Right Lower Quadrant Pain: Value of the Nonvisualized Appendix in Patients at Multidetector CT

Single institutional experience with initial ultrasound followed by computed tomography or magnetic resonance imaging for acute appendicitis in adults

PURPOSE

The objectives of this study was to assess the performance of ultrasound (US) for suspected appendicitis in adult patients and to evaluated the additive value of short-interval (within 1 week) computed tomography (CT) or Magnetic Resonance Imaging (MRI) after performing an initial US.

METHODS

In this IRB-approved, HIPAA-compliant, retrospective study, electronic medical records (EMRs) were queried for "US appendicitis" performed over a 2-year interval. EMR was reviewed for CT or MRI performed within 1 week of this exam, and if any new or additional information was available at subsequent exam. White count, patient disposition, and pathology, if surgery was performed, were also recorded.

RESULTS

682 patients underwent US for appendicitis over a 2-year duration, age range from 18 to 92 years (average: 30.1 years, M:F = 141:541). Findings showed 126/682 patients with normal appendix, 75/682 uncomplicated appendicitis, and 4/682 with complicated appendicitis. When performed, no additional findings were seen in these groups on short-interval CT or MRI. 2/682 patients had equivocal findings on US but eventually had normal appendix identified on CT. Four hundred and seventy-three patients had non-visualized appendix, of which only 14/473 (3.1%) eventually had appendicitis.

CONCLUSIONS

Ultrasound is an effective initial modality for evaluating appendicitis even in adult patients. Once a normal appendix, uncomplicated or complicated appendicitis is identified on US, no further imaging is necessary. Very few patients with non-visualization of the appendix eventually have appendicitis. Hence, these patients can be managed with active clinical follow-up rather than immediate CT or MRI. Symptoms and clinical scoring systems can be used for triage of these patients.

Visibility of Normal Appendix on CT, MRI, and Sonography: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of the present study is to assess the visibility of the normal appendix on CT, MRI, or ultrasound (US) images of a healthy population.

MATERIALS AND METHODS

The MEDLINE and EMBASE databases were searched to identify articles on the rates of detection of a normal appendix on CT, MRI, or US that appeared in the literature published up to January 20, 2017. Pooled detection rates were assessed using random-effects modeling, and rates associated with different imaging modalities were compared. Meta-regression analyses were performed to assess factors influencing detection rates and heterogeneity.

RESULTS

Thirty-two studies (21 CT studies with 5296 patients, 7 MRI studies with 600 patients, and 4 US studies with 1221 patients) were included in our meta-analysis. The overall normal appendix detection rate tended to be highest for CT (84%), followed by US (71%) and MR (69%), but no statistically significant differences were noted (for CT vs MRI, p = 0.16; for CT vs US, p = 0.23; and for MRI vs US, p = 0.91). Meta-regression analyses of the appendix detection rate with CT revealed that the year of publication of the study, the number of CT channels, and slice thickness affected study heterogeneity.

CONCLUSION

Normal appendixes seemed to be more visible on CT than on MRI or US, although this finding did not have statistical significance. With respect to CT, detection of normal appendixes was significantly better when more channels and thinner slices were used.

How to differentiate acute pelvic inflammatory disease from acute appendicitis ? A decision tree based on CT findings

PURPOSE

To construct a decision tree based on CT findings to differentiate acute pelvic inflammatory disease (PID) from acute appendicitis (AA) in women with lower abdominal pain and inflammatory syndrome.

MATERIALS AND METHODS

This retrospective study was approved by our institutional review board and informed consent was waived. Contrast-enhanced CT studies of 109 women with acute PID and 218 age-matched women with AA were retrospectively and independently reviewed by two radiologists to identify CT findings predictive of PID or AA. Surgical and laboratory data were used for the PID and AA reference standard. Appropriate tests were performed to compare PID and AA and a CT decision tree using the classification and regression tree (CART) algorithm was generated.

RESULTS

The median patient age was 28 years (interquartile range, 22-39 years). According to the decision tree, an appendiceal diameter ≥ 7 mm was the most discriminating criterion for differentiating acute PID and AA, followed by a left tubal diameter ≥ 10 mm, with a global accuracy of 98.2 % (95 % CI: 96-99.4).

CONCLUSION

Appendiceal diameter and left tubal thickening are the most discriminating CT criteria for differentiating acute PID from AA.

KEY POINTS

• Appendiceal diameter and marked left tubal thickening allow differentiating PID from AA. • PID should be considered if appendiceal diameter is < 7 mm. • Marked left tubal diameter indicates PID rather than AA when enlarged appendix. • No pathological CT findings were identified in 5 % of PID patients.

MRI of suspected appendicitis during pregnancy: interradiologist agreement, indeterminate interpretation and the meaning of non-visualization of the appendix

OBJECTIVE

To determine the degree of interradiologist agreement between the MRI features of appendicitis during pregnancy, the outcomes associated with an indeterminate interpretation and the negative predictive value of non-visualization of the appendix.

METHODS

Our study was approved by the institutional review board at the Washington University in St. Louis, Missouri (WUStL) and was HIPAA (Health Insurance Portability and Accountability Act of 1996)-compliant. The informed consent requirement was waived. Cases of suspected appendicitis during pregnancy evaluated using MRI were retrospectively identified using search queries. Scans were re-reviewed by two radiologists (7 and 9 years experience, respectively) to evaluate the interradiologist agreement of different MRI features of appendicitis during pregnancy (visualization of the appendix, appendiceal diameter, appendiceal wall thickening, periappendiceal fat stranding, fluid-filled appendix and periappendiceal fluid). The radiologists were blinded to patient outcome, patient intervention, laboratory data, demographic data and the original MRI reports. Clinical outcomes were documented by surgical pathology or clinical observation. Interradiologist agreement was analysed using Cohen's κ, while patient demographic and clinical data was analysed using Student's t-testing.

