Blood Oxygen Level-Dependent MR Imaging of Lower Extremities in Peripheral Artery Disease and Its Correlation With Walking Performance.

BACKGROUND: A noninvasive and reliable approach to quantitatively measure muscle perfusion of lower extremity is needed to aid the diagnosis and treatment of peripheral artery disease (PAD). PURPOSE: To verify the reproductivity of using blood oxygen level-dependent (BOLD) imaging to evaluate perfusion in lower extremities, and explore its correlation with walking performance in patients with PAD. STUDY TYPE: Prospective observational study. SUBJECTS: Seventeen patients with lower extremity PAD (mean age: 67 ± 6 years, 15 males) and eight older adults (controls). FIELD STRENGTH/SEQUENCE: Dynamic multi-echo gradient echo T2* weighted imaging at 3T. ASSESSMENT: Perfusion was analyzed in regions of interest according to muscle groups. Perfusion parameters were measured, such as minimum ischemia value (MIV), time to peak (TTP), and gradient during reactive hyperemia (Grad) by two independent users. Walking performance experiments including short physical performance battery (SPPB) and 6-minute walk were tested in patients. STATISTICAL TESTS: BOLD parameters were compared using Mann-Whitney U test and Kruskal-Wallis test. Relations between parameters and walking performance were assessed by Mann-Whitney U test and Spearman's correlation coefficient. RESULTS: Good to perfect agreement was demonstrated for all perfusion parameters of interuser reproducibility, and the interscan reproducibility of MIV, TTP, and Grad was good. The TTP of the patients was longer than that of the controls (87.85 ± 38.85 s vs. 36.54 ± 7.27 s), while the Grad of patients was smaller (0.16 ± 0.12 msec/s vs. 0.24 ± 0.11 msec/s). Among PAD patients, the MIV was significantly lower in the low SPPB subgroup (score 6-8) than in the high SPPB group (score 9-12), and the TTP was negatively correlated with 6-minute walk distance (ρ = -0.549). DATA CONCLUSION: BOLD imaging method had overall good reproducibility for the perfusion assessment of calf muscles. The perfusion parameters were different between PAD patients and controls, and were correlated with lower extremity function. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Multidelay MR Arterial Spin Labeling Perfusion Map for the Prediction of Cerebral Hyperperfusion After Carotid Endarterectomy.

BACKGROUND: Multidelay arterial spin labeling (ASL) generates time-resolved perfusion maps, which may provide sufficient and accurate hemodynamic information in carotid stenosis. PURPOSE: To use imaging markers derived from multidelay ASL magnetic resonance imaging (MRI) and to determine the optimal strategy for predicting cerebral hyperperfusion after carotid endarterectomy (CEA). STUDY TYPE: Prospective observational cohort. SUBJECTS: A total of 79 patients who underwent CEA for carotid stenosis. FIELD STRENGTH/SEQUENCE: A 3.0 T/pseudo-continuous ASL with three postlabeling delays of 1.0, 1.57, and 2.46 seconds using fast-spin echo readout. ASSESSMENT: Cerebral perfusion pressure, antegrade, and collateral flow were scored on a four-grade ordinal scale based on preoperative multidelay ASL perfusion maps. Simultaneously, quantitative hemodynamic parameters including cerebral blood flow (CBF), arterial transit time (ATT), relative CBF (rCBF) and relative ATT (rATT; ipsilateral/contralateral values) were calculated. On the CBF ratio map obtained through dividing postoperative by preoperative CBF map, regions of interest were placed covering ipsilateral middle cerebral artery territory. Three neuroradiologists conducted this procedure. Cerebral hyperperfusion was defined as a CBF ratio >2. STATISTICAL TESTS: Weighted κ values, independent sample t test, chi-square test, Mann-Whitney U-test, multivariable logistic regression analysis, receiver-operating characteristic curve analysis, and Delong test. Significance level was P < 0.05. RESULTS: Cerebral hyperperfusion was observed in 15 (19%) patients. Higher blood pressure (odd ratio [OR] = 1.08) and carotid near-occlusion (NO; OR = 7.31) were clinical risk factors for postoperative hyperperfusion. Poor ASL perfusion score (OR = 37.33), decreased CBF (OR = 0.74), prolonged ATT (OR = 1.02), lower rCBF (OR = 0.91), and higher rATT (OR = 1.12) were independent imaging predictors of hyperperfusion. ASL perfusion score exhibited the highest specificity (95.3%), while CBF exhibited the highest sensitivity (93.3%) for the prediction of hyperperfusion. When combined with ASL perfusion score, CBF and ATT, the predictive ability was significantly higher than using blood pressure and NO alone (AUC: 0.98 vs. 0.78). DATA CONCLUSIONS: Multidelay ASL can accurately predict cerebral hyperperfusion after CEA with high sensitivity and specificity. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 5.

