Patients and groups
AIS patients admitted to the Tianjin First Central Hospital were recruited for the study. All patients had an apparent onset of neurological impairment (communication dysfunction, unilateral face or limb numbness, etc.). Acute cerebral infarction was confirmed by the admission MRI scan, which included T1WI, T2WI, DWI, DKI, Magnetic Resonance Angiography (MRA), and perfusion-weighted imaging (PWI). The clinical history, including demographics, risk factors, neurological evaluation, and NIHSS score 18, was collected. The NIHSS score ranged from 0 to 42, where 0–1 was defined as normal or nearly normal; 2–4 was considered mild; 5–15 was considered moderate; 16–20 was considered moderate-severe and 21–42 was defined as a severe stroke. The exclusion criteria were small lesions (minimum diameter < 10 mm), bilateral lesions, intracranial hemorrhage or lesions, craniocerebral trauma or surgery history, and endovascular or intravenous thrombolytic therapy.
During the study period, 250 AIS patients were collected. Of them, 161 patients were excluded due to other intracranial space occupation or history of craniocerebral surgery, bilateral cerebral infarction (62 patients), and the maximum diameter of DWI high signal < 10 mm. Finally, 89 patients were enrolled in the present study (Fig. 1). After three months of admission, the mRS score was assessed and used as an indicator of the prognosis of AIS 19, with mRS ranging from 0 (asymptomatic) to 6 (death). The good prognosis was defined as mRS score ≤ 2, and the poor prognosis was defined as mRS score ≥ 3 at 90 days after discharge. According to the 90-day mRS score, 89 patients were divided into two groups, and their demographic characteristics are shown in Table 1.
Table 1
The demographic, clinical and imaging features in different groups of patients (mean ± SD).
| All patients (n = 89) | Patients with good prognosis (n = 42) | Patients with poor prognosis (n = 47) | r | P |
Clinical risk factors |
Age, y | 61.854 ± 9.715 | 61.119 ± 9.793 | 62.511 ± 9.702 | 0.049 | 0.647 |
Gender | 68/21 | 28/14 | 40/7 | -0.217# | 0.041* |
NIHSS score | 4.876 ± 3.867 | 3.357 ± 2.783 | 6.234 ± 4.208 | 0.372 | < 0.001*** |
Hypertension | 72/17 | 35/7 | 37/10 | 0.059# | 0.581 |
Diabetes | 35/54 | 17/26 | 18/29 | 0.022# | 0.834 |
Smoking | 52/37 | 23/19 | 29/18 | -0.07# | 0.507 |
Drinking | 24/75 | 9/33 | 15/32 | -0.118# | 0.266 |
Previous Stroke History | 21/78 | 12/30 | 9/38 | 0.111# | 0.296 |
Imaging metrics |
Lesion size | 3080.855 ± 5321.363 | 2179.490 ± 3897.603 | 3886.330 ± 6263.121 | 0.176 | 0.100 |
Types Cortex/ Subcortical/ Basal ganglia/ Subtentorial | 23/19/31/16 | 10/6/14/12 | 13/13/17/4 | 7.002# | 0.072 |
rMD | 0.621 ± 0.123 | 0.681 ± 0.117 | 0.566 ± 0.103 | -0.449 | < 0.001*** |
rMK | 1.496 ± 0.247 | 1.364 ± 0.173 | 1.614 ± 0.246 | 0.545 | < 0.001*** |
rMTT | 1.480 ± 0.301 | 1.403 ± 0.273 | 1.549 ± 0.310 | 0.261 | 0.010* |
rTTP | 1.289 ± 0.170 | 1.232 ± 0.155 | 1.340 ± 0.169 | 0.325 | 0.001** |
rCBF | 0.552 ± 0.210 | 0.630 ± 0.213 | 0.482 ± 0.182 | -0.348 | < 0.001*** |
rCBV | 0.681 ± 0.214 | 0.739 ± 0.188 | 0.628 ± 0.224 | -0.268 | 0.010* |
* P < 0.05 ** P < 0.01 *** P < 0.001 #represents independent chi-square test and the correlation coefficient r obtained by Pearson contingency coefficient. For the remaining factors, spearman correlation test was employed to get the r and p values. |
MR Protocol.
