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Diffusion-Weighted MRI Monitoring of Embolic Brain Stroke for COVID-19 Patients
Hamed Taheri1, Reza Moghareabed2, Maryam Farghadani3, Sheyda Lafz4, Hossein Taheri5
1 Nursing and Midwifery Department, Islamic Azad University of Isfahan (Khorasgan), Isfahan, Iran
2 Radiation-Oncology Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
3 Radiology Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
4 School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
5 Medical Physics Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| Date of Submission | 12-Nov-2021 |
| Date of Acceptance | 09-May-2022 |
| Date of Web Publication | 31-Aug-2023 |
Correspondence Address:
Sheyda Lafz
School of Medicine, Isfahan University of Medical Sciences, Isfahan
Iran
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/abr.abr_360_21
Background: Coronavirus disease (COVID-19) pandemic around the world has some adverse effects on the human body, and there is limited data about the impacts of this pandemic disease on embolic brain stroke.
Materials and Methods: Fifty-two COVID-19 patients with embolic brain stroke were included in this study. The COVID-19 patients were diagnosed according to their clinical findings. The patients underwent diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) values of different points of their brain were calculated using MRIcro software.
Results: The embolic strokes were mostly diagnosed in the medial temporal lobe for both COVID-19 and others. In addition, a combination of COVID-19 with other inflammations and infections was not diagnosed in the studied patients. The mean ADC values of the central region were significantly lower than other regions of the brain stroke for the COVID-19 and other patients. Moreover, the maximum and minimum ADC values of the central region for COVID-19 and other patients were significantly different compared to the other regions. Whereas, the mean and minimum ADC values of the brain's normal regions were not significantly different in the edge regions for both groups, while in the COVID-19 and other patients the maximum ADC value of the edge regions was considerably lower compared to the normal regions.
Conclusion: The embolic stroke of COVID-19 patients is likely to occur in the medial temporal lobe of the brain. Moreover, the ADC and relative ADC (rADC) values of embolic brain stroke in COVID-19 patients are not significantly different compared to others.
Keywords: ADC, brain stroke, COVID-19, DWI, MRI
How to cite this article:
Taheri H, Moghareabed R, Farghadani M, Lafz S, Taheri H. Diffusion-Weighted MRI Monitoring of Embolic Brain Stroke for COVID-19 Patients. Adv Biomed Res 2023;12:220 |
How to cite this URL:
Taheri H, Moghareabed R, Farghadani M, Lafz S, Taheri H. Diffusion-Weighted MRI Monitoring of Embolic Brain Stroke for COVID-19 Patients. Adv Biomed Res [serial online] 2023 [cited 2023 Sep 26];12:220. Available from: https://www.advbiores.net/text.asp?2023/12/1/220/384993 |
| Introduction | |  |
Brain stroke occurs when the blood supply to part of the brain is interrupted or reduced, caused to some parts of the brain cannot do their function properly due to damage and mortality of brain cells.[1] The lesion is commonly diagnosed using some modalities such as neurological examination, computerized tomography (CT) scan, and magnetic resonance imaging (MRI). Diffusion-weighted imaging (DWI) is one of the most common diagnostic methods that opened new horizons in diagnosing some brain lesions and malignancies. It plays a prominent role in evaluating multiple neurologic diseases such as brain stroke.[2],[3],[4],[5],[6],[7],[8] In this modality, the signal is based on the microscopic motion of the water molecules which depends on the thermal energy of tissues.[2],[3],[4],[5],[6],[7],[8] Therefore, the amount of water diffusivity of normal tissues and lesions could be different, due to their various temperatures as well as different thermal energies of water protons. Many studies have demonstrated that brain lesions may illustrate different apparent diffusion coefficient (ADC) maps, due to variations in the amount of their water molecule diffusivity.[9],[10],[11],[12] Brain consists of many structures which may have different anatomical and physiological features. It is considered that the physiological features may lead to different water diffusivity, and also different ADC values.[13],[14] In 2019, the coronavirus disease (COVID-19) disease emerged, and nowadays it is considered that the COVID-19 pandemic around the world has some unknown adverse effects on the human body. To the best of our knowledge, there is limited data about the impacts of this pandemic disease on embolic brain stroke. Therefore, this study was performed to evaluate the embolic brain stroke diffusion-weighted (DW) images and assess the changes of ADC values in different points of embolic brain stroke in the COVID-19 patients compared to other embolic brain strokes, with the hypothesis that different regions of the brain in the COVID-19 patients may have different ADC values on the DW MR images, and it could be instructive in clinical diagnosis of the mentioned disease.