RESULTS

233 females with suspected appendicitis during pregnancy were evaluated using MRI over a 13-year period (mean age, 28.4 years; range, 17-38 years). There were 14 (6%) positive examinations for appendicitis during pregnancy, including 1 patient whose MRI was interpreted as negative, proven by surgical pathology. The presence of periappendiceal soft-tissue stranding and the final overall impression had the most interradiologist agreement (к = 0.81-1). There were no pregnant patients found to have acute appendicitis who had an indeterminate MR interpretation or when the appendix could not be visualized.

CONCLUSION

The final impression by the two retrospectively reviewing radiologists of MR examinations performed for suspected appendicitis during pregnancy had near-perfect agreement. In patients where the appendix could not be visualized or in patients that were interpreted as indeterminate, no patients had acute appendicitis. Advances in knowledge: MR impression for suspected appendicitis in the pregnant patient has high interradiologist agreement, and a non-visualized appendix or lack of inflammatory findings at the time of MR, reliably excludes surgical appendicitis.

The Reliability of a Standardized Reporting System for the Diagnosis of Appendicitis

PURPOSE

Computed tomography (CT) is a fast and ubiquitous tool to evaluate intra-abdominal organs and diagnose appendicitis. However, traditional CT reporting does not necessarily capture the degree of uncertainty and indeterminate findings are still common. The purpose of this study was to evaluate the reproducibility of a standardized CT reporting system for appendicitis across a large population and the system's impact on radiologists' certainty in diagnosing appendicitis.

METHODS

Using a previously described standardized reporting system, eight radiologists retrospectively evaluated CT scans, blinded to all clinical information, in a stratified random sample of 237 patients from a larger cohort of patients imaged for possible appendicitis (2010-2014). Receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were used to evaluate the diagnostic performance of readers for identifying appendicitis. Two-thirds of these scans were randomly selected to be independently read by a second reader, using the original CT reports to balance the number of positive, negative and indeterminate exams across all readers. Inter-reader agreement was evaluated.

RESULTS

There were 113 patients with appendicitis (mean age 38, 67% male). Using the standardized report, radiologists were highly accurate at identifying appendicitis (AUC=0.968, 95%CI confidence interval: 0.95, 0.99. Inter-reader agreement was >80% for most objective findings, and certainty in diagnosing appendicitis was high and reproducible (AUC=0.955 and AUC=0.936 for the first and second readers, respectively).

CONCLUSIONS

Using a standardized reporting system resulted in high reproducibility of objective CT findings for appendicitis and achieved high diagnostic accuracy in an at-risk population. Predictive tools based on this reporting system may further improve communication about certainty in diagnosis and guide patient management, especially when CT findings are indeterminate.

MRI for appendicitis in pregnancy: is seeing believing? clinical outcomes in cases of appendix nonvisualization

PURPOSE

The primary objective of this study was to determine the clinical outcomes in cases of appendix nonvisualization with MRI in pregnant patients with suspected appendicitis and the implications of appendix nonvisualization for excluding appendicitis.

METHODS

Fifty-eight pregnant patients with suspected appendicitis evaluated with MRI at three centers from a single institution were retrospectively reviewed by three radiologists with varying levels of abdominal imaging experience. All scans were performed on a 1.5-Tesla Siemens unit. Cases were evaluated for diagnostic quality, visualization of the appendix, presence of appendicitis, and alternate diagnoses. Clinical outcomes were gathered from the electronic medical record.

RESULTS

Of the 58 patients who underwent MRI for suspected appendicitis, 50 cases were considered adequate diagnostic quality by all three radiologists. The rate of appendix visualization among the three radiologists ranged from 60 to 76% (p = 0.44). The appendix was nonvisualized by at least one of the three radiologists in 25 cases (50%). Of these, none had a final diagnosis of appendicitis including one patient who underwent appendectomy. MRI suggested an alternate diagnosis in 6 (24%) patients with appendix nonvisualization. For the three reviewers, the agreement level on whether or not the appendix was visualized on the MRI had a Light's kappa value of 0.526, indicating a "moderate" level of agreement (p value < 0.01).

CONCLUSION

Despite only moderate level of interobserver agreement for appendix visualization, appendix nonvisualization on MRI in pregnant patients with suspected appendicitis confers a significant reduction in the risk of appendicitis compared to all comers as long as the study is adequate diagnostic quality and there are no secondary signs of appendicitis present.

Magnetic resonance imaging in pediatric appendicitis: a systematic review

Magnetic resonance imaging for the evaluation of appendicitis in children has rapidly increased recently. This change has been primarily driven by the desire to avoid CT radiation dose. This meta-analysis reviews the diagnostic performance of MRI for pediatric appendicitis and discusses current knowledge of cost-effectiveness. We used a conservative Haldane correction statistical method and found pooled diagnostic parameters including a sensitivity of 96.5% (95% confidence interval [CI]: 94.3-97.8%), specificity of 96.1% (95% CI: 93.5-97.7%), positive predictive value of 92.0% (95% CI: 89.3-94.0%) and negative predictive value of 98.3% (95% CI: 97.3-99.0%), based on 11 studies. Assessment of patient outcomes associated with MRI use at two institutions indicates that time to antibiotics was 4.7 h and 8.2 h, time to appendectomy was 9.1 h and 13.9 h, and negative appendectomy rate was 3.1% and 1.4%, respectively. Alternative diagnoses were present in ~20% of cases, most commonly adnexal cysts and enteritis/colitis. Regarding technique, half-acquisition single-shot fast spin-echo (SSFSE) pulse sequences are crucial. While gadolinium-enhanced T1-weighted pulse sequences might be helpful, any benefit beyond non-contrast MRI has not been confirmed. Balanced steady-state free precession (SSFP) sequences are generally noncontributory. Protocols do not need to exceed five sequences; four-sequence protocols are commonly utilized. Sedation generally is not indicated; patients younger than 5 years might be attempted based on the child's ability to cooperate. A comprehensive pediatric cost-effectiveness analysis that includes both direct and indirect costs is needed.

