[髌骨软骨的T2弛豫时间——1.5特斯拉和3特斯拉时的整体及局部可重复性]

[T2 relaxation time in patellar cartilage--global and regional reproducibility at 1.5 tesla and 3 tesla].

作者信息

Glaser C, Horng A, Mendlik T, Weckbach S, Hoffmann R-T, Wagner S, Raya J G, Horger W, Reiser M

机构信息

Institut für Klinische Radiologie, Klinikum der Universität München Grosshadern.

出版信息

Rofo. 2007 Feb;179(2):146-52. doi: 10.1055/s-2006-927203. Epub 2007 Jan 29.

DOI:10.1055/s-2006-927203

PMID:17262244

Abstract

PURPOSE

Evaluation of the global and regional reproducibility of T2 relaxation time in patellar cartilage at 1.5 T and 3 T.

MATERIALS AND METHODS

6 left patellae of 6 healthy volunteers (aged 25 - 30, 3 female, 3 male) were examined using a fat-saturated multiecho sequence and a T1-w 3D-FLASH sequence with water excitation at 1.5 Tesla and 3 Tesla. Three consecutive data sets were acquired within one MRI session with the examined knee being repositioned in the coil and scanner between each data set. The segmented cartilage (FLASH sequence) was overlaid on the multiecho data and T2 values were calculated for the total cartilage, 3 horizontal layers consisting of a superficial, intermedial and deep layer, 3 facets consisting of a medial, median (ridge) and lateral facet (global T2 values) and 27 ROIs/MRI slices (regional T2 value). The reproducibility (precision error) was calculated as the root mean square average of the individual standard deviations [ms] and coefficients of variation (COV) [%].

RESULTS

The mean global reproducibility error for T2 was 3.53 % (+/- 0.38 %) at 1.5 Tesla and 3.25 % (+/- 0.61 %) at 3 Tesla. The mean regional reproducibility error for T2 was 8.62 % (+/- 2.61 %) at 1.5 Tesla and 9.66 % (+/- 3.37 %) at 3 Tesla. There was no significant difference with respect to absolute reproducibility errors between 1.5 Tesla and 3 Tesla at a constant spatial resolution. However, different reproducibility errors were found between the cartilage layers. One third of the data variability could be attributed to the influence of the different cartilage layers, and another 10 % to the influence of the separate MRI slices.

CONCLUSION

Our data provides an estimation of the global and regional reproducibility errors of T2 in healthy cartilage. In the analysis of small subregions, an increase in the regional reproducibility error must be accepted. The data may serve as a basis for sample size calculations of study populations and may contribute to the decision regarding the level of detail of an evaluation of study data.

摘要

目的

评估1.5T和3T条件下髌骨软骨T2弛豫时间的整体及区域可重复性。

材料与方法

对6名健康志愿者（年龄25 - 30岁，3名女性，3名男性）的6个左髌骨进行检查，使用脂肪饱和多回波序列和T1加权3D-FLASH序列，并在1.5T和3T条件下进行水激发。在一次MRI检查中采集三个连续数据集，每次采集之间将被检查的膝关节重新放置在线圈和扫描仪中。将分割后的软骨（FLASH序列）叠加在多回波数据上，并计算整个软骨、由浅层、中层和深层组成的3个水平层、由内侧、中间（嵴）和外侧小面组成的3个小面（整体T2值）以及27个感兴趣区/ MRI切片（区域T2值）的T2值。可重复性（精度误差）计算为各个标准差[ms]的均方根平均值和变异系数（COV）[%]。

结果

1.5T时T2的平均整体可重复性误差为3.53%（±0.38%），3T时为3.25%（±0.61%）。1.5T时T2的平均区域可重复性误差为8.62%（±2.61%），3T时为9.66%（±3.37%）。在恒定空间分辨率下，1.5T和3T之间的绝对可重复性误差无显著差异。然而，在软骨层之间发现了不同的可重复性误差。三分之一的数据变异性可归因于不同软骨层的影响，另外10%可归因于单独MRI切片的影响。