Diagnostic utility of intravenous contrast for MR imaging in 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.

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.

Acute care diagnostics in children for general radiologists - not alone in the hospital at night

BACKGROUND

Radiologic care for children and adolescents during night and weekend shifts is challenging. This is especially true when a dedicated pediatric radiology front or background service is not available.

METHODS

The purpose of this review is to present the approach, the most relevant diagnoses, and their differential diagnoses based on four common example cases - abdominal pain, respiratory/chest pain, headache, and refusal to walk. Essentials such as clinical classification (e. g., disease dynamics) and practical instructions (e. g., necessity of acute cross-sectional imaging) are presented.

RESULTS AND CONCLUSION

For the abdomen, appendicitis ranks first among acute diseases. Other important diseases are intussusception and volvulus. Far more frequently, however, gastroenteritis is the cause of abdominal pain. Usually no imaging is required in this case. In unclear clinical situations, ultrasound may be indicated. In suspected pulmonary infections, chest imaging is limited to inconclusive cases and suspicion of complications such as pleural empyema. Major emergencies include (spontaneous) pneumothorax and aspiration. Headache is a common symptom. Immediate imaging is only necessary in cases of suspected acute inflammatory (meningitis/encephalitis) or vascular disease (e. g., hemorrhage due to vascular malformations). MRI is the primary imaging modality in these cases. Restricted walking/refusal to walk is a classic nonspecific sign, particularly of acute musculoskeletal disease, especially in younger children. Clinical examination is essential to narrow down the field of investigation. Besides the frequent and symptomatic coxitis fugax, the rare but serious (septic) arthritis/osteomyelitis must not be overlooked.

KEY POINTS

· Radiological care of children and adolescents is challenging, especially during night and weekend shifts.. · However, in close cooperation with the referring colleagues/clinics, the appropriate approach can be effectively determined even if the symptoms are not clear.. · The selection of the optimal imaging method is based on guidance and guidelines, but also on the condition of the child/adolescent.. · A silent or whimpering child is cause for alarm..

CITATION FORMAT

· Beer M, Mentzel H, Steinborn M et al. Acute care diagnostics in children for general radiologists - not alone at night in the hospital. Fortschr Röntgenstr 2023; 195: 205 - 216.

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.

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.

Fast acquisition abdominal MRI study for the investigation of suspected acute appendicitis in paediatric patients

Objectives

To assess the diagnostic accuracy of fast acquisition MRI in suspected cases of paediatric appendicitis presenting to a tertiary referral hospital.

Materials and methods

A prospective study was undertaken between May and October 2017 of 52 children who presented with suspected appendicitis and were referred for an abdominal ultrasound. All patients included in this study received both an abdominal ultrasound and five-sequence MRI consisting of axial and coronal gradient echo T2 scans, fat-saturated SSFSE and a diffusion-weighted scan. Participants were randomised into groups of MRI with breath-holds or MRI with free breathing. A patient satisfaction survey was also carried out. Histopathology findings, where available, were used as a gold standard for the purposes of data analysis. Statistical analysis was performed, and p values < 0.05 were considered statistically significant.

Results

Ultrasound had a sensitivity and specificity of 25% and 92.9%, respectively. MRI with breath-hold had a sensitivity and specificity of 81.8% and 66.7%, respectively, whilst MRI with free breathing was superior with sensitivity and specificity of 92.3% and 84.2%, respectively. MRI with free breathing was also more time efficient (p < 0.0001). Group statistics were comparable (p < 0.05).

Conclusions

The use of fast acquisition MRI protocols, particularly free breathing sequences, for patients admitted with suspected appendicitis can result in faster diagnosis, treatment and discharge. It also has a statistically significant diagnostic advantage over ultrasound. Additionally, the higher specificity of MR can reduce the number of negative appendectomies performed in tertiary centres.

Falling through the worm hole: an exploration of the imaging workup of the vermiform appendix in the pediatric population

Despite the thousands of articles discussing appendicitis in the literature, the dilemma of how to best diagnosis and manage pediatric appendicitis remains unsettled. Over the past decade, evidence has been mounting about the use of antibiotics as the sole therapy in uncomplicated appendicitis in the adult population. This debate has even recently bled over into the lay press. While this change in practice pattern is still in its infancy for the pediatric population, radiologists should be aware of this change in therapy and how it can impact the imaging work-up and relevant findings. This article concisely summarizes the imaging findings and various imaging pathways to arrive at the diagnose of appendicitis with an emphasis of how to best be of use to our surgical colleagues in this evolving paradigm. It also highlights venues for further research, namely increasing accuracy of differentiating complicated from uncomplicated appendicitis.

Visualization of the normal appendix in children: feasibility of a single contrast-enhanced radial gradient recalled echo MRI sequence

BACKGROUND

Magnetic resonance imaging (MRI) assessment for appendicitis is limited by exam time and patient cooperation. The radially sampled 3-dimensional (3-D) T1-weighted, gradient recalled echo sequence (radial GRE) is a free-breathing, motion robust sequence that may be useful in evaluating appendicitis in children.