Use of advanced imaging techniques during visits to emergency departments--implications, costs, patient benefits/risks

25 years ago, on a Friday evening at 9 pm, the emergency department (ED) was full of patients with a wide range of clinical problems. Their investigations included plain radiographs, but no other imaging was included until the next working day. At present, many patients are receiving advanced imaging such as ultrasound, CT and MRI, often delivered out of hours--an obvious advance for patients or sometimes an unnecessary development? In this article, we will consider how to assess patient benefits and whether increased use of advanced imaging is an overall advance for patients. We will address the general implications for healthcare services which come with greater use of advanced imaging. We will then address the effect of advanced imaging on individual fictional ED patients with a variety of complaints.

Intra-Appendiceal Air at CT: Is It a Useful or a Confusing Sign for the Diagnosis of Acute Appendicitis?

Objective

To investigate the significance of intra-appendiceal air at CT for the evaluation of appendicitis.

Materials and Methods

We retrospectively analyzed 458 patients (216 men, 242 women; age range, 18-91 years) who underwent CT for suspected appendicitis. Two independent readers reviewed the CT. Prevalence, amount, and appearance of intra-appendiceal air were assessed and compared between the patients with and without appendicitis. Performance of CT diagnosis was evaluated in two reading strategies: once ignoring appendiceal air (strategy 1), and the other time considering presence of appendiceal air as indicative of no appendicitis in otherwise indeterminate cases (strategy 2), using receiver operating characteristic (ROC) analysis.

Results

Of the 458 patients, 102 had confirmed appendicitis. The prevalence of intra-appendiceal air was significantly different between patients with (13.2%) and without (79.8%) appendicitis (p < 0.001). The amount of appendiceal air was significantly lesser in patients having appendicitis as compared with the normal group, for both reader 1 (p = 0.011) and reader 2 (p = 0.002). Stool-like appearance and air-fluid levels were more common in the appendicitis group than in the normal appendix for both readers (p < 0.05). Areas under the ROC curves were not significantly different between strategies 1 and 2 in reader 1 (0.971 vs. 0.985, respectively; p = 0.056), but showed a small difference in reader 2 (0.969 vs. 0.986, respectively; p = 0.042).

Conclusion

Although significant differences were seen in the prevalence, amount, and appearance of intra-appendiceal air between patients with and without appendicitis, it has a limited incremental value for the diagnosis of acute appendicitis.

Initial Performance of Radiologists and Radiology Residents in Interpreting Low-Dose (2-mSv) Appendiceal CT

OBJECTIVE

The objective of our study was to prospectively evaluate the initial diagnostic performance and learning curve of a community of radiologists and residents in interpreting 2-mSv appendiceal CT.

SUBJECTS AND METHODS

We included 46 attending radiologists and 153 radiology residents from 22 hospitals who completed an online training course of 30 2-mSv CT cases. Appendicitis was confirmed in 14 cases. Most of the readers had limited (≤ 10 cases, n = 32) or no (n = 118) prior experience with low-dose appendiceal CT. The order of cases was randomized for each reader. A multireader multicase ROC analysis was performed. Generalized estimating equations were used to model the learning curves in diagnostic performance.

RESULTS

Diagnostic performance gradually improved with years of training. The average AUC was 0.94 (95% CI, 0.90-0.98), 0.92 (0.88-0.96), 0.90 (0.85-0.96), and 0.86 (0.80-0.92) for the attending radiologists, senior residents, 2nd-year residents, and 1st-year residents, respectively. We did not observe any notable intrareader learning curves over the training course of the 30 cases except a decrease in reading time. Diagnostic accuracy and sensitivity were significantly affected by the reader training level and prior overall experience with appendiceal CT but not by the prior specific experience with low-dose appendiceal CT.

CONCLUSION

The learning curve is likely prolonged and forms gradually over years by overall radiology training and clinical experience in general rather than by experience with low-dose appendiceal CT specifically.

Utility of magnetic resonance imaging for suspected appendicitis in pregnant women

OBJECTIVE

The purpose of this study was to estimate the rate and risk of appendix nonvisualization and alternative diagnoses made with magnetic resonance imaging (MRI) for suspected appendicitis in pregnant women.

STUDY DESIGN

We performed a retrospective cohort study of consecutive pregnant women who underwent MRI for suspected appendicitis at a single center from 2007-2012. Data on clinical presentation, imaging, and surgical pathologic evidence were extracted from electronic medical records. Odds ratios estimated risk factors for nondiagnosis. Radiologic diagnoses were identified, and rates of diagnoses were calculated. Subgroup analysis was performed among women who underwent initial imaging with ultrasound scanning.

RESULTS

Over the 5-year period, 171 pregnant women underwent MRI for suspected appendicitis. The rate of nonvisualization was 30.9% (n = 53). Of the remaining 118 women with a visualized appendix, 18 women had imaging findings that were consistent with appendicitis and underwent appendectomy. Twelve cases of appendicitis were confirmed on pathologic evaluation (66.7%). Women with nonvisualization of the appendix on MRI were more likely to be beyond the first trimester (odds ratio, 2.1; 95% confidence interval, 1.0-4.5). Seventy-four women had disease diagnosed on MRI (43.3%). In the group of 43 women who had a nondiagnostic ultrasound scanning before the MRI, the rate of subsequent diagnostic MRI was 65% (n = 28).

