Table 5.
PPV and NPV of individual MRI features for discriminating complicated from simple appendicitis, as identified in the systematic review; for the data reported by Leeuwenburgh et al.,61 the PPV and NPV were calculated to exclude cases without appendicitis, based on the reported values; the data reported by Zhu et al.39 was excluded due to an unusually high prevalence of complicated appendicitis
| MRI feature | PPV | NPV |
|---|---|---|
| Appendiceal diameter > 7 mm61 | 26.3 (30/114) | 100 (2/2) |
| Periappendiceal fat infiltration61 | 26.4 (29/110) | 83.3 (5/6) |
| Periappendiceal fluid61 | 30.7 (27/88) | 89.3 (25/28) |
| Absence of intraluminal air61 | 24.5 (26/106) | 60 (6/10) |
| Appendicolith61 | 30.8 (16/52) | 78.1 (50/64) |
| Extraluminal appendicolith32 | 100 (1/1) | 73.5 (25/34) |
| Appendiceal wall defect32 | 75~85.7 (6/8 ~ 6/7) | 85.2~85.7 (23/27 ~ 24/28) |
| Appendiceal wall destruction61 | 51.9 (14/27) | 82.0 (73/89) |
| Phlegmon32 | 40.9~42.9 (9/22 ~ 9/21) | 92.3~92.9 (12/13 ~ 13/14) |
| Abscess32,61 | 55.6 (10/18), 85.7~100 (6/7 ~ 6/6) | 79.8 (79/99), 85.7~86.2 (24/28 ~ 25/29) |
| Extraluminal free air32,61 | 100 (1/1), 100 (2/2) | 75 (87/116), 75.8 (25/33) |
| Restricted diffusion of appendiceal wall61 | 27.3 (27/99) | 86.7 (13/15) |
| Restricted diffusion of appendiceal lumen61 | 27.9 (24/86) | 82.1 (23/28) |
| Restricted diffusion of focal collections61 | 55.6 (15/27) | 83.9 (73/87) |