Application of 8-channel NV Array-A coil in neonatal head examination / 局解手术学杂志

Objective To evaluate the optimal selection of 8-channel NV Array-related coil(NV Array-A)in neonatal head MRI exam-ination.Methods A total of 84 newborn infants were divided into two groups with 42 cases in each group, and they were examined by 8-channel NV Head-A coil and NV Array-A coil respectively.The same scan parameters were used to obtain transversal T 1-weighted, T2-weighted,T2 Flair,diffusion-weighted imaging and sagittal T1 weighted imaging and other images.Compared and analyzed the image quality of the two groups,including image signal to noise ratio,uniform image signal and coil artifacts.Results In the 8-channel NV Head-A coil group,the image signal to noise ratio was 83.3%,the rate of uniform image signal was 33.3%,and the rate of clear image without coil artifacts was 81.0%.The corresponding data in the 8-channel NV Array-A coil group were 97.6%,4.8%,and 100%respectively.Examina-tion with NV Array-A coil could improve the image signal to noise ratio and reduce the rate of uniform image signal and coil artifacts.And there were statistically significant difference in the rate of uniform image signal and coil artifacts between the two groups(P<0.05).Conclu-sion The effect of NV Array-A coil scanning image in neonatal brain MRI is superior to that of NV Head-A coil,and the uniform image sig-nal and coil artifacts can be obviously reduced.NV Array-A coil is more suitable for neonatal brain MRI examination.

A Projection-based Intensity Correction Method of Phased-Array Coil Images

PURPOSE: To develop a novel approach to calculate the sensitivity profiles of the phased array coil for use in non-uniform intensity correction. MATERIALS AND METHODS: The proposed intensity correction method estimates the sensitivity profile of the coil to extract intensity variations that represent the scanned image. The sensitivity profile is estimated by fitting a non-linear curve to various angles of projections through the imaged object in order to eliminate the high-frequency image content. Filtered back projection is then used to compute the estimates of the sensitivity profile of each coil. The method was applied both to phantom and brain images from 8-channel phased-array coil and 4-channel phased-array coil, respectively. RESULTS: Intensity-corrected images from the proposed method have more uniform intensity than those from the commonly used `sum-of-squares' approach. By using the proposed correction method, the intensity variation was reduced to 6.1% from 13.1%, acquired from the `sum-of-squares'. CONCLUSION: The proposed method is more effective at correcting the intensity non-uniformity of the phased-array surface-coil images than the conventional`sum-of-squares' method.

A Projection-based Intensity Correction Method of Phased-Array Coil Images

PURPOSE: To develop a novel approach to calculate the sensitivity profiles of the phased array coil for use in non-uniform intensity correction. MATERIALS AND METHODS: The proposed intensity correction method estimates the sensitivity profile of the coil to extract intensity variations that represent the scanned image. The sensitivity profile is estimated by fitting a non-linear curve to various angles of projections through the imaged object in order to eliminate the high-frequency image content. Filtered back projection is then used to compute the estimates of the sensitivity profile of each coil. The method was applied both to phantom and brain images from 8-channel phased-array coil and 4-channel phased-array coil, respectively. RESULTS: Intensity-corrected images from the proposed method have more uniform intensity than those from the commonly used `sum-of-squares' approach. By using the proposed correction method, the intensity variation was reduced to 6.1% from 13.1%, acquired from the `sum-of-squares'. CONCLUSION: The proposed method is more effective at correcting the intensity non-uniformity of the phased-array surface-coil images than the conventional`sum-of-squares' method.

Phased array coil and parallel imaging technology of MRI / 医疗卫生装备

The parallel imaging technology of MRI is the latest technique emerging in the last few years, which is based on the phased array coil. SMASH procedure operates by simultaneously acquiring linear combination signals with different spatial sensitivities from the phased array coils to reduce the phase encoding and shorten the imaging time. SENSE procedure operates by increasing the pace when sampling is performed in k-space, which proves a speedup by reducing the number of encoding steps. When the phased array coil designed, such problems have to be taken into account as resonant frequency, impedance match, mutual impedance and et al.