CONCLUSION

MRI yields a high diagnostic rate and accuracy in pregnant women with suspected appendicitis and provides alternative diagnoses to guide further management. Given the high rate of appendix nonvisualization on ultrasound scanning that has been reported in the literature, we recommend MRI as the imaging modality of choice for this population in settings in which MRI is readily available.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

Current radiological strategies for the assessment of right lower quadrant abdominal pain

Right lower quadrant abdominal pain is a common clinical entity. Imaging and the radiologistplay an integral role in achieving a diagnosis, so guiding prompt management of patients.This review discusses the spectrum of pathology and imaging findings, and highlights and contrasts the preferred imaging modalities in different subsets of patients.

The accuracy of pre-appendectomy computed tomography with histopathological correlation: a clinical audit, case discussion and evaluation of the literature

The increasing use of computed tomography (CT) in acute appendicitis makes recognising the radiological hallmarks of the condition and its mimics vital. The differential diagnosis includes both appendiceal and nonappendiceal pathologies. The correlation between pre-appendectomy CT and post-appendectomy histopathology was audited retrospectively. Cases of clinico-histopathological discrepancy underwent blind peer-review, and possible improvements were discussed in the context of the medical literature. A grade for discrepancy was given based on the RADPEER scoring system, and interesting or discrepant cases were examined more closely to identify targets for education. Of the 199 procedures, 4 appendectomies were negative (histologically normal), 182 were positive (primary appendicitis) and 13 were incidental (another primary process caused inflammation). The positive predictive value for pre-appendectomy CT was 91.5 %, and the negative appendectomy rate was 2 %. There were many secondary pathologies, including neoplasia, tuberculosis and endometriosis. Although no CT reports missed a diagnosis that should be made “almost all of the time” and in 96 % of cases, the second, blinded radiologist agreed with the initial assessment, in 3 cases, a missed diagnosis altered clinical management; 2 were “understandable” misses but 1 was not. In five cases, a discrepancy was “understandable” but clinically insignificant. Overall, in comparison to the medical literature, the degree of clinico-histopathological correlation was good. Although identifying areas for improvement was challenging, after a pictorial review of four cases and a discussion of the medical literature, we present our audit results and some valuable learning points for use in the CT assessment of suspected acute appendicitis.

An update on common gastrointestinal emergencies

The evaluation of the child with acute abdominal pain often poses as a diagnostic challenge due to the wide range of diagnoses. Surgical emergencies need to be rapidly identified and managed appropriately to minimize morbidity and mortality. Presenting symptoms, clinical examination, and laboratory findings can guide selection of diagnostic imaging. This article reviews common surgical causes of abdominal pain in children.

Computed tomography with intravenous contrast alone: the role of intra-abdominal fat on the ability to visualize the normal appendix in children

BACKGROUND

Computed tomography (CT) with enteric contrast is frequently used to evaluate children with suspected appendicitis. The use of CT with intravenous (IV) contrast alone (CT IV) may be sufficient, however, particularly in patients with adequate intra-abdominal fat (IAF).

OBJECTIVES

The authors aimed 1) to determine the ability of radiologists to visualize the normal (nondiseased) appendix with CT IV in children and to assess whether IAF adequacy affects this ability and 2) to assess the association between IAF adequacy and patient characteristics.

METHODS

This was a retrospective 16-center study using a preexisting database of abdominal CT scans. Children 3 to 18 years who had CT IV scan and measured weights and for whom appendectomy history was known from medical record review were included. The sample was chosen based on age to yield a sample with and without adequate IAF. Radiologists at each center reread their site's CT IV scans to assess appendix visualization and IAF adequacy. IAF was categorized as "adequate" if there was any amount of fat completely surrounding the cecum and "inadequate" if otherwise.

RESULTS

A total of 280 patients were included, with mean age of 10.6 years (range = 3.1 to 17.9 years). All 280 had no history of prior appendectomy; therefore, each patient had a presumed normal appendix. A total of 102 patients (36.4%) had adequate IAF. The proportion of normal appendices visualized with CT IV was 72.9% (95% confidence interval [CI] = 67.2% to 78.0%); the proportions were 89% (95% CI = 81.5% to 94.5%) and 63% (95% CI = 56.0% to 70.6%) in those with and without adequate IAF (95% CI for difference of proportions = 16% to 36%). Greater weight and older age were strongly associated with IAF adequacy (p < 0.001), with weight appearing to be a stronger predictor, particularly in females. Although statistically associated, there was noted overlap in the weights and ages of those with and without adequate IAF.

CONCLUSIONS

Protocols using CT with IV contrast alone to visualize the appendix can reasonably include weight, age, or both as considerations for determining when this approach is appropriate. However, although IAF will more frequently be adequate in older, heavier patients, highly accurate prediction of IAF adequacy appears challenging solely based on age and weight.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis

OBJECTIVE

To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT.

METHODS

This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used.

RESULTS

46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M.

CONCLUSION

Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis.

ADVANCES IN KNOWLEDGE

In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.

Integrating MR imaging into the clinical workup of pregnant patients suspected of having appendicitis is associated with a lower negative laparotomy rate: single-institution study

PURPOSE

To determine if integrating magnetic resonance (MR) imaging into the workup of right lower quadrant pain in pregnant patients was associated with improved outcomes as measured by the negative laparotomy rate (NLR) and the perforation rate (PR).

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective review of medical records. Two hundred sixty-seven pregnant patients who underwent either surgery (n = 82) or an MR imaging examination (n = 217) because of suspicion of appendicitis between January 1, 1996, and August 31, 2011, were identified. Relevant ultrasonographic and MR imaging reports were classified as showing true-positive, false-positive, true-negative, false-negative, or equivocal findings. MR imaging utilization was analyzed to define pre- and post-MR imaging cohorts. NLR and PR were calculated for both cohorts and were compared by using a Fisher exact probability test. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for MR imaging were calculated.

