Imaging Characteristics of Venous Parenchymal Abnormalities

Poststroke action slowing increases with task complexity and is linked to broader brain recruitment

Despite its high prevalence, the mechanisms of slowing in stroke remain surprisingly poorly understood. Our objectives were (1) to determine the profile of slowing as a function of test complexity and (2) to examine the relationship between this complexity effect, test sensitivity and the recruitment of brain areas. The study focused on the 371 stroke patients and 581 controls of the GRECogVASC study assessed with eight time-limited tests: finger tapping, simple reaction time, line cancellation, Trail Making Test parts A and B, coding, and semantic and phonemic fluency tests. Action speed of patients was slower than that of controls (p = .0001); slowing worsened with test complexity (p = .0001) by 7.7% at each step of increasing complexity. The highest test sensitivity was observed (p = .0001) for more complex tests. The number of lesioned voxels associated with action speed increased with test complexity. The sensitivity of the tests roughly paralleled (p = .007) the volume of recruited brain areas. The individual slopes of action duration with test complexity correlated with the volume of lesion (p = .002), white matter hyperintensities (p = .0001) and parenchymal brain fraction (p = .0001). The effect of stroke on slowing is due both to small slowing on simple tests and to a general slowing of processing speed. The test sensitivity reflects the size of recruited brain network and its proportional vulnerability to lesion. In addition to their clinical implications, these results shed light on the organization of the systems that optimize action speed in humans.

Post-stroke outcome prediction based on lesion-derived features

Stroke-induced deficits result from both focal structural damage and widespread network disruption. This study investigated whether simulated measures of network disruption, derived from structural lesions, could predict functional impairments in stroke patients. We extracted four lesion-derived feature sets: lesion masks, probabilistic structural disconnection maps (pSDMs), structural and indirectly estimated functional connectivity strengths between brain regions, and topological properties of functional and structural brain networks to predict motor, executive, and processing speed deficits in 340 S patients, employing PCA-based ridge regression with leave-one-out cross validation. The findings revealed that both structural disconnection map patterns and lesion masks were strong predictors of functional deficits. Lesion masks exhibited superior predictive performance relative to unthresholded pSDMs. Furthermore, applying a probability threshold to the pSDMs - retaining only disconnections present in a sufficient proportion of healthy subjects - significantly improved predictive performance. For motor deficits, thresholded SDMs (tSDMs) with thresholds of 0.9 and 0.5 produced the highest R2 values, 0.95 for left motor deficits and 0.69 for right motor deficits, respectively. In the case of executive function and processing speed, the highest R2 values were 0.58 and 0.64, achieved with tSDM thresholds of 0.3 and 0.5, respectively. Connectome-based features exhibited lower R2 values, with structural connection strength alterations showing stronger associations with post-stroke scores compared to changes in functional connectivity. Nodal parameters (degree and clustering coefficient) had lower explanatory power than the SDM features and lesion masks. Our findings underscore the effectiveness of lesion masks and thresholded SDMs in predicting post-stroke deficits. This study contributes to the growing body of evidence supporting the reliability of simulated structural networks as a complementary approach to lesion patterns and structural disconnection in predicting post-stroke outcomes.

Effect of cerebral sinus venous thrombosis and its location on cerebral blood flow: a [15O]water PET study in acute stroke patients compared to healthy volunteers

BACKGROUND

Symptoms in acute cerebral sinus venous thrombosis (CSVT) are highly variable, ranging from headaches to fatal stroke, and the basis for this high inter-individual variability is poorly understood. The present study aimed to assess whether acute CSVT significantly alters regional cerebral blood flow (CBF), if findings differ from CBF patterns know from large-artery occlusion in stroke, and whether the pattern of CBF alterations depends on clot location. Therefore, we retrospectively analyzed 12 patients with acute CSVT 10.6 ± 4.6 days after symptom onset and ten healthy volunteers who underwent [15O]water PET (two scans each, 300 ± 14 MBq [15O]water). Static image datasets (15-75 s after injection; normalized to cerebellum) reflecting relative CBF (rCBF) were analyzed using voxel- and region-of-interest-based analysis (AAL3-atlas). We mirrored datasets of patients with left-sided CSVT to harmonize the affected hemisphere.

