The first edition of Liver Imaging Reporting and Data System (LI-RADS) is proposed by American College of Radiology (ACR) in 2011 for diagnosis of hepatocellular carcinoma (HCC) in at-risk patients.It is created to standardize the reporting and data collection of CT and MR imaging for HCC to classify observation.Since it had been announced,many validation studies had been performed and the first edition of LI-RADS had been revised in 2013 and 2014,respectively.In July 2017,the latest revision (LI-RADS(R)v2017) has just been launched more reasonable and practical with new algorithms,new revised categories for LI-RADS and new criteria for many imaging features.The changes of CT/MR in LIRADS(R) v2017 were interpretated in this article.

Placental implantation (PI) is a serious complication of obstetrics and gynecology,which threatens the safety of the mothers and children.Prenatal ultrasound has become the preferred imaging method due to its universality,ecnomic ly and high sensitivity,but the diagnostic efficacy of the indicators is still controversial.The diagnostic value and advantages of various indicators of prenatal ultrasound in the diagnosis of PI were reviewed in this article.

The applications are narrow in the scope of conventional ultrasound-guided lung biopsy due to the restriction of techniques.With the development and application of new ultrasonic techniques,a number of novel ultrasound-guided methods are applied in lung biopsy,which not only improv the accuracy of diagnosis,but also extend to special locations where conventional methods are difficult to obtain samples.The application of new ultrasonic technology in lung biopsy were reviewed in this article.

The central nervous system disease and musculoskeletal diseases often involve skeletal muscles.Quantitative evaluation of strength and hardness of a single muscle accurately and rapidly are basis for causation analysis of movement dysfunction.Real-time shear wave elastography (SWE) is a new ultrasonic imaging technique developed in recent years,and still has a preliminary application in the skeletal muscle system.The application and research progresses of SWE in auxiliary diagnosis of disease in skeletal muscles were reviewed in this article.

Rapid development of MRI has gradually evolved from morphological imaging to functional imaging.Functional MRI can provide pathophysiological information more than morphological information,such as molecular and metabolic information.The application value of functional MRI in cervical cancer has become a hotspot in recent years.The research progresses of functional MRI in cervical cancer were reviewed in this article.

MRI is the first choice for preoperative evaluation of rectal cancer.It can not only provide high accuracy for T and N stage,but can also apply important factors related to the prognosis,such as extramural depth,extramural venous invasion and circumferential resection margin.Moreover,it is also promising for predicting therapeutic effects of neoaduvant chemoradiotherapy.MRI preoperative evaluation indexes and new techniques in rectal cancer were reviewed in this paper.

Carotid plaques are closely related to strokes or transient ischemic attacks.MRI plays an important role in the diagnosis and evaluation of prognosis.At present,the study of carotid plaque MRI is mainly focused on the evaluation of plaque stability and pathological mechanism.The research progresses of development mechanism and MR techniques in the diagnosis of carotid plaque were reviewed in this article.

Ultrasound elastography technique is a novel method that can assess the elasticity of tissues accurately,noninvasively and repeatablely.Children with cerebral palsy which is main of spastic type can be characterized by increased muscle stiffness and increased muscle tone of affected muscle,limited physical activity and different postures while involving different skeletal muscles.In recent years,botulinum toxin has been introduced as a selective treatment approach for spasticity in children with cerebral palsy,but the noninvasive,economic,convenient and quantifiable method to evaluate the therapeutic effect of botulinum toxin injections is absent.Ultrasound elastography technique can be used for assistance in assessing the degree of affected muscle and the therapeutic effect in the diagnosis and treatment of cerebral palsy.The application of ultrasound elastography technique in children with cerebral palsy were reviewed in this article.

The mutation of isocitrate dehydrogenase (IDH) gene is associated with gliomagenesis.It has also significant positive effects on survival and chemosensitivity in comparison with IDH wild-type glioma.Being an important energetic metabolism enzyme,mutation of IDH results in changes of microstructures and metabolism.Quantitative multimodality MR imaging has ability to obtain imaging biomarkers about microstructural,physiologic and functional information,which demonstrates the promises to assess IDH gene status in vivo.The progresses of association between quantitative multimodality MRI features and IDH genesmutations in glioma were reviewed in this paper.

Objective To assess image quality of adaptive statistical iterative reconstruction (ASIR),conventional modelbased iterative reconstruction (MBIRc) and a new lung-specific setting (MBIRRP20 and MBIRNR40) from the new version of model-based iterative reconstruction (MBIRn) in submillisievert chest CT comparing with ASIR in standard-dose.Methods Two chest CT examinations were performed with standard-dose and low-dose in 30 patients.Low-dose CT images were reconstructed with ASIR,MBIRc and MBIRn,while standard-dose CT images were reconstructed with ASIR only.Objective image noise and SNR were measured on the same part from the back muscle and subcutaneous fat which located at the level of thoracic entry,trachea carina and hepatic portal.Image quality of lung,mediastinum and upper abdomen structures were evaluated on a 5-point scale.The results were compared with one-way ANOVA and Wilcoxon signed-rank tests.Results The effective dose equivalent for standard-dose CT was (3.01 ± 1.89) mSv,compared with (0.88 ± 0.83) mSv for low dose CT,which decreased by 70.76％.The mean image noise for low-dose MBIRNR40 was significantly lower than that of conventional-dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The mean SNR for low-dose MRIRNR40 was significant ly higher than that of conventional dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The subjective image noise score was significantly lower than that of ASIR and MBIRc,and the score of sharpness of details of the structures score for low dose MBIRn was significantly better than that of the ASIR and MBIRc (P＜0.05).Conclusion MBIRNR40 can significantly reduce image noise and improve SNR compared to ASIR and MBIRc in low-dose,even better than ASIR in standard dose,which reduce radiation dose by about 70％.In low-dose,MBIRPP20 can well display lung structures,and MBIRNR40 can display mediastinal and the upper abdominal structures.