Phase-contrast magnetic resonance imaging (PC-MRI) is a valuable and noninvasive method for evaluating hemodynamics and assessing the severity of disease processes involving the cardiovascular system. The basical principles, influential factors and the applications of PC-MRI in the assessment of cardiovascular diseases were reviewed in this paper.

Objective To study the feasibility of cerebral perfusion weighted imaging(PWI)using superparamagnetic iron oxide particles(SPIO)Resovist in normal rabbits,and investigate the methodology and the proper contrast agent dose of SPIO in PWI.Methods All 30 rabbits were randomly divide into 5 groups(n=6 for each),group A,B,C,D were divided according to the different dose of Resovist(4,8,16 and 32 μmol Fe/kg)and group E was operated as control study with 0.2 mmol/kg Gd-DTPA.The dynamic MR perfusion imaging series were acquired in each group.The signal intensity time curves were analyzed in gray matter and white matter,and the parameters(rCBV,SRRmax,QrCBV,QSRR max)were calculated and compared in all groups and correlated with control one.Results a bolus injection was succeed for all studies.and a dose-dependent strong reduction in signal intensity of gray and white matter in all groups was demonstrated.The rCBV values of gray and white matter for group A,B,C,D and E were(50.48±3.84),(25.57±2.10);(94.69±2.60),(45.33±3.14);(141.13±6.26),(67.67±4.65);(243.75±5.90),(162.06±5.14);and(84.60±3.60),(41.36±2.18)ml/100 g,respectively.The SRRmax values of gray and white matter for group A,B,C,D and E were(13.70±1.50)%,(7.38±0.41)%;(31.01±4.06)%,(16.49±2.35)%;(43.81±3.42)%,(21.64±4.14)%;(64.49±5.35)%,(43.61±5.78)%;and(27.78±2.98)%,(14.42±2.25)%;respectively.The QrCBV values for group A,B,C,D and E were 1.98±0.07,2.09±0.11,2.09±0.07,1.50±0.01,and 2.05±0.03,respectively,and the QSRR max values for group A,B,C,D and E were 1.85±0.11,1.88±0.06,2.06±0.25,1.49±0.09,and 1.94±0.12,respectively.All above values among group were significantly different(P＜0.01).For the QrCBV and QSRR max values between group,there were no significant difference between group A and B,B and C,A and C;while the values of group A was significantly larger than those of group D(P＜0.01).Condusion Resovist(SPIO)can be used in the study of MR perfusion weighted imaging in the brain,and the proper contrast agent dose is 4-16 μmol Fe/kg.

Objective　To study the clinical application of MRI in neonatal asphyxia.Methods　There were twenty-two cases of full term infants(≤one year old),they all had asphyxia during delivery.Transverse section on TSE T2-weighted,TSE T1-weighted and FLAIR sequences,and sagittal section on TSE T2-weighted were obtained on MRI.Results　The abnormal signal intensity in white matter on MRI were found in 15 cases.The volume of white matter was decreased in three cases.Subarachnoid spaces of frontal and temporal lobe were enlarged in two cases.Two cases were normal on MRI.Conclusion　We believed that the changes of the white matter of brain in neonatal asphyxia can be showed on MRI,it is of important significance for clinical diagnosis and treatment.

PurposeTo prospectively investigate the effect of gadolinium contrast media on the quality of intravoxel incoherent motion (IVIM) MRI images and the quantification of corresponding parameters for abdominal solid organs, and to explore the appropriate time for abdominal IVIM scan.Materials and MethodsTwenty patients underwent the same abdominal IVIM scan before and after gadolinium contrast administration. The signal-to-noise ratio (SNR) of liver, spleen, pancreas and kidneys were measured on diffusion-weighted imaging (DWI) images at b=50 s/mm2, 300 s/mm2 and 800 s/mm2. SNR and contrast-to-noise ratio (CNR) of hepatocellular carcinoma (HCC) (n=16) were also calculated. Apparent diffusion coefficient (ADC) value and IVIM parameters including pure diffusion coefficient (D), pseudo-diffusion coefficient (D*) and perfusion fraction (f) of liver, spleen, kidneys parenchyma and HCC were measured and compared. ResultsSNR of liver on post-contrast DWI at b=50 s/mm2 were significantly lower than that of pre-contrast (t=2.397,P<0.05). CNR of HCC increased significantly on b=300 s/mm2 DWI images after contrast (t=-3.380,P<0.01). SNR of kidneys on DWI of any b value decreased after contrast administration (Z=-2.675--2.201,P<0.05). SNR of spleen, pancreas and HCC were not statistically different between pre-contrast and post-contrast images (t orZ=-1.324-1.104,P>0.05). As for IVIM parameters, only ADC and D values of kidneys demonstrated a significant reduction after contrast (ADC:t=3.569,P<0.01; D:Z=-3.053,P<0.01). No significant differences were detected for all parameters of liver, spleen and HCC between pre-contrast and post-contrast images (t=-1.102-1.689,P>0.05). ConclusionAdministration of gadolinium contrast media may result in decrease of SNR of liver on low b value DWI and SNR of kidneys at any b value, but it increases CNR of hepatic lesions on medium b value DWI. Administration of gadolinium contrast media does not make a significant effect on SNR of spleen, pancreas and hepatic lesions. Furthermore, ADC and D values of kidneys decrease after administration of gadolinium contrast media. There is no significant influence of contrast medium on DWI and IVIM parameters of liver, hepatic lesions and spleen.