RESULTS

Seven and five patients showed right- and left-sided CSVT, respectively. The superior sagittal sinus (SSS) was involved in 8/12 patients. CSVT patients had extensive rCBF deficits in the voxel-based analysis with accentuation in the right (ipsilateral) frontal cortex and caudate nucleus compared to controls, which were most pronounced in cortical areas in those with involvement of the SSS (8/12), and in subcortical areas in those without involvement of the SSS (4/12; p < 0.05, false discovery rate corrected). ROI-analysis demonstrated significant frontal (p = 0.01) and caudate nucleus (p = 0.008) rCBF deficits driven by patients with and without SSS occlusion, respectively.

CONCLUSIONS

[15O]water PET was able to visualize characteristic patterns of impaired rCBF, which were different from intracranial large-artery occlusion in acute ischemic stroke, and exhibited substantial rCBF alterations depending on the involvement of the SSS. Our findings provide novel insights into the effects of disturbed venous drainage on CBF in acute CSVT, which may aid in understanding the pathophysiology, and guide future therapy of acute CSVT.

Neuroimaging determinants of cognitive impairment in the memory clinic: how important is the vascular burden?

While neurodegenerative and vascular neurocognitive disorder (NCD) often co-occur, the contribution of vascular lesions, especially stroke lesions identified on MRI, to global cognition in a real-life memory clinic population remains unclear. The main objective of this retrospective study was to determine NCD neuroimaging correlates: the GM atrophy pattern and vascular lesions (especially stroke lesion localization by voxel-based lesion-symptom mapping, VLSM) in a memory clinic. We included 336 patients with mild or major NCD who underwent cerebral MRI and a neuropsychological assessment. The GM atrophy pattern (obtained by voxel-based morphometry, VBM) and the stroke lesion localization (obtained by VLSM) associated with G5 z-score (a global cognitive score), were included as independent variables with other neuroimaging and clinical indices in a stepwise linear regression model. The mean age was 70.3 years and the mean MMSE score 21.3. On MRI, 75 patients had at least one stroke lesion. The G 5 z-score was associated with GM density in the pattern selected by the VBM analysis (R2 variation = 0.166, p < 0.001) and the presence of a stroke lesion in the region selected by the VSLM analysis (mainly in the right frontal region; R2 variation = 0.018, p = 0.008). The interaction between the two factors was insignificant (p = 0.374). In conclusion, in this first study combining VBM and VLSM analysis in a memory clinic, global cognition was associated with a specific GM atrophy pattern and the presence of a stroke lesion mainly in the right frontal region.

Cortical vein involvement and its influence in a cohort of adolescents with cerebral venous thrombosis

BACKGROUND AND PURPOSE

Cortical vein thrombosis (CVT) is a rare form of cerebral venous sinus thrombosis (CVST) in adolescent patients that has received little attention. We aimed to analyze the clinical and radiological features of adolescents with CVST and investigate the effects of CVT involvement.

METHODS

Patients aged ≥ 10 to ≤ 18 years and diagnosed with CVST were identified at Xuanwu Hospital, Capital Medical University between January 2015 and August 2022 and divided into two groups according to the presence or absence of cortical vein involvement. Additionally, the patients were also categorized based on their sex. Clinical features, radiological characteristics, and 12-month follow-up outcomes were compared between the two groups.

RESULTS

Fifty-three adolescents, including 21 with CVT, were included (mean age: 15.2 ± 1.8 years; females, 54.7%). The CVT group was more likely to experience seizures (P = 0.028) and deterioration (28.6% vs. 6.2%, P = 0.047) during hospitalization than the non-CVT group. Poor short-term outcomes, based on the modified Rankin Scale (mRS) score at discharge, were more common in adolescents with CVT (P = 0.007). The proportions of patients showing edema (42.9% vs. 6.2%, P = 0.004) and mass effect (P = 0.015) were significantly higher in the CVT group. Recanalization was observed in 61.9% and 82.1% of the patients in the CVT and non-CVT groups, respectively, during the first imaging review (median, 22 days). After a 12-month follow-up, female adolescents had more frequent resident secondary headaches than male adolescents (52.9% vs. 12.5%; P = 0.014).

