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J Magn Reson Imaging. 2015 Aug;42(2):269-79. doi: 10.1002/jmri.24802. Epub 2014 Dec 4.

Simultaneous imaging of radiation-induced cerebral microbleeds, arteries and veins, using a multiple gradient echo sequence at 7 Tesla.

Author information

1
The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California San Francisco, San Francisco, California, USA.
2
Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
3
Global Applied Science Laboratory, GE Healthcare, Menlo Park, California, USA.
4
Global Applied Science Laboratory, GE Healthcare, San Francisco, California, USA.
5
Department of Neurological Surgery, University of California San Francisco, San Francisco, California, USA.
6
Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, USA.

Abstract

BACKGROUND:

The purpose of this study was to implement and evaluate the utility of a multi-echo sequence at 7 Tesla (T) for simultaneous time-of-flight (TOF) MR-angiography (MRA) and susceptibility-weighted imaging (SWI) of radiation-induced cerebral microbleeds (CMBs), intracranial arteries, and veins.

METHODS:

A four-echo gradient-echo sequence was implemented on a 7T scanner. The first echo was used to create TOF-MRA images, while the remaining echoes were combined to visualize CMBs and veins on SWI images. The sequence was evaluated on eight brain tumor patients with known radiation-induced CMBs. Single-echo images were also acquired to visually and quantitatively compare the contrast-to-noise ratio (CNR) of small- and intermediate-vessels between acquisitions. The number of CMBs detected with each acquisition was also quantified. Statistical significance was determined using a Wilcoxon signed-rank test.

RESULTS:

Compared with the single-echo sequences, the CNR of small and intermediate arteries increased 7.6% (P < 0.03) and 9.5% (P = 0.06), respectively, while the CNR of small and intermediate veins were not statistically different between sequences (P = 0.95 and P = 0.46, respectively). However, these differences were not discernible by visual inspection. Also the multi-echo sequence detected 18.3% more CMBs (P < 0.008) due to higher slice resolution.

CONCLUSION:

The proposed 7T multi-echo sequence depicts arteries, veins, and CMBs on a single image to facilitate quantitative evaluation of radiation-induced vascular injury.

KEYWORDS:

7T; SWI; TOF-MRA; microbleeds; multi-echo; radiation effects

PMID:
25471321
PMCID:
PMC4876721
DOI:
10.1002/jmri.24802
[Indexed for MEDLINE]
Free PMC Article

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