Chronic pancreatitis and focal formations
Chronic pancreatitis gradually replaces glandular tissue with fibrous tissue, and this process occurs long before obvious signs of exocrine insufficiency appear. On conventional ultrasound, early changes are expressed only by a nonspecific increase in echogenicity, which is difficult to measure and compare over time. Elastography translates parenchymal compaction into numbers, allowing the progression of the disease to be monitored.
The second task is focal formations. Pseudocysts and areas of edema during exacerbation remain soft, but ductal adenocarcinoma is characterized by very high rigidity due to the dense stroma. This helps to identify the lesion requiring endoscopic puncture under ultrasound guidance.
The pancreas is located deep and covered by the stomach and intestinal loops, so the quality of the examination greatly depends on the preparation. You need to come strictly on an empty stomach, at least 6 hours without food, and in two days you should limit foods that cause gas formation.
What does elastography show?
Elastography measures the stiffness (elasticity) of tissue - a parameter that a doctor could previously assess only with his hands during palpation. Healthy tissue is soft and easily deformed, while scar, fibrous and tumor tissue is dense and rigid. The method translates this feeling into objective numbers that can be compared between studies.
The main practical value is in the differential diagnosis of focal formations. Benign nodes usually retain the elasticity of the surrounding tissue, while malignant ones are noticeably stiffer. This helps decide which nodes need to be monitored and which ones require a biopsy.
Compression and shear wave techniques
Compression elastography is based on light pressure with a sensor: the device compares tissue deformation and builds a color map. The method is qualitative - it shows what is harder and what is softer, but does not give absolute values.
Shear wave elastography (shear wave, which also includes liver fibroscan) uses the acoustic pulse of the device itself and measures the speed of propagation of the shear wave. The result is quantitative - in kilopascals, which allows you to track the dynamics during treatment.
Limitations of the method
The result is influenced by severe obesity, edema and active inflammation in the area of interest, as well as the depth of the formation: the deeper it is, the less reliable the measurements. Large calcifications and cysts produce artifacts.
Elastography is not an independent diagnosis, but one of the parameters. The final conclusion about the nature of the formation is given by a morphological study, that is, a biopsy.