Pancreatic ultrasonography (synonym: ultrasound of the pancreas) is a noninvasive diagnostic procedure used in radiology and internal medicine to detect pathologic (disease) processes of the pancreas. Sonographic evaluation of the pancreas can be performed using a variety of techniques. Both conventional abdominal sonography and endoscopic sonography allow, to varying degrees, assessment of the anatomic structures of the pancreas. Moreover, sonography of the pancreas can be further enhanced by color Doppler techniques (color Doppler).
Indications (areas of application)
- Chronic pancreatitis – the chronic form of pancreatitis is characterized by non-specific symptoms such as upper abdominal pain and malaise. Based on this, it is important to be able to rule out or determine the disease given the presenting symptoms. Pancreatic ultrasonography plays an important role in the detection of chronic pancreatitis. However, other procedures are necessary to exclude the disease.
- Pseudocysts – Pseudocysts are characterized by a boundary that, unlike true cysts, consists of scar tissue. As a result of tissue destruction, pseudocysts contain either serous or bloody fluid. Furthermore, it is possible that necrotic (dead) tissue debris is also involved in the formation of the pseudocyst. Conventional sonography represents the procedure of choice for imaging pseudocysts. However, in some circumstances, it may be necessary for additional diagnostic procedures such as computed tomography (CT) to be indicated. Pseudocysts frequently occur in the presence of chronic pancreatitis. Endosonography (endoscopic ultrasound (EUS); ultrasound examination performed from the inside, i.e., the ultrasound probe is brought into direct contact with the internal surface (for example, the mucosa of the stomach/intestine) by means of an endoscope (optical instrument)) is also a good way to visualize pseudocysts.
- Suspicion of space occupying lesions (tumor?).
- Calcifications – Calcifications in pancreatic tissue can also be detected very well with conventional sonography. Calcifications may also indicate chronic pancreatitis.
- Pancreatic ductal changes – the ductal system of the pancreas can be visualized with sonography, among other methods. Changes in the ducts occur primarily in chronic inflammatory processes and tumors.
The procedure
As mentioned above, there are various procedures for morphological assessment of the pancreas. However, special procedures are necessary to check the function of the pancreas, because no clear conclusions about the function of the organ can be drawn by morphological assessment. Functional tests can be divided into direct and indirect test procedures. Conventional pancreatic sonography
- Conventional pancreatic sonography allows excellent morphologic assessment of the pancreas, and the procedure can be considered a hazard-free and cost-effective method.
- In contrast to magnetic resonance imaging (MRI) and computed tomography (CT), this procedure has the advantage that the pancreas can be visualized in almost all possible sectional planes without exposing the patient to X-rays.
- However, it should be noted in pancreatic sonography that the sonographic image is qualitatively diminished by the location of the pancreas in the retroperitoneum. Nevertheless, the informative value of the procedure is to be judged as very good.
- Abdominal ultrasonography offers the possibility of diagnosing both ductal dilatations of the pancreas (dilatations of the ductal structures of the pancreas) and fluid accumulations and calcifications (calcifications of the pancreas). It should be noted, however, that the sensitivity (percentage of diseased patients in whom the disease is detected by the use of the procedure, i.e., a positive finding occurs) in diagnosing the disease at hand depends on the examiner on the one hand and on anatomical conditions on the other. Thus, a sensitivity of 48% to 90% can be achieved in the conventional sonographic assessment of the pancreas.
- Furthermore, it should be noted that the use of the procedure is associated with a relatively low resolution of the organ. Nevertheless, the majority of morphologically visible pathological processes can be detected with sonography.
Endoscopic sonography of the pancreas.
- Although this sonographic procedure represents a more complicated procedure compared with conventional sonography, endosonography of the pancreas (endoscopic ultrasound of the pancreas) allows very good simultaneous assessment of both ductal structures and the parenchyma of the pancreas (pancreatic tissue). Compared to other diagnostic methods for the assessment of the pancreas, such as endoscopic retrograde cholangiopancreatography (ERCP), endosonography of the pancreas has gained influence in recent years in the diagnosis of many diseases of the pancreas, since the sensitivity is very good, for example, in the presence of chronic pancreatitis (chronic inflammation of the pancreas), and the complication rate is lower compared to ERCP. Because of this, this method is already referred to by various specialists as a standard procedure for the diagnosis of chronic pancreatitis.
- Furthermore, it must be mentioned that endosonography can accurately image morphologic changes in the pancreatic head and corpus in particular because of its close proximity to the posterior wall of the stomach.
Color Doppler ultrasonography of the pancreas.
- Imaging of the pancreas using color Doppler ultrasonography allows the investigator to adequately visualize the flow characteristics of blood in the vasculature of the pancreas. In particular, space-occupying processes such as neoplasms (tumors) and inflammation-associated swelling can alter the flow properties, so the procedure is used especially to clarify inflammatory and tumorous space-occupying lesions as well as pseudocysts and cystic tumors.
- It should be noted, however, that no adequate evaluation of the diagnostic potential of color Doppler ultrasonography of the pancreas has been performed to date.
Assessment of the pancreas.
The lienal vein (dorsal (“towards the back”) of the pancreas) serves as a guide structure. Assessed are size of the pancreas, homogeneity and the presence of space. Pancreatitis (inflammation of the pancreas) is represented by swelling and fuzziness of the pancreas and changes in homogeneity. A sign of chronic pancreatitis is calcification. Dilatation (widening) of the pancreatic duct (pancreatic duct; normal value: < 0.2 cm) usually occurs in the presence of space-occupying lesions in the region of the pancreatic head or the papilla vateri (site where the ductus choledochus/main bile duct enters the duodenum/duodenum). If dilatation is present, a mass in the pancreatic head or papilla Vateri is suspected.
