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Published online before print March 18, 2004, 10.1148/radiol.2312030240
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(Radiology 2004;231:427-433.)
© RSNA, 2004

Pediatric Imaging

Suspected Appendicitis in Children: Diagnosis with Contrast-enhanced versus Nonenhanced Helical CT1

Sylvie Kaiser, MD, Thröstur Finnbogason, MD, Håkan K. Jorulf, MD, PhD, Erik Söderman, PhD and Björn Frenckner, MD, PhD

1 From the Departments of Pediatric Radiology (S.K., T.F., H.K.J.) and Pediatric Surgery (B.F.), Astrid Lindgren Children’s Hospital, Karolinska Hospital, SE-171 76 Stockholm, Sweden, and Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden (E.S.). Received February 20, 2003; revision requested April 29; final revision received October 8; accepted November 12. Supported by grants from Crown Princess Lovisa’s Association for Children’s Health Care and the Axel Tielman Foundation. Address correspondence to S.K. (e-mail: sylvie.kaiser@ks.se).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To compare the diagnostic accuracy of limited-area (lower abdominal) nonenhanced helical computed tomography (CT), intravenous contrast material–enhanced helical CT of the entire abdomen, and the combination of both.

MATERIALS AND METHODS: Three hundred six children suspected of having appendicitis, who were previously included in a prospective study, underwent limited-area nonenhanced helical CT of the lower abdomen and contrast-enhanced CT of the entire abdomen. No oral or rectal contrast material was administered. The CT scans were retrospectively reviewed by three independent readers both separately and together. The readers were blinded to all clinical information and to the results of previous ultrasonographic and CT examinations. Final diagnoses were established on the basis of surgical, histopathologic, or clinical follow-up findings. The Pearson {chi}2 test was performed to compare values between groups. The Student two-sample t test was performed to determine statistically significant differences in age and sex.

RESULTS: One hundred twenty-nine patients (42%) had appendicitis. Readers diagnosed appendicitis with 66% pooled sensitivity and 96% pooled specificity with limited-area nonenhanced CT. With contrast-enhanced CT of the entire abdomen, appendicitis was diagnosed with 90% pooled sensitivity and 94% pooled specificity. With both sequences together, readers diagnosed appendicitis with 90% pooled sensitivity and 94% pooled specificity. The difference between the sensitivity of limited-area nonenhanced CT and that of contrast-enhanced CT was statistically significant (P < .001).

CONCLUSION: Sensitivity of helical CT for suspected appendicitis in children improved significantly with abdominal contrast-enhanced CT compared with limited-area nonenhanced CT. No further improvement in sensitivity was achieved with the combination of both sequences in comparison to that with contrast-enhanced CT alone.

© RSNA, 2004

Index terms: Appendicitis, 751.291 • Appendix, CT, 751.12112, 751.12115 • Children, gastrointestinal tract, 751.291 • Computed tomography (CT), in infants and children, 751.12112, 751.12115 • Infants, gastrointestinal tract, 751.291


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Helical computed tomography (CT) has been reported to be a highly sensitive and specific means of diagnosis of acute appendicitis (1). The staff of several institutions have now accepted helical CT as the method of first choice because of its advantages over ultrasonography (US), including less operator dependence, more confident visualization of the appendix, and better delineation of the extent of phlegmon and abscess in complicated appendicitis (1). Disadvantages of CT include the higher cost; potential risks of contrast media; and ionizing radiation exposure, which is especially critical in children (2). However, a minority of studies are focused on children (1). Furthermore, a variety of techniques are being used at different institutions, and there is considerable controversy in the literature regarding the use of oral, rectal, or intravenous contrast agents and the question of whether or not the area scanned should be limited (1,3).

At our institution, US remains the imaging modality of first choice in the diagnosis of appendicitis because it is noninvasive, uses no ionizing radiation, and requires no patient preparation. In our experience, a positive US scan greatly helps rule in the diagnosis of appendicitis. A negative US scan, however, does not exclude appendicitis unless a normal appendix is confidently visualized; in inconclusive cases, CT is frequently added to improve diagnostic accuracy. This management routine is supported by the results of our previous prospective randomized study (4), which included 600 patients who were allocated randomly to undergo US only (283 patients) or US and abdominal CT (317 patients). Until recently, the CT protocol used in that study has been unchanged since its introduction at our institution in 1997. That protocol included limited-area (lower abdominal) nonenhanced CT followed by contrast material–enhanced CT of the entire abdomen. No oral or rectal contrast material is administered. However, limitation of the radiation dose is desirable in the imaging of children, and thus there was a need for an updated CT protocol that included only one scanning procedure.

The purpose of our study was to compare the diagnostic accuracy of limited-area nonenhanced helical CT, contrast-enhanced helical CT of the entire abdomen, and the combination of both.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Study Population and Imaging
The abdominal CT scans of 306 pediatric patients who were clinically suspected of having appendicitis, and who were included in a previous prospective randomized study (4), formed our study population. Eleven of the original 317 patients were excluded because of technical difficulties with both CT sequences in the retrospective interpretations when the picture archiving and communication system software was upgraded. Hence, the population for the current study comprised 306 patients (mean age, 10.6 years; age range, 2–15 years). There were 154 boys (mean age, 10.3 years; age range, 2–15 years) and 152 girls (mean age, 10.8 years; age range, 4–15 years). The age difference between the two sexes was not statistically significant (two-sample t test, t = 1.64; 304 degrees of freedom; P = .103). The study was approved by the local ethics committee. Informed consent had been obtained from each child’s parents for the prospective randomized study but was not required for the retrospective review in the current study.

Patients in the current study underwent nonenhanced helical CT of the lower abdomen followed by contrast-enhanced helical CT of the entire abdomen. The latter examination was performed with a nonionic contrast medium: iohexol (Omnipaque [300 mg of iodine per milliliter]; Nycomed Amersham, Oslo, Norway) in 27 patients and iodixanol (Visipaque [270 mg of iodine per milliliter]; Nycomed Amersham) in 279 patients. The two contrast media have equivalent pharmacologic and toxicologic properties (5). The injected dose was 2 mL per kilogram of body weight, with an upper limit of 100 mL. No oral or rectal contrast material was administered. All examinations were performed with a single–detector row CT scanner (CT HiSpeed Advantage; GE Medical Systems, Milwaukee, Wis) (ie, not a dual– or multi–detector row scanner). Helical scanning was performed with 5-mm collimation, 10 mm/sec table speed, and 5-mm reconstruction in patients younger than 6 years and with 7-mm collimation, 14 mm/sec table speed, and 7-mm reconstruction in patients 6 years of age or older. For children aged 10–12 years, the calculated effective dose was 2.3 mSv for limited-area nonenhanced CT and was 5.2 mSv for contrast-enhanced CT of the entire abdomen. Images were stored in a digital picture archiving and communication system (PACS IDS 4–5; Sectra, Linköping, Sweden).

Image Interpretation
During the 9 months from February through October 2002, the CT scans were retrospectively reviewed on computer monitors by three pediatric radiologists (S.K., T.F., H.K.J.), each with more than 12 years of experience in pediatric radiology, including CT, working independently. The CT scans were divided into three groups, which were evaluated in a different order by the three readers: group A, all limited-area nonenhanced CT scans; group B, all contrast-enhanced CT scans; and group C, all nonenhanced and all contrast-enhanced CT scans together. Readers 1–3 evaluated the groups of scans in the following order: reader 1, groups B, C, A; reader 2, groups C, A, B; and reader 3, groups A, B, C. The scans appeared in different order in groups A–C to avoid any recall bias. The CT diagnosis of appendicitis was based on visualization of an abscess or of an appendix with maximal diameter of more than 6 mm, mural thickness of l2 mm or more, and possible mural enhancement, with or without pericecal inflammation. If the appendix was not definitively identified, the readers diagnosed appendicitis if an appendicolith associated with pericecal inflammation or abscess was present. The readers stated whether appendicitis was present or not and estimated their level of confidence in this statement on a scale from 0% to 100%. The diagnosis and the level of confidence were estimated separately. In groups B and C, the entire abdomen was evaluated for alternative and additional diagnoses. The readers were blinded to all clinical information, including the final diagnoses and the results of previous US and CT examinations.

