Magnetic Resonance Imaging in Cerebral Venous Thrombosis
Pramod Kumar R. Shah1*, Amol Gautam2, Siddhant Shailesh Chavan3, Ravindra Jarag4
1,2,3Department of Radiodiagnosis, Krishna Institute of Medical Sciences,
Krishna Vishwa Vidyapeeth Deemed to be University, Karad, Maharashtra, India- 415110.
4Department of Pharmacology, Bharati Vidyapeeth College of Pharmacy, Kolhapur – 416013.
*Corresponding Author E-mail: drpramod_shahkims@yahoo.com
ABSTRACT:
Cerebral venous thrombosis (CVT) is a category of stroke that occurs when blood clots form in dural sinuses cerebral veins or, resulting in inflammation and injury to brain tissue. Magnetic resonance imaging (MRI) is a valuable non-invasive tool for diagnosing and managing CVT, as it enables visualization of cerebral veins and sinuses and can differentiate CVT from similar conditions. MRI gives information on the location, severity, extent, and complications of thrombosis, including hemorrhage and brain edema. Advanced MRI sequences, such as diffusion-weighted imaging (DWI), can detect acute ischemic changes and differentiate between cytotoxic and vasogenic edema. This study intended to assess the effectiveness of conventional and advanced MRI techniques in diagnosing CVT in a group of 50 patients. MR venogram and other conventional MRI sequences were used to diagnose CVT in 96% patients, while contrast venography was used in 4% patients. The study was conducted over 18 months, and statistical analysis was performed on the data to assess the significance of the findings. The study found that the majority of patients experienced headaches, and the SSS (superior sagittal sinus) was the most commonly affected sinus. The thrombosis location was associated with parenchymal involvement in different regions. The age of the thrombus correlated with clinical presentation and imaging findings, and the presence of intraparenchymal hematoma in acute phase and hemorrhagic infarct in subacute phase and was significantly correlated. These findings can help guide timely and appropriate treatment for CVT.
KEYWORDS: Magnetic resonance imaging, diffusion-weighted imaging, vasogenic edema, hemorrhagic venous infract, heterointense.
INTRODUCTION:
CVT or Cerebral venous thrombosis is a type of stroke that has various causes and can result in diverse clinical manifestations. It occurs when a blood clot forms in one of the dural sinuses or cerebral veins, obstructing blood flow and leading to inflammation and injury to brain tissue. The incidence of CVT has been found to be higher than previously estimated, and its clinical features may resemble those of acute arterial stroke or mass lesions. The pathophysiology of CVT with associated venous stroke differs from that of arterial strokes.
While acute arterial strokes usually present with cytotoxic edema, which is due to the influx of water and sodium into brain cells, venous strokes are believed to involve vasogenic and interstitial edema due to venous congestion. Furthermore, venous thrombosis can cause decreased cerebral blood flow, impaired oxygen delivery, and increased intracranial pressure, leading to further damage to the brain tissue.
Magnetic resonance imaging (MRI) has emerged as a valuable tool in the diagnosis and management of CVT. It allows for non-invasive visualization of the cerebral veins and dural sinuses and can help distinguish CVT from other conditions that may present with similar symptoms1. MRI is the preferred imaging technique for diagnosing CVT because it can detect the clot and any associated complications, such as brain swelling or hemorrhage. The MRI scan can also reveal the extent of the clot and any damage that has occurred to the brain tissue. The images produced by MRI are high resolution, and the technique is particularly useful in identifying small clots and in distinguishing between CVT and other conditions that can cause similar symptoms.
