The utility of acoustic radiation force impulse imaging in diagnosing acute appendicitis and staging its severity

Current Developments and Role of Intestinal Ultrasound including the Advent of AI

Intestinal ultrasound is a non-invasive, safe, and cost-effective technique to study the small and large intestines. In addition to conventional B-mode and color doppler imaging, new US tools have been developed in more recent years that provide auxiliary data on many GI conditions, improving the diagnosis and assessment of relevant outcomes. We have reviewed the more recent literature (from 2010 onwards) on auxiliary tools in bowel ultrasound such as elastography techniques, CEUS, SICUS, and the potential contribution by artificial intelligence (AI) to overcome current intestinal ultrasound limitations. For this scoping review, we performed an extensive literature search on PubMed and EMBASE to identify studies published until December 2023 and investigating the application of elastography techniques, CEUS, SICUS, and AI in the ultrasonographic assessment of the small and large intestines. Multiparametric intestinal ultrasound shows promising capabilities in Crohn's disease, while less is known about the role in ulcerative colitis. Despite some evidence, the CEUS role as a point-of-care examination tool for rare conditions such as intestinal GvHD and ischemic small bowel disease seems promising, possibly avoiding the need to perform further cross-sectional imaging. The use of AI in intestinal ultrasound is still anecdotical and limited to acute appendicitis.

The Role of Transabdominal Ultrasound Elastography in Gastrointestinal Non-Liver Diseases: Current Application and Future Prospectives

Ultrasound imaging is the first-line investigation for patients with abdominal symptoms, as it effectively depicts the gastrointestinal tract and enables the diagnosis of multiple pathological conditions. Among different recent ultrasound technological advancements, elastography enables the evaluation of various tissue characteristics, such as neoplastic transformation or fibroinflammatory status. In recent years, ultrasound elastography has been utilized extensively for the study of liver diseases and in numerous other clinical settings, including gastrointestinal diseases. Current guidelines suggest the use of transabdominal ultrasound elastography to characterize bowel wall lesions, to assess gastrointestinal contractility, to diagnose and grade chronic pancreatitis; however, no specific indications are provided. In the present paper, we summarize the evidence concerning the application of different ultrasound elastography modalities in gastrointestinal non-liver diseases.

Two-dimensional shear wave elastography can improve the diagnostic accuracy of ultrasonography in acute appendicitis

AIM

We aimed to evaluate the effectiveness of combining 2-dimensional shear wave elastography (2D-SWE) with ultrasonography (US) in diagnosing acute appendicitis in patients with suspected acute appendicitis.

METHODS

Clinical and laboratory findings, gray-scale US and 2D-SWE imaging features, operation information, and pathology results of 48 patients diagnosed with acute appendicitis who presented with right lower quadrant pain were prospectively evaluated. We compared the findings to the US and SWE imaging features of 79 asymptomatic patients.

RESULTS

Mean Alvarado score and appendix diameter were statistically significantly higher for acute appendicitis (p < 0.001). In patients with acute appendicitis, mesenteric lymphadenopathy and fat stranding were also more frequent (p < 0.001). The mean velocity and kPa values for appendix and mesenteric fat were statistically significantly higher in acute appendicitis (p < 0.001).

CONCLUSION

In the diagnosis of acute appendicitis, 2D-SWE increases the diagnostic performance of gray-scale US in the differentiation of inflamed and normal appendixes.

Utility of 2-Dimensional Shear Wave Elastography for Assessment of the Bladder Wall in Children With Acute Cystitis

OBJECTIVES

The aim of this study was to investigate the efficacy of 2-dimensional (2D) shear wave elastography (SWE) in the diagnosis of acute cystitis (AC) in children.

METHODS

Between June 2019 and March 2020, 126 children with AC and 126 healthy participants were prospectively investigated by 2D SWE and B-mode ultrasound. Elastographic measurements were performed by drawing the contours of the posterior wall of the bladder between the ureter orifices using a free region of interest. The quantitative 2D SWE values of the patients and the healthy group were compared.

RESULTS

The mean 2D SWE values of the bladder wall were significantly higher in patients with AC compared to the healthy group (P = .001). On B-mode ultrasound imaging, the bladder wall thickness of patients with AC was higher than that in the healthy group (P = .001). On 2D SWE, when the cutoff value used was 9.25 kPa, the sensitivity, specificity, positive predictive value, and negative predictive value were 92.1%, 88.1%, 89.3%, and 92.6%, respectively, whereas when the cutoff value used was 1.72 m/s, the sensitivity, specificity, positive predictive value, and negative predictive value were 90.5%, 88.9%, 89.1%, and 90.7%. There was a statistically significant positive correlation between the 2D SWE values and wall thickness measurements (P < .001).

