Browse

You are looking at 1 - 10 of 194 items for :

  • Diagnostic Imaging x
  • Refine by Access: All Content x
Clear All

Abstract

OBJECTIVE

To characterize the anatomic location of the esophageal ostium relative to the rima glottidis in adult Labrador Retrievers with the use of CT.

ANIMALS

98 CT scans of 75 adult Labrador Retrievers.

PROCEDURES

A search of the medical records database identified records of Labrador Retrievers that underwent CT of the head and neck between January 1, 2015, and December 31, 2018. Evaluators, blinded to each other's results, reviewed CT images and measured esophageal area at the level of the rima glottidis. For each dog, the left esophageal percentage (LEP) was calculated as the esophageal area left of the rima glottidis midline divided by the overall esophageal area at that level. Variables (age, sex, patient position, intubation status, and maxillary support during CT) were evaluated for association with LEP. The CT images of dogs that had multiple scans were assessed for within-patient variance.

RESULTS

Mean LEP was 56.2 ± 18.1% for all dogs. Only right lateral recumbency was significantly associated with LEP, with a lower LEP for dogs positioned in right lateral recumbency (42.4 ± 12.7%), compared with left lateral (63.0 ± 7.4%) or sternal (57.3 ± 18.8%) recumbency. No association was detected between LEP and other variables assessed. Eleven dogs had multiple CT scans; within-patient variance for LEP was ± 26.6%.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that, although most dogs had an LEP > 50%, the esophageal ostium was fairly centrally located in most dogs and may be more mobile than previously thought. Additional research is warranted to assess this mobility and whether the esophageal ostium location, relative to the larynx, affects the incidence of aspiration pneumonia in dogs undergoing surgical treatment for geriatric-onset laryngeal paralysis and polyneuropathy.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To compare shear-wave velocities (SWVs) with shear-wave elastography of various peripheral lymph nodes (LNs).

ANIMALS

11 healthy Beagles.

PROCEDURES

For each dog, bilateral mandibular, medial retropharyngeal, superficial cervical, axillary, superficial inguinal, and popliteal LNs were evaluated with shear-wave elastography in sagittal and transverse scanning planes. Depth of each lymph node was recorded, and intra- and interobserver reliability was determined.

RESULTS

SWVs for all LNs were significantly higher in the sagittal scanning plane, compared with those in the transverse scanning plane. The SWV of the most superficial LN, the mandibular LN, was significantly higher, compared with that for the other LNs, except for the medial retropharyngeal LN. The SWV of the deepest LN, the medial retropharyngeal LN, was as high as that for the mandibular LN. Intra- and interobserver reliability was excellent.

CONCLUSIONS AND CLINICAL RELEVANCE

SWVs for normal peripheral LNs of Beagles may serve as a reference to compare with those for other breeds and diseased LNs. Scanning plane, LN depth, and interfering tissues between the LN and the transducer may affect SWV. Shear-wave elastography may not be operator dependent.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To assess the diagnostic value of the ultrasonographic description of a splenic mass or nodule as cavitated in dogs with nontraumatic hemoabdomen.

ANIMALS

106 dogs with a nontraumatic hemoabdomen that underwent abdominal ultrasonography and splenectomy with histologic examination of splenic lesions between 2005 and 2018.

PROCEDURES

Medical records were reviewed for abdominal ultrasonographic and histologic findings. Diagnostic performance of ultrasonographic description of a splenic mass or nodule as cavitated as evidence of hemangiosarcoma or any malignancy was evaluated.

RESULTS

Ultrasonographic description of splenic lesions as cavitated had poor diagnostic utility in predicting presence of hemangiosarcoma or malignancy. Sensitivity and specificity of this test were 41.9% (95% CI, 30.5% to 54.3%) and 51.2% (95% CI, 36.8% to 65.4%), respectively, for detecting hemangiosarcoma, with positive and negative predictive values of 55.3% (95% CI, 41.2% to 68.6%) and 37.9% (95% CI, 26.6% to 50.8%), respectively. Results were similar for detecting malignancy. Cavitated lesions outside of the spleen were too rare for statistical analysis to be of value.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that relying on ultrasonographic description of cavitation to diagnose splenic lesions as malignant in dogs with nontraumatic hemoabdomen is unfounded. Other preoperative diagnostic tests may be more valuable in determining short- and long-term prognoses.

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To describe the technique and assess the diagnostic potential and limitations of tomosynthesis for imaging of the metacarpophalangeal joint (MCPJ) of equine cadavers; compare the tomosynthesis appearance of pathological lesions with their conventional radiographic, CT, and MRI appearances; and evaluate all imaging findings with gross lesions of a given MCPJ.

SAMPLE

Distal portions of 4 forelimbs from 4 equine cadavers.

