Arterial spin labeling-MR may be an alternative to SPECT for evaluating cerebral perfusion in patients with unilateral middle cerebral artery stenosis

Impact of perioperative cerebral blood flow evaluation using arterial spin labeling in a patient undergoing carotid artery stenting

BACKGROUND

Hyperperfusion syndrome (HPS) is one of the most serious complications after carotid artery stenting (CAS). Arterial spin labeling (ASL) is a noninvasive method for assessing cerebral perfusion. This study aimed to evaluate the utility of ASL compared to that of SPECT in evaluating changes in intracranial blood flow during the perioperative period of CAS.

METHODS

We retrospectively reviewed prospectively collected data from 49 cases of CAS conducted for symptomatic and asymptomatic carotid artery stenosis. We calculated the relative cerebral blood flow (rCBF) from ASL (post labeling delay [PLD] of 1500 ms and 2500 ms) and SPECT, both pre- and post-CAS. Cerebrovascular reactivity (CVR) was assessed using SPECT with an acetazolamide challenge. We defined the change rate from PLD 1500 ms to 2500 ms before CAS as ΔrASL.

RESULTS

Hyperperfusion phenomenon was observed in four cases (8.2 %), with one case (2.0 %) resulting in cerebral hemorrhage and diagnosed as HPS. Positive correlations were noted between ASL and SPECT at both pre- and post-CAS (r = 0.42-0.65, p < 0.01). A negative correlation was found between ΔrASL obtained from the two PLDs before CAS and CVR (r=-0.41, p < 0.01).

CONCLUSIONS

ASL using two PLDs is a useful method for evaluating changes in CBF during the perioperative period of CAS.

Impaired iron metabolism and cerebral perfusion patterns in unilateral middle cerebral artery stenosis or occlusion: Insights from quantitative susceptibility mapping

BACKGROUND AND PURPOSE

Cerebral hypoperfusion caused by stenosis or occlusion of the middle cerebral artery (MCA) may be followed by impaired iron metabolism. We explored the association between iron changes of gray matter (GM) nuclei subregions and different cerebral perfusion patterns in patients with chronic unilateral middle cerebral artery (MCA) stenosis or occlusion using quantitative susceptibility imaging (QSM).

METHODS

Sixty-one patients with unilateral MCA stenosis or occlusion were recruited and scored with Alberta-Stroke-Program-Early-CT-Score (ASPECTS) based on relative cerebral blood flow (rCBF) measurements to calculate the number of corresponding hypoperfusion subregions, and then divided into an extensive-hypoperfusion group (EH group), regional-hypoperfusion group (RH group), and normal-perfusion group (Control group) accordingly. The measured magnetic susceptibility of GM nuclei subregions was compared between the lesion and contralateral side for each group and among the three groups. Correlation analysis was performed to assess the relationships of magnetic susceptibility of GM nuclei with mean rCBF, National-Institutes-of-Health-stroke-scale (NIHSS) and modified-Rankin-scale (mRS) scores.

RESULTS

Magnetic susceptibility in the putamen (PU) and globus pallidus (GP) at the lesion side was higher in the EH and RH groups compared with the contralateral side (all P < 0.05). Susceptibility in the lesion side PU and GP showed negative correlations with mean rCBF and positive correlations with NIHSS and mRS scores (all P < 0.05).

CONCLUSION

Our findings demonstrate that chronic cerebral hypoperfusion might be one cause of cerebral abnormal iron metabolism. In addition, magnetic susceptibility of PU and GP seems to be correlated with stroke scale scores, suggesting that iron deposition may play an important role in neurologic deficits after ischemic stroke.

Prognostic value of multi-PLD ASL-based cerebral perfusion ASPECTS in acute ischemic stroke

Introduction

We aimed to verify the application value of the Alberta Stroke Program Early CT Score (ASPECTS) based on multiple post-labeling delay (multi-PLD) arterial spin labeling (ASL) for outcome assessment in acute ischemic stroke (AIS) patients.

