraluminal B-mode real time imaging has the feasibility of demonstrating arterial lumen and arterial wall thickness.⁶ However, it is still in some instances limited by inadequate resolution and image quality. Intraluminal ultrasound using a phased array or rotating transducer gives better definition of the vessel wall and luminal diameter as it is not limited by the tissue interposed between the vessel and the probe in transcutaneous devices. This paper demonstrates further experience with intravascular ultrasound as a diagnostic tool using B-mode real time imaging.