Validation of ultrasonographic muscle thickness measurements as compared to the gold standard of computed tomography in dogs.
OBJECTIVE
The objective was to quantitatively evaluate the validity of ultrasonographic (US) muscle measurements as compared to the gold standard of computed tomography (CT) in the canine.


METHODS
This was a prospective study.


METHODS
Twenty-five, client-owned dogs scheduled for CT as part of a diagnostic work-up for the management of their primary disease process were included.


METHODS
Specific appendicular (cubital flexors and extensors, coxofemoral flexors and extensors) and axial (temporalis, supraspinatus, infraspinatus, lumbar epaxials) muscle groups were selected for quantitative measure based on CT planning and patient position. Prior to CT scan, the skin over the muscle sites was shaved and marked with a permanent marker. Patient body position was determined based on the patient's CT plan; positioning was consistent between CT and US imaging. To ensure identical imaging position for both CT and US measurements, radio-opaque fiducial markers were placed directly over the skin marks once the dog was positioned. Quantitative measurements (cm) for both lean muscle mass (LMM) and subcutaneous adipose (SQA) were recorded. Statistical comparisons between CT and US values were done separately for each site and type.


RESULTS
Muscle groups and associated SQA measured by US and CT were not statistically different based on an adjustedp-value using Bonferroni's correction (p< 0.0031). In addition, all LMM and SQA sites had good reliability and agreement (Cronbach'sα= 0.8 - 1.0) between the two metrics, excluding the coxofemoral extensor muscle group (Cronbach'sα= 0.73232). Linear regression analysis of muscle measures indicated close agreement (slope range 0.93-1.09) and minimal bias of variation (intercept range 0.05-0.11) between CT versus US modalities, with the exception of the coxofemoral extensor muscle. Similarly, SQA CT and US measures indicated close agreement with the slope range of 0.88-1.02 and minimal bias of variation with an intercept range of 0.021-0.098, excluding the cubital flexor and extensor groups. Additionally, theR2values for these remaining LMM and SQA sites are reported as >0.897 for LLM and >0.8289 for SQA.


CONCLUSIONS
Ultrasound imaging of selected appendicular and axial muscle groups in dogs can provide comparable assessment of muscle thickness to the current gold standard, CT. In consideration of both statistical reliability to CT and cage-side accessibility, thetemporalis, supraspinatus, infraspinatus,andlumbar epaxialLMM sites are considered the most useful targets for US LMM assessment in the canine. Our findings support the potential utility of US as a clinical tool in veterinary medicine to assess LMM status in patients. Additional studies are indicated to develop standardized protocols of its use in a cage-side setting and to elucidate the benefit of this modality, in conjunction with nutritional interventions, to manage body LLM stores in compromised patients.
College of Veterinary Medicine: Department of Molecular Biomedical Sciences, North Carolina State University , Raleigh , NC , United States.
Lindsey E
LE
Bullen
College of Veterinary Medicine: Department of Molecular Biomedical Sciences, North Carolina State University , Raleigh , NC , United States.
Maria G
MG
Evola
College of Sciences: Department of Statistics, North Carolina State University , Raleigh , NC , United States.
Emily H
EH
Griffith
College of Veterinary Medicine: Department of Molecular Biomedical Sciences, North Carolina State University , Raleigh , NC , United States.
Gabriela S
GS
Seiler
College of Veterinary Medicine: Department of Molecular Biomedical Sciences, North Carolina State University , Raleigh , NC , United States.
Korinn E
KE
Saker
Canine; Computed tomography; DEXA; Dog; Monitoring; Muscle loss; Muscle thickness; Nutrition; Ultrasound; Veterinary