Page 179 - Feline diagnostic imaging

11.2 ­ormal Anatomy 181

Figure 11.4 Longitudinal ultrasound image of the caudal Figure 11.5 Longitudinal ultrasound image of the caudal
thorax. The heart is surrounded by pleural effusion (pl eff), thorax. Bilateral pleural effusion is present. The caudal
which appears more echogenic than noted in Figure 11.2. FIP mediastinal tissue is thickened and irregular (arrow). A lung lobe
was the final diagnosis. Cranial is to the left in this image. is small and triangular, consistent with atelectasis (*).
Carcinomatosis was the final diagnosis in this feline patient,
who had irregular thickening of most of the pleural surfaces, as
the liver. Pyothorax with a septic exudative fluid typically well as a primary lung mass. Cranial is to the right of the image.
results in echogenic effusion and is frequently unilateral.
Lung lobe abscesses and consolidation from pneumonia
may accompany the echogenic fluid [4,5]. Hemorrhage
and neoplastic effusions are also commonly echogenic
(Figure 11.4). Anechoic pleural fluid is more consistent
with transudates, modified transudates, and chylous effu-
sions. Chronic effusions may contain large numbers of
thin, mobile echogenic strands representing fibrin. Variable
lung lobe atelectasis is present, depending on the volume
of pleural effusion. Thickening and irregularity of the pleu-
ral surfaces may be seen with pyothorax, neoplastic effu-
sions, and the effusive form of feline infectious peritonitis
(FIP) (Figure 11.5). A thorough evaluation for the cause of
the pleural effusion should be performed, checking for
abnormalities of the chest wall, heart, pleura, and lung
lobes. Ultrasound is extremely useful for guiding thoraco-
centesis when pleural fluid is restricted to small pockets, Figure 11.6 Longitudinal ultrasound image of the cranial
thorax. Bilateral pleural effusion is present. A small, ovoid mass
and to help avoid vascular structures. (ms mass) is noted in the cranial mediastinum. The mass was
not visible on thoracic radiographs because of the small size
and pleural effusion. Lymphoma was diagnosed on a fine needle
11.2.2 Pneumothorax aspirate. Cranial is to the left of the image.
Pneumothorax is most commonly diagnosed radiographi-
cally, but can be detected on thoracic ultrasound. Pleural 11.2.3 Mediastinal Masses
air will create an echogenic interface, with reverberation Visualization of mediastinal masses depends on their size
artifact, that does not move with normal lung gliding and and location; they are usually best visualized from a par-
respiration. It can be difficult to differentiate reverberation asternal approach. The presence of pleural fluid is helpful
in air‐filled lung from reverberation from a pneumotho- to act as an acoustic window, but is not essential for visuali-
rax. However, ultrasound can be very sensitive for the zation of larger masses (Figure 11.6).
diagnosis of pneumothorax in the hands of an experienced Mediastinal masses are found most commonly in the
sonographer [6]. cranioventral mediastinum, and may appear as diffusely