Optimizing isotropic three-dimensional fast spin-echo methods for imaging the knee

Abstract

Purpose To optimize acquisition parameters for three-dimensional fast spin-echo (3D FSE) imaging of the knee. Materials and methods The knees of 8 healthy volunteers were imaged in a 3 T MRI scanner using an 8-channel knee coil. A total of 146 intermediate-weighted isotropic resolution 3D FSE (3D-FSE-Cube) images with varied acquisition parameter settings were acquired with an additional reference scan performed for subjective image quality assessment. Images were graded for overall quality, parallel imaging artifact severity and blurring. Cartilage, muscle and fluid signal-to-noise ratios and fluid-cartilage contrast-to-noise ratios were quantified by acquiring scans without radiofrequency excitation and custom-reconstructing the k-space data. Mixed effects regression modeling was used to determine statistically significant effects of different parameters on image quality. Results Changes in receiver bandwidth, repetition time and echo train length significantly affected all measurements of image quality (p < .05). Reducing bandwidth improved all metrics of image quality with the exception of blurring. Reader agreement was slight to fair for subjective metrics, but overall trends in quality ratings were apparent. Conclusion We used a systematic approach to optimize 3D-FSE-Cube parameters for knee imaging. Image quality was overall improved using a receiver bandwidth of ±31.25 kHz, and blurring increased with lower bandwidth and longer echo trains.

Three-Dimensional Isotropic Fat-Suppressed Proton Density-Weighted MRI at 3 Tesla Using a T/R-Coil Can Replace Multiple Plane Two-Dimensional Sequences in Knee Imaging

“…The latter is difficult to fully account for in sagittally oriented 2 D slices and likely leads to partial volume effects that The significantly lower incidence of artifacts in 3D-PDwFS was mostly related to the decreased pulsation artifacts that are usually observed in 2D-PDwFS, especially in sagittal planes due to AP phase-encoding direction. These were not observed in sagittal MPR of 3D-PDwFS and may be attributed to the excitation pulse that covers a larger slab in 3D-PDwFS [5,7,24,26,27]. This has certain advantages in the case of preparation pulses, e. g. for fat suppression or inversion.…”

Regional Articular Cartilage Abnormalities of the Hip

“…Also, an intermediate-weighted 3D FSE sequence with isotropic resolution (Cube, GE Healthcare) was shown to detect cartilage lesions with a significantly higher sensitivity than a routine protocol [28], and this technique was optimized regarding image quality and motion artifacts [29]. Three-dimensional FSE sequences with isotropic spatial resolution allow reconstructions in arbitrary imaging planes and are currently adapted to hip cartilage imaging; the preliminary results with these sequences are promising, as shown in Figure 1.…”

Can a single isotropic 3D fast spin echo sequence replace three-plane standard proton density fat-saturated knee MRI at 1.5 T?

“…Up until now, the majority of studies assessing 3D SE sequences in the knee have been undertaken on 3-T MRI systems. [2][3][4][5][6][7][8][9][10][11] However, in common with many centres, our institution employs a 1.5-T system for the majority of its routine knee MRI studies. With acquisition time being a key factor in knee imaging protocols, our aim was to assess whether reconstructions obtained from a single isotropic 3D FSE PD (FS) sequence could replace the 3 PD (FS) sequences in our standard protocol on a 1.5-T system (Siemens Avanto, Erlangen, Germany).…”