Final Diagnoses
The final diagnoses were determined at surgery and histopathologic examination in the patients who underwent laparotomy (n = 130). The patients treated without surgery (n = 176) were followed up with a questionnaire that was sent to the child’s parents 6 months after admission to track any possible treatment elsewhere for appendicitis and, hence, any false-negative diagnoses (4). The questionnaire was completed by the parents of 166 (94%) of the 176 patients who did not undergo surgery. The medical records of all patients were reviewed by one author (S.K.).

Statistical Analysis
Individual and pooled sensitivity and specificity were calculated for the diagnosis of appendicitis for groups A–C. The Pearson {chi}2 test was performed to compare the values between groups. A P value of .05 or less was considered to indicate a statistically significant difference. Receiver operating characteristic (ROC) curves were calculated by group for each reader.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Final Diagnoses
Of the 306 patients, 129 (42%) had a final diagnosis of appendicitis. Of these 129 patients, 124 underwent appendectomy and four were treated conservatively with antibiotics for an appendiceal abscess. The remaining patient had CT scans that were interpreted as negative for appendicitis by all three readers. The patient’s condition improved initially after discharge but did not resolve completely, and the patient was treated with drainage for an appendiceal abscess 2 weeks later (Table 1). This case was considered to be false-negative when statistical calculations were performed.


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  		TABLE 1. Patients with Highest Frequency of Incorrect CT Interpretations

 
One hundred seventy-seven patients did not have appendicitis. Laparotomy was performed in six of these patients. Three of the six patients were treated for alternative diagnoses (ovarian torsion, mechanical ileus, and pancreatitis caused by superior mesenteric artery syndrome), all of which had been diagnosed at preoperative radiologic imaging. The other three patients had negative findings at appendectomy (the decision to perform surgery was based on clinical findings in all of them). In two of these three patients, the CT findings were interpreted as negative for appendicitis by all three readers with all groups of scans. In the remaining patient, an appendix with a diameter of 8–9 mm and an appendicolith were identified by all three readers, and they all stated that appendicitis was present with all groups of scans. Findings at histopathologic examination in this case revealed lymphoid hyperplasia but no inflammation (Table 1). Results in this case were considered false-positive when statistical calculations were performed.

The majority (n = 172) of the 176 patients treated without surgery had CT findings that were negative for appendicitis; the final diagnoses included nonspecific abdominal pain (n = 99), mesenteric lymphadenitis (n = 50), gastroenteritis (n = 13), urinary tract infection or calculi (n = 4), ovarian cyst (n = 2), pneumonia (n = 2), and cholelithiasis (n = 1). The remaining patient was treated for an appendiceal abscess 2 weeks after discharge.

Image Interpretation
The readers diagnosed appendicitis with pooled sensitivity of 66% (range, 57%–72%) with limited-area nonenhanced helical CT scans (group A). The sensitivity improved with contrast-enhanced abdominal helical CT scans (group B) to 90% (range, 83%–96%). The combination of both sets of images (group C) did not further improve the sensitivity (90%; range, 84%–98%). The specificity with group A was 96% (range, 94%–97%), and that with groups B and C was 94% (range, 92%–96% and 91%–98%, respectively). The individual and pooled sensitivity and specificity values are listed in Table 2. The difference between the sensitivity values, for each reader individually and for pooled results, between groups A and B was statistically significant as was the difference between groups A and C (P < .001), while the difference between groups B and C was not significant (P = .719). No statistical significance was achieved for the difference between specificity values for each reader individually or for pooled results (P = .379). ROC curves calculated for each group for each reader are presented in Figure 1. Clarifying data for those calculations are listed in Table 3.


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  		TABLE 2. Evaluation of Appendicitis with Helical CT Scans in Groups A-C

 


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  		Figure 1a. Line graphs depict areas under the ROC curves for readers 1-3 with helical CT scans in groups A-C. (a) Group A (limited-area nonenhanced scans). Mean area under the ROC curve for reader 1 was 0.872 ± 0.022 (standard error), for reader 2 was 0.920 ± 0.017, and for reader 3 was 0.856 ± 0.023. (b) Group B (abdominal contrast-enhanced scans. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.968 ± 0.011, and for reader 3 was 0.947 ± 0.012. (c) Group A and group B scans together. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.963 ± 0.013, and for reader 3 was 0.942 ± 0.014.

