Diagnostic accuracy of contrast‐enhanced computed tomography for assessment of mandibular and medial retropharyngeal lymph node metastasis in dogs with oral and nasal cancer

Abstract

The diagnostic accuracy of contrast-enhanced CT for detection of cervical lymph node metastasis in dogs is unknown. The purpose of this retrospective, observational, diagnostic accuracy study was to assess the efficacy of CT for detection of mandibular and medial retropharyngeal lymph node metastasis in dogs. Histopathology of dogs with cancer of the head, CT and bilateral mandibular and medial retropharyngeal lymphadenectomy was reviewed. A single radiologist measured lymph nodes to derive short axis width and long-short axis ratios. Two blinded radiologists separately assessed lymph node margins, attenuation and contrast enhancement and each provided a final subjective interpretation of each node site as benign or neoplastic. Where radiologists' opinions differed, a consensus was reached. Sensitivity, specificity and accuracy were calculated for mandibular and medial retropharyngeal sites. Agreement between radiologists was assessed. Fisher's exact test and the Kruskal-Wallis H-test were used to assess associations between variables. Forty-one primary tumours were recorded in 40 dogs. Metastasis to mandibular or retropharyngeal lymph nodes occurred in 16 out of 40 dogs (43/160 nodes). Agreement between radiologists was almost perfect for margination, attenuation and enhancement, strong for interpretation of mandibular lymph node metastasis, and weak for interpretation of medial retropharyngeal lymph node metastasis. Sensitivity of CT was 12.5% and 10.5%, specificity was 91.1% and 96.7%, and accuracy was 67.5% and 76.3% for mandibular and medial retropharyngeal lymph nodes respectively. No individual CT findings were predictive of nodal metastasis. Given the low sensitivity of CT, this modality cannot be relied upon alone for assessment of cervical lymph node metastasis in dogs.

Pilot study to evaluate the efficacy of lymphotropic nanoparticle enhanced MRI for diagnosis of metastatic disease in canine head and neck tumours

“…In addition, calculation of PSIL was significantly different between metastatic and non‐metastatic lymph nodes, showing that subjective assessment and quantitative analysis was reflective of histological results in this small population of dogs. This is in contrast to multiple other studies in dogs with head and neck tumours where more recent articles have indicated a lower level of sensitivity and specificity of imaging parameters such as apparent diffusion coefficient (ADC) values, contrast enhancement patterns and size for predicting presence of metastasis …”

“…In one article regarding staging for oral melanomas in dogs, there was a reported sensitivity and specificity of 70% and 51%, respectively, for diagnosis of lymph node metastasis based on the size of the lymph node alone . Imaging characteristics of lymph nodes on CT for canine oral and nasal tumours have shown to have a sensitivity and specificity of 12.5% and 91.1% for the diagnosis of metastasis in another report . Non‐invasive methods of identifying lymph node metastasis is an on‐going area of research that continues to attract considerable attention …”

“…Imaging characteristics of lymph nodes on CT for canine oral and nasal tumours have shown to have a sensitivity and specificity of 12.5% and 91.1% for the diagnosis of metastasis in another report . Non‐invasive methods of identifying lymph node metastasis is an on‐going area of research that continues to attract considerable attention …”

Significant advances in veterinary oncology – 60 years on

“…CT is more sensitive than radiography for detecting pulmonary nodules and is becoming the imaging method of choice for assessment of pulmonary metastasis, especially for highly malignant tumours such as osteosarcoma and melanoma (Armbrust et al 2012); in oral malignant melanoma, CT can also be used to assess mandibular and retropharyngeal lymphadenopathy. However, even with contrast enhancement, the sensitivity of CT in detection of cervical lymph node metastasis is low and CT cannot be relied on alone for this purpose (Skinner et al 2018). On the other hand, CT is more sensitive than radiography for detection of mediastinal lymphadenopathy and would be the method of choice for assessment of an animal with a lung mass.…”

“…However, even with contrast enhancement, the sensitivity of CT in detection of cervical lymph node metastasis is low and CT cannot be relied on alone for this purpose (Skinner et al . ). On the other hand, CT is more sensitive than radiography for detection of mediastinal lymphadenopathy and would be the method of choice for assessment of an animal with a lung mass.…”