title: Performance of a SPECT collimator-detector response reconstruction algorithm: phantom studies and validation in inflammation clinical studies.
abstract: OBJECTIVE
  To evaluate evolution for bone (EfB), one of the recent corrective collimator detector response (CDR) image reconstruction packages, resolution recovery and iterative reconstruction protocols were compared to the standard Filtered Back Projection (FBP) protocol and the possibility of time reduced acquisition (15 instead of 30 seconds/projection) was evaluated.
  
  
  METHODS
  Tomographic spatial resolution, contrast, noise and signal-to-noise ratio (SNR) were analyzed in phantom studies. Patient studies were conducted on sixteen [99mTc]HMPAO labeled leukocyte patients with suspected local inflammation, submitted to SPECT/CT and conventional leukocyte scintigraphy. Target background ratio (TBR) and boundary of each lesion were calculated. Images were also analyzed by visual inspection by two blinded expert physicians.
  
  
  RESULTS
  a) Phantom: resolution in phantom improves with the use of EfB mainly due to iterative reconstruction methods vs FBP. EfB shows a reduction in noise. No differences were found in contrast data, while SNR changes were mainly due to changes in noise. Time reduction, while increasing image noise, does not modify resolution; nevertheless, half-time EfB noise is the same as full-time FBP noise. b)
  
  
  METHODS
  lesion boundary is better defined in patient studies using iterative reconstruction vs FBP; no changes were observed for CDR vs iterative OSEM, or for full-time vs half-time acquisition. TBR is comparable in iterative and FBP protocols, while it is improved by EfB. At visual inspection, a higher score is always associated with EfB.
  
  
  CONCLUSIONS
  Resolution, noise, SNR and TBR improve when applying the resolution recovery. EfB permits reduction of acquisition time without compromising image quality.
authors.affiliation: Nuclear Medicine Unit, San Gerardo Hospital of Monza, Monza, Italy. m.arosio@hsgerardo.org
authors.forename: M
authors.initials: M
authors.lastname: Arosio
authors.forename: C
authors.initials: C
authors.lastname: Pasquali
authors.forename: C
authors.initials: C
authors.lastname: Crivellaro
authors.forename: E
authors.initials: E
authors.lastname: De Ponti
authors.forename: S
authors.initials: S
authors.lastname: Morzenti
authors.forename: L
authors.initials: L
authors.lastname: Guerra
authors.forename: A
authors.initials: A
authors.lastname: Crespi
authors.forename: C
authors.initials: C
authors.lastname: Messa
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007553:Isotope Labeling; D007962:Leukocytes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010019:Osteomyelitis / Q000175:diagnosis*; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D013382:Subtraction Technique; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals