Evaluation of the efficacy of a novel three-dimensional (3D) rectal probe with a thinner diameter

Aims: We have studied a manufactured rigid rectal probe enabling three-dimensional (3D) scanning since Jun 2001. The novel 3D rectal probe (7.5MHz, XRU-75M-DP2, Olympus) has a 15-mm outside diameter, and the form of its tip and the hand-operated swiveling part have been modified. When the rectal probe is used, there may be multiple echoes around its surface that can obscure the image, in which case a standoff produced by the balloon or the acoustic silicone coupler can be useful.

Aims: The aims of this study were to assess the resolution of the 3D rectal probe by performing basic examinations with or without the silicone coupler, and to assess the value of the rectal probe in clinical cases.

Materials and Methods: As a basic experiment to evaluate the influence of the multiple echoes, we compared scanning by the 3D rectal probe under water immersion with scanning by the probe covered by a silicone tube, of specimens excised from normal large intestine. We used the balloon method to scan eighteen rectal lesions through deaerated water; we inserted the 3D rectal probe covered by a silicone tube and scanned from the upper to the lower rectum.

Results: A silicone tube attached with the probe could facilitate the scanning by suppressing the multiple echos, and enable the analysis of the structures from the mucous membrane to the submucosal layer. The diameter of the new modified probe is thinner, permitting easy insertion of the probe into the anal canal even surrounded by a silicone tube. All rectal lesions could be detected, except one lesion on the rectosigmoid (Rs) because the probe was too short to reach. There were no complications during this procedure.

Conclusion: The probe with a silicone tube attached could be used to evaluate of proctorectal lesions.