Arterial Spin Labeling Perfusion Research Articles

Intracerebral steal phenomenon in symptomatic carotid artery disease

Background and purposeIntracerebral steal is a paradoxical vasodilatory response that reduces cerebral blood flow (CBF) in hemodynamically compromised brain tissue when blood is rerouted to more healthy areas. The aim of our study was to investigate the presence and extent of steal in patients with steno-occlusive internal carotid artery (ICA) disease, and to assess its relation with collateral blood flow through the circle of Willis (CoW). Materials and methodsThirty-eight patients with symptomatic steno-occlusive ICA disease underwent MRI examination with arterial spin labeling (ASL) perfusion imaging before and after a vasodilatory challenge. Intracerebral steal was defined as a decline in CBF after acetazolamide. Collateral flow via the CoW was assessed with time-of-flight and flow direction MR angiography (MRA) through the CoW was assessed with 2D phase-contrast MRA's. ResultsEight of 38 patients (21%) had steal in the hemisphere ipsilateral to the symptomatic ICA (mean tissue volume with steal, 6.9 ± 4.1 mL; mean CVR, −11 ± 30%). Cerebrovascular reactivity (CVR) was lower in the middle cerebral artery flow territory of the affected hemisphere in patients with steal compared those without (P = 0.002). Collateral blood flow was impaired in 4 of the 8 patients with steal. These patients had a larger area of steal (P = 0.002). ConclusionsIntracerebral steal occurs in patients with obstructive ICA disease and can be assesses at brain tissue level with ASL perfusion MRI. Its presence is related to more severely declined CVR in the surrounding brain tissue area and the volume is associated with impaired primary collateral blood flow through the CoW.

A framework for motion correction of background suppressed arterial spin labeling perfusion images acquired with simultaneous multi-slice EPI.

PurposeWhen using simultaneous multi‐slice (SMS) EPI for background suppressed (BGS) arterial spin labeling (ASL), correction of through‐plane motion could introduce artefacts, because the slices with most effective BGS are adjacent to slices with the least BGS. In this study, a new framework is presented to correct for such artefacts.MethodsThe proposed framework consists of 3 steps: (1) homogenization of the static tissue signal over the different slices to eliminate most inter‐slice differences because of different levels of BGS, (2) application of motion correction, and (3) extraction of a perfusion‐weighted signal using a general linear model. The proposed framework was evaluated by simulations and a functional ASL study with intentional head motion.ResultsSimulation studies demonstrated that the strong signal differences between slices with the most and least effective BGS caused sub‐optimal estimation of motion parameters when through‐plane motion was present. Although use of the M0 image as the reference for registration allowed 82% improvement of motion estimation for through‐plane motion, it still led to residual subtraction errors caused by different static tissue signal between control and label because of different BGS levels. By using our proposed framework, those problems were minimized, and the accuracy of CBF estimation was improved. Moreover, the functional ASL study showed improved detection of visual and motor activation when applying the framework as compared to conventional motion correction, as well as when motion correction was completely omitted.ConclusionWhen combining BGS‐ASL with SMS‐EPI, particular attention is needed to avoid artefacts introduced by motion correction. With the proposed framework, these issues are minimized.

Cerebral Blood Flow and Marrow Diffusion Alterations in Children with Sickle Cell Anemia after Bone Marrow Transplantation and Transfusion.

Hematopoietic marrow hyperplasia and hyperperfusion are compensatory mechanisms in sickle cell anemia. We have observed marrow diffusion and arterial spin-labeling perfusion changes in sickle cell anemia following bone marrow transplantation. We aimed to compare arterial spin-labeling perfusion and marrow diffusion/ADC values in patients with sickle cell anemia before and after bone marrow transplantation or transfusion. We reviewed brain MRIs from patients with sickle cell anemia obtained during 6 consecutive years at a children's hospital. Quantitative marrow diffusion values were procured from the occipital and sphenoid bones. Pseudocontinuous arterial spin-labeling perfusion values (milliliters/100 g of tissue/min) of MCA, anterior cerebral artery, and posterior cerebral artery territories were determined. Territorial CBF, whole-brain average CBF, and marrow ADC values were compared for changes before and after either bone marrow transplantation or transfusion. Bone marrow transplantation and transfusion groups were compared. Two-tailed paired and unpaired Student t tests were used; P < .05 was considered significant. Fifty-three examinations from 17 patients with bone marrow transplantation and 29 examinations from 9 patients with transfusion were included. ADC values significantly increased in the sphenoid and occipital marrow following bone marrow transplantation in contrast to patients with transfusion (P > .83). Whole-brain mean CBF significantly decreased following bone marrow transplantation (77.39 ± 13.78 to 60.39 ± 13.62 ml/100 g tissue/min; P < .001), without significant change thereafter. CBF did not significantly change following the first (81.11 ± 12.23 to 80.25 ± 8.27 ml/100 g tissue/min; P = .47) or subsequent transfusions. There was no significant difference in mean CBF between groups before intervention (P = .22). Improved CBF and marrow diffusion eventuate following bone marrow transplantation in children with sickle cell anemia in contrast to transfusion therapy.