 


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  		Figure 1b. Line graphs depict areas under the ROC curves for readers 1-3 with helical CT scans in groups A-C. (a) Group A (limited-area nonenhanced scans). Mean area under the ROC curve for reader 1 was 0.872 ± 0.022 (standard error), for reader 2 was 0.920 ± 0.017, and for reader 3 was 0.856 ± 0.023. (b) Group B (abdominal contrast-enhanced scans. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.968 ± 0.011, and for reader 3 was 0.947 ± 0.012. (c) Group A and group B scans together. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.963 ± 0.013, and for reader 3 was 0.942 ± 0.014.

 


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  		Figure 1c. Line graphs depict areas under the ROC curves for readers 1-3 with helical CT scans in groups A-C. (a) Group A (limited-area nonenhanced scans). Mean area under the ROC curve for reader 1 was 0.872 ± 0.022 (standard error), for reader 2 was 0.920 ± 0.017, and for reader 3 was 0.856 ± 0.023. (b) Group B (abdominal contrast-enhanced scans. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.968 ± 0.011, and for reader 3 was 0.947 ± 0.012. (c) Group A and group B scans together. Mean area under the ROC curve for reader 1 was 0.981 ± 0.007, for reader 2 was 0.963 ± 0.013, and for reader 3 was 0.942 ± 0.014.

 

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  		TABLE 3. Evaluation of Appendicitis: Comparison of Area under ROC Curve for Readers 1-3 with Helical CT Scans in Groups A-C.

 
The appendix (both normal and abnormal) was identified by readers 1, 2, and 3, respectively, in 99, 84, and 72 of 306 patients with the scans in group A and in 160, 137, and 130 of 306 patients with the scans in groups B and C (Fig 2). Mean appendiceal diameter was 10.3 mm (range, 6–19 mm) in patients with a final diagnosis of appendicitis and was 5.5 mm (range, 2–9 mm) in patients without appendicitis.



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  		Figure 2a. Transverse helical CT scans in a 9-year-old girl with appendicitis. (a) Group A scan (nonenhanced) shows that the appendix is not clearly identifiable. (b) Group B scan (contrast enhanced) obtained at the same level as a shows thickening and contrast enhancement of inflamed appendiceal wall (arrow).

 


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  		Figure 2b. Transverse helical CT scans in a 9-year-old girl with appendicitis. (a) Group A scan (nonenhanced) shows that the appendix is not clearly identifiable. (b) Group B scan (contrast enhanced) obtained at the same level as a shows thickening and contrast enhancement of inflamed appendiceal wall (arrow).

 
Appendicoliths were detected by readers 1, 2, and 3, respectively, in 84, 90, and 54 of 306 patients with group A CT scans; in 82, 78, and 63 of 306 patients with group B scans; and in 87, 83, and 70 of 306 patients with group C scans.

The estimated level of confidence for the diagnosis of appendicitis was higher than 50% for all interpretations by the three readers. All readers estimated a higher level of confidence with groups B and C scans (contrast enhanced) than with group A scans (nonenhanced). The readers estimated a higher level of confidence in their diagnosis when appendicitis was present than when it was not. The difference was most evident with group A scans (Fig 3). In cases when a clearly normal appendix was identified, the level of confidence was approximately as high as that in cases when appendicitis was present. The readers estimated a lower level of confidence when the interpretation was incorrect compared with the final diagnosis whether or not appendicitis was estimated to be present. Patients with the highest frequency of incorrect CT interpretations compared with the final diagnoses are listed in Table 1.



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  		Figure 3. Mean level of confidence estimated by readers 1-3 with CT scans in groups A-C. Hatched bars = appendicitis stated as not present; gray bars = appendicitis stated as present. Error bars represent plus or minus 1 SD. Readers estimated higher level of confidence with contrast-enhanced CT scans. With nonenhanced CT scans, the level of confidence was higher when they stated that appendicitis was present.

