Optical coherence tomography angiography (OCTA) is a new and non-invasive imaging technique that is able to detect blood flow signal in the retina and the choroid within seconds. OCTA is different from the traditional angiography methods. The major advantages of OCTA are that it can observe blood flow signal in different layers of the retina and the choroid without injecting any dye, provide blood flow information that traditional angiography cannot provide, and enrich pathophysiological knowledge of the retinal and choroidal vascular diseases., which help us to make an accurate diagnosis and efficient evaluation of these diseases. However there is a large upgrade potential either on OCTA technique itself or on clinical application of OCTA. We need to fully understand the advantage and disadvantage, and differences of OCTA and traditional angiography. We also need to know how to interpret the result of OCTA. With that we could make a fast diagnosis in a non-invasive way and improve our knowledge of the retinal and choroidal vascular diseases.
As a new and non-invasive imaging technology, optical coherence tomography angiography (OCTA) has been using in ocular fundus diseases, glaucoma and neuro-ophthalmic disorders for more than 4 years. The most valuable and efficient application of OCTA is in detecting neovascular diseases in the macula. The big advantage of OCTA is for diagnosing all kinds of choroidal neovascularization. OCTA can observe blood flow information in different layers of the retina. To a large extent, it changes our diagnostic thinking and pathway in macular diseases. Before acquiring OCTA image, the operator should be well trained to ensure to get high quality images with good signal strength and less artifact. OCTA report should show the segmentation slab that the ophthalmologist wants to see. So far, OCTA has difficulty to reach peripheral retina with default setting. Even so, OCTA has provided much information of blood flow within retinal vascular arcade for evaluating structural and functional changes. We are expecting that the swept source OCTA could give us better observation of the choroidal blood flow. That should be the breakthrough of the new generation of OCTA.
OBJECTIVE: To review the role of thyroid hormone in the peripheral nerve regeneration. METHODS: The recent literatures of experimental study and clinical application on the role of thyroid hormone in nerve regeneration were reviewed. The researches on expression, isoform and changes of thyroid hormones in rat sciatic nerve in normal or injury were summarized. The effect of thyroid hormone on local rat sciatic nerve was studied, too. RESULTS: Nuclear thyroid hormone receptors expressed in numerous nuclei of sciatic nerve during a limited period of development extending from the third week of embryonic life to the end of the second postnatal week and after injury of adult sciatic nerve. A single and local administration of thyroid hormone at the level of the transected sciatic nerve produced a lasting effect on peripheral nerve regeneration. CONCLUSION: The beneficial effects of thyroid hormones upon injured peripheral nerve may have considerable therapeutic potential.
Objective To summarize ultrasonography, CT and (or) MRI imaging features of cystic liver lesions so as to improve its diagnostic accuracy. Methods The literatures relevant imaging studies of different types of cystic liver lesions at home and abroad were searched. Then with the etiology as clue, the imaging fetures of ultrasonography, CT and (or) MRI plain scan and enhancement scan were summarized. Results The cystic liver lesions had many types, their imaging findings were different and existed overlaps. The diagnosis and differential diagnosis of atypical cases were difficult. ① For the simple hepatic cyst, it was a round cystic mass with water-like echo, density and signal. The boundary was clear, and there was no separation in the cyst, without contrast enhancement. The sensitivity and specificity of diagnosing were higher by ultrasonography and MRI as compared with CT. ② For the bile duct hamartoma and Caroli diease, they were manifested as multiple cysts, widely distributed in the whole liver, without enhancement for the most lesions. The multiple cystic lesions without communicating with the bile duct was the key sign of differential diagnosis for these two dieases. ③ Enhancing mural nodules were more common in cystadenocarcinoma than cystadenoma. The accurate diagnosis of biliary cystadenoma depended on combination of ultrasonography, CT, and MRI findings. ④ For the cystic liver metastatic tumor, it was multiple cystic neoplasms in the liver parenchyma or around the liver. CT was the main method for the diagnosis, and which showed that the density was lower than that of the liver parenchyma, peripheral ring-enhanced lesion as enhanced scan. It was easy to distinguish with simple hepatic cyst by MRI. ⑤ For the cystic hepatocellular carcinoma, it presented as a multilocular cystic solid tumor. The presence of tumor thrombus in portal vein could help to the diagnosis. ⑥ For the undifferentiated embryonal sarcoma, CT plain scan showed the cystic low density mass with clear boundary, the edge with calcification, enhanced scan showed that the soft tissue composition presented continuous strengthening sign. There was no specific signal in MRI plain scan, and the periphery of the tumor was slowly strengthening. ⑦ For the liver abscess, it was easy to diagnose because it had different characteristic features in different pathological phase, but it was misdiagnosis of intrahepatic cholangiocarcinoma when its symptoms were atypical. ⑧ The ultrasonography and the CT were the optimal methods for the hepatic cystic echinococcosis and the hepatic alveolar echinococcosis respectively. The significances of imaging were to determine the activity of hydatid cyst and to identify anatomy structure among alveolar echinococcosis, bile duct and blood vessel, and judge invasion or not, MRCP was important for diagnosis. Conclusions Abdominal ultrasonography could be used as the first choice for diagnosis of cystic liver lesions, CT and MRI could be used as effective supplementary methods for it. A combination of various imaging techniques is key to diagnosis. Moreover, number and morphology of lesion, and solid component or not are important imaging features of diagnosis and differential diagnosis of cystic liver lesion.