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Perforated and Nonperforated Appendicitis: Defect in Enhancing Appendiceal Wall—Depiction with Multi–Detector Row CT¹

¹ From the Departments of Radiology (M.T., K.T.) and Surgery (I.K.), Ishinomaki Red Cross Hospital, 1-7-10 Yoshino, Ishinomaki, Miyagi 986-8522, Japan; and Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan (M.T., K.T., T.I., T.Y., M.K., S.H., S.T.). From the 2004 RSNA Annual Meeting. Received November 21, 2005; revision requested January 20, 2006; revision received May 20, 2007; accepted June 12; final version accepted July 23. Address correspondence to M.T. (e-mail: m_tsuboi{at}rad.med.tohoku.ac.jp).

	ABSTRACT

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Purpose: To retrospectively evaluate the accuracy of multi–detector row helical computed tomography (CT) with intravenous contrast material and without oral contrast material for depiction of perforated appendicitis.

Materials and Methods: This study was approved by the institutional review board; informed consent was waived. CT images in 102 patients (60 male patients, 42 female patients; age range, 4–82 years; mean age, 37.3 years) with surgically and pathologically proved appendicitis who were examined between January 2000 and December 2002 were retrospectively reviewed. Original transverse sections at 3- or 2-mm collimation and 1.5- or 1.0-mm intervals were viewed by using cine mode observation. Two independent observers evaluated five specific findings (defect in enhancing appendiceal wall, abscess, phlegmon, extraluminal air, and extraluminal appendicolith). Sensitivity, specificity, and accuracy of the specific findings in the diagnosis of perforated appendicitis were evaluated.

Results: Perforated appendicitis was present in 40 patients, and nonperforated appendicitis was present in 62 patients. A defect in the enhancing appendiceal wall was present in 38 patients in the perforated group. Two patients in the nonperforated group had false-positive findings for a defect in the enhancing appendiceal wall. Sensitivity, specificity, and accuracy of this finding in the diagnosis of perforation were 95.0%, 96.8%, and 96.1%, respectively. Sensitivities for abscess, extraluminal air, and extraluminal appendicolith were 37.5%, 22.5%, and 32.5%, respectively. These three findings were not found in patients with nonperforated appendicitis. Phlegmon was seen in 16 patients in the perforated group and in three patients in the nonperforated group. Sensitivity, specificity, and accuracy of phlegmon in the diagnosis of perforation were 40.0%, 95.2%, and 73.5%, respectively.

Conclusion: Multi–detector row CT allows an accurate (96.1%) diagnosis of appendiceal perforation by the depiction of a defect in the contrast material–enhanced appendiceal wall.

© RSNA, 2008

	INTRODUCTION

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Differentiation of perforated appendicitis from nonperforated appendicitis is an important issue (1–4). Different management options, such as administration of antibiotics and/or drainage with or without interval surgery, are frequently chosen for perforated appendicitis instead of traditional immediate open appendectomy because appendiceal perforation confers an increased risk for complications after immediate surgery for acute appendicitis.

The optimal approach in the treatment of patients with appendicitis is a topic of some controversy, and a therapeutic standard has yet to be established. Nevertheless, the patient's clinical status must be accurately diagnosed before treatment. Differentiating perforated from nonperforated appendicitis is important in selecting an adequate therapeutic approach.

Single-section helical computed tomography (CT) has been successfully employed for the examination of patients suspected of having appendicitis and has improved diagnostic accuracy and reduced the negative appendectomy rate (5–10). Investigation of diagnosing appendiceal perforation by using CT has been infrequently reported. Results of a few studies (11,12) have showed the usefulness of single-section helical CT in the differentiation between perforated and nonperforated appendicitis. However, these study results did not show high accuracy for any single finding.

Multi–detector row helical CT enables an extensive area to be scanned with a small section thickness in a short time, resulting in excellent spatial resolution (13). Thus, the purpose of our study was to retrospectively evaluate the accuracy of multi–detector row CT with intravenous contrast material and without oral contrast material for the depiction of perforated appendicitis.

