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(Radiology. 1999;213:341-346.)
© RSNA, 1999

Emergency Radiology

Suspected Acute Appendicitis: Nonenhanced Helical CT in 300 Consecutive Patients1

Michael J. Lane, MD, David M. Liu, MD, Mylinh D. Huynh, MD, R. Brooke Jeffrey, Jr, MD, Robert E. Mindelzun, MD and Douglas S. Katz, MD

1 From the Department of Radiology, Brooke Army Medical Center, 3851 Roger Brooke Dr, Ft Sam Houston, TX 78234-6200 (M.J.L.); the Department of Radiology, Stanford University, Calif (D.M.L., M.D.H., R.B.J., R.E.M.); the Department of Radiology, University of British Columbia, Victoria, Canada (D.M.L.); and the Department of Radiology, Winthrop University Hospital, Mineola, NY (D.S.K.). From the 1998 RSNA scientific assembly. Received September 24, 1998; revision requested October 26; final revision received March 11, 1999; revision accepted June 9. Address reprint requests to M.J.L.


   Abstract
TOP
 Abstract
Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
PURPOSE: To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis.

MATERIALS AND METHODS: Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (>6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both.

RESULTS: There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%.

CONCLUSION: Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.

Index terms: Abdomen, acute conditions, 751.291 • Abdomen, CT, 70.12111, 70.12115 • Appendicitis, 751.291 • Computed tomography (CT), helical, 70.12115


   Introduction
TOP
 Abstract
 Introduction
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Recently, thin-section helical computed tomography (CT) for examining patients suspected to have acute appendicitis has been shown to be a highly accurate, rapid, and cost-effective technique (1–4). Accuracy rates with a variety of CT techniques that use different combinations of oral, rectal, and intravenous contrast agents have ranged from 93% to 98% (1–3,5) for patients suspected to have acute appendicitis. In a study by de Dombal (6) for the Research Committee of the World Organization of Gastroenterology, results of a review of 10,682 patients with acute abdominal pain showed that acute appendicitis accounted for 28% of these cases. Therefore, the ability to quickly and accurately triage a large group of patients is critical to optimal use of available facilities and personnel in any busy practice or emergency department.

Approximately 20%–33% of patients suspected to have acute appendicitis will present with atypical clinical findings and laboratory test results (7,8); numerous disorders may manifest with signs and symptoms that mimic those of acute appendicitis. While the diagnosis of acute appendicitis is still largely thought to be a clinical one, a meaningful number of patients are found to have normal appendices at surgery. The erroneous diagnosis of this acute condition has led to a high rate of inappropriate removal of the normal appendix of 8%–30%. A rate as high as 20% is considered acceptable in the surgery literature (8–10). This high rate needs to be balanced with the problem of being overrestrictive in the diagnosis of acute appendicitis, which may allow nonperforated appendices to progress to perforation and peritonitis (9).

Elimination of the delay and risk of administering contrast material allows thin-section helical CT performed without oral, rectal, or intravenous administration of contrast material to be ideally suited for the evaluation of patients with suspected acute appendicitis. Also, the ability to accurately diagnose acute appendicitis and the myriad of disorders that clinically mimic it should reduce the number of unnecessary appendectomies.


   MATERIALS AND METHODS
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 References
 
Three hundred consecutive patients were examined prospectively by using transverse nonenhanced thin-section helical CT for the detection of suspected acute appendicitis. The patients included 156 female and 144 male patients ranging in age from 8 to 86 years. All patients were included regardless of age. Entrance criteria were based on the clinical judgment of the referring physicians. Patients were referred from the departments of emergency medicine and surgery.

All CT scans were obtained with a helical CT scanner (HiSpeed Advantage; GE Medical Systems, Milwaukee, Wis). A single breath-hold helical scan from the top of the T12 vertebral body to the pubic symphysis was obtained by using 5-mm beam collimation and 8 mm/sec table speed (pitch, 1.6; 120 kVp; 240–270 mAs). No oral, rectal, or intravenous contrast material was administered. Images were reconstructed and photographed at 5-mm intervals by using standard soft-tissue windows (width, 400 HU; level, 40 HU). Patients were instructed to hold their breath on inspiration for 45 seconds. Total examination time was approximately 10 minutes.

