Secondary imaging for suspected appendicitis after equivocal ultrasound: time to disposition of MRI compared to CT

The Society for Pediatric Radiology Magnetic Resonance Imaging and Emergency and Trauma Imaging Committees' consensus protocol recommendation for rapid MRI for evaluating suspected appendicitis in children

The imaging evaluation of acute abdominal pain in children with suspected appendicitis has evolved to include rapid abdominopelvic MRI (rMRI) over recent years. Through a collaborative effort between the Magnetic Resonance Imaging (MRI) and Emergency and Trauma Imaging Committees of the Society for Pediatric Radiology (SPR), we conducted a survey on the utilization of rMRI to assess practice specifics and protocols. Subsequently, we present a proposed consensus rMRI protocol derived from the survey results, literature review, and discussion and consensus between committee members.

Diagnosis and treatment of appendicitis: systematic review and meta-analysis

BACKGROUND

The optimal diagnosis and treatment of appendicitis remains controversial. This systematic review details the evidence and current best practices for the evaluation and management of uncomplicated and complicated appendicitis in adults and children.

METHODS

Eight questions regarding the diagnosis and management of appendicitis were formulated. PubMed, Embase, CINAHL, Cochrane and clinicaltrials.gov/NLM were queried for articles published from 2010 to 2022 with key words related to at least one question. Randomized and non-randomized studies were included. Two reviewers screened each publication for eligibility and then extracted data from eligible studies. Random effects meta-analyses were performed on all quantitative data. The quality of randomized and non-randomized studies was assessed using the Cochrane Risk of Bias 2.0 or Newcastle Ottawa Scale, respectively.

RESULTS

2792 studies were screened and 261 were included. Most had a high risk of bias. Computerized tomography scan yielded the highest sensitivity (> 80%) and specificity (> 93%) in the adult population, although high variability existed. In adults with uncomplicated appendicitis, non-operative management resulted in higher odds of readmission (OR 6.10) and need for operation (OR 20.09), but less time to return to work/school (SMD - 1.78). In pediatric patients with uncomplicated appendicitis, non-operative management also resulted in higher odds of need for operation (OR 38.31). In adult patients with complicated appendicitis, there were higher odds of need for operation following antibiotic treatment only (OR 29.00), while pediatric patients had higher odds of abscess formation (OR 2.23). In pediatric patients undergoing appendectomy for complicated appendicitis, higher risk of reoperation at any time point was observed in patients who had drains placed at the time of operation (RR 2.04).

CONCLUSIONS

This review demonstrates the diagnosis and treatment of appendicitis remains nuanced. A personalized approach and appropriate patient selection remain key to treatment success. Further research on controversies in treatment would be useful for optimal management.

Rapid MRI Abdomen for Assessment of Clinically Suspected Acute Appendicitis in the General Adult Population: a Systematic Review

OBJECTIVES

To perform a systematic review on the use of magnetic resonance imaging (MRI) of the abdomen to evaluate clinically suspected appendicitis in the general adult population. We examined the diagnostic accuracy, the reported trends of MRI use, and the factors that affect the utility of MRI abdomen, including study duration and cost-benefits.

METHODS

We conducted a systematic literature search on PubMed, MEDLINE, Embase, Web of Science, and Cochrane Library databases. We enrolled primary studies investigating the use of MRI in diagnosing appendicitis in the general adult population, excluding studies that predominantly reported on populations not representative of typical adult appendicitis presentations, such as those focusing on paediatric or pregnant populations.

RESULTS

Twenty-seven eligible primary studies and 6 secondary studies were included, totaling 2,044 patients from eight countries. The sensitivity and specificity of MRI for diagnosing appendicitis were 96% (95% CI: 93-97%) and 93% (95% CI: 80-98%), respectively. MRI can identify complicated appendicitis and accurately propose alternative diagnoses. The duration of MRI protocols in each primary study ranged between 2.26 and 30 minutes, and only one study used intravenous contrast agents in addition to the non-contrast sequences. Decision analysis suggests significant benefits for replacing computed tomography (CT) with MRI and a potential for cost reduction. Reported trends in MRI usage showed minimal utilisation in diagnostic settings even when MRI was available.

