title: Local recurrence of prostate cancer after radical prostatectomy is at risk to be missed in68Ga-PSMA-11-PET of PET/CT and PET/MRI: comparison with mpMRI integrated in simultaneous PET/MRI.
abstract: OBJECTIVE
  The positron emission tomography (PET) tracer68Ga-PSMA-11, targeting the prostate-specific membrane antigen (PSMA), is rapidly excreted into the urinary tract. This leads to significant radioactivity in the bladder, which may limit the PET-detection of local recurrence (LR) of prostate cancer (PC) after radical prostatectomy (RP), developing in close proximity to the bladder. Here, we analyze if there is additional value of multi-parametric magnetic resonance imaging (mpMRI) compared to the68Ga-PSMA-11-PET-component of PET/CT or PET/MRI to detect LR.
  
  
  METHODS
  One hundred and nineteen patients with biochemical recurrence after prior RP underwent both hybrid68Ga-PSMA-11-PET/CTlow-dose(1 h p.i.) and -PET/MRI (2-3 h p.i.) including a mpMRI protocol of the prostatic bed. The comparison of both methods was restricted to the abdomen with focus on LR (McNemar). Bladder-LR distance and recurrence size were measured in axial T2w-TSE. A logistic regression was performed to determine the influence of these variables on detectability in68Ga-PSMA-11-PET. Standardized-uptake-value (SUVmean) quantification of LR was performed.
  
  
  RESULTS
  There were 93/119 patients that had at least one pathologic finding. In addition, 18/119 Patients (15.1%) were diagnosed with a LR in mpMRI of PET/MRI but only nine were PET-positive in PET/CT and PET/MRI. This mismatch was statistically significant (p = 0.004). Detection of LR using the PET-component was significantly influenced by proximity to the bladder (p = 0.028). The PET-pattern of LR-uptake was classified into three types (1): separated from bladder; (2): fuses with bladder, and (3): obliterated by bladder). The size of LRs did not affect PET-detectability (p = 0.84), mean size was 1.7 ± 0.69 cm long axis, 1.2 ± 0.46 cm short-axis. SUVmeanin nine men was 8.7 ± 3.7 (PET/CT) and 7.0 ± 4.2 (PET/MRI) but could not be quantified in the remaining nine cases (obliterated by bladder).
  
  
  CONCLUSIONS
  The present study demonstrates additional value of hybrid68Ga-PSMA-11-PET/MRI by gaining complementary diagnostic information compared tothe 68Ga-PSMA-11-PET/CTlow-dosefor patients with LR of PC.
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany. m.freitag@dkfz.de.|Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany. m.freitag@dkfz.de.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Freitag
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany.|Department of Urology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Jan P
authors.initials: JP
authors.lastname: Radtke
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: Afshar-Oromieh
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Matthias C
authors.initials: MC
authors.lastname: Roethke
authors.affiliation: Department of Urology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Boris A
authors.initials: BA
authors.lastname: Hadaschik
authors.affiliation: The Vancouver Prostate Centre, University of British Columbia, Vancouver, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Gleave
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Bonekamp
authors.affiliation: Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kopka
authors.affiliation: Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Eder
authors.affiliation: Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Heusser
authors.affiliation: Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Kachelriess
authors.affiliation: Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Wieczorek
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Christos
authors.initials: C
authors.lastname: Sachpekidis
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Flechsig
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Giesel
authors.affiliation: Department of Urology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Hohenfellner
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Haberkorn
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Dimitrakopoulou-Strauss
mesh_terms: D000368:Aged; D004492:Edetic Acid / Q000031:analogs & derivatives; D005188:False Negative Reactions; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D064847:Multimodal Imaging / Q000379:methods*; D009364:Neoplasm Recurrence, Local; D009842:Oligopeptides; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D012306:Risk
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
keywords: 68Ga-PSMA-11; Local recurrence; Local relapse; PET/CT; PET/MRI; Prostate specific membrane antigen