 
Alternative and additional diagnoses established by the three readers include hydronephrosis (n = 3), pyelonephritis (n = 2), urinary tract calculi (n = 1), liver hemangioma (n = 1), cholelithiasis (n = 1), splenomegaly (n = 2), splenic cyst (n = 1), pancreatitis caused by superior mesenteric artery syndrome (n = 1), ileus (n = 1), ovarian cyst or torsion (n = 3), and basilar pneumonia (n = 1 [lung bases were included in the abdominal contrast-enhanced CT scan in this patient]). In addition to these diagnoses, enteritis or mesenteric lymphadenitis was suspected in 14 patients.

The accuracy of alternative diagnoses was not assessed because of the lack of a consistent reference standard. Nevertheless, alternative diagnoses were determined to a greater extent by all three readers with the helical CT scans in groups B and C (ie, when the entire abdomen was included in the scanning field of view and contrast enhancement was used).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Helical CT has become a valuable means of evaluating suspected appendicitis and is now accepted by several institutions as the method of first choice in the adult and pediatric populations (6–8). No definitive CT technique has been established for the evaluation of appendicitis in children, however, and various protocols have been described. In routine imaging, different techniques are sometimes used at the same diagnostic center, as reported in a descriptive article from a large teaching hospital (8). The major subjects of discussion are the use of and mode of administration of contrast material and possible limitation of the scanning field with regard to reduction of the radiation dose. The need for further studies in which different helical CT techniques are compared has been postulated previously (8,9).

Rectal contrast media are recommended in children by several authors (10,11) to improve identification of the cecum and appendix. Others, however, believe that rectally administered contrast material is unnecessary and the procedure is too time-consuming because the colon and cecum in children are usually clearly identifiable at CT on the basis of location and contents (12). Our results support the latter position.

The use of intravenous contrast agents in appendiceal CT in children has been recommended by several authors (8,9,13,14), although no comparison between contrast-enhanced and nonenhanced CT was performed. To our knowledge, the only previously published comparison of this kind is a study by Jacobs et al (15), which demonstrated a significant improvement in diagnostic accuracy with use of nonfocused contrast-enhanced CT compared with focused nonenhanced CT in adolescent and adult patients. Their results are supported by those in the present study, which demonstrate significantly improved sensitivity with intravenous contrast material and inclusion of the entire abdomen in the scanning field. The smaller volume of intraperitoneal fat that is generally seen in children, especially those younger than 10 years, has been shown to decrease the rate of identification of a normal appendix (16). We believe that this finding is also valid in cases of appendicitis, but to compensate for it, we suggest use of intravenous contrast agents. Nonionic intravenous contrast agents are well tolerated in children, and adverse reactions occur less frequently in children than in adults (17,18).

The reduced dose of ionizing radiation has been postulated as a major reason for limitation of the scanning field. Children are at greater risk from ionizing radiation than are adults (2) because they have a higher lifetime risk of developing fatal cancer as a result of their longer life expectancies and because of the increased radiation sensitivity of developing tissues; therefore, reduced radiation dose is desirable. It has been shown, however, that limitation of the scanning field may result in failure to include the appendix in the CT scan and may adversely affect the reader’s ability to diagnose alternative conditions (10,15). As previously postulated, CT should be performed with the lowest dose that allows the radiologist to provide the necessary diagnostic information (1,2). Nevertheless, the greatest possible decrease in risk from ionizing radiation at CT is a result of an unnecessary study not being performing.

The results of our present study do not support any further use of two CT sequences in the evaluation of suspected appendicitis. Since nonenhanced helical CT of the lower abdomen had a significantly lower sensitivity than did contrast-enhanced helical CT of the entire abdomen and since the combination of scans obtained with both sequences did not yield any further improvement in sensitivity in comparison to that with contrast-enhanced CT scans alone, limited-area nonenhanced CT has recently been excluded from our routine protocol. The original protocol was designed to improve detection of appendicoliths; however, our results do not confirm any significant improvement. The current routine CT protocol for evaluation of suspected appendicitis at our institution includes only contrast-enhanced helical CT of the entire abdomen. With the current protocol, the total radiation dose has been reduced by approximately 31%, and exposure to the gonads has been reduced by approximately 50% because the limited-area scan has been excluded (the radiation dose is equal in both the limited-area and the nonlimited scan).

