Objective To evaluate the characteristics of CT, MRI, PET and histopathology of brain radiation injuries following radiotherapy for nasopharyngeal carcinoma. Methods We reviewed the imaging records of 71 patients with brain radiation injuries following radiotherapy for nasopharyngeal carcinoma examined over a 10 year period. Results The radiation injury lesions occurred in the temporal lobes, brain stems or cerebella. Their CT appears were homogeneous or heterogeneous density. If the lesions situated in temporal lobes, they presented as "finger like" hypointensity. Twenty three patients(29 lesions) undenwent contrast enhanced CT scan, 86.2 percent(25/29)of the lesions showed no enhancement. MRI demonstrated prolonged T 1 and T 2 relaxation time of the injured tissue, they might showed homogeneous or heterogeneous signal intensity. MR enhanced T 1WI were performed in 20 cases(29 lesions),and 65.5 percent(19/29)of the lesions presented "Flower lace" enhancement. Two patients were carried on PET scan. One patient′s PET appearance is similar to the CT or MRI finding. Resections and histopathologic observations of temporal lobes′ lesions were performed on 3 cases, which showed cerebral necrosis. Conclusion (1) MRI plain or contrast enhanced scan is more sensitive than that of CT or PET. (2)The heterogeneous signal intensity on T 1WI and T 2WI represent necrosis,and all are located in the radiation field. (3)"Flower lace" enhancement on contrast MRI is the characteristic of brain radionecrosis. (4)PET may serve as a complementarity in the diagnosis of radiation induced injuries.

Objective To explore the susceptibility weighted imaging (SWI) appearance of paramagnetic and diamagnetic materials, its imaging theory, and its value of differential diagnosis from their appearance. Methods The diamagnetic and paramagnetic phantom were made and the X-Y axial SWI phase image of phantom then was obtained. Twenty-eight cases of intracerebral calcium and 21 cases of hemorrhage examined with MRI scan and CT scan were retrospectively investigated. The appearance of calcium and hemorrhage on SWI were analyzed and compared with their appearance on CT and conventional MRI. Results Phantom experiment indicated that the equator plane scan of diamagnetic sphere showed high signal in centre surrounded by low signal ring and high signal in two poles of sphere along Z axis of main magnetic field. The paramagnetic sphere appeared the opposite appearance of diamagnetic sphere with centre low signal surrounded by high signal ring in equator plane and low signal in two poles of sphere along Z axis of main magnetic field. The SWI manifestations of 4 cases of intracerebral sphere or sphere-like calcification ( chorioidal calcification) and 9 cases of sphere or sphere-like hemorrhage(2 cases of traumatic hemorrhage, 1 case of hypertension related basal ganglion hemorrhage, 4 cases of metastasis hemorrhage and 2 cases of cavernous hemangioma hemorrhage)were consistent with diamagnetic and paramagnetic sphere phantom respectively. Four cases of calcification in basal ganglion showed the mixed high and low signal. Seven cases of irregular calcification ( neoplastic calcification) aside from basal ganglion appeared complex appearance, though mainly in high signal. Other sphere or sphere-like calcification aside from basal ganglion ( 14 cases of pineal calcification, 4 cases of chorioidal calcification, 2 cases of cerebral cysticercosis calcification and 1 case of neoplastic calcification ) showed markedly high signal. Nine cases of intracerebral iobular hemorrhage (2 cases of hypertension related basal ganglion hemorrhage, 4 cases of unknown casual hemmorrhge and 3 cases of cavernous hemangioma hemorrhage) displayed a multiple concentric circle appearance, other 3 hemorrhage showed complex appearance, though mainly in low signal. Ten cases of calcification had no specific appearance on T1 WI and T2WI. Conclusion Phase image of SWI is helpful in differentiating intracerebral diamagnetic from paramagnetic materials and it has some advantage in detecting calcification over T WI and T2 WI.

Purpose to explore a CT classflication of hepatic echinococcal cysts and its clinical application. Materials and Methods reviewed 85 patients who had underwent CT scan in our hospital from 2008-01～2009-12.The CT classification was made according to WHO classification and the CT appearances were analyzed retrospectively.Results Among the lesions,there were 16 CL type,appeared as a unilocular round cyst without wall.15 CE1 type,appeared as a unilocular cyst with a smooth uniform wall.28 CE2 type,appeared as a fluid collection with septa (honeycomb sign),and 6 CE3 type,CT appeared as a fluid collection with a split wall,10 CE4 type,CT appeared as a fluid collection with a split wall (water-lily sign).36 CE5 type,CT appeared as a calcified mass.Conclusion CT classification according to WHO classification for cystic echinococcosis is using to differentiate it from other liver cystic lesions,such as simple cyst and abcess,and is essential when planning clinical treatment.

