Page 135 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

114 PART II Diagnostic Procedures for the Cancer Patient

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• Fig. 6.1 A right lateral radiograph of the thorax (A) shows a pulmonary nodule in the ventral aspect of the
second intercostal space (arrow). Transverse CT image of the thorax at the same level (B) showed no evi-
dence of the nodule, indicating this was a summation artifact on the radiograph resulting in a false-positive
test for pulmonary metastasis.

• Fig. 6.2 Orthogonal radiographs of the stifle demonstrate an aggressive bone lesion in the proximal tibia
that is characterized by moth-eaten bone lysis and cortical loss. The primary modality for the initial assess-
ment of bone tumors remains radiography.

normal sonographic appearance does not necessarily exclude the wall layering is strongly predicative of neoplasia compared with
presence of disease. 2,19 This limitation is overcome by the use of nonfungal inflammatory diseases. 15,22 Connecting peritoneal
ultrasound-guided sampling techniques. Abdominal ultrasonog- masses may be indicative of carcinomatosis in cats (Fig. 6.4).
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raphy is also useful for the detection of comorbidities that may Hypoechoic subcapsular thickening of the kidneys is associated
have an effect on treatment options for cancer patients. 2,19,20 with renal lymphoma in cats. Ultrasound can also increase the
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Although ultrasound findings are generally not specific, there suspicion of multiple organ involvement or detect intraabdomi-
are patterns that may be more indicative of neoplasia. Target nal metastases. This information will help guide sampling recom-
lesions and focal nodules with a hyperechoic central region and mendations and may affect differential diagnoses and treatment
hypoechoic rim have been associated with a higher predictive decisions.
value for malignant neoplasia (Fig. 6.3). The positive-predictive Color Doppler can be used to assess vascular invasion and the
value for malignancy is 74% when a single nodule is identified in vascularity of masses (Fig. 6.5). Color Doppler displays the mean
either liver or spleen, and 81% when multiple target lesions are flow velocity and directional information using a color map, and
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identified in one organ. However, owing to the small sample this allows for visualization of smaller blood vessels and overall
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size in this study, positive-predictive values may be overestimated. vascular pattern and distribution. Spectral Doppler is required
In dogs and cats with gastrointestinal disease, the loss of normal to determine maximum flow velocity, but this is more technically