PMC5106537_01
Patient with history of thyroid medullary carcinoma. A, Unenhanced CT of abdomen. Note the attenuation value of the cisterna chyli, 16.8 HU, is within the normal range for fluid. The cisterna chyli appears adjacent and to the right of the abdominal aorta, posterior to the right crus of the diaphragm. Cisterna chyli = 1 Abdominal aorta = 2. Subcutaneous fat = 3. B, PET-CT of cisterna chyli shows an SUVmax of 1.48. Relatively low metabolic activity suggests that the cylindrical structure is not a malignant recurrence.
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PET-CT, this structure was found to have an SUV max of 1.48, consistent with low metabolic activity. PET-CT, therefore, shows it to be physiologically inactive in comparison to the areas of tumor recurrence. (Figure 1).
PMC5106537_02
Patient with a history of esophageal carcinoma. A,Non-enhanced CT of abdomen. Note the cisterna chyli (1), whose mean attenuation value of 10.4 HU is within the normal range for fluid. Cisterna chyli = 1 Abdominal aorta = 2. Subcutaneous fat = 3. B, PET-CT of cisterna chyli shows an SUVmax of 1.35. Low metabolic activity is suggestive of a non-malignant structure.
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T12 with an SUV max of 1.35 on PET, likely a cisterna chyli. The structure appears tubular with attenuation similar to the adjacent non-enhanced abdominal aorta. (Figure 2). Thus, PET-CT was able to confirm that the suspicious structure on CT was most likely benign, rather than a suspicious enlarged retrocural lymph node.