PROCEDURES

The MCPJs underwent radiography, tomosynthesis (with a purpose-built benchtop unit), CT, and MRI; thereafter, MCPJs were disarticulated and evaluated for the presence of gross lesions. The ability to identify pathological lesions on all images was assessed, followed by semiobjective scoring for quality of the overall image and appearance of the subchondral bone, articular cartilage, periarticular margins, and adjacent trabecular bone of the third metacarpal bone, proximal phalanx, and proximal sesamoid bones of each MCPJ.

RESULTS

Some pathological lesions in the subchondral bone of the third metacarpal bone were detectable with tomosynthesis but not with radiography. Overall, tomosynthesis was comparable to radiography, but volumetric imaging modalities were superior to tomosynthesis and radiography for imaging of subchondral bone, articular cartilage, periarticular margins, and adjacent bone.

CONCLUSIONS AND CLINICAL RELEVANCE

With regard to the diagnostic characterization of equine MCPJs, tomosynthesis may be more accurate than radiography for identification of lesions within subchondral bone because, in part, of its ability to reduce superimposition of regional anatomic features. Tomosynthesis may be useful as an adjunctive imaging technique, highlighting subtle lesions within bone, compared with standard radiographic findings.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To assess the feasibility of blood oxygen level–dependent (BOLD) MRI for measurement of the renal T2* relaxation rate (R2*; proxy for renal oxygenation) before and after furosemide administration and to evaluate the reliability and repeatability of those measurements in healthy dogs.

ANIMALS

8 healthy adult Beagles (4 males and 4 females).

PROCEDURES

Each dog was anesthetized and underwent BOLD MRI before (baseline) and 3 minutes after administration of furosemide (1 mg/kg, IV) twice, with a 1-week interval between scanning sessions. Mapping software was used to process MRI images and measure R2* and the difference in R2* (∆R2*) before and after furosemide administration. The intraclass correlation coefficient was calculated to assess measurement reliability, and the coefficient of variation and Bland-Altman method were used to assess measurement repeatability.

RESULTS

Mean ± SD baseline R2* in the renal medulla (24.5 ± 3.8 seconds−1) was significantly greater than that in the renal cortex (20.6 ± 2.7 seconds−1). Mean R2* in the renal cortex (18.6 ± 2.6 seconds−1) and medulla (17.8 ± 1.5 seconds−1) decreased significantly after furosemide administration. Mean ∆R2* in the medulla (6.7 ± 2.4 seconds−1) was significantly greater than that in the renal cortex (2.1 ± 0.7 seconds−1). All R2* and ∆R2* values had good or excellent reliability and repeatability, except the cortical ∆R2*, which had poor repeatability.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that BOLD MRI, when performed before and after furosemide administration, was noninvasive and highly reliable and repeatable for dynamic evaluation of renal oxygenation in healthy dogs.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate the efficacy of a phospholipid-stabilized sulfur hexafluoride microsphere (SHM) contrast agent and water for hydrosonography of the upper portion of the gastrointestinal tract of dogs.

ANIMALS

12 healthy adult Beagles.

PROCEDURES

In a crossover study, each dog was anesthetized and underwent noncontrast ultrasonography then hydrosonography following administration of tap water (30 mL/kg) without (water method) or with SHM (0.1 mL; SHM method) via an orogastric tube. There were at least 3 days between hydro-sonographic procedures. Wall thickness, wall layer definition, conspicuity of the mucosal-luminal interface, and image quality were evaluated separately in the near and far fields for the gastric cardia, body, and pylorus and descending duodenum and compared among the 3 scanning methods.

RESULTS

Mean wall thickness measurements did not differ significantly between the water and SHM methods at any location except the far-field gastric cardia where the mean wall thickness for the SHM method was less than that for the water method. In general, the SHM method improved wall layer definition and conspicuity of the mucosal-luminal interface of structures in the near field, compared with noncontrast method. The water and SHM methods both resulted in superior image quality relative to the noncontrast method for the near-field gastric cardia, far-field gastric cardia, and far-field duodenum.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that, for dogs, gastrointestinal hydrosonography by use of the SHM method improved wall layer definition and mucosal conspicuity, particularly in near-field images of the upper portion of the gastrointestinal tract. (Am J Vet Res 2021;82:712–721)

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVES

To compare the use of curvilinear-array (microconvex) and phased-array transducers for ultrasonographic examination of the lungs in dogs.

ANIMALS

13 client-owned dogs with left-sided congestive heart failure.

PROCEDURES

In a prospective methods comparison study, 24 ultrasonographic examinations of the lungs (4 sites/hemithorax) were performed with both curvilinear-array and phased-array transducers at 3 clinical time points. Two observers independently assessed the number of B lines (scored per site and in total), number of sites strongly positive for B lines (ie, those with > 3 B lines/site), and image quality (scored on a 5-point scale). Analyses included assessment of interobserver agreement with κ analysis, comparison of quality scores between transducers with mixed-effects modeling, and investigation of agreement and bias for B-line data and quality scores between transducers with Passing-Bablok regression.