Study protocol of Branch Atheromatous Disease-related stroke (BAD-study): a multicenter prospective cohort study.

BACKGROUND: As a meaningful subtype of ischemic stroke in Asians, Branch atheromatous disease (BAD)-related stroke is associated with high early neurological deterioration (END) and disability, but is understudied and without recommended therapy. The mechanism of END still remains unclear. Branch atheromatous disease-related stroke study (BAD-study) therefore aims to investigate demographic, clinical and radiological features, and prognosis of BAD-related stroke in Chinese patients. METHODS/DESIGN: BAD-study is a nationwide, multicenter, consecutive, prospective, observational cohort study enrolling patients aged 18-80 years with BAD-related stroke within 72 h after symptom onset. Initial clinical data, laboratory tests, and imaging data are collected via structured case report form, and follow-ups will be performed at 7 days, 30 days, 90 days, 6 months and 12 months after enrollment. The primary outcome is the score on modified Rankin Scale at 90-day follow-up with single-blinded assessment. Secondary outcomes include END within 7 days, and National institute of health stroke scale score, Barthel index, cerebrovascular events, major bleeding complications, and all-cause mortality during 90-day follow-up. Characteristics of penetrating and parent artery will be assessed by high-resolution magnetic resonance imaging combined with other imaging techniques. DISCUSSION: BAD-study can provide demographic, clinical, radiological, and prognostic characteristics of BAD-related stroke, and thereby potentially figure out the vascular mechanism of early neurological deterioration and optimize therapy strategy with the aid of advanced imaging technique. Baseline data and evidence will also be generated for randomized controlled trials on BAD-related stroke in the future.

Arterial transit artifacts on arterial spin labeling MRI can predict cerebral hyperperfusion after carotid endarterectomy: an initial study.

OBJECTIVES: To investigate whether preoperative arterial spin labeling (ASL) MRI can predict cerebral hyperperfusion after carotid endarterectomy (CEA) in patients with carotid stenosis. METHODS: Consecutive patients with carotid stenosis who underwent CEA between May 2015 and July 2021 were included. For each patient, a cerebral blood flow ratio (rCBF) map was obtained by dividing postoperative CBF with preoperative CBF images from two pseudo-continuous ASL scans. Hyperperfusion regions with rCBF > 2 were extracted and weighted with rCBF to calculate the hyperperfusion index. According to the distribution of the hyperperfusion index, patients were divided into hyperperfusion and non-hyperperfusion groups. Preoperative ASL images were scored based on the presence of arterial transit artifacts (ATAs) in 10 regions of interest corresponding to the Alberta Stroke Programme Early Computed Tomography Score methodology. The degree of stenosis and primary and secondary collaterals were evaluated to correlate with the ASL score. Logistic regression and receiver operating characteristic curve analyses were performed to assess the predictive ability of the ASL score for cerebral hyperperfusion. RESULTS: Of 86 patients included, cerebral hyperperfusion was present in 17 (19.8%) patients. Carotid near occlusion, opening of posterior communicating arteries with incomplete anterior semicircle, and leptomeningeal collaterals were associated with lower ASL scores (p < 0.05). The preoperative ASL score was an independent predictor of cerebral hyperperfusion (OR = 0.48 [95% CI [0.33-0.71]], p < 0.001) with the optimal cutoff value of 25 points (AUC = 0.98, 94.1% sensitivity, 88.4% specificity). CONCLUSIONS: Based on the presence of ATAs, ASL can non-invasively predict cerebral hyperperfusion after CEA in patients with carotid stenosis. KEY POINTS: • Carotid near occlusion, opening of posterior communicating arteries with incomplete anterior semicircle, and leptomeningeal collaterals were associated with lower ASL scores. • The ASL score performed better than the degree of stenosis, type of CoW, and leptomeningeal collaterals, as well as the combination of the three factors for the prediction of cerebral hyperperfusion. • For patients with carotid stenosis, preoperative ASL can non-invasively identify patients at high risk of cerebral hyperperfusion after carotid endarterectomy without complex post-processing steps.

