Distribution of alveolar-interstitial syndrome in dogs and cats with respiratory distress as assessed by lung ultrasound versus thoracic radiographs.

ObjectiveTo assess distribution of alveolar-interstitial syndrome (AIS) detected by lung ultrasound (LUS) compared to thoracic radiographs (TXR). DesignProspective study. SettingUniversity teaching hospital. AnimalsSeventy-six dogs and 24 cats with acute respiratory distress or tachypnea. InterventionsPatients underwent LUS and TXR within 6 hours. Lung ultrasound images were scored for presence and quantity of B-lines in 4 lung quadrants (right cranial, right caudal, left cranial, left caudal). An individual LUS quadrant was scored positive if > 3 B-lines were observed within a single intercostal space. Dorsoventral TXR were scored for presence of AIS in the same 4 quadrants. An individual TXR quadrant was scored positive if infiltrate was present in 25% of the quadrant. Medical records were evaluated for final diagnosis. Measurements and Main ResultsQuadrant-by-quadrant spatial agreement in assigning AIS using LUS versus TXR was fair (K=0.24 - 0.56). Lung ultrasound scored a higher number of quadrants positive per patient (2.651.59 vs. 2.13 +/- 1.48; P=0.012). Patterns of distribution of AIS differed significantly based on final diagnosis. Patients with left-sided congestive heart failure were more likely to have diffuse AIS on LUS (P<0.001) or bilateral caudal AIS on TXR (P=0.04) while patients with noncardiac disease were more likely to have absence of AIS in all quadrants using either modality (P<0.001). Differences in spatial distribution of AIS were also noted among disease subcategories. ConclusionsLung ultrasound and TXR were both useful to detect and categorize distribution of alveolar or interstitial pulmonary pathology. Spatial agreement between modalities was only fair. Overall, LUS detected a higher incidence of AIS compared to TXR. Both modalities detected differences in distribution of AIS based on final diagnosis, suggesting that a regional pattern-based approach to thoracic imaging may prove diagnostically useful.