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Supplementary material uploaded as "supporting documents."
Appendices available on journal website
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Appendix 1: Description of lesions in the training set and global results for the participating centers
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1. Number of polyps per case.
Number of polyps
0
1
2
3
4
5
6
Number of case
26 (50%)
8 (15%)
6 (11%)
5 (10%)
1 (2%)
4 (8%)
2 (4%)
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2. Sizes and shapes of 71 polyps among 52 patients.
Diameter, mm
≤5
6–9
≥10
Shape
Pedunclated (Ip)
Sessile (Is)
Flat (II)
Lesions, n (%)
32 (45)
25 (35)
14 (20)
18 (25)
47 (66)
6 (8)
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12
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3. Global results and diagnostic value in per-patient analysis for centers involved in the training set
%
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Sensitivity
Mean
Median
Minimum
Maximum
83.84
88.46
33.33
96.15
Specificity
Mean
Median
Minimum
Maximum
80.40
80.77
60.00
100.00
Positive predictive
value (PPV)
Mean
Median
Minimum
Maximum
81.04
82.14
50.00
100.00
Negative predictive
value (NPV)
Mean
Median
Minimum
Maximum
84.85
85.71
66.67
95.65
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16
17
18
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4. Sensitivity (%) for lesion of any size and polyps ≥6 mm or polyps ≥10 mm
Mean
Median
Min
Max
20
21
22
Any size
47.59
49.30
10.00
64.79
≥6 mm
58.58
60.61
16.67
76.92
≥10 mm
63.48
64.29
0.00
85.71
4. Positive predictive value (%) for lesion of any size and polyp ≥6 mm or polyp ≥10 mm
Mean
Median
Min
Max
Any size
69.38
71.88
43.28
95.83
≥6 mm
77.90
82.76
50.00
100.00
≥10 mm
81.72
81.82
53.85
100.00
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All radiologists achieved a median detection rate of 49%, 95% confidence interval [CI] 33%–65%) for polyps of any diameter and median
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detection rates of 61% (95% CI 42%–69%) and 65% (95% CI 57%–79%) for polyps ≥ 6 mm or 10 mm, respectively.
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Appendix 2: Details of the per lesion analysis of the detection rates
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Table : Diagnostic value results of computed tomographic colonography (CTC) in per-lesion and per-patient analysis with segmental unblinded
colonoscopy and histology as reference method.
Sensitivity
Specificity
PPV
NPV
% (95% CI)
% (95% CI)
% (95% CI)
% (95% CI
30 (27–34)
NA
59 (54–64)
NA
≥6 mm
65 (57–72)
NA
59 (52–66)
NA
≥10 mm
75 (65–84)
NA
73 (62–81)
NA
6-9 mm
63 (51-75)
95 (93-96)
54 (43-66)
96 (94-98)
Any shape
62 (55–69)
NA
63 (56–70)
NA
Flat
46 (28–66)
NA
48 (29–68)
Sessile or pedunculated
64 (57–71)
NA
70 (62–76)
Any shape
74 (64–82)
NA
74 (65–83)
Flat
71 (42–92)
NA
71 (42–92)
Per-lesion analysis
Any lesion
Adenomas, according to size
Polyps, according to size and
shape
≥6 mm
Polyps ≥10 mm
NA
Sessile or pedunculated
74 (63–83)
NA
80 (69–89)
Any lesion
55 (50–61)
81 (76–85)
74 (69–79)
64 (60–69)
≥ 3 polyps < 10 mm
14 ( 8-23)
98 (97-99)
54 (33-73)
88 (85-90)
≥6 mm
69 (61–77)
91 (89–94)
67 (59–74)
92 (90–94)
≥10 mm
79 (67–87)
97 (95–98)
71 (60–81)
98 (96–99)
≥6 mm
71 (62–79)
91 (89–93)
61 (53–69)
94 (92–96)
≥10 mm
79 (67–89)
97 (95–98)
68 (57–79)
98 (97–99)
Per patient analysis (n = 737)
Polyps
Adenomas
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32
33
34
35
36
37
38
39
40
41
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PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval; NA, not applicable.
