Table 3:

Reader agreement of lower-dose reconstruction configurations compared with routine-dose unenhanced head CT examinations, along with JAFROC FOMsa

Lower-Dose–Reconstruction Configuration% of the 47 Essential Lesionsb Detected by Readers at Lower-Dose ConfigurationsNo. of Successful Interpretations per Lower- Dose–Reconstruction ConfigurationJAFROC FOM (95% CI)
2 of 33 of 3Cases with at Least 1 Essential Lesion (n = 34)Cases without Any Essential Lesions (n = 49)No. Successful Interpretations (≥71 Required per Design)
200 eff. mAs FBP44 (94%)39 (83%)3048780.846 (0.78–0.912)
100 eff. mAs IR43 (92%)37 (79%)2946750.831 (0.764–0.898)
100 eff. mAs FBP42 (89%)36 (77%)2845730.805 (0.732–0.878)
50 eff. mAs IR41 (87%)32 (68%)2647730.795 (0.727–0.864)
50 eff. mAs FBP38 (81%)31 (66%)2547720.789 (0.717–0.861)
25 eff. mAs IR34 (72%)25 (53%)224567c0.754 (0.681–0.827)
  • a The JAFROC FOM for routine unenhanced head CT (250 eff. mAs with IR) was 0.867 (0.805–0.929).

  • b Essential lesions are described in the Materials and Methods. Briefly, they represent lesions correctly localized and classified at the routine dose (250 eff. mAs with IR) by majority of readers.

  • c Dose-reconstruction configuration did not meet preset criteria for agreement with routine-dose interpretation, which was defined as agreement in 71 of the 83 examinations.