Effectiveness of a Staged US and Unenhanced MR Imaging Algorithm in the Diagnosis of Pediatric Appendicitis

Characterization and quantification of fluid in the abdomen by ultrasound and magnetic resonance imaging in children with clinical suspicion of appendicitis

PURPOSE

While regarded as a secondary sign of pediatric appendicitis, the frequency of physiologic intra-abdominal fluid in children with suspected but absent appendicitis is unknown. Ex vivo: to assess the validity of US/MRI measurements of free fluid. In vivo: in suspected pediatric appendicitis, to assess the amount of abdominal fluid by US and MRI, determine performance characteristics of US in fluid detection and identify fluid volume ranges in confirmed appendicitis.

METHODS

Ex vivo: criterion validity of US and MRI for fluid volume measurements was tested using tissue-mimicking phantoms filled with different volumes of distilled water. In vivo: all participants from a previous prospective study of suspected appendicitis were evaluated by US; MRI was performed after equivocal USs. Qualitative and quantitative analyses of abdominal fluid and correlation of fluid presence with appendicitis were performed.

RESULTS

Ex vivo: no difference was found between phantom-fluid amount and measured volume using the formula for volume of an ellipsoid for US (P=0.19) or MRI (P=0.08). In vivo: intra-abdominal fluid was present in 212/591 (35.9%) patients; 75/212 patients with fluid (35.4%) had appendicitis, 60 (28.3%) had alternate diagnoses, and 77 (36.3%) had physiologic fluid. Sensitivity and specificity of US for fluid detection were 84% (95% CI 71-93) and 65% (95% CI 52-77), respectively. In children with versus without appendicitis, the respective ranges of fluid volume were 0.7-1148.8 ml and 0.8-318 ml.

CONCLUSION

The volume of an ellipsoid formula is a valid method for quantifying intra-abdominal fluid. The sole presence of intra-abdominal fluid on US does not support the diagnosis of pediatric appendicitis.

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.

Properties of ultrasound-rapid MRI clinical diagnostic pathway in suspected pediatric appendicitis-A prospective cohort study

OBJECTIVE

to determine diagnostic accuracy of an US-MRI clinical diagnostic pathway to detect appendicitis in the emergency department (ED).

STUDY DESIGN

prospective cohort study of 624 previously healthy children 4-17 years old undergoing US for suspected appendicitis and clinical re-assessment. Children with non-diagnostic USs and persistent appendicitis concern/conclusive US-reassessment discrepancies underwent ultra-rapid MRI (US-MRI pathway), interpreted as positive, negative or non-diagnostic. Cases with missed appendicitis, negative appendectomies, and CT utilization were considered clinically diagnostically inaccurate. Primary outcome was the proportion of accurate diagnoses of appendicitis/lack thereof by the pathway.

RESULTS

150/624 (24%) children had appendicitis;255 USs (40.9%) were non-diagnostic. Of 139 US-MRI pathway children (after 117 non-diagnostic and 22 conclusive USs), 137 [98.6%; 95% CI 0.96-1.00] had clinically accurate outcomes (1 CT, 1 negative appendectomy): sensitivity 18/18 [100%], specificity 119/121 [98.3%], positive predictive value 18/20 [90.5%], negative predictive value 119/119 [100%]. MRI imaging accuracy was 134/139 (96.4%); 3 MRIs were non-diagnostic (no appendicitis). In the overall algorithm, 616/624 [98.7% (0.97-0.99)] patients had accurate outcomes: 147/150 (98.0%) appendicitis cases had confirmatory surgeries (3 CTs) and 469/474 (98.9%) appendicitis-negative children had no surgery/CT.

CONCLUSION

this study demonstrated high clinical accuracy of the US-rapid-MRI pathway in suspected pediatric appendicitis after non-diagnostic US.

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.

Comparison of MRI appendix biometrics in children with and without acute appendicitis

OBJECTIVES

The goal of this study is to improve MRI-specific diagnostic criteria for pediatric appendicitis through comparison of normal and abnormal appendix-related imaging features.

METHODS

A retrospective multireader-multicase design was used, including non-contrast MRI performed for suspected pediatric appendicitis following non-diagnostic US from January 2014 to December 2017. Positive diagnosis was defined by surgical pathology or symptom resolution after antibiotics. Four pediatric radiologists independently graded study biometrics while blinded to clinical data. Balanced complete block design was used to determine performance characteristics.