The primary criterion used to establish the diagnosis of acute appendicitis on nonenhanced helical CT scans was a dilated appendix with periappendiceal inflammatory changes. An appendix larger than 6 mm in transverse diameter was considered potentially abnormal; however, periappendiceal inflammatory changes were also required to be present for diagnosis of acute appendicitis. The presence of an appendicolith was also noted prospectively. Following completion of the examination, the CT images were immediately reviewed by a body imaging fellow or attending radiologist at the CT console.

The official radiology reports, surgical reports, and medical records of the 300 patients were reviewed (M.J.L., D.S.K., M.D.H., D.M.L.). The CT findings were compared with the surgical and pathologic findings. If surgery was not performed, then clinical follow-up was conducted on all such patients. To our knowledge, appendectomy was not performed at a later date in any of the patients who had CT scans that were interpreted as negative and who did not undergo surgery initially.

A consensus (M.J.L., D.S.K.) retrospective review was performed in those studies in which the radiology reports did not agree with the surgical and pathologic results. The original CT images from these studies were reexamined for appendiceal size and the presence of periappendiceal inflammation.


   RESULTS
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 References
 
The prospective interpretations of the nonenhanced helical CT scans in the 300 patients yielded 110 true-positive (37%) (Fig 1) and 181 true-negative diagnoses (60%). For 63 (35%) of the 181 true-negative CT interpretations, an alternative diagnosis was correctly established prospectively. A normal appendix was identified on CT scans in 139 (77%) of the 181 true-negative diagnoses, including those of patients in whom an alternative diagnosis was established at nonenhanced helical CT.



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  		Figure 1. Nonenhanced transverse helical CT scan in a 45-year-old woman with right lower quadrant pain and fever shows a dilated appendix (a) in the transverse orientation, with associated periappendiceal inflammation adjacent to the cecum (C). Note the thickened appendiceal mesocolon (arrow). The CT scan was interpreted correctly and prospectively as acute appendicitis.

 
There were four false-positive interpretations and five false-negative interpretations. In the first and second false-positive examinations, the appendix measured greater than 6 mm in transverse diameter: 7 and 10 mm. Within the 10-mm appendix, an appendicolith was also clearly evident. However, on retrospective review, periappendiceal inflammation was not present on either of the two CT scans. In the third false-positive case, the base of the appendix measured 7 mm on CT scans, with minimal periappendiceal inflammation. However, it was histologically normal. The fourth false-positive diagnosis occurred in a patient with perforated cecal diverticulitis and secondary inflammation of the appendix.

Retrospective review of two of the five false-negative CT scan interpretations showed a 9-mm dilated appendix within the pelvis of one young woman and nonvisualization of the appendix in another thin, young woman. The remaining three patients with false-negative interpretations were encountered very early in our study protocol and, in retrospect, had obviously positive diagnoses of acute appendicitis.

Identification of an appendicolith on nonenhanced helical CT scans was considered a secondary finding in acute appendicitis. Appendicitis was not diagnosed without the presence of an enlarged appendix and periappendiceal inflammation. An appendicolith was identified in 52 (47%) of the 110 true-positive diagnoses. An appendicolith was identified in one (25%) of the four false-positive diagnoses and in another true-negative diagnosis in which nonenhanced helical CT results correctly established the diagnosis of a hemorrhagic right ovarian cyst. Of the 118 true-negative findings without an alternative diagnosis, an appendicolith was present in two (2%). In both patients, the appendix was less than 6 mm in transverse diameter without periappendiceal inflammation. A total of 56 (19%) appendicoliths were identified in the 300 examinations.

In 63 (21%) of the 300 patients imaged prospectively for acute appendicitis, an alternative diagnosis was correctly established on the basis of surgical or clinical follow-up, or the additional imaging findings. Disease entities in these 63 patients included renal or ureteral calculi in 19 (30%), gynecologic disorders in 16 (25%), ascending colonic diverticulitis in eight (13%), sigmoid diverticulitis in seven (11%), small-bowel disease in five (8%), mesenteric adenitis in three (5%), and neoplasms in two (3%). Miscellaneous disorders included cholelithiasis, bladder inguinal hernia, and abscess. This analysis corresponds to an overall sensitivity of 96%, a specificity of 99%, and an accuracy of 97%. The positive predictive value was 97%, and the negative predictive value was 97%.


