3D Pseudo-continuous Arterial Spin Labeling Research Articles

Altered cerebral neurovascular coupling in medication-overuse headache: A study combining multi-modal resting-state fMRI with 3D PCASL.

Structural and functional changes in the brain have been identified in individuals with medication-overuse headache (MOH) using MRI. However, it has not been clearly established whether neurovascular dysfunction occurs in MOH, which could be elucidated by examining neurovascular coupling (NVC) from the viewpoints of neuronal activity and cerebral blood flow. The aim of this study was to investigate potential alterations in NVC function of the brain in individuals with MOH using resting-state functional MRI (rs-fMRI) and 3D pseudo-continuous arterial spin labeling (3D PCASL) imaging techniques. A total of 40 patients with MOH and 32 normal controls (NCs) were recruited, and rs-fMRI and 3D PCASL data were obtained using a 3.0 T MR scanner. Standard preprocessing of the rs-fMRI data was performed to generate images representing regional homogeneity (ReHo), fractional amplitude of low-frequency fluctuation (fALFF), and degree centrality (DC); cerebral blood flow (CBF) images were generated using 3D PCASL sequence data. These functional maps were all normalized into Montreal Neurological Institute (MNI) space, and NVC was subsequently determined on the basis of Pearson correlation coefficients between the rs-fMRI maps (ReHo, fALFF, and DC) and CBF maps. The statistical significance of differences between the MOH and NC groups in terms of NVC in different brain regions was established via Z-test. Further analysis was performed to examine correlations between NVC in the brain regions with NVC dysfunction and clinical variables among patients with MOH. NVC mainly presented a negative correlation in patients with MOH and NCs. No significant difference between the two groups was detected in terms of average NVC over the entire gray matter area. However, several brain regions with significantly decreased NVC in patients with MOH compared to NCs were identified: the left orbital region of the superior frontal gyrus, the bilateral gyrus rectus, and the olfactory cortex (P < 0.05). A correlation analysis revealed that the DC of the brain regions with NVC dysfunction was significantly positively correlated with disease duration (r = 0.323, P = 0.042), and DC-CBF connectivity was negatively correlated with VAS score (r = -0.424, P = 0.035). The current study demonstrated that cerebral NVC dysfunction occurs in patients with MOH, and the NVC technique could function as a new imaging biomarker in headache research.

Blood flow perfusion in visual pathway detected by arterial spin labeling magnetic resonance imaging for differential diagnosis of ocular ischemic syndrome.

Ocular ischemic syndrome (OIS), attributable to chronic hypoperfusion caused by marked carotid stenosis, is one of the important factors that cause ocular neurodegenerative diseases such as optic atrophy. The current study aimed to detect blood flow perfusion in a visual pathway by arterial spin labeling (ASL) and magnetic resonance imaging (MRI) for the differential diagnosis of OIS. This diagnostic, cross-sectional study at a single institution was performed to detect blood flow perfusion in a visual pathway based on 3D pseudocontinuous ASL (3D-pCASL) using 3.0T MRI. A total of 91 participants (91 eyes) consisting of 30 eyes with OIS and 61 eyes with noncarotid artery stenosis-related retinal vascular diseases (39 eyes with diabetic retinopathy and 22 eyes with high myopic retinopathy) were consecutively included. Blood flow perfusion values in visual pathways derived from regions of interest in ASL images, including the retinal-choroidal complex, the intraorbital segments of the optic nerve, the tractus optics, and the visual center, were obtained and compared with arm-retinal circulation time and retinal circulation time derived from fundus fluorescein angiography (FFA). Receiver operating characteristic (ROC) curve analyses and the intraclass correlation coefficient (ICC) were performed to evaluate the accuracy and consistency. Patients with OIS had the lowest blood flow perfusion values in the visual pathway (all p < 0.05). The relative intraorbital segments of optic nerve blood flow values at post-labeling delays (PLDs) of 1.5 s (area under the curve, AUC = 0.832) and the relative retinal-choroidal complex blood flow values at PLDs of 2.5 s (AUC = 0.805) were effective for the differential diagnosis of OIS. The ICC of the blood flow values derived from the retinal-choroidal complex and the intraorbital segments of the optic nerve between the two observers showed satisfactory concordance (all ICC > 0.932, p < 0.001). The adverse reaction rates of ASL and FFA were 2.20 and 3.30%, respectively. 3D-pCASL showed that the participants with OIS had lower blood flow perfusion values in the visual pathway, which presented satisfactory accuracy, reproducibility, and safety. It is a noninvasive and comprehensive differential diagnostic tool to assess blood flow perfusion in a visual pathway for the differential diagnosis of OIS.

Comparative study between dynamic susceptibility contrast magnetic resonance imaging and arterial spin labelling perfusion in differentiating low-grade from high-grade brain tumours.