CONCLUSIONS

MRI accurately diagnoses appendicitis in the general adult population and improves the identification of complicated appendicitis or alternative diagnoses compared to other modalities using a single, rapid investigation.

Complicated appendicitis in an adult patient

Introduction

Appendicitis is a common cause for emergency operations in the western part of the world, mostly affecting children and young adults. Ultrasound in well-trained hands is an effective imaging tool in making this diagnosis; however, this does not come without its challenges and potential complications.

Case report

This is a case of a 19-year-old male with one-day history of severe pain in the right iliac fossa; blood results showed raised inflammatory markers. Ultrasound revealed a large abnormal loop of bowel containing heterogeneously echogenic contents, and two large appendicoliths at the base and fundus, with the presence of free fluid in the right iliac fossa and oedema in the adjacent mesentery. Laparoscopic appendectomy confirmed the presence of severe appendicitis with generalised peritonitis and appendicolith. Histology revealed gangrenous appendicitis with perforation in two places.

Discussion

This case demonstrates that making a diagnosis of an inflamed appendix alone on ultrasound is not enough, and conducting a detailed assessment of the inflamed appendix and its surrounding anatomy is essential so that all the associated findings can be reported to aid in the patient management, reduce hospital stay and improve overall diagnosis and prognosis.

Magnetic resonance imaging (MRI) for diagnosis of acute appendicitis

BACKGROUND

Appendicitis remains a difficult disease to diagnose, and imaging adjuncts are commonly employed. Magnetic resonance imaging (MRI) is an imaging test that can be used to diagnose appendicitis. It is not commonly regarded as a first-line imaging test for appendicitis, but the reported diagnostic accuracy in some studies is equivalent to computed tomography (CT) scans. As it does not expose patients to radiation, it is an attractive imaging modality, particularly in women and children.

OBJECTIVES

The primary objective was to determine the diagnostic accuracy of MRI for detecting appendicitis in all patients. Secondary objectives: To investigate the accuracy of MRI in subgroups of pregnant women, children, and adults. To investigate the potential influence of MRI scanning variables such as sequences, slice thickness, or field of view.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase until February 2021. We searched the references of included studies and other systematic reviews to identify further studies. We did not exclude studies that were unpublished, published in another language, or retrospective.

SELECTION CRITERIA

We included studies that compared the outcome of an MRI scan for suspected appendicitis with a reference standard of histology, intraoperative findings, or clinical follow-up. Three study team members independently filtered search results for eligible studies.

DATA COLLECTION AND ANALYSIS

We independently extracted study data and assessed study quality using the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2) tool. We used the bivariate model to calculate pooled estimates of sensitivity and specificity.

MAIN RESULTS

We identified 58 studies with sufficient data for meta-analysis including a total of 7462 participants (1980 with and 5482 without acute appendicitis). Estimates of sensitivity ranged from 0.18 to 1.0; estimates of specificity ranged from 0.4 to 1.0. Summary sensitivity was 0.95 (95% confidence interval (CI) 0.94 to 0.97); summary specificity was 0.96 (95% CI 0.95 to 0.97). Sensitivity and specificity remained high on subgroup analysis for pregnant women (sensitivity 0.96 (95% CI 0.88 to 0.99); specificity 0.97 (95% CI 0.95 to 0.98); 21 studies, 2282 women); children (sensitivity 0.96 (95% CI 0.95 to 0.97); specificity 0.96 (95% CI 0.92 to 0.98); 17 studies, 2794 children); and adults (sensitivity 0.96 (95% CI 0.93 to 0.97); specificity 0.93 (95% CI 0.80 to 0.98); 9 studies, 1088 participants), as well as different scanning techniques. In a hypothetical cohort of 1000 patients, there would be 12 false-positive results and 30 false-negative results. Methodological quality of the included studies was poor, and the risk of bias was high or unclear in 53% to 83% of the QUADAS-2 domains.

