Kidong Eom

Augmented reality intravenous injection simulator based 3D medical imaging for veterinary medicine

Augmented reality (AR) is a technology which enables users to see the real world, with virtual objects superimposed upon or composited with it. AR simulators have been developed and used in human medicine, but not in veterinary medicine. The aim of this study was to develop an AR intravenous (IV) injection simulator to train veterinary and pre-veterinary students to perform canine venipuncture. Computed tomographic (CT) images of a beagle dog were scanned using a 64-channel multidetector. The CT images were transformed into volumetric data sets using an image segmentation method and were converted into a stereolithography format for creating 3D models. An AR-based interface was developed for an AR simulator for IV injection. Veterinary and pre-veterinary student volunteers were randomly assigned to an AR-trained group or a control group trained using more traditional methods (n = 20/group; n = 8 pre-veterinary students and n = 12 veterinary students in each group) and their proficiency at IV injection technique in live dogs was assessed after training was completed. Students were also asked to complete a questionnaire which was administered after using the simulator. The group that was trained using an AR simulator were more proficient at IV injection technique using real dogs than the control group (P ≤ 0.01). The students agreed that they learned the IV injection technique through the AR simulator. Although the system used in this study needs to be modified before it can be adopted for veterinary educational use, AR simulation has been shown to be a very effective tool for training medical personnel. Using the technology reported here, veterinary AR simulators could be developed for future use in veterinary education.

The safety and efficacy of a new self-expandable intratracheal nitinol stent for the tracheal collapse in dogs.

To evaluate the potential utility of a self-expandable intratracheal nitinol stent with flared ends for the treatment of tracheal collapse in dogs, endotracheal stenting therapy was performed under fluoroscopic guidance in four dogs with severe tracheal collapse. During the 4 to 7 month follow-up, after stent implantation, clinical signs, including dyspnea and respiratory distress, dramatically improved in all dogs. The radiographs showed that the implanted stents improved the tracheal collapse, and there were no side effects such as collapse, shortening or migration of the stents. In conclusion, the self-expandable intratracheal nitinol stents provided adequate stability to the trachea and were effective for attenuating the clinical signs associated with severe tracheal collapse.

Radiographic and computed tomographic evaluation of experimentally induced lung aspiration sites in dogs.

This study was performed to radiographically examine the prevalence of aspiration sites and to evaluate their atomical correlation with the bronchial pattens. Ten healthy beagle dogs were repeatedly radiographed, at weekly intervals, in the left and right lateral, ventrodorsal (VD) and dorsoventral (DV) positions. Three mililiters of iohexol distilled with same volume of saline was infused into the tracheal inlet. Which lung lobe was aspirated was decided upon by the presence of a significant alveolar pattern due to the contrast medium. Alveolar patterns were identified at the left (100%) and right cranial lung lobes (77%) with the dogs in dependant lateral recumbency, at the right caudal lung lobe (71%) with the dogs in VD recumbency and at the right middle lung lobe (59%) with the dogs in DV recumbency, respectively. The anatomical correlation was evaluated by performing computed tomography. The right principal bronchus (165.8 ± 1.6°) was more straightly bifurcated than was the left principal bronchus (142.7 ± 1.8°, p < 0.01). In VD position, the right side lung had a greater opertunity to become aspirated. The ventrally positioned right middle lobar bronchial origin was more easily to be aspirated the other laterally positioned ones. We think that these anatomical characteristics can be one of the causes for aspiration pneumonia to occur more frequently in the right side lung.

Comparison of echocardiography with dual-source computed tomography for assessment of left ventricular volume in healthy Beagles