All MRI examinations (including T1WI, T2WI, DWI, DKI, MRA, and PWI) were performed using a 3T Siemens Trio imager with a 32-channel head coil (Siemens Healthineers, Erlangen, Germany). The DWI was performed using a single-shot echo-planar sequence with repetition time (TR)/echo time (TE) = 5000/93 ms, field of view (FOV) = 221 \(\times\) 211 mm², matrix = 183 \(\times\) 384, axial slices (number/thickness/gap) = 20/5.0 mm/1.5 mm, and three diffusion directions with two b values (0, 1000 s/mm²); DKI was performed using a multi-band echo-planar sequences with TR/TE = 3000/95 ms, FOV = 230 \(\times\) 230 mm², matrix = 183 \(\times\) 384, axial slices (number/thickness/gap) = 20/5.0 mm/1.5 mm, and 20 diffusion directions with three b values (0, 1000, 2000 s/mm²). PWI was collected after the injection of intravenous contrast agent, TR/TE = 1480/32 ms, FOV = 230 \(\times\) 230 mm², axial slices (number/thickness/gap) = 20/5/1.25 mm; MRA sequence was performed using TOF-3D technology, TR/TE = 27/3.59 ms, FOV = 230 \(\times\) 230 mm², slice thickness = 0.7 mm; total scan time for the imaging protocol was about 15 minutes.
Ethical considerations.
The study protocol was approved by the Ethics Committee of Tianjin First Central Hospital, all participants gave their written informed consent. All methods were carried out in accordance with relevant guidelines and regulations.
Data processing.
The DKI data were converted to the NIfTI format and then processed for motion correction, eddy current correction, and Gaussian smoothing noise reduction (FMRIB Software Library, http://www.fmrib.ox.ac.uk/fsl/). The mean diffusivity (MD) and mean kurtosis (MK) maps were derived from diffusional kurtosis estimator software (https://www.nitrc.org/projects/dke/).
The PWI data were post-processed by Siemens "Neuro Perfusion" software package to obtain the mean transit time (MTT) (s) and the time to peak (TTP) (s), cerebral blood flow (CBF) (ml/min/100g), and cerebral blood volume (CBV) (ml/100g).
The lesion was delineated in MRIcron software, and the ROI was saved and copied to the DKI and PWI maps to obtain MD, MK, MTT, TTP, CBF, and CBV values. In addition to the acute infarct lesion, the ROI was also flipped to the opposite side to obtain the above metrics of the contra-lateral normal brain regions. The relative metrics of diffusion and perfusion were the ratio between the lesion’s values and the contra-lateral normal values, referred to as the rMTT, rTTP, rCBF, rCBV, rMD, and rMK.
Statistical Analysis.
Statistical analysis was performed using the Statistical Product and Service Solutions software (SPSS, Chicago, Ill). Medcalc and GraphPad Prism 8 (https://www.graphpad.com) software packages were used for graph rendering. All clinical and imaging metrics were compared between the good and poor prognosis groups. Student’s t-test or Mann-Whitney U test was used for continuous variables with a normal or non-normal distribution, and the Chi-square test was used for categorical variables. Continuous variables included age, NIHSS score, lesion size, rMTT, rTTP, rCBF, rCBV, rMD, and rMK. Categorical variables included gender, history of hypertension, diabetes, smoking, drinking, and previous stroke. Spearman’s correlations were determined between age, NIHSS score, imaging markers, and different prognoses. The chi-square test and Pearson’s contingency coefficient were determined between gender, all risk factors, and different prognoses. The ROC curve was used to compare the predictive efficacy of clinical and imaging metrics on the prognosis of the infarction, and the area under the curve (AUC) was calculated. P < 0.05 was considered as significant difference.
Ethical approval and consent to participate
The study protocol was approved by the Ethics Committee of Tianjin First Central Hospital, all participants gave their written informed consent.