	MATERIALS AND METHODS

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Patients
This study was approved by our institutional review board at Ishinomaki Red Cross Hospital, and informed consent was waived. In a study by Horrow et al (11) on differentiation between perforated and nonperforated appendicitis by using single-section helical CT, sensitivity of a focal defect in appendiceal wall enhancement was 64%. In our preliminary investigation of a small number of series, sensitivity of this finding at multi–detector row CT was estimated to be more than 90%. To verify this high sensitivity to be statistically significant, the necessary number of patients with perforation and the number of patients without perforation was estimated to be at least 40 for each group of patients when an error of .05 and a β error of .2 were applied.

One hundred five consecutive patients (62 male patients, 43 female patients; age range, 4–89 years; mean age, 37.5 years) with surgically and pathologically proved appendicitis examined with CT between January 2000 and December 2002 were considered. There were 42 cases with perforated appendicitis and 60 cases with nonperforated appendicitis, with both numbers satisfying the minimal number (n = 40) required for verifying statistical significance, as mentioned above. CT images in these 105 patients were, therefore, retrospectively reviewed. We excluded two patients who underwent surgery more than 24 hours after CT and one patient whose appendix was torn during surgery, which made the presence or absence of perforation unidentifiable. Thus, 102 patients (60 male patients, 42 female patients; age range, 4–82 years; mean age, 37.3 years) who underwent surgery within 24 hours (range, 1–24 hours; mean time, 7.92 hours) of CT scanning and who had confirmation of the presence or absence of perforation were included in this study.

All appendectomies were initially performed with laparoscopy. If the surgery was difficult at laparoscopy because of severe adhesions and/or severe inflammation around the appendix, laparoscopy was converted to open surgery.

A final diagnosis of appendiceal perforation was made when at least one of two criteria was met: (a) an experienced abdominal surgeon (I.K., 24 years of experience) observed macroscopically evident appendiceal perforation at surgery or (b) transmural inflammatory cell infiltrate with necrosis was found at pathologic examination.

Imaging
A multisection CT scanner (Aquilion; Toshiba, Tokyo, Japan) was used. In 86 patients examined between January 2000 and August 2002, scanning was performed with the following parameters: four detector rows, 0.5 second per rotation, 3- or 2-mm collimation, and 33 or 22 mm/sec table increment (pitch, 1.375). In 16 patients examined between September 2002 and December 2002, scanning was performed with the following parameters: eight detector rows, 0.5 second per rotation, 2-mm collimation, and 40 mm/sec table increment (pitch, 1.25). All patients underwent an abdominal and pelvic scan starting from the top level of the diaphragm through the level of the ischial tuberosity. Duration of scanning at four-detector CT was less than 20 seconds, and duration of scanning at eight-detector CT was less than 15 seconds. Before scanning was started, 70–90 mL of contrast material containing 300 milligrams of iodine per milliliter (iohexol, Omnipaque; Daiichi Pharmaceutical, Tokyo, Japan) was injected into an antecubital vein at a rate of 0.8–1.0 mL/sec. The scan delay after the start of injection was 90 seconds. The total volume and injection speed of intravenous contrast material were adjusted according to patient age and body weight. The total examination time, including the time for patient preparation, was less than 15 minutes. Transverse sections were reconstructed with a 3- or 2-mm section thickness at 1.5- or 1.0-mm intervals.

Image Evaluation
Images were retrospectively reviewed at a stand-alone workstation (Zio M900 Quadra; Amin, Tokyo, Japan) by using cine mode display, in which multiple original transverse sections can be viewed by scrolling through the images. Images were evaluated by two radiologists (M.T., 12 years of experience; K.T., 17 years of experience) to attempt to identify the appendix. They were blinded to the results of surgery and pathologic examination. In cases of disagreement, consensus was reached through mutual discussion. By using the method of Horrow et al (11), we assessed five specific findings and three groups with a combination of those specific findings on which they placed a special emphasis.

Specific findings.—The five specific findings indicative of perforated appendicitis were defect in enhancing appendiceal wall, abscess, phlegmon, extraluminal air, and extraluminal appendicolith.

