Background and Study Aims: The Olympus EU-IP2 three-dimensional endoscopic ultrasound (3D-EUS) imaging system makes it possible to display tumors in three dimensions and estimate their volume.
Materials and Methods: Experimental and clinical studies of the volume estimation function of the Olympus EU-IP2 system was carried out to evaluate its accuracy and assess the extent of tumor shrinkage caused by fixation, dehydration, and staining.
Results. In the experimental studies, compared with the actual volume of a 1000-mm3 gelatin column, the estimated volume was found to be equivalent to 114 ± 1.8 % with the 3R probe and 143 ± 0.8 % with the 2R probe (mean plus or minus standard deviation). The mean estimated volume of tumor models was 127 ± 8.5 % with the 3R probe and 131 ± 6.8 % with the 2R probe. Greater distance from the probe was associated with a greater degree of error than the target object’s size, angle, or the number of traces of its outline made. In the clinical studies, compared with the histologically determined tumor volume (100 %), the mean estimated tumor volume was 178 ± 48.2 % in situ, 168 ± 31.3 % in resected specimens, and 137 ± 31.5 % after fixation. Fixation, dehydration, and staining were thus associated with tumor shrinkage.
Conclusions: The volume of gastrointestinal lesions can be estimated by 3D-EUS, although it is overestimated in comparison with actual values. 3D-EUS also allows direct comparisons to be made between the tumor volume before surgery and the volume of fixed pathological specimens, so that the rate of tumor shrinkage can be estimated.
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M. Kida, M. D.
Dept. of Gastroenterology, Kitasato University East Hospital
2-1-1 Azamizodai, Sagamihara City · Kanagawa 228-8520 · Japan
Fax: +81-42-749-8690
Email: m-kida@kitasato-u.ac.jp
