The Utility of Point Shear-wave Elastography to Assess for Hepatic & Pancreatic Fibrosis in Pediatric Cystic Fibrosis Patients

Liver disease is increasingly common in cystic fibrosis (CF). As new therapeutic options emerge, life expectancy increases and common hepatobiliary manifestations impact on quality of life and survival of CF patients. Hepatobiliary abnormalities in CF vary in nature and range from defects attributable to the underlying CFTR gene defect to those related to systemic disease and malnutrition. Today complications of liver disease represent the third most frequent cause of disease-related death in patients with CF.

Cystic fibrosis-associated liver disease (CFALD) belongs to the group of common symptoms of this disease; however, due to the lack of specific and sensitive CFALD diagnostic markers, the epidemiological data may be incomplete. According to various sources, the prevalence rate of CFALD, diagnosed on the basis of clinical, biochemical and imaging (ultrasonography) tests, is 2-37% in children and young adults.

Cirrhosis is a final, irreversible stage of liver damage that leads to the failure of the organ. While liver biopsy is considered the gold standard to assess for Hepatic Fibrosis; it is invasive and potentially life threatening. The prognosis and management of chronic liver disease depends on the extent and progression of liver fibrosis, which constitutes the most important predictor of disease outcome.

The gold standard for diagnosis and staging of liver fibrosis has been liver biopsy. In addition to being an invasive procedure with potential complications of bleeding and severe pain, sampling error is an intrinsic problem due to the small sample size in a heterogeneous process.7,8 Inter-observer variability also limits diagnostic consistency.9-11 The development of several blood markers such as platelets, hyaluronic acid, type IV collagen, aminotransferase/platelet ratio index (APRI) and algorithm based serum models (Fibro Index, FIB-4, and Fibro Test) have been used but are affected by factors unrelated to the liver.

In the last decade, methods to noninvasively quantify liver fibrosis have been developed. The first available method was transient elastography (TE).It is a single-element ultrasound transducer operating at 5 MHz built on the axis of a piston like vibrator. By pushing a button, low-frequency (50 Hz) transient vibrations are transmitted, and the generated elastic shear waves propagate through underlying tissues. Pulse-echo ultrasound acquisitions are used to follow the propagation of the shear wave and to measure its velocity .