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Intramodality and intermodality agreements of single and total erosion volume, measured on computed tomography (CT) and magnetic resonance imaging (MRI) |
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| 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 |
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| Intramodality agreement: CT (reading A) vs CT (reading B) and MRI (reading A) vs MRI (reading B) |
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| Volume per erosion |
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| 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 |
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| 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 |
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| Volume per erosion of all concordant erosions (n = 64) |
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| CT |
21 (5; 1–245) |
22 (5; 1–255) |
21 (5; 1–255) |
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| 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) |
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| MRI |
20 (13; 1–132) |
19 (13; 1–138) |
19 (13; 1–133) |
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| Total volume per person of all concordant erosions (n = 15) |
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| CT |
88 (18; 1–514) |
93 (23; 1–528) |
91 (21; 1–521) |
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| 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) |
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| MRI |
83 (78; 5–374) |
83 (62; 5–375) |
83 (71; 5–375) |
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| Total volume per person of all erosions (n = 19) |
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| CT |
91 (36; 0–519) |
100 (49, 0–535) |
94 (38; 0–527) |
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| 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) |
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| MRI |
79 (67; 0–409) |
79 (67; 0–409) |
79 (63; 0–409) |
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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 |
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