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Table of Contents    
CORRESPONDENCE
Year : 2018  |  Volume : 66  |  Issue : 1  |  Page : 283-284

Arterial spin labeling


1 Neuroradiology Section, Department of Radiology, Seoul National University Hospital, Seoul, South Korea
2 Department of Radiology, Yashoda Hospital, Somajiguda, Hyderabad, Telangana, India

Date of Web Publication11-Jan-2018

Correspondence Address:
Dr. Ankit Balani
61, Shyam Nagar, Pal Link Road, Jodhpur, Rajasthan
South Korea
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.222882

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How to cite this article:
Balani A, Choi SH, Chatur C, Lee EJ. Arterial spin labeling. Neurol India 2018;66:283-4

How to cite this URL:
Balani A, Choi SH, Chatur C, Lee EJ. Arterial spin labeling. Neurol India [serial online] 2018 [cited 2019 Apr 23];66:283-4. Available from: http://www.neurologyindia.com/text.asp?2018/66/1/283/222882




Sir,

We read with a great deal of interest the manuscript titled “Perfusion MR imaging of enhancing brain tumors: Comparison of arterial spin labeling technique with dynamic susceptibility contrast technique” by Soni et al.,[1] in the September – October 2017 issue of Neurology India, Volume 65, Issue 5 along with the editorial debates titled “Can arterial spin labeling really replace dynamic susceptibility contrast perfusion techniques for assessing brain tumours in clinical practice?” by Patel et al.,[2] and “Arterial spin labeling: A novel promising perfusion technique – Can it be a replacement to dynamic susceptibility contrast MRI ?” by Pungavkar et al.,[3] discussing the pros and cons of arterial spin labelling vis a vis dynamic susceptibility contrast magnetic resonance imaging (MRI). The manuscripts are intelligently written, providing insight into the promising new technique of arterial spin labeling (ASL) and comparing it with dynamic susceptibility contrast MRI. We would like to make a few pertinent contributions.

In the editorial debate, Patel et al., mention “This is at the expense of a lower signal-to-noise ratio, lower temporal and spatial resolution and greater susceptibility artefact from the metallic hardware, blood, large vessels and air interfaces” while Pungavkar et al., in their article mention “ASL, being a fast spin echo (FSE) based sequence, has the advantage of insensitivity to susceptibility variations caused by haemorrhage or post-surgical intervention” which may seem to be contradictory to the readers. This apparent contradiction is due to difference of readout sequence which we wish to clarify to the readers. ASL makes use of fast imaging techniques for readout. Until recently, echo planar imaging (EPI) has been the most commonly used acquisition technique. However, there has been a gradual shift to more advanced alternative readouts such as three dimensional (3D)-gradient and spin echo (GRASE) and 3D rapid acquisition relaxation enhanced (RARE) combined with spiral readout trajectory.[4] These advanced 3D readout techniques provide better signal-to-noise ratio compared to 2D acquisitions, can allow single shot acquisition of the entire volume of interest, reducing slice dependent variation of signal and reduced susceptibility artefacts. The signal loss and image distortions due to susceptibility variations from blood products, surgical material, air interfaces, metallic hardware etc., were a significant problem with EPI readout techniques; however, 3D fast spin echo readout is relatively immune to off-resonance effects due to susceptibility variations near the imaging plane.[5] As the 3D readout is the recommended readout technique, these artefacts are not likely to limit the utility of ASL.

We wish to add the utility of superselective ASL in neurooncology, which has not been discussed in the editorial debate. Superselective ASL is a novel technique that enables selective labeling of extracranial and intracranial arteries non-invasively without the use of contrast media. Such information can otherwise be obtained by catheter angiography which is an invasive technique and exposes the patient to radiation and iodinated contrast media. Superselective ASL can help us identify a variable vascular architecture, permitting us to differentiate between the single and multi- compartmental vascular supply of the tumor (especially of a meningioma), which is helpful for surgeons in planning the approach and in reacting to the intraoperative bleeding. This information can be helpful for preoperative embolisation and can prevent the need for an invasive transfemoral catheter angiography for delineating vascular supply and for selecting candidates for preoperative embolisation. Superselective ASL makes the differentiation of intra- and extraaxial tumors possible by delineating the feeding arteries, adding to the knowledge provided by the conventional MRI sequences. In addition, it may help to differentiate tumor feeding vessels from en-passent feeders, thereby estimating possible complications from the preoperative devascularisation of tissues.[6] These are the other advantages of ASL over dynamic susceptibility contrast MRI in neurooncology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Soni N, Dhanota DPS, Kumar S, Jaiswal AK, Srivastava AK. Perfusion MR imaging of enhancing brain tumors: Comparison of arterial spin labeling technique with dynamic susceptibility contrast technique. Neurol India 2017;65:1046-52.  Back to cited text no. 1
[PUBMED]  [Full text]  
2.
Patel MD, Sawlani V. Can arterial spin labelling really replace dynamic susceptibility contrast perfusion techniques for assessing brain tumours in clinical practice? Neurol India 2017;65:977-8.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Pungavkar SA, Yanamandala R. Arterial spin labelling: A novel promising perfusion technique - Can it be a replacement to dynamic susceptibility contrast MRI ? Neurol India 2017;65:979-81.  Back to cited text no. 3
[PUBMED]  [Full text]  
4.
Grade M, Hernandez Tamames JA, Pizzini FB, Achten E, Golay X, Smits M. A neuroradiologist's guide to arterial spin labeling MRI in clinical practice. Neuroradiology 2015;57:1181-202.  Back to cited text no. 4
    
5.
Amukotuwa SA, Yu C, Zaharchuk G. 3D Pseudocontinuous arterial spin labeling in routine clinical practice: A review of clinically significant artifacts. J Magn Reson Imaging 2016;43:11-27.  Back to cited text no. 5
    
6.
Helle M, Jansen O, Nabavi A, Norris D, Rüfer S, van Osch M. Presurgical assessment of the feeding vasculature in extra-axial tumors with superselective arterial spin labeling. Proceedings of the 19th Annual Meeting ISMRM, Montreal, QC, Canada, 2011; 2429  Back to cited text no. 6
    




 

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