Appendix 3:
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Table : Sensitivity (per-lesion) of radiologists in detection of lesions of different types and sizes at computed tomographic colonoscopy (CTC),
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according to performance at initial training, and subsequent experience. The radiologists were divided into two equal subgroups, according to the
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median of the distribution of the variable of interest, and the pooled sensitivity was found for each subgroup.
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Variable of interest
Training performance:
% detection of polyps
of any size in training
set (median was 49%)
Training performance:
% detection of polyps
>5 mm in training set
(median was 61%)
Case volume in the study
(median number was
18)
Lesion group
Sensitivity of radiologists in
Sensitivity of radiologists in
lower half of distribution
upper half of distribution
%
95% CI
%
95% CI
Polyps any size
27*
22–31
44*
29–39
Polyps ≥6 mm
51†
41–61
72†
63–80
Polyps ≥10 mm
68
50–82
77
65–87
Adenomas ≥6 mm
51‡
39–62
77‡
67–85
Adenomas ≥10 mm
68
49–83
80
66–89
Polyps any size
26§
22–31
33§
29–38
Polyps ≥6 mm
50‡
40–60
72‡
63–80
Polyps ≥10 mm
66
49–80
79
66–88
Adenomas ≥6 mm
49‡
38–61
77‡
67–85
Adenomas ≥10 mm
67
48–82
80
67–90
Polyps any size
21¶
15–29
32¶
29–36
Polyps ≥6 mm
25‡
11–43
69‡
61–75
Polyps ≥10 mm
33¶
7–70
78¶
68–86
Potential number of
polyps for detection
(median number was
19)
47
48
49
50
51
Adenomas ≥6 mm
17‡
4–41
70‡
62–77
Adenomas ≥10 mm
20§
1–72
78§
68–87
Polyps any size
30
21–40
30
27–34
Polyps ≥6 mm
47*
30–65
65*
58–72
Polyps ≥10 mm
54
25–81
77
66–85
Adenomas ≥6 mm
46§
28–66
68§
60–76
Adenomas ≥10 mm
60
26–88
77
66–86
* < 0.05; † < 0.002; ‡ < 0.001; § < 0.03; ¶ <0.01
PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval; NA, not applicable.
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Appendix 4: Additional correlation between the detection rate during the training set and cases included in the daily practice
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The mean detection rate for polyps ≥6 mm in the first and second half of cases included by each radiologist were 55 ± 8% and 69 ± 7% the
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difference being 16 ± 8%. There was no correlation between this difference and the sensitivity for detection of polyps ≥6 mm in the training set:
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however this latter was significantly (p< 0.03) correlated only to the detection rate in the second half of cases included in the study
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Appendix 5:
Figure 2. Bland–Altman plot of true-positive polyps diameter estimates during optical colonoscopy and computed tomographic colonoscopy
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(CTC) according to the mean of the the two estimates of polyp size; STD, standard deviation of the difference.
Figure 2: Blant and Altman plot for polyps diameter measured by
CTC and videocolonoscopy for the 272 true-positive cases
Difference between estimates of polyp diameter at
CTC and at optical colonoscopy, mm
40
30
20
10
Mean difference + 1.96 STD
Mean difference + 1 STD
0
Mean difference
Mean difference − 1 STD
-10
Mean difference − 1.96 STD
-20
0
10
20
30
40
50
60
Polyp diameter, mean of the estimates from the two methods, mm
62
63
64
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Appendix 6: CTC procedure description
All examinations were performed with multidetector CT scanners with a minimum of 16 rows. The CT technique involved the use of 0.5- to 1.0-
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mm collimation and scanner settings of 120 kVp and 50–75 effective mA. A standard reconstruction algorithm was used, with images were
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reconstructed to slice thicknesses of 1.0 to 1.25 mm, with an interval of 0.8 to 1 mm.
