Comparison of Diagnostic Accuracy of CT scan and USG in Right Upper Quadrant Pain: A Review Analysis

Purpose: Acute right upper quadrant (RUQ) pain is a common presenting symptom in emergency departments and outpatient medical practices, and is most commonly attributable to biliary and hepatic pathology. The main objective of the study is to systematically analyse the comparison of diagnostic accuracy of ultrasound and computed tomography in right upper quadrant pain. Material and methods: This study was conducted using a systematic search on Google scholar, Pubmed and Web of science published until 20 th June 2020. The cited references of retrieved articles and previous reviews were also manually checked to identify any additional eligible studies with indexed search terms for cholecystitis, US, cholescintigraphy, CT, and MR imaging. Results: After excluding duplicates and articles that did not meet the inclusion criteria, we obtained 30 articles with full-texts which were read for further evaluation, where another 60 were excluded as irrelevant. Overall, we included 30 articles that directly match on the inclusion criteria. Conclusion: It is concluded that RUQ pain were not as good as sensitivities reported in prior studies. CT was statistically significantly better for the diagnosis of RUQ pain than US, most likely because of an unclear clinical picture, the patient population, and a high proportion of poor-quality US examinations. However, US is still our first test of choice if RUQ pain is suspected clinically, whereas CT is performed when the clinical picture is unclear. for RUQ,


INTRODUCTION
Acute right upper quadrant (RUQ) pain is a common presenting symptom in emergency departments and outpatient medical practices, and is most commonly attributable to biliary and hepatic pathology. Ultrasound should be used as a first-line imaging modality for the diagnosis of gallstones and cholecystitis, as it allows the differentiation of medical and surgical causes of upper abdominal pathology, and in many circumstances is sufficient to guide patient management. Knowledge of strengths and limitations of ultrasound in the evaluation of RUQ is paramount in correct diagnosis 1 . Approximately 10%-15% of adults in the Western population have gallstones. Each year, between 1% and 4% of these individuals become symptomatic. With a prevalence of 5%, acute cholecystitis is a common entity in patients presenting at the emergency department with acute abdominal pain 2 . The condition can be life threatening and may require direct medical intervention. The preferred treatment is a laparoscopic cholecystectomy. Timing of the operation has long been debated, but through a Cochrane Library review, the conclusion was reached that early laparoscopic cholecystectomy is safe. Accurate and timely diagnosis is essential to initiate adequate treatment 3 . Clinical history, physical examination, and routine laboratory tests alone result in too many unnecessary cholecystectomies and missed diagnoses. Therefore, imaging plays a major role in the management strategy and is performed in a large number of patients to improve diagnostic accuracy 4 . Ultrasonography (US) is the primary imaging modality of choice for initial assessment of acute right upper quadrant abdominal (RUQ) pain, particularly in the emergency department (ED) setting. The American College of Radiology (ACR) Appropriateness Criteria for US have a rating of 9 (out of 9) in patients with appropriate clinical indications 5 . There are a variety of differential considerations for RUQ pain, and US is a fast cost-effective real-time dynamic modality, which does not use ionizing radiation or nephrotoxic intravenous contrast medium and provides a definitive diagnosis or at least a considerably narrowed list of differential possibilities. Multiple organ systems are included at standard RUQ US, and a variety of disease processes that are diagnosable at US can be identified, including hepatic, pancreatic, adrenal, renal, gastrointestinal, vascular, and thoracic conditions, all of which may manifest with RUQ pain 6 . Therefore, familiarity with the spectrum of disease processes outside of the gallbladder and biliary tree that may manifest with RUQ pain and US recognition of these alternative causes is pivotal for early accurate diagnosis and efficient appropriate management. Early accurate diagnosis is particularly critical for those conditions that require timely intervention such as pyonephrosis and appendicitis, among others. In some cases, subsequent computed tomography (CT), magnetic resonance (MR) imaging including MR cholangiopancreatography (MRCP), or cholescintigraphy may be considered as the next appropriate management, depending on the clinical situation and US findings 7 . For this purpose we performed a systematic review of comparison studies of diagnostic accuracy of ultrasound and computed tomography in right upper quadrant pain.

METHODOLOGY OF THE STUDY Search strategy
This retrospective study was conducted using a systematic search on Google scholar, Pubmed and Web of science published until 20 th June 2020.
Inclusion criteria  All those study papers which include the diagnostic accuracy of ultrasound and computed tomography in right upper quadrant pain.

Exclusion criteria
 Studies were excluded if they were case reports or if the study population consisted of patients in an intensive care unit.

Study selection
The cited references of retrieved articles and previous reviews were also manually checked to identify any additional eligible studies with indexed search terms for cholecystitis, US, cholescintigraphy, CT, and MR imaging. Imaging study reports were reviewed for gallbladder and non-gallbladder explanations of right upper quadrant pain and were considered positive for cholecystitis when two or more supportive features were present. Encounter outcomes were evaluated on the basis of pathology data and clinical management. An article was considered potentially eligible if US, cholescintigraphy, CT, or MR imaging was evaluated in adult patients who were suspected of having acute cholecystitis. Full-text versions of potentially eligible articles were obtained for further evaluation. The reference lists of the included studies were manually searched to identify other potentially eligible articles. Disagreements in study selection between the two reviewers were resolved through discussion.

Data extraction and analysis
The data was collected and analysed systematically. All citations were imported into a bibliographic database and duplicates were removed. Title, abstract and then full-text of all articles were screened for eligibility.

RESULTS
All those studies who met the inclusion criteria were and published during 2010 to 2020 were added in this review analysis. There were total 310 studies that identified initially from PubMed, Google scholar and Web of Science databases. After excluding duplicates and articles that did not meet the inclusion criteria, we obtained 30 articles with full-texts which were read for further evaluation, where another 60 were excluded as irrelevant. Overall, we included 30 articles that directly match on the inclusion criteria. Vincent et al 2020 CT imaging in the pediatric population has provided a higher sensitivity and diagnostic accuracy. However, the diagnostic benefit of US cannot be excluded in this patient population. 10 Khan et al 2020 Integrating US in primary health care empowers primary health-care physicians to provide high-quality, safe, and cost-effective care to the patients.
Computed tomography (CT) has not been widely studied for the evaluation of right upper quadrant pain. It may be considered in patients with inconclusive ultrasonography or cholescintigraphy results or to help guide surgical planning. Several small studies of magnetic resonance imaging (MRI) suggest that it may be useful for evaluating acute cholecystitis, with a sensitivity (85%) and specificity (81%) similar to that of ultrasonography. 14 MRI can be used in patients with equivocal ultrasonography findings or to visualize hepatic and biliary abnormalities that cannot be characterized on ultrasonography.