A defect in the enhancing appendiceal wall was characterized by an interruption in the enhancement of the appendiceal wall. This sign was judged to be positive only when it was unequivocal and was considered negative when it was difficult to judge. An abscess was characterized by a clearly delineated, discrete collection with rim enhancement. A phlegmon was characterized by diffuse but marked inflammation of the periappendiceal fat, with poorly defined fluid collections. Extraluminal air and appendicolith were characterized by the presence of air outside the lumen and the presence of an appendicolith outside the lumen, respectively.

Three groups with combined specific findings.—Horrow et al (11) achieved high diagnostic accuracy by combining three or four specific CT findings. Therefore, we evaluated the same three groups of combined CT findings described in their report. Group 1 included all patients with one or more of the classic findings of appendiceal perforation: abscess, extraluminal air, and extraluminal appendicolith. Group 2 included all patients with any of these three findings or a phlegmon. Group 3 included all patients with any of the three findings or a defect in the enhancing appendiceal wall. Thus, group 1 was a subset of group 2 and a subset of group 3.

Statistical Analysis
Each patient was assigned to either a perforated group or nonperforated group on the basis of surgical and pathologic findings. Sensitivity, specificity, and accuracy of the specific findings in the diagnosis of perforated appendicitis were evaluated. The statistic was used to assess interobserver agreement in the interpretation of the specific findings. We used a commercially available software package (SPSS, version 11.0.1 J; SPSS, Chicago, Ill).

	RESULTS

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On the basis of surgical and pathologic findings, 40 patients (12 female patients, 28 male patients; age range, 4–89 years; mean age, 45.3 years) had perforated appendicitis, while 62 patients (29 female patients, 33 male patients; age range, 5–71 years; mean age, 32.2 years) had nonperforated appendicitis (Fig 1).

View larger version (15K): [in this window] [in a new window] [Download PPT slide]   Figure 1: Chart shows overall distribution of results in 105 patients with acute appendicitis.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 2a: (a–c) Consecutive transverse CT images in 20-year-old man with perforated appendicitis show only an enhancing appendiceal wall defect (arrow). All of the appendix (arrowheads) is traceable from its origin. Ce = cecum.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 2b: (a–c) Consecutive transverse CT images in 20-year-old man with perforated appendicitis show only an enhancing appendiceal wall defect (arrow). All of the appendix (arrowheads) is traceable from its origin. Ce = cecum.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 2c: (a–c) Consecutive transverse CT images in 20-year-old man with perforated appendicitis show only an enhancing appendiceal wall defect (arrow). All of the appendix (arrowheads) is traceable from its origin. Ce = cecum.

View larger version (149K): [in this window] [in a new window] [Download PPT slide]   Figure 3: Transverse CT image in 24-year-old man with perforated appendicitis shows the appendix (arrowheads), enhancing appendiceal wall defect (arrow), and abscess (Ab).

View larger version (149K): [in this window] [in a new window] [Download PPT slide]   Figure 4a: Transverse CT images with intravenous contrast medium enhancement in 51-year-old man with perforated appendicitis. The appendix (arrowheads) is traceable. (a) Image shows cecum (Ce) and phlegmon (Ph). (b) Image shows defect (arrow) of appendiceal wall enhancement and phlegmon (Ph).

View larger version (152K): [in this window] [in a new window] [Download PPT slide]   Figure 4b: Transverse CT images with intravenous contrast medium enhancement in 51-year-old man with perforated appendicitis. The appendix (arrowheads) is traceable. (a) Image shows cecum (Ce) and phlegmon (Ph). (b) Image shows defect (arrow) of appendiceal wall enhancement and phlegmon (Ph).

View larger version (145K): [in this window] [in a new window] [Download PPT slide]   Figure 5a: Transverse CT images in 62-year-old man with perforated appendicitis. The appendix (arrowheads) is traceable. (a) Image shows defect (straight arrow) of appendiceal wall enhancement, abscess (Ab), and extraluminal air (curved arrow). (b) Image shows abscess (Ab) and extraluminal appendicolith (arrow).

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 5b: Transverse CT images in 62-year-old man with perforated appendicitis. The appendix (arrowheads) is traceable. (a) Image shows defect (straight arrow) of appendiceal wall enhancement, abscess (Ab), and extraluminal air (curved arrow). (b) Image shows abscess (Ab) and extraluminal appendicolith (arrow).