In the present study, the entire abdomen was evaluated when it was included in the scanning field. Consequently, alternative and additional diagnoses were established to a greater extent with the CT scans in groups B and C than with those in group A. Nevertheless, the total number of pathologic conditions identified in the upper abdomen in this study was low. In the study by Kamel et al (19), abnormalities in the upper abdomen were detected in seven of 100 adult patients, while several other authors (11,12,20) had the same experience that we did with patient populations comparable to ours. Comparison is difficult between the pediatric patients in our study and the adult patients in the study of Kamel et al. There is a need for further studies regarding extension of the scanning field.

There are several possible explanations for the most frequent incorrect CT interpretations in the patients listed in Table 1, including well-known difficulties such as perforated appendicitis and borderline appendix diameters. Appendiceal diameter was 8–9 mm in patients 13–15 (Table 1), and an appendicolith was present in the last two patients, which explains why all readers stated that appendicitis was present in these patients with the CT scans in all groups. Only patient 15 underwent appendectomy, and lymphoid hyperplasia was revealed at histopathologic examination. This condition has previously been reported as a possible cause of a sonographically abnormal appendix (21). Lymphoid hyperplasia may have also been present in patients 13 and 14, but the exact cause of the increased diameter of the appendix remains unknown because surgery was not performed. These cases may also represent spontaneously resolving appendicitis (22,23).

The results of our previous prospective randomized study (4) yielded sensitivity of 97% and specificity of 93% with the combination of limited-area nonenhanced CT and contrast-enhanced CT of the entire abdomen in the same patients included in this retrospective study. Consequently, sensitivity values achieved by the three readers in the present study were lower than those achieved in the first study, which were used for clinical management, and were also lower than those reported in other studies (6,7,10). On the other hand, other authors (24) report even lower sensitivity values than those achieved in our present study. Specificity values were higher in the present study. A possible reason for the lower sensitivity in the present study is the total lack of access to clinical information and results of previous US examinations. Still, the sensitivity and specificity values achieved in the current study are high enough to identify CT as useful for long-distance consultations between radiologists without access to clinical data or the results of a US examination (eg, by using an interhospital teleradiology system).

A limitation of the current study is that the retrospective design creates an artificial situation. This may affect the interpretations and may contribute to the difference between the results of our prospective and retrospective studies. Another possible limitation is the fact that no consensus interpretation was performed to verify that the same structure was identified as the appendix by each reader. However, this lack of consensus simulates the independent interpretations that occur in a routine clinical practice.

Results of the current study demonstrate that contrast-enhanced helical CT of the entire abdomen significantly improved the readers’ ability to diagnose acute appendicitis in comparison to that with limited-area nonenhanced helical CT. The use of CT scans obtained with both sequences together did not yield any further improvement in sensitivity in comparison to that with contrast-enhanced CT scans alone. On the basis of the results of the current study, we conclude that helical CT for the diagnosis of appendicitis in children should be performed with intravenous contrast material. Further studies are needed to evaluate whether or not the area to be scanned should be limited.


   FOOTNOTES
 
See also the editorial by Taylor in this issue.

Abbreviation: ROC = receiver operating characteristic

Author contributions: Guarantors of integrity of entire study, all authors; study concepts and design, all authors; literature research, S.K.; clinical studies, S.K., T.F., H.K.J.; data acquisition, S.K., T.F., H.K.J.; data analysis/interpretation, all authors; statistical analysis, E.S., S.K.; manuscript preparation, S.K.; manuscript definition of intellectual content, editing, and revision/review, S.K., H.K.J., B.F.; manuscript final version approval, all authors