Arterial Spin Labeling MRI to Measure Cerebral Blood Flow in Untreated Ischemic Stroke.

This study aims to investigate the significance of regional hyperperfusion (RH) detected by arterial spin labeling (ASL) in a group of untreated stroke patients, within 24-36 hours after symptom onset. The relationship between RH volume and infarcted volume (DIV) as defined on diffusion weighted images (DWIs) was evaluated. Of the 346 consecutive acute stroke patients who attended our center, we retrospectively reviewed MRI studies of 47 patients who were ineligible for standard treatment with intravenous tissue plasminogen activator. The MRI study included ASL and DWI. The ASL-derived cerebral blood flow (CBF) maps were coregistered on the DWI images. RH volume and DIV were calculated and compared. Patient NIHSS scores were also evaluated at admission, discharge, and after 1 and 6-month follow-up. Twenty-two patients showed RH with CBF twice than baseline. In all 22 patients, RH overlaps with DWI infarcted area. No significant difference (P = .94) between RH volume and DIV was found (7.2 ± 9.6 and 9.0 ± 11.9 cm3 ). The Pearson's correlation coefficient between RH and DIV was .93. On univariate analysis, a significant difference was found between patient's groups on NIHSS at any time points, after covariates adjustment NIHSS difference was significant only at admission. The study showed that ASL perfusion could be an integral part of the MRI examination in the assessment of 24-36 hours not-treated stroke patients as sustained RH group had improved outcomes. More importantly, ASL perfusion may provide evidence of beneficial effects of reperfusion induced by recanalization treatment.

Comparative Evaluation of Brain Tuberculosis and Metastases Using Combined Analysis of Arterial Spin Labeling Perfusion and Diffusion Tensor Imaging

PurposeTo differentiate intra-axial tuberculomas (TB) from metastases based on quantitative differences in the perfusion and diffusion indices of lesion and perilesional edema using arterial spin labeling (ASL) and diffusion tensor imaging (DTI) techniques. Materials and methodsThis prospective study included newly diagnosed untreated 12 patients of TB and 13 of metastases who underwent routine magnetic resonance imaging including DTI and ASL sequences. A region of interest analysis was performed and cerebral blood flow (CBF) values of lesion (L), perilesional edema (PE), and normal contralateral white matter (CWM) were calculated. To account for individual patient variation CBF values were normalized (n) to CWM to obtain the nCBFL and nCBFPE ratios. Similarly, DTI data was processed to obtain fractional anisotropy (FA), mean diffusivity, radial diffusivity, and axial diffusivity values from the lesion and PE. ResultsMetastatic lesions revealed statistically significant (p = 0.001) high values of median nCBFL than TB whereas the difference in the median nCBFPE was not statistically significant (p = 0.174). TB showed higher median FAL compared to metastases (p = 0.031) while no statistically significant difference was found in mean values of other diffusion parameters such as mean diffusivity, radial diffusivity and axial diffusivity. Analysis by the receiver operating characteristic curve method revealed a cut-off value of ≥2.865 for nCBFL (Sensitivity = 0.85, Specificity = 0.84, positive predictive value (PPV) = 0.85, Negative predictive value (NPV) = 0.83) and ≤0.073 for FAL (Sensitivity = 0.77, Specificity = 0.58, PPV = 0.67, NPV = 0.70) in differentiating metastases from TB. ConclusionCombined analysis of noncontrast ASL perfusion and DTI technique may markedly benefit in differentiation of TB from metastases.