OBJECTIVE

To compare the rate of detection of the normal appendix with contrast-enhanced radial GRE versus contrast-enhanced 3-D GRE and a multi-sequence study including contrast-enhanced radial GRE.

MATERIALS AND METHODS

This was a retrospective study of patients ages 7-18 years undergoing abdominal-pelvic contrast-enhanced MRI between Jan. 1, 2012, and April 1, 2016. Visualization of the appendix was assessed by consensus between two pediatric radiologists. The rate of detection of the appendix for each sequence and combination of sequences was compared using a McNemar test.

RESULTS

The rate of detection of the normal appendix on contrast-enhanced radial GRE was significantly higher than on contrast-enhanced 3-D GRE (76% vs. 57.3%, P=0.003). The rate of detection of the normal appendix with multi-sequence MRI including contrast-enhanced radial GRE was significantly higher than on contrast-enhanced 3-D GRE (81.3% vs. 57%, P<0.001). There was no significant difference between the rate of detection of the normal appendix on contrast-enhanced radial GRE alone and multi-sequence MRI including contrast-enhanced radial GRE (76% vs. 81.3%, P=0.267).

CONCLUSION

Contrast-enhanced radial GRE allows superior detection of the normal appendix compared to contrast-enhanced 3-D GRE. The rate of detection of the normal appendix on contrast-enhanced radial GRE alone is nearly as good as when the contrast-enhanced radial GRE is interpreted with additional sequences.

Utility of applying white blood cell cutoffs to non-diagnostic MRI and ultrasound studies for suspected pediatric appendicitis

BACKGROUND

Non-contrast magnetic resonance imaging (MRI) and ultrasound studies in pediatric patients with suspected appendicitis are often non-diagnostic. The primary objective of this investigation was to determine if combining these non-diagnostic imaging results with white blood cell (WBC) cutoffs improves their negative predictive values (NPVs).

METHODS

A retrospective chart review was conducted including patients ≤18 years old with suspected appendicitis who had MRI performed with or without a preceding ultrasound study in a pediatric emergency department. Imaging results were sorted into 2 diagnostic and 5 non-diagnostic categories. NPVs were calculated for the non-diagnostic MRI and ultrasound categories with and without combining them with WBC cutoffs of <10.0 and <7.5 × 10⁹/L.

RESULTS

Of the 612 patients with MRI studies included, 402 had ultrasound studies performed. MRI with incomplete visualization of a normal appendix without secondary signs of appendicitis had an NPV of 97.9% that changed to 98.1% and 98.2% when combined with WBC cutoffs of <10.0 and <7.5, respectively. Ultrasound studies with incomplete visualization of a normal appendix without secondary signs had an NPV of 85.3% that improved to 94.8% and 96.5% when combined with WBC cutoffs of <10.0 and <7.5, respectively.

CONCLUSIONS

In pediatric patients with suspected appendicitis, MRI studies with incomplete visualization of a normal appendix without secondary signs have a high NPV that does not significantly change with the use of these WBC cutoffs. In contrast, combining WBC cutoffs with ultrasound studies with the same interpretation identifies low-risk groups.

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.

Differentiating perforated from non-perforated appendicitis on contrast-enhanced magnetic resonance imaging

BACKGROUND

The role of magnetic resonance imaging (MRI) in pediatric appendicitis is increasing; MRI findings predictive of appendiceal perforation have not been specifically evaluated.

OBJECTIVE

To assess the performance of MRI in differentiating perforated from non-perforated appendicitis.

MATERIALS AND METHODS

A retrospective review of pediatric patients undergoing contrast-enhanced MRI and subsequent appendectomy was performed, with surgicopathological confirmation of perforation. Appendiceal diameter and the following 10 MRI findings were assessed: appendiceal restricted diffusion, wall defect, appendicolith, periappendiceal free fluid, remote free fluid, restricted diffusion within free fluid, abscess, peritoneal enhancement, ileocecal wall thickening and ileus. Two-sample t-test and chi-square tests were used to analyze continuous and discrete data, respectively. Sensitivity and specificity for individual MRI findings were calculated and optimal thresholds for measures of accuracy were selected.

RESULTS

Seventy-seven patients (mean age: 12.2 years) with appendicitis were included, of whom 22 had perforation. The perforated group had a larger mean appendiceal diameter and mean number of MRI findings than the non-perforated group (12.3 mm vs. 8.6 mm; 5.0 vs. 2.0, respectively). Abscess, wall defect and restricted diffusion within free fluid had the greatest specificity for perforation (1.00, 1.00 and 0.96, respectively) but low sensitivity (0.36, 0.25 and 0.32, respectively). The receiver operator characteristic curve for total number of MRI findings had an area under the curve of 0.92, with an optimal threshold of 3.5. A threshold of any 4 findings had the best ability to accurately discriminate between perforated and non-perforated cases, with a sensitivity of 82% and specificity of 85%.

CONCLUSION

Contrast-enhanced MRI can differentiate perforated from non-perforated appendicitis. The presence of multiple findings increases diagnostic accuracy, with a threshold of any four findings optimally discriminating between perforated and non-perforated cases. These results may help guide management decisions as MRI assumes a greater role in the work-up of pediatric appendicitis.