Institutional factors associated with varying CTC abnormality rates, detection of adenomas and cancers, and PPV
| Variable | Abnormality rate at CTC (%) | Detection of adenomas and cancers (%) | PPV (%) |
|---|---|---|---|
| Average radiologist experience | |||
| <300 cases | 154/474 (32.5) | 82/474 (17.3) | 82/134 (61.2) |
| 300–999 cases | 384/1006 (38.2) | 205/1006 (20.4) | 205/340 (60.3) |
| 1000+ cases | 450/1119 (40.2)* | 282/1119 (25.2)* | 382/400 (70.5)* |
| Average radiologist workload | |||
| <175 cases/radiologist/annum | 291/851 (34.2) | 145/851 (17.0) | 145/247 (58.7) |
| ≥175 cases/radiologist/annum | 697/1748 (39.9)† | 424/1748 (24.3)† | 424/627 (67.6)† |
| Interpretation strategy | |||
| Primary two-dimensional interpretation | 316/973 (32.5) | 183/973 (18.8) | 183/286 (64.0) |
| Three-dimensional interpretation | 711/1758 (40.4)† | 409/1758 (23.3)† | 409/625 (57.5) |
| Bowel preparation | |||
| Either purgation or tagging | 493/1456 (33.9) | 301/1456 (20.7) | 301/439 (68.6)† |
| Both purgation and tagging combined | 495/1143 (43.3)† | 268/1143 (23.4) | 268/435 (61.6) |
*χ2 Test for trend in proportions, p<0.05.
†χ2 Test, p<0.05 when compared with the other category of the same variable.
CTC, CT colonography; PPV, positive predictive value