Ultrasound signs of pancreatic cancer

Complex ultrasound of pancreatic cancer

Based on the data from ultrasound, an algorithm was developed for examining patients suffering from pancreatic cancer:

• a real-time, real-time, percutaneous B-mode examination widely used to detect pancreatic tumors is essentially a screening method from which a patient is examined;
• color Doppler scanning or B-mode examination in combination with the use of carbon dioxide (microbubbles CO ₂ ) as a contrast agent, provides additional opportunities in the differential diagnosis of the tumor process and inflammatory changes in the pancreas;
• color Doppler scanning using DCS or EDC modes provides information on the nature of the relationship between the tumor and the vessels of the portal vein system, the inferior vena cava system, as well as the aorta and its branches.

If the diagnosis is not finally established, then on the basis of the results of a comprehensive ultrasound, a decision is made to choose the necessary additional research method or their combined use. These include: US-endoscopic examination, ultrasound examination, percutaneous aspiration biopsy of the pancreas under the supervision of ultrasound. Intraoperative ultrasound allows to specify the type and volume of the operation.

Diagnosis of pancreatic cancer in B-mode in real time is based on direct and indirect signs. Direct signs include the identification of a solitary focus or cavity of a non-uniform density with the presence of a line of demarcation between the tumor and the pancreatic parenchyma. Tumor rearrangement of the pancreatic parenchyma is the main direct sign of the presence of the tumor. The restructuring of the structure in the affected area causes a change in the intensity of the reflection of the echoes from the tumor. The following variants of tumor echogenicity are distinguished: hypoechoic, hyperechoic, isoechoic and mixed.

According to our data, ultrasound in the B-mode of 131 patients with pancreatic adenocarcinoma, the localization of the process in the head was noted in 62% of observations, in the body - in 12%, tail - 24% and total defeat - in 2% of cases. In most cases, gipoehogenic formations were diagnosed - 81.7%, mixed echogenicity - in 10.7% of cases, hyperechoic - in 4.5%, and isoechoic - in 3.1% of cases.

The possibility of ultrasound in the B-mode in the diagnosis of tumors depends on the location and size. Depending on the size of the tumor, the size of the gland can remain unchanged or local or diffuse increase is noted.

Indirect signs of adenocarcinoma include enlargement of the pancreatic duct, expansion of the common bile duct (OZHP). Obstruction of the main pancreatic duct (GPP), caused by compression or germination of the tumor, can occur directly in the area of its passage into the ampoule, followed by dilatation distal to the level of obstruction. In this case, the flow in the body and / or the head with a diameter of more than 3 mm is visualized. We noted a dilatation of the main pancreatic duct from 4 to 11 mm in 71% of cases when the tumor was located in the head of the pancreas. When the tumor is located in the head of the pancreas and is close to the intrapancreatic part of the common bile duct, due to tumor invasion, circular compression of the tumor or tumor growth in the lumen of the duct, obstruction of the common bile duct develops. With a diameter of the total bile duct of 12-17 mm, the lumen of the intrahepatic bile ducts reached 8 mm in combination with an increase in the size of the gallbladder. Expansion of the intrahepatic bile ducts may be due to the presence of a tumor in the head of the pancreas or lymph nodes in the hepato-duodenal ligament.

With the localization of cancer in the region of the hook-shaped process, it is not always possible to adequately visualize and evaluate changes in the early stage of the disease according to ultrasound in the B-mode. As the process spreads and the pancreatic head infiltrates, the tumor masses reach the level of the terminal section of the common bile duct. However, these changes, as a rule, are diagnosed already at a late stage of the disease. Therefore, a tumor originating from a hook-shaped process is characterized by dilatation of the common bile duct, GLP and development of jaundice in the late stage of the disease.

Differentiate the echographic picture of cancer is necessary primarily with local forms of pancreatitis, cancer of the large duodenal papilla, sometimes pseudocysts, lymphomas, metastases in the pancreas. Tactically important is the recording of clinical and laboratory data in conjunction with the results of a biopsy.

Additional possibilities in the differential diagnosis of the tumor process and inflammatory changes in the pancreas open up the use of color Doppler scanning in the regime of CDC, EDC and / or B-mode in combination with the use of carbon dioxide. We analyzed additional possibilities of obtaining the necessary information using color Doppler scanning. When using this technique, the presence of blood vessels, the nature and speed of blood flow in them were determined. When duplex scanning in patients with pancreatic cancer, either there is no blood flow of the vessels inside the tumor, or vessels with predominantly arterial blood flow of collateral type, with a diameter of 1-3 mm, LCS-10-30 cm / s are recorded. In none of the observations were the vessels enveloping the tumor in the form of a rim were detected.

