Esophageal Cancer - A 69 year old man with a history of esophageal cancer

Clinical History
A 69 year old man with a history of esophageal cancer and esophagectomy was referred for a 6 month follow-up PET•CT scan.

Imaging Technique
Emission scanning from the neck through the pelvis was obtained approximately one hour post-injection of 10.38 mCi of F18 FDG IV. Images were reconstructed with and without attenuation correction using the CT attenuation coefficients from the corresponding CT portion of the exam. The patient's blood glucose measured 76 mg/dl.

Imaging Findings
A single calcified mediastinal lymph node, with apparent FDG uptake was visualized on the attenuation-corrected images. However, this uptake was not present on the emission images and represented an attenuation correction artifact due to dense calcium within the node. There was no evidence of malignancy.

Discussion
This case is important for referring physicians to be familiar with because it is one of the clinically relevant attenuation correction artifacts in PEToCT imaging. It is important for every referring physician to be aware of this artifact because normally they are sent the attenuation corrected PET images to look at. These images are worrisome for a malignant lymph node; however, when a large calcified node is present, an artifact should always be a consideration. The way to prove whether something is an artifact from attenuation correction, is to look at the uncorrected emission images, which show no evidence for uptake in this area.

Data courtesy of Dr. Todd Blodgett, University of Pittsburgh Medical Center