CONCLUSIONS

Cortical vein involvement in adolescents with CVST was associated with a higher risk of epilepsy at presentation, deterioration during hospitalization, edema, and mass effect on acute imaging. Moreover, cortical vein involvement may lead to worse short-term outcomes. Sex differences require consideration in etiological analyses and prolonged follow-ups.

Functional architecture of executive processes: Evidence from verbal fluency and lesion mapping in stroke patients

The functional organization and related anatomy of executive functions are still largely unknown and were examined in the present study using a verbal fluency task. The objective of this study was to determine the cognitive architecture of a fluency task and related voxelwise anatomy in the GRECogVASC cohort and fMRI based meta-analytical data. First, we proposed a model of verbal fluency in which two control processes, lexico-semantic strategic search process and attention process, interact with semantic and lexico-phonological output processes. This model was assessed by testing 404 patients and 775 controls for semantic and letter fluency, naming, and processing speed (Trail Making test part A). Regression (R² = .276 and .3, P = .0001, both) and structural equation modeling (CFI: .88, RMSEA: .2, SRMR: .1) analyses supported this model. Second, voxelwise lesion-symptom mapping and disconnectome analyses demonstrated fluency to be associated with left lesions of the pars opercularis, lenticular nucleus, insula, temporopolar region, and a large number of tracts. In addition, a single dissociation showed specific association of letter fluency with the pars triangularis of F3. Disconnectome mapping showed the additional role of disconnection of left frontal gyri and thalamus. By contrast, these analyses did not identify voxels specifically associated with lexico-phonological search processes. Third, meta-analytic fMRI data (based on 72 studies) strikingly matched all structures identified by the lesion approach. These results support our modeling of the functional architecture of verbal fluency based on two control processes (strategic search and attention) operating on semantic and lexico-phonologic output processes. Multivariate analysis supports the prominent role of the temporopolar area (BA 38) in semantic fluency and the F3 triangularis area (BA 45) in letter fluency. Finally, the lack of voxels specifically dedicated to strategic search processes could be due to a distributed organization of executive functions warranting further studies.

Poststroke action slowing: Motor and attentional impairments and their imaging determinants. Evidence from lesion-symptom mapping, disconnection and fMRI activation studies

BACKGROUND AND OBJECTIVES

Although action slowing is the main cognitive impairment in stroke survivors, its mechanisms and determinants are still poorly understood. The objectives of the present study were to determine the mechanisms of post-stroke action slowing (using validated, highly specific simple reaction time (SRT) and tapping tests) and identify its imaging determinants (using multivariate lesion-symptom mapping (mLSM)).

METHODS

Action speed in the GRECogVASC cohort was assessed using finger tapping and SRT tests performed with both hands and analyzed using previously validated indices. Imaging determinants were identified using validated mLSM analyses and disconnection analysis and compared to those of an fMRI activation meta-analytic database.

RESULTS

Both the tapping time and SRT were 10.7% slower for the 394 patients (p = 0.0001) than for the 786 controls, without a group × test interaction (p = 0.2). The intra-individual distribution curve was characterized by a rightward shift with an unaltered attentional peak. The mLSM analyses showed tapping to be associated with lesions in the frontostriatal tract (p = 0.0007). The SRT was associated with lesions in the frontostriatal tract (p = 0.04) and the orbital part of F3 (p = 0.0001). The SRT-tapping index was associated with lesions in the orbital part of F3 (p = 0.0001). All lesions were located in the right hemisphere only and were responsible for the disconnection of several structures involved in motor preparation, initiation, and speed. A comparison with fMRI activation meta-analytic data highlighted mostly the same regions, including the orbital part of F3, the ventral and dorsal parts of F1, and the premotor and cingulate regions in the right hemisphere.