RESULTS

Global diagnosis of appendicitis (208 studies) had sensitivity 90.6% and specificity 97.7%. Median appendix diameter was 10.4 mm among positive cases and 5.8 mm among negative cases (p < 0.001) with an optimal diagnostic cutoff of 7.5 mm (sensitivity 89.4%, specificity 86.5%). Median appendix wall thickness was 2.6 mm among positive cases and 1.7 mm among negative cases (p < 0.001) with an optimal diagnostic cutoff of 2.3 mm (sensitivity 63.1%, specificity 82.9%). Performance characteristics for qualitative appendix features included distinguishable appendix luminal signal (sensitivity 89.6%, specificity 83.7%), intraluminal fluid-signal intensity (sensitivity 63.6%; specificity 52.3%), intraluminal signal intermediate between fluid and bowel wall (sensitivity 91.0%; specificity 37.1%), appendicolith (sensitivity 34.9%; specificity 100.0%), intraluminal layering (sensitivity 25.9%; specificity 100.0%), hyperintense appendix wall signal (sensitivity 31.7%; specificity 100.0%), periappendiceal fluid (sensitivity 66.8%; specificity 72.5%), periappendiceal fatty edema (sensitivity 91.3%; specificity 94.5%), and free pelvic fluid (sensitivity 88.5%; specificity 26.0).

CONCLUSIONS

This study provides MRI-specific performance of pediatric appendicitis quantitative and qualitative biometrics with peri-appendiceal fatty edema, appendix diameter > 7.5 mm, and distinguishable appendix luminal signal demonstrating the highest overall accuracy.

KEY POINTS

• This retrospective multireader-multicase study characterized magnetic resonance imaging-specific diagnostic accuracy of quantitative and qualitative biometrics for pediatric appendicitis. • The optimal quantitative diagnostic thresholds for an abnormal pediatric appendix at MRI included diameter and wall thickness of 7.5 mm and 2.3 mm, respectively. • Qualitative imaging biometrics with high specificity for pediatric appendicitis on MRI included the presence of distinguishable appendix lumen signal from wall signal, appendicolith, intraluminal fluid-fluid layer, appendix wall hyperintensity, and peri-appendiceal fatty edema.

Ultrasonographic findings of child acute appendicitis incorporated into a scoring system

INTRODUCTION

This study aimed to investigate the ultrasonographic features of child acute appendicitis and incorporate them into a scoring algorithm that will quantify the risk of complications and the strength of recommendation for surgical intervention.

METHODS

179 patients with suspected appendicitis and who had undergone ultrasonographic examination were included in this study. Based on their medical evaluation and post-surgical histopathological results, patients were categorised into the confirmed appendicitis (n = 101); and non-appendicitis (n = 78) groups.

RESULTS

In the appendicitis group, the appendix was visualised in 66 (65.3%) patients. In cases where the appendix was not visualised, we looked out for secondary inflammatory signs, which were present in 32 (31.7%) patients. Using stepwise logistic regression, Blumberg's sign, free fluid or collection, hyperaemia, non-compressible appendix and an appendix diameter > 7 mm were found to be significant predictive factors for appendicitis. A new scoring system called POPs was developed, combining inflammatory predictors and ultrasonography findings, with an area under the receiving operating characteristic curve of 0.958 (95% confidence interval 0.929-0.986).

CONCLUSION

The newly developed POPs-based diagnosis scheme proved a promising alternative to existing scoring systems, such as the Alvarado score. Although further calibration would be beneficial, the proposed scoring scheme is simple and easy to understand, memorise and apply in the emergency room.

Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines

BACKGROUND AND AIMS

Acute appendicitis (AA) is among the most common causes of acute abdominal pain. Diagnosis of AA is still challenging and some controversies on its management are still present among different settings and practice patterns worldwide. In July 2015, the World Society of Emergency Surgery (WSES) organized in Jerusalem the first consensus conference on the diagnosis and treatment of AA in adult patients with the intention of producing evidence-based guidelines. An updated consensus conference took place in Nijemegen in June 2019 and the guidelines have now been updated in order to provide evidence-based statements and recommendations in keeping with varying clinical practice: use of clinical scores and imaging in diagnosing AA, indications and timing for surgery, use of non-operative management and antibiotics, laparoscopy and surgical techniques, intra-operative scoring, and peri-operative antibiotic therapy.

METHODS

This executive manuscript summarizes the WSES guidelines for the diagnosis and treatment of AA. Literature search has been updated up to 2019 and statements and recommendations have been developed according to the GRADE methodology. The statements were voted, eventually modified, and finally approved by the participants to the consensus conference and by the board of co-authors, using a Delphi methodology for voting whenever there was controversy on a statement or a recommendation. Several tables highlighting the research topics and questions, search syntaxes, and the statements and the WSES evidence-based recommendations are provided. Finally, two different practical clinical algorithms are provided in the form of a flow chart for both adults and pediatric (< 16 years old) patients.

