Abstract
IntroductionShear wave elastography (SWE) has not been studied for diagnosing appendicitis. We postulated that an inflamed appendix would become stiffer than a normal appendix. We evaluated the elastic modulus values (EMV) by SWE in healthy volunteers, patients without appendicitis, and patients with appendicitis. We also evaluated diagnostic ability of SWE for differentiating an inflamed from a normal appendix in patients with suspected appendicitis.Materials and MethodsForty-one patients with clinically suspected acute appendicitis and 11 healthy volunteers were prospectively enrolled. Gray-scale ultrasonography (US), SWE and multi-slice computed tomography (CT) were performed. The EMV was measured in the anterior, medial, and posterior appendiceal wall using SWE, and the highest value (kPa) was recorded.ResultsPatients were classified into appendicitis (n = 30) and no appendicitis groups (n = 11). One case of a negative appendectomy was detected. The median EMV was significantly higher in the appendicitis group (25.0 kPa) compared to that in the no appendicitis group (10.4 kPa) or in the healthy controls (8.3 kPa) (p<0.001). Among SWE and other US and CT features, CT was superior to any conventional gray-scale US feature or SWE. Either the CT diameter criterion or combined three CT features predicted true positive in 30 and true negative in 11 cases and yielded 100% sensitivity and 100% specificity. An EMV of 12.5 kPa for the stiffest region of the appendix predicted true positive in 28, true negative in 11, and false negative in two cases. The EMV (≥12.5 kPa) yielded 93% sensitivity and 100% specificity.ConclusionOur results suggest that EMV by SWE helps distinguish an inflamed from a normal appendix. Given that SWE has high specificity, quantitative measurement of the elasticity of the appendix may provide complementary information, in addition to morphologic features on gray-scale US, in the diagnosis of appendicitis.
Highlights
Shear wave elastography (SWE) has not been studied for diagnosing appendicitis
Patients were classified into appendicitis (n = 30) and no appendicitis groups (n = 11)
The median elastic modulus values (EMV) was significantly higher in the appendicitis group (25.0 kPa) compared to that in the no appendicitis group (10.4 kPa) or in the healthy controls (8.3 kPa) (p,0.001)
Summary
Shear wave elastography (SWE) has not been studied for diagnosing appendicitis. We postulated that an inflamed appendix would become stiffer than a normal appendix. We evaluated diagnostic ability of SWE for differentiating an inflamed from a normal appendix in patients with suspected appendicitis. Acute appendicitis is a common abdominal emergency requiring surgery Diagnostic imaging modalities such as abdominal ultrasonography (US) and computed tomography (CT) have led to a decrease in the perforation rate [1,2]. The disadvantages of CT are radiation exposure and contrast-induced hypersensitivity reactions The choice of these studies depends upon patient factors such as age, obesity or pregnancy, and institutional factors such as the availability of US and CT examinations [3,4]. Magnetic resonance imaging (MRI) is emerging as a promising modality, as MRI is operator-independent and avoids radiation exposure and the use of contrast agent. Leeuwenburgh et al [8] found that the diagnostic accuracies of conditional MRI following US or immediate MRI were comparable to those of conditional CT following US in adult patients with suspected appendicitis
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