BACKGROUND: An effective method to enhance the accuracy and sensitivity of magnetic resonance imaging (MRI) is to select a targeted contrast agent. OBJECTIVE: To prepare gadopentetic acid -polybutylcyanoacrylate nanoparticle (Gd-PBCA-NP) and to investigate its liver-targeted values in animal experiments.DESIGN, TIME AND SETTING: A comparative observation was performed at the Laboratory of Department of RadiologicelCenter, Nanfang Hospital between September 2004 and January 2005. MATERIALS: Gd-PBCA-NPs were prepared by anionic emulsion polymerization. METHODS: A total of 18 Wistar rats were randomly divided into 3 groups, with 6 rats per group: Gd-DTPA, PBCA-NP, and Gd-PBCA-NP. Following caudal venepuncture (catheter remained), rats received 0.1 mmol/kg Gd-DTPA, 10 mL/kg PBCA-NP, or 10 mL/kg Gd-PBCA-NP. MRI scans (coronal and transverse) were performed prior to and after different enhancement protocols using a head coil for transmission and reception of the signal. Immediately after contrast medium injection, dynamic data of each group were acquired at 5, 15, 30, 60, and 120 minutes using imaging parameters the same as for the pre-contrast images. MAIN OUTCOME MEASURES: The morphology of Gd-PBCA-NPs was observed using transmission electron microscope. The size and the index of size distribution were measured through the use of laser granulometer (Malvern-3000HS). The Gd ion concentration in the dialysate was determined by inductively coupled plasma atomic emission spectroscopy for calculation ofencapsulation efficiency and loading capacity of Gd-PBCA-NP. The enhanced rate of the liver at each time point was calculated. RESULTS: The morphology of Gd-PBCA-NPs was spherical shape with core-shell structure and without adherence between particles. The average size of Gd-PBCA-NPs was 65.7 nm, and the index of size distribution was 0.09 measured by dynamic light scattering. The average encapsulation efficiency and loading capacity of Gd-PBCA-NPs were 81.97% and 51.23%, respectively. After intravenous injection of Gd-DTPA, the enhanced rate of the liver was 35.2% and 48.6% at 5 and 15 minutes respectively and the kidney was obviously enhanced; at 30 minutes, the enhancement of the liver recovered to normal level. After intravenous injection of Gd-PBCA-NPs, the average enhanced rate of the liver was 3.4%, 22.7%, 36.1%, 56.4%, and 24.8% at 5, 15, 30, 60, and 120 minutes accordingly. After intravenous injection of PBCA-NP, the enhancement of the liver was not found. CONCLUSION: Gd-PBCA-NPs can be taken as liver-targeted MRI contrast agents and have potential application value in MRI.

Objective To study the CT characteristics of inflammatory pseudotumor of the liver(IPL).Methods 16-slice spiral CT findings of IPL in 16 cases were analysed retrospectively.The CT values of IPLs and the liver tissue surrounding the lesions were measured on plain and contrast-enhanced CT scans.Results Totally 18 lesions in 16 cases were detected by CT,most of them(16 lesions) located in the right lobes of liver.The lesions appeared as low-density,round or round-like,or irregularity in sharp.Dynamic enhanced CT scan showed the lesions no or slight enhancement in arterial phase,slight to moderate enhancement in portal vein phase.A part of the lesions showed ring enhancement surrounding the lesions,nodular or fiber stripped enhancement in the center of lesions,and the branches of the portal vein passesed through the lesions.In enhanced degree of the lesions,there was not statistical difference in arterial phase compared with plain CT scans,but there were statistical differences in portal-venous phase compared with plain scan and arterial phase.In the liver around the lesion,the enhanced degree had statistical difference in artery phase and portal-vein phase compared with plain CT scans.Conclusion Dynamic enhanced CT scan shows that IPL is of hypovascularity,it's of characteristic in the portal-venous phase and delayed phase.