Numerical simulation of foundation pit dewatering using horizontal seepage reducing body.

Groundwater level has to be lowered during deep excavation. A vertical curtain is usually adopted to control the drawdown inside and outside a foundation pit in a built-up area. However, the cost and working difficulty increases substantially with the rise in depth of vertical curtains. In the manuscript, a man-made horizontal seepage reducing body (HSRB) was introduced to shorten the vertical curtain depth and control drawdown. With the No. 4 shaft foundation pit of Guangyuan Project, Shanghai as background, HSRB was proposed in foundation pit dewatering. Microbially induced carbonate precipitation grouting technology was recommended to form an environment-friendly HSRB. Numerical method was used to simulate and understand the influence of position, thickness, and hydraulic conductivity of HSRB on groundwater level. The non-separated HSRB was better than the separate HSRB. Decreasing HSRB hydraulic conductivity was better than increasing HSRB depth. Four seepage modes were summarized considering vertical curtain penetration conditions into multi-aquifer, and the fifth seepage mode was formed for vertical curtain using man-made HSRB, which can be referred by similar engineering applications.

A pilot study of the association between leukoaraiosis and cerebral atherosclerosis using synthetic magnetic resonance imaging.

BACKGROUND: Leukoaraiosis is a type of lesion characterized by tissue rarefaction or myelin pallor resulting from axons loss and gliosis. Synthetic magnetic resonance imaging (MRI) could yield quantitative T1, T2, proton density (PD) values of leukoaraiosis in addition to information on the volume of the lesion. PURPOSE: To investigate the feasibility of quantifying leukoaraiosis using synthetic MRI and to explore the association between leukoaraiosis and cerebral small vascular diseases and cerebral atherosclerosis. MATERIAL AND METHODS: Patients with acute ischemic stroke were enrolled in this study. All participants underwent a conventional T2-weighted image, brain volume, CUBE fluid attenuated inversion recovery, and synthetic MRI acquisition using a 3.0-T MR system. A time-of-flight magnetic resonance angiography was also obtained. We evaluated the T1, T2, PD values and leukoaraiosis volume. RESULTS: Analysis of the leukoaraiosis volume ratios demonstrated a positive association with T2 values, a negative association with T1 values, and no association with PD values. Leukoaraiosis volume ratios were independently correlated with age (P < 0.001), lacunes (P = 0.022), and cerebral microbleeds (P = 0.010). A statistical association was found between both age (P < 0.001) and lacunes (P = 0.047) and leukoaraiosis T2 values. CONCLUSION: Synthetic MRI may enhance the evaluation of leukoaraiosis, in addition to providing information on its volume. Leukoaraiosis may represent a type of cerebral small vascular disease rather than cerebral atherosclerosis and may share the same pathological mechanism as lacunes and cerebral microbleeds.

Assessment of blood supply of the external carotid artery in moyamoya disease using super-selective pseudo-continuous arterial spin labeling technique.

