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Bladder diverticulum simulating a pelvic metastasis on a Tc-99m HDP bone scan
K D Farmer1, L R Gellett, G C Vivian
1Department of Radiology, Derriford Hospital, Plymouth, Devon, United Kingdom. kimfarmer8@hotmail.com
Clinical Nuclear Medicine
|January 4, 2001
Summary
A bone scan for prostate cancer staging revealed a false positive due to a bladder diverticulum retaining radioactive tracer. This highlights the importance of correlating imaging findings with anatomical structures for accurate diagnosis.
Area of Science:
- Nuclear medicine imaging
- Urologic oncology
- Radiology
Background:
- Prostate carcinoma diagnosis and staging are crucial for treatment planning.
- Bone scintigraphy using Technetium-99m hydroxymethylene diphosphonate (Tc-99m HDP) is a standard imaging modality for detecting bone metastases.
- Interpreting bone scan findings requires careful consideration of potential artifacts and non-osseous uptake.
Observation:
- A 74-year-old man diagnosed with prostate carcinoma underwent Tc-99m HDP bone scan for staging.
- The bone scan demonstrated an area of increased tracer uptake over the left sacroiliac joint, initially concerning for metastatic disease.
- Radiographs were inconclusive, necessitating further investigation.
Findings:
- Computed tomography (CT) revealed a large diverticulum of the urinary bladder on the left side.
- The increased tracer uptake on the bone scan was attributed to Tc-99m HDP retained within this bladder diverticulum.
- This finding represents a false positive on bone scintigraphy.
Implications:
- Bladder diverticula can cause false-positive findings on bone scans due to tracer accumulation.
- Accurate interpretation of bone scintigraphy necessitates correlation with cross-sectional imaging like CT to identify anatomical variants and artifacts.
- Understanding potential sources of aberrant tracer uptake is essential for precise staging of prostate carcinoma and avoiding unnecessary interventions.