Page 320 - Feline diagnostic imaging

326 20 Thorax
can be performed with the patient in sternal or lateral 20.2.2 Sampling Pulmonary Lesions
recumbency; positioning should accommodate any respir- Pulmonary lesions (nodules, masses, areas of infiltrate)
atory distress. Many patients tolerate prolonged thoraco-
centesis well in sternal recumbency. The selection of may be aspirated or biopsied if located sufficiently peripher-
ally for a good acoustic window [7,8]. The needle should be
window for fluid removal is based on the location of the
largest volume of fluid, and away from the heart, dia- placed within the more solid tissue of the lesion, avoiding
areas of air‐filled lung (Figures 20.3 and 20.4). Core biopsies
phragm, liver, or large vessels. Larger gauge needles (18–20 G)
are more efficient for rapid fluid removal, and an extension should not be performed unless there is sufficient solid lung
tissue for safe sampling. Cytologic results are often suffi-
set with stopcock allows continuous fluid evacuation with
minimal equipment disruption. Large amounts of fibrin cient for diagnosis of neoplastic disease, but may need to be
followed by biopsy if nondiagnostic [7]. Some tumors (mes-
can obstruct the needle, and necessitate finding a new
thoracocentesis window. enchymal tumors, for example) do not exfoliate well, or

(b)

(a)

(c)

Figure 20.3 Lateral (a) and ventrodorsal (b) thoracic images of a dog presented for coughing. A large soft tissue mass is noted in the
right caudal lung lobe. (c) Longitudinal ultrasound image of the right caudal lung lobe mass from the same dog. A needle (arrows)
enters the superficial aspect of the mass. Cytologic diagnosis was pulmonary carcinoma.