Journal of Neuroimaging最新文献

Background and Purpose

Right-to-left shunt (RLS), usually related to a patent foramen ovale (PFO), is an important cause of cryptogenic stroke (CS) in young patients. Transcranial Doppler (TCD) with an agitated saline bubble study is a highly sensitive modality for RLS diagnosis using a transtemporal approach (TTD). However, a minority of patients have insufficient temporal bone windows. We aimed to evaluate the accuracy of transforaminal TCD (TFD) for RLS diagnosis.

Methods

We included patients with CS or transient ischemic attack who were tested in the standard protocol for RLS between March 2022 and February 2023. We evaluated the concordance of RLS grades between TFD and transesophageal echocardiogram (TEE) using the weighted kappa index. We also compared TTD and TFD approaches.

Results

Forty patients were included (66.7% men; median age 49 years). Medium or large RLS were found in 28 patients (70%) with TTD and in 27 patients with TFD (67.5%). Through TEE, 19 (82.6%) medium or large PFO were confirmed, and a high agreement rate of 0.684 (p = 0.0003) was observed for grading RLS. Moreover, the agreement rate of RLS grade between TTD and TFD was 0.73 (p < 0.0001).

Conclusion

TFD is a valid approach for RLS diagnosis, with substantial concordance with TEE in grading RLS. Our study found a good grade of agreement between TFD and TEE. Therefore, the value of TCD goes beyond quantifying RLS and could assist in identifying the patients with the largest RLS, who would gain the greatest benefit from PFO closure.

Background and Purpose

Silent brain infarcts (SBIs), which manifest as dot-like lesions on diffusion-weighted imaging (DWI) after endovascular procedures, are associated with an increased risk of stroke, dementia, and cognitive decline. We aimed to identify the factors associated with SBIs following middle cerebral artery (MCA) stenting or balloon angioplasty.

Methods

We retrospectively reviewed patients who underwent MCA stenting or balloon angioplasty, including those with symptomatic, atherosclerotic MCA stenosis of ≥50%. DWI scans were conducted before and after the procedure, and newly detected DWI lesions were classified as SBIs. We investigated the factors associated with the development of SBIs, and for patients with SBIs, we conducted a detailed analysis based on lesion location (cortex and perforator territory vs. cortex only vs. perforator territory only).

Results

Among 120 patients, 64 (53.3%) exhibited SBIs postprocedure. Factors significantly associated with SBIs included smaller stenosis diameter (odd ratio [95% confidence interval] = 0.03 [0.002–0.35], p = 0.006), longer stenosis length (1.24 [1.02–1.51], p = 0.033), higher MCA tortuosity (1.20 [1.07–1.34], p = 0.002), and diffuse involvement of MCA stenosis (3.99 [1.17–13.62], p = 0.027). Among the patients who exhibited SBIs, D-dimer (p = 0.002), C-reactive protein (p = 0.026), and hemoglobin A1c (p = 0.025) differed according to detailed mechanism.

Conclusions

Stenosis diameter, stenosis length, and MCA tortuosity were significantly associated with the development of SBIs following MCA stenting.

Background and Purpose

This study investigated the neural mechanisms underlying Parkinson's disease (PD) subtypes—tremor dominant (TD) and postural instability gait difficulty (PIGD)—by analyzing regional homogeneity (ReHo) values from resting-state functional MRI.

Methods

Fifty-nine PD patients (29 TD patients, 30 PIGD patients) and 30 healthy controls (HCs) were enrolled. ReHo values were analyzed via analysis of variance and a two-sample t-test, with age and sex as covariates. Correlations between ReHo values and clinical motor symptoms were also examined.

Results

Distinct ReHo patterns were observed in patients with the PD subtypes and HCs. TD patients presented decreased ReHo in the cerebellar–thalamic–cortical circuit, whereas PIGD patients presented lower ReHo in the striatum and supplementary motor area (SMA). TD patients had higher ReHo in the bilateral dorsolateral superior frontal gyrus and SMA but lower ReHo in the bilateral medial orbital part of the superior frontal gyrus and other regions on the left than PIGD patients. Specific brain area ReHo values were correlated with tremor scores, PIGD scores, and rigidity scores.

Conclusion

Different motor subtypes of PD patients and HCs showed distinct ReHo patterns. ReHo correlation with clinical traits suggests its value as a biomarker for subtype-specific diagnostic strategies.

Background and Purpose

The central vein sign (CVS) is a diagnostic imaging biomarker for multiple sclerosis (MS). FLAIR* is a combined MRI contrast that provides high conspicuity for CVS at 3 Tesla (3T), enabling its sensitive and accurate detection in clinical settings. This study evaluated whether CVS conspicuity of 3T FLAIR* is reliable across imaging sites and MRI vendors and whether gadolinium (Gd) contrast increases CVS conspicuity.