OBJECTIVES: To evaluate the diagnostic accuracy of super-selective pseudo-continuous arterial spin labeling (ss-pCASL) at depicting external carotid artery (ECA) perfusion territory in moyamoya disease (MMD). METHODS: In total, 103 patients with MMD who underwent both ss-pCASL and digital subtraction angiography (DSA, the reference standard) were included. There were 3, 184, and 19 normal, preoperative, and postoperative MMD hemispheres, respectively. The ss-pCASL results were interpreted by two different visual inspection criteria: presence or absence and definite or indefinite ECA perfusion territory. The performance of ss-pCASL at depiction of ECA perfusion territory was compared to that of DSA. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. The κ statistic was used to assess intermodality and inter-reader agreement. RESULTS: When interpreted as presence or absence, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ss-pCASL for depicting ECA perfusion territory were 78.3 %, 79.6 %, 92.5 %, 53.4 %, and 78.6 %, respectively, and the intermodality and inter-reader agreement were κ = 0.49 (CI: 0.43 - 0.55, p < 0.01) and 0.71 (CI: 0.66 - 0.76, p < 0.01), respectively. When interpreted as definite or indefinite, the respective values were 61.1%, 100%, 100%, 44.5%, 70.4%, κ = 0.42 (CI: 0.37 - 0.47, p < 0.01), and 0.90 (CI: 0.87 - 0.93, p < 0.01). CONCLUSION: ss-pCASL has substantial sensitivity and specificity compared with DSA for depicting the presence versus absence of ECA perfusion territory in MMD. As a noninvasive method in which no ion radiation or contrast medium is needed, ss-pCASL may potentially reduce the need for repeated DSA examination. KEY POINTS: • Super-selective pseudo-continuous arterial spin labeling (ss-pCASL) is a noninvasive vessel-selective MR technique to demonstrate perfusion territory of a single cerebral artery. • Compared with digital subtraction angiography, ss-pCASL has substantial sensitivity and specificity for depicting the perfusion territory of the external carotid artery in brain parenchyma in moyamoya disease. • ss-pCASL may potentially reduce the need for repeated DSA examination.

Quantitative T2 mapping-based tendon healing is related to the clinical outcomes during the first year after arthroscopic rotator cuff repair.

PURPOSE: The objective of this study was to determine the correlation between quantitative T2 mapping-based tendon healing and clinical outcomes during the first year after arthroscopic rotator cuff repair. METHODS: Twenty-two patients with rotator cuff tear were prospectively recruited. Serial clinical and MRI follow-up assessments were carried out at 1 month, 6 months and 12 months after surgery. Twenty healthy volunteers were involved and were examined with clinical and MRI assessments. Clinical assessments included Constant Score (CS), the American Shoulder and Elbow Surgeons (ASES), the modified University of California, Los Angles (UCLA) scores and Visual Analog Scale (VAS). The region of interest of tendon healing was defined directly over the medial suture anchor on T2 mapping. Spearman correlation coefficient was used to analyze the correlations between MRI measurements and clinical outcomes. RESULTS: All clinical scores indicated significant improvements over the postoperative observation period compared with the initial preoperative values (all P < 0.001). At 12 months, all of the patients returned to their daily life activities. The T2 values of the healing site significantly decreased over time (P < 0.001) and were comparable to those of healthy tendons at 12 months (n.s.). Additionally, the T2 values were negatively correlated with CS (r = - 0.5, P < 0.001), ASES (r = - 0.5, P < 0.001), and UCLA (r = - 0.5, P < 0.001); and positively correlated with VAS score (r = 0.4, P < 0.001). No significant correlations were found between Sugaya classification and clinical scores (all n.s.). CONCLUSIONS: With regard to tendon healing during the first follow-up year, the T2 values of the healing site decreased with the improvement of clinical outcomes over time. LEVEL OF EVIDENCE: II.

Quantitative Magnetic Resonance Imaging UTE-T2* Mapping of Tendon Healing After Arthroscopic Rotator Cuff Repair: A Longitudinal Study.