Feasibility and utility of arterial spin labelling perfusion in neuro-oncology MRI protocols in the UK

Arterial spin labelling, (ASL) is an MRI perfusion technique that uses endogenous contrast and is currently underused in neuro-oncology MRI protocols in the UK. The purpose of this study was to examine the feasibility, ease of implementation and added value of arterial spin labelling (ASL) perfusion imaging in neuro-oncology protocols. Radiographers at a large tertiary MRI centre received in-house training in protocol selection and performing pseudo-continuous ASL (pcASL). During a 10 month period, 104 consecutive patients with gliomas, undergoing diagnostic MRI at 3.0 T, underwent an extended MRI protocol that included pcASL. ASL perfusion weighted images (ASL-PWI) were automatically generated by the scanner and archived together with conventional imaging. A qualitive retrospective survey was performed for feedback on the process. A sub-group of patients with available follow up imaging (n=39) were selected for further analysis (n=39: 20 glioblastoma multiforme, 15 astrocytoma, 4 oligodendroglioma). Two observers examined images and concluded RANO scores in two parts: conventional images alone and conventional imaging with ASL-PWI. Confidence was measured using Likert scales 1–5 (1,very unconfident to 5, very confident) and differences compared. Lastly, all diagnoses were checked against follow up imaging. 90% of radiographers felt either confident or very confident in performing ASL technique. 100% of reviewed PWIs were considered diagnostic quality. A statistically significant increase in average confidence levels was observed for inclusion of ASL (4.44 (SD 0.8)) compared to conventional imaging alone (4.02 (SD 0.65)). ASL is a reliable, non-contrast, low cost and well tolerated technique that can be easily implemented. ASL-PWI can be produced at time of scanning which can be utilised to build confidence in assessing response to treatment in low and high grade gliomas.

Effects of Dehydration on Brain Perfusion and Infarct Core After Acute Middle Cerebral Artery Occlusion in Rats: Evidence From High-Field Magnetic Resonance Imaging.

Background: Dehydration is common among ischemic stroke patients and is associated with early neurological deterioration and poor outcome. This study aimed to test the hypothesis that dehydration status is associated with decreased cerebral perfusion and aggravation of ischemic brain injury.Methods: Diffusion-weighted imaging and arterial spin labeling perfusion MR imaging were performed on rats with middle cerebral artery occlusion (MCAO) by using a 9.4T MR imaging scanner to measure the volume of infarction and relative cerebral blood flow (rCBF) after infarction. Twenty-five rats were assigned to either a dehydration group or normal hydration group, and dehydration status was achieved by water deprivation for 48 h prior to MCAO.Results: The volume of the infarction was significantly larger for the dehydration group at the 4th h after MCAO (p = 0.040). The progression in the infarct volume between the 1st and 4th h was also larger in the dehydration group (p = 0.021). The average rCBF values of the contralateral normal hemispheres at the 1st and the 4th h were significantly lower in the dehydration group (p = 0.027 and 0.040, respectively).Conclusions: Our findings suggested that dehydration status is associated with the progression of infarct volume and decreases in cerebral blood flow during the acute stage of ischemic stroke. This preliminary study provided an imaging clue that more intensive hydration therapies and reperfusion strategies are necessary for the management of acute ischemic stroke patients with dehydration status.

Significance of arterial spin labeling perfusion and susceptibility weighted imaging changes in patients with transient ischemic attack: a prospective cohort study

BackgroundIn a prospective cohort of patients with transient ischemic attack (TIA), we investigated usefulness and feasibility of arterial spin labeling (ASL) perfusion and susceptibility weighted imaging (SWI) alone and in combination with standard diffusion weighted (DWI) imaging in subacute diagnostic work-up. We investigated rates of ASL and SWI changes and their potential correlation to lasting infarction 8 weeks after ictus.MethodsPatients with TIA underwent 3T-MRI including DWI, ASL and SWI within 72 h of symptom onset. We defined lasting infarction as presence of 8-week MRI T2-fluid attenuated inversion recovery (FLAIR) hyperintensity or atrophy in the area of initial DWI-lesion.ResultsWe included 116 patients. Diffusion and perfusion together identified more patients with ischemia than either alone (59% vs. 40%, p < 0.0001). The presence of both diffusion and perfusion lesions had the highest rate of 8-week gliosis scars, 65% (p < 0.0001). In white matter, DWI-restriction was the determinant factor for scar development. However, in cortical gray matter half of lesions with perfusion deficit left a scar, while lesions without perfusion change rarely resulted in scars (56% versus 21%, p = 0.03). SWI lesions were rare (6%) and a subset of perfusion lesions. SWI-lesions with DWI-lesions were all located in cortical gray matter and showed high scar rate.ConclusionsASL perfusion increased ischemia detection in patients with TIA, and was most useful in conjunction with DWI. ASL was fast, robust and useful in a subacute clinical diagnostic setting. SWI had few positive findings and did not add information.Trial Registration.http://www.clinicaltrials.gov. Unique Identifier NCT01531946, prospectively registered February 9, 2012.

