Purpose: Adenosine stress CMR is commonly used to assess myocardial ischaemia. Obtaining high quality images requires maximising signal to noise ratio (SNR) over a large double-oblique field of view (FOV) whilst minim...Purpose: Adenosine stress CMR is commonly used to assess myocardial ischaemia. Obtaining high quality images requires maximising signal to noise ratio (SNR) over a large double-oblique field of view (FOV) whilst minimising artefacts. A 32-channel surface coil may provide a higher SNR over a larger FOV compared to standard coils, possibly leading to improved image quality. Materials and Methods: 50 adenosine perfusion CMR scans were performed on a Philips Achieva CV 1.5T, with either a 5 or 32-channel coil (25 patients each) using standardised acquisition protocols. 3 short axis slices were acquired per cardiac cycle and the resulting cine images were scored by two blinded CMR specialists on a quality scale of 1 to 5. Phantom studies were performed using similar acquisition parameters and the SNR was calculated and compared across a range of acceleration factors. Results: The mean patient age was 62 ± 11 years and 50% of patients were male. The image quality scores were higher using the 32-channel coil (mean 3.8 ± 0.7 vs 3.2 ± 0.9 p = 0.002). The average phantom SNR was greater for the 32-element coil across the range of acceleration factors measured (103 vs 86 p = <0.001). Conclusions: The 32-channel coil produces significantly higher quality images and a higher SNR than the 5-channel coil in routine perfusion CMR.展开更多
Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments...Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).展开更多
文摘Purpose: Adenosine stress CMR is commonly used to assess myocardial ischaemia. Obtaining high quality images requires maximising signal to noise ratio (SNR) over a large double-oblique field of view (FOV) whilst minimising artefacts. A 32-channel surface coil may provide a higher SNR over a larger FOV compared to standard coils, possibly leading to improved image quality. Materials and Methods: 50 adenosine perfusion CMR scans were performed on a Philips Achieva CV 1.5T, with either a 5 or 32-channel coil (25 patients each) using standardised acquisition protocols. 3 short axis slices were acquired per cardiac cycle and the resulting cine images were scored by two blinded CMR specialists on a quality scale of 1 to 5. Phantom studies were performed using similar acquisition parameters and the SNR was calculated and compared across a range of acceleration factors. Results: The mean patient age was 62 ± 11 years and 50% of patients were male. The image quality scores were higher using the 32-channel coil (mean 3.8 ± 0.7 vs 3.2 ± 0.9 p = 0.002). The average phantom SNR was greater for the 32-element coil across the range of acceleration factors measured (103 vs 86 p = <0.001). Conclusions: The 32-channel coil produces significantly higher quality images and a higher SNR than the 5-channel coil in routine perfusion CMR.
文摘Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).
文摘目的:探讨并比较颞下颌关节MRI成像中15通道头颅相控阵线圈和6通道dS Flex M表面线圈的临床应用价值,以指导临床应用工作。方法:对50例行颞下颌关节MRI扫描患者随机分配,25例患者应用15通道头颅相控阵线圈扫描,25例患者应用6通道dS Flex M表面线圈扫描。所有数据均设置相同感兴趣区(颞部、髁状突颈部、内侧肌肉、腮腺及脂肪区域),分别测量各区域的信噪比(signal to noise ratio,SNR)及对比噪声比(contrast to noise ratio,CNR),并应用SPSS 19.0软件进行量化分析。结果:3.0T MRI 15通道头颅相控阵线圈SNR和CNR均比6通道d S Flex M表面线圈高;应用15通道头颅相控阵线圈和6通道d S Flex M表面线圈扫描满足影像诊断要求的阳性率分别为95.83%、91.67%,2组比较差别无统计学意义(P>0.05)。结论:3.0T MRI 15通道头颅相控阵线圈和6通道d S Flex M表面线圈均可用于颞下颌关节MRI成像,常规成像建议用d S Flex M表面线圈,功能成像建议使用头颅相控阵线圈。
