Utility of relative ADC ratio in patient selection for endovascular revascularization of large vessel occlusion

The time threshold to reperfusion for DWI reversal in acute ischemic stroke depends on pre-interventional ADC value

PURPOSE

The aims of this study are to explore the apparent diffusion coefficient (ADC)-dependent thresholds for time to reperfusion in reversible lesions following mechanical thrombectomy for acute ischemic stroke, and to investigate the associated risks of hemorrhagic transformation.

METHODS

We conducted a retrospective case-control study, enrolling patients with large-vessel occlusion who underwent mechanical thrombectomy in Otaru General Hospital from 2016 to 2021. Reversible lesions were identified using volumetric ADC data, and the mean time from image to reperfusion (TIR) in each ADC range was compared between groups with and without reversible lesions, as well as those with and without parenchymal hematoma. The Wilcoxon rank sum test and chi-square test were used for comparison between two groups, and receiver operating characteristic curves were created to determine optimal thresholds.

RESULTS

Seventy-five patients were included and 581 volumetric data were obtained. The mean TIR in the group with reversible lesions was shorter than in that without, and time thresholds were 131, 123 and 112 min for ADC values > 540 × 10-6, 500-540 × 10-6 and 440-500 × 10-6 mm2/s, respectively. Furthermore, in patients with parenchymal hematoma, the mean TIR was significantly longer, and the average ADC value was significantly lower than those without hematoma.

CONCLUSION

The time thresholds for the irreversible ischemic core may vary depending on the ADC value, and they may be shorter when the ADC value is lower. Moreover, both the low ADC value and the late reperfusion might be associated with an increased risk of parenchymal hematoma.

Factors associated with decreasing diffusion-weighted imaging-positive area volume after mechanical thrombectomy in patients with large early ischemic changes

OBJECTIVES

This study aimed to evaluate the factors associated with decreasing diffusion-weighted imaging (DWI) positive areas in patients with large early ischemic changes after mechanical thrombectomy (MT).

MATERIALS AND METHODS

This retrospective single-center clinical study was conducted between January 2013 and December 2022. We included consecutive patients who underwent MT for acute large-vessel occlusion of the anterior circulation with low pretreatment DWI-Alberta Stroke Program Early Computed Tomography Scores (ASPECTS) (0-5), effective recanalization [thrombolysis in cerebral infarction (TICI) 2b or TICI3], and magnetic resonance imaging (MRI) acquired before and after MT. We measured the DWI-positive area volume before and after MT. The primary endpoint was the after/before-MT DWI-positive area-volume ratio.

RESULTS

In total, 28 patients were included in this study. Eight patients (29%) had an after/before-MT DWI-positive area-volume ratio of <1. The median mean apparent diffusion coefficient (ADC) levels of the DWI-positive areas in the groups with a ratio of <1 or >1 were 717 × 10⁶ mm2/s and 637 × 106 mm2/s, respectively (p = 0.011). Multivariate logistic regression analysis showed that ADC level (OR, 1.020 [95% confidence intervals (CIs), 1.001-1.040]; p = 0.040) was an independent predictor of a decreased DWI-positive area after MT. There was a negative correlation between the mean ADC level and the after/before-MT DWI-positive area-volume ratio (p < 0.001, |ρ| = 0.650), and the mean pretreatment ADC cutoff level was 649 × 106 mm2/s (area under the curve (AUC) = 0.806) for predicting a volume ratio of <1.

CONCLUSIONS

The mean ADC level before-MT correlated with the after/before-MT DWI-positive area-volume ratio. A mean pretreatment ADC cutoff level of 649 × 106 mm2/s predicted a decreased DWI-positive area after MT.

ADC Level is Related to DWI Reversal in Patients Undergoing Mechanical Thrombectomy: A Retrospective Cohort Study

BACKGROUND AND PURPOSE

In patients with ischemic stroke, DWI lesions can occasionally be reversed by reperfusion therapy. This study aimed to ascertain the relationship between ADC levels and DWI reversal in patients with acute ischemic stroke who underwent recanalization treatment.

