2017年 · 第51卷第10期

The emergence of MRI is a milestone event in the development of modern medicine. Not only has the level of clinical diagnosis of diseases made revolutionary progress, but also greatly promoted the understanding of disease mechanism and promoted the progress of biomedical research. Because of the special physical (high magnetic field) and biological effects of MRI, its application safety management has been attracting much attention. The American College of Radiology issued safety specifications for MRI applications in 2007 and 2013, respectively^[1,2]； In China, there are also related review reports and regulations of management departments involving MRI safety management content^[3,4]。

coronary computed tomographic angiography (CCTA) began to be applied internationally in 2003, marking the beginning of this technique in the diagnosis of coronary artery disease^[1]。 International multi-center studies have successively proved that CCTA is safe and effective^[2,3,4]。 However, the problems of high radiation dose and irregular operation of this technique have gradually been exposed^[5]。 Therefore, in the past 10 years, experts at home and abroad have published more than 30 important documents in the form of expert consensus, scientific statement and guideline, which have played an important role in promoting the standardized application of CCTA in the world^[6,7,8]。

MRI is a widely used imaging examination method in clinical practice. Compared with X-ray and CT, MRI has no ionizing radiation and is considered as a safe imaging method. In fact, there are many potential risks in the MRI environment, which may cause harm to the subject, accompanying family members, medical staff and other workers present in the MRI site (such as security guards, cleaning staff, etc.). Therefore, MRI safety management is worth paying attention to. Experts from the Quality Management and Safety Management Group and the Magnetic Resonance Imaging Group of the Radiology Branch of Chinese Medical Association have formulated this edition of the Chinese Expert Consensus on MRI Safety Management on the basis of referring to domestic and foreign MRI safety standards and related literatures, and combined with the actual situation in China, aiming to improve the awareness of MRI safety management and the level of MRI safety management.

Since 2003, the internationally recognized 64-slice CT has been used in coronary CT angiography (CCTA) for more than 10 years, and has become the main non-invasive imaging tool for diagnosing coronary artery disease. In recent years, the imaging capability of CT equipment has been further improved, and the landmark progress is reflected in the further improvement of CCTA image quality, while the radiation dose of patients has been greatly reduced. In this field, domestic and foreign experts have accumulated some application experience and medical research evidence, and published many expert consensus or guidelines^{[1,2,3,4,5,6,7,8,9]}But all lack detailed technical operation guidelines.

Rosai-Dorfman disease (RDD) is a benign histiocytic disease of unknown origin, first reported by Destombes in 1965 and detailed and referred to as sinus histiocytosis with giant lymphadenopathy by Rosai and Dorfman in 1969^[1]However, because there is no extranodal lymphatic sinus, the name RDD is currently more common. Because the disease is rare in clinic and has diverse manifestations, it is easy to be misdiagnosed. The author collected the imaging data of 4 patients and retrospectively analyzed their CT and MRI characteristics in combination with the literature to improve the understanding of this disease.

A 4-year-old daughter was admitted to hospital on December 23, 2016 because she was found to occupy intracranial space for more than 3 years, suffering from repeated headache and dizziness for 1 month. Three years ago, the child suffered from paroxysmal confusion with limb twitching 2 months ago. MRI of the head showed an irregular mass around the midbrain aqueduct, midbrain and supracerebellar vermis.₁WI showed low signal, T₂WI showed a high signal, and the liquid attenuation inversion recovery (FLAIR) sequence T₂WI showed low signal in the solid part, lower signal in the cystic part, and high signal in the peripheral half-moon shape. The lesion boundary was clear, and the size was about 1.9 cm ×1.5 cm ×2.0 cm. The corresponding midbrain aqueduct was slightly compressed and narrowed. There was no enhancement of the mass after enhancement (Figure 1,Figure 2,Figure 3）。 The lesion was considered as a tumor and observed because the lesion was small. After discharge, the patient did not have any discomfort such as limb twitching. One month ago, the patient had headache, dizziness, accompanied by nausea and vomiting without obvious trigger, and went to our hospital again. Laboratory tests showed no abnormalities. Re-examination of the skull MRI still showed irregular mass shadows around the midbrain aqueduct, midbrain and supracerebellar vermis, T₁WI showed low signal, T₂WI showed hyperintensity shadow, FLAIR sequence showed solid part hyperintensity, cystic part hypointensity, the size was about 2.6 cm ×2.5 cm ×3.5 cm, the lesion was significantly larger than before, the center of the lesion showed annular enhancement after enhancement, the corresponding midbrain aqueduct was narrowed under compression, and the supratentorial ventricular system was significantly enlarged (Figure 4,Figure 5,Figure 6,Figure 7）。

