2017年 · 第51卷第11期

With the widespread application of CT, the problem of ionizing radiation has attracted more and more attention. Reducing the radiation dose of CT is a hot topic in clinical research, and low radiation dose CT examination is the general trend. The CT radiation dose can be reduced by reducing the tube voltage, reducing the tube current and increasing the pitch^[1,2,3,4]But the excessive pursuit of low radiation dose is bound to have an impact on the image quality. In order to deal with the accumulated high radiation dose problem caused by the increasing number of CT examinations, and thus balance the relationship between radiation dose and image quality, relevant International institutions, such as the United Nations Scientific Committee on the Effects of Atomic Radiation, the International Commission on Radiological Protection (ICRP), the International Atomic Energy Agency and WHO, cooperated to obtain evidence-based medical evidence for medical radiation Protection, and established and used CT radiation dose diagnostic reference levels (DRL) to obtain the best balance between radiation dose and image quality. At present, the establishment of DRL has become the universal demand of CT radiation protection.

Compared with low field strength, 3.0 T MRI has good soft tissue resolution and signal-to-noise ratio, which provides an important imaging method for studying cervical lesions. Frequency-selective fat suppression (FS) is one of the important techniques for neck MRI. However, due to the irregular geometry of the neck and the difference of magnetic sensitivity at the air-tissue interface, the local magnetic field is not uniform, which affects the display of neck tissue and lesions^[1,2]。 We used fast spin echo (FS TSE) T on volunteer routine MRI scans and neck-filled rice bag scans₁WI and T₂WI images were comparatively studied to evaluate the value of neck-filled rice bags in eliminating artifacts, improving lipid pressure uniformity and improving imaging quality in 3.0 T MRI neck FS sequence scans.

Extrahepatic portal vein embolism is one of the common causes of portal hypertension in children^[1]Portal hypertension includes prehepatic, intrahepatic and retrohepatic types, and the incidence of intrahepatic and retrohepatic portal hypertension in children is low. cavernous transformation of the portal vein (CTPV) is more common in children, accounting for about 40% of prehepatic portal hypertension in children^[2]。 Its etiology is mostly primary^[3]。 Superior mesenteric vein-left portal vein bypass shunt is currently widely recognized as a treatment option for CTPV in children, also known as Rex. Its principle is to cross the embolized blood vessel, intercept the normal body vein, anastomose the superior mesenteric vein with the left branch of the intrahepatic portal vein, and restore the normal blood flow perfusion of the liver^[4,5]。 The main points of preoperative evaluation of this procedure are to clarify whether the left and right confluences of intrahepatic portal veins are patent, as well as the running of the left branch of portal vein and the inner diameter of the tube. Portal hypertension has typical diagnostic signs on enhanced CT and MR, but intrahepatic portal vein imaging is poor (especially in children with CTPV, the main trunk of hepatic portal vein is partially or completely occluded). Therefore, CT and MR have limitations in the preoperative evaluation of portal hypertension in children. Transhepatic venous wedge angiography can clearly show the status of intrahepatic portal vein, which is helpful for the selection of surgical methods for children with portal hypertension. The authors collected the clinical and imaging data of children with portal hypertension who underwent wedge angiography and indirect portal angiography in our hospital in recent years, and are reported as follows.

The child, a 4-month-old male, was seen in our hospital on August 10, 2013 because he found that the child could not raise his head. Lumbar puncture showed slightly higher intracranial pressure, and all other laboratory tests were normal. The first MRI examination of the patient showed diffuse nodular thickening of bilateral cerebellar hemisphere cortex and hyperintensity of DWI (Figure 1), the enhanced scan was significantly uniformly enhanced (Figure 2，Figure 3), the patient's family decided not to perform any treatment follow-up observation due to the diffuse extent of the lesion and the difficulty of surgery. One year later, reexamination found that the cerebellar hemisphere signal returned to normal, and only a nodular abnormal enhancement was seen (Figure 4）。 Considering the site of onset and signal characteristics of children, considering neoplastic lesions, combined with age, it is considered that medulloblastoma is more likely. Half a year later, the child was re-examined, and CT showed a massive high-density shadow of the cerebellar vermis (Figure 5), MRI showed a slightly longer T₁Slightly longer T₂Signal (Figure 6), multiple spotty longer T can be seen inside the lesion₂Signal shadow, DWI showed obvious high signal, and the solid components of the lesion were obviously uniformly enhanced on enhanced scan (Figure 7）。

