Association Between Signal Intensity Gradient of Cerebral Arteries From Time-of-flight Magnetic Resonance Angiography and Clinical Outcome in Patients With Lenticulostriate Artery Infarction
Conditions: Ischemic Stroke, Acute
Sponsor: Chonbuk National University Hospital

Association between signal intensity gradient of cerebral arteries from time-of-flight 
magnetic resonance angiography and clinical outcome in patients with lenticulostriate 
infarction: A multicenter retrospective cohort study 
 
                                           Date of the document: August 5th 2020 

Study population 
This study is a multi-center, retrospective cohort study for all consecutive patients. From 
January 2015 to March 2021, patients who were diagnosed with acute ischemic stroke in the 
lenticulostriate artery (LSA) territory were registered at three centers (Jeonbuk National 
University Hospital, Samsung Medical Center, and Gunsan Medical Center). The 3 centers 
have their own characteristics: Gunsan Medical center is in a small city where about 300,000 
citizens live, Jeonbuk National University Hospital is in a medium sized city where about 
650,000 citizens live, and Samsung Medical Center is in a capital city where about 
10,000,000 citizens live).  
The inclusion criteria were as follows: (1) Patients aged 18 years or older who had 
brain magnetic resonance imaging (MRI) for acute ischemic stroke within 3 days, (2) Patients 
who underwent diffusion-weighted imaging (DWI) and apparent diffusion coefficient of the 
cerebral parenchyma, and cerebral angiographic measurements, in which, intracranial arteries 
should be examined by time-of-flight (TOF) techniques, and (3) A patient with high signal 
intensity lesions in the unilateral LSA territory on DWI.  
The exclusion criteria are as follows. (1) Patients younger than 18 years of age, (2) 
Patients with moderate to severe (>50%) stenosis or occlusion of the major intracranial and 
extracranial arteries, including internal carotid artery (ICA), middle cerebral artery (MCA), 
anterior cerebral artery (ACA), posterior cerebral artery (PCA), basilar artery (BA), and 
vertebral artery (VA), (3) Patients whose ischemic stroke was due to or related with cardiac or 
rare etiology (e.g., arterial dissection, moyamoya disease). The present study was conducted 
following approval from the ethics review committee in each hospital. 
 
Acquisition of clinical data 

Demographic and clinical information on cardiovascular risk factors (hypertension, diabetes 
mellitus, hyperlipidemia, and smoking history), laboratory findings at admission (including 
complete blood count, lipid profiles, serum glucose level, HbA1c) were extracted from 
electronic medical records. A neurological severity in each patient was monitored using 
National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) during 
hospitalization, and were collected. 
 
Clinical outcome 
As a clinical outcome of the patients with the LSA infarction, mRS of discharge or 7th day 
was used to define clinical status: mRS 2 or less was defined as a good outcome group and 3 
or more as a poor outcome group. 
 
Time of Flight Magnetic Resonance Angiography 
The MRA protocols in 3 hospital were described in detail, as in supplementary table 1. We 
used a 3.0T MR of a SENSE 32 Channel cardiac coil (Philips Medical Systems, Achieva, The 
Netherlands) to obtain a three-dimensional intracranial and extracranial TOF image. The 
parameters used to obtain TOF-MRA are as follows. TR = 23.0ms, TE = 3.5ms, Resolution = 
300X220, FOV (field of view) = 180 mm2, 160 slices, FA (flip angle) = 20.0°, scan duration = 
1 minute 53 seconds – needs to be rewrite 
 
Measurement of TOF MRA SIG from cerebral arteries 
TOF MRA SIGs from cerebral arteries (both ICA, MCA, ACA, PCA, VA and one BA) were 
measured with a semi-automated software (VINT, Mediimage, Inc. Seoul, Republic of 

Korea), as reported previously.1 In brief, the signal intensities at the iso-point (Φa; signal 
intensity at position A [Xa] along the arterial contour line) and at the inner point (Φb; signal 
intensity at position B [Xb]) were calculated by using a trilinear interpolation algorithm based 
on the positions and signal intensities in the eight neighboring voxels. The signal intensities 
of TOF-MRA were normalized to eliminate the offset and scale effects across the MRA 
datasets of participants. For each iso-point (position A), the SIG was calculated from the 
difference in signal intensities between points A and B as follows: 
 
SIG, SI/mm = (Φb – Φa) / │Xb – Xa│ 
 
 
 
(1) 
 
The mean values of SIG of cerebral arteries were obtained, as shown in Figure 1. The arterial 
SIG measurement was performed in the straight segment as possible in ICA (at the C1 distal 
portion before a horizontal intrapetrous segment), VA (V4 distal, just before a conjoined BA), 
and BA (mid to distal portion). For the MCA and ACA, the initial 1/2 or 1/3 segment was 
chosen. For the PCA, P2 segment (distal to posterior communicating artery) was selected for 
a measurement. 
 
Statistical analysis 
Descriptive data for the clinical characteristics and laboratory findings of the participants 
were expressed as a mean ± standard deviation or percentage as appropriate. Kolmogorov-
Smirnov test was performed for distributional adequacy. A student t-test or chi-square test 
was used to assess differences as appropriate. Logistic regression analyses were performed to 
determine the independent association between the SIG values in cerebral arteries and 
favorable outcome, adjusting for all possible confounders. Statistical analyses were 
conducted using SPSS version 20 (SPSS, Chicago, IL, USA).