Endoscopic ultrasound elastography

Abstract

Endoscopic ultrasound (EUS) is a reference technique for diagnosing and staging several different diseases. EUS-guided biopsies and fine needle aspirations are used to improve diagnostic performance of cases where a definitive diagnosis cannot be obtained through conventional EUS. However, EUS-guided tissue sampling requires experience and is associated with a low but not negligible risk of complications. EUS elastography is a non-invasive method that can be used in combination with conventional EUS and has the potential for improving the diagnostic accuracy and reducing the need for EUS-guided tissue sampling in several situations. Elastography measures tissue stiffness by evaluating changes in the EUS image before and after the application of slight pressure to the target tissue by the ultrasonography probe. Pathologic processes such as cancerization and fibrosis alter tissue elasticity and therefore induce changes in elastographic appearance. Qualitative elastography depicts tissue stiffness using different colors, whereas quantitative elastography renders numerical results expressed as a strain ratio or hue histogram mean. EUS elastography has been proven to differentiate between benign and malignant solid pancreatic masses, as well as between benign and malignant lymph nodes with a high accuracy. Studies have also demonstrated that the early changes of chronic pancreatitis can be distinguished from normal pancreatic tissues under EUS elastography. In this article, we review the technical aspects and current clinical applications of qualitative and quantitative EUS elastography and emphasize the potential additional indications that need to be evaluated in future clinical studies.

Endoscopic ultrasound: Elastographic lymph node evaluation

“…[ 42 ] Another possible way to quantify strain is by mean of hue histograms. [ 6 43 ] Elastography has already proved its valuable clinical utility in applications such as breast cancer diagnosis[ 44 45 46 47 48 49 ] or assessment of liver fibrosis,[ 43 50 51 52 53 54 55 56 57 58 ] adding complementary information to conventional US. It has also shown promising results in applications such as thyroid nodules,[ 59 60 ] pancreatic masses,[ 19 21 28 61 62 ] chronic pancreatitis,[ 42 63 64 ] autoimmune pancreatitis,[ 65 ] prostate cancer,[ 66 67 68 ] or LNs assessment.…”

“…[ 1 2 3 4 ] One of the best diagnostic tools to assess the digestive tract and surrounding organs is endoscopic ultrasound (EUS), but one of its major limitations is the limited capacity to determine the exact nature of a lesion. [ 5 6 7 ] Differential diagnosis between benign and malignant lymph nodes (LNs) based on the EUS appearance is difficult and frequently requires EUS-guided fine needle aspiration biopsy (EUS-FNAB) for confirmation of malignancy. [ 8 9 10 11 12 ] Recently, the European Society of Gastrointestinal Endoscopy (ESGE) published recommendations on EUS-guided sampling made for various settings, including LNs.…”

“…[ 21 ] Also, it requires experience and it is associated with a risk of complications which, even if it is low, is not negligible. [ 6 22 ] According to the guidelines of the ESGE published by Dumonceau et al , contrast-enhanced EUS and EUS-elastography are new techniques developed to increase the negative predictive value (NPV) of EUS-FNAB. [ 13 ] Recent researches and detailed technical explanations published indicate that these techniques may potentially be useful to select diagnostically significant LNs and also the most suspicious area of a LN to be targeted for FNAB.…”

Accuracy of endoscopic ultrasound-guided tissue acquisition in the evaluation of lymph nodes enlargement in the absence of on-site pathologist

“…This result could have been related to the procurement of a non-diagnostic part of the lymph node, e.g ., the necrotic portion. Evidence suggests that employing complementary tools, such as contrast-enhanced EUS or EUS elastography, might help in guiding to the area for tissue procurement, thus improving the diagnostic yield[ 24 , 25 ]. However, further studies are required to validate the benefits of these advanced imaging techniques associated with EUS.…”

“…According to recent reports, techniques such as EUS elastography, which helps distinguish between benign and malignant lesions, have gained much attention over the last decade[ 31 , 32 ]. Malignant lesions tend to be solid due to pathologic processes that decrease tissue elasticity and hence increase tissue stiffness, resulting in a blue pattern on qualitative EUS elastography[ 25 ]. Targeting the needle to the “solid area” during the tissue acquisition process could potentially improve the diagnostic yield of malignant lesions.…”