Our aim was to distinguish between low-grade and high-grade brain tumours on the basis of dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) perfusion and arterial spin labelling (ASL) perfusion and to compare DSC and ASL techniques. Forty-one patients with brain tumours were evaluated by 3-Tesla MRI. Conventional and perfusion MRI imaging with a 3D pseudo-continuous ASL (PCASL) and DSC perfusion maps were evaluated. Three ROIs were placed to obtain cerebral blood value (CBV) and cerebral blood flow (CBF) in areas of maximum perfusion in brain tumour and normal grey matter. Histopathological diagnosis was considered as the reference. ROC analysis was performed to compare the diagnostic performance and to obtain a feasible cut-off value of perfusion parameters to differentiate low-grade and high-grade brain tumours. Normalised perfusion parameters with grey matter (rCBF or rCBV lesion/NGM) of malignant lesions were significantly higher than those of benign lesions in both DSC (normalised rCBF of 2.16 and normalised rCBV of 2.63) and ASL (normalised rCBF of 2.22) perfusion imaging. The normalised cut-off values of DSC (rCBF of 1.1 and rCBV of 1.4) and ASL (rCBF of 1.3) showed similar specificity and near similar sensitivity in distinguishing low-grade and high-grade brain tumours. Quantitative analysis of perfusion parameters obtained by both DSC and ASL perfusion techniques can be reliably used to distinguish low-grade and high-grade brain tumours. Normalisation of these values by grey matter gives us more reliable parameters, eliminating the different technical parameters involved in both the techniques.

Sex-dependent changes in emotional memory associated with cerebral blood flow alterations during Alzheimer's disease progression.

Sex differences in Alzheimer's disease (AD) progression provide clues to pathogenesis and better patient management. We examined sex differences in emotional memory among AD patients, amnesticmild cognitive impairment (aMCI) patients, and healthy controls (HCs) as well as potential associations with altered regional cerebral blood flow (rCBF). The recognition memory task with emotional pictures was applied to evaluate enhancement of emotional memory (EEM) and 3D pseudo-continuous arterial spin labeling MRI was performed to measure the rCBF in 74 AD patients (41 females), 74 aMCI patients (45 females), and 74 HCs (43 females). Group differences in EEM were tested by two-way analysis of covariance (ANCOVA) with repeated measures. The main effects of clinical group and sex as well as group × sex interactions on rCBF were assessed by two-way ANCOVA. Correlation analyses were conducted to investigate associations between EEM and rCBF. With disease progression, EEM gradually disappeared. Among aMCI patients, females exhibited a greater index of recollection (Pr) for positive/high-arousal and negative/low-arousal pictures versus neutral pictures (P = 0.005, P = 0.003), while males exhibited a greater Pr for negative/high-arousal versus neutral pictures (P = 0.001). There were significant sex × group effects on rCBF in left inferior parietal, supramarginal, superior temporal and middle temporal gyri, and rCBF of left inferior parietal gyrus was correlated with Pr for positive/high-arousal pictures among female aMCI patients (r = 0.584, q = 0.005). Males and females exhibit distinct changes in EEM associated with altered rCBF, which should be considered in future neuroimaging studies.

Lateralization of cerebral blood flow in the auditory cortex of patients with idiopathic tinnitus and healthy controls: An arterial spin labeling study.

To assess the lateralization of cerebral blood flow (CBF) in the auditory cortex of idiopathic tinnitus patients and healthy controls (HCs) using 3D pseudocontinuous arterial spin labeling (pcASL). Thirty-six patients with idiopathic tinnitus and 43 sex- and age-matched HCs underwent 3D-pcASL scanning using a 3.0 T MRI system. For both groups, region of interest analysis was performed on the primary auditory cortex (PAC), auditory associative cortex (AAC), and secondary auditory cortex (SAC). The clinical data of all subjects were analyzed. In both tinnitus patients and HCs, CBF of the left PAC was significantly higher than that of the right (HCs: P = 0.02; patients: P = 0.043), but CBF of the right AAC and SAC was significantly higher than that of the left (AAC: HCs, P < 0.001; patients: P < 0.001. SAC: HCs, P < 0.001; patients: P = 0.001). Compared with HCs, tinnitus patients exhibited significantly higher CBF in the bilateral PAC (right: P = 0.008; left: P = 0.022). CBF in the left PAC was positively correlated with tinnitus severity (r = 0.399, P = 0.016). This study confirms the asymmetry of the auditory cortex and investigates the underlying neuropathology of idiopathic tinnitus in terms of CBF.

The effect of dobutamine on ocular blood flow of healthy adults: A 3D pseudocontinuous aterial spin labelling study.

