BACKGROUND:Three-dimensional bioprinting technology is the emerging technology in recent years, which is one of the branches of tissue engineering. The three-dimensional bioprinting technology has been used in the reproduction process of in vitro tissues and organs, which has achieved surprising outcomes.
OBJECTIVE:To review the three-dimensional bioprinting technology in terms of its principles, operating steps, relationships with tissue engineering, advantages and chal enges, as wel as clinical applications.
METHODS:The first author did a computer-aided retrieval of the PubMed database, CNKI database, and CQVIP database for articles relevant to three-dimensional bioprinting technology used in tissue engineering published between January 2000 and October 2000. The key words were“three-dimensional bioprinting, tissue engineering, rapid prototyping technology, scaffold materials, selective laser sintering, fuseddeposition modeling, stereolithography”in English and Chinese. Repetitive studies were excluded, and 52 of 79 related literatures were adopted in result analysis.
RESULTS AND CONCLUSION:Three-dimensional bioprinting technology is one of the branches of tissue engineering, which can build a virtual three-dimensional structure layer by layer under the computer-aided design technology, with the help of imaging data information (including CT and MRI). This technology has the advantages of high precision, high building speed, fabrication on demand, and also has the chal enges in engineering mechanics and biological activities. In a word, it is a meaningful and promising technology in clinical application.

Magnetic resonance imaging (MRI), featuring as no ionizing radiation, higher soft tissue resolution and multiplanar imaging, has been widely used in the diagnosis of pediatric tumors. Conventional MRI techniques mainly provide information on morphological information of tumors but cannot display physiological and pathological changes in tumors. In recent years, with rapid development of MRI hardware and software, some functional MRI technologies have been applied in clinical practice and have become an important trend on pediatric oncology. These techniques include perfusion-weighted imaging, diffusion-weighted imaging, magnetic resonance spectroscopy, susceptibility weighted imaging. These new technologies can demonstrate the microstructural information of tumors, which will provide more helpful information for diagnosis, treatment and follow-up in pediatric tumors when combined with conventional MRI techniques.

Hippocampus circuit loop is a neuromechanism about recent memory ability. Many researches have reported the effects of different frequency transcranial magnetic stimulation are different on memory ability associated with hippopotamus in rats, which seems to be damaging in healthy rats, but protective in rats with cerebral ischemia.

Objective To evaluate the clinical diagnostic value and limitation of MRI and contrast enhancement MRA (CE-MRA) in congenital heart disease of children. Methods Three hundred patients with congenital heart disease underwent CE-MRA. 173 were confirmed by operation. The results of MRA and CE-MRA were compared with operation data. Results 196 (86.0%) intracardiac malformation including septal defect and valve anomaly were diagnosed correctly by MRI within 228 abnormalities which were confirmed by operation. 101 (96.2%) extracardiac malformation including great vessels stenosis and anomalous connection were diagnosed correctly by MRI and MRA within 105 abnormalities which were confirmed by operation. Conclusion MRI and CE-MRA are very accurate diagnostic method for extracardiac malformation. CE-MRA is the best sequence for congenital heart disease.

Objective To report 6 cases of congenital heart disease with high origin of coronary artery and to evaluate the imaging method for diagnosis of congenital high origin of coronary artery. Methods Six patients with congenital high origin of coronary artery underwent angiocardiography ,echocardiography ,and 2 patients also underwent magnetic resonance examination. All 6 cases were confirmed by operation. Results All 6 cases were congenital high origin of right coronary artery. Angiocardiography made correct diagnosis in all 6 cases; MRI made the correct diagnosis in 1 of the 2 cases; echocardiography made 1 correct diagnosis. Conclusion Correct diagnosis of congenital high origin of coronary artery was very important for patients with congenital heart disease. Angiocardiography was a very reliable imaging method and MRI can play an important role in preoperative diagnosis of congenital high origin of coronary artery.

Objective To evaluate different angiocardiographic techniques of congenital heart disease in children. Methods 11045 pediatric patients with congenital heart disease were performed angiocardiography using cut film, cine film and digital subtraction angiography(DSA) equipments. Different angiocardiographic techniques were used. Results The diagnostic accuracy of cut film with conventional AP and lateral views was 80.5%,the diagnostic accuracy of cine film with angulated views was 90.0% and the diagnostic accuracy of DSA using non-ionic contrast medium with angulated views was 96.5%. Conclusion Dynamic picture angiography with digital subtraction using non-ionic contrast medium under rapid injection is the key for claiming the high quality imaging diaguosis of congenital heart disease in children.