   DISCUSSION
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
References
 
Most patients with acute abdominal pain may be identified at triage by emergency department physicians and surgeons through careful physical examination and laboratory analysis. However, as the signs and symptoms of many acute abdominal conditions overlap, the use of imaging techniques, particularly abdominal and pelvic CT, has been shown to permit rapid and accurate diagnosis of many of these conditions (1,3,5,11).

The ability to scan the abdomen and pelvis rapidly without any bowel preparation or contrast medium has made nonenhanced helical CT the study of choice at our institutions for the evaluation of patients suspected to have acute appendicitis. Furthermore, since rectal, oral, and intravenous contrast materials are not used, other imaging studies are not precluded if no abnormality is detected on the nonenhanced CT scan. The examination is not operator-dependent and may be performed in very ill patients.

Understanding the anatomy of the ascending colon, cecum, and appendix is of great value in improving visualization of both the normal and abnormal appendix. The cecum is a highly mobile structure that can vary in position due to variations in its posterior peritoneal attachment. Furthermore, when unusually large, the cecum may extend downward, overlap the psoas muscle, and drape into the true pelvis. In these instances, identification of the appendix arising from the posteromedial base of the cecum may be difficult and may result in false-negative interpretations. Two of our five false-negative interpretations occurred in the setting of a pelvic appendix (Fig 2).



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  		Figure 2. Nonenhanced transverse helical CT scan in a 32-year-old woman with pelvic pain radiating to her right lower quadrant and fever shows a dilated appendix in the longitudinal orientation (arrow) arising from the posterior border of the cecum (C). Note that the position of the cecum is relatively low within the pelvis. The patient's pelvis was surgically explored, and acute appendicitis was found intraoperatively. This scan was incorrectly interpreted as normal.

 
Because of the highly variable position of the cecum and ascending colon, we always try to identify the fatty lips of the ileocecal valve. Careful scrutiny of the entire cecum frequently allows identification of the appendix as it arises from the posteromedial border (Fig 3). Because of this attachment, the appendix is frequently seen draped over the right external iliac artery and vein. The right common and external iliac artery and vein may be used as "vascular probes" from their origins at the bifurcation of the aorta into the femoral canal to improve detection of the overlying appendix. This usually helps to avoid the pitfall of not seeing a pelvic appendix (Fig 4).



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  		Figure 3. Nonenhanced transverse helical CT scan in a 43-year-old man with right lower quadrant pain. A dilated appendix (arrow) is shown in the longitudinal orientation, with periappendiceal inflammation consistent with acute appendicitis. The appendix arises from the posteromedial border of the cecum (C).

 


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  		Figure 4. Nonenhanced transverse helical CT scan in a 29-year-old woman with right lower quadrant pain shows a dilated appendix (x) in a longitudinal orientation, with an appendicolith (curved arrow) and mild periappendiceal inflammation (straight arrow). The appendix lies immediately anterior to the iliac artery (a) and vein (v), which are both adjacent and medial to the right psoas muscle. The scan was correctly interpreted as showing acute appendicitis. L = left.

 
The primary imaging findings of acute appendicitis at nonenhanced CT include an appendix that measures greater than 6 mm in transverse diameter and periappendiceal inflammation (1–3). Results of a recent study (12) evaluating the sensitivity and specificity of the several CT signs associated with acute appendicitis show that periappendiceal inflammation is the most sensitive sign, occurring in 100% of 93 cases of acute appendicitis. An enlarged appendix of greater than 6 mm is 93% sensitive and 100% specific for acute appendicitis in this series (12).

Additional findings on CT scans in acute appendicitis include cecal or appendiceal wall thickening, appendicoliths, and periappendiceal fluid collections (3,5,13–16). Visualization of an appendicolith may aid in identifying the appendix, although this finding is not specific for acute appendicitis (Fig 5).



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  		Figure 5. Nonenhanced transverse helical CT scan in a 24-year-old man with abdominal pain and fever shows a nondilated appendix with a small appendicolith (arrow) posterior to the cecum (C). There is no evidence of periappendiceal inflammation. Multiple fluid-filled loops of small bowel (b) are evident that suggest a diagnosis of gastroenteritis. The patient was treated successfully with medical therapy.