Purpose: Ocular blood flow (OBF) is an important risk factor for incidence, prevalence and progression of some ocular disorders. To date, there are very limited therapeutic options to increase OBF. This study investigated the effect of dobutamine on OBF of heathy adults using 3D pseudocontinuous arterial spin labelling (3D-pcASL), and explored the risk factors associated with OBF. Methods: Forty-three healthy participants (86 eyes) were given an intravenous injection of dobutamine. We measured OBF using 3D-pcASL with a 3.0T- MRI scanner, OBF values were independently obtained by two doctors from the OBF map. We also collected physiological parameters using a vital signs monitor. The OBF and physiological parameters in the in the period before and after dobutamine injection states were obtained. Results: OBF increased significantly after dobutamine injection using paired t test method (from 22.43 ± 9.87 to 47.73 ± 14.02ml/min/100g, p < 0.001). Age, heart rate and systolic blood pressure were the main risk factors affecting OBF using logistic regression analysis (all p values < 0.05). Conclusion: To the best of our knowledge, this is the first study observing the effect of dobutamine on OBF. Our findings indicated that intravenously injected dobutamine increased OBF, making it a possible option to counteract ocular vascular ischaemia in the future.

Altered Cerebral Blood Flow is Linked to Disease Duration in Patients with Generalized tonic‒clonic Seizures

To investigate cerebral blood flow (CBF) characteristics in individuals with generalized tonic‒clonic seizures (GTCS) during theinterictalphase using voxel-based analysis of 3D pseudocontinuous arterial spin labeling (PCASL). Patients with GTCS (GTCS group) (during the interictal period) and healthy volunteers (control group) underwent head MR imaging with a 3.0T MR scanner with a 3D PCASL sequence. CBF was compared between the two groups. Spearman correlations of CBF in regions of interest (ROIs) in GTCS patients with the duration of disease and age of onset were analyzed and corrected using the false discovery rate (FDR). Twenty patients with GTCS (GTCS group) and twenty healthy volunteers (control group) were recruited for this study. On 3D PCASL, (1) GTCS patients had lower CBF in the brainstem, right cerebellum, right inferior temporal gyrus, parahippocampal gyrus, superior frontal gyrus, middle frontal gyrus, triangular part of inferior frontal gyrus, left temporal pole of superior temporal gyrus and thalamus and had higher CBF in the bilateral superior parietal gyri, precuneus, precentral gyri, postcentral gyri, and left dorsolateral superior frontal gyrus than controls. (2) The CBF of the right temporal pole of the middle temporal gyrus was negatively correlated with the duration of disease (PFDRcorrected<0.05), with a correlation coefficient r of -0.7333 and a PFDRcorrected value of 0.04. Voxel-based analysis of3D PCASL imaging can be used to sensitively detect brain perfusion differences in GTCS patients. The decrease in CBF in the right temporal pole of the middle temporal gyrus may be associated with disease onset. These findings may offer new perspectives on the pathogenesis of GTCS and the underlying pathophysiological changes associated with perfusion.

Differentiation of true progression from treatment response in high-grade glioma treated with chemoradiation: a comparison study of 3D-APTW and 3D-PcASL imaging and DWI.

To assess and compare the diagnostic performance of 3D amide proton-transfer-weighted (3D-APTW) imaging, 3D pseudocontinuous arterial spin-labeling (3D-PcASL) imaging, and diffusion-weighted imaging in distinguishing true progression (TP) from treatment response (TR) in posttreatment malignant glioma patients. Forty-eight patients with suspected tumor recurrence were prospectively enrolled. Histological or longitudinal routine MRI follow-up over six months was assessed to confirm lesion type. The apparent diffusion coefficient (ADC), relative APTWmax (rAPTW), and relative CBFmax values (rCBF) were measured in lesions with enhancing regions on post-gadolinium T1 -weighted MRI. MRI parameters between the TP and TR groups were compared using Student's t tests. In addition, a receiver operating characteristic (ROC) curve was constructed, and the area under the ROC curve (AUC) was calculated to assess the differentiation diagnostic performance of each parameter. The TP group showed a significantly higher rAPTW and rCBF than the TR group; the AUCs of rAPTW and rCBF to distinguish between TP and TR were 0.911 (with sensitivity of 90.3% and specificity of 82.4%) and 0.852 (with sensitivity of 80.6% and specificity of 82.4%), respectively. By adding the rAPTW values to rCBF values, the diagnostic ability was improved from 0.852 to 0.951. ADC showed no significant differences between the TP and TR groups, with an AUC lower than 0.70. Both 3D-PcASL and 3D-APTW imaging could distinguish TP from TR, and 3D-APTW had a better diagnostic performance. Combining the rAPTW values and rCBF values achieved a better diagnostic performance.

3D Amide Proton Transfer-Weighted Imaging for Grading Glioma and Correlating IDH Mutation Status: Added Value to 3D Pseudocontinuous Arterial Spin Labelling Perfusion.