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Guillerman RP, Brody AS, Kraus SJ. Evidence-based guidelines for pediatric imaging: the example of the child with possible appendicitis. Pediatr Ann 2002; 31:629-640.[Medline]
  2. Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001; 176:289-296.[Abstract/Free Full Text]
  3. 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]
  4. 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]
  5. Lee FT, Jr, Caroline DF, Thornbury JR, et al. A randomized comparison of iodixanol and iohexol in adult body computed tomography scanning. Acad Radiol 1996; 3(suppl 3):S500-S506.
  6. Garcia Pena BM, Mandl KD, Kraus S, et al. Ultrasonography and limited computed tomography in the diagnosis and management of appendicitis in children. JAMA 1999; 282:1041-1046.[Abstract/Free Full Text]
  7. Sivit CJ, Applegate KE, Stallion A, et al. Imaging evaluation of suspected appendicitis in a pediatric population: effectiveness of sonography versus CT. AJR Am J Roentgenol 2000; 175:977-980.[Abstract/Free Full Text]
  8. Callahan MJ, Rodriguez DP, Taylor GA. CT of appendicitis in children. Radiology 2002; 224:325-332.[Abstract/Free Full Text]
  9. Birnbaum BA, Wilson SR. Appendicitis at the millennium. Radiology 2000; 215:337-348.[Abstract/Free Full Text]
  10. Rao PM, Rhea JT, Novelline RA, Mostafavi AA, Lawrason JN, McCabe CJ. Helical CT combined with contrast material administered through the colon for imaging of suspected appendicitis. AJR Am J Roentgenol 1997; 169:1275-1280.[Abstract/Free Full Text]
  11. Mullins ME, Kircher MF, Ryan DP, et al. Evaluation of suspected appendicitis in children using limited helical CT and colonic contrast material. AJR Am J Roentgenol 2001; 176:37-41.[Abstract/Free Full Text]
  12. Lowe LH, Penney MW, Stein SM, et al. Unenhanced limited CT of the abdomen in the diagnosis of appendicitis in children: comparison with sonography. AJR Am J Roentgenol 2001; 176:31-35.[Abstract/Free Full Text]
  13. Friedland JA, Siegel MJ. CT appearance of acute appendicitis in childhood. AJR Am J Roentgenol 1997; 168:439-442.[Free Full Text]
  14. Federle MP. Focused appendix CT technique: a commentary. Radiology 1997; 202:20-21.[Free Full Text]
  15. 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]
  16. Grayson DE, Wettlaufer JR, Dalrymple NC, Keesling CA. Appendiceal CT in pediatric patients: relationship of visualization to amount of peritoneal fat. AJR Am J Roentgenol 2001; 176:497-500.[Abstract/Free Full Text]
  17. Katayama H, Yamaguchi K, Kozuka T, Takashima T, Seez P, Matsuura K. Adverse reactions to ionic and non-ionic contrast media. Radiology 1990; 175:621-628.[Abstract/Free Full Text]
  18. Cohen MD, Herman E, Herron D, White SJ, Smith JA. Comparison of intravenous contrast agents for CT studies in children. Acta Radiol 1992; 33:592-595.[Medline]
  19. Kamel IR, Goldberg NS, Keogan MT, Rosen MP, Raptopoulos V. Right lower quadrant pain and suspected appendicitis: nonfocused appendiceal CT—review of 100 cases. Radiology 2000; 217:159-163.[Abstract/Free Full Text]
  20. Fefferman NR, Roche KJ, Pinkney LP, Ambrosino MM, Genieser NB. Suspected appendicitis in children: focused CT technique for evaluation. Radiology 2001; 220:691-695.[Abstract/Free Full Text]
  21. Hahn HB, Hoepner FU, Kalle T, et al. Sonography of acute appendicitis in children: a 7 years experience. Pediatr Radiol 1998; 28:147-151.[CrossRef][Medline]
  22. Vignault F, Filiatrault D, Brandt ML, Garel L, Grignon A, Ouimet A. Acute appendicitis in children: evaluation with US. Radiology 1990; 176:501-504.[Abstract/Free Full Text]
  23. Migraine S, Atri M, Bret PM, Lough JO, Hinchey JE. Spontaneously resolving appendicitis: clinical and sonographical documentation. Radiology 1997; 205:55-58.[Abstract/Free Full Text]
  24. Karakas SP, Guelfguat M, Leonidas JC, Springer S, Singh SP. Acute appendicitis in children: comparison of clinical diagnosis with ultrasound and CT imaging. Pediatr Radiol 2000; 30:94-98.[CrossRef][Medline]



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