Clinical impact and cost‐effectiveness of noncontrast MRI in the evaluation of suspected appendiceal abscesses in children

A Magnetic Resonance Imaging Protocol for the Evaluation of Pediatric Postappendectomy Abscess: A Quality Improvement Project

INTRODUCTION

Computed tomography (CT) scans are often used when cross-sectional imaging is required for evaluation of postappendectomy abscess, exposing children to a source of ionizing radiation. Our aim was to decrease the use of CT scans in pediatric postappendectomy patients by 50% in 12 mo and to sustain those results for 1 y.

METHODS

A comprehensive magnetic resonance imaging protocol was introduced in 2018 at a tertiary children's hospital within a general health system to replace CT scans in suspected pediatric postappendectomy abscess. Diagnostic and clinical outcomes were compared preprotocol (2015-2017) and postprotocol (2018-2022) implementation using standard univariate statistics. P < 0.05 was considered significant. Quality improvement methodology was used to design and implement the protocol.

RESULTS

Sixty eight pediatric postappendectomy patients received cross-sectional imaging during the study period. Overall, CT scans were used exclusively (100%, n = 27) in the preimplementation period compared to 31.7% (n = 13) of cross-sectional imaging in the postimplementation period. However, in the first year of protocol implementation, CT scan use only decreased to 78% of cross-sectional studies performed. The majority of protocol deviations (54%) also occurred in this time period. With improved education and reinforcement, CT scan utilization decreased to approximately 24% of cross-sectional studies annually. Missed abscess rate, time to diagnosis, drainage procedure type, readmission, and reoperation were similar between preimplementation and postimplementation periods.

CONCLUSIONS

Implementation of a postappendectomy abscess magnetic resonance imaging protocol was associated with decreased CT utilization in the pediatric population, while maintaining comparable diagnostic evaluation and clinical outcomes. Adherence to quality improvement principles facilitated achieving goals and sustaining gains.

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.

Image-guided abscess drainage in children with perforated appendicitis - can it wait?

BACKGROUND

Image-guided drainage is the management of choice for perforated appendicitis with intra-abdominal abscess/es. However, there is paucity of data regarding the optimal time for intervention in children.

OBJECTIVE

The purpose of this study is to assess the relationship between the time from diagnosis of a drainable abscess to abscess drainage (delta time) and the clinical outcome in patients with complicated acute appendicitis.

MATERIALS AND METHODS

This is an institutional review board (IRB)-approved retrospective study comprising 80 pediatric patients who had image-guided abscess drainage due to perforated acute appendicitis. Delta time was associated with clinical outcome including length of stay, catheter dwell time, need for additional interventions, and need for tissue plasminogen activator (t-PA). Gamma regression models were used to assess the adjusted effect of delta time on the "length of stay" and "catheter dwell time" using "volume of the largest abscess" and "number of collections" as severity indices. Logistic regression was used to assess the effect of delta time on the "need for the t-PA" and "need for additional interventions."

RESULTS

Mean age (SD) was 10.2 (3.8) years. Mean time between diagnosis and intervention (delta time) was 1.5 (1.2) days. There was no evidence that delta time effects the length of stay, catheter dwell time, need for t-PA, and need for additional interventions (P > 0.05). However, there was an association between the number of collections and volume of the largest abscess with length of stay (P = 0.006; P = 0.058), catheter dwell time (P = 0.029; P < 0.001), and need for additional interventions (P = 0.029; P = 0.016).

CONCLUSIONS

Our results suggest that time between diagnosis of an appendicitis associated abscess and intervention is not significantly associated with need for tPA, need for additional intervention, drain dwell time, or length of stay.

Can magnetic resonance imaging replace computed tomography scans in the evaluation of pediatric post-appendectomy abscess?

BACKGROUND

Computed tomography scans have been used when cross-axial imaging is required to evaluate pediatric post-appendectomy abscesses. To reduce a source of radiation exposure, our institution converted to using contrast-enhanced magnetic resonance imaging to replace computed tomography scans in this clinical context. Our aim is to evaluate the performance of magnetic resonance imaging compared to computed tomography scans and associated clinical outcomes in this patient population.

METHODS

A contrast-enhanced comprehensive magnetic resonance imaging protocol was implemented to evaluate a post-appendectomy abscess in 2018. A retrospective chart review was performed from 2015 to 2022 for pediatric patients (<18 years old) with prior appendectomy and subsequent cross-sectional imaging to evaluate for an intraabdominal abscess. Patient characteristics and clinical parameters between the 2 modalities were abstracted and compared using standard univariate statistics.

RESULTS

There were a total of 72 post-appendectomy patients who received cross-axial imaging, which included 43 computed tomography scans and 29 magnetic resonance imaging during the study interval. Patient demographics were comparable between cohorts and rates of perforated appendicitis at the index operation (computed tomography: 79.1% vs magnetic resonance imaging: 86.2%). Missed abscess rate, abscess size, management technique, drainage culture results, readmission, and reoperation were similar between imaging modalities. Median request to scan time was longer for magnetic resonance imaging than computed tomography (191.5 vs 108 minutes, P = .04). The median duration of a comprehensive magnetic resonance imaging scan was 32 minutes (interquartile range 28-50.5 minutes).

CONCLUSION

Contrast-enhanced magnetic resonance imaging provides an alternative cross-sectional imaging modality to computed tomography scans to evaluate pediatric post-appendectomy abscesses.

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.

"Quick" MRIs without contrast in the setting of pediatric abscess drainage: A comparative analysis of clinical outcomes

BACKGROUND/PURPOSE

To assess the use of "quick" MRI without contrast in the setting of percutaneous drain management in pediatric patients.

METHODS

A retrospective medical record review was conducted to compare "quick" MRI without contrast to CT in the pediatric percutaneous drain placement setting. The study included 111 patients under 18-years-old having undergone percutaneous drain placement between January 2014 and January 2019. The "quick" MRI protocol consists of axial single-shot-fast-spin-echo (SSFSE) and fat-saturated SSFSE coronal sequences. Primary clinical outcomes included number of additional drain placement procedures, complications, length of hospitalization, and repeat drainage within 6 months following drain-free interval. The use of "quick" MRI post-procedurally was also investigated.

RESULTS

Patients with pre-drain "quick" MRIs instead of CTs had no significant difference in the need for additional drain placement (p = 1), length of hospitalization (p = 0.275), or drainage complications (p = 0.728). Patients receiving "quick" MRI for follow-up imaging post-drain placement had no greater rate of repeat drainage within 6 months of initial drain discontinuation (p = 0.90) when compared to patients having CT.

CONCLUSIONS

Pre and post-drainage procedure "quick" MRIs were found to be equivalent to CT in regard to several key clinical outcomes.