Objective To assess the value of CT in the detection of spontaneous rupture of hepatocarcinoma as well as to assess CT finging of hepatocarcinoma rupture.Methods Clinical manifestation and CT findings of spontaneous rupture of hepatocarcinoma in 22 cases proved surgically and pathologically were reviewed. CT characters of variable pathological changes of ruptured hepatocarcinoma and its relationship to the rupture of hepatocarcinoma were also analyzed. The analysis involved the status of liver cirrhosis, ascites, intrahepatic locations of the tumor, extent of extrahepatic protrusion and central necrosis of the tumor.Results All ruptured tumours were located at the periphery of the liver, 12 cases had a protruding contour. The maximum diameter of tumours ranged from 2 to 16 cm. Discontinuity of the hepatic surface was seen in 16 cases,necrosis of core was seen in 12 cases. 3 cases with non-ruptured masses also showed contrast medium flow over the perihepatic border during the arterial phase. 2 cases showed a haematoma with attenuated rim inside the mass, but rupture was found during surgery. 1 case show detached broken bits drifting in mass ascites. In 5 cases, CT images during the arterial phase showed a non-enhancing low attenuating lesion with focal discontinuity and peripheral rim enhancement. Conclusion The accuracy of CT diagnosis of spontaneous rupture of hepatocarcinoma is very high. Moreover, CT is a necessary imaging modality in diagnosis of ruptured hepatocarcinoma suspected by clinical findings.

Objective To investigate the value of superparamagnetic iron oxide particles(SPIO) in MR imaging for differentiation of metastatic lymph nodes from normal or reactively hyperplastic lymph nodes. Methods For the time course study,10 ?mol Fe of SPIO per extremity was administered to 6 animals, and images were obtained before and 1 h to 48 h after administration. Reactively hyperplastic lymph node model was established in 6 animals by injection of egg yolk emulsion, and tumor bearing lymph node model was established in another 6 rabbits. MR images of the popliteal lymph nodes were obtained before and 12 h after subcutaneous administration of SPIO. Imaging results were analyzed and correlated with pathological findings. Results In unenhanced images, the signal intensity of tumor free and metastatic lymph nodes did not differ significantly. After administration of SPIO, a significant signal intensity loss occurred in the tumor free lymph node, and the maximal loss occurred at 12 h, and the signal intensity reduced by 49%,28%,59%, and 89% on T 1WI, T 2WI, PDWI, and T  2WI, respectively at 48 h( P =0.000). However, the signal intensity of the metastatic lymph nodes remained unchanged. Conclusion MR imaging after subcutaneous administration of SPIO help to differentiate metastatic from normal or reactively hyperplastic lymph nodes.

Objective To analyze MRI findings of cesarean scar pregnancy (CSP). Methods The MR findings in 18 patients who were diagnosed as CSP by surgery from March 2010 to November 2011 were retrospectively analyzed,and comparison was made between the MRI findings and surgical results.Results All Gestational sacs (18) were clearly detected by MRI.Among the 18 cases,gestational sac presented as cystic mass with smooth margin located within the scar of uterine wall at the lower anterior uterus in 16 cases.In 2 of the 16 cases,gestational sac was found within the myometrium,whereas in the remaining 14 cases,gestational sac was found partially within the myometrium with extension into the uterine cavity.The anteior wall of isthmus uteri became thinner.In the remaining 2 of the 18 cases,gestational sac presented as irregular,multilobolated mass,growing deep inot the myometrium as well as into the uterinecavity. On T2WI,the mass showed heterogeneous signal intensity. A small amount of hemorrhage within the mass and uterine cavity could be seen on T1 WI. An enhancing solid component with a heterogeneous mass could be seen. All gestational sacs in 18 cases were located at or adjacent to the previous cesarean scar.In the area of cesarean scar,the signal of the uterine wall was disconnected,with focal indentation or thinning and the previous cesarean scar exhibited hypointensity on both T1WI and T2WI.Conclusion CSP has its unique findings on MRI,these specific features can provide useful information in the management of CSP.