 
Once identified on CT images, the entire appendix should be scrutinized so that early "tip appendicitis" is not overlooked (17,18). If the appendix is noted to be enlarged, then a careful evaluation for periappendiceal inflammation, that is, stranding in the periappendiceal fat, is needed to ensure the proper diagnosis. A review of our false-positive interpretations showed that a dilated appendix (>6 mm) occurred in two of the four patients. The appendices measured 7 or 10 mm in these two patients; in one patient, an appendicolith was clearly evident. However, on retrospective review, periappendiceal inflammation was not present in either of these patients (Fig 6).



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  		Figure 6. Nonenhanced transverse helical CT scan in a 31-year-old man with pelvic pain radiating to the umbilicus shows a dilated appendix (arrow) containing an appendicolith. There is no periappendiceal inflammation. This result was prospectively interpreted as acute appendicitis; however, no evidence for acute appendicitis was identified at histologic examination.

 
Intraperitoneal fat is the intrinsic contrast medium of a nonenhanced CT examination. Identifying inflammatory changes in thin pediatric patients with little intraperitoneal fat may therefore be difficult. This was also evident in the series by Malone and colleagues (2), in which eight of 10 patients with false-negative prospective nonenhanced CT interpretations were slender with little periappendiceal or pericecal fat. Evaluation of our five false-negative interpretations shows, similarly, that three false-negative interpretations occurred in thin, young women with little intraperitoneal fat. The lack of intraperitoneal fat in these three patients resulted in obscuration of the inflammatory process in the periappendiceal fat, even though the appendix was visualized prospectively. Two false-negative examinations in our series were in patients with appendices low in the pelvis. The lack of an inflammatory process in the right lower quadrant in both of these patients resulted in misinterpretation of the findings, as the appendix was not seen prospectively.

Correctly identifying disorders that mimic acute appendicitis is as important as accurately establishing the diagnosis of acute appendicitis. We have found a high frequency (63 of 300 [21%]) of disease processes correctly diagnosed at nonenhanced helical CT that clinically simulated acute appendicitis. Many of these cases (19 of 63 [30%]) were related to renal or ureteral calculi. Fortunately, our nonenhanced helical CT protocol for renal colic is identical to that of nonenhanced helical CT for suspected acute appendicitis.

The findings of renal or ureteral calculi at nonenhanced helical CT have been well documented in the recent imaging literature (19–22). Because the entire urinary tract should be visualized from the top of the kidneys to the pelvis (1,11,20,23), we believe that in cases of suspected acute appendicitis, images should not be limited to the pelvis. This differs from a prior study in which "focused CT" of the right lower quadrant alone was used (3) (Fig 7).



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  		Figure 7a. Nonenhanced transverse helical CT scans in a 39-year-old man with right lower quadrant pain. (a) A dilated appendix (straight arrows) courses in and out of the transverse plane with periappendiceal inflammation (curved arrow), which is consistent with acute appendicitis. (b) A right ureteropelvic junction calculus (arrow) is shown. The high-attenuating material seen in the loops of small bowel is presumed to be antacid administered orally for abdominal discomfort. The lack of perinephric edema suggests that the calculus is subacute and that the patient's symptoms were related to the abnormal appendix. Acute appendicitis was found intraoperatively. This case demonstrates the importance of imaging the kidneys as part of the nonenhanced CT protocol for diagnosis of acute appendicitis.

 


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  		Figure 7b. Nonenhanced transverse helical CT scans in a 39-year-old man with right lower quadrant pain. (a) A dilated appendix (straight arrows) courses in and out of the transverse plane with periappendiceal inflammation (curved arrow), which is consistent with acute appendicitis. (b) A right ureteropelvic junction calculus (arrow) is shown. The high-attenuating material seen in the loops of small bowel is presumed to be antacid administered orally for abdominal discomfort. The lack of perinephric edema suggests that the calculus is subacute and that the patient's symptoms were related to the abnormal appendix. Acute appendicitis was found intraoperatively. This case demonstrates the importance of imaging the kidneys as part of the nonenhanced CT protocol for diagnosis of acute appendicitis.

