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 ID: 284805
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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 ShimataniMisako Yorimitsu, Motonori Kokan, Takeo Suzuki, Shuichi IchisakaDepartment of Radiology, Tokyo Teishin Hospital Tokyo, JapanSlide2
☑ The author has no conflict of interest to disclose with respect to this presentation.Slide3
Background and PurposeWe 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.Slide4
Signal
Gx
Gy
Gz
RF
90° RF pulse
90+α/2
α
α
Refocusing pulse
Echo space
↓
3D non volume selective
VISTA
（
V
olume
IS
otropic
T
SE
A
cquisition
）
Available for imaging of T1WI, T2WI, and FLAIR
3D non
volume-selective
→
echo
space
↓
, blurring
↓
Refocusing flip angle
→
pseudo steady
state, long
ETL
α
αSlide5
3D FLAIR VISTA images obtained with an RFA of 110° show the pyramidal tract as a hyperintense structure.Slide6
RFA
40°RFA 70°RFA 170°
RFA
140
°
RFA
110
°
Normal volunteer (34F)
Contrast of the pyramidal tract changes according to the RFA. Slide7
Comparison of
diffusion tensor color map and tractography shows good correspondence.Slide8
SNR/CNR assessments at various RFAs in 5 volunteers show 110 ° as a favorable value.Slide9
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.
PatientsSlide10
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).MethodsSlide11
SymptomsMR findingsPT
visualization62Mtransient weakness of LUER temporal infarction345Mdysarthria, weakness of RUEL posterior
limb of the internal capsule infarction
3
64F
R
h
emiplegia, total aphasia
L
MCA
area infarction
3
87F
dysarthria, weakness of RUEL basal ganglia/corona radiata infarction3
65F
weakness of RUE, limb ataxiaR thalamus
infarction3
87F
DOCL frontotemporal
infarction3
65Fweakness of LUE, limb ataxiaR thalamus/posterior limb of the internal capsule infarction
379MDOC, L hemiparesis
R thalamus/posterior limb of the internal capsule infarction351Mnumbness of LUE, L hemiparesis
R corona radiata/putamen, and frontal subcortical infarction361M
R hemiplegiaL frontoparietal infarction3
54F
transient dysarthria, slight L
facial palsyR posterior limb of the internal capsule infarction
356M
dysarthria
, headacheR
corona radiata infarction
3
70Mdysarthria, slight R facial palsy
L
frontoparietal infarction373M
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 findingsSlide12
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 resultsSlide13
transient weakness of left upper extremity after right cervical pain
Case 1(62M)Slide14
t
ransient weakness of left upper extremity after right cervical pain
Case 1
(62M)Slide15
t
ransient weakness of left upper extremity after right cervical pain
Case 1
(62M)Slide16
d
ysarthria and weakness of right upper extremityCase 2(45M)Slide17
d
ysarthria and weakness
of right upper extremity
Case 2
(45M)Slide18
weakness of right upper
extremity and limb ataxia
Case 3
(65F)Slide19
weakness of right upper
extremity and limb ataxia
Case 3
(65F)Slide20
weakness of right upper
extremity and limb ataxia
Case 3
(65F)Slide21
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 infarct (e.g., tumors and demyelinating diseases).It may present different contrast of infarct from conventional 3D FLAIR (RFA=60°). →
possibly depict
infarct in an earlier stage than
conventional method?
DiscussionSlide22
ConclusionThe 3D FLAIR VISTA technique using a RFA of 110°
readily visualizes the relationship between the PT and cerebral infarct involving it.