RESULTS

MR imaging was introduced into the clinical workup in 2004. From 1996 to 2003, the NLR for pregnant patients was 55% (17 of 31), and the PR was 21% (three of 14). From 2004 to 2011, the NLR was 29% (15 of 51), and the PR was 26% (nine of 35). The 47% decline in the NLR ([55%-29%]/55%) was statistically significant (P = .02). The change in PR was not significant (P > .99). The sensitivity, specificity, PPV, and NPV of MR imaging in the diagnosis of appendicitis were 89% (17 of 19), 97% (187 of 193), 74% (17 of 23), and 99% (187 of 189), respectively.

CONCLUSION

The routine incorporation of MR imaging into the clinical workup for suspicion of appendicitis in pregnant patients at this institution was associated with a decrease in the NLR of 47% without a significant change in the PR.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12121027/-/DC1.

Handheld device review of abdominal CT for the evaluation of acute appendicitis

Advances in handheld computing now allow review of DICOM datasets from remote locations. As the diagnostic ability of this tool is unproven, we evaluated the ability to diagnose acute appendicitis on abdominal CT using a mobile DICOM viewer. This HIPAA compliant study was IRB-approved. Twenty-five abdominal CT studies from patients with RLQ pain were interpreted on a handheld device (iPhone) using a DICOM viewer (OsiriX mobile) by five radiologists. All patients had surgical confirmation of acute appendicitis or follow-up confirming no acute appendicitis. Studies were evaluated for the ability to find the appendix, maximum appendiceal diameter, presence of an appendicolith, periappendiceal stranding and fluid, abscess, and an assessment of the diagnosis of acute appendicitis. Results were compared to PACS workstation. Fifteen cases of acute appendicitis were correctly identified on 98% of interpretations, with no false-positives. Eight appendicoliths were correctly identified on 88% of interpretations. Three abscesses were correctly identified by all readers. Handheld device measurement of appendiceal diameter had a mean 8.6% larger than PACS measurements (p = 0.035). Evaluation for acute appendicitis on abdominal CT studies using a portable device DICOM viewer can be performed with good concordance to reads performed on PACS workstations.

MRI for clinically suspected pediatric appendicitis: an implemented program

BACKGROUND

Emergent MRI is now a viable alternative to CT for evaluating appendicitis while avoiding the detrimental effects of ionizing radiation. However, primary employment of MRI in the setting of clinically suspected pediatric appendicitis has remained significantly underutilized.

OBJECTIVE

To describe our institution's development and the results of a fully implemented clinical program using MRI as the primary imaging evaluation for children with suspected appendicitis.

MATERIALS AND METHODS

A four-sequence MRI protocol consisting of coronal and axial single-shot turbo spin-echo (SS-TSE) T2, coronal spectral adiabatic inversion recovery (SPAIR), and axial SS-TSE T2 with fat saturation was performed on 208 children, ages 3 to 17 years, with clinically suspected appendicitis. No intravenous or oral contrast material was administered. No sedation was administered. Data collection includes two separate areas: time parameter analysis and MRI diagnostic results.

RESULTS

Diagnostic accuracy of MRI for pediatric appendicitis indicated a sensitivity of 97.6% (CI: 87.1-99.9%), specificity 97.0% (CI: 93.2-99.0%), positive predictive value 88.9% (CI: 76.0-96.3%), and negative predictive value 99.4% (CI: 96.6-99.9%). Time parameter analysis indicated clinical feasibility, with time requested to first sequence obtained mean of 78.7 +/- 52.5 min, median 65 min; first-to-last sequence time stamp mean 14.2 +/- 8.8 min, median 12 min; last sequence to report mean 57.4 +/- 35.2 min, median 46 min. Mean age was 11.2 +/- 3.6 years old. Girls represented 57% of patients.

CONCLUSION

MRI is an effective and efficient method of imaging children with clinically suspected appendicitis. Using an expedited four-sequence protocol, sensitivity and specificity are comparable to CT while avoiding the detrimental effects of ionizing radiation.

Beyond appendicitis: common and uncommon gastrointestinal causes of right lower quadrant abdominal pain at multidetector CT

Right lower quadrant abdominal pain is one of the most common causes of a patient visit to the emergency department. Although appendicitis is the most common condition requiring surgery in patients with abdominal pain, right lower quadrant pain can be indicative of a vast list of differential diagnoses and is thus a challenge for clinicians. Other causes of right lower quadrant pain beyond appendicitis include inflammatory and infectious conditions involving the ileocecal region; diverticulitis; malignancies; conditions affecting the epiploic appendages, omentum, and mesentery; and miscellaneous conditions. Multidetector computed tomography (CT) has emerged as the modality of choice for evaluation of patients with several acute traumatic and nontraumatic conditions causing right lower quadrant pain. Multidetector CT is an extremely useful noninvasive method for diagnosis and management of not only the most common causes such as appendicitis but also less common conditions.

Differentiation between right tubo-ovarian abscess and appendicitis using CT--a diagnostic challenge

AIM

To determine CT features that can potentially differentiate right tubo-ovarian abscess (TOA) from acute appendicitis (AA; including abscess formation).

MATERIALS AND METHODS

The abdominal computed tomography (CT) images of 48 patients with right-sided TOA (average age 39.3 ± 9.8 years) and 80 patients (average age 53.5 ± 19.9 years) with AA (24 with peri-appendicular abscess) were retrospectively evaluated. Two experienced radiologists evaluated 12 CT signs (including enlarged, thickened wall ovary, appendix diameter and wall thickness, peri-appendicular fluid collection, adjacent bowel wall thickening, fat stranding, free fluid, and extraluminal gas) in consensus to categorize the studies as either TOA or AA. The diagnosis and the frequency of each of the signs were correlated with the surgical and clinical outcome.