 
Gynecologic disorders were the next most common set of conditions that mimicked acute appendicitis in our study (25%). Ovarian processes commonly mimic acute appendicitis clinically, and women of childbearing age with right-lower-quadrant pain have the greatest risk of misdiagnosis and high rates of removal of the normal appendix (35%–45%) (9,24–26). Therefore, thin women with acute right-lower-quadrant pain undergo pelvic ultrasonography (US) at our institutions because of the clinically important overlap with gynecologic disorders that mimic acute appendicitis (1,7,9,24,25,27).

Both ascending colonic and sigmoid diverticulitis were common mimickers of acute appendicitis in our study. Combined, they accounted for 15 (24%) of the alternative diagnoses established at nonenhanced helical CT. The nonenhanced CT findings were similar to contrast-enhanced CT findings, including stranding in the pericolonic fat, diverticula, and wall thickening (1,28,29). Although sigmoid diverticulitis typically manifests as left lower quadrant pain, we have noticed that a long sigmoid colon will frequently swing into the right lower quadrant of the pelvis (Fig 8). This finding was present in five of the seven patients with sigmoid diverticulitis in our study.



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  		Figure 8. Nonenhanced transverse helical CT scan of the pelvis in a 62-year-old man with right lower quadrant pain shows stranding in the perisigmoid fat (straight arrow), sigmoid wall thickening (w), sigmoid diverticula (arrowhead), and thickening of the peritoneal reflection of the sigmoid mesocolon (curved arrows), which are consistent with sigmoid diverticulitis. The patient was treated with appropriate antibiotic therapy, and his condition subsequently improved.

 
We attributed the improved sensitivity and specificity of nonenhanced helical CT for detection of suspected acute appendicitis in this series, as compared with those in earlier reports (1,2), to a variety of factors. These factors included better understanding of right lower quadrant anatomy, increased experience with the technique, improved patient triage with nonenhanced CT or US, and increased awareness of the appearance of signs suggestive of alternative diagnoses on nonenhanced CT scans.

We do not recommend nonenhanced helical CT for the diagnosis of all conditions, however; the interpreter must be aware of the broad range of abnormalities that may mimic a very common disorder. The value of a true-negative study is difficult to determine; however, accurately diagnosing those conditions that can mimic acute appendicitis, a very common disorder, may help reduce the number of unnecessary appendectomies.

Recently, the use of only rectal contrast material for the diagnosis of appendicitis has been advocated (4); however, up to 15%–20% of normal appendices do not fill during fluoroscopic barium enemas (30), and in some patients the appendix may partially fill proximal to the site of appendiceal obstruction (30–32). As with other authors, we have not found it necessary to administer rectal contrast material to achieve excellent results (23).

In conclusion, we consider nonenhanced helical CT to be the initial study of choice for confirmation of suspected appendicitis in adult patients with a normal or obese body habitus. US remains the primary imaging modality for pediatric patients, pregnant patients, and very thin patients of either sex with suspected acute appendicitis. Use of this rapid, non–operator-dependent and, in our experience, highly accurate examination may decrease delays in appropriate medical or surgical therapy.


   Footnotes
 
The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Army, Department of Defense, or the United States Government.

Author contributions: Guarantor of integrity of entire study, M.J.L.; study concepts, M.J.L., D.S.K., R.B.J., R.E.M.; study design, M.J.L., D.S.K.; definition of intellectual content, M.J.L., D.S.K., R.E.M., R.B.J.; literature research, M.J.L., D.S.K.; clinical studies, M.J.L., D.S.K., R.B.J.; data acquisition, M.J.L., D.M.L., M.D.H., D.S.K.; data analysis, M.J.L.; manuscript preparation, M.J.L., D.S.K., R.E.M.; manuscript editing and review, M.J.L., D.S.K., R.E.M., R.B.J.


