Ultrasound elastography. A possible improvement into the paraphernalia of pancreatic imaging.

Traditional imaging studies for evaluating pancreatic disease including abdominal ultrasound (US) and computerized tomography (CT) are widely utilized due to their availability, non-invasiveness, and familiarity on the part of physicians. Recently, the addition of endoscopic ultrasound (EUS), magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) has significantly contributed to the ability of evaluating the pancreatic ductal and parenchymal anatomy and staging the malignancy using tissue samples. At the same time, the role of endoscopic retrograde cholangiopancreatography (ERCP) has diminished with the use of these less invasive modalities. Limitations in these conventional techniques include a lack of sensitivity and specificity in diagnosing early chronic pancreatitis, difficulties in differentiating malignancy from chronic or focal pancreatitis, and accuracy of staging pancreatic malignancy, particularly with regard to vascular involvement. Several recent advances in traditional imaging techniques have been described, which may improve the capability of accurately diagnosing and staging pancreatic disease, i.e., multidetector CT, micro-bubble contrast-enhanced ultrasound, secretin-stimulated MRCP, optical coherence tomography, diffusion-weighted MRI and MR spectroscopy [1]. Very recently a novel method of pancreatic imaging has been introduced, namely the US/EUS elastography. Initial clinical applications have shown that US elastography might be able to distinguish tissues due to their specific consistency regarding differences of hardness and strain allowing diseased tissue to be distinguished from normal tissue. To tell the truth, elasticity imaging is nothing but an extension of the echopalpation of the earlier US methods for viewing tissue rigidity. Elasticity images consist of either an image of strain in response to force or an image of estimated elastic modulus. There are three main types of US elasticity imaging: elastography which tracks tissue movement during compression to obtain an estimate of strain, sonoelastography which uses color-Doppler to generate an image of tissue movement in response to external vibrations and tracking of shear wave propagation through tissue to obtain the elastic modulus [2]. Elasticity imaging is possible in almost all tissues. Breast mass elastography has potential for enhancing the specificity of US and mammography for cancer detection. Lesions in the thyroid, prostate gland and lymph nodes have been successfully imaged using elastography. Elasticity imaging may also be important in assessing the progress of ablation therapy, liver transplant rejection and cirrhosis. Vascular imaging including myocardium, blood vessel wall, plaque, lymphatic vessels and venous thrombi has also shown great potential. EUS elastography might also enhance the detection and differentiation of various solid tumors