Objective To investigate MRI features of dysembryoplastic neuroepithelial tumor(DNT).Methods The MR images of ten cases with surgically and pathologically proved DNT were retrospectively reviewed.Results MR imaging showed cystic component with mural nodule in 6,mainly cystic component with septa in 3.The solid components of the tumors were long T_1 and long T_2 signal intensity,the cystic components were even longer T_1 and T_2 signal intensity which resembled the signal of cerebrospinal fluid.Mild enhancement could be found at the intra-tumoral solid nodule or septations after injection of constrast medium but the cystic component did not show any enhancement.No peri-tumoral edema and mass effect were found in most cases.Conclusion DNTs are of some special features on the MR images,the diagnosis can be exactly done before operation if MRI features in combination with clinical data of the patients.

Objective To study CT and MRI value in diagnosis of osteoblastoma,in order to achive more information about the disease. Methods The clinical,CT,MRI and histological data of 12 patients with osteoblastomas. Results(1)There were 6 patients wereexamined by CT,the lesions showed mainly lytic with varying degrees of matrix mineralisation,and mild adjacent reactive sclerosis;(2)10 patients were examined by MRI(included 4 patients who have been examined by CT),the lesions presented mixed signal intensity with compart,slightly low and intermediate signal intensity on T_1-weighted images,high signal intensity on T_2-weighted images were found in 9 cases and mainly low signal intensity was found in 1 case.8 cases showed clear low signal intensity surrounding the lension borh on T_1 and T_2,2 cases showed blurry high signal in the adjacent tissue;(3) The tumors presented moderate enhancemen with low dense area inside the lesions after injection of contrast media. Conclusion Osteoblastomas have classical features on CT,while show no characteristic appearances on MRI.

Objective To explore the imaging features and pathological characteristics of fibrous dysplasia of craniofacial bone. Methods 42 cases with fibrous dysplasia of craniofacial bone confirmed surgically and pathologically were retrospectively analyzed. Results There were 35 cases with single bone involved and 7 cases with poly-bone involved. On CT images, the lesions appeared as glass-like change(79.3%). The main pathological components of the lesion were fiber and fiber-like tissue, which were low signals on both T_1 WI and T_2 WI, and the signal intensity was changed with the accompanied by hemorrhage, necrosis or cystic degeneration. Conclusion CT and MRI are the effective imaging modality in diagnosis of fibrous dysplasia of craniofacial bone.

Objective To summarize MR manifestations of cerebral arteriovenous malformations (AVMs), and to evaluate the accuracy of MR angiography in determining cerebral AVMs’ aspects. Methods Thirty-six cases of cerebral AVMs were analyzed comparatively between MRA and DSA in sizes, feeding arteries and draining veins. Results Cerebral AVMs were appeared in every part of brain. MRI showed honeycombed and linear flow-void low intensity signal in lesion area, showed flow-void signal of expanded thickening vessels, and showed cerebral atrophy or fraction surrounding the lesions. MRA showed that the sizes of most AVMs were 2～5 cm, that the feeding arteries originate from the expansion of original feeding arteries of these areas, that the draining veins drain from the lesions into the surrounding veins or sinuses. The numbers of these vessels were related positively to the sizes of lesions. The differences in showing AVMs between MRA and DSA were that the sizes of lesions on MRA were more than those on DSA, and the numbers of draining veins on MRA were more than those on DSA. Conclusion MRA may show all signs of AVMs, and is not less than, or superior to DSA in their diagnosis. MRI may play important roles in the examination and the diagnosis of cerebral AVMs.