The goal of this study was to evaluate the diagnostic performance of 3D amide proton transfer-weighted (3D-APTW) imaging and 3D pseudocontinuous arterial spin labelling (3D-pCASL) alone and in combination in grading gliomas (low-grade glioma (LGG) vs. high-grade glioma (HGG)) and correlating isocitrate dehydrogenase (IDH) mutation status. Preoperatively, 81 patients with pathologically confirmed gliomas underwent 3.0-T magnetic resonance imaging (MRI) examinations. The APTW, relative APTW (rAPTW), cerebral blood flow (CBF), and relative CBF (rCBF) values were calculated to evaluate the solid components of the tumours. The MRI parameters were compared in the classification of gliomas by independent- and paired-samples t tests. A receiver operating characteristic (ROC) curve was constructed, and the area under the ROC curve (AUC) was calculated to assess the diagnostic performance of each parameter and the combination of the rAPTW and rCBF values. Patients with HGG showed significantly higher APTW, rAPTW, CBF, and rCBF values than those with LGG (all p < 0.001). In the ROC curve analysis, the AUC of rAPTW was the highest at 0.90. By adding the rAPTW signal to the rCBF values, the diagnostic ability of the combined parameters improved from 0.90 to 0.96. The rAPTW value yielded the highest AUC (0.92) in correlating the IDH mutation status, and the diagnostic ability improved to 0.96 by adding it to the rCBF value. 3D-APTW imaging combined with 3D-pCASL imaging may be used to aid assessment of grading glioma and IDH mutation status.

Arterial Spin Labeling Imaging Characteristics of Anti-leucine-rich Glioma-Inactivated 1 Encephalitis: A Qualitative and Quantitative Analysis.

Background and SignificanceAutoimmune encephalitis (AE) is a rare group of diseases that can present with stroke-like symptoms. Anti-leucine-rich glioma inactivated 1 (LGI1) encephalitis is an AE subtype that is infrequently associated with neoplasms and highly responsive to prompt immunotherapy treatment. Therefore, accurate diagnosis of LGI1 AE is essential in timely patient management. Neuroimaging plays a critical role in evaluating stroke and stroke mimics such as AE. Arterial Spin Labeling (ASL) is an MRI perfusion modality that measures cerebral blood flow (CBF) and is increasingly used in everyday clinical practice for stroke and stroke mimic assessment as a non-contrast sequence. Our goal in this preliminary study is to demonstrate the added value of ASL in detecting LGI1 AE for prompt diagnosis and treatment.MethodsIn this retrospective single center study, we identified six patients with seropositive LGI1 AE who underwent baseline MRI with single delay 3D pseudocontinuous ASL (pCASL), including five males and one female between ages 28 and 76 years, with mean age of 55 years. Two neuroradiologists qualitatively interpreted the ASL images by visual inspection of CBF using a two-point scale (increased, decreased) when compared to both the ipsilateral and contralateral unaffected temporal and non-temporal cortex. The primary measures on baseline ASL evaluation were a) presence of ASL signal abnormality, b) if present, signal characterization based on the two-point scale, c) territorial vascular distribution, d) localization, and e) laterality. Quantitative assessment was also performed on postprocessed pCASL cerebral blood flow (CBF) maps. The obtained CBF values were then compared between the affected temporal cortex and each of the unaffected ipsilateral parietal, contralateral temporal, and contralateral parietal cortices.ResultsOn consensus qualitative assessment, all six patients demonstrated ASL hyperperfusion and corresponding FLAIR hyperintensity in the hippocampus and/or amygdala in a non-territorial distribution (6/6, 100%). The ASL hyperperfusion was found in the right hippocampus or amygdala in 5/6 (83%) of cases. Four of the six patients underwent initial follow-up imaging where all four showed resolution of the initial ASL hyperperfusion. In the same study on structural imaging, all four patients were also diagnosed with mesial temporal sclerosis (MTS). Quantitative assessment was separately performed and demonstrated markedly increased CBF values in the affected temporal cortex (mean, 111.2 ml/min/100 g) compared to the unaffected ipsilateral parietal cortex (mean, 49 ml/min/100 g), contralateral temporal cortex (mean, 58.2 ml/min/100 g), and contralateral parietal cortex (mean, 52.2 ml/min/100 g).DiscussionIn this preliminary study of six patients, we demonstrate an ASL hyperperfusion pattern, with a possible predilection for the right mesial temporal lobe on both qualitative and quantitative assessments in patients with seropositive LGI1. Larger scale studies are necessary to further characterize the strength of these associations.

The Diagnostic Value of the Combined 3D Pseudo-Continuous Arterial Spin Labeling and Diffusion Kurtosis Imaging in Patients With Binswanger's Disease.