MRI can also be used to monitor the progress of treatment for CVT. Repeat MRI scans can show whether the clot has dissolved, whether any new clots have formed, and whether the brain tissue is recovering from any damage caused by the initial clot. The information obtained from MRI can help guide the course of treatment and determine whether further interventions, such as anticoagulation therapy, are necessary. MRI can also provide information about the location, extent, and severity of the thrombosis, as well as the presence of associated complications such as hemorrhage or brain edema. Advanced MRI sequences, such as diffusion-weighted imaging (DWI)2,3, have been found to be particularly useful in the evaluation of CVT. DWI is a technique that uses the movement of water molecules to create images of the brain tissue, and can detect changes in water diffusion that occur in different types of edema. It has been shown to be more sensitive than conventional MRI in detecting acute ischemic changes and can help differentiate between cytotoxic and vasogenic edema, which can have implications for treatment.
Given the prominence of MRI in the diagnosis and management of CVT, there is a need to better understand its various applications and limitations. This study aims to examine the different facets of MRI technique in cerebral venous thrombosis, with a focus on the use of conventional and advanced imaging sequences and also evaluates the interobserver variability and diagnostic accuracy of the different MRI techniques.
MATERIAL AND METHODS:
A prospective observational study was carried out at the Department of Radio Diagnosis, Krishna Institute of Medical Sciences and Hospital, Karad, for 18 months, from October 2019 to March 2021. The study included 50 patients who were diagnosed with cerebral venous thrombosis (CVT) through conventional MRI, diffusion-weighted imaging, and MR venography. Among the 48 patients, MR venography and other conventional MR sequences confirmed the diagnosis. The remaining two patients underwent MR contrast venography using ClariscanTM 0.5 m mol/ml Wipro GE healthcare's 10 ml gadolinium-based contrast media. The study was conducted on a 1.5 T MRI unit Siemens Magnetom Avanto system with surface/body coils. Two b values with echo planar imaging were used to acquire diffusion-weighted images, while MR venography was performed using 2D Phase contrast technique in sagittal and coronal planes. The study included 28 females (56%) and 22 males (44%) between the ages of 19 and 71 years, with a mean age of 36.72±12.41 years. The age distribution was as follows: 40% of patients fell into the 21– 30 year age bracket, 26% into the 31- 40 year group, and 20% into the 41-50 year group. There was no significant difference in the distribution or mean age between genders, as determined by statistical analysis using Chi-square and t-tests. Continuous variables were represented by mean± SD, and categorical variables were represented by frequency. The normality of variables was assessed using the Shapiro-Wilk’s test, while the two-sample t-test and chi-square test were used to compare the mean between the groups and determine the association between two categorical variables, respectively. A p-value less than or equal to 0.05 was considered statistically significant.
RESULTS AND DISCUSSION:
The study enrolled a total of 50 participants aged between 19 and 71 years, with a mean age of 36.72±12.41 years. Females slightly outnumbered males, accounting for 56% (28 participants) of the sample, while males made up the remaining 44% (22 participants). The largest age group was the 21-30 year old category, comprising 40% of the participants, followed by the 31-40 year old group with 26%, and the 41-50 year old group with 20%. Although the most common age of presentation for males was 41-50 years, and for females, it was 21-30 years, statistical tests using Chi-square and t-tests indicated that there was no significant difference in age distribution or mean age between genders. According to the past history, 56% patients were idiopathic while 16% were postpartum and 10% were on OC pills, Fig. 1(A). Amongst the 50 patients, the major symptom was headache (76%) followed by Neurological defect (38%), seizure (26%) and vomiting (26%), Fig. 1(B). According to the distribution of sinuses, SSS and its combinations were highest (70%) followed by Transverse Sinus and its combination (42%), Fig. 1 (C) and (D).
Figure 1: Analysis of the profile of 50 patients subjected to MRI. (a) Distribution of the subjects by past history; (b) Distribution of patients by symptoms; and (d) Distribution of patients by sinuses involved in the study.
Figure 2: The detailed analysis of the MRI findings. (A) Distribution of the subjects T1, T2, Flair; (B) Distribution of subjects by MRI findings; (C) Distribution of the subjects by brain parenchymal leision; and (D) Discrepancy between thrombus age and presentation
The MRI findings are summarized in the Figure 2 (A and B). It was found that that 40% patients had Hemorrhagic venous Infract and 38% had non hemorrhagic infract, Figure 2(C).
