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 Configurations |
No. of Successful Interpretations per Lower- Dose–Reconstruction Configuration |
JAFROC FOM (95% CI) | |||
|---|---|---|---|---|---|---|
| 2 of 3 | 3 of 3 | Cases 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 FBP | 44 (94%) | 39 (83%) | 30 | 48 | 78 | 0.846 (0.78–0.912) |
| 100 eff. mAs IR | 43 (92%) | 37 (79%) | 29 | 46 | 75 | 0.831 (0.764–0.898) |
| 100 eff. mAs FBP | 42 (89%) | 36 (77%) | 28 | 45 | 73 | 0.805 (0.732–0.878) |
| 50 eff. mAs IR | 41 (87%) | 32 (68%) | 26 | 47 | 73 | 0.795 (0.727–0.864) |
| 50 eff. mAs FBP | 38 (81%) | 31 (66%) | 25 | 47 | 72 | 0.789 (0.717–0.861) |
| 25 eff. mAs IR | 34 (72%) | 25 (53%) | 22 | 45 | 67c | 0.754 (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.