CONCLUSIONS

The 2020 WSES guidelines on AA aim to provide updated evidence-based statements and recommendations on each of the following topics: (1) diagnosis, (2) non-operative management for uncomplicated AA, (3) timing of appendectomy and in-hospital delay, (4) surgical treatment, (5) intra-operative grading of AA, (6) ,management of perforated AA with phlegmon or abscess, and (7) peri-operative antibiotic therapy.

Bowel Imaging in Children: Part 2

The bowel is a challenging abdominal organ to image. A variety of bowel disorders such as congenital, developmental, inflammatory, infectious and neoplastic lesions can affect children and most of them are either unique to this age group or have a distinct clinico-radiological appearance compared to adults. Imaging forms an integral part of management of these disorders. This article will cover inflammatory/infective, neoplastic and miscellaneous disorders affecting the bowel. The authors will highlight the salient imaging features for those entities.

Diagnosis of appendicitis in the paediatric emergency department: an update

PURPOSE OF REVIEW

Concern regarding appendicitis is a common reason for presentation to the paediatric emergency department. We review recent progress in the use of biomarkers, imaging and clinical scoring systems in improving diagnostic accuracy in suspected appendicitis in children.

RECENT FINDINGS

Use of ultrasound, often performed at the bedside, is becoming more widespread with a parallel reduction in computed tomography (CT) use. Protocols for image acquisition and interpretation have been shown to improve diagnostic accuracy. Novel biomarkers have been explored and clinical diagnostic algorithms refined but none have achieved the level of diagnostic accuracy required.

SUMMARY

Appendicitis remains a clinical diagnosis. Point of care ultrasound is increasingly available and offers higher diagnostic accuracy than several routinely performed laboratory investigations. Recent publications provide support for increased use of clinician performed ultrasound, increased use of MRI, less use of CT, less emphasis on basic laboratory investigation and a renewed respect for the value of serial examination, particularly early in the course of illness.

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.

Practical Imaging Strategies for Acute Appendicitis in Children

OBJECTIVE

Diagnosing pediatric appendicitis is difficult because clinical findings are nonspecific. Improved accuracy can be obtained with ultrasound (US), CT, or MRI, despite considerable variation in their use at different institutions. This article reviews the evidence for best practices in imaging pediatric appendicitis.

CONCLUSION

When each modality is optimally used, a stepwise imaging approach that begins with graded compression US and proceeds to CT or MRI in select cases is currently best practice.

Improving diagnostic accuracy in clinically ambiguous paediatric appendicitis: a retrospective review of ultrasound and pathology findings with focus on the non-visualised appendix

OBJECTIVE

To compare pre-operative ultrasound to histopathological results and retrospectively assess the diagnostic accuracy of ultrasound in paediatric appendicitis.

METHODS

5 year review of all appendectomies performed in patients <16 years old in a tertiary referral university hospital. 983 patients had an appendicectomy over the time period while 189 patients had a preoperative ultrasound. We retrospectively reviewed all of the preoperative imaging in conjunction with the reports for the 189 patients; our aim was to determine the sensitivity of preoperative ultrasound for the diagnosis of acute appendicitis.

RESULTS

Of the 189 patients who had an ultrasound, 102 had histology positive for appendicitis and 87 had normal histology. Sensitivity overall was 72.55% [95% confidence interval (CI) 62.82 to 80.92] and specificity was 77.01% (95% CI 66.75 to 85.36). A suggested ultrasound diagnosis of appendicitis made positive pathology three times more likely and a normal ultrasound made positive pathology three times less likely [positive-predictive value 3.16 (95% CI 2.11 to 4.72) negative predictive value 0.36 (95% CI 0.25 to 0.50)]. 77% (67/87) of the patients whose pathology was ultimately normal had an ultrasound which was either normal or suggested an alternative diagnosis. However, in the 33 (17%) of patients with a non-visualised appendix, no secondary signs of inflammation or alternative diagnosis 16 (48%) had pathologically confirmed appendicitis.

CONCLUSION

Ultrasound has the potential to improve diagnostic accuracy in clinically ambiguous appendicitis.

ADVANCES IN KNOWLEDGE

This paper furthers the evidence on the efficacy of ultrasound as a diagnostic tool in acute appendicitis in children, especially when the diagnosis is clinically equivocal. It also sheds further light on the "non-visualized appendix" with almost half of these patients having pathologically confirmed appendicitis; meaning advanced imaging with CT or MR may be indicated in this cohort.