Background and PurposeThe clinical diagnosis of Binswanger’s disease (BD), a chronic progressive form of subcortical vascular dementia, remains challenging. 3D pseudo-continuous arterial-spin-labeling (pcASL) and diffusion kurtosis imaging (DKI) can quantitatively reveal the microcirculation changes and heterogeneity of white matter (WM), respectively. We thus aimed to determine the diagnostic value of the combined 3D-pcASL and DKI in BD.Materials and MethodsA total of 35 patients with BD and 33 healthy controls underwent 3D-ASL and DKI experiments. The perfusion parameter of cerebral blood flow (CBF), diffusion parameters of fractional anisotropy (FA), mean/axial/radial diffusivity (MD/Da/Dr), and kurtosis parameters of anisotropy fraction of kurtosis (FAk) and mean/axial/radial kurtosis MK/Ka/Kr were obtained to quantitatively measure the parametric distributions of functional brain subregions. One-way analysis of variance and post hoc t-test were applied to explore the different distributions of DKI/ASL-derived parameters among brain subregions of BD. In addition, all region-specific DKI/ASL parameters were separately analyzed in Pearson correlation analysis to investigate the relationship with Mini-Mental State Examination (MMSE), a typical clinical scale for cognitive function assessment in patients with BD.ResultsFA/FAk/MK/Ka/Kr was significantly declined in all WM hyperintensities (WMHs) of BD compared with healthy controls, while the corresponding MD/Da/Dr was significantly increased (all p < 0.005). In addition, significant changes, similar to the WMHs of patients with BD, were also observed in almost all DKI parameters in WM normal areas and genu/splenium of the corpus callosum (GCC/SCC) in BD (p < 0.005). Finally, CBF was significantly reduced in all of the above regions we measured in patients with BD (p < 0.005). For patients with BD, MMSE showed a negative correlation with MD/Da in thalamus (r = −0.42/−0.58; p < 0.05), and a positive correlation with CBF in PWM/TWM (r = 0.49/0.39; p < 0.05). Using receiver operating characteristic (ROC) analysis, FA/FAk/Kr in GCC, CBF/FA/Dr/FAk in SCC, MD/Da/Ka in thalamus, and the combined FA/MD/Dr/CBF in TWM showed high accuracy [area under the curves (AUCs) 0.957/0.946/0.942/0.986] in distinguishing patients with BD from healthy controls.ConclusionWe found that combined DKI and 3D-ASL are helpful in diagnosing patients with BD, especially with FA, MD, Dr, and CBF in the temporal WM region. Additionally, the kurtosis parameters of DKI can sensitively monitor the potentially damaged WM areas in patients with BD patients, adding complementary clinical value.

Hypoperfusion in nucleus accumbens in chronic migraine using 3D pseudo-continuous arterial spin labeling imaging MRI

BackgroundNucleus accumbens (NAcc) played an important role in pain mediation, and presents changes of neuronal plasticity and functional connectivity. However, less is known about altered perfusion of NAcc in chronic migraine (CM). The aim of this study is to investigate the altered perfusion of the NAcc in CM using a MR three-dimensional pseudo-continuous arterial spin labeling (3D PCASL) imaging.MethodsThirteen CM patients and 15 normal controls (NC) were enrolled and underwent 3D PCASL and brain structural imaging. The cerebral blood flow (CBF) images were co-registered with the brain structural images, and the volume and CBF value of NAcc were extracted from the raw brain structural images and co-registered CBF images using an individual NAcc mask, which was obtained from the AAL3 template under transformation by the inverse deformation field generated from the segmentation of the brain structural images. The independent sample t test and receiver operating characteristic (ROC) curve was used to investigate the altered volume and perfusion of the NAcc in CM patients.ResultsThere was no significant difference for the volume of bilateral NAccs between CM and NC (p > 0.05). CM presented a lower CBF value (49.34 ± 6.09 ml/100 mg/min) compared with that of NC (55.83 ± 6.55 ml/100 mg/min) in left NAcc (p = 0.01), while right NAcc showed no significant difference between CM and NC (p = 0.11). ROC analysis identified that the area under the curve was 0.73 (95CI% 0.53–0.88) with cut-off value 48.63 ml/100 mg/min with sensitivity 50.00% and specificity 93.33%. The correlation analysis found a negative correlation between the CBF value of the left NAcc and VAS score (r = -0.61, p = 0.04).ConclusionHypoperfusion of the left NAcc was observed in CM, which could be considered as a potential diagnostic imaging biomarker in CM.

Arterial Spin Labeling Perfusion in Determining the IDH1 Status and Ki-67 Index in Brain Gliomas.

The aim of the study was to evaluate the relationship between tumor blood flow (TBF) measured by the pseudo-continuous arterial spin labeling (PCASL) method and IDH1 mutation status of gliomas as well as Ki-67 proliferative index. Methods. The study included 116 patients with newly diagnosed gliomas of various grades. They received no chemotherapy or radiotherapy before MRI. IDH1 status assessment was performed after tumor removal in 106 cases—48 patients were diagnosed with wildtype gliomas (Grade 1–2—6 patients, Grade 3–4—42 patients) and 58 patients were diagnosed with mutant forms of gliomas (Grade 1–2—28 patients, Grade 3–4—30 patients). In 64 cases out of 116 Ki-67 index was measured. Absolute and normalized tumor blood flow values were measured on 3D PCASL maps. Results. TBF and normalized TBF (nTBF) in wildtype gliomas were significantly higher than in IDH1-mutant gliomas (p < 0.001). ASL perfusion showed high values of sensitivity and specificity in the differential diagnosis of gliomas with distinct IDH1 status (for TBF: specificity 75%, sensitivity 77.6%, AUC 0.783, cutoff 80.57 mL/100 g/min, for nTBF: specificity 77.1%, sensitivity 79.3%, AUC 0.791, cutoff 4.7). TBF and nTBF in wildtype high-grade gliomas (HGG) were significantly higher than in mutant forms (p < 0.001). ASL perfusion showed the following values of sensitivity and specificity in the diagnosis of mutant HGG and wildtype HGG (for TBF: specificity 83.3%, sensitivity 60%, AUC 0.719, cutoff 84.18 mL/100 g/min, for nTBF: specificity 88.1%, sensitivity 60%, AUC 0.729, cutoff 4.7). There was a significant positive correlation between tumor blood flow and Ki-67 (for TBF Rs = 0.63, for nTBF Rs = 0.61). Conclusion. ASL perfusion may be an informative factor in determining the IDH1 status in brain gliomas preoperative and tumor proliferative activity.