OBJECTIVE To compare echocardiographic measurements of left ventricular (LV) volume obtained via a modified Simpson or Teichholz method with those obtained via dual-source CT (DSCT). ANIMALS 7 healthy Beagles. PROCEDURES Each dog was anesthetized for DSCT; LV volume was determined from contrast-enhanced images of the LV lumen during all phases of contraction. Echocardiography was performed with dogs awake and anesthetized. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume, and ejection fraction were measured via a modified Simpson method and Teichholz method. Each dog was anesthetized twice with a 1-week interval between anesthetic sessions. RESULTS Results obtained while dogs were anesthetized revealed that the modified Simpson method underestimated LV volume (mean ± SD EDV, 24.82 ± 2.38 mL; ESV, 12.24 ± 1.77 mL), compared with that estimated by the Teichholz method (EDV, 32.57 ± 2.85 mL; ESV, 14.87 ± 2.09 mL) or DSCT (EDV, 34.14 ± 1.57 mL; ESV, 16.71 ± 0.76 mL). Ejection fraction (modified Simpson method, 48.53% ± 4.24%; Teichholz method, 54.33% ± 4.26%; DSCT, 51.00% ± 2.71%) differed significantly among the 3 methods. Echocardiographic results obtained while dogs were awake revealed that EDV, ESV, and stroke volume differed significantly between the modified Simpson and Teichholz methods. CONCLUSIONS AND CLINICAL RELEVANCE LV volume determined via the Teichholz method was more similar to that determined via DSCT than was the LV volume determined via the modified Simpson method. The modified Simpson method underestimated LV volume, compared with that obtained via the Teichholz method, in both anesthetized and awake dogs.

Use of canine small intestinal submucosa allograft for treating perineal hernias in two dogs.

Here, we describe two dogs in which canine small intestinal submucosa (SIS) was implanted as a biomaterial scaffold during perineal herniorrhaphy. Both dogs had developed severe muscle weakness, unilaterally herniated rectal protrusions, and heart problems with potential anesthetic risks. Areas affected by the perineal hernia (PH) located between the internal obturator and external anal sphincter muscles were reconstructed with naïve canine SIS sheets. In 12 months, post-operative complications such as wound infections, sciatic paralysis, rectal prolapse, or recurrence of the hernia were not observed. Symptoms of defecatory tenesmus also improved. Neither case showed any signs of rejection or specific immune responses as determined by complete and differential cell counts. Our findings demonstrate that canine SIS can be used as a biomaterial scaffold for PH repair in dogs.

Ultrasonographic evaluation of tracheal collapse in dogs

Tracheal ultrasonography was performed to measure the width of the tracheal ring shadow and to assess the clinical relevance of these measurements for identifying tracheal collapse. The first tracheal ring width (FTRW) and thoracic inlet tracheal ring width (TITRW) were measured on both expiration and inspiration. The mean of the FTRW width (129 dogs) was greater in expiration (10.97 ± 1.02 mm, p = 0.001) than that in inspiration (9.86 ± 1.03 mm). For 51 normal dogs, the mean of the TITRW width was greater in expiration (9.05 ± 1.52 mm, p = 0.001) than in inspiration (8.02 ± 1.43 mm). For 78 tracheal collapse dogs, the mean of the TITRW width was greater in expiration (15.89 ± 1.01 mm, p = 0.001) than in inspiration (14.85 ± 1.17 mm). The TITRW/FTRW ratio of the normal dogs was higher (p = 0.001) in expiration (0.81 ± 0.09) than that in inspiration (0.79 ± 0.10). When compared between the normal and tracheal collapse dogs, the TITRW/FTRW ratio was also increased (p = 0.001) both in expiration (1.54 ± 0.09) and inspiration (1.47 ± 0.08), respectively. Based on these results, the cutoff level of the TITRW/FTRW ratio was statistically analyzed according to the receiver operating characteristic curve and it could be set at 1.16 in expiration and at 1.13 in inspiration. We have demonstrated that tracheal ultrasonography is a useful technique for the evaluation of tracheal collapse and it can be a supportive tool together with the radiographic findings for making the correct diagnosis.

Diffusion tensor imaging of white and grey matter within the spinal cord of normal Beagle dogs: Sub-regional differences of the various diffusion parameters

Diffusion tensor imaging (DTI) is an advanced diffusion weighted imaging technique that can identify early stage lesions and Wallerian degeneration within the spinal cord; these changes are difficult to recognise on conventional magnetic resonance imaging (MRI). The only DTI parameters previously investigated in dogs are fractional anisotropy and mean diffusivity (MD). The aim of this study was to evaluate multiple DTI parameters in sub-regional areas of the spinal cord in normal Beagles. All imaging data were obtained from the lumbar spinal cord (L1-L3) of ten normal dogs using a 3 Tesla MRI scanner. Transverse multi-shot echo planar imaging sequences (b values = 0 and 800 s/mm(2); 12 directions) were used for DTI. Regions of interest were selected from sub-regions of the white and grey matter, and from the whole spinal cord, in the transverse plane in all DTI maps. The DTI parameters in spinal cord sub-regions in the transverse plane were significantly different amongst the white matter, grey matter and whole spinal cord (P < 0.05 for all DTI parameters except MD), as well as between white matter sub-regions (P < 0.05 for most DTI parameters except radial diffusivity, MD and planar index). DTI-based sub-regional analysis of white and grey matter may be useful for regional evaluation of the dog spinal cord.