MATERIALS AND METHODS

We conducted a retrospective cohort study in patients with acute ischemic stroke who underwent endovascular mechanical thrombectomy with successful recanalization between April 2017 and March 2021. DWI reversal was assessed through follow-up MR imaging approximately 24 hours after treatment.

RESULTS

In total, 118 patients were included. DWI reversal was confirmed in 42 patients. The ADC level in patients with reversal was significantly higher than that in patients without reversal. Eighty-three percent of patients with DWI reversal areas had mean ADC levels of ≥520 × 10^-6 mm²/s, and 71% of patients without DWI reversal areas had mean ADC levels of <520 × 10^-6 mm²/s. The mean ADC threshold was 520 × 10^-6 mm²/s with a sensitivity and specificity of 71% and 83%, respectively. In multivariate analysis, the mean ADC level (OR, 1.023; 95% CI, 1.013-1.033; P < .0001) was independently associated with DWI reversal. Patients with DWI reversal areas had earlier neurologic improvement (NIHSS at 7 days) than patients without reversal areas (P < .0001).

CONCLUSIONS

In acute ischemic stroke, the ADC value is independently associated with DWI reversal. Lesions with a mean ADC of ≥520 × 10^-6 mm²/s are salvageable by mechanical thrombectomy, and DWI reversal areas regain neurologic function. The ADC value is easily assessed and is a useful tool to predict viable lesions.

Cerebral Hyperperfusion and Concomitant Reversible Lesion at the Splenium after Direct Revascularization Surgery for Adult Moyamoya Disease: Possible Involvement of MERS and Watershed Shift Phenomenon

Superficial temporal artery (STA)–middle cerebral artery (MCA) bypass is the standard surgical treatment for moyamoya disease (MMD). Local cerebral hyperperfusion (CHP) is one of the potential complications, which could enhance intrinsic inflammation and oxidative stress in MMD patients and accompany concomitant watershed shift (WS) phenomenon, defined as the paradoxical decrease in the cerebral blood flow (CBF) near the site of CHP. However, CHP and simultaneous remote reversible lesion at the splenium have never been reported. A 22-year-old man with ischemic-onset MMD underwent left STA–MCA bypass. Although asymptomatic, local CHP and a paradoxical CBF decrease at the splenium were evident on N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography 1 day after surgery. The patient was maintained under strict blood pressure control, but he subsequently developed transient delirium 4 days after surgery. MRI revealed a high-signal-intensity lesion with a low apparent diffusion coefficient at the splenium. After continued intensive management, the splenial lesion disappeared 14 days after surgery. The patient was discharged without neurological deficits. Catheter angiography 2 months later confirmed marked regression of posterior-to-anterior collaterals via the posterior pericallosal artery, suggesting dynamic watershed shift between blood flow supplies from the posterior and anterior circulation. Mild encephalitis/encephalopathy with a reversible splenial lesion could explain the pathophysiology of the postoperative splenial lesion in this case, which is associated with generation of oxidative stress, enhanced inflammation, and metabolic abnormalities. Rapid postoperative hemodynamic changes, including local CHP and concomitant WS phenomenon, might participate in the formation of the splenial lesion.

Reversible diffusion-weighted imaging lesions in acute ischemic stroke: A systematic review

OBJECTIVES

To systematically review the literature for reversible diffusion-weighted imaging (DWIR) lesions and to describe its prevalence, predictors, and clinical significance.

METHODS

Studies were included if the first DWI MRI was performed within 24 hours of stroke onset and follow-up DWI or fluid-attenuated inversion recovery (FLAIR)/T2 was performed within 7 or 90 days, respectively, to measure DWIR. We abstracted clinical, imaging, and outcomes data.

RESULTS

Twenty-three studies met the study criteria. The prevalence of DWIR was 26.5% in DWI-based studies and 6% in FLAIR/T2-based studies. DWIR was associated with recanalization or reperfusion of the ischemic tissue with or without the use of tissue plasminogen activator (t-PA) or endovascular therapy, earlier treatment with t-PA, shorter time to endovascular therapy after MRI, and absent or less severe perfusion deficit within the DWI lesion. DWIR was associated with early neurologic improvement in 5 of 6 studies (defined as improvement in the NIH Stroke Scale (NIHSS) score by 4 or 8 points from baseline or NIHSS score 0 to 2 at 24 hours after treatment or at discharge or median NIHSS score at 7 days) and long-term outcome in 6 of 7 studies (defined as NIHSS score ≤1, improvement in the NIHSS score ≥8 points, or modified Rankin Scale score up to ≤2 at 30 or 90 days) likely due to reperfusion.

