ainful for patients with peritonitis. A comparison of the effi-cacy of ultrasound v. CT scan is found in Table 30-2.MRI. MRI of the abdomen has a sensitivity of 0.95 (95% CI0.88–0.98) and specificity of 0.92 (95% CI 0.87–0.95) for iden-tification of acute appendicitis. 22 MRI is an expensive test thatrequires significant expertise to perform and interpret and isusually recommended in patients for whom the risk of ionizingradiation outweighs the relative ease of obtaining a contrastCT scan, i.e., pregnant or pediatric patients

ImagingImaging is often utilized to confirm a diagnosis of appendici-tis because a negative operation rate is acceptable in <10% ofmale patients and <20% of female patients. Routine use of cross-sectional imaging somewhat reduces the rate of negative laparot-omies. Imaging studies are most appropriate for patients in whoma diagnosis of appendicitis is unclear or who are at high risk fromoperative intervention and general anesthesia, such as pregnantpatients or patients with multiple comorbidities. Commonlyutilized imaging modalities include computerized tomography(CT), ultrasound (US), and magnetic resonance imaging (MRI).CT Scan. A contrast-enhanced CT scan has a sensitivity of0.96 (95% confidence interval [CI] 0.95–0.97) and specificity of0.96 (95% CI 0.93–0.97) in diagnosing acute appendicitis. 16,17Features on a CT scan that suggest appendicitis includeenlarged lumen and double wall thickness (greater than 6 mm)

Which of given imaging modalities is preferred for evaluating soft tissue abscesses in abdomen?Question 19Select one:a.CT scanb.PET scanc.Ultrasoundd.X-ray

Which imaging modality is preferred for diagnosing a herniated disc?Question 37Select one:a.Ultrasoundb.CT scanc.MRId.X-ray

wall thickening (greater than 2 mm), periappendiceal fatstranding, appendiceal wall thickening, and/or an appendicolith(Fig. 30-1). While there remains a concern of ionizing radia-tion exposure with a CT scan, typical low-dose CT scans resultin exposure of 2 to 4 mSv, which is not significantly higherthan background radiation (3.1 mSv).18 Recent trials have alsosuggested that although low-dose CT scans of 2 mSv do notgenerate high-resolution images, using these lower resolutionimages does not affect clinical outcomes. 19 Intravenous contrastis generally preferred in these studies, but it can be avoided inpatients with allergies or low estimated glomerular filtration rate(less than 30 mL/minute for 1.73 m 2 ). Several meta-analyseshave suggested that CT scan is more sensitive and specific thanultrasound in diagnosing appendicitis.Ultrasound. Ultrasonography has a sensitivity of 0.85 (95%CI 0.79–0.90) and a specificity of 0.90 (95% CI 0.83–0.95).20Graded compression ultrasonography is used to identify theanteroposterior diameter of the appendix. An easily compressibleappendix <5 mm in diameter generally rules out appendicitis.Features on an ultrasound that suggest appendicitis includea diameter of greater than 6 mm, pain with compression,presence of an appendicolith, increased echogenicity of the fat,and periappendiceal fluid. 21 Ultrasound is cheaper and morereadily available than CT scan, and it does not expose patients toionizing radiation, but it is user-dependent and has limited util-ity in obese patients. In addition, graded compression is usually

The most sensitive imaging method for detecting early osteomyelitis is:Question 56Select one:a.Bone Scanb.MRIc.X-Rayd.CT Scan