Ultrasonic diagnosis is a common medical imaging technique used for detecting and diagnosing tumors, including cancer. Ultrasonic waves are high-frequency sound waves that generate images through the reflection of echoes from human tissue. In ultrasound diagnosis, doctors place ultrasound probes on the patient's skin, create images by sending ultrasound waves into the body and receiving echoes. These images can display the location, size, and shape of tumors, helping doctors determine their nature.
The working principle of ultrasound diagnosis
The doctor places the ultrasound probe on the patient's skin, with one or more emitting crystals inside the probe. These crystals generate high-frequency sound waves, typically in the frequency range of 2-18 MHz. The emitted sound waves enter human tissue through the skin. When sound waves encounter tissue interfaces with different densities or acoustic impedances (changes in sound wave propagation speed), a portion of the sound waves will be reflected back, while another portion will continue to pass through the tissue. The receiving crystal inside the probe will receive the reflected sound wave signal. These signals will be converted into electrical signals and transmitted to the computer system for processing. The computer system generates images based on the time delay and intensity of the echo of the received sound wave signal. The echo characteristics of different organizations will present different brightness and color on the image. The generated image will be displayed on the screen, and doctors can identify and analyze tumors or other abnormal conditions by observing the image. The principle of ultrasound diagnosis is based on the propagation and reflection characteristics of sound waves in tissues. Due to the different acoustic impedances of different organizations, sound waves will reflect and scatter at the tissue interface. By analyzing these echo signals, ultrasound diagnosis can provide information about tissue structure, blood flow, and abnormal lesions.
The basic characteristics of ultrasound diagnosis for several common tumors
Primary liver cancer
Primary liver cancer refers to malignant tumors originating from liver tissue. Ultrasonic diagnosis is one of the most commonly used and effective methods for screening and diagnosing liver cancer. Primary liver cancer usually presents as a single or multiple masses, with irregular morphology, blurred boundaries, and presenting as nodular or fused nodules. The echo characteristics of primary liver cancer are diverse and can be divided into uniform echo type. The echo inside the tumor is uniform and consistent, similar to the echo of surrounding normal liver tissue. Uneven echo, the internal echo of the tumor may be uneven, and there may be cystic changes, bleeding, necrosis, etc. Low intensity echo type, with low internal echo in the tumor, may be related to factors such as increased tumor cell density and fibrosis. High echogenicity type, with higher internal echoes within the tumor, may be related to factors such as tight arrangement of tumor cells and abundant blood vessels. Color Doppler flow imaging can evaluate the blood supply of tumors. Primary liver cancer is usually characterized by abundant blood flow around or inside the tumor, with visible vascular tumor like blood flow signals, as well as abnormal blood flow patterns such as blood flow bifurcation and turbulence. Primary liver cancer can infiltrate adjacent liver tissue or bile ducts, and ultrasound examination can observe features such as blurred boundaries between the tumor and surrounding tissues, and dilation of bile ducts. Primary liver cancer is often accompanied by intrahepatic metastasis, and ultrasound examination can detect features such as multiple nodules, nodule fusion, and vascular invasion in the liver. The accuracy of ultrasound diagnosis of liver cancer is influenced by the operator's experience and equipment quality.
Gallbladder cancer
Ultrasound can help detect lumps or abnormal structures within the gallbladder. Gallbladder cancer usually presents as thickening of the gallbladder wall, irregular nodules or masses. In ultrasound images of gallbladder cancer, the gallbladder wall usually shows significant thickening, exceeding 3-4 millimeters. Wall thickening can be uniform or uneven. In ultrasound images of gallbladder cancer, the tumor area usually presents as strong echoes, meaning that the echo intensity is relatively high. This is due to the high cell density of tumor tissue and its strong ability to reflect ultrasound waves. The mass of gallbladder cancer usually presents as an irregular shape, with blurred or irregular boundaries compared to the smooth contour of a normal gallbladder. Ultrasound can also detect other features of gallbladder cancer, such as stones in the gallbladder wall, ulcers in the gallbladder wall, and infiltration of the gallbladder wall.
Pancreatic cancer
pancreatic cancer usually presents as a lumpy or nodular abnormal mass with irregular size and shape. Tumors often have unclear boundaries with surrounding tissues, and sometimes cystic changes, necrosis, or bleeding can be seen. The echo characteristics of pancreatic cancer are diverse, depending on the histological composition and pathological type of the tumor. Common echo manifestations include low echo, moderate echo, high echo, and mixed echo. Low echo areas may indicate a substantial part of the tumor, while high echo areas may indicate calcification or fibrosis. Pancreatic cancer is often accompanied by abnormal blood supply. Ultrasound Doppler can evaluate the blood flow of tumors, such as blood flow velocity, blood flow morphology, and vascular distribution. Pancreatic cancer often presents with dilation of blood vessels around the tumor, rich blood flow or abnormal angiogenesis. Pancreatic cancer may invade adjacent blood vessels, lymph nodes and surrounding tissues. Ultrasound can evaluate the relationship between tumors and adjacent organs, such as pancreatic head cancer that can involve the common bile duct and gallbladder, and pancreatic body and tail cancer that can invade the spleen and stomach. Advanced pancreatic cancer can cause ascites accumulation, and ultrasound can detect the presence and extent of ascites. In addition, ultrasound can also evaluate whether there are metastatic lesions in the liver, lungs, and other abdominal organs.
Renal tumors typically present as abnormal areas in the form of clusters or nodules. The shape of a tumor can be circular, elliptical, or irregular. The internal echoes of renal tumors can have various manifestations. Benign tumors usually present as uniform hypoechoic or isoechoic, while malignant tumors may present as uneven hyperechoic, mixed echoic, or cystic echoic. The boundary of renal tumors can be clear or blurred. Benign tumors usually have clear boundaries, while the boundaries of malignant tumors may be blurred, sometimes with spiky edges visible. Ultrasound Doppler technology can evaluate the blood flow of renal tumors. Malignant tumors typically have abundant blood flow supply, characterized by enhanced blood flow signals and abundant blood vessels. Ultrasound examination can measure the size of renal tumors. The size of a tumor can be measured by diameter or volume.
Ovarian cancer
Ovarian cancer typically presents as a cystic solid mixed mass, characterized by a combination of cystic and solid regions. The internal echoes of cystic ovarian cancer are usually uneven and may present as cloudy internal echoes or cystic wall nodules. Ultrasound Doppler technology can evaluate the blood flow of ovarian tumors. In ovarian cancer, tumor blood flow usually presents irregular blood flow distribution, and there may be areas with abnormal enhancement or lack of blood flow. The cystic area of ovarian cancer is often accompanied by the formation of wall nodules or septa. Ovarian cancer typically leads to abnormal ovarian mobility, where the position of the ovary is more likely to change compared to its normal position.