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Patients treated with hormonal therapy often experience disease progression, which manifests in the form of a rising PSA. Outside of bone scans, novel imaging techniques are being explored to expedite the detection of metastases for patients with newly diagnosed castration-resistant prostate cancer (CRPC).
Studies have shown that F18 FDG and sodium fluoride (NaF) PET/CT scans are significantly more sensitive than traditional approaches using technetium-99. These scans have been available for sometime but are not commonly used, despite their increased sensitivity, as a result of reimbursement concerns, believes Steven E. Finkelstein, MD.
Another highly sensitive imaging technique for men with biochemically recurrent prostate cancer employs C11-choline or C11-acetate. However, these approaches are highly technical and require specialized equipment, notes Finkelstein. As a result, C11-choline and -acetate scans remain largely inaccessible, due to the limited number of sites that can produce these agents.
Particularly given the shortage of technetium, F18 NaF is a reasonable substitution that appears to be more sensitive and specific, notes E. David Crawford, MD. In some cases, F18 NaF PET scans may be too sensitive and not adequately specific, causing false-positives compared with MRI, believes Crawford.
Following a baseline scan at the time of diagnosis with CRPC, the traditional approach for follow-up imaging is based largely on PSA doubling times, notes Vahan Kassabian, MD. Approximately 50% of patients develop metastatic disease within 2 years of progression. As a result, follow-up scans are usually conducted between 6 to 18 months following diagnosis.