Spatially adaptive unsupervised multispectral nonlocal filtering for improved cerebral blood flow mapping using arterial spin labeling magnetic resonance imaging

BackgroundCerebral blood flow (CBF) is an emerging biomarker for normal aging and neurodegenerative diseases. Arterial spin labeling (ASL) perfusion MRI permits noninvasive quantification of CBF. However, high-quality mapping of CBF from ASL imaging is challenging, largely due to noise. New methodWe demonstrate the ability of the recently introduced nonlocal estimation of multispectral magnitudes (NESMA) filter to greatly improve determination of CBF estimates from ASL imaging data. We evaluated the results of NESMA-ASL for CBF mapping from data obtained on human brain (n = 10) across a wide age range (21–74 years) using a standard clinical protocol. Results were compared to those obtained from unfiltered images or filtered images using conventional and advanced filters. Quantitative analyses for different spatial image resolutions and signal-to-noise ratios, SNRs, were also conducted. ResultsOur results demonstrate the potential of NESMA-ASL to permit high-quality high-resolution CBF mapping. NESMA-ASL substantially reduces random variation in derived CBF estimates while preserving edges and small structures, with minimal bias and dispersion in derived CBF estimates. Comparison with existing methodsNESMA-ASL outperforms all evaluated filters in terms of noise reduction and detail preservation. Further, unlike other filters, NESMA-ASL is straightforward to implement requiring only one user-defined parameter, which is relatively insensitive to SNR or local image structure. ConclusionsIn-vivo estimation of CBF in the human brain from ASL imaging data was markedly improved through use of the NESMA-ASL filter. The use of NESMA-ASL may contribute significantly to the goal of high-quality high-resolution CBF mapping within a clinically feasible acquisition time.

OA023] Multiparametric MRI measurements of renal perfusion and oxygenation

Purpose Renal medullary flow abnormalities have been implicated in the pathogenesis of primary and secondary hypertension. Still, due to the difficulties involved, combined measurements of medullary perfusion and oxygenation have only recently been reported. Using MRI, we have measured changes in renal flow, perfusion and oxygenation in healthy humans during activation of the sympathetic nerve system and after injection of a diuretic. Methods We measured changes in renal perfusion and blood oxygenation in 10 healthy subjects during handgrip exercise (HGE) and after furosemide injections on two occasions in a 3 Tesla MR-scanner. For the two interventions, renal arterial flow (RAF) data were acquired using phase contrast (PC-MRI), perfusion using arterial spin labeling (ASL) and changes in blood oxygenation were monitored using both T 2 ∗ measurements and blood oxygenation dependent (BOLD) imaging. Results HGE induced a decrease of RAF by 17.4 ± 7%, and an increase of oxygenation with a Δ T 2 ∗ of 22 ± 9% in the renal medulla despite a significant drop in medullary perfusion (−12 ± 5%). In the renal cortex on the other hand, both perfusion and oxygenation decreased significantly. After furosemide injection, mean T 2 ∗ values in the renal medulla increased by 45% (p T 2 ∗ and ASL perfusion in renal cortex had CV values of 4.2%, 5.1%, and 6.4% and 11.2% respectively in the medulla. Conclusion Measurements of RAF, BOLD and perfusion in renal cortex and medulla were acquired for the first time in healthy subjects during hand-grip testing and furosemide injection. Measurements from both interventions reveal that while changes in RAF, cortical perfusion and cortical oxygenation were synonymous, medullary oxygenation increased independently of perfusion after a diuretic injection and contrary to decreased perfusion during HGE induced sympathetic activation. These techniques may be useful in pathophysiologic studies of patients with hypertension or renal artery stenosis, and a better understanding of the mechanisms regulating medullary oxygenation.

Arterial spin-labeling perfusion imaging of childhood encephalitis: correlation with seizure and clinical outcome.