CONCLUSIONS

DWIR is seen in up to a quarter of patients with acute ischemic stroke, and it is associated with good clinical outcome following reperfusion. Our findings highlight the pitfalls of DWI to define ischemic core in the early hours of stroke.

Utility of Minimum Apparent Diffusion Coefficient Ratios in Alberta Stroke Program Early CT Score Regions for Deciding on Stroke Therapy

BACKGROUND AND PURPOSE

Therapeutic indications for recombinant tissue plasminogen activator therapy and endovascular therapy need to be assessed for patients with hyperacute ischemic stroke. We investigated the relationship between the minimum apparent diffusion coefficient ratios in each Alberta Stroke Program Early CT Score region and reversible lesion in patients with hyperacute ischemic stroke receiving recombinant tissue plasminogen activator therapy and/or treated with endovascular therapy.

MATERIALS AND METHODS

We retrospectively evaluated 29 patients with first ischemic stroke due to stenosis/occlusion of the internal carotid artery or horizontal portion of the middle cerebral artery that was successfully recanalized by recombinant tissue plasminogen activator therapy and/or treated with endovascular therapy. We measured the minimum apparent diffusion coefficient value in each Alberta Stroke Program Early CT Score region (11 regions) and calculated the ratio.

RESULTS

There was a significant difference in minimum apparent diffusion coefficient ratios between regions that included and did not include infarction (P < .0001), which were distinguishable with a cutoff value of .808 (area under the curve = .80, P < .001). A statistical difference in the proportion of infarction with the cutoff value was observed between patients treated with endovascular therapy and receiving recombinant tissue plasminogen activator therapy alone (9.9% versus 24.6%, P = .0041) and between patients with affected middle cerebral and internal carotid arteries (7.0% versus 24.2%, P = .0002). The lowest apparent diffusion coefficient ratio was associated with the time to recombinant tissue plasminogen activator injection.

CONCLUSIONS

Minimum apparent diffusion coefficient ratios in Alberta Stroke Program Early CT Score regions are useful in predicting therapeutic effect.

Can MRI water apparent diffusion coefficient (ADC) value discriminate between idiopathic normal pressure hydrocephalus, Alzheimer's disease and subcortical vascular dementia?

Numerous similarities in MRI and clinical symptoms exist between Alzheimer's disease (AD), subcortical vascular dementia (sVD) and possible idiopathic normal pressure hydrocephalus (iHPN). The aim of this study is to explore mean apparent coefficient diffusion (ADC) difference between theses diseases in different periventricular and deep white matter areas, as compared to healthy controls. This retrospective study analyzed mean ADC values of 120 patients in normal appearing deep white matter and lenticular nuclei, frontal, caudate nuclei corpus and parietal periventricular and deep white matter areas INPH group showed significantly lower ADC than sVD group in frontal periventricular region (1567.10^-6mm²/s vs 1755.10^-6mm²/s; P=0.0009) and in parietal deep region (1087.10^-6mm²/s vs 1271.10^-6mm²/s; P=0.0052), but showed significantly higher ADC in lenticular nuclei ROI (834.10^-6mm²/s vs 753.10^-6mm²/s; P=0.002). The comparison between iNPH and sVD showed a cut-off value of 1676.10^-6mm²/s (sensitivity 0.70, specificity 0.77) in periventricular frontal area. INPH group, in comparison with NA group, showed significantly higher ADC in all ROIs. The iNPH group also showed significantly higher ADC than AD group in all ROIs. AD group showed significantly lower ADC than sVD group in all regions, except in normal appearing lenticular nuclei and caudate nuclei corpus deep ROI. SVD group showed significantly higher ADC than NA in all ROIs, except in normal appearing lenticular nucleus ROI. Different patterns of ADC values can differentiate between AD, sVD and iNPH, even when other MRI sequences appear morphologically similar.