Anatomic, computed tomographic, and ultrasonographic assessment of the lymph nodes in presumed healthy adult cats: The head, neck, thorax, and forelimb

Abstract

Assessment of the lymph nodes is key in staging cancer patients. Descriptions of normal features of the feline lymph nodes using computed tomography (CT) and ultrasound (US) are limited. A prospective anatomic and comparative imaging study was performed. The frequency of identification and the size of the lymph nodes during gross pathology from 6 feline cadavers were compared to the images of lymph nodes from 30 presumed healthy adult cats obtained by CT and US. Measurements (length, width, and height) were compared among techniques. The CT and US features of the identified lymph nodes were also recorded. The frequency of identification of the lymph centers varied among techniques and individually. The mandibular lymph nodes were identified in 100% of the cadavers and in 100% of the healthy cats using CT and US. The medial retropharyngeal lymph nodes were identified in 100% of the cats using CT and US. The deep cervical lymph nodes were not visualized in the cadavers. The cranial mediastinal and tracheobronchial lymph nodes were not visualized using US. Lymph nodes showed a higher length on CT and higher width on US. The height was the most statistically significant variable measurement among techniques. On CT, lymph nodes were most frequently isoattenuating or slightly hypoattenuating to surrounding musculature, with homogeneous contrast enhancement. On US, most lymph nodes were isoechoic or hypoechoic to surrounding fat tissue. The lymph nodes were most frequently elongated or rounded.

Anatomic, computed tomographic, and ultrasonographic assessment of the lymph nodes in presumed healthy adult cats: the abdomen, pelvis, and hindlimb

“…In our study, some of the lymph nodes in the abdominal cavity (splenic and renal) and in the hindlimb (popliteal) showed a nodal periphery isoattenuating or slightly hypoattenuating to the musculature; meanwhile, the center of the node was hypoattenuating. This appearance has been reported for abdominal lymph nodes in dogs [2,15,19], and has been observed by these authors for the sternal and axillary lymph nodes in healthy cats, and is produced by the presence of a fatty hilus [11]. After contrast administration, a homogeneous contrast enhancement was more frequently visualized.…”

“…Clinically healthy status was determined based on physical examination (performed by AA and XM), biochemical profile [glucose, total proteins, cholesterol, calcium, potassium, alanine-amino-transferase (ALT), gamma-glutamyl-transferase (GGT), creatinine, urea], complete blood count, fast test to rule out feline immunodeficiency virus antibodies and feline leukemia virus antigens, and a polymerase chain reaction test for Bartonella sp. as described previously by the authors [ 11 ]. To perform CT and US, the patients underwent sedation using midazolam (0.2 mg/kg) (Midazolam 15 mg/3 mL, Normon, Spain), butorphanol (0.4 mg/kg) (Torbugesic 10 mg/mL, Zoetis, Madrid, Spain), and ketamine (5 mg/kg) (Imalgene 100 mg/mL, Merial, Barcelona, Spain).…”

“…Technical details were: slice thickness of 0.625 mm, interval thickness of 0.625 mm, collimation pitch of 1.25 mm, 120 kV, 50–90 mA, and matrix of 512 × 512. In this study, the assessment of the abdominal cavity to identify the lymph nodes was performed following anatomic references and available literature [ 3 , 4 , 11 , 16 ]. Using multiplanar reconstruction on CT images, the lymph nodes along the intestinal tract (e.g., colic lymph node) or along the great vessels of the abdomen (e.g., medial iliac lymph node) were numbered from oral to aboral and from cranial to caudal, respectively.…”

“…The CT dimensions and features of each identified lymph node were performed following previously described methods for measuring and comparing CT images [ 2 , 9 , 11 ]. All recollected data were recorded using an image archiving and communication system software (Centricity PACS-IW, General Electric ® Healthcare).…”

Veterinary forensic radiology–Development of a cost-effective and easily performed post mortem computed tomographic angiography protocol

“…27 In veterinary radiology, especially in feline radiology (where cats have a more uniform body size) there are established CT references for each lymph node size. [28][29][30][31] This allows for increased identification of subtly or mildly enlarged lymph nodes that could be overlooked on necropsy. In most cases, the pathologists were not made aware of all enlarged lymph nodes on the preliminary PMCTA findings.…”