| Materials and Methods | | |
Patients selection
This retrospective study was performed on 52 COVID-19 patients (34 male and 28 female), and 56 non-coronavirus disease (non-Covid) patients (35 male and 31 female) referred to the Kashani medical imaging clinic, who were suspected to have brain stroke according to their clinical findings. Furthermore, the COVID-19 patients were diagnosed based on their lung CT scan images and laboratory results including positive oropharynx or nasopharynx polymerase chain reaction (PCR). In addition, the patients who suffer from intracerebral hemorrhage (ICH) were excluded. Moreover, according to clinical data and image analysis, cerebral meningitis and encephalitis were not diagnosed in all the patients [Table 1].
MR Imaging
The MRI study was performed using a 1.5 Tesla Siemens Avento MRI scanner (Siemens, Germany). The DWI sequence included a multi-section single-shot spin echo-planar imaging (EPI) sequence with diffusion gradients, which were applied sequentially in all directions (X, Y, and Z). The diffusion sensitivity of b values was 1000 s/mm2. The slice thickness and inter-slice gap were 5 mm and 1 mm, respectively, and the TR/TE was 4400/110 ms. The field of view (FOV) was 200 mm, the matrix size was selected as 256 × 256 for all studied images, and also the total acquisition time for each DWI sequence was 80 s. The used acquisition gradient coils were located above the patient's brain according to the manufacturer of the applied MRI scanner.
Image analysis
Four regions of interest (ROIs) were drawn from central, near central, near edge, and also the edge of stroke areas in the ADC maps. The ADC values were calculated automatically using MRIcro software (were expressed in 10-3 mm2/s) according to the following formula (equation 1)[15],[16],[17],[18]:
(1) S/S0 = e –bD
In the above equation, the DW signal is denoted as S, the signal intensity without the diffusion weighting is S0, b is the diffusion sensitivity (b-value), and D stands for the diffusion coefficient (ADC value).
The relative ADC (rADC) values were given according to below equation 2[19]:
(2) rADC = (average ADC value in stroke regions/average ADC value in health regions)
Statistical analysis
Mean values and standard deviations (SD) of the ADC and rADC values were calculated, and the statistical significance and analysis of the differences among these values were evaluated using SPSS (version 16.0, Chicago, IL, USA) software. Wilcoxon test as a non-parametric version of paired samples T-test was applied to evaluate the results and a P value less than 0.05 was considered statistically significant.