AUTHORS' CONCLUSIONS

MRI appears to be highly accurate in confirming and excluding acute appendicitis in adults, children, and pregnant women regardless of protocol. The methodological quality of the included studies was generally low due to incomplete and low standards of follow-up, so summary estimates of sensitivity and specificity may be biased. We could not assess the impact and direction of potential bias given the very low number of high-quality studies. Studies comparing MRI protocols were few, and although we found no influence of MRI protocol variables on the summary estimates of accuracy, our results do not rule out that some MRI protocols are more accurate than others.

Abbreviated MRI in patients with suspected acute appendicitis in emergency: a prospective study

PURPOSE

To determine the diagnostic performance of an abbreviated non-contrast MRI protocol in diagnosing acute appendicitis.

METHODS

Prospectively, a total of 67 consenting consecutive patients with clinical suspicion of acute appendicitis (Alvarado score ≥ 5) were evaluated with an abbreviated three-sequence non-contrast MRI protocol (axial T2WI, coronal T2WI, axial DWI) at a single tertiary care center. MRI was interpreted by two radiologists blinded to the clinical details, other investigations, and outcome of the patients. Diagnostic performance of MRI was determined using either histopathological examination (HPE) results as the reference standard in surgical cases (n = 39), or final clinical diagnosis at discharge and 3-months follow-up in non-operatively managed cases (n = 28).

RESULTS

Sixty-seven patients comprising 42 males, 25 females including 1 pregnant patient were enrolled (median age 24 years; age range 6-70 years). The median acquisition duration of the MRI protocol was 12.5 min. In the analysis of the complete cohort including both surgical and non-operatively managed cases (n = 67), MRI showed sensitivity of 93.3% (95% CI 81.7-98.6%), specificity of 86.4% (95% CI 65.1-97.1%), and diagnostic accuracy of 91.0% (95% CI 81.5-96.6%) (p < 0.001). In the subset of surgical cases with HPE as the reference standard (n = 39), MRI showed sensitivity of 97.1% (95% CI 84.7-99.9%), specificity of 100% (95% CI 47.8-100%), and diagnostic accuracy of 98% (95% CI 87.5-100%) (p < 0.001).

CONCLUSION

MRI may be performed to diagnose acute appendicitis or alternative causes of right iliac fossa pain. An abbreviated MRI protocol consisting of only three sequences without IV contrast, patient preparation, or antiperistaltic agents could shorten the examination duration while retaining diagnostic accuracy.

ACR Appropriateness Criteria® Postmenopausal Acute Pelvic Pain

Acute pelvic pain is a common presenting complaint in both the emergency room and outpatient settings. Pelvic pain of gynecologic origin in postmenopausal women occurs less frequently than in premenopausal women; however, it has important differences in etiology. The most common causes of postmenopausal pelvic pain from gynecologic origin are ovarian cysts, uterine fibroids, pelvic inflammatory disease, and ovarian neoplasm. Other etiologies of pelvic pain are attributable to urinary, gastrointestinal, and vascular systems. As the optimal imaging modality varies for these etiologies, it is important to narrow the differential diagnosis before choosing the initial diagnostic imaging examination. Transabdominal and transvaginal ultrasound are the best initial imaging techniques when the differential is primarily of gynecologic origin. CT with intravenous (IV) contrast is more useful if the differential diagnosis remains broad. MRI without IV contrast or MRI without and with IV contrast, as well as CT without IV contrast may also be used for certain differential considerations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Unenhanced MRI of the Abdomen and Pelvis in the Comprehensive Evaluation of Acute Atraumatic Abdominal Pain in Children

OBJECTIVE. The purpose of this study is to show the utility of rapid unenhanced MRI in the comprehensive assessment of acute atraumatic abdominal pain in children, including appendicitis and alternate diagnoses, and to review the MRI features of common acute abdominal and pelvic conditions in a large, single-institution cohort. CONCLUSION. Rapid unenhanced MRI is an excellent option for the initial, comprehensive evaluation of acute abdominal emergencies in pediatric patients because it can diagnose the full range of presenting abnormalities, including causes of abdominal pain warranting surgical and nonsurgical management.

