Transrectal ultrasound guided manipulation of the canine prostate with minimum intervention

Application of endoscopic ultrasound to the descending colon and rectum in normal dogs

Endoscopic ultrasound (EUS) is a medical procedure in which endoscopy is combined with ultrasonography (US) to compensate for problems associated with the transabdominal US such as large penetration depths, presence of intestinal gas, and acoustic shadowing. This prospective, method comparison, pilot study was performed to assess the feasibility of applying EUS in the colorectal region and to describe the typical EUS features of the descending colon and rectum in healthy dogs. Transabdominal US and EUS with or without the hydrosonography were applied to the descending colon and rectum in 10 clinically healthy Beagle dogs and wall thickness, visibility of the wall layers, and conspicuity of the mucosal and serosal surfaces of the intestinal wall were assessed. Endoscopic ultrasound enabled circumferential evaluation of the colorectal wall and provided better visibility of the wall layers and conspicuity of the mucosal and serosal surfaces without degradation of the image, even in the far-field portion of the colorectal wall, compared to US. Moreover, EUS provided the adequate image quality of the rectum, which was difficult to evaluate with US due to deep scan depth and acoustic shadowing by the pelvis. Meanwhile, the application of hydrosonography to EUS deteriorated the visibility of the wall layers and conspicuity of the intestinal wall. The results of this study demonstrate the feasibility of EUS to assess the colorectal region and its potential application for the evaluation of rectal masses or intrapelvic lesions that are inaccessible by the transabdominal US in dogs.

Behavior of tip-steerable needles in ex vivo and in vivo tissue

Robotic needle steering is a promising technique to improve the effectiveness of needle-based clinical procedures, such as biopsies and ablation, by computer-controlled, curved insertions of needles within solid organs. In this paper, we explore the capabilities, challenges, and clinical relevance of asymmetric-tip needle steering through experiments in ex vivo and in vivo tissue. We evaluate the repeatability of needle insertion in inhomogeneous biological tissue and compare ex vivo and in vivo needle curvature and insertion forces. Steerable needles curved more in kidney than in liver and prostate, likely due to differences in tissue properties. Pre-bent needles produced higher insertion forces in liver and more curvature in vivo than ex vivo. When compared to straight stainless steel needles, steerable needles did not cause a measurable increase in tissue damage and did not exert more force during insertion. The minimum radius of curvature achieved by prebent needles was 5.23 cm in ex vivo tissue, and 10.4 cm in in vivo tissue. The curvatures achieved by bevel tip needles were negligible for in vivo tissue. The minimum radius of curvature for bevel tip needles in ex vivo tissue was 16.4 cm; however, about half of the bevel tip needles had negligible curvatures. We also demonstrate a potential clinical application of needle steering by targeting and ablating overlapping regions of cadaveric canine liver.

ENDOSCOPIC ULTRASOUND OF THE CANINE ABDOMEN

The aim of this study was to develop a standardized procedure for examination of the canine abdomen using endoscopic ultrasound and to describe the organs and structures that could be identified transgastrically. The abdomen of four healthy dogs and two cadavers were examined with endoscopic ultrasound. Five anatomic landmarks were used for standardized imaging of the cranial abdomen. These were the portal vein, splenic head and body, duodenum, left kidney, and aorta. High-resolution images of the following organs and structures could be made: distal esophagus, gastric wall from the cardia to the pylorus, liver, caudal vena cava, hepatic lymph nodes, liver hilus, and associated vessels, trifurcation of the celiac artery as well as the path of its branches and the left pancreatic limb and body. Structures that were more difficult to image were the distal duodenum and right pancreatic limb, the entire jejunum, ileum, and cecum as well as the tail of the spleen. Endoscopic ultrasound allowed excellent visualization of the gastric wall and regional structures without interference with gas artefacts. Centrally located organs such as the pancreas could be well examined transgastrically with endoscopic ultrasound without interference by overlying intestinal segments as is common with transabdominal ultrasound.

Prostate lymphoscintigraphy for sentinel lymph node identification in canines: reproducibility, uptake, and biokinetics depending on different injection strategies

At present there are neither clinical nor experimental data available on the influence of technical details on the quality and reproducibility of prostate lymphoscintigraphy. Six adult fox hounds received repeated transrectal ultrasound guided intraprostatic injections of a technetium 99m labeled nanocolloid to prove the influence of different techniques of injection (one central injection in both prostate lobes vs two peripheral injections in both lobes) on tracer accumulation in sentinel lymph nodes (SLN) and other organs. The reproducibility of the favored technique was examined and in a last step it was subject to scrutiny following a reduction of the injected volume to 1% of the prostate volume. The number of scintigraphically visualized SLN varied between four and seven. They were located in the region of the internal and external iliac vessels, presacrally, paravesically, and directly paraprostatically. In five of six cases, the localization was reproducible both with the central application of an identical volume as well as with the volume reduced central injection. Tracer accumulation of SLNs and other organs varied enormously. We expect that with the combination of both injection techniques, even with the reduced injection volume, an optimized prostate lymphoscintigraphy will be the outcome.