Fast spin echo sequence

Most clinical examinations apply robust spin-echo or fast spin-echo sequences. These types of sequences provide tissue contrast changes by variation of the chosen repetition time TR (time interval between succeeding RF excitations) and echo time TE (time delay between RF excitation and signal acquisition). 

The symbol denotes convolution. Thus, the effect of varying TE and TR in pulse sequences on resolution can be followed by a PSF analysis.Robson et al have outlined an experimental method for measuring the PSF. Different schemes for the phase encoding employed in pulse sequences can lead to different fe-space weighting functions and thus affect resolution. Zhou et al analyzed three different fc-space sampling schemes and the corresponding PSFs for a fast spin echo sequence in order to... 

Electrodes are left externalized to confirm their position by MRI. Scans are performed using 1.5 T Edge equipment software version 9.3 (Marconi Medical Systems, Cleveland, Ohio), using T2 weighted fast spin echo sequence (echo time 11 ms repetition time 4070 msec field of view 16.0 cm 256 x 256 matrix). Sections are oriented parallel and perpendicular to the AC-PC line for axial and frontal views, and parallel to the midsagittal plane for sagittal sections [Velasco et al, 2000b, 2002]. 

Katayama M, Masui T, Kobayashi S et al (2001) Fat-suppressed T2-weighted MRI of the liver comparison of respiratory-triggered fast spin-echo, breath-hold singleshot fast spin-echo, and breath-hold fast-recovery fast spin-echo sequences. J Magn Reson Imaging 14 439-449... 

Masui T, Katayama M, Kobayashi S, Sakahara H, Ito T, Nozaki A (2001) T2-weighted MRl of the female pelvis comparison of breath-hold fast-recovery fast spin-echo and nonbreath-hold fast spin-echo sequences. J Magn Reson Imaging 13 930-937... 

T2-weighted gradient-echo sequences with the steady-state free precession (SSFP) technique were initially usedby Wallner et al. (1991), Morimoto et al. (1992),HALL-CRAGGsetal. (1993), and IsmzAKiet al. (1993). Subsequently, other investigators have utilized two-dimensional (2D) and three-dimensional (3D) heavily T2-weighted fast spin-echo sequences... 

Fig. 11.5a,b. MR imaging of a patient with hepatocellular carcinoma and tumor thrombus within the right portal vein, a The dynamic liver study obtained at the arterial phase of liver enhancement shows a fan-shaped area of hyperintensity with a broad capsular base corresponding to the THAD in the territory affected by the portal flow interruption, b On the T2-weighted fast spin-echo sequence a tumoral portal vein thrombus is depicted causing vessel enlargement... 

TSE, turbo spin echo also known as FSE, fast spin echo TR, repetition time TE, time to echo TI, time for inversion coronal oblique, parallel to the long axis of the uterus axial oblique, parallel to the short axis of the uterus TRUFISP, fast induction steady state potential gradient sequence (Siemens Medical, Germany). 

Tl Weighted Spin Echo Sequences 62 T2 Weighted Spin Echo Sequences 64 Proton Density Imaging 64 Fast Spin Echo Techniques 64... 

The sequences may obscure sclerosis or marrow oedema due to poor marrow fat contrast compared to TlWl or fat saturated proton density fast spin echo (FS PD FSE) sequences. 

T2 or proton density fast spin echo fat suppressed (PD FSE FS) are useful for evaluating marrow oedema, articular cartilage, ligaments, tendons, synovium and meniscal morphology. They are a commonly used sequence for all appendicular joint imaging. TE values are typically less than 60 ms and TR values greater than or equal to 3000 ms. TE values are around 40-50 ms to optimise image quality. 

Gradient echo-based sequences, such as constructive interference in steady state sequences, also are used for the imaging of the inner ear region (Casselman et al. 1996 Held et al. 1997). However, the specific absorption rate of these sequences may be higher than that of 3D fast spin echo-based sequences, and susceptibility artifacts may be more pronounced, especially at 3 T scanners. 

Typically, 3D FT volume studies have been conducted with gradient echo sequences that could offer short acquisition time due to their short repetition time. Currently, 3D fast or turbo spin echo sequences can be applied clinically, and they offer pure T2-weighted volumetric images without susceptibility artifacts. Although fast or turbo spin echo sequences utilize... 

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