In childhood encephalitis, perfusion abnormalities have been infrequently reported to associate with clinical status. We investigated whether perfusion abnormalities correlated with seizure and clinical outcome in encephalitis. We retrospectively analyzed the MR studies of 77 pediatric patients with encephalitis. Pseudo-continuous arterial spin-labeling (ASL) imaging was performed on a 3-T scanner. The patients were divided into five groups according to ASL perfusion imaging pattern: normal perfusion (NP), focal hypoperfusion (Lf), extreme global hypoperfusion (LE), focal hyperperfusion (Hf), and extreme global hyperperfusion (HE). Clinical outcome at 3weeks was dichotomized to unfavorable or favorable outcome according to the Glasgow outcome scale. Multivariate logistic regression was conducted to predict unfavorable outcome and presence of seizure separately, based on explanatory variables including age, sex, and ASL pattern. Twenty-seven (35%) patients were designated as in group Hf, five (7%) in group Lf, 11 (14%) in group LE, none in group HE, and 34 (44%) in group NP. Multivariate logistic regression analysis showed that ASL pattern was significantly associated with unfavorable outcome (P = 0.005) and with presence of seizure (P = 0.005). For ASL pattern, group LE was 17.31 times as likely to have an unfavorable outcome as group NP (odds ratio confidence interval [CI] 3.084, 97.105; P = 0.001). Group Hf was 6.383 times as likely to have seizure as group NP (CI 1.765, 23.083; P = 0.005). In childhood encephalitis, patients with extreme global hypoperfusion had poor neurological outcome and those with focal hypoperfusion were more likely to have seizure.

Resting cerebral blood flow alterations specific to the comitant exophoria patients revealed by arterial spin labeling perfusion magnetic resonance imaging

PurposeIt has been shown in many previous studies that there were significant changes of the brain anatomy and function in strabismus. However, the significance of the alterations of resting cerebral blood flow (CBF) in comitant exophoria (CE) remains obscure. Arterial spin labeling (ASL) MRI, which is a noninvasive method, could be applied to detect the cerebral blood flow quantitatively. Our study aimed to compare the resting CBF between the comitant exophoria and health controls using pseudo-continuous arterial spin labeling (pCASL) perfusion MRI method. Methods32 patients (25 males and 7 females) with CE (study group), and 32 (25 males and 7 females) healthy individuals with matched age and sex status (control group) underwent a whole-brain pCASL magnetic resonance (MR) examination at the resting state. The resting CBF were voxel-wise compared between the two groups using an analysis of variance designed in a statistical parametric mapping program. The CE patients were distinguishable from the healthy controls (HCs) by receiver operating characteristic (ROC) curves. ResultsCompared with the control group, the CE group showed significantly increased resting CBF values in the right parahippocampal regions, bilateral medial frontal gyrus/anterior cingulate cortex, left inferior frontal gyrus, right inferior frontal gyrus, left superior frontal gyrus, bilateral medial cingulate cortex, right middle frontal gyrus, and right paracentral lobule. ConclusionComitant exophoria showed increased resting CBF in eye movement-related brain areas including supplementary eye field, cingulate eye field and frontal eye field, which could be an explanation of the brain function compensation for the ocular motility disorders in the CE patients.

Optimized super-selective Arterial Spin Labeling for quantitative flow territory mapping

Flow territory mapping using Arterial Spin Labeling (ASL) methods allows for deeper insights into the physiology of the brain. However, in most approaches assumptions of the labeling efficiency are used for calculation of brain perfusion which might result in inaccuracies. This becomes more important in super-selective ASL as the labeling focus could be positioned not exactly at the artery of interest. Therefore, measuring the labeling efficiency of the current scan seems important to obtain reliable results and to correct for potential errors. In this study, an optimized super-selective ASL tagging scheme is presented and the labeling efficiency is measured using quantitative phase-contrast angiography of the tagged artery and considering the volume of the supplied flow territory. The aim then is to evaluate the labeling efficiency of super-selective ASL and considering these values when shifting the labeling spot away from the artery of interest. The measured efficiency is compared to simulations performed for the optimized super-selective ASL approach. Considering the values of labeling efficiency after shifting the labeling focus, the values of cerebral blood flow still show accurate results despite the expected lower SNR up to an offset of 3 mm. Following this, to obtain accurate results for quantifying super-selective ASL perfusion images, measuring the labeling efficiency seems necessary to prevent false results.

