Case Author(s): Scott Winner, M.D. and Farrokh Dehdashti M.D. , 11/01/96 . Rating: #D4, #Q3

Diagnosis: tortuous, ectatic ureter

Brief history:

63-year old man with a history of rectal adenocarcinoma

Images:

PET images progressing from anterior to posterior.

View main image(pt) in a separate image viewer

View second image(ct). CT of the pelvis without contrast

View third image(ct). CT of the pelvis with contrast

Full history/Diagnosis is available below

Diagnosis: tortuous, ectatic ureter

Full history:

The patient has a history of rectal adenocarcinoma, which was treated with preoperative radiotherapy. The patientıs carcinoma was resected on 9-9-95 with a tumor stage of T3, N0, M0. A CT scan done without contrast on 9-17-96 demonstrated a 1.2 cm right perirectal lymph node. The patient presented for further evaluation with positron emission tomography on 10-1-96.

Radiopharmaceutical:

14.7 mCi F-18 fluorodeoxyglucose

Findings:

There is a focus of intense FDG accumulation in the pelvis which corresponds in location with the right perirectal lymph node seen on the CT of 9-17- 96. This is suspicious for metastatic disease.

Discussion:

The non-contrast pelvic CT of 9-17-96 and the PET study of 10-1-96 were false-positive studies. Further evaluation with a contrast enhanced CT on 10-30-96 demonstrated that the suspected 1.2 cm right perirectal lymph node was in fact a slightly dilated tortuous right ureter. The activity seen at this location on the PET study represented normal FDG pooling within the ureter. FDG is cleared from the circulation by renal excretion (the mechanism of renal clearence of FDG is not well understood). Activity within the ureters and bladder is normally seen and can sometimes mimic pathology.

Followup:

None.

Major teaching point(s):

A careful correlation with cross-sectional imaging is essential to avoid misinterpretation of the PET images.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Genitourinary System, Category:Normal, Technique, Congenital Anomaly)

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Case number: pt013

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