Concurrent Demonstration of Cerebral Infarction and the Involved Pyramidal Tract

by 3D-FLAIR Imaging Using a Variable Refocusing Flip Angle

Kazuhiro Tsuchiya, Motoyuki Yamashita, Naoki Shimatani

Misako Yorimitsu, Motonori Kokan, Takeo Suzuki, Shuichi Ichisaka

Department of Radiology, Tokyo Teishin Hospital

Tokyo, Japan

☑ The author has no conflict of interest to disclose with respect to this presentation.

Background and Purpose

We have found that FLAIR imaging using a VISTA (Volume ISotropic TSE Acquisition) sequence can highlight some major nerve tracts by changing a refocusing flip angle (RFA)

from that (60°) recommended by the vendor for conventional FLAIR contrast.

We assessed the feasibility of the FLAIR VISTA sequence in demonstrating the pyramidal tract (PT) and an infarct that developed in its vicinity on one image.

Signal

Gx

Gy

Gz

RF

90° RF pulse

90+α/2

α α Refocusing pulse

Echo space ↓

3D non volume selective

VISTA （ Volume ISotropic TSE Acquisition ）

• Available for imaging of T1WI, T2WI, and FLAIR

• 3D non volume-selective 　→　 echo space↓, blurring↓

• Refocusing flip angle 　→ 　 pseudo steady state, long ETL

α α

3D FLAIR VISTA images obtained with an RFA of 110° show the pyramidal tract as a hyperintense structure.

RFA 40° RFA 70°

RFA 170° RFA 140°

RFA 110°

Normal volunteer (34F)

Contrast of the pyramidal tract changes according to the RFA.

Comparison of diffusion tensor color map and tractography shows good correspondence.

SNR/CNR assessments at various RFAs in 5 volunteers show 110 ° as a favorable value.

• Fifteen patients (9 men, 6 women; aged 45 to 87 years, average age 65.8 years ) of acute/subacute infarction who underwent MR imaging including the FLAIR VISTA sequence (RFA=110°) between June, 2013 and March, 2014.

Patients

• 1.5-T imager (PHILIPS Achieva Release 2.6)• Imaging parameters: TR/TE/TI, 6000/312/2000 ms; FOV,

250 mm; matrix, 208 x 208; slice thickness. 0.6 mm; SENSE factor, 2.8 (phase) x 2 (slice); flip angle, 90°; turbo factor, 140; and imaging time; 6 min 18 sec; scan plane, sagittal followed by reconstruction of coronal images

• Images were visually assessed by consensus reading of 2 experienced radiologists regarding the visualization of the pyramidal tract and the infarct using a three-point grading scale (3 = good, 2 = fair, 1 = poor).

Methods

Symptoms MR findings PTvisualization

62M transient weakness of LUE R temporal infarction 3

45M dysarthria, weakness of RUE L posterior limb of the internal capsule infarction 3

64F R hemiplegia, total aphasia L MCA area infarction 3

87F dysarthria, weakness of RUE L basal ganglia/corona radiata infarction 3

65F weakness of RUE, limb ataxia R thalamus infarction 3

87F DOC L frontotemporal infarction 3

65F weakness of LUE, limb ataxia R thalamus/posterior limb of the internal capsule infarction

3

79M DOC, L hemiparesis R thalamus/posterior limb of the internal capsule infarction

3

51M numbness of LUE, L hemiparesis R corona radiata/putamen, and frontal subcortical infarction

3

61M R hemiplegia L frontoparietal infarction 3

54F transient dysarthria, slight L facial palsy R posterior limb of the internal capsule infarction 3

56M dysarthria, headache R corona radiata infarction 3

70M dysarthria, slight R facial palsy L frontoparietal infarction 3

73M R hemiplegia, L concomitant deviation L PCA area infarction 3

68M weakness of RUE L posterior limb of the internal capsule infarction 3

*R : right, L : left, LUE : left upper extremity , RUE : right upper extremity, DOC : disturbance of consciousness MCA: middle cerebral artery, PCA: posterior cerebral artery

Patient clinical data and summary of MR findings

In all of the 15 cases, the PT was depicted on both sides.

FLAIR VISTA images also showed the PT and the adjacent infarct that caused motor paresis of a variable degree.

The average grading score was 3.

Summary of results

transient weakness of left upper extremity after right cervical pain

Case 1(62M)

transient weakness of left upper extremity after right cervical pain

Case 1(62M)

transient weakness of left upper extremity after right cervical pain

Case 1(62M)

dysarthria and weakness of right upper extremityCase 2(45M)

dysarthria and weakness of right upper extremityCase 2(45M)

weakness of right upper extremity and limb ataxiaCase 3(65F)

weakness of right upper extremity and limb ataxiaCase 3(65F)

weakness of right upper extremity and limb ataxiaCase 3(65F)

The PT was depicted on both sides in all cases probably reflecting histological characteristics of anisotropic fibers.

Limitation of this methodNot available in acute infarction that is not hyperintense on FLAIR images　

Advantages of this method 　This method may be available for lesions other than in-farct (e.g., tumors and demyelinating diseases).It may present different contrast of infarct from conven-tional 3D FLAIR (RFA=60°). → possibly depict infarct in an earlier stage than conventional method?

Discussion

Conclusion

The 3D FLAIR VISTA technique using a RFA of 110° readily

visualizes the relationship between the PT and cerebral

infarct involving it.