Contrast echocardiography to assess left ventricular volume and function in Beagle dogs: comparison with 3-Tesla dual source parallel cardiac magnetic resonance imaging.

This study was performed to evaluate the effect and feasibility of contrast echocardiography (CE) compared with unenhanced echocardiography (UE) and cardiac magnetic resonance imaging (CMRI) to assess left ventricular (LV) volume and function, including end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) in six healthy Beagles. When the dogs were conscious, LV measurements using CE were significantly higher than those obtained using UE, except for EF, and were similar to the values obtained using CMRI. Additionally, EDV, SV, and EF obtained using UE from anesthetized dogs were significantly lower than those obtained using CE or CMRI. Measurements of EDV, SV and EF using CE were not significantly different from the corresponding measurements obtained using CMRI (31.13±2.18 vs. 32.88±1.17 mL, 18.41±1.25 vs. 17.92±0.96 mL, 59.29±2.29% vs. 53.33±1.69%, respectively). Inter-observer agreements for UE (0.74±0.05) were lower than those for CE (0.80±0.04) and CMRI (0.92±0.03). In conclusion, LV function was assessed reproducibly using CE, and the measurements obtained were consistent with reference standard measurements obtained using CMRI. Measurements made using CE agreed more closely with CMRI than those made using UE.

Doppler ultrasonographic evaluation of renal arterial resistive and pulsatility indices in overhydrated Beagles

OBJECTIVE To determine renal arterial resistive index (RI) and pulsatility index (PI) and clinical signs of overhydration induced by IV administration of saline (0.9% NaCl) solution and to assess RI and PI as variables for monitoring of dogs to detect overhydration. ANIMALS 10 clinically normal Beagles. PROCEDURES Each dog received saline solution at a maintenance rate (2.5 mL/kg/h) and a rate 3 times that of the maintenance rate (overhydration rate; 7. 5 mL/kg/h). Values of RI and PI were determined with pulsed-wave Doppler ultrasonographic examination of renal interlobar or arcuate arteries before saline solution administration, every hour during 5 hours of administration, and 1 hour after administration was stopped. RESULTS No significant changes in RI or PI were detected during administration of saline solution at the maintenance rate. However, RI (starting 1 hour after the beginning of fluid administration [mean ± SD value, 0.589 ± 0.012]) and PI (starting 2 hours after the beginning of fluid administration [value, 0.867 ± 0.052]) were significantly lower during administration at the overhydration rate than they were during administration at the maintenance rate. Clinical signs of overhydration were observed in all dogs starting 4 hours after the beginning of fluid administration at the overhydration rate. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated overhydration of dogs caused significant decreases in RI and PI prior to detection of clinical signs of overhydration. Ultrasonographic determination of renal arterial RI and PI seemed to be a noninvasive and sensitive method for evaluation of overhydration in dogs.

Effect of Harderian adenectomy on the statistical analyses of mouse brain imaging using positron emission tomography.

Positron emission tomography (PET) using 2-deoxy-2-[18F] fluoro-D-glucose (FDG) as a radioactive tracer is a useful technique for in vivo brain imaging. However, the anatomical and physiological features of the Harderian gland limit the use of FDG-PET imaging in the mouse brain. The gland shows strong FDG uptake, which in turn results in distorted PET images of the frontal brain region. The purpose of this study was to determine if a simple surgical procedure to remove the Harderian gland prior to PET imaging of mouse brains could reduce or eliminate FDG uptake. Measurement of FDG uptake in unilaterally adenectomized mice showed that the radioactive signal emitted from the intact Harderian gland distorts frontal brain region images. Spatial parametric measurement analysis demonstrated that the presence of the Harderian gland could prevent accurate assessment of brain PET imaging. Bilateral Harderian adenectomy efficiently eliminated unwanted radioactive signal spillover into the frontal brain region beginning on postoperative Day 10. Harderian adenectomy did not cause any post-operative complications during the experimental period. These findings demonstrate the benefits of performing a Harderian adenectomy prior to PET imaging of mouse brains.