Value Assessment of Evolving Pediatric Appendicitis Imaging Strategies Between 2004 and 2018

OBJECTIVE

To assess diagnostic imaging utilization and the proportion of negative appendectomies for pediatric appendicitis at US children's hospitals between 2004 and 2018.

METHODS

This was a retrospective study using data from the Pediatric Health Information System (PHIS) database. Pediatric patients (age: 0-17 years) who underwent an appendectomy at one of 32 children's hospitals from January 1, 2004, through September 30, 2018, were included. Patients were identified based on International Classification of Diseases, 9th revision and International Classification of Diseases, 10th revision procedure codes. Patient demographics, imaging performed, and the frequency of negative appendectomy were analyzed.

RESULTS

The final study population consisted of 104,033 children. From 2004 to 2018, CT utilization decreased from 56.8% (2,951 of 5,198) to 18.6% (1,201 of 6,455; P < .001). Ultrasound utilization increased from 26.4% (1,371 of 5,198) to 63.4% (4,093 of 6,455; P < .001). Radiography utilization remained stable at 16.7% (870 of 5,198) and 15.8% (1,018 of 6,455; P = .160). MRI use increased from 0.1% (6 of 5,198) to 2.2% (143 of 6,455; P < .001). During the study period, the negative appendectomy rate slightly decreased, from 3.74% (4,742 of 126,778 in 2004-2011) to 3.14% (4,258 of 135,561 in 2012-2018; P < .001).

CONCLUSION

There has been a shift in imaging of children with appendicitis over 15 years in the United States, because the use of CT has decreased and ultrasound use has increased. This shift has likely added value to the health care system without adversely affecting outcomes (negative appendectomy rate).

Utilization of computed tomography imaging in the pediatric emergency department

BACKGROUND

In recent years, there has been a movement toward more judicious use of computed tomography (CT) imaging in an attempt to limit exposure of pediatric patients to ionizing radiation. The Image Gently Alliance and like-minded movements began advocating for safe and high-quality pediatric imaging worldwide in the late 2000s.

OBJECTIVE

In the context of these efforts, we evaluate CT utilization rates in the pediatric emergency department at a major academic medical center.

MATERIALS AND METHODS

We tracked utilization in several categories of CT, magnetic resonance imaging (MRI) and ultrasonography (US) between July 2008 and June 2017 and compared them with utilization rates from 2000 to 2006.

RESULTS

A total of 4,955 pediatric patients underwent a total of 5,973 CT scans, 2,775 US studies and 293 MRI scans while in the pediatric emergency department during the 2008-2017 study period. We observed decreases in CT scans across all categories, ranging from a 19% decrease in abdominal CT to a 66% decrease in chest CT. Relatively greater decreases in CT scans were observed in patients younger than 3 years of age as compared to older children and adolescents. Abdominal and pelvic US increased. Brain MRI also increased over the final two years of the study.

CONCLUSION

CT utilization decreased throughout the 2008-2017 study period.

Are We Doing Enough to Reduce Ionizing Radiation Exposure in Children?: An Analysis of Current Approaches to Pediatric Appendicitis Imaging at a Major Urban Medical Center

OBJECTIVE

The aim of this study was to evaluate current imaging approaches in children with suspected appendicitis (AP) in the pediatric emergency department (ED) of a major urban medical center.

METHODS

Children aged 6 to 18 years who presented to a pediatric ED in 2016 with possible AP were identified by a keyword search. Charts were reviewed for the following: age, sex, time of evaluation, imaging study, results of imaging study, disposition, and outcome.