| Results | | |
[Figure 1] illustrates the study flowchart, and [Figure 2] compares the mean ADC values of the different mentioned regions of the embolic stroke in the COVID-19 and non-Covid patients. [Table 2] and [Table 3] indicate the minimum, mean, and maximum ADC values of the stroke in non-COVID-19 and COVID-19 patients, respectively. These tables also show the rADC values of different regions of the lesion. According to our analysis, the embolic brain stroke was prone to occur in the medial temporal lobe of the brain in 83% of non-COVID-19 and 89% of COVID-19 patients. In this study, the combination of COVID-19 with other inflammations was not diagnosed for the mentioned embolic patients. | Figure 2: The mean ADC values of embolic brain stroke for COVID-19 (orange lines) and non-Covid patients (blue lines)
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 | Table 2: The ADC and rADC values of none COVID-19 embolic brain stroke patients. The values are expressed in 10-3 mm2/s
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 | Table 3: The ADC and rADC values of COVID-19 embolic brain stroke patients. The values are expressed in 10-3 mm2/s
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Results showed that the mean (± SD) ADC value for central regions of stroke was 20. 03 ± 0.24 for non-COVID-19 patients. [Table 2] also illustrates the maximum and minimum ADC values for central regions of non-COVID-19 patients were 21.05 and 18.37, respectively. The mean (± SD) ADC value for near central regions was 21.34 ± 1.78 as well [Table 2]. The maximum and minimum ADC value of near central regions was 23.65 and 19.27, respectively. The mean (± SD) ADC value of the near edges regions was 27.69 ± 2.87. Furthermore, the maximum and minimum ADC values for the near edge regions were 28.74 and 25.13, respectively [Table 2]. In addition, the mean (± SD) ADC value of edge regions was 31.46 ± 1.54 and the maximum and minimum ADC value of edge regions was 31.59 and 29.03, respectively. Moreover, for the rADC, the mean (± SD) for the central, near central, near edge, and also edge of stroke for non-COVID-19 patients was 0.52 ± 0.01, 0.54 ± 0.04, 0.71 ± 0.03, and 0.81 ± 0.01, respectively, in comparison with the central region [Table 2].
Whereas, for the COVID-19 embolic brain stroke patients, the mean (± SD) ADC value for central regions of stroke was 19. 07 ± 0.13. Also, the maximum and minimum ADC values for central regions of COVID-19 patients were 20.16 and 17.56, respectively. Furthermore, the mean (± SD) ADC value for near central regions was 20.42 ± 0.81. [Table 3] also demonstrates that the maximum and minimum ADC value of near central regions was 22.06 and 17.53, respectively. In addition, the mean (± SD) ADC value of the near edges regions was 26.58 ± 1.02. Based on the measured data of near edge regions in the COVID-19 patients, the maximum and minimum ADC values were 27.48 and 24.17, respectively [Table 3]. According to our data, the mean (±SD) ADC value of edge regions was 30.68 ± 1.23. Moreover, the maximum and minimum ADC value of edge regions was 29.07 and 28.56, respectively. [Table 3] also shows that the mean (± SD) rADC of the COVID-19, for the central, near central, near edge, and also edge of stroke was 0.50 ± 0.02, 0.53 ± 0.06, 0.69 ± 0.02, and 0.80 ± 0.08, respectively.
Based on our data, it was found that the mean (± SD) ADC value for the normal brain regions of non-COVID-19 and COVID-19 patients was 39.02 ± 2.03 and 38.21 ± 1.72, respectively.
| Discussion | | |
DWI and ADC map methods are one of the most commonly used modalities of MRI which is an instructive method to diagnose multiple neurologic diseases such as brain stroke.[13],[20],[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34],[35],[36],[37],[38],[39] In this method, the image intensity reflects the amount of water diffusion in the studied regions.[19] Many studies have discussed about the advantages of DWI and ADC maps for brain stroke, but data about the different values of ADC in different regions of embolic brain stroke among COVID-19 patients are scarce in the works of literature. Shen et al. have found that in brain-infracted regions, the ADC and rADC values may vary temporally and spatially which may be followed by progression of infarction and damaged tissue.[19] Therefore, the study was performed to evaluate the ADC and rADC values of different regions in brain stroke among the mentioned patients.
In this study, diagnosing the embolic brain stroke in the medial lateral lobe is in prospect for all patients, and there were no significant differences between the COVID-19 and non-Covid patients. Based on our findings for the embolic brain strokes in COVID-19 patients, evidence of the combination of COVID-19 with other inflammations and infections was not diagnosed. Therefore, it seems that COVID-19 may have an indirect role in the thromboembolic process for the mentioned studied patients. [Table 2] and [Table 3] indicate the ADC values of the different regions of brain stroke for the non-COVID-19 and COVID-19 patients. The tables also give the comparison of rADC values among the different studied regions. Based on our findings, the spatial distribution of ADC was different between the mentioned studied regions of the brain stroke for the COVID-19 and non-Covid patients. In addition, in this study, it was found that the rADC values of these stated regions were different.
