Masami Yoneyama1, Hajime Tanji2, Tomoya Yamaki2, Daisuke Takahashi2, Makoto Obara1, Tomoyuki Okuaki3, and Marc Van Cauteren3
1Philips Electronics Japan, Tokyo, Japan, 2Kita-Fukushima Medical Center, Fukushima, Japan, 3Philips Healthcare Asia Pacific, Tokyo, Japan
Synopsis
Simultaneous acquisition of both MR angiography and MR neurography would be extremely helpful for diagnosing thoracic outlet syndrome. This study proposed a novel sequence, motion-sensitized driven-equilibrium (MSDE) prepared phase-cycling gradient echo (pcMSDE), for achieving simultaneous depiction of both MR angiography and MR neurography. By using this sequence, MR neurography images were obtained by MSDE (with motion sensitized gradient (MSG)) scan. MR angiography images were obtained by subtraction between “b0” scan (without MSG) and MSDE (with MPG) images. Additionally, this sequence could simultaneously offer the anatomical proton-density images and “self-fusion” images (MR NeuroAngiography) by using MR neurography and MR angiography. This sequence has great potential to help the diagnosis for any type of TOS. Further clinical investigation is needed.Purpose
Thoracic outlet syndrome (TOS) is a condition arising from compression of the subclavian vessel and/or brachial plexus as the structures travel from the thoracic outlet to the axilla1,2. TOS has been classified into several types, including neurogenic TOS (nTOS), arterial TOS (aTOS), and venous TOS (vTOS)3. MRI is increasingly used in the diagnosis of TOS. 3D contrast-enhanced MRA has recently been utilized in diagnosing vascular complications resulting from aTOS/vTOS2-4. On the other hand, MR neurography has been utilized for identification of fibrous bands impinging on the lower brachial plexus5. Hence, simultaneous acquisition of both MR angiography and MR neurography would be extremely helpful for diagnosing in any type of TOS.
In this study we proposed a novel sequence, motion-sensitized driven equilibrium (MSDE) prepared phase-cycling gradient echo (pcMSDE), for achieving simultaneous depiction of both MR angiography and MR neurography.
Methods
Scheme of pcMSDE sequence for simultaneously acquiring MR neurography and MR angiography is shown in Figure 1. We extended the phase-cycling Diffusion-Sensitized Driven-Equilibrium (pcDSDE) sequence6. This consists of two iMSDE7-prepared phase-cycling T1-turbo field-echo (T1TFE) sequences with/without motion proving gradients (MPG) to suppress/unsuppress the subclavian vessel signals.
To eliminate the T1-effects, which are given by T1TFE and deteriorate contrast by MSDE, phase-cycling scheme is applied8,9. Scheme of phase-cycling MSDE-TFE sequence is shown in Figure 2. This method requires the acquisition of two types of sequences (sequenceA and B). In sequenceA and B, the phases of DSDE flip-back pulse and the TFE pulses are reversed. As a result, neurography images are obtained by addition of respective phase-sensitive images, and anatomical (proton-density weighted) images are obtained by addition of both magnitude-images from the identical data.
A total of six volunteers were examined with 3.0T whole-body clinical system (Ingenia CX, Philips Healthcare). The study was approved by the local IRB, and written informed consent was obtained from all subjects. Imaging parameters were; Coronal, voxel size=1.0*1.5*3mm, 40 slices, b-value=7.5s/mm2, MSDE preparation time (prep-time)=90ms, gshot interval=3000ms, flip angle=8°, turbo factor=73, ProSet 1331, and total acquisition time=8m36s.
Results and Discussion
Representative images of MR neurography and MR angiography by using pcMSDE-TFE sequence are shown in Fig.3. MR neurography images were obtained by MSDE (with MPG) scan. pcMSDE-TFE clearly shows both anatomies and courses of brachial plexus on the MIP images. On the other hand, MR angiography images were obtained by subtraction between “b0” scan (without MPG) and MSDE (with MPG) images. That is, subtraction of vessel suppressed image from "bright blood" image provides a selective angiogram. Furthermore, pcMSDE could simultaneously offer the anatomical proton-density images and “self-fusion” images (MR NeuroAngiography) by using MR neurography and MR angiography datasets (Fig.4). The anatomical images and MR NeuroAngiography may also help the diagnosis of TOS by giving further detailed anatomic relation.
Conclusion
This study showed a new scheme for simultaneous acquisition of MR angiography and MR neurography by using phase-cycled MSDE-TFE sequence. This sequence has great potential to help the diagnosis for any type of TOS. Further clinical investigation is needed.
Acknowledgements
No acknowledgement found.References
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