BACKGROUND: Quantitative ultrashort echo time-T2* (UTE-T2*) mapping shows promise for the detection of potential tendon biochemical conditions, while validation against established clinical studies in the shoulder is needed. PURPOSE: To evaluate and characterize the healing process of the repaired rotator cuff based on longitudinal changes in UTE-T2* values, clinical outcomes, and repair status in patients after arthroscopic rotator cuff repair (ARCR). STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Patients with ARCR (n = 25) underwent quantitative MRI and clinical examinations at serial follow-up time points: 3, 6, 12, and 24 months postoperatively. Age-matched healthy controls (n = 15) were evaluated at 3 and 12 months after enrollment. Clinical scores included the Constant, American Shoulder and Elbow Surgeons, and Fudan University Shoulder score, and visual analog scale for pain. The MRI examination included UTE-T2*mapping. UTE-T2* maps were generated for T2* values at the healing site. Sugaya classification was adopted to evaluate the repair status. Longitudinal analyses of clinical outcomes, UTE-T2* changes, and Sugaya classification were conducted. RESULTS: The overall retear rate was 8% (2/25, all Sugaya type IV). All patients (including the ones with retear) achieved satisfactory outcomes at 12 months that lasted to 24 months on the basis of clinical scores. The mean UTE-T2* values at the healing site showed an increase from 3 to 6 months (P = .03) and then decreased to a level similar to that observed in age-matched healthy tendons at 12 months (P = .1). No significant differences were found between UTE-T2* values at 12 and 24 months (P = .6). UTE-T2* values at the healing site significantly varied with the repair status according to Sugaya classification (P < .05). Moreover, significant correlations were noted between clinical scores and UTE-T2* values at 6 months (r = -0.6 to -0.3; all P < .05) and 12 months (r = -0.6 to -0.2; all P < .05). CONCLUSION: This study indicated a healing-related relationship between clinical outcomes and quantitative UTE-T2* values, which highlights the potential of using UTE-T2* mapping to track the tendon-healing process noninvasively. Moreover, the repaired tendon was comparable to age-matched healthy controls at 12-month follow-up based on UTE-T2* values.

Test-retest reliability and reproducibility of long-label pseudo-continuous arterial spin labeling.

PURPOSE: Arterial spin labeling MRI can quantify the cerebral blood flow (CBF) without exogenous tracer. However, the variation of arterial transit time across different brain regions introduces bias for measuring local CBF, especially for those subjects with long arterial transit time (ATT). Long post-labeling delay (PLD) or multi-PLD methods could mitigate the problem of heterogenous ATT at the expense of the signal-to-noise ratio (SNR). Long-label ASL might address the low SNR problem by increasing the amount of labeled arterial blood. Thus, we hypothesized that with the same relatively long PLD, long-label pCASL may be more robust and reproducible than standard-label pCASL in population with potentially prolonged ATT. The purpose of the study was to investigate the reliability and reproducibility of long-label pCASL in the whole brain and vascular regions of interest in an elderly population, compared with standard-label pCASL. METHOD: Twenty adult volunteers (14 males, 6 females; age, 56.6 ± 17.2 years) were scanned twice on one 3.0 T scanner by standard-label pCASL (label duration (LD) = 1500 ms, PLD = 2000 ms) and long-label pCASL (LD = 3500 ms, PLD = 2000 ms). The intraclass correlation coefficient (ICC), within-subject coefficient of variation (wsCV), random noise and signal coefficient of variation(CoV) were used to assess global and regional reliability and reproducibility. Measurement agreement and difference were compared in different brain regions using correlation coefficient plots and Bland-Altman plots respectively. RESULTS: CBF value measured by long-label pCASL was overall higher than standard-label pCASL in all ROIs. Long-label pCASL had higher ICC than standard-label pCASL in most ROIs, and lower wsCV, random noise and CoV in all ROIs. Regardless of ASL method used, anterior circulation flow territories (ICC, 0.93-0.97; wsCV, 0.03-0.06) had higher CBF reliability and reproducibility than posterior circulation flow territories (ICC, 0.89; wsCV, 0.06-0.08). In all ROIs, the correlation analysis showed higher test-retest agreement (rlong-label > rstandard-label) and the Bland-Altman plots demonstrated lower measurement difference in long-label pCASL. CONCLUSION: The study demonstrated good reliability and reproducibility of long-label pCASL in anterior brain regions in the elderly population. To further improve CBF quantification in a long-ATT population while proper PLD is already used, increasing the label duration may help.

Iron Sucrose as MRI Contrast Agent in Ischemic Stroke Model.