The child was a 9-year-old male. The right occipital subscalp mass was found for more than 5 months, and I came to our hospital in July 2015. The mobility of the tumor is not good, not accompanied by tenderness, and it is tough to touch. Laboratory tests and neurological tests showed no abnormalities.

The patient was a 30-year-old male. He was admitted to the hospital for "finding a mass in the left elbow with sore swelling for several years after activity". A few years ago, the patient found a hard fixed mass in his left elbow. After moving, he felt soreness and discomfort in his left elbow. He went to the local hospital for treatment. X-ray examination showed a left ulnar bone tumor, which was unknown and was not treated. Recently, the patient consciously felt that the mass in his left elbow had become obviously larger, and he felt obvious discomfort. He went to our outpatient clinic more than 3 months ago. Physical examination showed a subcutaneous bulge of about 6.0 cm ×4.0 cm ×1.5 cm below the olecranon on the dorsal side of the left elbow, which was hard, fixed, with poor borders and no tenderness. The range of motion of the elbow joint is 30° ~120°, and the extension of the elbow is slightly limited. No obvious abnormalities were found in the laboratory blood routine. CT of left elbow joint showed entophageal-like bone destruction and cloud-like osteogenic changes in the proximal left ulna. Patchy high-density shadows were also seen in the bone destruction area, and soft tissue mass shadows were seen around it. No obvious periosteal hyperplasia was observed. The lesion range was about 6.9 cm ×4.8 cm. The CT value of high-density area was about 78 HU, and the CT value of soft tissue mass area was about 45 HU (Figure 1）。 MRI showed a patchy abnormal signal shadow in the proximal left ulna, about 6.9 cm ×5.8 cm ×4.9 cm, T₁WI is dominated by constant low signals (Figure 2）。 Pressure fat T₂WI showed high and low confounding signals (Figure 3), bone destruction of the proximal ulna. Pressure fat T₁WI enhanced scan showed circular enhancement around the lesion (Figure 4), the surrounding tissue showed pressure changes. Surgical findings: An incision of about 15.0 cm in length was made on the posteromedial side of the left elbow joint, revealing the proximal segment of the left ulna and olecranon, and the cortex of the proximal ulna to the olecranon was destroyed, with a mass of about 10.0 cm ×8.0 cm ×5.0 cm occupied. The boundary of the mass was clear and the texture was tough, so it was completely resected. Tumor histopathological examination: routine pathology of the proximal tissue of the left ulna. Under the microscope, spindle cells with large central degeneration, necrosis and calcification, active nuclear division, tumor cells invading the surrounding muscle tissue (Figure 5）。 Immunopathology: B-chain protein (b-Catenin), Desmin (Desmin), actin (SMA), leukocyte surface differentiation antigen (CD) 56, S-100, MBP, CD34, B lymphocyte-2 (Bcl-2) were all negative, and the cell proliferation index (Ki-67) was 30% ~60%, which was considered as sclerosing epithelioid fibrosarcoma (SEF).

Child girl, 6 d. He was admitted to the hospital on August 10, 2016 due to shortness of breath and cyanosis for 6 days after birth. The child was born by cesarean section at 40 weeks due to macrosomia. The birth Apgar score was 8-8-10, respectively. He developed shortness of breath, cyanosis, moaning, inspiratory dyspnea 1 h after birth, and a large shadow of the left lung was found on the chest X-ray (Figure 1）。 Physical examination with tracheal intubation and ventilator showed that the breathing sound of both lungs was coarse, and a little phlegm sound could be heard. Laboratory tests showed no obvious exception.