The patient was a 45-year-old female. There was no obvious trigger for intermittent anterior chest pain, chest tightness with back pain for more than 3 years. He was diagnosed as coronary atherosclerosis by coronary angiography in a local hospital, and the symptoms were relieved after oral nitroglycerin treatment. In the past half month, the above symptoms aggravated, and the plain CT scan of the chest in an external hospital showed mediastinal mass, so he was admitted to the hospital on November 7, 2016 for further diagnosis and treatment. Previous: Hypertension for 4 years, good blood pressure control with oral antihypertensive drugs. Physical examination: general condition, blood routine, liver and kidney function were not found abnormal.

Example 1Female, 26 years old. Menopause for 2 months, abdominal distension for 5 d. Laboratory tests: CA125 was 233.3 IU/ml (normal reference value 0-35.0 IU/ml) and serum calcium was 3.51 mmol/L (normal reference value 2.25-2.75 mmol/L). MRI examination: 10.2 cm ×11.0 cm ×15.5 cm cystic-solid mass in the posterior and upper part of the uterus, which was lobulated, with multiple hemorrhagic foci and necrotic areas, T₁WI showed isoconfounding and low confounding signals with patch-like hyperintensity (Figure 1), T₂WI showed unequal confounding signals (Figure 2), DWI showed a non-uniform high signal (Figure 3）。 Heterogeneous strengthening of the solid part after strengthening (Figure 4), no abnormality was observed in the right ovary, and a malignant tumor originating from the left ovary was considered. During the operation, the left ovarian mass showed a rupture on the surface, the cross section was dark red, multilocular separation, and it was cystic-solid. A large amount of dark red fluid was seen in the cystic part, and the solid part showed fish-like changes and was tough in texture. Microscopically, small, round tumor cells were diffusely distributed with tightly arranged cells with less stroma (Figure 5）。 Immunohistochemistry: Transcription factor FOXL2, tumor suppressor gene WT1, vimentin, CD99, and neuron-specific enolase (NSE) were all positive. Pathological diagnosis: small cell carcinoma of the ovary (SCCO) (hypercalcemia type). After chemotherapy twice, recurrence and metastasis occurred 2 months after operation, and the tumor progressed and died 4 months after operation.

A 52-year-old male patient. The main cause was abdominal pain for 6 days, aggravated with fever for 1 day, and he was admitted to the hospital on November 18, 2016. Abdominal pain is intermittent dull pain, mainly located below the xiphoid process to the right lower abdomen, with abdominal distension. Body temperature 38.9℃.

The patient was a 49-year-old female. He was admitted to the hospital on November 7, 2014, mainly due to upper abdominal discomfort and ultrasonic examination showing space-occupying liver lesions. Physical examination showed no abnormalities. Laboratory tests: Except for total bilirubin of 41.7 μ mol/L (normal reference value of 5.0~21.0 μ mol/L), no abnormalities were found.

stroke refers to a sudden onset of hypoxic-ischemic disease of brain tissue caused by cerebral blood circulation disorders, which is divided into ischemic and hemorrhagic. It is one of the common causes of death in humans, among which acute ischemic stroke (AIS) exceeds 80%^[1]。 The key to the treatment of AIS is to open the occluded blood vessels as soon as possible. The methods mainly include intravenous thrombolysis, arterial thrombolysis and mechanical thrombectomy. Intravenous recombinant tissue plasminogen activator (rt-PA) is one of the standard therapeutic methods, but it has shortcomings such as narrow time window and many contraindications, and the recanalization effect on large vessel occlusion is also very limited^[2]。 mechanical thrombectomy (MT) has the advantages of fast recanalization and wide indications. With the continuous progress of instruments and technology, it has gradually become an important method for the treatment of AIS.

