3-DIMENSIONAL VOLUMETRIC ULTRASOUND IMAGING OF ARTERIAL PATHOLOGY FROM 2-DIMENSIONAL INTRAVASCULAR ULTRASOUND - AN IN-VITRO STUDY

The objectives of this study were to evaluate: (1) the feasibility of generating three-dimensional (3-D) ultrasound (US) volumetric images o f arterial segments from intravascular (nr) US images by retaining ful l range of gray levels; (2) the feasibility of volumetric quantitation of various arterial wall pathology from the 3-D volume US images of a rterial segments. IVUS provides morphologic details of arterial wall d iseases. This is seen as variation in gray levels. However, when a 3-D US image is generated currently, the full range of gray levels is not utilized. This limits optimal assessment of arterial wall pathology. Sequential cross-sectional IVUS images from 11 arterial segments consi sting of various pathology were obtained in vitro by calibrated withdr awal of an IVUS catheter. These images were digitized by an 8 bit digi tizer to retain full 256 gray levels of brightness. 3-D volume generat ion was carried out using ''ANALYZE'' software. After the IVUS imaging , arterial segments were sectioned transversely in a 0.3-0.4 mm cross section and stained with hematoxylin, eosin and elastin. Geometrical m easurements and gross morphological changes of the arterial segments w ere noted and correlated with the corresponding section of the image f rom the three-dimensional volume. Arterial wall pathology, its extent and its effect on lumen geometry were easily appreciated in multiple t omographic sections of a 3-D volume image. Similarly, arterial wall pa thology was easily quantitated from 3-D volume. The above assessments were only feasible by retaining full range of gray levels in the 3-D v olume image. This study indicates that (1) it is feasible to generate a 3-D US volume image by retaining full range of gray levels from IVUS images, (2) retaining full range of gray levels allows optimal assess ment of arterial wall pathology and its extent in 3-D volume, and (3) IVUS allows quantitation of arterial wall pathology, and thereby one c an assess the effect of intervention.