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The CTC examinations were interpreted, immediately before videocolonoscopy, by a radiologist using either a primary two-dimensional (2D)
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reading method with 3D problem-solving, or a primary 3D reading method with the capability to display 2D reformatted images.
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The radiologists made their interpretations without knowledge of colonoscopic results, and were instructed to record all lesions, noting whether
they measured ≥6 mm in diameter.
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Appendix 7: Estimates of polyp size
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Estimates of polyp diameter from optical colonoscopy and CTC correlated significantly, but the radiologist–endoscopist agreement for their
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classification in three size categories (i.e., ≤5 mm, 6–9 mm, and 10 mm or more) was moderate with a kappa index of 0.55 (95% CI 0.46–0.63).
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The Bland–Altman method, used only for polyps viewed both at CTC and videocolonoscopy (true positives) (Figure 2, in Appendix 5 online-
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only) showed that the overall diameter difference (mean ± SD) was 1.92 ± 0.40 mm for polyps >5 mm, 3.29 ± 0.68 mm for those >10 mm, and
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6.19 ± 1.49 mm for those >20 mm.
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Appendix 8: the Standard for Reporting of diagnostic Accuracy STARD contingency tables in per-patient analysis
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VP = True Positive
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FN = False Négative
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FP = False Positive
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VN = True Négative
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89
90
Standard = lesion find with colonoscopy after the first withdrawal or the second examination and withdrawal required by the CT
colonoscopy (CTC) results (false negative of colonoscopy)
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Numbers in tables are expressed as patient numbers.
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93
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Patients with Polyps of any size
standard
Détecté
observed
Non observed
Total
205
71
276
(VP)
(FP)
165
296
(FN)
(VN)
370
367
CTC
Non détecté
Total
95
96
Patients with Polyps ≥ 6 mm
standard
461
737
observed
observed
Non observed
Total
102
51
153
(VP)
(FP)
45
539
(FN)
(VN)
147
590
737
observed
Non observed
Total
57
35
92
(VP)
(FP)
34
611
(FN)
(VN)
91
646
CTC
Non
observed
Total
584
97
98
Patients with Polyps 6-9 mm
standard
observed
CTC
Non
observed
Total
99
100
Patients with Polyps ≥ 10 mm
standard
645
737
observed
observed
Non observed
Total
55
22
77
(VP)
(FP)
15
645
(FN)
(VN)
70
667
CTC
Non
observed
Total
101
102
660
737
103
Patients with ≥ 3 Polyps < 10 mm
standard
observed
Non observed
Total
14
12
26
(VP)
(FP)
85
626
(FN)
(VN)
99
638
737
observed
Non observed
Total
136
97
233
(VP)
(FP)
108
396
observed
CTC
Non
observed
Total
711
104
105
106
107
108
Patients with Adénomas of any size
standard
observed
CTC
Non
observed
504
Total
(FN)
(VN)
244
493
737
observed
Non observed
Total
85
54
139
(VP)
(FP)
35
563
(FN)
(VN)
120
617
737
observed
Non observed
Total
43
36
79
(VP)
(FP)
25
633
109
110
Patients with Adénomas ≥ 6 mm
standard
observed
CTC
Non
observed
Total
598
111
112
Patients with Adénomas 6-9 mm
standard
observed
CTC
Non
observed
658
(FN)
(VN)
68
669
737
observed
Non observed
Total
50
23
73
(VP)
(FP)
13
651
(FN)
(VN)
63
674
737
observed
Non observed
Total
9
13
22
Total
113
114
Patients with Adénomas ≥ 10 mm
standard
observed
CTC
Non
observed
Total
664
115
116
117
Patients with ≥ 3 adénomes < 10 mm
118
standard
CTC
observed
Non
observed
Total
119
120
121
122
(VP)
(FP)
38
677
(FN)
(VN)
47
690
715
737