1. Right Lower Quadrant Pain: Value of the Nonvisualized Appendix in Patients at Multidetector CT
Suvranu Ganguli, MD, Vassilios Raptopoulos, MD, Fabio Komlos, MD, Bettina Siewert, MD and Jonathan B. Kruskal, MD, PhD
Radiology 2006;241:
MED96
蘇熙淵

2. Introduction
The most common cause of acute abdominal emergency requiring surgical intervention is acute appendicitis
Other causes of abdominal pain, however, can mimic appendicitis, such as colitis, diverticulitis, pelvic inflammatory disease, and renal calculi.
CT has become increasingly used in the work-up of right lower quadrant pain.

3. CT scans obtained for RLQ pain, the appendix is not visualized
CT scans obtained for RLQ pain, the appendix is not visualized. two recent reports, 13% &14 %
Nonvisualization of the appendix on transverse CT scans may safely be used to exclude acute appendicitis if no secondary CT findings of appendicitis are present. -- Nikolaidis et al
advances in multidetector CT , enhance the visualization of the appendix strengthen the confidence of negative

4. Purpose
To retrospectively determine the value of the nonvisualized appendix at multidetector computed tomography (CT) in patients with acute right lower quadrant pain in whom appendicitis was a consideration.

5. Materials & Methods

6. Patient Selection and Study Design
Retrospective review of all consecutive abdominal CT scans
April 29 to October 31, 2003.
ER record "right lower quadrant pain"
CT reports classified four categories
positive for appendicitis,
negative for appendicitis (normal appendix and normal results),
alternative acute diagnosis other than appendicitis,
appendix not visualized.

7. Imaging Technique Protocol
eight–detector row CT scanner (Lightspeed Ultra; GE Medical Systems, Milwaukee, Wis).
oral contrast agent (600–900 mL of barium sulfate ) 60–90 minutes before scanning
IV contrast (100–150 mL of ioversol ; rate 2.5 mL/sec), 60 seconds before scanning.

8. A single scan lung base to the symphysis pubis 1.25-mm collimation
Total in 10–15 seconds
routine 5-mm-thick continuous transverse sections & continuous coronal sections
Additional thin sections /interactive multiplanar images were not obtained

9. Image Analysis
an abdominal imaging attending physician and a radiology resident
Normal appendix : <6 mm ;lacked a thickened enhancing wall ;no intraluminal calcifications, no periappendical stranding.
appendicitis :thickened enhancing wall ;>8 mm. 6 ~8 mm with periappendiceal stranding

10. Clinical Follow-up
appendix was not visualized  retrospective chart review
To those loss f/u after MBD, authors asked institutional review board–approved questions to determine whether they had appendicitis at the time of CT examination.

11. Statistical Analysis
Descriptive statistics of the age and sex of the patients in the four groups
x2 test for sex and t test for age , P<.05
statistical software (SPSS )

12. Results

13. 400 examinations, 132 (33.0%) male ;268 (67.0%) ages : 16 ~ 88 yrs
All oral contrast ; IV contrast 27 (6.8%)
normal appendix /CT without for abdominal pain: 182 (45.5%)
79 patients (19.8%) with other causes
7.pyelonephritis or renal infarction ( 3)
8 small-bowel obstruction ( 3)
9volvulus ( 2)
10 ruptured ovarian cyst or dermoid ( 2)
11tubo-ovarian abscess ( 2)
12.bladder outlet obstruction (1)
13pelvic arteriovenous malformation (1).
1.inflammatory bowel disease or colitis ( 26),
2.diverticulitis ( 15)
3 obstructing nephrolithiasis (11),
4. acute cholecystitis ( 5)
5 typhilitis / mesenteric adenitis(4)
6.cancer (4)

14. 80 (20.0 %) with Dx of acute appendicitis by CT
59 patients (14.8% ) :appendix was not visualized
9/59 not f/u , MBD in good condition & not return ER
3/59 (exploration /appendectomy) without finding in CT. Pathology: no evidence
There was no statistically significant difference between groups regarding mean age or sex

15. 50 could be f/u in 59 patients whose appendix was not visualized:
46 note; 4 questionnaire
49 without related S/S
49(98%) patients with a nonvisualized appendix who were negative for appendicitis
1 return 15 wks later, acute appendicitis ; initially 11 days after C/S, Dx: postoperative infection of unclear etiology ; 24hr IV A/B

16. 80 with Dx of acute appendicitis in CT
6 :Tx with A/B without op, improved
74 appendectomy:
70 confirm appendicitis;
1 no finding
3 appendix Ca, endometriosis, ruptured ovarian cyst
95% (70 / 74) patients with multidetector CT findings that were positive for appendicitis

17. Discussion

18. acute appendicitis (inflamed appendix):
use of CT for RLQ pain  increased availability ;fast, accurate, & operator independent.
an appendix that is visualized at CT and that has a normal appearance can be used to exclude appendicitis
acute appendicitis (inflamed appendix):
distended with fluid.
>8 mm without surrounding inflammation, >6 mm with surrounding changes.
wall is usually thickened & increased mural enhancement with IV contrast .
Appendicoliths & periappendiceal inflammation

19. This study: positive: 95%
CT in Dx RLQ pain:
sensitivity98%,
specificity99%,
positive predictive value97%,
negative predictive98%
This study: positive: 95%

20. Nonvisualization appendix :15% of the scans in this study
Uncomfortable for discharging : leads to increased obs time & admission
This study, high percentage (98%) of negative allow to exclude appendicitis when the appendix is not visualized at CT.

21. Similarities: retrospective; multidetectorCT. Differences:
The absence of a distinctly visualized appendix in the right lower quadrant and the absence of secondary findings can be used to exclude appendicitis. — Nikolaidis
Similarities: retrospective; multidetectorCT.
Differences:
No of nonvisualized with f/u ;
Dr for image Dx,
No of loss f/u (hospital records & interviews)
group

22. Improve identify appendix: contrast, focused scan
Protocol in this study is optimal for D/D
Imaging protocol use in susp appendicitis: contrast agents are routinely given with 79%IV, 82% oral, and 32%rectal
in practice ,most common CT oral & IV contrast

23. P’t with nonvisualized appendix had surgery according :history, PE, lab
CT scans nonvisualized appendix highly correspond to negative for appendicitis
Clinicians should be more comfortable with conservative care in this group of patients.

24. Limitation the retrospective nature of follow-up
15% of patients were lost to follow-up

25. Conclusion
Patients with right lower quadrant pain that is unexplained at multidetector CT, a nonvisualized appendix is a reliable predictor of the absence of acute appendicitis.

26. Thanks for your attention!!