RESULTS

Reviewers classified 92% cases correctly (TOA=85%, AA=96.3%), 3% incorrectly (TOA=6.3%, AA=1.3%); 5% were equivocal (TOA=8.3%, AA=2.5%). In the peri-appendicular abscess group reviewers were correct in 100%. Frequent findings in the TOA group were an abnormal ovary (87.5%), peri-ovarian fat stranding (58.3%), and recto-sigmoid wall thickening (37.5%). An abnormal appendix was observed in 2% of TOA patients. Frequent findings in the AA group were a thickened wall (32.5%) and distended (80%) appendix. Recto-sigmoid wall thickening was less frequent in AA (12.5%). The appendix was not identified in 45.8% of the TOA patients compared to 15% AA.

CONCLUSIONS

In the presence of a right lower quadrant inflammatory mass, peri-ovarian fat stranding, thickened recto-sigmoid wall, and a normal appearing caecum, in young patients favour the diagnosis of TOA. An unidentified appendix does not contribute to the differentiation between TOA and peri-appendicular abscess.

Influence of body habitus and use of oral contrast on reader confidence in patients with suspected acute appendicitis using 64 MDCT

The purpose of this study is to evaluate how body habitus affects reader confidence in diagnosing acute appendicitis and appendiceal visualization using 64 MDCT technology with and without oral contrast. We conducted a HIPAA compliant, IRB approved study of adult patients presenting to the Emergency Department with nontraumatic abdominal pain. Subjects were randomized to two groups: 64 MDCT scans performed with oral and intravenous contrast or scans performed solely with intravenous contrast. Three radiologists established their confidence about the presence of appendicitis as well as recording whether the appendix was visualized. Reader confidence in diagnosing acute appendicitis was compared between the two groups for the three readers. The impact of patient BMI and estimated intra-abdominal fat on reader confidence in diagnosing appendicitis was determined. Finally, a comparison of the effect of BMI and intra-abdominal fat on appendiceal visualization between the two groups was carried out. Three hundred three patients were enrolled in this study. There was a statistically significant difference in confidence based on BMI for reader 2, group 1 in diagnosing appendicitis. No further statistically significant differences in reader confidence for diagnosing appendicitis based on BMI or intra-abdominal fat were identified. There was no influence of BMI or intra-abdominal fat on appendiceal visualization. Increasing BMI was seen to improve reader confidence for one of three readers in patients that received both oral and intravenous contrast. No further effects of BMI or intra-abdominal fat on confidence in diagnosing or excluding appendicitis were seen. Neither BMI nor intra-abdominal fat were seen to influence appendiceal visualization.

[Rational diagnostics of acute abdomen]

BACKGROUND

In view of the threat that comes with an acute abdomen, it is of major importance that diagnostics are executed quickly and efficiently. In the course of this two tendencies can be differentiated: 1) general use of complex examination (e.g. CT, MRT) of all potential patients and 2) step-by-step-diagnostics with advanced diagnostics as and when required.

MATERIAL AND METHODS

A total of 444 patients with an acute abdomen as admission diagnosis were investigated. All data were evaluated prospectively and analyzed retrospectively. All patients had the same basic diagnostics consisting of aclinical history, clinical examination, laboratory examination, abdominal sonography and x-ray overview images. These examinations were supplemented when required by advanced measures, such as CT, colon enema with contrast fluid, endoscopic examination and diagnostic laparotomy.

RESULTS

Three different disease groups of unequal diagnostic need could be identified. The first group, presented in the form of an appendicitis showed that in 80% of all patients a basic diagnosis was sufficient. Advanced examination such as CT affected 14%. The negative appendectomy rate amounted to 8%. Other diseases belonging to the first group were ileus, acute biliary diseases, perforation etc. In the second group presented in the form of a diverticulitis, an advanced radiological examination was required in 84% of all cases. Similar results are also expected in cases of pancreatitis. In the third group presented in the form of coprostasis, inflammatory etiology was found in 39% of all secondary diseases. However the symptoms became clinically apparent after treatment of the coprostasis. In this group a basic diagnosis was satisfactory in 84% of cases, however, a diagnostic laparotomy was inevitable for 3% of these patients.

CONCLUSION

Generally step-by-step diagnostic approach has proven itself to be efficient. For 80% of all patients it makes advanced diagnostic measures unnecessary. The exceptions are diseases in which it is necessary to know not only the diagnosis but also the disease stage. In these cases (e.g. pancreatitis, diverticulitis etc.) advanced diagnostics should be pursued from the onset. The necessity of a diagnostic laparotomy has lost importance for 1% of all patients.

CT enterography

Conventional radiologic and endoscopic evaluations of the small bowel are often limited by the length, caliber, and motility of the small bowel loops. The development of new multidetector-row CT scanners, with faster scan times and isotropic spatial resolution, allows high-resolution multiphasic and multiplanar assessment of the bowel, bowel wall, and lumen. CT Enterography (CTE) is a variant of routine abdominal scanning, geared toward more sustained bowel filling with oral contrast material, and the use of multiplanar images, that can enhance gastrointestinal (GI) tract imaging. This article examines the techniques and clinical applications of CTE in comparison with CT enteroclysis, focusing on Crohn disease, obscure GI bleeding, GI tumors, acute abdominal pain, and bowel obstruction.

Making the diagnosis of acute appendicitis: do more preoperative CT scans mean fewer negative appendectomies? A 10-year study

PURPOSE

To determine the frequency of preoperative computed tomography (CT) in the evaluation of patients suspected of having appendicitis at one institution during the past 10 years and to determine whether changes in CT utilization were associated with changes in the negative appendectomy rate.