View larger version (151K): [in this window] [in a new window] [Download PPT slide]   Figure 6: Transverse CT image of false-positive sign in 17-year-old female patient with nonperforated appendicitis. Image shows enhancing appendiceal wall defect (arrow). However, the appendix (arrowheads) was not found to be perforated at surgery.

	DISCUSSION

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Of the three groups of combined findings, group 3 had the best accuracy (96.1%). However, that was for the single finding of enhancing appendiceal wall defect. Group 2 had a lower diagnostic accuracy than group 3.

There have been many studies concerning CT diagnosis of appendicitis, and its clinical usefulness has been well established (5–10,14). Ultrasonographic (US) examinations for appendicitis have also been studied. However, the diagnostic performance of US depends on the technique of the examiners, and identifying the appendix is difficult if the appendix is located behind the ascending colon (15–18).

In patients with early appendiceal perforation without substantial periappendiceal inflammation, prompt appendectomy may be recommended before development of such inflammation, which can worsen the patient's condition and increase the risk of postoperative complications. For such a therapeutic strategy to be undertaken, the early stage of perforated appendicitis without development of inflammation must be accurately diagnosed. We believe this may be accomplished by detecting the single finding of an enhancing appendiceal wall defect without the presence of the other four specific findings we evaluated. Furthermore, the finding of an enhancing appendiceal wall defect should enable the differential diagnosis of perforated appendicitis from other inflammatory diseases that can manifest with similar symptoms.

Despite the existence of many studies on CT diagnosis of appendicitis, to our knowledge, few have focused on the differential diagnosis of perforated and nonperforated appendicitis. A study by Horrow et al (11) involved single-section helical CT with several scanning protocols. Specifically, the section thickness ranged from 5 to 10 mm (11). In addition, some examinations were performed with oral contrast material and others were performed with intravenous contrast material. In that study, a defect of the enhancing appendiceal wall was most sensitive as a single finding, but its sensitivity remained 64%. On the other hand, a combination of four findings (abscess, phlegmon, extraluminal air, extraluminal appendicolith) had higher diagnostic accuracy. However, the use of a combination of several findings may be complicated in an emergency situation. In another study (12), specificity of a focal defect of the enhancing appendiceal wall was also lower than in our study. In our study, there were two false-positive findings of an apparent defect in the enhancing appendiceal wall. Thin-section CT may more likely be associated with artifacts, such as low-attenuation artifacts in the appendiceal wall due to nearby bones and/or intestinal peristalsis. Such artifacts can be misdiagnosed as focal defects of the enhancing wall. Therefore, this potential problem should be kept in mind when interpreting images.

There were two false-negative diagnoses of a perforated appendix in our study. The exact reasons for them are unclear, but we suspect that narrowing of the appendiceal lumen after perforation might have resulted in shrinkage and obscuration of the defect, making detection impossible.

Although the diagnosis of perforated appendicitis in our study was based on surgical and/or pathologic findings, our study had limitations. Minor injury of the appendix during laparoscopic or open surgery could have caused erroneous pathologic findings of perforation, although one patient with a surgical tear of the appendix was excluded from our study. Because microscopic examination was performed for a restricted portion (that with the most severe inflammation), a different site with perforation might not have been examined. Furthermore, appendiceal perforation that had been absent at CT scanning could have occurred during the 24 hours between CT scanning and surgery.

Multi–detector row CT can accurately depict perforated and nonperforated appendicitis. Detecting a defect in the enhancing appendiceal wall by using cine mode display of transverse thin-section CT images allowed 96.1% accuracy for diagnosing appendiceal perforation.

	ADVANCE IN KNOWLEDGE

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• Detecting a defect in the enhancing appendiceal wall by using cine mode display of transverse thin-section CT images allowed 96.1% accuracy for diagnosing appendiceal perforation.
  

	IMPLICATION FOR PATIENT CARE

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• A defect in the enhancing appendiceal wall at multi–detector row CT is highly accurate for appendiceal perforation.
  