Our data showed that, for the non-COVID-19 patients, the mean ADC values of the central region were significantly lower than the near central, near edges, and also edge regions of the brain stroke (p = 0.047, P = 0.039, and P = 0.035, respectively). For the brain strokes in COVID-19 patients, our data indicated similar results with non-Covid patients. The mean ADC values of the central region for the COVID-19 patients were considerably lower compared to other regions such as near central, near edges, and also the edge of the brain stroke (p = 0.035, P = 0.043 and P = 0.047, respectively). In addition, the maximum (p = 0.043, P = 0.037 and P = 0.031, respectively) and minimum (p = 0.048, P = 0.046 and P = 0.037, respectively) ADC values for central region of non-COVID-19 patients was considerably lower than the other discussed regions. Similarly, for the COVID-19 patients, the maximum (p = 0.048, P = 0.032 and P = 0.038, respectively) and minimum (p = 0.041, P = 0.037 and P = 0.043, respectively) ADC values of central region was significantly lower than the other regions. Also, the maximum, mean, and minimum ADC and rADC values of the edge region for COVID-19 and non-Covid patients were higher compared to other mentioned regions of brain stroke. In addition, as expected, the maximum, mean and minimum ADC values, and also the mean rADC value of the near central region for both COVID-19 and non-Covid patients was lower compared to the near edge and edge regions. The maximum ADC values of the edge regions were considerably lower than normal regions for COVID-19 and other stroke patients (p = 0.035, P = 0.038); however, the mean and minimum ADC values of the normal regions of the brain were not significantly different compared to edge regions for all the patients with brain stroke (p = 0.073 and P = 0.064, respectively).
These results were mainly due to higher water molecule diffusivity in the normal regions of the brain compared to other regions for all discussed patients. Moreover, it is known that thermal energy can considerably affect the kinetic energy and consequently water molecule movement.[7],[9],[10],[11] Therefore, the thermal energy of the mentioned regions of the brain may significantly affect the water molecule movement,[8],[10],[11],[12] and it is considered that the thermal energy of the central region may be lower than the other stated regions which may lead to lower water proton diffusivity in the central region compared to near, central and edge areas,[13],[14],[15],[16],[17],[18],[19],[20],[21] which is reflects the severity of the brain tissue damage in central region compared to the side areas. Moreover, it seems that water molecule movement of different region of stroke in COVID-19 patients is slightly lower compared to other stated strokes. In this study, the mentioned ADC values was measured in on the contralateral side to calculate the rADC values to decrease individual differences.
Based on our results, there were no significant differences in the ADC values among COVID-19 and non-Covid patients. In all studied patients with brain stroke, the central region has significantly lower ADC values compared to other stated regions, which reflects the increase of ADC spatial distribution from the central to the side regions. It is mostly due to lower water movement and consequently lower water diffusivity in central region cells in comparison with other regions. Furthermore, in all patients, the mean and minimum ADC values of normal regions were not significantly different compared to edge regions of the stroke.
The physical differences of the MR magnet systems may affect the result of this study. Therefore, further research using other samples and other MRI scanners is recommended.
| Conclusion | | |
In this paper, the DW-MR images and ADC and rADC values for different regions of embolic brain stroke for COVID-19 and non-Covid patients were evaluated.
Based on the results of this work, embolic stroke is likely to diagnose in the medial temporal lobe of the brain for all the patients with no significant differences among the ADC values of the ADC maps in DW images of brain stroke for COVID-19 and non-Covid patients. Moreover, in this study, it was found that not only do the central, near central, and near edge regions of brain stroke may have different ADC and rADC values, but also due to common diagnostic errors in differentiating edge regions of stroke and normal regions of the brain, it could be better to evaluate their ADC values as well.
Acknowledgements
The authors wish to thank the medical imaging center of Kashani hospital for their help in the completion of the article.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]
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