Preface

Elastography is part of the daily practice of many medical specialists, including radiologists, gastroenterologists, rheumatologists, endocrinologists, gynecologists, urologists, nephrologists, and pediatricians. The role of elastography is emerging in adding quality information to the conventional ultrasound evaluation.

Ultrasound elastography comprises different techniques to measure tissue stiffness. There are either transversal or tangential forces that induce the deformation of the tissues, with deformation related to the degree of presented elasticity.

The value of elastography in chronic liver pathology is widely recognized. Shear wave techniques seem to be more appropriate for liver applications. They allow for the accurate screening, diagnosis, and follow-up of patients with alcohol-induced liver pathology. Metabolic-associated fatty liver disease is one of the most frequent chronic pathologies, affecting around one-quarter of the adult population. If the evaluation of steatosis is made by conventional ultrasound, quantification of steatosis, fibrosis, and inflammation, which are actually the predictors of the impact of the disease, is delivered by elastography. The ability of elastography, regardless of type, to rule out cirrhosis by assessing liver fibrosis has been described in chronic hepatitis C cases. The technique also brings valuable information regarding the severity and evolution of liver damage, even in children, in special situations of cystic fibrotic disease. In the case of progressive liver damage with the development of cirrhosis, regardless of background, elastography has a valuable predictive diagnostic capacity, identifying the presence and severity of portal hypertension, one of the most important complications of the disease.

The predictive value of elastography in the differential diagnosis of focal hepatic lesions is still to be evaluated since there is no consensus regarding the threshold values of the used elastographic parameters.

Extrapolation of the results obtained from chronic liver disease to chronic renal disease cannot be made. Future studies and the development of viscoelasticity evaluation should be done before recommending the use of elastography in renal pathology.

A particular aspect is the situation of pancreatic diseases, in which elastography is performed via an endoscopic approach. Both strain and shear wave is available for pancreatic pathology, with excellent discrimination of tumoral masses. Increased stiffness is associated with the vast majority of breast malignancies, elastography being currently used for risk upgrade or downgrade in breast nodular disease. and promising results in identifying the presence and the severity of the chronic disease.

The first application of elastography in cancer discrimination was for the breast. Increased stiffness is associated with the vast majority of breast malignancies, elastography being currently used for risk upgrade or downgrade in breast nodular disease. Moreover, the evolution of stiffness, measured by the shear wave technique, brings information about the response rate to cancer treatment. In thyroid nodular disease, elastography aids diagnostic prediction of thyroid cancer, as most thyroid cancers are stiff. The method is also important in the evaluation of diffuse thyroid pathology, with suggestive stiffness in autoimmune thyroid disease cases, both in adults and children. In hyperparathyroidism cases, elastography helps discriminate parathyroid versus thyroid tissue, showing promising results in identifying hyperplastic versus hypertrophic tissue.

Shear wave elastography demonstrates promising results in evaluating chronic muscle injuries, evaluating the degree of fibrosis, and the stage of healing after acute injuries. The same characteristics are described even in the pediatric population, monitoring the effectiveness of therapeutic interventions, altering the approach, or deciding the treatment duration.

I would like to thank my co-editor Professor Alina Popescu for the effort in gathering this team of experts with tremendous experience in the field of elastography. I would like to thank all the authors for their excellent work. All the authors are active both in the clinical field and in the academic milieu, and time is one of the most valuable assets that they have. I am grateful for the time they spent developing their excellent contributions. Finally, I would like to thank the team at IntechOpen for their constant support in developing this book.

> **Dana Stoian** Department of Internal Medicine, Discipline of Endocrinology, COE WFUMB, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania

#### **Alina Popescu**

Department of Internal Medicine II, Department of Gastroenterology and Hepatology, Center for Advanced Research in Gastroenterology and Hepatology, WFUMB Center of Education, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania

Section 1