BACKGROUND: Despite the growing concern about the safety of gadolinium-based contrast agents (GBCAs), they are still the most commonly used. Ferumoxytol, as an off-label alternative MRI contrast agent, cannot be administered by a rapid bolus for dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI). PURPOSE: To assess the feasibility of iron sucrose (IS) as a contrast agent for MR angiography (MRA) and DSC-PWI. STUDY TYPE: Prospective animal model. ANIMAL MODEL: Thirty-six normal rats (16 for MRA, 20 for biocompability tests) and 36 occlusion of the middle cerebral artery (MCAO) model rats. FIELD STRENGTH/SEQUENCE: 3.0T; head and neck angiography, using a fast spoiled gradient-recalled-echo (FSPGR) sequence and DSC-MRI using echo planar imaging(EPI) sequence. ASSESSMENT: MRA was performed on normal rats to examine the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of different doses of IS. DSC-PWI was performed on MCAO rats at 0, 24, 48, and 72 hours postreperfusion to investigate the lesion detectability of IS. Arterial spin labeling (ASL) and DSC-PWI enhanced by GBCAs were conducted on MCAO rats as controls. STATISTICAL TESTS: Kruskal-Wallis test was used to compare qualitative assessment. One-way analysis of variance (ANOVA) was used to compare the parametric data. Pearson's r values were evaluated between relative cerebral blood flow(rCBF)-ASL, rCBF-DSCIS , and rCBF obtained from DSC-PWI enhanced by GBCA. RESULTS: The mean SNR and CNR of the common carotid artery at doses of 10 mg Fe/kg of IS were comparable with the standard dose of GBCAs (SNR: 68.04 ± 12.55 vs. 67.72 ± 14.66; CNR: 23.78 ± 7.21vs. 21.63 ± 6.83). In MCAO rat models, rCBF and relative cerebral blood volume (rCBV) of ipsilateral striatum declined (0.72 ± 0.14, 0.86 ± 0.11) with prolonged relative mean transit time (rMTT) and relative time-to-peak (rTTP) (1.27 ± 0.24, 1.07 ± 0.03) following occlusion. Hyperperfusion was observed in all rats at 48 and 72 hours postreperfusion, in 4/6 rats at 24 hours postreperfusion for IS-mediated DSC-PWI. DATA CONCLUSION: IS may be an effective contrast agent for both MRA and DSC-PWI in ischemic stroke models. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1 J. Magn. Reson. Imaging 2020;52:836-849.

Quantitative synthetic MRI for evaluation of the lumbar intervertebral disk degeneration in patients with chronic low back pain.

PURPOSE: To verify the feasibility of synthetic MRI in quantitative evaluation of lumbar intervertebral disk (IVD) degeneration, as compared to the conventional CarrPurcell-Meiboom-Gill (CPMG) T2 mapping approach. METHODS: Twenty-four patients with chronic low back pain participated in this study. Patients underwent routine lumbar MRI, CPMG T2 mapping, and synthetic MRI (MAGiC) acquisition. The degree of IVD degeneration was derived from T2-weighted images according to the Pfirrmann classification. The correlation between two T2 measurements was assessed by Pearson correlation and Bland-Altman analysis. Statistical differences of quantitative values obtained from MAGiC data across different degeneration grades were quantified by one-way ANOVA. ROC curves were used to test the sensitivity and specificity of CPMG and MAGiC T2 measurements for assessing Pfirrmann grading. RESULTS: T2 values obtained from CPMG and MAGiC data exhibited strong positive correlation (r = 0.962, p < 0.01). Significant negative correlations were found between quantitative values (p < 0.05) and the Pfirrmann grading. Quantitative values show significant difference across Pfirrmann grading groups (one-way ANOVA, p < 0.001). Additionally, post-hoc tests show significant differences of T1 and T2 between adjacent groups among grades I-IV (p < 0.05), while the significant differences of PD were only observed between adjacent groups among grades II-IV (p < 0.05). There is no significant difference between AUCs of T2 values obtained from CPMG and MAGiC data in differentiating grade I/ II, grade II/ III and grade III/IV. CONCLUSIONS: The synthetic MRI may be used to provide quantitative biomarkers for assessing the level of lumbar intervertebral disc degeneration.

A perfusion territory shift attributable solely to the secondary collaterals in moyamoya patients: a potential risk factor for preoperative hemorrhagic stroke revealed by t-ASL and 3D-TOF-MRA.