Towards free breathing 3D ASL imaging of the human liver using prospective motion correction.

Measurements of liver perfusion yield valuable information about certain diseases like carcinomas and cirrhosis. To assess perfusion, noninvasive arterial spin labeling (ASL) MRI has the potential to become an important alternative to contrast agent-based methods. Unfortunately, ASL perfusion-weighted images are highly susceptible to breathing motion. This work presents a prospective motion-compensation technique, tackling breathing motion during ASL experiments of the human liver. Feasibility of 3D pseudo-continuous ASL imaging under free breathing is investigated by using a prospective motion-compensation technique with fat signal in additional 2D-EPI navigators. The proposed technique is compatible with strong signal suppression, occurring in background-suppressed pseudo-continuous ASL imaging. An additional retrospective 2D elastic registration algorithm is proposed to correct for residual elastic deformations. The technique is validated in 8 healthy volunteers. The prospective technique allowed a significant reduction of the cranial-caudal liver shifts during free breathing pseudo-continuous ASL experiments. Additional 2D elastic image registration allowed reduction of cranial-caudal liver motion to levels of timed breathing protocols. Artifacts in perfusion-weighted images could be reduced when compared with free-breathing ASL images without motion correction. The proposed technique is suitable for prospective compensation of liver motion in background-suppressed 3D pseudo-continuous ASL imaging. Future work focuses on further improving the quality of perfusion-weighted images.

Brain Perfusion Alterations on 3D Pseudocontinuous Arterial Spin-Labeling MR Imaging in Patients with Autoimmune Encephalitis: A Case Series and Literature Review.

Autoimmune encephalitis is a heterogeneous group of newly identified disorders that are being diagnosed with increasing frequency. Early recognition and treatment of autoimmune encephalitis are crucial for patients, but diagnosis remains challenging and time-consuming. In this retrospective case series, we describe the findings of conventional MR imaging and 3D pseudocontinuous arterial spin-labeling in patients with autoimmune encephalitis confirmed by antibody testing. All patients with autoimmune encephalitis showed increased CBF in the affected area, even when some of them presented with normal or slightly abnormal findings on conventional MR imaging. Additionally, serial 3D pseudocontinuous arterial spin-labeling showed perfusion reduction in 1 patient after therapy. For patients with highly suspected autoimmune encephalitis, 3D pseudocontinuous arterial spin-labeling may be added to the clinical work-up. Further studies and longitudinal data are needed to corroborate whether and to what extent 3D pseudocontinuous arterial spin-labeling improves the diagnostic work-up in patients with autoimmune encephalitis compared with conventional MR imaging.

The Spatiotemporal Evolution of MRI-Derived Oxygen Extraction Fraction and Perfusion in Ischemic Stroke.

PurposeThis study aimed to assess the spatiotemporal evolution of oxygen extraction fraction (OEF) in ischemic stroke with a newly developed cluster analysis of time evolution (CAT) for a combined quantitative susceptibility mapping and quantitative blood oxygen level-dependent model (QSM + qBOLD, QQ).MethodOne hundred and fifteen patients in different ischemic stroke phases were retrospectively collected for measurement of OEF of the infarcted area defined on diffusion-weighted imaging (DWI). Clinical severity was assessed using the National Institutes of Health Stroke Scale (NIHSS). Of the 115 patients, 11 underwent two longitudinal MRI scans, namely, three-dimensional (3D) multi-echo gradient recalled echo (mGRE) and 3D pseudo-continuous arterial spin labeling (pCASL), to evaluate the reversal region (RR) of the initial diffusion lesion (IDL) that did not overlap with the final infarct (FI). The temporal evolution of OEF and the cerebral blood flow (CBF) in the IDL, the RR, and the FI were assessed.ResultsCompared to the contralateral mirror area, the OEF of the infarcted region was decreased regardless of stroke phases (p < 0.05) and showed a declining tendency from the acute to the chronic phase (p = 0.022). Five of the 11 patients with longitudinal scans showed reversal of the IDL. Relative oxygen extraction fraction (rOEF, compared to the contralateral mirror area) of the RR increased from the first to the second MRI (p = 0.044). CBF was about 1.5-fold higher in the IDL than in the contralateral mirror area in the first MRI. Two patients showed penumbra according to the enlarged FI volume. The rOEF of the penumbra fluctuated around 1.0 at earlier scan times and then decreased, while the CBF decreased continuously.ConclusionThe spatiotemporal evolution of OEF and perfusion in ischemic lesions is heterogeneous, and the CAT-based QQ method is feasible to capture cerebral oxygen metabolic information.