	ACKNOWLEDGMENTS

 
The authors thank Shunji Mugikura, MD, PhD, for his contribution to the data review and statistical analysis.

	FOOTNOTES

 
Guarantors of integrity of entire study, M.T., K.T., I.K., M.K., S.T.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, M.T., K.T., M.K.; clinical studies, M.T., K.T., I.K., M.K., T.I.; statistical analysis, M.T., K.T.; and manuscript editing, M.T., K.T., T.Y., S.H., S.T.

Authors stated no financial relationship to disclose.

	References

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1. Hale DA, Molloy M, Pearl RH, Schutt DC, Jaques DP. Appendectomy: a contemporary appraisal. Ann Surg 1997;225:252–261. [CrossRef][Medline]
2. Reid RI, Dobbs BR, Frizelle FA. Risk factors for post-appendicectomy intra-abdominal abscess. Aust N Z J Surg 1999;69:373–374. [CrossRef][Medline]
3. Oliak D, Yamini D, Udani VM, et al. Nonoperative management of perforated appendicitis without periappendiceal mass. Am J Surg 2000;179:177–181. [CrossRef][Medline]
4. Willemsen PJ, Hoorntje LE, Eddes EH, et al. The need for interval appendectomy after resolution of an appendiceal mass questioned. Dig Surg 2002;19:216–220. [CrossRef][Medline]
5. Wijetunga R, Tan BS, Rouse JC, et al. Diagnostic accuracy of focused appendiceal CT in clinically equivocal cases of acute appendicitis. Radiology 2001;221:747–753. [Abstract/Free Full Text]
6. Raptopoulos V, Katsou G, Rosen MP, et al. Acute appendicitis: effect of increased use of CT on selecting patients earlier. Radiology 2003;226:521–526. [Abstract/Free Full Text]
7. Kamel IR, Goldberg SN, Keogan MT, et al. Right lower quadrant pain and suspected appendicitis: nonfocused appendiceal CT—review of 100 cases. Radiology 2000;217:159–163. [Abstract/Free Full Text]
8. Sivit CJ, Applegate KE, Berlin SC, et al. Evaluation of suspected appendicitis in children and young adults: helical CT. Radiology 2000;216:430–433. [Abstract/Free Full Text]
9. Bendeck SE, Nino-Murcia M, Berry GJ, et al. Imaging for suspected appendicitis: negative appendectomy and perforation rates. Radiology 2002;225:131–136. [Abstract/Free Full Text]
10. Kaiser S, Frenckner B, Jorulf HK. Suspected appendicitis in children: US and CT—a prospective randomized study. Radiology 2002;223:633–638. [Abstract/Free Full Text]
11. Horrow MM, White DS, Horrow JC. Differentiation of perforated from nonperforated appendicitis at CT. Radiology 2003;227:46–51. [Abstract/Free Full Text]
12. Choi YH, Fischer E, Hoda SA, et al. Appendiceal CT in 140 cases: diagnostic criteria for acute and necrotizing appendicitis. Clin Imaging 1998;22:252–271. [CrossRef][Medline]
13. Takase K, Sawamura Y, Igarashi K, et al. Demonstration of the artery of Adamkiewicz at multi–detector row helical CT. Radiology 2002;223:39–45. [Abstract/Free Full Text]
14. Jacobs JE, Birnbaum BA, Macari M, et al. Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material. Radiology 2001;220:683–690. [Abstract/Free Full Text]
15. Callahan MJ, Rodriguez DP, Taylor GA. CT of appendicitis in children. Radiology 2002;224:325–332. [Abstract/Free Full Text]
16. Birnbaum BA, Wilson SR. Appendicitis at the millennium. Radiology 2000;215:337–348. [Abstract/Free Full Text]
17. Quillin SP, Siegel MJ, Coffin CM. Acute appendicitis in children: value of sonography in detecting perforation. AJR Am J Roentgenol 1992;159:1265–1268. [Abstract/Free Full Text]
18. Puylaert JB, Rutgers PH, Lalisang RI, et al. A prospective study of ultrasonography in the diagnosis of appendicitis. N Engl J Med 1987;317:666–669. [Abstract]

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