Priors-guided slice-wise adaptive outlier cleaning for arterial spin labeling perfusion MRI

BackgroundDue to the low signal-to-noise-ratio (SNR) and unavoidable head motions, the pairwise subtraction perfusion signal extraction process in arterial spin labeling (ASL) perfusion MRI can produce extreme outliers. Comparison with existing methodsWe previously proposed an adaptive outlier cleaning (AOC) algorithm for ASL MRI. While it performed well even for clinical ASL data, two issues still exist. One is that if the reference is already dominated by noise, outlier cleaning using low correlation with the mean as a rejection criterion will actually reject the less noisy samples but keep the more noisy ones. The other is that it is sub-optimal to reject the entire outlier volumes without considering the quality of each constituent slices. To address both problems, a prior-guided and slice-wise AOC algorithm was proposed in this study. New MethodsThe reference of AOC was initiated to be a pseudo cerebral blood flow (CBF) map based on prior knowledge and outlier rejection was performed at each slice. ASL data from the ADNI database (www.adni-info.org) were used to validate the method. Image preprocessing was performed using ASLtbx. ResultsThe proposed method outperformed the original AOC and SCORE in terms of higher SNR and test-retest stability of the resultant CBF maps. ConclusionASL CBF can be substantially improved using prior-guided and slice-wise outlier rejection. The proposed method will benefit the ever since increasing ASL user community for both clinical and scientific brain research.

Hemodynamic state of periictal hyperperfusion revealed by arterial spin-labeling perfusion MR images with dual postlabeling delay.

BackgroundMagnetic resonance imaging (MRI), including perfusion MRI with arterial spin labeling (ASL) and diffusion-weighted imaging (DWI), are applied in the periictal detection of circulatory and metabolic consequences associated with epilepsy. Although previous report revealed that prolonged ictal hyperperfusion on ASL can be firstly detected and cortical hyperintensity of cytotoxic edema on DWI secondarily obtained from an epileptically activated cortex, the hemodynamic state of the periictal hyperperfusion has not been fully demonstrated.Methods: study-1We retrospectively analyzed the relationship between seizure manifestations and the development of periictal MRI findings, in Case 1 with symptomatic partial epilepsy, who underwent repeated periictal ASL/DWI examination for three epileptic ictuses (one examination for each ictus). Study-2: We evaluated the hemodynamic state of periictal hyperperfusion with the ASL technique using a dual postlabeling delay (PLD) of 1.5 and 2.5 s in nine patients, according to the presence or absence of the localized epileptogenic lesion (EL) on conventional 3 T-MRI, who were divided into Group EL+ (six patients) and Group EL− (three patients).ResultsStudy-1 confirmed that the stratified representation of the periictal MRI findings depends on the time interval between the ictal cessation and MRI examination in addition to the magnitude and duration of the epileptic activity. In Study-2, two types of periictal hyperperfusion were noted. In all six Group EL+ patients, periictal ASL findings showed “fast flow type”. Markedly increased ASL signals were noted at the epileptically activated cortex, having a tight topographical relationship with EL, on ASL with a PLD of 1.5 s, which is decreased on ASL with a PLD of 2.5 s. In all three Group EL− patients, periictal ASL findings showed “gradual flow type”, which is characterized by gradual signal increase of the epileptically activated cortex on ASL with a PLD of 1.5 and 2.5 s.ConclusionWe confirmed that ASL hyperperfusion is superior to DWI in the periictal detection of epileptic events. ASL with dual PLD offers the ability to document two types of hemodynamics of periictal hyperperfusion.

Cerebral Blood Flow Abnormalities in Brain Regions Responsible for Cognitive Function in Type 2 Diabetes