Objective To compare the feasibility,effectivity and security of modified trabeculectomy in advanced stage angle-close glaucoma with cataract.Methods One hundred and forty-five patients (151 eyes) of advanced stage angle-close glaucoma with cataract were enrolled in this study.Among them,85 patients(91 eyes,observation group) were treated with modified trabeculectomy with the resection of deep scleral resection and 60 patients (60 eyes,control group) were treated with routine trabeculectomy.The visual acuity,intraocular pressure (IOP),type of filtering bleb and postoperative complication were compared.Results There was significant difference in the visual acuity ＜ 0.1,0.4-0.5,＞ 0.5 between after operation for 1 month and before operation in two groups (P ＜ 0.05).but there was no significant difference in the visual acuity 0.1-0.3 (P ＞ 0.05).The IOP before operation in observation group was (29.6 ± 4.1) mmHg (1 mmHg =0.133 kPa),12 months after operation was (13.1 ± 4.9) mmHg,the degree of decrease was (16.6 ± 5.0) mmHg.The IOP before operation in control group was (30.4 ± 6.3) mmHg,12 months after operation was (18.9 ± 3.0) mmHg,the degree of decrease was (10.4 ± 4.0) mmHg.The IOP after operation and the degree of decrease between two groups had significant difference (P ＜ 0.05).The functional filtering bleb(Ⅰ type and Ⅱ type) in observation group was 77 eyes(84.6％,77/91),and 51 eyes(85.0％,51/60) in control group,there was no significant difference (P ＞ 0.05).After operation for 1 month,there was 8 eyes appeared transient hypotony in observation group and 5 eyes in control group,there was no significant difference (P ＞ 0.05).Conclusion The modified trabeculectomy in advanced stage angle-close glaucoma with cataract can reduce IOP more effectively and not increase the intraoperative risk and postoperative complication.

Ischemic stroke is a type of cerebrovascular disease with high morbidity, high mortality and high disability, which brings a huge medical burden to the society. Long non-coding RNA (lncRNA) H19 is closely associated with the pathophysiological mechanisms such as oxidative stress, inflammation, apoptosis, autophagy, and neurogenesis after ischemic stroke. It has received widespread attention in recent years. This article reviews the pathophysiological mechanism of lncRNA H19 in ischemic stroke, in order to provide new ideas for the diagnosis and treatment of ischemic stroke.

Objective To explore the value of phase-contrast magnetic resonance imaging (PC-MR) in diagnosis of secundum atrial septal defect (ASD) in pediatric patients. Methods Totally 42 patients (aged from 9 months to 15 years) with secundum ASD proved with tansthoric echocardiographic (TTE) were evaluated with PC-MRI. Images of the flow through ASD were obtained with PC-MRI. The distances of ASD rim to superior vena cava (SVC), inferior vena cava (IVC), atrioventricular valves (AVV) and right upper pulmonary vein (RUPV), as well as the entrances of the vena cava and right upper pulmonary vein (RUPV) were assessed. Results The sizes of ASD and distances of ASD rim to the adjacent structures (SVC, RVC, AVV and RUPV) at PC-MRI were well consistent with those of TTE in 42 patients (P<0.001). PC-MRI results in 26 patients correlated well with surgical results (P<0.001). With different velocity encoding, compared with surgical results, measurements of ASD's sizes were more accurate when setting velocity from 50 to 70 cm/s than 90 cm/s. Conclusion The shape of ASD can be virtually depicted with PC-MRI. PC-MRI can accurately assess the defect size, number, rim distances to adjacent structures, therefore providing a new method for depiction of congenital heart anomaly.

Objective To report 115 cases of congenital aortic arch anomalies, and to evaluate the imaging diagnostic techniques. Methods One hundred and fifteen patients with congenital aortic arch anomalies underwent angiocardiography and(or)contrast enhancement magnetic resonance angiography (CE MRA). Results In this 115 cases, double aortic arch was seen in 5 cases, right aortic arch with aberrant left subclavian artery in 45 with isolated left subclavian artery in 11, left aortic arch with aberrant right subclavian artery in 33, right aortic arch with left descending aorta in 7, left aortic arch with right descending aorta in 4, cervical aorta in 4, and others in 6. Conclusion CE MRA is a reliable noninvasive imaging diagnostic method.