MATERIALS AND METHODS

Institutional review board approval was obtained, and a waiver of informed consent was granted for this HIPAA-compliant study. A surgical database search yielded medical record numbers of 925 patients (526 [ 56.9%] men and 399 [43.1%] women; mean age, 38 years (range, 18-95 years]) who underwent urgent appendectomy between January 1998 and September 2007. Patients who were younger than 18 years of age at the time of surgery were excluded. CT, pathology, and surgery reports were reviewed. By using logistic regression, changes in the proportion of patients undergoing CT and in the proportion of patients undergoing each year appendectomy in which the appendix was healthy were evaluated. Subgroup analyses based on patient age (<or= 45 years or > 45 years) and sex also were performed.

RESULTS

Prior to urgent appendectomy, 18.5% of patients underwent preoperative CT in 1998 compared with 93.2% of patients in 2007. The negative appendectomy rate for women 45 years of age and younger decreased from 42.9% in 1998% to 7.1% in 2007. However, the timing of the decline in negative appendectomy rates for women 45 years and younger could not be proved to be associated with the increase in CT use. There was no significant trend toward a lower negative appendectomy rate for men regardless of age or for women older than 45 years of age with increased use of preoperative CT. The shift from single-detector CT to multidetector CT and the use of decreasing section thickness also correlated with a reduction in false-positive diagnoses.

CONCLUSION

Rising utilization of preoperative CT and advances in technology coincided with a decrease in the negative appendectomy rate for women 45 years and younger but not in men of any age or women older than 45 years.

Hotel NHS and the acute abdomen - admit first, investigate later

AIM

To determine the financial consequences of a policy of admission first, followed by definitive investigation for patients with an admission diagnosis of suspected acute abdomen.

RESULTS

Over a 1-month period, 122 patients were admitted with a suspected surgical diagnosis of acute abdomen (55 men, 67 women); age range 16-95 years (median: 56.5). Based on surgical operation required (n = 36), death after admission (n = 6, three postoperative deaths) and/or severe surgical illness (n = 17), 56 required surgical inpatient admission, while 66 did not. The patients who did not require admission spent significantly shorter time in hospital than those who required admission (median: 5 days vs. 8.5 days; p = 0.0000). Total hospital hotel and investigation cost (not including ITU or theatre costs) for all 122 patients was 330,468 pounds. Overall, 205,468 pounds was consumed by these 56 patients who required admission, while 125,000 pounds was spent on 66 patients whose clinical course did not justify admission; 92% of which was spent on hospital hotel costs and 8% on the cost of imaging and/or endoscopy.

DISCUSSION AND CONCLUSION

On a national basis, emergency General Surgery admissions account for 1000 Finished Consultant Episodes per 100,000 population. The findings of this study suggest that this equates to a national NHS spend of 650 million pounds each year, for the hotel costs of patients that could arguably avoid surgical admission altogether. Continuing to admit patients with a suspected acute abdomen first and then requesting definitive investigation makes neither clinical nor economic sense.

Diagnosis of acute appendicitis with sliding slab ray-sum interpretation of low-dose unenhanced CT and standard-dose i.v. contrast-enhanced CT scans

OBJECTIVE

The purpose of this study was to compare low-dose unenhanced CT with standard-dose i.v. contrast-enhanced CT in the diagnosis of appendicitis.

MATERIALS AND METHODS

Two hundred seven adults with suspected appendicitis underwent CT with mean effective doses of both 4.2 and 8.0 mSv. Two radiologists retrospectively reviewed thin-section images by sliding a 5-mm-thick ray-sum slab. They rated the likelihood of appendicitis and appendiceal visualization on 5- and 3-point scales, respectively, and proposed alternative diagnoses. Likelihood > or = 3 was considered a positive diagnosis. Receiver operating characteristics analysis, the McNemar test, and the Wilcoxon's signed-rank test were used.

RESULTS

Seventy-eight patients had appendicitis. The values of the area under the receiver operating characteristics curve were 0.98 for the low-dose unenhanced acquisition and 0.97 for the standard-dose contrast-enhanced acquisition for reader 1 (95% CI for the difference, -0.02 to 0.03) and 0.99 and 0.98 (-0.02 to 0.02) for reader 2. Sensitivity was 98.7% for low-dose unenhanced CT and 100% for standard-dose contrast-enhanced CT for reader 1 (p = 1.00) and 100% for both techniques for reader 2. Specificity was 95.3% and 93.0% (p = 0.25) and 96.9% and 96.9%. The interpretation was indeterminate (score 3) in 0.5% and 1.4% of cases for reader 1 (p = 0.63) and 0.5% and 0% for reader 2 (p = 1.00). A normal appendix was not visualized in 5.4% and 3.9% of cases by reader 1 (p = 0.63) and 3.9% and 2.3% of cases by reader 2 (p = 0.50). None of the patients whose appendix was not visualized had appendicitis. Diagnostic confidence, visualization score for a normal appendix, and correct alternative diagnosis tended to be compromised with use of low-dose unenhanced CT, showing a significant difference for a reader's confidence in the diagnosis of appendicitis (p = 0.004). The two techniques were comparable in the diagnosis of appendiceal perforation.

CONCLUSION

Low-dose unenhanced CT is potentially useful in the diagnosis of appendicitis.

Pregnant patients suspected of having acute appendicitis: effect of MR imaging on negative laparotomy rate and appendiceal perforation rate

PURPOSE

To investigate the effect of magnetic resonance (MR) imaging on the negative laparotomy rate (NLR) and the perforation rate (PR) in pregnant patients suspected of having acute appendicitis (AA) and to assess the need for computed tomography (CT) in this setting.