RESULTS

We calculated mean values and SD for continuous data. Initially, 503 charts were identified. Of these 503, 292 children were identified as having possible AP. Mean age was 10.7 years (SD, 2.7); 50.6% presented between 5:00 PM and 8:00 AM the next morning. Of the 287 US studies performed, 114 (39.7%) were definitively positive or negative. Of these, 46 (16.0%) were negative for AP and 68 (23.7%) were positive. There were 173 (60.3%) ultrasounds that were equivocal. Computed tomography scans were performed in 41 (13.9%) of the total 292 patients, and 2 (0.7%) of the 292 received magnetic resonance imaging. Patient dispositions were as follows: discharged home, 163 (55.8%); admitted for appendectomy, 69 (23.6%); admitted for observation, 37 (12.7%); and extended observation in ED, 10 (3.4%). There were 83 (28.4%) total surgical and interventional radiology cases and 209 (71.6%) nonsurgical cases. Of the 81 appendectomies, 79 (97.5%) had an abnormal appendix, and 2 (2.5%) had no AP. Of the 79 abnormal appendices, 22 (27.8%) were perforated, 55 (69.6%) were not, and 2 (2.6%) were unclear.

CONCLUSIONS

Computed tomography scans were performed in 13.9% of patients with suspected AP. The overall AP rate was 28.4%. We plan to increase the use of magnetic resonance imaging and other modalities to reduce overall computed tomography usage.

Accuracy, criteria, and clinical significance of visual assessment on diffusion-weighted imaging and apparent diffusion coefficient quantification for diagnosing acute appendicitis

PURPOSE

To assess the accuracy, criteria, and clinical significance of diffusion-weighted imaging (DWI) signal intensity and apparent diffusion coefficient (ADC) quantification for diagnosing acute appendicitis.

METHODS

Fifty-one patients with right lower abdominal pain [uncomplicated appendicitis (n = 25), complicated appendicitis (n = 10), and non-appendicitis (n = 16)] who underwent MR examination were enrolled in this retrospective study. Two radiologists independently measured appendiceal diameter and wall thickness. They assessed whether a wall defect, an abscess, extraluminal air, or an appendicolith was present on axial T2WI; evaluated intensity on DWI using a 5-point scale; and determined the ADC values of the appendix and peri-appendiceal tissue. Statistical analysis was performed to assess imaging findings for the diagnosis of appendicitis and complicated appendicitis. Cut-off values were determined using receiver operating characteristic analysis.

RESULTS

For diagnosing acute appendicitis, the accuracy improved from 78.4% using only T2WI to 86.3% using combined T2WI and DWI for reader 1 and from 82.4 to 86.3% for reader 2. For the appendix, the cut-off ADC values that diagnosed appendicitis were 1.41 × 10^-3 and 1.26 × 10^-3 mm²/s with accuracies of 78.4% and 76.5%, respectively. For the peri-appendiceal tissue, these values of 1.03 × 10^-3 and 0.91 × 10^-3 mm²/s differentiated between uncomplicated and complicated appendicitis with an accuracy of 97.1%.

CONCLUSIONS

Combined DWI and T2WI provided high accuracy for diagnosing appendicitis. The inflamed appendix had lower ADC value than the normal appendix. The peri-appendiceal tissue presenting low ADC value was a notable finding of complicated appendicitis.

Perforation risk in pediatric appendicitis: assessment and management

Perforated appendicitis, as defined by a visible hole in the appendix or an appendicolith free within the abdomen, carries significant morbidity in the pediatric population. Accurate diagnosis is challenging as there is no single symptom or sign that accurately predicts perforated appendicitis. Younger patients and those with increased duration of symptoms are at higher risk of perforated appendicitis. Elevated leukocytosis, bandemia, high C-reactive protein, hyponatremia, ultrasound, and CT are all useful tools in diagnosis. Distinguishing patients with perforation from those without is important given the influence of a perforation diagnosis on the management of the patient. Treatment for perforated appendicitis remains controversial as several options exist, each with its indications and merits, illustrating the complexity of this disease process. Patients may be managed non-operatively with antibiotics, with or without interval appendectomy. Patients may also undergo appendectomy early in the course of their index hospitalization. Factors known to predict failure of non-operative management include appendicolith, leukocytosis greater than 15,000 white blood cells per microliter, increased bands, and CT evidence of disease beyond the right lower quadrant. In this review, the indications and benefits of each treatment strategy will be discussed and an algorithm to guide treatment decisions will be proposed.