Magnetic resonance imaging (MRI) for diagnosis of acute appendicitis

Utility of thiol/disulphide homeostasis as a biomarker for acute appendicitis: a systematic review and meta-analysis

The aim of this study was to analyze the role of thiol/disulfide homeostasis (TDH) parameters as an indicator of oxidative stress in acute appendicitis (AA). PubMed, EMBASE, Web of Science, and Scopus databases were systematically searched. Studies reporting on TDH in AA (both complicated and uncomplicated cases) were included. The comparator group were healthy controls. The TDH domain was compared between the groups using anti-oxidant parameters, namely native thiol and total thiol levels, and native thiol/total thiol ratio; and oxidant parameters, namely disulfide level, disulfide/native thiol ratio, and disulfide/total thiol ratio. The statistical analysis was performed using a random-effects model. The methodological quality of the studies was assessed utilizing the Newcastle-Ottawa scale. Eleven studies with a total of 926 subjects, comprising 457 patients with uncomplicated appendicitis, 147 with complicated appendicitis, and 322 healthy controls were included. Our study demonstrated significantly increased oxidative stress in AA as compared to healthy controls in all TDH parameters and significantly lower total thiol levels in complicated AA as compared to uncomplicated AA. Due to a poor methodological quality in five out of eleven studies, future prospective studies with adequate power are essential to validate these observations and refine the diagnostic approaches to AA.

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.

The Effect of Preoperative Imaging on the Negative Appendicectomy Rate

Background Appendicitis is one of the most common causes of acute abdominal pain and appendicectomy is one of the most frequently performed surgical procedures. The proliferation of radiological imaging has reduced the number of patients who have a normal appendix removed, i.e., a negative appendicectomy. We aimed to assess the effect of preoperative imaging on the negative appendicectomy rate (NAR). Methodology All emergency appendicectomies performed at a district general hospital in the United Kingdom over two separate one-year periods were retrospectively analysed using emergency theatre log books. The timeframes were chosen based on the introduction of a diagnostic pathway to reduce the number of appendicectomies performed on patients later found not to have appendicitis or alternative abnormality, i.e., a negative appendicectomy. This pathway involved a greater emphasis placed on preoperative imaging (CT or ultrasound) for patients with suspected appendicitis. The study excluded any patients who were found to have an alternative pathology during surgery. Information technology databases were used to collect data on patient demographics, date of surgery, histology, and any preoperative imaging that was performed. All histological findings showing acutely inflamed appendices and those positive for malignancy were categorised as positive, whereas all other findings were categorised as negative. Results During our initial data collection period (April 2018 to April 2019), we collected data on 207 patients who underwent an appendicectomy. The NAR was 17%. During our subsequent data collection period (August 2020 to August 2021), we collected data on 184 patients. The NAR was 16%. In our adult population, the NAR decreased from 13% to 9%. Discussion At first glance, the NAR does not seem to have improved. On closer look, all patients over the age of 21 years in our re-audit underwent pr-operative CT, and there was a reduction in the NAR in these patients. The issue arises with younger patients, in whom justifying the radiation associated with a CT scan may be difficult. Although ultrasound does not carry the same radiation risk, previous audits at our trust have that shown its sensitivity and specificity for appendicitis is approximately 60%. We may have to explore alternative imaging modalities such as MRI in the paediatric population or accept the higher NAR.

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.

Diagnostic accuracy of ultrasound in the paediatric population with acute right iliac fossa pain, our District General Hospital experience

AIM

This project aimed to evaluate the role of ultrasound scan (USS) in children presenting with acute onset right iliac fossa (RIF) pain and suspected appendicitis.

METHODS

We retrospectively studied 100 consecutive children undergoing USS for RIF pain. Children with low to moderate clinical probability of appendicitis were seen by the surgical team and subsequently underwent USS by a radiologist or a sonographer with a special interest in paediatric USS. The clinical findings, blood tests, and radiological diagnosis led to a decision to operate, observe or discharge. USS findings were subsequently verified with the final histology. The six-month follow-up data of these patients were also analysed.

RESULTS

35 males, median age of 11 years (range 4-17), and 65 females, median age of 14 years (range 6-18) were included. A total of 23 appendicectomies were performed. On histology appendicitis was confirmed in 20, including 16 pre-operatively diagnosed on USS. 6 of these appendicectomies were performed on clinical suspicion with normal USS. 1 patient was diagnosed with neuroendocrine tumour of the appendix. Only 2 negative appendicectomies were performed. 62 patients were discharged without intervention. USS sensitivity was 74%, and specificity was 92% for appendicitis. An additional 16 patients were identified with alternate pathology including 5 ovarian cysts.

CONCLUSION

Appendicitis was more common in male patients; however, there was no difference in overall disease prevalence in male or female paediatric patients. Thus, USS is a valuable tool to exclude appendicitis in children with low to moderate probability.

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.