Imaging examinations of liver lesions are currently used mainly for the detection of liver cancer, especially in patients suffering from various types of viral hepatitis and cirrhosis, or for the differentiation of liver cancer from certain related diseases. The imaging means involved: ultrasonography, CT, MRI, angiography, PET-CT, etc. Which method is the best one to choose? Especially, the detection of early cancer foci and the differentiation of cancer foci from similar non-cancerous foci. In practice, we often encounter the situation like this: “I found a lesion in my liver during a physical examination, how can I confirm the diagnosis? I had a CT and MRI, but they both failed to confirm the diagnosis. This phenomenon is often encountered, you ask some doctors, he may not be clear, may finally recommend you to do a liver puncture biopsy (i.e. stick a needle into it to extract something from it for laboratory testing). Ultrasound: the most commonly used, simple, economical, some very high level of ultrasound diagnostic experts can detect early lesions and in the differential diagnosis of lesions is very profound. However, in practice, ultrasound is generally used as a screening tool. Repeatability of ultrasound examination is poor, meaning that the examination results vary from time to time and from doctor to doctor, because of the influence of the examiner’s technique and skill, as well as the limit of the examination principle of ultrasound itself. For example, a liver tumor is suspected to be a liver tumor in CT examination, and a malignant liver tumor (bile duct cancer) is diagnosed in MRI examination, but no abnormality is seen in ultrasound examination. I took the MRI picture and asked the ultrasound specialist to re-examine it, but the result still did not show any lesion. The reason is that there is no echogenic difference between the lesion and the normal liver background on the ultrasound image (see figure). With the MRI image: The size of the liver malignant tumor diagnosed by MRI is 3.8 cm, but it cannot be detected by ultrasound, which is not a missed diagnosis, but the limit of application of ultrasound (i.e. because of the similarity of the sonogram interface between the lesion and the normal liver tissue, this cannot be distinguished by ultrasound). Another case of missed diagnosis of renal tumor by ultrasound (here is an example of objective defects of ultrasound in tumor examination with renal tumor as an example): In one patient, MRI examination revealed a convex tumor in the right posterior upper kidney cortex, about 3.5 cm, in which there was more fat or degenerative fat (see figure), which was suspected to be a misshapen tumor, and no lesion was found in the previous three ultrasound examinations from 2012-2013. Therefore, we specially invited the ultrasound diagnostic specialist to give a review, and we were told that there was a tumor in the right kidney, and the ultrasound examination replied that no abnormality was found and asked about the specific location of the lesion. I brought the MR film to the scene and also watched it together, and the tumor was seen in this ultrasound. Why couldn’t I see it before? The ultrasonographer answered 3 points: the lesion is located in the dorsal side of the kidney and close to the psoas major muscle, the location is very deep; and the lesion contains more fat mixed with perirenal fat; the examination needs special angle and technique, otherwise it cannot be found. This case suggests that for certain organ lesions, ultrasound examination has certain limits and needs to be treated objectively. CT examination: the previous ordinary CT has been eliminated, the current CT refers to spiral CT, spiral CT has many grades, such as single layer, 4 layers, 8 layers, 16 layers, 64 layers, 128 layers, etc., the higher end, the faster the scanning speed, and accept less radiation. The current CT technology mainly has irreplaceable advantages in lung examination and coronary angiography, but the examination of liver is not as good as MRI, especially the leakage rate of small lesions is very high. If only CT plain scan of the liver is used to search for lesions, its value is not as good as ultrasound. CT iodine oil imaging can detect very small tumors and be used to localize them during radiofrequency ablation therapy, but it also cannot detect and diagnose them if they are tumors with a lack of blood supply. PET-CT (PET CT): It is mainly used for the search of malignant tumors, such as gastric cancer, to see if there are metastases in other parts of the body before surgery; the number of malignant tumors distributed among the body; the evaluation of the efficacy of malignant tumors after treatment, etc. Although sensitive, the specificity is poor, for example, some inflammatory lesions or certain benign lesions (injury, hemangioma, etc.) can behave quite like cancerous tumors, and some of them are not easily distinguishable. Therefore, this method is mostly used as an adjunctive method with other imaging examinations. 