title: A clinical comparison between traditional planar V/Q images and planar images generated from SPECT V/Q scintigraphy.
abstract: OBJECTIVE
  To compare interpretation of traditional planar ventilation-perfusion lung scan images with planar images reformatted from single photon emission computed tomography (SPECT) data using two different techniques.
  
  
  METHODS
  Planar and SPECT ventilation-perfusion (V/Q) data were acquired from 50 patients referred with suspected pulmonary embolism. In addition to traditional six-view planar images, six-view planar images were also generated from SPECT data using two methodologies: an angular summing technique (angular summed planar images) and a forward projection technique (reprojected planar images). Three experienced nuclear medicine clinicians reviewed the images in a blinded, randomized fashion. Results were analysed by comparing the two reprojected techniques with the traditional true planar scans, examining for differences in the defects seen (number, type and confidence), and the impact on final clinical interpretation.
  
  
  RESULTS
  Compared with true planar scintigraphy, angular summed images demonstrated fewer mismatched defects (P<0.0001), while the reprojected planar images had more matched defects (P=0.013). In addition, there was a significant change in the clinical interpretation of the angular summed planar images resulting in clinicians perceiving a decreased likelihood of pulmonary embolism (P<0.016). No such difference in interpretation was observed for the reprojected planar images.
  
  
  CONCLUSIONS
  Angular summed planar images result in a perceived decreased likelihood of pulmonary embolism compared with true planar images. In contrast, while reprojected planar images result in an increased number of matched defects compared to true planar scans, there was no change in the clinical interpretation. Caution should be exercised when interpreting SPECT derived angular summed planar images in isolation.
authors.affiliation: Department of Respiratory Medicine, Royal North Shore Hospital, St Leonards, Australia. bharris@med.usyd.edu.au
authors.forename: Benjamin
authors.initials: B
authors.lastname: Harris
authors.forename: Dale L
authors.initials: DL
authors.lastname: Bailey
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Roach
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Schembri
authors.forename: Ivan
authors.initials: I
authors.lastname: Hoshon
authors.forename: Peter
authors.initials: P
authors.lastname: Chicco
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Bailey
authors.forename: Gregory G
authors.initials: GG
authors.lastname: King
mesh_terms: D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*