Antegrade and retrograde CT urethrography with virtual urethroscopy in a dog with urethral narrowing after bilateral triple pelvic osteotomy.

An 8-month-old, castrated male Golden Retriever was unable to urinate without catheterization after a single-session bilateral triple pelvic osteotomy. To determine the cause, a retrograde urethrography was performed, but the results were equivocal. Antegrade (voiding by abdominal compression with heavy material) and retrograde CT urethrography were performed with virtual urethroscopy and revealed that the urethral diameter was narrowed near the pubic bone remnants due to pelvic canal narrowing. After corrective surgery, the patient was able to urinate normally. A combination of antegrade and retrograde CT urethrography with virtual urethroscopy was helpful for guiding surgical decision-making in this patient.

Proper fraction of inspired oxygen for reduction of oxygen-induced canine cerebrospinal fluid hyperintensity on fluid attenuation inversion recovery sequence using low-field magnetic resonance imaging.

Oxygen-induced cerebrospinal fluid (CSF) hyperintensity artifact is inevitable in fluid attenuation inversion recovery (FLAIR) magnetic resonance (MR) images of anesthetized animals. This experimental study aimed to confirm the occurrence of this artifact on low-field magnetic resonance imaging (MRI), and to determine the fraction of inspired oxygen (FiO2) that is safe and does not induce this artifact in canine brain MRI. Six healthy dogs underwent brain FLAIR MR scans under general anesthesia with 21%, 30%, 50%, 70%, and 100% FiO2. The signal intensity (SI) ratio was calculated as the SI of CSF spaces divided by that of normalizing regions. The SI ratios of 21% FiO2 images were significantly different from those of 100% FiO2 images, indicating the presence of artifacts on 100% FiO2 images. The SI ratios of 30% FiO2 images were not significantly different from those of 21% FiO2 images for any of CSF spaces. However, they were significantly different from those of 100% FiO2 images in the cerebral sulci, third ventricle, interpeduncular cistern, mesencephalic aqueduct, and subarachnoid space at the level of the first cervical vertebra (P<0.05). All dogs had normal partial pressure of arterial oxygen (PaO2) during inhalation of 30% FiO2, while two dogs had low PaO2 during inhalation of 21% FiO2. Our findings support the hypothesis that high FiO2 induces CSF hyperintensity artifact on low-field FLAIR MR images in dogs. FiO2 of 30% is appropriate for obtaining brain FLAIR MR images with fewer artifacts in dogs.

Esophageal insufflation computed tomography in clinically normal dogs.

OBJECTIVE To assess the feasibility of esophageal insufflation CT (EICT) for evaluation of the esophagus in dogs. ANIMALS 7 clinically normal adult Beagles. PROCEDURES Each dog was anesthetized twice with 1 week between anesthesia sessions. Dogs were positioned in sternal recumbency during all CT scans. During the first anesthesia session, a CT scan was performed before the esophagus was insufflated (insufflation pressure, 0 mm Hg) and unenhanced and contrast-enhanced EICT scans were performed after CO2 was insufflated into the esophageal lumen to achieve a pressure of 5 mm Hg. For the contrast-enhanced scan, each dog received iohexol (600 mg/kg, IV), and the scan was performed 30 seconds later. During the second anesthesia session, unenhanced and contrast-enhanced EICT scans were performed in the same manner except the insufflation pressure achieved was 10 mm Hg. The esophageal luminal cross-sectional area and wall thickness were measured at each of 5 segments, and mean values were compared among the 3 insufflation pressures and between unenhanced and contrast-enhanced images. RESULTS Mean esophageal luminal cross-sectional area increased and esophageal wall thickness decreased as insufflation pressure increased. Measurements did not differ significantly between unenhanced and contrast-enhanced images. The stomach became distended with CO2 at an insufflation pressure of 10 mm Hg but not at 5 mm Hg. No adverse effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested EICT was feasible for esophageal evaluation in dogs. Further research is necessary to determine the optimal insufflation pressure for the procedure and its diagnostic efficacy in diseased patients.

Comparing Stability of Mandibular Setback Versus 2-Jaw Surgery in Class III Patients With Minimal Presurgical Orthodontics.

PURPOSE: The aim of this study was to compare treatment time and skeletal stability between mandibular setback surgery (MS) and 2-jaw surgery (2J) with minimal presurgical orthodontics (MPO) in patients with skeletal Class III. MATERIALS AND METHODS: One hundred ninety-five patients who underwent orthognathic surgery were enrolled in this retrospective cohort study. Consecutive patients were selected based on standardized inclusion criteria: Class III malocclusion with mandibular prognathism, surgery type, and presurgical orthodontics with non-extraction for less than 6 months (MPO). Lateral cephalograms were taken before surgery (T0), 1 month after surgery (T1), and at debonding (T2). To evaluate surgical changes (T0 to T1) and postsurgical changes (T1 to T2) in skeletodental tissue, linear, angular, and dental measurements were analyzed using paired t test and independent t test. RESULTS: Thirty-one patients were allocated to the MS-MPO group (n = 16) and the 2J-MPO group (n = 15). The 2J-MPO group showed a shorter duration of postsurgical orthodontic and total surgical and orthodontic treatment than the MS-MPO group. Although the 2J-MPO group exhibited advancement and superior impaction of the maxilla from T0 to T1, posterior movement with clockwise rotation of the mandible between the 2 groups did not show a statistical difference. In addition, from T1 to T2, the MS-MPO and 2J-MPO groups presented forward and upward movement and counterclockwise rotation of the mandible, but no intergroup difference was found. CONCLUSIONS: The MS-MPO and 2J-MPO groups showed similar horizontal and vertical mandibular stability. However, the 2J-MPO group presented a shorter surgical and orthodontic treatment time than the MS-MPO group.

Comparative evaluation of the sliding plate technique for fixation of a sagittal split ramus osteotomy: finite element analysis.

OBJECTIVE: This study evaluated the stress distribution of the sliding plate (SP) and conventional miniplate (CM) fixation techniques of a sagittal split ramus osteotomy (SSRO) using 3-dimensional (3-D) finite element analysis. STUDY DESIGN: Four 3-D finite element models according to the number and shape of screw holes in the plate were simulated, and the von Mises stress was analyzed: SP with 2 round and 2 oval holes (SP-2 R2 O), SP with 2 round and 1 oval holes (SP-2 R1 O), CM with 4 round holes (CM-4 R), and CM with 3 round holes (CM-3 R). RESULTS: The fixation technique with CM-4 R showed a better stress distribution than CM-3 R, which in turn showed better results compared to the 2 different SPs. SP-2 R2 O showed the worst stress distribution in the bone and fixation components. CONCLUSIONS: The results suggest that the SP-2 R2 O technique increases the stress distribution of the plate and screws, which may reduce the stability of fixation after SSRO.

Evaluation of soft tissue changes around the lips after bracket debonding using three-dimensional stereophotogrammetry.

OBJECTIVE: To evaluate the changes in soft tissue around the lips after orthodontic bracket debonding using three-dimensional (3-D) stereophotogrammetry. MATERIALS AND METHODS: 3-D facial images of 20 subjects (10 men and 10 women; mean age, 26.81 ± 7.23 years) were taken with a white light scanner before and after debonding the labial brackets. Two images acquired from each subject were superimposed, and 15 soft tissue landmarks around the lips were plotted and analyzed. Statistical analysis was performed using both paired and independent t-tests (P < .05). RESULTS: There were no significant changes in position of any landmark on the x (left-right)- or y (vertical)-axes after removal of the brackets. However, the landmarks in the oral commissures and lower lip (LLP, -0.55 mm; Li, -0.44 mm; Ch-L, -0.56 mm, all P < .05) on the z (anteroposterior)-axis showed statistically significant differences. There were no significant positional changes of most landmarks on the x-, y-, or z- axes after bracket removal among the various genders and lip thicknesses. CONCLUSIONS: There was a slight retrusion in the oral commissure and lower lip areas after debonding, but no changes were found in the upper lip area. This study showed that 3-D stereophotogrammetry can be useful in evaluating facial soft tissue changes in orthodontic patients.