Types of Presentation:
The presentation had 3 categories viz., acute, chronic and subacute. The parameters age, gender, Non hemorrhagic infract and SAH did not have any signification association with the presentation while days of presentation, Hemorrhagic venous infract, IPH and normal had significant association with the type of presentation, Figure 3-8 and Table 1.
Figure 3: Images of the patient's brain
The imaging findings of the patient's brain indicated a region, Fig. 3(A), in the right parieto-temporal area with altered signal intensity, measuring approximately 6.5 x 3.0 x 2.6 cm, that appears hyperintense on T2WI/FLAIR and hyperintense on T1WI, Fig. 3(B). There is corresponding blooming on SWI, Fig. 3(C), which suggests an intraparenchymal hematoma in the acute to subacute stage with surrounding edema. Additionally, there was a loss of flow void in the superior sagittal sinus, with intraluminal hypointensity on T2W, Fig. 3(D) and hyperintensity on T1W, Fig. 3(E). Finally, there is superior sagittal sinus thrombosis in the (F) 2D PC MIP image, with the right transverse sinus, jugular bulb, and sigmoid sinus appearing thinned out.
The MRI images of brain revealed, Fig. 4(A), TIWI has hypointense areas in both thalami, that are heterogeneously hyperintense on FLAIR, Fig. 4(B), with areas SW images having areas of blooming Fig. 4(C). Additionally, the affected areas were hyperintense on DWI, Fig. 4(D), and showed analogous low ADC values, Fig. 4(E), indicating an acute hemorrhagic infarct. Furthermore, the Fig. 4 (FandG) (MIP sequences) 2D PC MR Venogram showed thrombosis in the internal cerebral veins, SS (Straight sinus), and left transverse sinus, with fractional thrombus in the proximal 1/3rd of the transverse sinus in the right. The MRI images also showed huge areas with adjacent edema seeming hyperintense on Fig. 4(B) T2WI/FLAIR, with Fig. 4(C) blooming areas on hemo sequences, and Fig. 4(D) diffusion constraint in the patchy areas involving cortex and subcortical white matter of bilateral frontal lobes, indicating an acute hemorrhagic venous infarct.
Figure 4: MRI images of brain
|
|
Types of Presentations |
Significances |
|||
|
Chronic (n=03) |
Acute (n= 15) |
Subacute (n = 32) |
|||
|
Age (in years) |
≤ 20 |
0 (0%) |
0 (0%) |
1 (3.13%) |
0.46MC |
|
21-30 |
0 (0%) |
9 (60%) |
11 (34.38%) |
||
|
31-40 |
1 (33.33%) |
2 (13.33%) |
10 (31.25%) |
||
|
41-50 |
2 (66.67%) |
3 (20%) |
5 (15.63%) |
||
|
51-60 |
0 (0%) |
0 (0%) |
3 (9.38%) |
||
|
61-70 |
0 (0%) |
1 (6.67%) |
1 (3.13%) |
||
|
≥ 71 |
0 (0%) |
0 (0%) |
1 (3.13%) |
||
|
Age (years) |
43.33±4.93 |
35.2±12.71 |
36.81±12.79 |
- |
|
|
Gender |
Female |
2 (66.67%) |
6 (40%) |
20 (62.5%) |
0.405MC |
|
Male |
1 (33.33%) |
9 (60%) |
12 (37.5%) |
||
|
Days of presentation |
32±2.65 |
1.53±0.52 |
7.94±4.07 |
- |
|
|
T1 |
Hetero Intense |
0 (0%) |
1 (6.67%) |
17 (53.13%) |
0.014*MC |
|
Hyper Intense |
0 (0%) |
0 (0%) |
3 (9.38%) |
||
|
Hypo Intense |
2 (66.67%) |
6 (40%) |
9 (28.13%) |
||
|
Iso Intense |
1 (33.33%) |
8 (53.33%) |
3 (9.38%) |
||
|
T2 |
Hetero Intense |
0 (0%) |
1 (6.67%) |
17 (53.13%) |
0.014*MC |
|
Hyper Intense |
1 (33.33%) |
9 (60%) |
13 (40.63%) |
||
|
Hypo Intense |