Echocontrast agents are used to amplify the ultrasonic signal reflected from red blood cells. In our work, the levovist was used. Studies were conducted in two stages in three patients with pancreatic cancer and six with chronic pancreatitis. At the first stage ultrasound examination of the vascular bed in the head of the pancreas was performed. On the second one, the blood flow in the vessels of the pancreas head was evaluated after intravenous administration of 6 ml levovist at a concentration of 400 mg / ml, followed by comparing the signal intensity from the blood flow before and after the application of the levovist. In pancreatic cancer, in the first stage of the study, three patients had no blood flow inside the tumor. After the introduction of a levovist after 15-20 seconds for one or two minutes, arterial vessels with a diameter of up to 2 mm with a collateral type of blood flow were clearly visualized in two cases. Among six patients with CP at the first stage in four cases in the head of the pancreas, arteries with the main type of blood flow and veins were visualized. At the second stage, the recording of the course of the previously recorded vessels markedly improved. In the remaining observations, an image of the vessels appeared, mainly veins, which had not previously been determined. Thus, based on the accumulated experience, we recommend the use in complex diagnostic situations of color Doppler scanning in the regimes of the DCC _: EHD for differential diagnosis of pancreatic diseases.

The simplest substance that enhances the B-mode image is carbon dioxide (micro bubbles of CO ₂ ). The introduction into the celiac trunk of the microballoons CO ₂ during the hagiographic study in the study of the pancreas using ultrasound in B-mode is essentially a combined diagnostic method. The use of carbon dioxide makes it possible to more clearly confirm and differentiate the nature of the process in the pancreas. According to Kazumitsu Koito et al. During the examination of 30 patients with pancreatic cancer and 20 - chronic pancreatitis, depending on the filling zone lesions microbubbles C0 ₂, to diagnose the presence and extent of vascularization. The authors found that the cancerous tumor in 91% of the observations is hypovascular, the zone of HP in 95% of cases is isovascular. Comparison of the results of ultrasound in the B-mode using carbon dioxide, computed tomography and digital subtraction angiography in differential diagnosis of pancreatic cancer and CP showed that the sensitivity of the methods is 98%, 73% and 67%, respectively.

One of the key points in determining the resectiveness of cancer is the assessment of the state of the main vessels and the degree of their involvement in the tumor process. Already at the pre-operative stage, according to the US-study data, you can obtain the necessary information. With the localization of cancer in the head of the pancreas, as a rule, a focused study of the superior mesenteric vein, portal vein and its confluence, the superior mesenteric artery, the common hepatic artery and the celiac trunk, in the body - the celiac trunk, the common hepatic and splenic arteries, in the tail - celiac trunk and splenic vessels. In determining the resectability of a tumor, the condition of the inferior vena cava also matters. In our opinion, to evaluate the state of vessels according to color Doppler scan it is expedient to analyze:

1. Localization and anatomical location of the main arteries and veins relative to the tumor (the vessel does not contact the tumor, contacts the tumor, is located in the tumor structure).
2. The condition of the wall and lumen of the vessel (echogenicity of the vessel wall is not changed, increased, the size of the lumen is not changed, changed at the site of contact with the tumor).
3. The values of the linear velocity of blood flow throughout the vessel, accessible by ultrasound imaging.

When the vessel is in contact with the tumor, recording a local increase in LCS indicates a hemodynamically significant extravasal compression of the vessel with the tumor. In this situation, information on tumor invasion into the vessel wall is of primary importance for determining the tumor resectability. An increase in the echogenicity of the vessel wall at the site of contact with the tumor testifies either to the fixation of the tumor or to the tumor germination of the vessel wall. An increase in the echogenicity of the wall and the presence of a substrate in the lumen of the vessel indicate the growth of the vessel by a tumor. The absence of an ultrasound image of the vessel, the anatomical course of which is located in the tumor structure, also indicates the germination of the vessel. In addition, with pancreatic cancer, a parietal or occlusive thrombus often develops in the superior mesenteric vein and / or splenic vein. A thrombosis of these veins can spread to the portal vein.

To date, a three-dimensional reconstruction of the tumor of the pancreas and nearby major vessels using a combination of B-mode and angiography makes it possible to assess their anatomical relationship and degree of contact. However, in order to solve the problem of the state of the vessel wall at the site of contact with the tumor, the data obtained with the use of B-mode are of primary importance. Comparison of the capabilities of the B-mode with two-dimensional scanning and three-dimensional reconstruction indicates a higher resolution of the method with a three-dimensional ultrasound image. The structural features and contour of the wall, as well as the state of its echogenicity, are more clearly recorded, which is of great clinical importance in determining indications for the surgical treatment of patients suffering from pancreatic cancer.

The technique of three-dimensional reconstruction is effective in assessing the condition of the vessel wall and has less clinical significance in evaluating the ultrasound characteristics of the pathological focus. Improving the image of a tumor in B-mode with a three-dimensional reconstruction in comparison with a two-dimensional scan (more clearly visualize the boundaries of the tumor, more clearly define the structural features) is not strictly necessary information to address the question of the resectability of pancreatic cancer.

Such information at the pre-operative stage allows to determine the tactics of patient management and to solve the problem of the possibility of removing the tumor with reconstruction or without reconstruction of the affected segment of the vessel.

Analyzing our material based on the results of a survey of more than 50 patients with focal pancreatic lesions, we came to the conclusion that in order to assess the condition of the wall, the lumen of the vessel, and the question of the possibility of performing surgical treatment and its volume in patients with pancreatic cancer, three-dimensional reconstruction is the presence of a pancreatic tumor that contacts the main vessels.