title: The reconstruction algorithm used for [68Ga]PSMA-HBED-CC PET/CT reconstruction significantly influences the number of detected lymph node metastases and coeliac ganglia.
abstract: OBJECTIVE
  To investigate whether the numbers of lymph node metastases and coeliac ganglia delineated on [68Ga]PSMA-HBED-CC PET/CT scans differ among datasets generated using different reconstruction algorithms.
  
  
  METHODS
  Data were constructed using the BLOB-OS-TF, BLOB-OS and 3D-RAMLA algorithms. All reconstructions were assessed by two nuclear medicine physicians for the number of pelvic/paraaortal lymph node metastases as well the number of coeliac ganglia. Standardized uptake values (SUV) were also calculated in different regions.
  
  
  RESULTS
  At least one [68Ga]PSMA-HBED-CC PET/CT-positive pelvic or paraaortal lymph node metastasis was found in 49 and 35 patients using the BLOB-OS-TF algorithm, in 42 and 33 patients using the BLOB-OS algorithm, and in 41 and 31 patients using the 3D-RAMLA algorithm, respectively, and a positive ganglion was found in 92, 59 and 24 of 100 patients using the three algorithms, respectively. Quantitatively, the SUVmean and SUVmax were significantly higher with the BLOB-OS algorithm than with either the BLOB-OS-TF or the 3D-RAMLA algorithm in all measured regions (p < 0.001 for all comparisons). The differences between the SUVs with the BLOB-OS-TF- and 3D-RAMLA algorithms were not significant in the aorta (SUVmean, p = 0.93; SUVmax, p = 0.97) but were significant in all other regions (p < 0.001 in all cases). The SUVmean ganglion/gluteus ratio was significantly higher with the BLOB-OS-TF algorithm than with either the BLOB-OS or the 3D-RAMLA algorithm and was significantly higher with the BLOB-OS than with the 3D-RAMLA algorithm (p < 0.001 in all cases).
  
  
  CONCLUSIONS
  The results of [68Ga]PSMA-HBED-CC PET/CT are affected by the reconstruction algorithm used. The highest number of lesions and physiological structures will be visualized using a modern algorithm employing time-of-flight information.
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany. thomas.krohn@uniklinik-ulm.de.|Department of Nuclear Medicine, Ulm University, Albert-Einstein-Allee 23, 89081, Ulm, Germany. thomas.krohn@uniklinik-ulm.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Krohn
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Anita
authors.initials: A
authors.lastname: Birmes
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Winz
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Natascha I
authors.initials: NI
authors.lastname: Drude
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.|Department of Nuclear Medicine, Maastricht UMC+, Maastricht, The Netherlands.
authors.forename: Felix M
authors.initials: FM
authors.lastname: Mottaghy
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.|Radiology Institute "Aachen Land", Würselen, Germany.
authors.forename: Florian F
authors.initials: FF
authors.lastname: Behrendt
authors.affiliation: Department of Nuclear Medicine, RWTH University Hospital Aachen, Aachen, Germany.|Department of Nuclear Medicine, University Hospital Giessen and Marburg, Marburg, Germany.
authors.forename: Frederik A
authors.initials: FA
authors.lastname: Verburg
mesh_terms: D000368:Aged; D000465:Algorithms; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D005728:Ganglia, Sympathetic / Q000000981:diagnostic imaging*; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods* / Q000592:standards; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D019275:Radiopharmaceuticals
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
keywords: PSMA PET/CT; PSMA-HBED-CC; Prostate cancer; Reconstruction algorithm; Staging