Methods

A cross-sectional, multicenter study recruited adults referred for possible diagnosis of MS at 10 sites. FLAIR* contrast was generated using high-resolution T2*-weighted (acquired pre- and post-injection of Gd) and T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) brain images at 3T from two MRI vendors. Lesions and veins were segmented to compute lesion-to-vein contrast-to-noise ratio (CNR_{lesion-to-vein}), a quantitative measure of CVS conspicuity. CNR_{lesion-to-vein} measures for pre- and post-Gd FLAIR* were compared across sites and vendors.

Results

Eighty-seven participants from nine sites were included in the analysis. There was no significant difference in mean CNR_{lesion-to-vein} between sites for pre-Gd (p-value = 0.07) or post-Gd (p-value = 0.27) FLAIR*. There were also no significant differences between vendors for pre-Gd (p-value = 0.10) or post-Gd (p-value = 0.31) FLAIR*. Patient-level pairwise differences in CNR_{lesion-to-vein} between pre-Gd and post-Gd FLAIR* revealed a significant increase for post-Gd FLAIR* (p-value < 0.001).

Conclusions

CVS conspicuity on 3T FLAIR* is consistent across imaging sites and MRI vendors. Moreover, Gd-based contrast agent significantly improved CVS conspicuity on 3T FLAIR*. These findings support the implementation of FLAIR* in clinical settings for MS.

Background and purpose

Prolonged length of stay (LOS) following a stroke is associated with unfavorable clinical outcomes. Factors predicting LOS in medium vessel occlusion (MeVO), impacting up to 40% of acute ischemic stroke (AIS) cases, remain underexplored. This study aims to investigate the predictors of LOS in AIS-MeVO.

Methods

We conducted a retrospective analysis of prospectively maintained stroke databases, comprising AIS cases with MeVO in the anterior circulation, assessed by adequate CT perfusion (CTP). Baseline and clinical data were obtained from electronic health records. Alberta Stroke Program Early CT Scores (ASPECTS) were calculated from non-contrast head CT. The perfusion mismatch volume (time to maximum > 6 s minus relative cerebral blood flow <30%) volume was reported from CTP. Multiple regression was employed to examine the relationship between baseline parameters and hospital LOS.

Results

A total of 133 patients (median age 71 [interquartile range 63–80] years, 59.4% females) were included in the study cohort. The perfusion mismatch volume significantly positively correlated with LOS (r = 0.264, p = 0.004). After adjusting for age, sex, hypertension, diabetes, prior stroke or transient ischemic attack, admission NIHSS, ASPECTS, Tan score, intravenous thrombolysis, mechanical thrombectomy (MT), and hemorrhagic transformation, a larger mismatch volume remained independently associated with longer hospital stays (β = 0.209, 95% confidence interval [CI] 0.006–0.412, p = 0.045). Additional significant determinants of longer hospital stay included admission NIHSS (β = 0.250, 95% CI: 0.060–0.440, p = 0.010) and MT (β = 0.208, 95% CI: 0.006–0.410, p = 0.044). Among patients who underwent MT (n = 83), multiple regression analysis incorporating both perfusion mismatch volume and admission NIHSS revealed that perfusion mismatch volume remained independently associated with LOS (β = 0.248, 95% CI: 0.019–0.471, p = 0.033), while admission NIHSS did not retain significance (β = 0.208, 95% CI: 0.019–0.433, p = 0.071).

Conclusions

In our cohort of AIS patients with MeVO in the anterior circulation, and particularly in those who underwent MT, the perfusion mismatch volume serves as an independent predictor of LOS. These findings offer critical valuable insights in clinical assessments and decision-making protocols of MT in AIS-MeVO.

Background and Purpose

MRI is crucial for multiple sclerosis (MS), but the relative value of portable ultra-low field MRI (pULF-MRI), a technology that holds promise for extending access to MRI, is unknown. We assessed white matter lesion (WML) detection on pULF-MRI compared to high-field MRI (HF-MRI), focusing on blinded assessments, assessor self-training, and multiplanar acquisitions.

Methods

Fifty-five adults with MS underwent pULF-MRI following their HF-MRI. Two neuroradiologists independently assessed pULF-MRI images in an evaluation process, including initial assessment blinded to HF-MRI, self-training with reference to HF-MRI and evaluation of 20 cases with additional T2-fluid-attenuated inversion recovery in an additional plane. A third rater conducted cross-referenced analysis with HF-MRI data to determine true-positive lesions, false-positive areas, and case-level sensitivity and positive predictive value.

Results

The mean age of participants was 50 years (standard deviation: 11; 74% women). Initially, Rater 2 marked more false-positive areas than Rater 1 (p = 0.003). After self-training, both raters embraced a conservative approach, with Rater 2 marking fewer false-positive areas (p = 0.01). Both raters maintained 100% case-level sensitivity and positive predictive value for detecting at least one WML, particularly in periventricular areas. Multiplanar acquisitions reduced both false-positive areas and true-positive lesions. True-positive lesions and false-positive areas had similar contrast-to-noise ratios in the juxtacortical region (p = 0.73) but not in periventricular, deep parenchymal regions (p = 0.004, p = 0.01).