   References
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

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  20. Katz DS, Lane MJ, Sommer FG. Unenhanced helical CT of ureteral stones: incidence of associated urinary tract findings. AJR 1996; 166:1319-1322.[Abstract/Free Full Text]
  21. Smith RC, Verga M, Dalrymple NC, McCarthy S, Rosenfield AT. Acute ureteral obstruction: value of secondary signs on helical unenhanced CT. AJR 1996; 167:1109-1113.[Abstract/Free Full Text]
  22. Kawashima A, Sandler CM, Boridy IC, Takahashi N, Benson GS, Goldman SM. Unenhanced helical CT of ureterolithiasis: value of the tissue rim sign. AJR 1997; 168:997-1000.[Abstract/Free Full Text]
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Comparison of colonic transit between polyethylene glycol and water as oral contrast vehicles in the CT evaluation of acute appendicitis.
Am. J. Roentgenol., November 1, 2006; 187(5): 1188 - 1191.
[Abstract] [Full Text] [PDF]

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S. Ganguli, V. Raptopoulos, F. Komlos, B. Siewert, and J. B. Kruskal
Right Lower Quadrant Pain: Value of the Nonvisualized Appendix in Patients at Multidetector CT
Radiology, October 1, 2006; 241(1): 175 - 180.
[Abstract] [Full Text] [PDF]

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 Am. J. Roentgenol.Home page
J. E. Jacobs
CT and Sonography for Suspected Acute Appendicitis: A Commentary.
Am. J. Roentgenol., April 1, 2006; 186(4): 1094 - 1096.
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A. B. MacKersie, M. J. Lane, R. T. Gerhardt, H. A. Claypool, S. Keenan, D. S. Katz, and J. E. Tucker
Nontraumatic Acute Abdominal Pain: Unenhanced Helical CT Compared with Three-View Acute Abdominal Series
Radiology, October 1, 2005; 237(1): 114 - 122.
[Abstract] [Full Text] [PDF]

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N. Pinto Leite, J. M. Pereira, R. Cunha, P. Pinto, and C. Sirlin
CT Evaluation of Appendicitis and Its Complications: Imaging Techniques and Key Diagnostic Findings
Am. J. Roentgenol., August 1, 2005; 185(2): 406 - 417.
[Abstract] [Full Text] [PDF]

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C. Keyzer, M. Zalcman, V. De Maertelaer, E. Coppens, M.-A. Bali, P. A. Gevenois, and D. Van Gansbeke
Comparison of US and Unenhanced Multi-Detector Row CT in Patients Suspected of having Acute Appendicitis
Radiology, August 1, 2005; 236(2): 527 - 534.
[Abstract] [Full Text] [PDF]

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C. P. Daly, R. H. Cohan, I. R. Francis, E. M. Caoili, J. H. Ellis, and B. Nan
Incidence of Acute Appendicitis in Patients with Equivocal CT Findings
Am. J. Roentgenol., June 1, 2005; 184(6): 1813 - 1820.
[Abstract] [Full Text] [PDF]

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E. K. Paulson, J. P. Harris, T. A. Jaffe, P. A. Haugan, and R. C. Nelson
Acute Appendicitis: Added Diagnostic Value of Coronal Reformations from Isotropic Voxels at Multi-Detector Row CT
Radiology, June 1, 2005; 235(3): 879 - 885.
[Abstract] [Full Text] [PDF]

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J. Yu, A. S. Fulcher, M. A. Turner, and R. A. Halvorsen
Helical CT Evaluation of Acute Right Lower Quadrant Pain: Part I, Common Mimics of Appendicitis
Am. J. Roentgenol., April 1, 2005; 184(4): 1136 - 1142.
[Abstract] [Full Text] [PDF]

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T. A. Foley, F. Earnest IV, M. A. Nathan, D. M. Hough, H. J. Schiller, and T. L. Hoskin
Differentiation of Nonperforated from Perforated Appendicitis: Accuracy of CT Diagnosis and Relationship of CT Findings to Length of Hospital Stay
Radiology, April 1, 2005; 235(1): 89 - 96.
[Abstract] [Full Text] [PDF]

