Colorectal Cancer Case Study 01


Clinical History
A 70-year-old male with a history of colorectal cancer had undergone surgery, chemotherapy and radiation therapy. The patient had rising CEA levels and a recent CT scan showed equivocal presacral soft tissue that has been stable for over a year.

Imaging Findings
NUCLEAR MEDICINE PET/CT
STATED REASON FOR REQUEST: Restaging colorectal cancer
TECHNIQUE: Emission and transmission scanning from the neck through the pelvis was obtained approximately one hour post-injection. Images were reconstructed with and without attenuation correction.
BLOOD GLUCOSE: 175 mg/dL.

PET/CT FINDINGS: The PET/CT scan revealed a focal area of intense increased uptake of radiopharmaceutical in the presacral space corresponding to small presacral node or soft tissue mass in that area on the CT portion of the exam. This area of increased uptake was very suspicious for recurrent malignancy.

Pathology Report
The initial CT guided biopsy of the presacral mass was negative. A repeat CT guided biopsy was positive for malignant cells, and confirmed moderately differentiated adenocarcinoma, consistent with metastasis from colonic primary.

Treatment and Follow-up
The patient underwent chemotherapy followed by resection of presacral mass.

Discussion
This patient was referred for PET/CT because of an elevated CEA level and equivocal CT finding. A recent CT scan showed a presacral area of soft tissue that had been stable for over a year and was thought to represent post treatment changes. Because his CEA level started to rise, a CT guided biopsy was performed which was negative. The patient then came for PET/CT. By looking at the PET portion of the exam, it was clear there was an abnormality and it appeared that it correlated with that presacral soft tissue. After inspecting the fused image, it was clear why the first biopsy might have been negative. Although it could not be determined for sure that there wasn't microscopic disease throughout the presacral mass, it appeared that only a focal area within the mass was metabolically active. In retrospect, there was a very subtle difference in attenuation, but this was not picked up prospectively.

This patient subsequently was sent for a CT-guided biopsy directed at the focal area of hypermetabolism. Fused images were printed and the radiologist took four samples with his needle as close to the metabolic abnormality as possible, which finally yielded the diagnosis of recurrent adenocarcinoma of the colon.

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

* Any of the protocols presented herein are for informational purposes and are not meant to substitute for clinician judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education, learning and experience.