Method

The endpoint was modified Rankin scale score at 90 days (90-day mRS). Patients were divided into the good outcome (0-2) and poor outcome (3-6) groups. The independent samples t-test, Mann-Whitney U-test, and χ2-test were used to compare clinical and imaging parameters between groups. We used partial correlation analysis to evaluate the relationships between ASPECTS and outcomes. Multivariate logistic regression analysis was used to examine potential independent prognostic indicators. The receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of the independent prognostic indicators in predicting outcomes.

Results

Fifty-five AIS patients were included. The good outcome group had a lower baseline National Institutes of Health Stroke Scale (NIHSS; Z = -3.413, P < 0.001) and infarct core volume (ICV; Z = -3.114, P = 0.002) as well as higher cerebral blood flow (CBF)-ASPECTS (Z = -3.835, P < 0.001) and cerebral blood volume (CBV)-ASPECTS (Z = -4.099, P < 0.001). Higher CBF-ASPECTS (r = -0.459, P = 0.001), and CBV-ASPECTS (r = -0.502, P < 0.001) were associated with a lower 90-day mRS. The baseline NIHSS, CBF-ASPECTS, and CBV-ASPECTS were identified as independent prognostic indicators. The AUCs of the baseline NIHSS, CBF-ASPECTS, and CBV-ASPECTS were 83.3, 87.4, and 89.9%, respectively. Combining NIHSS with CBF-ASPECTS and CBV-ASPECTS, the AUC significantly improved to 96.3%. The combined three factors showed a significant difference compared to the baseline NIHSS (Z = 2.039, P = 0.041) and CBF-ASPECTS (Z = 2.099, P = 0.036), but no difference with CBV-ASPECTS (Z = 1.176, P = 0.239).

Conclusions

The ASPECTS based on multi-PLD ASL is a valuable tool for identifying independent prognostic indicators and assessing clinical outcomes in AIS patients. The baseline NIHSS, combined with CBF-ASPECTS and CBV-ASPECTS, enhances the predictive efficacy of clinical outcomes in AIS patients. The CBV-ASPECTS alone can offer comparable predictive efficacy to the combination.

Ocular Blood Flow Measurements in Diabetic Retinopathy Using 3D Pseudocontinuous Arterial Spin Labeling

BACKGROUND

Distinguishing between the two broad categories of diabetic retinopathy (DR), nonproliferative DR (NPDR) and proliferative DR (PDR), is significant, as the therapeutic strategies for each are completely different.

PURPOSE

To characterize the ocular blood flow (OBF) of DR patients and evaluate the potential utility of OBF values in categorizing DR.

STUDY TYPE

Prospective.

SUBJECTS

A total of 41 DR patients (82 eyes) were recruited in our study. Group 1 comprised 48 eyes with NPDR, and Group 2 comprised 34 eyes with PDR.

FIELD STRENGTH/SEQUENCE

3D pseudocontinuous arterial spin labeling (3D-pcASL) with two postlabeling delays (PLDs) was acquired at 3.0T MR.

ASSESSMENT

OBF values were independently obtained by two doctors from the OBF map.

STATISTICAL TESTS

OBF values and clinical characteristics were compared between the groups using two-sample t-tests and chi-square tests. Receiver operating characteristic (ROC) curves were obtained, and the area under the curve (AUC) was calculated. The consistency of OBF values reported by the two doctors was evaluated using the intraclass correlation coefficient (ICC).

RESULTS

OBF values at PLDs of 1.5 seconds and 2.5 seconds were significantly lower in Group 2 than in Group 1 (P < 0.05 for both PLDs). The OBF values of Group 2 showed a greater increase than those of Group 1 from PLD 1.5 to 2.5 seconds. The AUC of OBF at the 1.5 seconds PLD was 0.90, with a cutoff of 7.73 mL/min/100 g, and the AUC of the OBF at the 2.5 seconds PLD was 0.75, with a cutoff of 8.44 mL/min/100 g. The ICC between the two observers was 0.844 for the OBF at 1.5 seconds PLD and 0.872 for the OBF at 2.5 seconds PLD.

DATA CONCLUSION

PDR can be differentiated from NPDR by the value of OBF as measured by 3D-pcASL.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 1.