A 53-year-old female suffered from intermittent precordial pain for 2 years without obvious trigger. She was admitted to the hospital on November 21, 2016 because the local hospital's color ultrasound showed "solid mass in the right ventricle". Physical examination showed no clear positive signs. All laboratory tests, including female tumor markers, thyroid function and myocardial injury markers, showed no abnormalities. Electrocardiogram revealing incomplete right ventricular block. Color Doppler ultrasound of the neck showed that the position and shape of the thyroid were normal. Color ultrasound showed a solid round mass in the right ventricle, 4.7 cm ×4.4 cm in size, with clear boundaries and uneven internal echoes. The lesion seemed to be pedicled and attached to the interventricular septum, and did not move with the cardiac cycle. Mild regurgitation was seen at the tricuspid valve orifice. CT scan showed a slightly higher density shadow with uneven circular density in the right ventricle, about 4.8 cm ×4.1 cm in size, with a CT value of 26~68 HU, and an unclear boundary with the interventricular septum. After enhancement, it showed uneven and obvious enhancement, with a CT value of 77~136 HU. A thickened branch vessel in the proximal segment of the left anterior descending coronary artery travels to the lesion area (Figure 1，Figure 2）。

A 52-year-old male was admitted to the hospital due to foreign body sensation in the pharynx and hoarseness for more than 1 month, and dyspnea for 15 days. Physical examination: pharyngeal mucosa is congested, soft palate is lifted symmetrically, bilateral tonsils are not swollen, lymphoid follicular hyperplasia in the posterior pharyngeal wall, and no mass and swollen lymph nodes are palpable in the neck. Fiber laryngoscopy revealed: subglottic stenosis. Laboratory tests are not special.

A 56-year-old female was admitted for 10 years due to swelling of the left lower limb. Physical examination: the left lower limb was swollen throughout the course, and the circumference of the left patellar tubercle at 15 cm proximal was 8 cm longer than that of the contralateral, and the circumference of the left patellar tubercle at 15 cm distal was 6 cm longer than that of the contralateral. Compression edema of ankle and dorsal foot, no tortuous vascular mass and pigmentation on the superficial surface, and no abnormality in the contralateral limb. Venous ultrasound of lower extremities showed no venous thrombosis. Urine red blood cells were positive (+ + +) and protein negative. Enhanced abdominal CT showed a retroaortic left renal vein with compression of the left renal vein (Figure 1), distal segment dilatation (Figure 2）。 Lower extremity venography showed compression of the left iliac vein and formation of peripheral collateral circulation (Figure 3), performed iliac venoplasty. Ultrasound-guided puncture of the left popliteal vein, systemic heparinization after insertion of a vascular sheath, balloon dilatation of the left compressed iliac vein, implantation of a 12 mm ×80 mm Wallstent stent, re-angiography showed disappearance of stenosis and disappearance of peripheral collateral circulation (Figure 4）。 Postoperative patients were given warfarin orally, and the adjusted international standardized ratio was 2.0~3.0. After 6 months of follow-up, the swelling of the lower limbs of the patient disappeared, and there was still microscopic hematuria, which was not significantly increased compared with before, and there was no proteinuria and low back pain and discomfort.

The patient was a 36-year-old female. Five years ago, abdominal CT in an external hospital showed a lesion with a maximum diameter of 2 cm and was diagnosed as hepatic hemangioma. Abdominal B-ultrasound 1 year ago found mixed hypoechoic mass in the liver, with the largest cross section of 61 cm ×35 mm, the specifics of which are unknown. Physical examination: Obvious tenderness in the lower abdomen, mild rebound pain, and no obvious abnormalities. Laboratory tests are not special.

prostate cancer (PCa) is a common malignant tumor in men, ranking second in male cancer mortality in the United States^[1]。 Although the prevalence and death rate of prostate cancer in China are far lower than those in Europe and America, they have shown a continuous increasing trend in recent years^[2]。 Because MRI has good soft tissue resolution, it can clearly show the internal and surrounding tissue structure of prostate, and it has become the first choice of imaging examination method for early diagnosis of prostate cancer. There is a large overlap of ADC values in prostate cancer, prostatic hyperplasia and normal prostate tissues. diffusion kurtosis imaging (DKI) was developed in 2005 by Jensen et al.^[3]First proposed, is an extension of diffusion tensor imaging (DTI) and DWI. DKI was initially used primarily in the neural field^[4,5,6,7]With the prominent role of DKI in tumor identification and grading, this technology has gradually been applied to prostate and other tissues and organs^[8,9,10,11]。 The author reviews the research progress of DKI in the diagnosis and classification of prostate cancer.