Influence of post-label delay time on the performance of 3D pseudo-continuous arterial spin labeling magnetic resonance imaging in the characterization of parotid gland tumors.

To evaluate the influence of post-label delay times (PLDs) on the performance of 3D pseudo-continuous arterial spin labeling (pCASL) magnetic resonance imaging for characterizing parotid gland tumors and to explore the optimal PLDs for the differential diagnosis. Fifty-eight consecutive patients with parotid gland tumors were enrolled, including 33 patients with pleomorphic adenomas (PAs), 16 patients with Warthin's tumors (WTs), and 9 patients with malignant tumors (MTs). 3D pCASL was scanned for each patient five times, with PLDs of 1025 ms, 1525 ms, 2025 ms, 2525 ms, and 3025 ms. Tumor blood flow (TBF) was calculated, and compared among different PLDs and tumor groups. Performance of TBF at different PLDs was evaluated using receiver operating characteristic analysis. With an increasing PLD, TBF tended to gradually increase in PAs (p < 0.001), while TBF tended to slightly increase and then gradually decrease in WTs (p = 0.001), and PAs showed significantly lower TBF than WTs at all 5 PLDs (p < 0.05). PAs showed significantly lower TBF than MTs at 4 PLDs (p < 0.05), except at 3025 ms (p = 0.062). WTs showed higher TBF than MTs at all 5 PLDs; however, differences did not reach significance (p > 0.05). Setting a TBF of 64.350 mL/100g/min at a PLD of 1525 ms, or a TBF of 23.700 mL/100g/min at a PLD of 1025 ms as the cutoff values, optimal performance could be obtained for differentiating PAs from WTs (AUC = 0.905) or from MTs (AUC = 0.872). Short PLDs (1025 ms or 1525 ms) are suggested to be used in 3D pCASL for characterizing parotid gland tumors in clinical practice. • With 5 different PLDs, 3D pCASL can reflect the variation of blood flow in parotid gland tumors. • 3D pCASL is useful for characterizing PAs from WTs or MTs. • Short PLDs (1025 ms or 1525 ms) are suggested to be used in 3D pCASL for characterizing parotid gland tumors in clinical practice.

Non-invasive Diagnosis and Prognosis Values of 3D Pseudocontinuous Arterial Spin Labeling and Optical Coherence Tomography Angiography in Proliferative Diabetic Retinopathy.

Background: 3D Pseudocontinuous Arterial Spin Labeling (3D-PCASL) MRI and optical coherence tomography angiography (OCTA) have been applied to detect ocular blood flow (BF). We aim to characterize the ocular BF in diabetic retinopathy (DR) using 3D-PCASL and OCTA, to discuss the relationship between ocular and cerebral BF, and to evaluate their potential utility to assess the severity of DR.Methods: A total of 66 participants (132 eyes) were included. Seventy-two eyes were classified in the proliferative diabetic retinopathy (PDR) group, and 60 were in the non-proliferative diabetic retinopathy NPDR group. Ocular and cerebral BF values were detected by 3D-PCASL using a 3.0T MRI scanner with two post-labeling delays (PLDs). Vessel density (VD)/perfusion density (PD) of the macular or peripapillary area were detected by OCTA. Parameters and clinical characteristics were compared between the PDR and NPDR eyes utilizing two-sample t-tests and chi-square tests. Spearman's rank correlation analysis, logistic regression analysis, and receiver operating characteristic curves (ROC) analyses were performed to evaluate the factors' role in DR severity.Results: The perfusions of the retinal/choroidal plexus (RCP), optic nerve head (ONH)/optic nerve (ON), and VD/PD of macular/peripapillary area in the PDR group were significantly lower compared to the NPDR group (p < 0.05). They were protective factors for PDR [ORs = 0.842 for RCP (1.5 s PLD), 0.910 for ONH (1.5 s PLD), 0.905 for ON (both 1.5 and 2.5 s PLD), 0.707 for macular VD, 0.652 for peripapillary VD, p < 0.05, respectively]. Ocular BF had a positive correlation with BF of the occipital lobe (OL) and temporal lobe (TL) in the cerebrum. The BF of RCP (lower than 7.825 mL/min/100 g at 1.5 s PLD) indicated PDR [areas under the curve (AUCs) = 0.682, 95% CI: 0.588–0.777, sensitivity: 70.7% specificity: 63.9%]. The AUC of RCP (PLD = 1.5 s) BF combined with peripapillary VD was 0.841 (95% CI: 0.588–0.777, sensitivity: 75.9% specificity: 82.9%).Conclusions: 3D-pcASL and OCTA may be effective non-invasive methods to measure ocular blood flow in DR patients and assess the severity of DR.