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T. Terasawa, C. C. Blackmore, S. Bent, and R. J. Kohlwes
Systematic Review: Computed Tomography and Ultrasonography To Detect Acute Appendicitis in Adults and Adolescents
Ann Intern Med, October 5, 2004; 141(7): 537 - 546.
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C. M. Rucker, C. O. Menias, and S. Bhalla
Mimics of Renal Colic: Alternative Diagnoses at Unenhanced Helical CT
RadioGraphics, October 1, 2004; 24(suppl_1): S11 - S28.
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D. S. Katz, M. Jain, M. J. Lane, E. M. Meiner, S. Bhalla, C. O. Menias, and C. M. Rucker
Invited Commentary * Authors' Response
RadioGraphics, October 1, 2004; 24(suppl_1): S28 - S33.
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C. Keyzer, D. Tack, V. de Maertelaer, P. Bohy, P. A. Gevenois, and D. Van Gansbeke
Acute Appendicitis: Comparison of Low-Dose and Standard-Dose Unenhanced Multi-Detector Row CT
Radiology, July 1, 2004; 232(1): 164 - 172.
[Abstract] [Full Text] [PDF]

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J. M. Pereira, C. B. Sirlin, P. S. Pinto, R. B. Jeffrey, D. L. Stella, and G. Casola
Disproportionate Fat Stranding: A Helpful CT Sign in Patients with Acute Abdominal Pain
RadioGraphics, May 1, 2004; 24(3): 703 - 715.
[Abstract] [Full Text] [PDF]

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L. Neumayer and A. Kennedy
Imaging in Appendicitis: A Review With Special Emphasis on the Treatment of Women
Obstet. Gynecol., December 1, 2003; 102(6): 1404 - 1409.
[Abstract] [Full Text] [PDF]

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P. Poortman, P. N. M. Lohle, C. M. C. Schoemaker, H. J. M. Oostvogel, H. J. L. J. M. Teepen, K. A. H. Zwinderman, and J. F. Hamming
Comparison of CT and Sonography in the Diagnosis of Acute Appendicitis: A Blinded Prospective Study
Am. J. Roentgenol., November 1, 2003; 181(5): 1355 - 1359.
[Abstract] [Full Text] [PDF]

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V. Raptopoulos, G. Katsou, M. P. Rosen, B. Siewert, S. N. Goldberg, and J. B. Kruskal
Acute Appendicitis: Effect of Increased Use of CT on Selecting Patients Earlier
Radiology, February 1, 2003; 226(2): 521 - 526.
[Abstract] [Full Text] [PDF]

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E. K. Paulson, M. F. Kalady, and T. N. Pappas
Suspected Appendicitis
N. Engl. J. Med., January 16, 2003; 348(3): 236 - 242.
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O. Benjaminov, M. Atri, P. Hamilton, and D. Rappaport
Frequency of Visualization and Thickness of Normal Appendix at Nonenhanced Helical CT
Radiology, November 1, 2002; 225(2): 400 - 406.
[Abstract] [Full Text] [PDF]

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S. E. Bendeck, M. Nino-Murcia, G. J. Berry, and R. B. Jeffrey Jr
Imaging for Suspected Appendicitis: Negative Appendectomy and Perforation Rates
Radiology, October 1, 2002; 225(1): 131 - 136.
[Abstract] [Full Text] [PDF]

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P. J. Pickhardt, A. D. Levy, C. A. Rohrmann Jr, and A. I. Kende
Primary Neoplasms of the Appendix Manifesting as Acute Appendicitis: CT Findings with Pathologic Comparison
Radiology, September 1, 2002; 224(3): 775 - 781.
[Abstract] [Full Text] [PDF]

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S. S. Raman, D. S. K. Lu, B. M. Kadell, D. J. Vodopich, J. Sayre, and H. Cryer
Accuracy of Nonfocused Helical CT for the Diagnosis of Acute Appendicitis: A 5-Year Review
Am. J. Roentgenol., June 1, 2002; 178(6): 1319 - 1325.
[Abstract] [Full Text] [PDF]

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J.-H. Lee, Y. K. Jeong, J. C. Hwang, S. Y. Ham, and S.-O. Yang
Graded Compression Sonography with Adjuvant Use of a Posterior Manual Compression Technique in the Sonographic Diagnosis of Acute Appendicitis
Am. J. Roentgenol., April 1, 2002; 178(4): 863 - 868.
[Abstract] [Full Text] [PDF]

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N. R. Fefferman, K. J. Roche, L. P. Pinkney, M. M. Ambrosino, and N. B. Genieser
Suspected Appendicitis in Children: Focused CT