title: Reliability of a radiological grading system for dermal backflow in lymphoscintigraphy imaging.
abstract: OBJECTIVE
  Lymphoscintigraphy may be used for diagnosing secondary lymphedema. Dermal backflow, the presence of radiotracer in dermal lymphatics, is a key clinical feature. Although often reported as present or absent, a scale that assesses the severity of dermal backflow has been previously developed. The aim of this study was to determine the reliability of these two methods of assessment.
  
  
  METHODS
  Sixteen experienced nuclear medicine physicians assessed the quantity of dermal backflow of 57 lymphoscintigraphy scans using a 4-point descriptive scale that was dichotomized for secondary analysis. Each scan included images from four time points for women previously diagnosed with secondary lymphedema (n = 47) and controls (n = 5); five scans were presented twice to examine intraobserver reliability. This was further investigated as 13 physicians viewed the scans again on an Apple iPad2. The physicians rated their confidence in their scoring. Readers were blinded to clinical history.
  
  
  RESULTS
  Although both the 2- and 4-point scale had moderate interobserver reliability, the reliability of the 2-point scale was slightly higher (4-point: Fleiss κ = .418, standard error [SE] = .008); 2-point: Fleiss κ = .574, SE = .013). Low interobserver reliability was found when only control subjects were considered (Fleiss κ = 0.055, SE = 0.034). Intraobserver reliability of the five repeated images varied from poor to perfect (Cohen κ = .063 to 1.00), whereas moderate to substantial intraobserver reliability (Cohen's κ = .342 to .752) was found when comparing devices. The readers were highly confident of their scores.
  
  
  CONCLUSIONS
  Overall, moderate intraobserver and interobserver reliability was found for quantifying dermal backflow with both the 2- and 4-point scale.
authors.affiliation: Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe, New South Wales, Australia.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Dylke
authors.forename: Mark F
authors.initials: MF
authors.lastname: McEntee
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Schembri
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Brennan
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Bailey
authors.forename: Leigh C
authors.initials: LC
authors.lastname: Ward
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Kilbreath
mesh_terms: D016477:Artifacts; D001315:Australia; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000000981:diagnostic imaging* / Q000209:etiology*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D061305:Lymphoscintigraphy / Q000009:adverse effects* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011361:Professional Competence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000000981:diagnostic imaging*