1 (33.33%) |
3 (20%) |
0 (0%) |
||
|
Iso Intense |
1 (33.33%) |
2 (13.33%) |
2 (6.25%) |
||
|
Flair |
Hetero Intense |
(0%) |
1 (6.67%) |
17 (53.13%) |
0.014*MC |
|
Hyper Intense |
1 (33.33%) |
9 (60%) |
13 (40.63%) |
||
|
Hypo Intense |
1 (33.33%) |
3 (20%) |
0 (0%) |
||
|
Iso Intense |
1 (33.33%) |
2 (13.33%) |
2 (6.25%) |
||
|
Hemorrhagic venous Infarct |
Negative |
0 (0%) |
13 (86.67%) |
14 (43.75%) |
0.007*MC |
|
Positive |
0 (0%) |
2 (13.33%) |
18 (56.25%) |
||
|
Non hemorrhagic infarct |
Negative |
3 (100%) |
8 (53.33%) |
20 (62.5%) |
0.334MC |
|
Positive |
0 (0%) |
7 (46.67%) |
12 (37.5%) |
||
|
IPH |
Negative |
2 (66.67%) |
10 (66.67%) |
30 (93.75%) |
0.046*MC |
|
Positive |
1 (33.33%) |
5 (33.33%) |
2 (6.25%) |
||
|
SAH |
Negative |
3 (100%) |
15 (100%) |
31 (96.88%) |
1MC |
|
Positive |
0 (0%) |
0 (0%) |
1 (3.13%) |
||
|
Normal |
Negative |
1 (33.33%) |
15 (100%) |
32 (100%) |
0.000*MC |
|
Positive |
2 (66.67%) |
0 (0%) |
0 (0%) |
||
MC: Chi-square test’s Monte-Carlo’s simulation
Figure 5: The MR venogram (MIP sequences)
Figure 6: MRI images of brain
Figure 7: MRI images of brain
Figure 8: MRI images of brain
The MR venogram (MIP sequences), Fig. 5(A), shows acute thrombosis, with the anterior 2/3 of the SSS, superior sagittal sinus and its draining cortical veins presenting no flow-related enhancement and an isointense sign on T1W and a hypointense sign on T2W/FLAIR sequences. Additionally, there are huge areas with adjacent edema that appear hyper intense on T2WI/FLAIR, Fig. 5(B) and hemo sequences having areas of blooming, Fig. 5 (C), as well as sporadic areas of diffusion constraint involving the cortex and subcortical white matter of bilateral frontal lobes, indicating an acute hemorrhagic venous infarct.
The MRI images of brain show a focal area in the left frontal lobe with adjacent edema that appears hyperintense on T2WI/FLAIR Fig. 6(B) and shows hemo having areas of blooming sequences, Fig. 6(C), indicating a venous infarct that is acute hemorrhagic. The (MIP sequences) 2D PC MR Venogram, Fig. 6(A), reveals a thrombosis in the frontal 2/3rd of the SSS, superior sagittal sinus, which does not show flow related enhancement. Linear areas of blooming on hemo, Fig. 6(C), sequences are also visible, indicating a subarachnoid hemorrhage in the precentral and inferior frontal gyri on the left side.
The image findings suggest that there is a presence of acute non-hemorrhagic infarct in the left corona radiata, centrum semiovale, thalamus, gangliocapsular region and splenium of corpus callosum as there is hyperintensity on T2WI/FLAIR (C) and hypointensity on T1WI (D) with corresponding area of hyperintensity on Diffusion weighted images (A) and hypointense on ADC (B) indicating Diffusion restriction. There is no evidence of blooming on hemo sequences (F). Additionally, there is subacute thrombus noted within the SSS, superior sagittal sinus, both straight sinus and transverse sinuses, as indicated by heterointense predominantly hyperintense signal on T2 (C) and T1W (D) with the mentioned sinuses grossly thinned out on MIP image (E). Furthermore, cortical veins are increased in number-collaterals secondary to thrombosis.