1. According to domestic and foreign literature, for primary hepatocellular carcinoma, the positive rate of PET-CT imaging is 50-60%, which is not too high, because the tracer generally used at present is 18-FDG, and part of well-differentiated hepatocellular carcinoma has not too high uptake of 18-FDG, which is close to normal hepatocytes; another part of poorly differentiated hepatocellular carcinoma has a high uptake of 18-FDG, which is close to normal hepatocytes. The other part of poorly differentiated hepatocellular carcinoma, with higher malignancy, has higher uptake of 18-FDG, which can be clearly diagnosed. 2. Magnetic resonance imaging (MRI): As far as the patient’s questions cited at the beginning of this article are concerned, MRI is an effective diagnostic method. Many people, including well-known scholars, think that MRI is difficult to diagnose microscopic liver cancer below 1.0 cm (MRI equipment before 2000 was limited by hardware and software technology, and abdominal images, especially for smaller lesions, were not as good as high-end CT), but in our clinical practice, we use the latest MRI machines, either 1.5T or 3.0T (of course, 3.0T is better), which are really valuable for diagnosing microscopic liver cancer. It does have a high application value. In the past two years, we have diagnosed nearly 20 1.0cm cancer foci with 3.0T, and the treatment effect is very good. The effect of our MRI examination has been praised by experts from Beijing Hospital of Ministry of Health, 301 Hospital, Peking Union Medical College Hospital, Beijing Youan Hospital, etc. Director Liu Wei, an interventional therapist from Peking Union Medical College Hospital, has treated many cases of microscopic liver cancer diagnosed by us. It should be noted that MR examinations need to be standardized. Our MRI upper abdomen examination for each patient requires that five basic sequences of scans must be completed (designed according to the guidance of Prof. Yang Zhenghan of Beijing Hospital), and multiple phases of dynamic enhancement must be done as needed. Otherwise, a substandard MRI is unlikely to meet the diagnostic requirements, much less make a correct diagnosis. The article of my thesis “3.0T MR detection and diagnosis of 1.0cm micro liver cancer application experience” was published in the core journal “Journal of Practical Radiology”. (It should be noted that (1) the MRI machine software and hardware should meet the examination requirements, because some manufacturers’ equipment does have poor performance; (2) the scans performed are strictly in accordance with the requirements and cannot be omitted) Outpatient sighting: In the afternoon of May 22, 2014, when I was out of the clinic, an elderly man entered and asked, “I want to register a number of Director Yang” “Do you see patients?” “I don’t see patients” “Why do you want to register if you don’t see patients?” “I want to get to know him and meet him.” It turned out that he was specifically trying to thank. His last name was Li, a patient from Langfang, and according to his name in the diagnostic imaging workstation pulled up his image data on December 27, 2013 (image number: 492084), MR diagnosis: microscopic liver cancer (5mm) (see the picture below). Mr. Li told that he took the film and diagnosis to Beijing Youan Hospital for treatment the day after he got the diagnosis. When he saw the MRI diagnosis, the doctors at Youan found it incredible that the MRI dared to make a direct diagnosis of liver cancer for such a small lesion? He said he could not believe it. The next test results confirmed the diagnosis of liver cancer and treatment was done. When he was discharged from the hospital, Mr. Li asked Dr. Youan if the MR diagnosis was correct. The doctor nodded his head in admiration and said he had never seen such a high level of diagnostic imaging. Attachment: CT plain scan did not find clear lesions Nuclear magnetic T2WI saw clear nodules (arrows) Nuclear magnetic DWI and enhancement scan saw clear lesions (arrows), after comprehensive analysis MR diagnosed microscopic hepatocellular carcinoma In summary, my suggestions for the issues involved in the title of this article are: 1. Search for early liver cancer foci (high-risk groups, such as those with cirrhosis, hepatitis B, postoperative hepatocellular carcinoma, elevated methemoglobin, etc.) masses or for diagnosis and differentiation of nodular lesions, standardized MRI examination is recommended to be practical and effective. 2. When ultrasound examination reveals or suspects a lesion in the liver but cannot confirm the diagnosis, it is recommended to choose standard MRI examination. CT oil iodography is better when used in conjunction with MRI. 4.PET-CT (PET-CT) is only about half sensitive for primary liver cancer and is only suitable for cancer foci with high malignancy.