Conclusion

With adequate training, radiological interpretation of pULF-MRI has high sensitivity and positive predictive value for MS lesions but should be approached conservatively. These results suggest utility for patient triage, potentially reducing diagnostic delay, and screening high-risk individuals.

Background and Purpose

Prolonged venous transit (PVT), derived from computed tomography perfusion (CTP) time-to-maximum (T_max) maps, reflects compromised venous outflow (VO) in acute ischemic stroke due to large vessel occlusion (AIS-LVO). Poor VO is associated with worse clinical outcomes, but pre-treatment markers predictive of PVT are not well described.

Methods

We conducted a retrospective analysis of 189 patients with anterior circulation AIS-LVO who underwent baseline CT evaluation, including non-contrast CT, CT angiography, and CTP. PVT was assessed on T_max maps; PVT+ was defined as T_max ≥ 10 s within the posterior superior sagittal sinus or torcula. Baseline clinical data were collected. Multivariable logistic regression identified independent associations between pre-treatment markers and PVT.

Results

PVT+ was identified in 65 patients (34%). In multivariable analysis, higher admission National Institutes of Health Stroke Scale (NIHSS) scores (adjusted odds ratio [aOR], 1.05 per point; 95% confidence interval [CI], 1.01–1.11; P  =  0.028) and male sex (aOR, 1.98; 95% CI, 1.03–3.89; P  =  0.043) were independently associated with PVT+.

Conclusions

Higher admission NIHSS scores and male sex are independently associated with PVT in anterior circulation AIS-LVO, suggesting that readily available clinical markers may help identify patients with poor VO profiles.

Background and Purpose

This study aims to investigate the longitudinal changes in translocator protein (TSPO) following stroke in different brain regions and potential associations with chronic brain infarction.

Methods

Twelve patients underwent SPECT using the TSPO tracer 6-Chloro-2-(4ʹ-123I-Iodophenyl)-3-(N,N-Diethyl)-Imidazo[1,2-a]Pyridine-3-Acetamide, as well as structural MRI, at 10, 41, and 128 days (median) after ischemic infarction in the middle cerebral artery. TSPO expression was measured in lesional (MRI lesion and SPECT lesion), connected (pons and ipsilesional thalamus), and nonconnected (ipsilesional cerebellum and contralesional occipital cortex) regions. Correlations were explored between the volume of chronic infarction and TSPO expression in nonconnected regions of interest (ROIs) at 128 days

Results

Throughout the study period, TSPO levels decreased by 24%–33% in lesional ROIs, while levels increased in connected ROIs by 35%–69% and in nonconnected ROIs by 53%–77%. At 128 days poststroke, TSPO expression in ipsilesional cerebellum positively correlated with chronic infarction volume (p = 0.001, r² = 0.78).

Conclusions

This study expands the current knowledge of spatial and temporal TSPO expression in humans by quantifying TSPO changes in lesional, connected, and nonconnected brain regions at three time points after cerebral infarction as well as correlating late-stage TSPO upregulation and chronic infarction volume.

[Correction added on January 29, 2025, after first online publication: The p and r2 values in the results section of the abstract have been corrected in this version].

Background and Purpose

Endovascular thrombectomy (EVT) is the standard for acute ischemic stroke from large vessel occlusion, but post-EVT functional independence varies. Brain atrophy, linked to higher cerebrospinal fluid volume (CSFV), may affect outcomes. Baseline CSFV could predict EVT benefit by assessing brain health. We aimed to quantify total CSFV from clinical T1-weighted (w) magnetic resonance imaging (MRI) to assess global brain atrophy and its association with functional outcomes following successful EVT.

Methods

We performed a retrospective analysis of patients achieving thrombolysis-in-cerebral-infarction ≥2b revascularization via prospectively maintained single-institution stroke thrombectomy registry (n = 432) between 2015 and 2021. We included 214 patients (mean age 67.5 ± 14.6, 49% female) with acceptable quality MRI within 14 days of EVT and available modified Rankin-scale (mRS) at 90 days post EVT. Clinical T1w images were transformed into high-resolution images using the convolutional neural-network SynthSR. FreeSurfer software was then used to estimate total cranial CSFV. To correct for head size, percentage of CSFV to intracranial volume was used.

Results

Baseline CSFV% significantly predicted 90-day mRS in an ordinal regression model adjusted for baseline mRS (p < 0.001). Further modeling was performed to account for age, sex, 24-h National-Institutes-Health-Stroke-Scale (NIHSS), smoking history, prior stroke, hypertension, congestive heart failure, hemoglobin-A1c, atrial fibrillation, and Alberta-Stroke-Program-Early-CT-Score (ASPECTS). Total CSFV% remained an independent predictor of 90-day mRS (p = 0.012). CSFV% did not significantly predict the occurrence of any type of hemorrhagic transformation in a logistic regression model.

Conclusions

Increased CSFV% correlates with poorer functional outcomes post EVT. Total CSFV% may serve as a useful imaging biomarker for clinicians determining patient prognostication prior to EVT.