Area of transformed signal intensity (~ 3.1x 2.0x 2.8 cm, volume ~ 33 – 35 cc) is seen in the right parietal lobe. It appears iso to hetero intense on T1W, Fig. 8(A), with peripheral hyper intensity, hetero intense predominantly hypointense on T2W, Fig. 8(B), with areas of diffusion restriction, Fig. 8(C); showing blooming on HEMO, Fig. 8(D), and hyperintensity on PHASE with surrounding edema suggesting an intraparenchymal hematoma. Additionally, there is harm of flow void of the SSS, superior sagittal sinus with intraluminal hyperintensity on T1W and T2W, Fig. 8(D) and hyperintensity on T1W, Fig. 8(E) indicating subacute thrombosis. The MR venogram – MIP, Fig. 8(FandG) shows the lack of flow void in the frontal part of the SSS with reduced caliber in its posterior segment, as well as in posterior draining cortical veins. Multiple venous collaterals are noted.
Discrepancy between Thrombus Age and Presentation:
In this study, it was found that in 90% of cases, the clot age corresponded with the clinical presentation of patient at the time of imaging. However, in 10% of cases, we observed that although patients presented in the acute phase, the clot signal on conventional sequences (T1W, T2W and FLAIR) appeared consistent with the subacute phase, Figure 2 (D). CVT is a category of stroke that occurs when veins in the brain are blocked. It can be challenging to diagnose because its symptoms are diverse and not specific, but MRI and MR Venography are effective tools for identifying it. In a study involving 50 patients aged 19 to 71; the most repeatedly affected was age group of 21-30 years old, with a slight female preponderance. The most common presentation was subacute, within 2 to 30 days of the onset of symptoms, and the most frequent symptom was a headache. Patients were classified rendering to the onset of signs: those who presented within two days were considered acute, those within two to 30 days were categorized as subacute, and those over 30 days were classified as chronic.4
The study revealed that there are various risk factors that may be associated with cerebral venous thrombosis (CVT). About 56% of cases did not have a definite cause of CVT despite extensive history. This finding was higher than the previous study by Gates et al. indicating the importance of close follow-up of patients5. Peripartum thrombosis was observed in 16% of cases and may be related to hypercoagulable states. The use of oral contraceptive pills (OCP) for 6 to 14 months was observed in 10% of cases and was found to have a prothrombotic effect6. According to Martinelli et al., women of younger age groups who were using OCP had an increased risk of CVT7. Smoking history was present in 8% of cases, and trauma was seen in 4% of cases, with closed head injury and depressed skull fracture being the major factors. A study conducted by Miller et al. reported that cerebral venous sinus involvement was observed in 11% of 400 cases of depressed skull fractures, which can lead to the disruption of normal flow, increasing intracranial pressure and the potential development of CVT8. The most common symptoms observed in cases of CVT were found to be headache (76%), followed by focal neurological deficits (38%), seizures, and vomiting (26%)9. These symptoms were reported to be nonspecific and can result in significant brain involvement or be well-tolerated, depending on the availability of collateral venous pathways. In another study by Karthikeyen et al., it was found that headache was the most common presenting symptom, typically unilateral, while focal neurological deficits, seizures, impairment of level of consciousness, and papilledema occurred in one-third to three-quarters of cases10.
The involvement of venous sinus and abnormalities of cerebral parenchyma correlation:
The study revealed that the involvement of multiple segments of dural venous sinuses was observed in most patients with CVT. The superior sagittal sinus was found to be the most commonly affected sinus (70%), followed by the transverse sinus (42%) and sigmoid sinus (22%). In addition, the study found that the involvement of these sinuses was related with parenchymal involvement in the ipsilateral lobes. These findings are consistent with previous studies that have shown similar results regarding the predilection for the involvement of these sinuses in CVT.