At present, DWI is the only functional imaging technology that can detect the diffusion movement of water molecules in living tissues noninvasively. Single exponential DWI is fitted by single exponential function, which has the advantages of simple model and fast image reconstruction, and is suitable for rapid diagnosis and screening of clinically related diseases (such as hyperacute cerebral infarction, brain abscess, etc.). At the same time, diffusion weighted whole-body imaging with background body signal suppression (DWIBS), developed on the basis of single exponential diffusion imaging through image mosaic technology, improved signal acquisition method and fat suppression technology, is called "PET-like" because its imaging effect is similar to that of PET^[1]。 DWIBS technology is also of great clinical value in the diagnosis and staging of tumor, evaluation of therapeutic effect and monitoring of tumor recurrence^[2,3]。 diffusion tensor imaging (DTI) reconstructs tissue microstructures using anisotropic diffusion tensors on the basis of single exponential diffusion imaging^[4]。 DTI can reflect the integrity of white matter fibers by using the anisotropy of water molecule diffusion, which is helpful for the diagnosis and grading of tumors, and plays an important role in the diagnosis of Alzheimer's disease, epilepsy and multiple sclerosis. All kinds of tissues of human body have complex and diverse system characteristics. It is difficult to express the complex system characteristics of human body only by simple isotropy or anisotropy, and it is difficult to obtain accurate tissue structure characteristics by single exponential diffusion tensor model. With the in-depth research of diffusion imaging principle, the improvement of hardware technology level and the enhancement of post-processing algorithm performance, and in order to make up for the shortcomings of single exponential diffusion model, a variety of new diffusion models have gradually appeared, and have shown unique advantages in clinical application. According to the principle of diffusion model and the focus of research, the author divided the new diffusion models into three types: diffusion rate type, microstructure type and fiber trend type, and summarized their imaging principle and clinical application.

computer aided diagnosis (CAD) is a new technology applied to image diagnosis with the rapid development of computer technology^[1,2]。 CAD technology is a comprehensive application of digital image processing and pattern recognition. It mainly includes the working modules of image acquisition, image preprocessing, ROI domain segmentation, feature extraction and classification recognition^[3]。 The results of global cancer statistics in 2012 show that breast cancer ranks first in the prevalence of malignant tumors in women^[4]Early detection, early diagnosis and early treatment are the keys to reduce the mortality of breast cancer. At present, the main imaging diagnostic techniques of breast cancer include mammography, ultrasound and dynamic enhanced MRI of breast, etc. The application of CAD technology is beneficial to improve the value of imaging diagnosis of breast cancer. The latest research progress of CAD in mammography, ultrasound and MRI is reviewed, and its development prospect is prospected.

Obesity, a multifactorial chronic metabolic disease, is a risk factor for type 2 diabetes, cardiovascular disease, hypertension, stroke, and multiple cancers^[1]。 Since 1980, the worldwide obese population has quadrupled, and global adult obesity (body mass index>30 kg/m²The proportion has exceeded 10%^[2]。 The WHO estimates that there were about 40 million obese children under the age of 5 worldwide in 2013. Based on current trends, this figure is expected to reach 70 million by 2025^[3]。 More than 1/3 (34.9%) of the population in the United States are obese^[4]。 The overweight rate of Chinese residents is 17.6%, the obesity rate is 5.6%, and the overweight and obese population is close to 1/4 of the total population. Obesity has become an important disease affecting residents' health^[5]Its treatment work is imminent. The treatment of obesity is still a difficult problem, conservative treatment is poor and easy to rebound; Surgical treatment is traumatic and has many complications. bariatric artery embolization (BAE) is a hot research topic at present. The author reviews the progress of BAE in the treatment of obesity.

In recent years, academic misconduct has been increasing. In addition to the paper buying and selling incidents repeatedly exposed by the media, SCI paper withdrawal incidents also frequently occur. At the end of April 2017, Springer's journalsTumor Biology107 papers by Chinese scholars were revoked; On May 8th, Quartz counted the number of papers withdrawn from peer review fraud in the world from 2012 to 2016. The number of withdrawals in mainland China (498 papers) exceeded that of other countries and regions combined. Academic misconduct has once again attracted widespread concern from the international community and Chinese academic circles. Although relevant institutions and organizations in our country have formulated and issued various norms and measures against academic misconduct, such as the Guiding Opinions on Optimizing Academic Environment (promulgated by the General Office of the State Council), the Guide to Academic Norms for Science and Technology in Colleges and Universities, and the Interim Measures of the Chinese Academy of Sciences on Investigation and Handling of Scientific Research Misconduct, the definitions of academic misconduct in various rules and systems are not completely consistent, resulting in different standards and solutions used by editors when judging the nature of academic misconduct in manuscripts. In particular, some manuscripts with academic misconduct problems can still be published in other journals after being rejected by one journal, which happens from time to time. Therefore, how to distinguish academic misconduct, ensure the authenticity of academic papers, better avoid and prevent the appearance of this behavior has important practical significance.