CONCLUSIONS

Two-dimensional SWE is a noninvasive, fast, and effective imaging method to evaluate the bladder wall in children with AC.

Evaluation of the Clinical Effectiveness of Shear Wave Elastography in Pediatric Cases With Acute Appendicitis

ABSTRACT

To determine sensitivity and specificity of shear wave elastography in pediatric patients diagnosed with acute inflammation of the appendix. Forty-eight patients who were referred for abdominal pain, with 18 volunteers recruited for the evaluation. Alvarado scores were calculated on the patients. The elasticity and stiffness of the inflamed appendix tissues of patients and controls were measured using shear wave elastography. The anterior, posterior, and medial parts of the appendix tissue were measured, calculating the highest elasticity values in kPa. In the end, 32 patients with Alvarado scores between 7 and 9 (group 1) underwent surgery, whereas 3 of them had pathological specimens reporting as normal. Eight of the patients whose Alvarado scores were between 4 and 6 and had inflammatory conditions of the appendix (group 2), plus the control group totaled 16 patients (group 3). The median shear wave value was found to be significantly higher in group 1 (14.7 kPa) than in either group 2 (12.7 kPa) or group 3 (9.3 kPa) (P < 0.01). In the evaluation of the receiver operating characteristic curve, the cutoff value was discovered to be 14.3 kPA (95% CI: 0.753-0.995) in the acute appendicitis group, with a 100% sensitivity and 79.17% specificity. Shear wave elastography examination is not considered an invasive method and is an easily accessible diagnostic tool that can be used to differentiate between inflamed and noninflamed tissue in children. The quantitative measurement for flexibility of the appendix contributes to the diagnosis.

Reliability of standardized reporting system of acute appendicitis in adults at low-dose 320-rows CT

Aim

To assess the reliability of a standardized reporting system of acute appendicitis at low-dose 320-rows CT.

Subjects and Methods

Retrospective analysis CT of 78 patients with pathologically proven acute appendicitis. The study was performed at a low-dose 320-rows CT. The image analysis was performed by 2 radiologists according to a standardized reporting system of acute appendicitis.

Results

There was an excellent overall of the inter-observer agreement of both observers for the standardized reporting system of acute appendicitis (K = 0.89, 95 % CI = 0.87-0.92, P = 0.001). There was good inter-observer agreement for visualization of the appendix (K = 0.78, P = 0.001), the tip diameter (K = 0.75, P = 0.001), and a single wall thickness of appendix (K = 0.77, P = 0.001). There was excellent inter-observer agreement for outer to outer wall diameter (K = 0.82, P = 0.001), mucosal hyper-enhancement (K = 0.80, P = 0.001), appendicolith (K = 0.86, P = 0.001), gas in the appendix (K = 0.82, P = 0.001), surrounding fat stranding (K = 0.81, P = 0.001), focal cecal thickening (K = 0.85, P = 0.001), peri-appendiceal air (K = 0.87, P = 0.001), peri-appendicular fluid collection, phlegmon, or abscess (K = 0.82, P = 0.001), and right ovary cyst (K = 0.83, P = 0.001).

Conclusion

we concluded that excellent reliability of a standardized reporting system of acute appendicitis in the adults using low-dose 320-rows CT.

Efficacy of Strain Elastography in Diagnosis and Staging of Acute Appendicitis in Pediatric Patients

Background

In the present study, the role and efficiency of strain elastography (SE) were evaluated in diagnosis and staging of acute appendicitis in pediatric patients.

Material/Methods

We enrolled 225 pediatric patients with suspected clinical and laboratory findings of acute appendicitis. Gray-scale sonographic findings were recorded and staging was made by the colorization method of SE imaging. Appendectomy was performed in all patients and the results of the surgical pathology were compared with the imaging findings. The sensitivity, specificity, and accuracy of SE imaging were determined in terms of evaluating the “acute appendicitis”.

