Ultrasonography and noncontrast computed tomography of medial retropharyngeal lymph nodes in healthy cats

Nemanic S, Nelson NC.

American Journal of Veterinary Research 2012;73:1377-1385.

Objective-To determine various measurements of medial retropharyngeal lymph nodes (MRPLNs) in healthy cats via ultrasonography and CT. Animals-45 cats (age range, 2 to 8 years). Procedures-Cats underwent CT of the head and ultrasonography of the cervical region. Various measurements of MRPLNs were obtained, and parenchymal heterogeneity, presence of a hilus, appearance of margins, and attenuation of MRPLNs were determined. Results-Data for 7 cats were excluded because they did not meet inclusion criteria; data for 38 cats were evaluated. Measurements of left and right MRPLNs were not significantly different. Mean length x rostral height x rostral width dimensions of MRPLNs were 20.7 x 12.4 x 3.7 mm and 20.7 x 13.1 x 4.7 mm in ultrasonographic and CT images, respectively. Maximum MRPLN dimensions were approximately 32 x 20 x 7 mm. Mean attenuation of MRPLNs was 40.2 Hounsfield units. Parenchyma of MRPLNs was mildly (via CT) to moderately (via ultrasonography) heterogeneous. A hilus was identified in 95% (via ultrasonography) and 24% or 92% (via CT [depending on criteria used to define a hilus]) of MPRLNs. Lymph node margins were smooth in CT images and mildly irregular in ultrasonographic images. A negative linear correlation was detected between age of cat and MRPLN volume. Conclusions and Clinical Relevance-MRPLNs in cats were easily imaged via ultrasonography and CT. Left and right MRPLNs were symmetric, and MRPLNs were larger in young adult cats versus old cats. Data were intended to serve as references for evaluation of MRPLNs in healthy cats.