BACKGROUND: Sonography is believed by many scholars to be sensitive for the detection of hepatic arterial thrombosis and stenosis, but it is difficult to show the anastomotic vascular stenosis. MR angiography is better than sonography in the display of vascular anatomy and the diagnosis of various vascular complications after liver transplantation.OBJECTIVE: To evaluate the role of MR angiography (MRA) in the display of vascular anatomy and the diagnosis of various vascular complications after liver transplantation.DESIGN: Contrast trial observation.SETTING: Medical Imaging Center of Nanfang Hospital, Southern Medical University.PARTICIPANTS: Eleven adult male patients had undergone liver transplantations at Nanfang Hospital of Southern Medical University between January 2004 and December 2006. They ranged in age from 40 to 58 years, average 49 yeas. Original causes of liver failure in the study group included cirrhosis (n =9) and primal hepatic carcinoma (n =2) diagnosed by pathohistological methods. And 9 cases had undergone orthotopic liver transplantations while 2 cases with piggy-back liver transplantation.METHODS: Eleven consecutive adult patients underwent MR imaging examinations after orthotopic liver transplantation using a breath-hold 2D True Fast Imaging with Stead-state Precession and Fast Low Angle Shot. MR triphasic contrast-enhanced 3D imaging was also performed. Enhancement scan: A final gadolinium-enhanced axial and coronal T1WI spin-echo sequence with spectral fat saturation was performed after completion of the MRA. The vascular diameter stenosis was calculated according to S (S=[(D-d)/D]×100%) by ECST method, d as the inner diameter of the most obvious stenosis while D as normal diameter. Degree of stenosis: normal as S 0-30%, mild stenosis as S 31%-50%, moderate stenosis as S 51%-85%, and severe stenosis as S 86%-100%. Then the imaging findings after liver transplantation were analyzed. Meanwhile the sonography was performed.MAIN OUTCOME MEASURES: ① MR Image analysis of vascular anatomy and vascular complications after liver transplantation.②Normal findings after liver transplantation by using sonography.RESULTS: All 11 patients were involved in the result analysis.①MRA: The anastomosis of hepatic artery, portal vein and inferior vena cava were smooth in 3 cases. The high signal intensity was seen around portal vein at T2WI in 1 case with a shorter interval after transplantation and persisted 3 weeks. In 1 case, the caliber of the donor portion was smaller than the recipient portion. Among other 8 cases, hepatic artery complication included hepatic artery winding in 2 cases and aneurysm formation of donor's hepatic artery in 2 cases, but the twig of the hepatic artery was normal. Mild Portal vein stenosis at the anastomosis was found in 2 cases, caused by the different calibers of the donor portion from the recipient portion, but the inter-hepatic branches of the portal vein were normal. Clubbed dilatation of hepatic veins end-brush was depicted in 2 cases whose inferior vena cava at the anastomosis was not stenosis. Inferior vena cava thrombosis was found in 1 case. The thrombus displayed the low signal intensity in the high signal intensity of inferior vena cava. By follow-up examination, the degree of clubbed dilatation of hepatic veins end-brush reduced after half a year and inferior vena cava thrombosis disappeared by treatment. ②Sonography: By ultrasound examination, 1 case who had hepatic artery winding combining to aneurysm formation of donor's hepatic artery was discovered just hepatic artery winding. In 2cases that had mild portal vein stenosis at the anastomosis, 1 case was diagnosed normal while the other was not affirmed. The clubbed dilatation of hepatic veins end-brush was not depicted. The others were same as MRI diagnosis.CONCLUSION: Dynamic enhanced 3D MRA imaging can provide a comprehensive assessment of vascular anatomy in most recipients of liver transplants, and is an accurate and quick method to diagnose the vascular complication after liver transplantation.

Objective To investigate the role of MRI in diagnosis of primary intracranial teratoma.Methods Nine cases of primary intracranial teratoma proved by operation and pathology were examined by MRI before operation.MRI features were analysed retrospectively.Results The localized and qualitative rates were 100% and 88.8% respectively.The characteristic MRI appearances of primary intracranial teratoma were as follows:(1)The tumor was lobular in shape with clear margin;(2)The tumor had heterogeneous signal intensity ;(3)Inhomogeneous Gd-DTPA enhancement in most of the tumors.Conclusion Multiplanar imaging and Gd-DTPA enhancement in MRI are helpful in diagnosis and differential diagnosis of teratoma.

Objective To investigate the role of CT and MRI in diagnosis of the pineal region germinoma.Methods 11 cases of the pineal region germinoma proved by operation and pathology. CT and MRI features were analysed retrospectively. Results In 11 cases on CT most tumors were hyperattenuation or isoattenuation. Enhancement in most of the tumors were homogeneous. The characteristic MRI appearances of the pineal region germinoma were as follows: (1) On T 1WI, the lesions were isointense or slightly hypointense while isointense or slightly hyperintense on T 2WI. The pineal region germinoma showed no edema. (2) The lesions showed homogeneous or inhomogeneous Gd-DTPA enhancement in most of the tumors.Conclusion CT and MRI of multiplanar imaging and Gd-DTPA enhancement are helpful in diagnosis and differential diagnosis of pineal region germinoma. The tumors have sex, location and imaging characteristics.