Results

Sonographic evaluation revealed acute appendicitis in 100 patients. Regarding the SE analysis, cases with appendicitis were classified into 3 groups as: mild (n=17), moderate (n=39), and severe (n=44). The pathological evaluation revealed 95 different stages of appendicitis and normal appendix in 5 cases: acute focal (n=10), acute suppurative (n=46), phlegmonous (n=27), and perforated (n=12), regarding the results of surgical pathology. Five patients with pathologically proven “normal” appendix were noted as “mild stage appendicitis” based on gray scale and SE analysis. In total, when gray-scale and SE results were compared with pathology results regardless of the stage of appendicitis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rates were 96%, 96%, 95%, 96.8%, and 96%, respectively. No statistically significant difference was detected between other groups (P<0.05).

Conclusions

In acute appendicitis, the use of SE imaging as a supportive method for the clinical approach can be useful in diagnosis, and its results are closely correlated with the histopathologic stage of appendix inflammation.

Elastography for the pancreas: Current status and future perspective

Elastography for the pancreas can be performed by either ultrasound or endoscopic ultrasound (EUS). There are two types of pancreatic elastographies based on different principles, which are strain elastography and shear wave elastography. The stiffness of tissue is estimated by measuring the grade of strain generated by external pressure in the former, whereas it is estimated by measuring propagation speed of shear wave, the transverse wave, generated by acoustic radiation impulse (ARFI) in the latter. Strain elastography is difficult to perform when the probe, the pancreas and the aorta are not located in line. Accordingly, a fine elastogram can be easily obtained in the pancreatic body but not in the pancreatic head and tail. In contrast, shear wave elastography can be easily performed in the entire pancreas because ARFI can be emitted to wherever desired. However, shear wave elastography cannot be performed by EUS to date. Recently, clinical guidelines for elastography specialized in the pancreas were published from Japanese Society of Medical Ultrasonics. The guidelines show us technical knacks of performing elastography for the pancreas.

Assessment of Placental Stiffness Using Acoustic Radiation Force Impulse Elastography in Pregnant Women with Fetal Anomalies

Objective

We aimed to evaluate placental stiffness measured by acoustic radiation force impulse (ARFI) elastography in pregnant women in the second trimester with a normal fetus versus those with structural anomalies and non-structural findings.

Materials and Methods

Forty pregnant women carrying a fetus with structural anomalies diagnosed sonographically at 18–28 weeks of gestation comprised the study group. The control group consisted of 34 healthy pregnant women with a sonographically normal fetus at a similar gestational age. Placental shear wave velocity (SWV) was measured by ARFI elastography and compared between the two groups. Structural anomalies and non-structural findings were scored based on sonographic markers. Placental stiffness measurements were compared among fetus anomaly categories. Doppler parameters of umbilical and uterine arteries were compared with placental SWV measurements.

Results

All placental SWV measurements, including minimum SWV, maximum SWV, and mean SWV were significantly higher in the study group than the control group ([0.86 ± 0.2, 0.74 ± 0.1; p < 0.001], [1.89 ± 0.7, 1.59 ± 0.5; p = 0.04], and [1.26 ± 0.4, 1.09 ± 0.2; p = 0.01]), respectively.

Conclusion

Placental stiffness evaluated by ARFI elastography during the second trimester in pregnant women with fetuses with congenital structural anomalies is higher than that of pregnant women with normal fetuses.

How to diagnose acute appendicitis: ultrasound first

Acute appendicitis (AA) is a common abdominal emergency with a lifetime prevalence of about 7 %. As the clinical diagnosis of AA remains a challenge to emergency physicians and surgeons, imaging modalities have gained major importance in the diagnostic work-up of patients with suspected AA in order to keep both the negative appendectomy rate and the perforation rate low. Introduced in 1986, graded-compression ultrasound (US) has well-established direct and indirect signs for diagnosing AA. In our opinion, US should be the first-line imaging modality, as graded-compression US has excellent specificity both in the paediatric and adult patient populations. As US sensitivity is limited, and non-diagnostic US examinations with non-visualization of the appendix are more a rule than an exception, diagnostic strategies and algorithms after non-diagnostic US should focus on clinical reassessment and complementary imaging with MRI/CT if indicated. Accordingly, both ionizing radiation to our patients and cost of pre-therapeutic diagnosis of AA will be low, with low negative appendectomy and perforation rates.

Main Messages

• Ultrasound (US) should be the first imaging modality for diagnosing acute appendicitis (AA).

• Primary US for AA diagnosis will decrease ionizing radiation and cost.

• Sensitivity of US to diagnose AA is lower than of CT/MRI.

• Non-visualization of the appendix should lead to clinical reassessment.

• Complementary MRI or CT may be performed if diagnosis remains unclear.