DISCUSSION

Our results confirm the marked impairment of action speed in stroke and show that the primary mechanism is motor slowing and that it is related to lesions in the right frontostriatal tract. A deficit in sustained alertness accounted for action slowing in the subgroup with lesions in the right orbital part of F3. Our SRT and mLSM results were in accordance with the fMRI activation data. Thus, stroke induces slowing in the broad network associated with SRT tasks by disrupting the frontostriatal tract and, to a lesser extent, other sites involved in attention.

Parenchymal Insults in Abuse—A Potential Key to Diagnosis

Subdural hemorrhage is a key imaging finding in cases of abusive head trauma and one that many radiologists and radiology trainees become familiar with during their years of training. Although it may prove to be a marker of trauma in a young child or infant that presents without a history of injury, the parenchymal insults in these young patients more often lead to the debilitating and sometimes devastating outcomes observed in this young population. It is important to recognize these patterns of parenchymal injuries and how they may differ from the imaging findings in other cases of traumatic injury in young children. In addition, these parenchymal insults may serve as another significant, distinguishing feature when making the medical diagnosis of abusive head injury while still considering alternative diagnoses, including accidental injury. Therefore, as radiologists, we must strive to look beyond the potential cranial injury or subdural hemorrhage for the sometimes more subtle but significant parenchymal insults in abuse.

A Case-Based Review of Cerebral Venous Infarcts With Perfusion Imaging and Comparison to Arterial Ischemic Stroke

Cerebral venous thrombosis (CVT) and cerebral venous infarcts (CVI) are diagnostic dilemmas secondary to their rarity, non-specific symptomatology at presentation, and variable imaging features. Despite its relatively infrequence, CVT is particularly prevalent in the younger adult population and is a potentially life-threatening disease with devastating neurological complications if not addressed in a timely manner. However, when treated promptly, CVT has the potential for a more reversible course and favorable prognosis than arterial ischemic strokes (AIS). The pathophysiology of CVI is distinct from that of AIS and is closely related to its potentially reversible nature. Familiarity with the conventional and variant venous anatomy, as well as the temporal evolution of imaging findings, is crucial in establishing diagnostic confidence. The use of MR perfusion imaging (MRP) and arterial spin-labeling (ASL) can potentially aid in the diagnosis of CVT/CVI via characterization of cerebral blood flow. The presence and extent of a cerebral perfusion deficit on either CT or MRI may play a role in clinical outcomes for patients with CVT, although future larger studies must be performed. This review presents a case-based overview focusing on the classic imaging characteristics of CVT and CVI in conjunction with bolus MRP and ASL findings in the adult population.

Identifying Biomarkers Associated with Venous Infarction in Acute/Subacute Cerebral Venous Thrombosis

Among cerebral venous thrombosis (CVT) patients, those with venous infarction have more severe clinical presentations and worse outcomes. Identifying biomarkers associated with venous infarction in CVT may help understand the pathogenesis and provide potentially useful therapeutic markers. Fifty-two CVT patients were prospectively recruited and divided into three groups: acute/subacute CVT with venous infarction (ASVI, n=30), without venous infarction (ASOVI, n=13), and chronic CVT (n=9). Blood brain barrier (BBB) permeability-related proteins, including claudin-5, occludin, matrix metalloproteinase-9, glial fibrillary acidic protein, and S100B, and inflammation-related factor high-sensitivity C-reactive protein (hs-CRP), were tested in serum and/or cerebrospinal fluid upon admission. We compared these biomarkers between the three groups and investigated their associations with venous infarction and clinical symptom severity in acute/subacute CVT patients on admission using the NIH Stroke Scale (NIHSS). Serum hs-CRP was significantly higher in acute/subacute CVT patients than chronic CVT patients. For acute/subacute CVT patients, levels were significantly higher in the ASVI group than the ASOVI group for serum claudin-5 (medians 2.80 vs. 2.50 mg/I, respectively, P = 0.039) and hs-CRP (medians 17.25 vs. 2.27 mg/l, respectively, P = 0.003). Both these biomarkers, analyzed as categorical or continuous variables, were also significantly associated with venous infarction in acute/subacute CVT patients after logistic regression analysis. Additionally, hs-CRP was positively correlated with the NIHSS (r = 0.710, P < 0.001) on admission in acute/subacute CVT patients. In CVT patients, venous infarction was associated with BBB disruption and potentially inflammation. Hs-CRP might serve as a biomarker reflecting the clinical severity of CVT in the acute/subacute stages.

