Recurrent prostate cancer detection with anti-3-[(18)F]FACBC PET/CT: comparison with CT

Abstract

Purpose: To compare the diagnostic performance of the synthetic amino acid analogue PET radiotracer anti-3-[(18)F]FACBC (fluciclovine) with that of CT in the detection of recurrent prostate carcinoma.

Methods: This was a retrospective analysis of 53 bone scan-negative patients with suspected recurrent prostate carcinoma who underwent fluciclovine PET/CT and routine clinical CT within 90 days of each other. The correlation between imaging findings and histology and clinical follow-up was evaluated. Positivity rates and diagnostic performance were calculated for fluciclovine PET/CT and CT.

Results: Of 53 fluciclovine PET/CT and 53 CT examinations, 41 (77.4 %) and 10 (18.9 %), respectively, had positive findings for recurrent disease. Positivity rates were higher with fluciclovine PET/CT than with CT at all prostate-specific antigen (PSA) levels, PSA doubling times and original Gleason scores. In the prostate/bed, fluciclovine PET/CT was true-positive in 31 and CT was true-positive in 4 of 51 patients who met the reference standard. In extraprostatic regions, fluciclovine PET/CT was true-positive in 12 and CT was true-positive in 3 of 41 patients who met the reference standard. Of the 43 index lesions used to prove positivity, 42 (97.7 %) had histological proof. In 51 patients with sufficient follow-up to calculate diagnostic performance in the prostate/bed, fluciclovine PET/CT demonstrated a sensitivity of 88.6 %, a specificity of 56.3 %, an accuracy of 78.4 %, a positive predictive value (PPV) of 81.6 %, and a negative predictive value (NPV) of 69.2 %; the respective values for CT were 11.4 %, 87.5 %, 35.3 %, 66.7 % and 31.1 %. In 41 patients with sufficient follow-up to calculate diagnostic performance in extraprostatic regions, fluciclovine PET/CT demonstrated a sensitivity of 46.2 %, a specificity of 100 %, an accuracy of 65.9 %, a PPV of 100 %, and an NPV of 51.7 %; the respective values for CT were 11.5 %, 100 %, 43.9 %, 100 % and 39.5 %.

Conclusion: The diagnostic performance of fluciclovine PET/CT in recurrent prostate cancer is superior to that of CT and fluciclovine PET/CT provides better delineation of prostatic from extraprostatic recurrence.

Keywords: CT; Diagnostic performance; FACBC; Fluciclovine; PET; Prostate cancer.

Fig. 1

Diagram of fluciclovine PET-CT and CT scan results with comparison to reference standard in both prostate/bed and extraprostatic regions.

Fig. 2

Whole body positivity rates in fluciclovine PET-CT and CT scans in relation to PSA (A), PSA doubling time (B) and Gleason Score (C).

Fig. 3. True positive fluciclovine PET-CT and false negative CT in the prostate

66 year old patient who had external beam radiation therapy and brachytherapy for prostate cancer with subsequent rise in PSA to 4.85ng/ml. Prostate was positive on biopsy (not shown). Co-registered fluciclovine PET-CT (A) shows abnormal uptake in the prostate meeting criteria for positivity (yellow arrow). CT scan (B) was negative in the prostate.

Fig. 4. True positive sub-centimetre lymph node on fluciclovine PET-CT and false negative on CT

72 year old patient had prostatectomy, external beam radiation therapy and hormone therapy for prostate cancer with subsequent rise in PSA to1.78 ng/ml. 0.4cm × 0.6cm left obturator lymph node (yellow arrow) was positive on coregistered fluciclovine PET-CT (A) but negative on CT (B). Cytology specimen (400X) of the lymph node biopsy (C) demonstrates metastatic prostatic adenocarcinoma.

Fig. 5. True positive lymph node on both fluciclovine PET-CT and CT

76 year old patient had external beam radiation therapy for prostate cancer with subsequent rise in PSA to 5.3ng/ml. Both co-registered fluciclovine PET-CT (A) and CT (B) were positive in a 1.0 cm round right obturator lymph node (yellow arrow). H&E stained section (100X) of the lymph node (C) demonstrates metastatic prostatic adenocarcinoma with extranodal extension.