Aim: The risk of developing mild cognitive impairment (MCI) increases with type 2 diabetes (T2DM). Brain morphometric changes associated with MCI have been described. However Cerebral Blood Flow (CBF) changes in relation to MCI has not been fully investigated. This study aims to investigate regional CBF changes in subjects with T2DM and MCI. Method: Seventy-four age and gender matched subjects [28, T2DM (T2DM); 17, T2DM+MCI (T2DM/MCI) and 29, healthy volunteers (HV)] were recruited. All subjects underwent clinical and questionnaire (Addenbrooke’s Cognitive Assessment [ACE-R]) assessment along with Arterial Spin Labelling (ASL) perfusion Magnetic Resonance Imaging (MRI) of the brain. The ASL data was modelled to yield quantitative arterial CBF maps in neuroanatomical regions involved with cognitive function. Results: Demographic data revealed aged-matched participants between all three groups (mean age 69.3-71.5 years, ANOVA, p = 0.164). Mean age of last education was significantly lower in the T2DM/MCI group (mean±SD;15.1 ±0.9 when compared to the other groups (HV 19.3±5.6, T2DM 17.1±2.9) Kruskal-Wallis, p=0.003. T2DM/MCI ACE-R score (mean±SD; 83±4) was significantly lower compared to other groups (HV=96±2, T2DM=94±3; ANOVA p&amp;lt;0.001). There was significantly lower CBF in T2DM/MCI compared to T2DM and HV in the medial temporal lobes (CBF 76.8 ml/100g/min, ANOVA p&amp;lt;0.05), insula (CBF 67.5 ml/100g/min ANOVA p&amp;lt;0.005), and frontal lobes (CBF 71.8 ml/100g/min, ANOVA p&amp;lt;0.005)&amp;lt;bold&amp;gt;. &amp;lt;/bold&amp;gt;Pearson’s correlation revealed significant correlations between ACE-R score and regional CBF measurements in the medial temporal lobes, (p&amp;lt;0.05, r=.25) thalamus (p&amp;lt;0.05, r=.23) and insula (p&amp;lt;0.05, r=.29). Conclusion: This study demonstrates significantly lower CBF in T2DM MCI subjects in neuroanatomical regions responsible for cognitive function. This may be essential to help understand the pathological mechanisms that occur behind the increased risk of developing cognitive impairment in T2DM. Disclosure L. Hunt: None. D. Selvarajah: None. S. Tesfaye: Speaker's Bureau; Self; Pfizer Inc.. Other Relationship; Self; Janssen Pharmaceuticals, Inc., Takeda Development Centre Europe Ltd.. Advisory Panel; Self; Wörwag Pharma GmbH &amp; Co. KG. I.D. Wilkinson: None.

Arterial spin labeling perfusion: Prospective MR imaging in differentiating neoplastic from non-neoplastic intra-axial brain lesions.

The purpose of this article is to assess the diagnostic performance of arterial spin-labeling (ASL) magnetic resonance perfusion imaging to differentiate neoplastic from non-neoplastic brain lesions. This prospective study included 60 consecutive, newly diagnosed, untreated patients with intra-axial lesions with perilesional edema (PE) who underwent clinical magnetic resonance imaging including ASL sequences at 3T. Region of interest analysis was performed to obtain mean cerebral blood flow (CBF) values from lesion (L), PE and normal contralateral white matter (CWM). Normalized (n) CBF ratio was obtained by dividing the mean CBF value of L and PE by mean CBF value of CWM. Discriminant analyses were performed to determine the best cutoff value of nCBFL and nCBFPE in differentiating neoplastic from non-neoplastic lesions. Thirty patients were in the neoplastic group (15 high-grade gliomas (HGGs), 15 metastases) and 30 in the non-neoplastic group (12 tuberculomas, 10 neurocysticercosis, four abscesses, two fungal granulomas and two tumefactive demyelination) based on final histopathology and clincoradiological diagnosis. We found higher nCBFL (6.65 ± 4.07 vs 1.68 ± 0.80, p < 0.001) and nCBFPE (1.86 ± 1.43 vs 0.74 ± 0.21, p < 0.001) values in the neoplastic group than non-neoplastic. For predicting neoplastic lesions, we found an nCBFL cutoff value of 1.89 (AUC 0.917; 95% CI 0.854 to 0.980; sensitivity 90%; specificity 73%) and nCBFPE value of 0.76 (AUC 0.783; 95% CI 0.675 to 0.891; sensitivity 80%; specificity 58%). Mean nCBFL was higher in HGGs (8.70 ± 4.16) compared to tuberculomas (1.98 ± 0.87); and nCBFPE was higher in HGGs (3.06 ± 1.53) compared to metastases (0.86 ± 0.34) and tuberculomas (0.73 ± 0.22) ( p < 0.001). ASL perfusion may help in distinguishing neoplastic from non-neoplastic brain lesions.

Transient Neurologic Deficit without Vascular Pathology Correlates with Reversible Focal Hypoperfusion on Arterial Spin Labeled Perfusion Imaging

AbstractWe present the case of a 16-year-old boy with altered mental status and magnetic resonance imaging demonstrating left hemispheric hypoperfusion without evidence of stroke, based on arterial spin labeling (ASL) and dynamic contrast-enhanced perfusion imaging. Vessel imaging on magnetic resonance angiography and computed tomography angiography, in addition to an echocardiogram, showed no evidence of an embolic source. Electroencephalography showed left posterior temporal slowing. Within 8 hours, he was awake and alert but with receptive aphasia, and within 24 hours his symptoms completely resolved. Repeat ASL perfusion imaging demonstrated complete resolution of the perfusion abnormality, and diffusion imaging revealed no areas of infarct. This report demonstrates the correlation between a transient neurologic deficit and reversible focal hypoperfusion measured by ASL cerebral perfusion.