Objective To evaluate the features and visualization of venous arcades of the pancreatic head (VAPH) using 16-slice CT with different techniques.Methods Portal-phase CT scanning with 16-slice CT was performed in 40 cases.The visualized rate of VAPH with axial images,thin slice maximum intensity projection(TSMIP) and volume rendering(VR) was assessed.Results With axial images,TSMIP and VR,the visualized rate of right gastro-epiploic vein and gastro-colic vein were all 100% and 80% respectively;while for right colic superior vein was 100%,87.5% and 80%;pancreaticoduodenal posterior-superior vein was 92.5%,65% and 40%;pancreaticoduodenal anterior-superior vein was 92.5%,62.5% and 45% respectively.Conclusion VAPH can be showed definitely using 16-slice CT in combination of axial images,TSMIP and VR images.

As inhibitors of osteoclasts, Bisphosphonates are a group of drugs used in the treatment of oncology patients with bone metastases. However, some reports have described osteonecrosis of the jaws occurring after taking drugs containing bisphosphonates. The advances in clinical manifestation, imaging findings as well as the mechanisms of bisphosphonate-associated osteonecrosis of the jaws were reviewed in this article.

Objective To investigate the CT and MRI features of desmoid-type fibromatoses(DF).Methods The images of 29 ca-ses with DF proved by pathology were reviewed retrospectively.CT and MRI examinations were performed in 1 5 cases respectively, and both in 1 case.Results The median age was 33.0 years with a male-to-female sex ratio of 1 ︰ 2.2.36 lesions were discovered,among which 26 cases were solitary while 3 cases had multiple focus.1 9 lesions were extra-abdominal,14 ones in the abdominal wall and 3 ones intra-abdominal.The largest diameter of tumors was 13 -1 75 mm.27 lesions displayed ovoid or elongated shape while 9 ones were irregular .The boundary could be clear or unclear.25 lesions extended along muscle planes with consistent long axis.23 focuses grew aggressively,1 6 of which crossed the muscle clearance,while 13 lesions grew expansively.On CT,20 lesions appeared iso-den-sity or slightly hypo-density compared with normal muscles,mostly homogeneous(1 5/20).Most lesions exhibited gadually moderate or obvious enhancement on post-contrast CT,and the enhancement was homogeneous or heterogeneous.1 7 lesions were found on MRI,which presented signal intensity similar to or slightly higher than that of muscles on T1 WI and most were homogeneous(12/1 7);on T2 WI,all were heterogenous with slightly high or high intensity.All lesions demonstrated obvious enhancement on MRI after contrast administration ,and most were heterogeneous(12/1 7).Sheets or bands of low signal were detected within 1 1 lesions with no enhancement.Conclusion DF has some characteristics on CT and MRI,which are valuable for accurate pre-operative diagnosis,and for evaluation of the lesion extent and involvement of adjacent structures.

Objective To assess the feasibility of ~(18)F-FDG PET/CT for differentiation of malignancy from benign in pericardial Lesions. Methods ~(18)F-FDG PET/CT data of 16 patients with pericardial lesions (9 malignancy, 7 benign) were analyzed using maximum standard uptake values (SUV_(max)) and the density of lesions, the relationship with surrounding tissues were also evaluated. The results of malignancy or benign were proved by needle biopsy.Results SUV_(max) of malignancy (10.1±6.0) and benign (3.0±2.1) was significant different (P<0.01). Taking the optimal cut-off value as SUV_(max) 3.5-4.5, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of differentiation of malignant from benign in pericardial lesions was 100%, 85.71%, 93.75%, 90.00% and 100%, respectively. Conclusion ~(18)F-FDG PET/CT can predict benign or malignance of pericardial lesions with moderate accuracy.

Objective To evaluate the value of Feridex in demonstrating small focal lesions of the liver on MRI and to discuss the optimal scan time after intravenous administration of Feridex. Methods Small focal lesions in the liver were found on ultrasound or CT in 17 patients. Conventional MR plain scan and Gd-DTPA enhanced scan were performed. One to three days later, T 2 weighted imaging was repeated at 0.5 h, 3 h, and 6 h after Feridex was administered intravenously over 30-40 min at a dose of 0.05 ml/kg. The pre- and post-contrast T 2WI were compared and analyzed in terms of lesion detectability and signal change. Results Twenty-one lesions with diameter smaller than 1 cm were found on the Feridex enhanced images, and only 8 lesions were found on the conventional MR images. The small hepatic cancers, focal nodular hyperplasia (FNH), and regenerated nodules had different signal changes on the Feridex images, which made the differential diagnoses easier. The signal of the liver decreased significantly (P0.05). Conclusion Fridex enhanced MR images could not only improve the detection of small focal lesions, but also provide evidence for differential diagnoses.

Objective To investigate the value of perfusion MR imaging in differential diagnosis between primary central nervous system lymphomas(PCNSL)and high grade astrocytomas.Methods Twelve patients with PCNSL and 23 patients with high grade astrocytomas were preoperatively examined using a 1.5T MR unit.Routine MR sequences were performed followed by dynamic susceptibility contrastenhanced MR perfusion imaging.The perfusion color images and the time-signal intensity curves of the two tumor groups were compared.The relative cerebral blood volume(rCBV)within the tumor parenchyma was measured and the data were analyzed with unpaired Student's t-test.Results The rCBVs within the tumor parenchyma of the PCNSL and high grade astrocytomas were 1.78±0.5 1 and 3.87±0.87 respectively.The rCBV in the PCNSL was significantly lower than that of the high grade astrocytoma(P＜0.05).When the time-signal intensity curves were compared,the PCNSL showed a trend towards the baseline after the first pass and the curves even overshot above the baseline in 7 out of 12 cases,whereas the high grade astrocytoma showed a trend to be close to the baseline but couldn't return to the baseline completely.Conclusion The MR perfusion imaging can be very useful in distinguishing the PCNSL from high grade astrocytomas.