211-OR: Differential Cerebral Blood Flow in Controlled and Uncontrolled Patients with Type 2 Diabetes Mellitus

Introduction: Patients with type 2 diabetes mellitus (T2DM) show variable brain tissue changes and mood and cognitive symptoms, which may result from altered cerebral blood flow (CBF). However, the regional CBF status in controlled and uncontrolled T2DM patients remains unclear, which can be examined with arterial spin labeling (ASL) imaging. Our aim was to examine regional CBF between controlled and uncontrolled T2DM patients using ASL imaging procedures. Methods: We collected hemoglobin A1c (A1C) data and 3D pseudo-continuous ASL data from 32 T2DM patients (16 controlled [A1C &amp;lt; 7%], age, 56.5±6.5 years; BMI, 29.6±6.2 kg/m2; 8 female; 16 uncontrolled [A1C ≥ 7%], age, 57.6±7.5 years; BMI, 30.0±5.1 kg/m2; 11 female) using a 3.0-Tesla MRI. A1C was measured by point-of-care testing. Whole-brain CBF maps were calculated, normalized to a common space, smoothed, and compared between groups (controlled T2DM patients vs. uncontrolled T2DM patients) using analysis of covariance (SPM12; covariates, age and sex; p&amp;lt;0.05). Results: No significant differences in age or sex appeared between groups. Multiple brain areas showed decreased CBF values in the cingulate, caudate, putamen, insula, hippocampus, amygdala, thalamus, hypothalamus, midbrain, cerebellum, prefrontal and frontal, and temporal cortices in uncontrolled T2DM patients over controlled T2DM patients. However, few brain sites in controlled T2DM patients, including the cerebellum, pons, medulla, parahippocampal gyrus, and temporal cortices showed reduced CBF over uncontrolled T2DM patients. Conclusion: Uncontrolled T2DM patients show significant reduction in CBF compared to controlled T2DM in areas that are involved in mood and cognition regulation. The findings suggest that uncontrolled levels may contribute to reduce regional CBF leading to site-specific tissue changes resulting to mood and cognition deficits in the condition. Disclosure S. E. Choi: None. B. Roy: None. M. Freeby: Research Support; Self; Abbott Diabetes, Novo Nordisk Inc. R. Kumar: None. Funding National Institutes of Health (1R01NR017190-03, 3R01NR017190-03S1)

Can 3D pseudo-continuous arterial spin labeling perfusion imaging be applied to predict early response to chemoradiotherapy in patients with advanced nasopharyngeal carcinoma?

Background and purposeChemoradiotherapy (CRT) has been widely applied in patients with advanced nasopharyngeal carcinoma (ANPC). However, limited imaging modality exists on the evaluation of early response to CRT. The purpose of this study was therefore to investigate whether 3D pseudo-continuous arterial spin labeling (3D pCASL) perfusion imaging could predict early response to CRT in ANPC patients. Materials and methodsSeventy ANPC patients who received CRT underwent pre-treatment MRI including 3D pCASL perfusion measurements, and were categorized into response group (RG) and no-response group (NRG) according to RECIST 1.1. Pre-treatment 3D pCASL derived cerebral blood flow (CBF) values in tumors were compared between RG and NRG patients. Receiver-operating characteristic (ROC) analysis was performed to determine the optimal diagnostic cutoff value for CBF in predicting tumor response to CRT. Clinicopathological variables were also analyzed by using univariate and binary logistic regression. The corresponding obtained variables with statistical significance were further applied to create a nomogram in which the bootstrap resampling method was used for calibration. ResultsForty-eight patients in RG had significantly higher pre-treatment CBF values in tumors compared with 22 patients in NRG (P < 0.001). CBF showed the high area under the ROC curve (AUC = 0.843) in distinguishing RG from NRG patients. The corresponding cutoff value for CBF was 103.68 ml/100 g/min, with respective accuracy, sensitivity and specificity of 82.86%, 87.50% and 72.73%. The nomogram was generated by binary logistic regression results, incorporating three variables: CBF value, clinical stage and pathological type. The AUC, accuracy, sensitivity and specificity of the nomogram was respectively 0.893, 84.28%, 81.25% and 90.91% in predicting tumor response to CRT. Moreover, as shown in the calibration curve, a strong agreement was observed between nomogram prediction probability and actual clinical findings (P = 0.309). Conclusions3D pCASL derived CBF in tumor could act as a noninvasive effective biomarker to predict tumor response to CRT in ANPC patients before clinical treatment. Furthermore, the nomogram combining CBF and clinicopathological variables could serve as a novel clinical analysis tool for treatment response prediction.