新型口服对比剂茶在MRCP中的临床试用

目的评价一种新型口服对比剂——茶叶（日照绿茶）为原料研制的磁共振口服阴性对比剂在腹部MRCP诊断中的价值和可行性,为临床MRCP检查应用提供一种理想对比剂,以进一步促进MRCP检查的发展。方法以水为参照物,将不同浓度的茶对比剂置于磁共振中进行同一序列的扫描,比较不同浓度的茶对比剂对成像信号的影响。在相同情况下选择17例志愿者对口服茶对比剂前后进行MRCP成像,对检查结果进行分析、综合。结果不同浓度的茶对比剂产生不同的信号,清晰度不同,经体外试验确定最佳浓度的茶中,锰的浓度为12．04±0．22mg／L。此浓度下的茶对比剂,信号与水相反,即T1高信号,T2低信号。MRCP成像抑制了胃、十二指肠道内的液体高信号,使胰胆管周围背号干净,突出胰胆管内的液体高信号成分,图像质量显著性提高（p〈0．05）。结论茶作为天然饮品,服用后安全,无毒副作用,对胃肠道无刺激,在肠腔内不发酵,不产生气体,充盈肠腔充分,保证肠腔内信号均匀一致。利用茶叶中锰的特性将茶作为磁共振MRCP检查口服阴性对比剂,不需要经过药物试验即可应用。在MRCP检查中应是一种理想的口服对比剂。     

Advanced dynamic statistical parametric mapping with MEG in localizing epileptogenicity of the bottom of sulcus dysplasia

Objective

To investigate whether advanced dynamic statistical parametric mapping (AdSPM) using magnetoencephalography (MEG) can better localize focal cortical dysplasia at bottom of sulcus (FCDB).

Noise-Optimized Virtual Monoenergetic Dual-Energy CT Improves Diagnostic Accuracy for the Detection of Active Arterial Bleeding of the Abdomen

Purpose

To evaluate diagnostic accuracy of a noise-optimized virtual monoenergetic imaging (VMI+) reconstruction technique for detection of active arterial abdominal bleeding on dual-energy (DE) CT angiography compared with standard image reconstruction.

Image quality dependence on in-plane positions and directions for MDCT images

Objective

The present study was performed to examine the dependence of image quality on in-plane position and direction in computed tomography (CT) imaging using the modulation transfer function (MTF), noise power spectrum (NPS) and analysis of signal-to-noise ratio (SNR). For detailed analysis of SNR, the low-contrast detectability was compared using simulated small low-contrast objects.

Materials and methods

Three models of multidetector-row CT (MDCT) were employed. The measurement positions for MTF were set to the isocentre and several peripheral areas, and NPS and SNR were calculated for the isocentre and 128 mm off-centre. To evaluate directional dependence, the one-dimensional physical properties were measured separately in the radial and azimuthal directions. Seven radiological technologists also performed a perceptual detection study at the different in-plane positions using computer-simulated low-contrast images.

Results

The results of MTF and SNR differed between the isocentre and the peripheral area. The MTF values also tended to decrease with distance from the isocentre, and the SNR values in the low frequency range for the peripheral area were superior to those for the isocentre. In the detection study, the low-contrast detectability in the peripheral area was 13-40% higher than the value in the isocentre.

Conclusion

The results of the present study indicated that clinical CT images have remarkable non-uniformity of image quality. Therefore, the detailed analysis performed in this study will provide useful information for the development of advanced image processing applications, such as computer-aided diagnosis (CAD) and de-noising of CT images.     

Evaluation of multicoil breast arrays for parallel imaging

Purpose:

To evaluate three multicoil breast arrays for both conventional and SENSE‐accelerated imaging.

Materials and Methods:

Two commercially available 8‐element coils and a prototype 16‐element coil were compared. One 8‐element array had adjustable coils located next to the breast tissue and the other had a fixed coil arrangement; both were designed to allow parallel imaging in the left–right direction. The 16‐element coil was designed to have coil sensitivity variation in both the left–right and superior–inferior directions, and also had adjustable coils. Their performance was assessed in terms of signal‐to‐noise ratio (SNR), g‐factor, and uniformity with a custom‐built phantom.

Results:

The 16‐element array with adjustable coils provided the highest SNR, while the 8‐element coil with a fixed coil arrangement had the best uniformity. All coils performed well for SENSE acceleration in the left–right direction. The 8‐element coils did not have the capability for acceleration in the superior–inferior direction across the whole volume. The 16‐element coil enabled acceleration in the superior–inferior direction in addition to the left–right direction.

Conclusion:

Smaller, adjustable coil elements located next to breast tissue can provide greater SNR than larger, fixed coil elements. A multicoil breast array with high intrinsic SNR and low g‐factors enables high‐quality parallel imaging. J. Magn. Reson. Imaging 2010; 31: 328–338. © 2010 Wiley‐Liss, Inc.