RESULTS

Interobserver agreement for total B-line scores and number of strong-positive sites was excellent (κ > 0.80) for both transducers. There was no evidence of analytic bias for the number of B lines or strong-positive sites between transducers. Interobserver agreement for image quality scores was moderate (κ, 0.498 and 0.517 for the curvilinear-array and phased-array transducers, respectively). Both observers consistently assigned higher-quality scores to curvilinear-array images than to phased-array images.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated both curvilinear-array (microconvex) and phased-array transducers can be used by experienced sonographers to obtain diagnostic ultrasonographic images of the lungs in dogs with acute or resolving left-sided congestive heart failure and suggested the former transducer may be preferred, particularly to aid identification of anatomic landmarks for orientation.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To use CT-derived measurements to calculate a shape constant (K constant) and create a formula to calculate body surface area (BSA) on the basis of body weight in bearded dragons (Pogona vitticeps).

ANIMALS

12 adult client-owned bearded dragons that underwent CT between December 4, 2019, and April 2, 2020.

PROCEDURES

Each bearded dragon in this prospective cohort study underwent physical examination, body weight measurement, and CT. A 3-D surface model was then reconstructed from CT data with available software and used for BSA calculations. Animals were considered collectively and grouped by sex and age. Nonlinear regression analysis of BSA versus body weight was performed, and a species-specific formula was derived for calculating BSA in bearded dragons.

RESULTS

Mean age, body weight, and CT-derived BSA were 2.1 years, 356 g, and 580 cm2. The calculated K constant was 11.6 (R2 = 0.994; SE = 0.275) for the 12 bearded dragons, and the CT-derived BSA formula was as follows: BSA in cm2 = 11.6 × (body weight in g)2/3. The K constant differed substantially for bearded dragons grouped by age (12.1 for younger [between 1 and ≤ 2 years of age; n = 8] vs 10.9 for older [> 2 years of age; 4] animals) but did not differ on the basis of sex.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that because the K constant for bearded dragons in the present study was larger than the preexisting K constant of 10 used for reptiles or the various K constants established for some companion mammals, doses of chemotherapeutic drugs needed to treat affected bearded dragons may be higher than previously thought.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To compare qualitative features and quantitative parameters of 2 contrast agents (sulfur hexafluoride microbubbles [SHM; SonoVue] and perfluoro-butane [PFB; Sonazoid]) for performance of contrast-enhanced ultrasonography (CEUS) of the pancreas in dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

In a crossover study design, CEUS of the pancreas was performed twice in each dog, once with SHM and once with PFB, in random order with at least 3 days between examinations. The recorded cine images were qualitatively assessed for homogeneity of pancreatic enhancement and conspicuity of the pancreatic signal relative to the background. For the quantitative assessment, circular regions of interest were placed over the pancreatic body, and a time-intensity curve was obtained. For each region of interest, CEUS parameters including peak intensity (PI), time to peak pancreatic enhancement, area under the curve (AUC), and wash-in rate were obtained.

RESULTS

The homogeneity of the pancreatic parenchyma was not significantly different between contrast agents. The signal conspicuity relative to background noise was significantly higher with PFB than with SHM. Mean values of PI, wash-in rate, and AUC were significantly higher with PFB than with SHM. Time to peak enhancement was not significantly different between contrast agents.

CONCLUSIONS AND CLINICAL RELEVANCE

Pancreatic CEUS with SHM and PFB produced similar homogeneity scores, but only PFB provided excellent signal conspicuity. Perfluorobutane produced higher values of PI, wash-in rate, and AUC. Findings indicated that PFB can provide homogeneous and strong enhancement of the pancreas during CEUS in healthy dogs and that pancreatic CEUS parameter values differ with the contrast agent used.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate radiographic variables for correlation with splenic size as estimated with CT in cats.

ANIMALS

38 healthy adult cats.

PROCEDURES

The width and height of the splenic head and total length, segmental length, and width of the spleen were measured on radiographic and CT images obtained from 10 cats in prospective, exploratory experiments. Distance between the splenic head and left kidney, anatomic locations of the head and tail of the spleen, and CT-derived splenic volume were also assessed. Correlation and agreement between radiographic and CT measurements and interobserver agreement for measurements with each method were determined. A retrospective evaluation of radiographs obtained without sedation or anesthesia for 28 cats was performed to establish preliminary guidelines for the measurement deemed the most reliable estimator of splenic size.

RESULTS

Radiographic measurements of total and segmental splenic length were significantly correlated with the respective CT measurements and with splenic volume. Agreement between radiographic and CT measurements of segmental length was good; interobserver agreement was excellent for all variables. In retrospective evaluations, median segmental length of the spleen was 57.87 mm (range, 34.72 to 105.44 mm) on radiographs; the caudal border of the splenic head on lateral views was located from the cranial part of L1 to the caudal part of L2, and the caudal border of the splenic tail on ventrodorsal views was located from the caudal part of L2 to the caudal part of L5.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that segmental length of the spleen on radiographs is a reliable estimator of splenic size in healthy cats.

Restricted access
in American Journal of Veterinary Research