Noninvasive method for measurement of cerebral blood flow using O-15 water PET/MRI with ASL correlation

PurposeA noninvasive image derived input function (IDIF) method was applied to estimate arterial input function from brain H215O-PET/MRI images for the measurement of cerebral blood flow (CBF) because of difficulty in arterial blood sampling during PET/MRI scans. To evaluate accuracy and reproducibility of radioactivity in the internal carotid arteries (ICA) for the IDIF method, a new phantom using a skull bone was applied in the cross-calibration process between the scanner and a gamma-well counter. MethodsEleven healthy volunteers (9 males, 43.9 ± 10.9y) underwent PET/MRI studies with a 3-min H215O-PET and several MRI scans including arterial spin labeling (ASL) perfusion MRI. PET images were reconstructed as dynamic data using two sets of reconstruction parameters, which were determined by basic assessment of radioactivity concentration reproducibility in the tubes of the phantom. The IDIF method extracted the time-activity curves of the ICA from several image slices in the PET data. CBF images were calculated using the autoradiographic (ARG) method and a one-tissue compartment model (1-TCM). ResultsThe global means of CBF from the ARG, 1-TCM, and ASL-MRI were 44.8 ± 4.3, 47.9 ± 5.9 and 57.9 ± 8.6 (mL/min/100 g), respectively. CBF from ASL-MRI was significantly greater compared with CBF from H215O-PET (P < 0.001). However, these CBF values were significantly correlated with each other in the scatter plots (P < 0.05). ConclusionsNoninvasive measurement of CBF using H215O-PET/MRI and IDIF with the cross-calibration method with a skull phantom experiment provided reasonable quantitative values. The IDIF method allowed reliable estimation of arterial radioactivity concentration, which is useful for clinical application. The ASL-MRI perfusion image from the simultaneous acquisition tended to overestimate CBF.

The combined application of magnetic resonance DTI and 3D-pcASL in differential diagnosis of hyper-acute and acute ischemic cerebral infarction

Objective: To explore the clinical value of magnetic resonance diffusion tensor imaging (DTI) combined with 3D pseudo continuous arterial spin labeling (3D-pcASL) perfusion imaging in differential diagnosis of hyper-acute and acute ischemic cerebral infarction. Methods: A total of 42 patients with confirmed unilateral ischemic cerebral infarction from February 2015 to October 2017 of Affiliated Yancheng Hospital of Southeast University Medical College were collected. DTI and 3D-pcASL images of hyper-acute (14 patients, group A) and acute (28 patients, group B) ischemic cerebral infarction were retrospectively analyzed. The slice with the biggest lesion on diffusion weighted imaging (DWI) was selected to measure the infarction area (S(DWI)) and abnormal cerebral blood flow (CBF) perfusion area (S(CBF)). Regions of interest (ROIs) were set on the infarction core (IC) area, mismatch area of S(CBF) and S(DWI) (MACD), and their corresponding contralateral regions. The values of CBF, average diffusion coefficient (DC(avg)), and fractional anisotropy (FA) parameter images in these ROIs in patients with both S(CBF)>S(DWI) and lower perfusion in the IC were recorded. The relative values of each infarction lesion to its corresponding contralateral region (rCBF, rFA, and rDC(avg)) were calculated. Differences of each parameter value between the IC, MACD and their corresponding contralateral regions and of the relative values between group A and group B were investigated. Results: The CBF and DC(avg) values in the IC and the CBF value in the MACD were lower than that of their corresponding contralateral regions in both groups (P<0.05). The DC(avg) in the MACD in group A patients and the FA in the IC in group B patients were lower than that in their corresponding contralateral regions (P<0.05). Compared to group A patients, group B patients showed decreased rFA, rDC(avg) in the IC and rFA in the MACD, and increased rDC(avg) and rCBF in the MACD (P<0.05). Receiver operating characteristics (ROC) curve analysis indicated that the best diagnosis cut off values of the rFA and rDC(avg) values in the IC and the rCBF, rFA, and rDC(avg) values in the MACD were 0.890 and 0.541 and 1.139, 0.902 and 0.455, respectively, for identifying two groups. Conclusion: The changes of the CBF, FA, and DC(avg) values and their relative values can be applied to differentially diagnose patients with hyper-acute and acute cerebral infarction, which could provide the basis for selecting more reasonable treatment protocols.