MATERIALS AND METHODS

The data of 148 consecutive pregnant patients (mean age, 29 years; age range, 15-42 years; mean gestational age, 20 weeks; gestational age range, 4-37 weeks) who were clinically suspected of having AA and examined with MR imaging between March 2002 and August 2007 were retrospectively analyzed in an institutional review board-approved HIPAA-compliant protocol. One hundred forty patients underwent ultrasonography (US) before MR imaging. The clinical and laboratory data and the findings of the initial US and MR image interpretations were recorded and analyzed at Student t and Fisher exact testing. The NLR and PR were calculated.

RESULTS

Fourteen (10%) patients had AA, and perforation occurred in three (21%) of them. US results were positive for AA in five (36%) patients with proved AA. MR results were positive in all 14 patients with AA. MR results were negative in 125 of the 134 patients without AA; there were nine false-positive cases (two positive, seven inconclusive). Among the patients without AA, the normal appendix could be visualized on US images in less than 2% (two of 126) of cases and on MR images in 87% (116 of 134) of cases (P < .0001). Twenty-seven (18%) patients underwent surgical exploration, and eight of them had negative laparotomy results, yielding an NLR of 30% and a PR of 21% (three of 14 patients). Only four (3%) patients underwent CT.

CONCLUSION

For pregnant patients clinically suspected of having AA, use of MR imaging yields favorable combinations of NLR and PR compared with previously reported values. The radiation exposure associated with CT examination can be avoided in most cases.

Magnetic resonance of acute appendicitis: pearls and pitfalls

Acute appendicitis is the most common surgical abdominal emergency. Although the clinical diagnosis can be made accurately in typical cases, imaging plays an important role in improving diagnostic accuracy of this condition, especially when the clinical diagnosis is uncertain. Magnetic resonance imaging is an emerging promising technique for the diagnosis of acute appendicitis, especially in patients with nondiagnostic ultrasound and in patients where radiation is a clinical concern. In the following review, the role of magnetic resonance in the diagnosis of appendicitis will be discussed.

Computed tomography evaluation of the normal appendix: comparison of low-dose and standard-dose unenhanced helical computed tomography

OBJECTIVE

To determine the visualization rate of the normal appendix on low- and standard-dose unenhanced computed tomography (CT) and to evaluate the variables that may influence the identification of the appendix.

METHODS

The study population was derived from the previous study, approved by the internal review board, investigating the effectiveness of low-dose CT (LDCT) in diagnosis of urolithiasis. Sixty-eight patients presenting with acute flank pain underwent 2 unenhanced dual-slice CT examinations. Standard-dose CT (SDCT) scans were obtained using 2 x 5-mm collimation, 120 kVp, and 170 effective mAs and followed by LDCT using 30 or 50 effective mAs. Two independent board-certified radiologists retrospectively recorded the visualization, outer diameter, and the wall thickness of normal appendices. The diameters, circumference, and cross-sectional area of the abdomen were measured.

RESULTS

The prevalence of appendectomy was 8.8% (6 of 68 patients). The means of the 2 reviewers' sensitivity, specificity, positive and negative predictive values, and accuracy for visualization of normal appendix at SDCT versus LDCT respectively were 78% versus 73%, 100% versus 92%, 100% versus 99%, 31% versus 24%, and 80% versus 74% (P = 0.39-0.75). The interobserver agreement was good at both SDCT (kappa = 0.61) and LDCT (kappa = 0.74). Overall 40% to 58% of appendices at LDCT and 33% to 47% at SDCT was larger than 6 mm. There was no significant correlation in the appendix visualization neither with abdominal dimensions nor with visceral or pericecal fat at both dose sets. The calculated mean effective radiation dose at LDCT was 70% to 82% less than SDCT.

CONCLUSIONS

Low- and standard-dose nonenhanced helical CT can visualize a normal appendix with high accuracy and good interobserver agreement. The diameter of normal appendix overlaps with that of appendicitis at CT. A diameter of 10.0 mm should be considered as the upper limit of normal in the absence of any other CT signs of appendicitis.

What clinical and laboratory parameters determine significant intra abdominal pathology for patients assessed in hospital with acute abdominal pain?

BACKGROUND

Abdominal pain is a common cause for emergency admission. While some patients have serious abdominal pathology, a significant group of those patients have no specific cause for the pain. This study was conducted to identify those who have non-specific abdominal pain who can be either admitted short term for observation or reassured and discharged for outpatient management.

PATIENTS AND METHODS

A prospective documentation of clinical and laboratory data was obtained on a consecutive cohort of 286 patients who were admitted to a surgical unit over a nine month period with symptoms of abdominal pain regarded severe enough for full assessment in the casualty department and admission to a surgical ward. The patients were followed until a definite diagnosis was made or the patient's condition and abdominal pain improved and the patient discharged. The hospital where the study took place is a small peripheral general hospital draining a population of 120,000 people in a rural area in New Zealand.

RESULTS

There were 286 admissions to the emergency department. Logistic regression multivariate statistical analysis showed that guarding raised white cells count, tachycardia and vomiting were the only variables associated with significant pathology.

CONCLUSION

Patients with no vomiting, no guarding, who have normal pulse rates and normal white cell counts are unlikely to have significant pathology requiring further active intervention either medical or surgical.

Difficulties in the diagnosis of appendicitis: review of CT and US images

To determine the reasons for missing a distended appendix, we discuss cases of acute appendicitis in which either or both computed tomography (CT) and/or ultrasonography (US) initially failed to detect distended appendix. In some cases, distended appendices that were undetected on US were easily detected by CT, and vice versa. Failure to detect a distended appendix does not always eliminate the possibility of acute appendicitis.