ABSTRACT
Objective The study was to investigate the feasibility of using an intravascular Loopless Monopole Antenna (ILMA) for 3.0 T MR imaging of water bath and deep-seated arterial walls of experimental animal.Methods A novel intravascular loopless monopole antenna (ILMA) was developed,including a non-shield loach guide-wire and a matching circuit.The non-shield loach guide-wire is used as a receive antenna,with the diameter of 0.019 in( 1 in =2.54 cm) and length of 23.11 in.During the MR scanning,the ILMA was used as a receive-only probe,while body coil was used to transmit the RF pulses.Utilizing the coil in water bath and in-vivo animal experiment,we measured signal-to-noise ratio (SNR) and contrast-to-noise ratio(CNR) of artery wall using the same scanning parameter compared with phased-array coil.Results In the study,the developed novel ILMA conduced to improved SNR of imaging and much higher space resolution( 313 μm).First,the feasibility of acquiring the wall images was demonstrated on phantoms.The SNRs map generated by the matlab software showed that in comparison with the phased-array coil,ILMA generated higher SNR of the phantom wall when using the same sequences,parameters,and slices (86.8 ±0.8 vs.9.9 ±0.1,P ＜0.01 ).When imaging the aorta wall with the ILMA and phased-array coil,the SNRs of the arterial wall with the ILMA is 60.4 ±20.9,61.3 ±22.5,59.8 ±20.4,32.3 ±22.6 (T1WI),51.2 ±21.6,49.8 ± 15.5,50.4 ± 17.2,22.4 ± 18.3 (T2WI),the CNRs of the aorta wall with theILMA is 19.8±8.1,18.9±9.2,19.6±11.8,20.7 ± 13.3(T1WI),17.7±6.4,18.6±6.9,17.2 ± 6.4,17.2 ± 6.4 ( T2 WI),compared with phased-array coil,t values SNR:6.36,3.84,3.51,6.92(T1 WI),3.47,4.89,6.35,4.21 (T2WI),CNR:3.56,3.97,-0.71,4.74 (T1WI),3.99,3.01,4.27,5.03(T2 WI,P ＜ 0.05 ),respectively.Conclusion The study demonstrates the capability of using an MR ILMA to generate 3.0 T MR in-vivo experiments,the developed novel ILMA conduces to increased SNR compared with the conventional phased-array coil.
ABSTRACT
Objective:To investigate bioactivity,biodegradation,bone conductive properties,and clinical maneuverability of a novel injectable chitosan microspheres/ calcium phosphate cement(CPC).Methods: The bone defect of ??4 mm?4 mm?6 mm was made at both thighbones of 12 rabbits,and experimental material(chitosan microspheres/CPC) or control material(?-tricalcium phosphate cement,?-TCP) was injected into the defect respectively.The filling situation was evaluated by X-ray 3 days after operation.The rabbits were divided into three groups,four for each group.The samples with chitosan microspheres and the control with ?-TCP were collected at 8,16,24 weeks after operation.Histological examination and scanning electron microscope(SEM) evaluation were performed.Results: The absorption of implants with chitosan microspheres was observed at 8 weeks,and became more apparent at 16 weeks.Different size of cavities were observed in CPC after the degradation of chitosan microspheres.The chitosan microspheres/CPC was dramatically degradated after 24 weeks with a few chitosan microspheres,and new bone replaced the degradated materials.The implants with ?-TCP were absorbed slowly compared with the chitosan microspheres/CPC.The cavities in ?-TCP were small.Conclusion: The chitosan microspheres/calcium phosphate cement has the characters of good biocomptable and osteocombinative ability.Compared with the control material,adding chitosan microspheres into CPC could enhance its degradability and facilitate the new bone formation.