Furthermore, the study revealed that the deep venous system was affected in only a small percentage of cases (6%), and the thalami and deep periventricular regions were the most commonly affected areas. The study also indicated that isolated cortical venous thrombosis was an extremely rare entity with imaging literature having less than 20 cases reported and was always associated with superior sagittal sinus (SSS) thrombosis11 -13. This finding is particularly significant as isolated cortical venous thrombosis is sometimes difficult to diagnose and can have severe consequences if left untreated. Overall, the study highlights the significance of a careful evaluation of the extent and location of venous sinus involvement in CVT as it can provide crucial information regarding the potential for parenchymal involvement and the need for close monitoring and treatment.
Kon Chu et al, found that conventional MR sequences such as T1W, T2W, and FLAIR were effective in detecting CVT in the majority of cases, and the use of diffusion weighted imaging (DWI) was not necessary for direct visualization of clots within cerebral sinuses18. Additionally, the study reported that clinical presentation was typically consistent with clot age, and that venous thrombosis was definite through 2D Phase Contrast MR Venogram by both MIP images and source in most cases. However, contrast MR venography was required in two cases for an accurate diagnosis. The study by Favroleetal suggests that conventional MR sequences are useful for identifying CVT and that DWI may not be necessary in all cases20. This finding is consistent with previous research, which has shown that conventional MR sequences are highly sensitive for detecting CVT. The study also highlights the importance of contrast venography in cases where 2D Phase Contrast MR Venogram is not sufficient for accurate diagnosis. Overall, the outcomes of this study suggest that MRI, particularly conventional MR sequences and contrast venography, is a useful tool for diagnosing CVT. However, the study also highlights the need for caution in interpreting MRI results, as not all cases of CVT may be visible on MRI, and other diagnostic tools may be necessary in some cases.
According to the results of our study, all cases of cerebral venous infarction that showed hyperintensity on diffusion-weighted images also presented T2 signal changes. It should be noted that the absence of hyperacute imaging may have prevented us from detecting diffusion restriction without T2 hyperintensity. Additionally, the different time intervals between disease onset and DWI may have been influenced by the diverse clinical manifestations of CVT, leading to variability and non-homogeneity in our findings.
CONCLUSIONS:
Our research presents a thorough assessment of various MRI techniques that can be employed to diagnose and manage cerebral venous thrombosis (CVT). The results of our study have significant implications for the clinical management of CVT, as they can aid in selecting the appropriate imaging methods and treatment approaches for patients. Additionally, our study aims to enhance our comprehension of the pathophysiology of CVT and the role of MRI in its diagnosis and management. It is important to note that CVT is a complex condition with distinct pathophysiological features from arterial strokes, and the diverse clinical manifestations of CVT can make diagnosis challenging. MRI has emerged as a valuable tool in the diagnosis and management of CVT, with advanced sequences such as DWI providing increased sensitivity and specificity in detecting acute changes. Our study findings indicate that the majority of patients with CVT present with headache, followed by focal neurological deficits, seizures, and vomiting. The superior sagittal sinus was identified as the most commonly affected sinus, followed by the transverse and sigmoid sinuses. Furthermore, depending on the location of the thrombosis, we observed specific regions of the brain with parenchymal involvement. Moreover, we observed that the age of the thrombus was consistent with the clinical presentation and imaging findings. Additionally, the presence of hemorrhagic infarct in the subacute phase and intraparenchymal hematoma in the acute phase showed significant correlation. These results have important implications for the diagnosis and management of CVT. It emphasizes the significance of identifying the clinical and radiological characteristics of CVT to ensure prompt and appropriate treatment.
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Received on 16.04.2023 Modified on 22.05.2023
Accepted on 19.06.2023 © RJPT All right reserved
Research J. Pharm. and Tech 2023; 16(6):2955-2962.
DOI: 10.52711/0974-360X.2023.00488