Table 2

Intramodality and intermodality agreements of single and total erosion volume, measured on computed tomography (CT) and magnetic resonance imaging (MRI)

Reading A (mm3)

Reading B (mm3)

Mean of readings A and B (mm3)

Spearman ρ

Absolute difference (mm3)a

Absolute numerical difference (mm3)

Relative difference (%)b

Relative numerical difference (%)

Coefficient of variation


Intramodality agreement: CT (reading A) vs CT (reading B) and MRI (reading A) vs MRI (reading B)

Volume per erosion

CT (n = 135)

13 (4; 1–245)

14 (4; 1–264)

13 (4; 1–255)

0.92*

-1 (0; -28 to 12)

2 (1; 0–28)

-7 (0; -120 to 100)

29 (22; 0–120)

0.15 (0.11; 0–0.60)

MRI (n = 90)

17 (10; 1–132)

17 (11; 1–138)

17 (11; 1–133)

0.90*

0 (0; -23 to 18)

4 (3; 0–23)

0 (0; -100 to 86)

28 (25; 0–100)

0.14 (0.13 0–0.50)

Volume per person with erosions

CT (n = 17)

102 (49; 2–519)

108 (56; 3–535)

105 (55; 3–527)

0.99*

-6 (-2; -54 to 19)

12 (7; 1–54)

-10 (-6; -43 to 15)

16 (15; 3–43)

0.08 (0.07; 0.02–0.21)

MRI (n = 15)

101 (80; 5–409)

100 (78; 5–409)

100 (76; 5–409)

0.95*

1 (0; -23 to 18)

7 (5; 0–23)

2 (0; -22 to 25)

8 (6; 0–25)

0.04 (0.03; 0–0.13)

Intermodality agreement (CT vs MRI)c

Volume per erosion of all concordant erosions (n = 64)

CT

21 (5; 1–245)

22 (5; 1–255)

21 (5; 1–255)

0.55*

2 (-5; -55 to 132)

17 (9; 0–131)

-54 (-59; -174 to 167)

90 (92; 0–174)

0.46 (0.45; 0–0.87)

MRI

20 (13; 1–132)

19 (13; 1–138)

19 (13; 1–133)

Total volume per person of all concordant erosions (n = 15)

CT

88 (18; 1–514)

93 (23; 1–528)

91 (21; 1–521)

0.89*

8 (-7; -56 to 147)

40 (16; 4–147)

-48 (-63; -139 to 64)

72 (64; 6–139)

0.36 (0.32; 0.03–0.70)

MRI

83 (78; 5–374)

83 (62; 5–375)

83 (71; 5–375)

Total volume per person of all erosions (n = 19)

CT

91 (36; 0–519)

100 (49, 0–535)

94 (38; 0–527)

0.82*

15 (2; -60 to 118)

41 (31; 0–118)

13 (6; -129 to 200)

68 (52; 0–200)

0.34 (0.26; 0–1.0)

MRI

79 (67; 0–409)

79 (67; 0–409)

79 (63; 0–409)


Data presented as the mean (median; range). Reading A and reading B, volumes obtained at the first (reading A) and second (reading B) volume measurements, done by the same observer 1 week apart. The mean value of volumes obtained at reading A and B was used for the comparison of CT and MRI volumes. *P < 0.01. aIntramodality agreement, reading A minus reading B; intermodality agreement, CT erosion volume minus MRI erosion volume. bIntramodality agreement, positive values refer to larger erosion volume at reading A than reading B, and vice versa; intermodality agreement, positive values refer to larger erosion volume on CT than MRI, and vice versa. cValues on intermodality agreement are comparisons between CT and MRI erosions volumes.

Døhn et al. Arthritis Research & Therapy 2008 10:R25   doi:10.1186/ar2378

Open Data