Labbé vein thrombosis

PURPOSE

Evaluate the prevalence of Labbé vein thrombosis (LVT) and its liability for the lesions observed in the case of associated ipsilateral transverse sinus thrombosis (TST).

METHODS

MRI findings of 58 consecutive patients (≥ 18 years) with acute LVT and TST (group 1) were compared with those of 149 patients with acute TST-no LVT (group 2) observed during the same period.

RESULTS

The prevalence of LVT was 15.2%. Group 1: TST extended to sigmoid sinus in 94.8%, resulting in complete sinuses occlusion. Any lesion was observed in 81% within LV territory: swelling (n = 5, 8.6%), edema (n = 9; 15.5%), non-hemorrhagic Infarct (n = 1; 1.7%), multiple temporal lobe hemorrhages (n = 31; 53.5%), temporal lobe hematoma (n = 13; 22.4%), and pericerebral hemorrhages (n = 28; 50%). The hemorrhagic lesions were not related to dominant TST or to extensive venous thrombosis. There was a prevalence of left TST- LVT (n = 32; 55.2%) and a higher prevalence of hemorrhagic lesions in this subset (59.4%). Risk factors were also associated (p = 0.03). Group 2: the TST resulted in an occlusion of the TS: (i) complete (n = 16; 10.7%); (ii) incomplete (n = 97; 82.8%); and (iii) segmental, involving the TS before (n = 32; 21.5%) or after (n = 10; 6.7%) LV ending within the TS. No parenchymal/pericerebral lesions were associated.

CONCLUSION

This study shows a strong association between the following: (i) the extent of thrombosis in the TS and the presence of LVT (p < 0.0001), (ii) the concomitance of LVT-TST and the presence of lesions in the LV territory and at the temporo-frontal convexity, (iii) risk factors and group 1 (p = 0.03).

Features of intracranial hemorrhage in cerebral venous thrombosis

BACKGROUND

Cerebral venous thrombosis (CVT) is associated with intracranial hemorrhage.

AIM

To identify clinical and imaging features of CVT-associated intracranial hemorrhage. We hypothesized that higher clot burden would be associated with a higher risk of intracranial hemorrhage.

METHODS

We performed a retrospective analysis of an international, multicenter cohort of patients with confirmed cerebral venous thrombosis who underwent computed tomography within 2 weeks of symptom onset. Clinical and imaging features were compared between patients with and without intracranial hemorrhage. Clot burden was assessed by counting the number of thrombosed venous sinuses and veins on confirmatory imaging.

RESULTS

We enrolled 260 patients from 10 institutions in Europe and Mexico. The mean age was 42 years and 74% were female. Intracranial hemorrhage was found in 102 (39%). Among them parenchymal hemorrhage occurred in 64 (63%), in addition, small juxta-cortical hemorrhage was found in 30 (29%), subarachnoid hemorrhage in 24 (24%) and subdural hemorrhage in 11 (11%). Multiple concomitant types of hemorrhage occurred in 23 (23%). Older age and superior sagittal thrombosis involvement were associated with presence of hemorrhage. The number of thrombosed venous sinuses was not associated with intracranial hemorrhage (median number IQRInterquartile ratio] of sinuses/veins involved with hemorrhage 2 (1-3) vs. 2 (1-3) without hemorrhage, p = 0.4).

CONCLUSION

The high rate of intracranial hemorrhage in cerebral venous thrombosis is not explained by widespread involvement of the venous sinuses. Superior sagittal sinus involvement is associated with higher bleeding risk.