title: Does focal incidental 18F-FDG PET/CT uptake in the prostate have significance?
abstract: OBJECTIVE
  (18)F-FDG PET/CT is used to characterize many malignancies, but is not recommended for localized prostate cancer. This study explores the value of multi-parametric MRI (mpMRI) in characterizing incidental prostate (18)F-FDG uptake.
  
  
  METHODS
  Thirty-one patients who underwent (18)F-FDG PET/CT for reasons unrelated to prostate cancer and prostate mpMRI were eligible for this retrospective study. The mpMRI included T2-weighted (T2W), dynamic contrast enhancement (DCE), apparent diffusion coefficient (ADC), and MR spectroscopy (MRS) sequences. Fourteen patients were excluded (n = 8 insufficient histopathology, n = 6 radical prostatectomy before PET), and final analysis included 17 patients. A nuclear medicine physician, blinded to clinicopathologic findings, identified suspicious areas and maximum standardized uptake values (SUV max) on (18)F-FDG PET/CT. Sector-based imaging findings were correlated with annotated histopathology from whole-mount or MRI/transrectal ultrasound fusion biopsy samples. Positive predictive values (PPVs) were estimated using generalized estimating equations with logit link. Results were evaluated with Kruskal-Wallis and Dunn's multiple comparisons tests.
  
  
  RESULTS
  The PPV of (18)F-FDG PET alone in detecting prostate cancer was 0.65. Combining (18)F-FDG PET as a base parameter with mpMRI (T2W, DCE, ADC, and MRS) increased the PPV to 0.82, 0.83, 0.83, and 0.94, respectively. All benign lesions had SUV max < 6. Malignant lesions had higher SUV max values that correlated with Gleason scores. There was a significant difference in SUV max per prostate between the Gleason ≥ 4 + 5 and benign categories (p = 0.03).
  
  
  CONCLUSIONS
  Focal incidental prostate (18)F-FDG uptake has low clinical utility alone, but regions of uptake may harbor high-grade prostate cancer, especially if SUV max > 6. Using mpMRI to further evaluate incidental (18)F-FDG uptake aids the diagnosis of prostate cancer.
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.|Duke University School of Medicine, Durham, NC, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Brown
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Lindenberg
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Sankineni
authors.affiliation: Biometric Research Branch, Division of Cancer Treatment and Diagnosis, NCI, NIH, Bethesda, MD, USA.
authors.forename: Joanna H
authors.initials: JH
authors.lastname: Shih
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Johnson
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Suneha
authors.initials: S
authors.lastname: Pruthy
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Kurdziel
authors.affiliation: Laboratory of Pathology, NCI, NIH, Bethesda, MD, USA.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Merino
authors.affiliation: Center for Interventional Oncology, NCI, NIH, Bethesda, MD, USA.|Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA.
authors.forename: Bradford J
authors.initials: BJ
authors.lastname: Wood
authors.affiliation: Urologic Oncology Branch, NCI, NIH, Bethesda, MD, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Pinto
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA.
authors.forename: Peter L
authors.initials: PL
authors.lastname: Choyke
authors.affiliation: Molecular Imaging Program, National Cancer Institute, NIH, 10 Center Drive, Room B3B85, Bethesda, MD, 20892, USA. turkbeyi@mail.nih.gov.
authors.forename: Baris
authors.initials: B
authors.lastname: Turkbey
mesh_terms: D000368:Aged; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011467:Prostate / Q000473:pathology; D011471:Prostatic Neoplasms / Q000473:pathology*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG PET; Incidental FDG uptake; Multi-parametric MRI; Prostate cancer