BACKGROUND: Biliary complications are the common complication of liver transplantation. However, it is difficult to find the complications, since no obvious characteristic signs on the patients. Magnetic resonance imaging (MRI), especially,magnetic resonance cholangiopancreatography (MRCP) may provide a comprehensive evaluation of the functions and complications of the transplanted liver as a safe, noninvasive and exact technique.OBJECTIVE: To evaluate the manifestation of biliary system after liver transplantation by MRCP and its value of diagnosis of biliary complications.DESIGN: Comparative observation.SETTING: Medical Imaging Center, Nanfang Hospital, Southern Medical University.PARTICIPANTS: A total of 13 male liver transplantation patients aged from 40-58 years, who received imaging examination at Medical Imaging Center, Nanfang Hospital, Southern Medical University from January 2003 to January 2005, were enrolled. Original causes of liver failure included cirrhosis (n =11) and primal hepatic carcinoma (n =2). Ten received orthotopic liver transplantation, while 3 received piggyback orthotopic liver transplantation. Anastomotic mode of bile duct was common bile duct end-to-end anastomosis. The interval between transplantation and MRI examination ranged from 15 days to 1 year. All patients knew the items of examination and agreed to participate in the experiment.METHODS: Thirteen patients with orthotopic liver transplantation underwent turbo spin-echo (TSE) and fast low angle shot (FLASH), MRCP, Gd-DTPA enhanced MRI to analyze the characteristics of each imaging after liver transplantation.MAIN OUTCOME MEASURES: The imaging findings of the reestablished bile duct and complications of bile duct at MRCP.RESULTS: The diameters of bile duct and caliber were normal, no stricture on anastomotic stoma in 3 patients.Thick-section planes of MRCP did not develop biliary duct of one case. Biliary dilation occurred in 8 patients. There were 5 cases of biliary strictures and 2 cases of choledochus stone. Mucocele of bile duct remnant was identified in 2 cases.Bile leakage occurred in 1 case after T-tube was removed. Rejection reaction occurred in 2 cases.CONCLUSION: MRCP not only can display the image of reestablished biliary tract after liver transplantation, but also can exactly diagnose complications rapidly.

Objective To evluate Feridex-enhanced MRI in the diagnosis of focal hepatic lesions. Methods Conventional plain and Feridex-enhanced MR scanning was performed in 20 cases with suspected hepatic neoplasm.The number of lesions on T 2WI ,and the signal intensity of liver and lesions demonstrated on plain and enhanced scans were observed and analyzed.Results After the injection of Feridex,the signal intensity of normal liver tissue reduced significantly,while the signal intensity of lesions showed no marked changes,Feridex-enhanced MRI clearly displayed more lesions on T 2WI than plain scanning did.Conclusion Feridex-enhanced MRI is very sensitive in detecting focal hepatic lesions.

Objective To evaluate the dynamic imaging alteration of radiation-induced hepatic injuries after stereotactic radiotherapy (SRT) in hepatocellular carcinoma.Methods 18 healthy New Zealand white rabbits inoculated VX_2 carcinoma underwent 40 Gy SRT and divided into three groups randomly.The rabbits underwent identical plain and enhanced MR imaging after SRT 3 weeks,9 weeks and 20 weeks respectively. The signal-to-noise ratios of irradiation area and the surrounding normal liver on T_1WI and T_2WI imaging were calculated;The percentage enhancement of the hepatic injuried areas and the surrouding livers after Gd-DTPA enhanced was also calculated.Results After radiotherapy three weeks, the signal-to-noise ratios of irradiation areas on T_1WI and T_2WI were no difference between normal liver tissue and irradiation area; there were significant difference between normal liver tissues in radiotherapy nine weeks and twenty weeks; The difference in the signal-to-noise ratios of irradiation area were significant between after three weeks and nine weeks, twenty weeks. There were no difference in the signal-to-noise ratios of irradiation area between nine weeks and twenty weeks.The percentage enhancement of the hepatic injuries area have significant difference in arterial phase between three weeks and twenty weeks and between nine weeks and twenty weeks;The difference in portal and delay phase were significant between three weeks and nine weeks, twenty weeks, there were no difference between nine weeks and twenty weeks.Conclusion Dynamic enhanced and unenhanced MR imaging can reflect the pathological background of radiation-induced hepatic injuries in different phases.

0 05),but arterial oxygen tension and FEV 1 were elevated obviously (P

0.05). Conclusion DSA is highly valuable for the evaluation of collateral pathways of ICA stenosis or occlusion, and it is necessary for preoperative examination. MRA is a non-invasive angiographic method and can evaluate collateral circulation in both morphology and function, and can be the preferred method for the disease.