Radiographic Detection of Intrathoracic Lymphadenomegaly in Dogs: How Useful Is It?

Area of Science:

• Veterinary Radiology
• Comparative Pathology
• Diagnostic Imaging

Background:

• Intrathoracic lymph nodes (LN) like sternal (STLN), cranial mediastinal (CrMLN), and tracheobronchial (TBLN) are key in canine diagnostics.
• While computed tomography (CT) offers precise LN measurement, thoracic radiography remains a common screening tool.

Purpose of the Study:

• To evaluate the consistency of radiographic identification of canine intrathoracic lymphadenomegaly.
• To compare radiographic assessments with CT-derived lymph node volumes.

Main Methods:

• A retrospective, multicenter study analyzed three-view thoracic radiographs from 74 dogs.
• Three board-certified radiologists independently graded STLN, CrMLN, and TBLN using a 5-point scale.
• CT volumes were calculated, and associations between radiographic grades and CT volumes were assessed using Spearman's rank correlation.

Main Results:

• High inter-observer agreement was observed for radiographic grading (AC1 scores > 0.88).
• Correlations between radiographic grades and CT volumes were weak or nonsignificant.
• Radiographs frequently under- or over-detected lymph node enlargement compared to CT volumes.

Conclusions:

• Despite high observer agreement, radiographic assessment of canine intrathoracic lymphadenomegaly shows poor alignment with CT-measured volumes.
• CT imaging is crucial for accurate intrathoracic lymph node assessment influencing clinical decision-making.