OBJECTIVE: The authors conducted a study to noninvasively and nonradioactively reveal moyamoya disease (MMD) intracerebral perfusion and perfusion territory supplied by the unilateral internal carotid artery (ICA) and external carotid artery (ECA) and bilateral vertebral arteries (VAs) before surgery and to further identify risk factors for preoperative hemorrhage in adult MMD. METHODS: Forty-three consecutive adult patients with bilateral MMD underwent unenhanced T1-weighted MRI, territorial arterial spin labeling (t-ASL), and unenhanced 3D time-of-flight MRA (3D-TOF-MRA). Clinical factors, including age, sex, hypertension, diabetes mellitus, hyperlipidemia, current smoking status, and history of taking aspirin, were gathered and stratified. Univariate logistic regression analyses were used to examine the relationship between various risk factors and the occurrence of preoperative hemorrhage. Stepwise multivariate logistic regression analyses were used to determine independent risk factors of preoperative hemorrhage in MMD. RESULTS: Among the 86 MMD hemispheres, t-ASL revealed 137 perfusion territory shifts in 79 hemispheres. Five distinct categories of perfusion territory shifts were observed on t-ASL maps. The subtypes of perfusion territory shift on t-ASL maps were further subdivided into 2 different categories, group A and group B, in combination with findings on 3D-TOF-MRA. A perfusion territory shift attributable solely to the secondary collaterals was a potential independent risk factor for preoperative hemorrhage (p = 0.026; 95% CI 1.201-18.615; OR 4.729). After eliminating the influence of the secondary collaterals, the primary collaterals had no significant effect on the risk of preoperative hemorrhage (p = 0.182). CONCLUSIONS: t-ASL could reveal comprehensive MMD cerebral blood perfusion and the vivid perfusion territory shifts fed by the unilateral ICA and ECA and bilateral VAs in a noninvasive, straightforward, nonradioactive, and nonenhanced manner. 3D-TOF-MRA could subdivide t-ASL perfusion territory shifts according to their shunt arteries. A perfusion territory shift attributable to the secondary collaterals is a potential independent risk factor for preoperative hemorrhage in MMD patients. A perfusion territory shift fed by the primary collaterals may not have a strong effect on preoperative hemorrhage in MMD patients. These findings make the combined modalities of t-ASL and 3D-TOF-MRA a feasible tool for MMD disease assessment, management, and surgical strategy planning.

Engineering human ventricular heart tissue based on macroporous iron oxide scaffolds.

Myocardial infarction (MI) is a primary cardiovascular disease threatening human health and quality of life worldwide. The development of engineered heart tissues (EHTs) as a transplantable artificial myocardium provides a promising therapy for MI. Since most MIs occur at the ventricle, engineering ventricular-specific myocardium is therefore more desirable for future applications. Here, by combining a new macroporous 3D iron oxide scaffold (IOS) with a fixed ratio of human pluripotent stem cell (hPSC)-derived ventricular-specific cardiomyocytes and human umbilical cord-derived mesenchymal stem cells, we constructed a new type of engineered human ventricular-specific heart tissue (EhVHT). The EhVHT promoted expression of cardiac-specific genes, ion exchange, and exhibited a better Ca2+ handling behaviors and normal electrophysiological activity in vitro. Furthermore, when patched on the infarcted area, the EhVHT effectively promoted repair of heart tissues in vivo and facilitated the restoration of damaged heart function of rats with acute MI. Our results show that it is feasible to generate functional human ventricular heart tissue based on hPSC-derived ventricular myocytes for the treatment of ventricular-specific myocardium damage. STATEMENT OF SIGNIFICANCE: We successfully generated highly purified homogenous human ventricular myocytes and developed a method to generate human ventricular-specific heart tissue (EhVHT) based on three-dimensional iron oxide scaffolds. The EhVHT promoted expression of cardiac-specific genes, ion exchange, and exhibited a better Ca2+ handling behaviors and normal electrophysiological activity in vitro. Patching the EhVHT on the infarct area significantly improved cardiac function in rat acute MI models. This EhVHT has a great potential to meet the specific requirements for ventricular damages in most MI cases and for screening drugs specifically targeting ventricular myocardium.

Reversible Dilation of Cerebral Macrovascular Changes in MELAS Episodes.

PURPOSE: To investigate the cerebral macrovascular changes as well as the relationship of large vessels and cerebral blood flow (CBF) in mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) using magnetic resonance angiography (MRA) and arterial spin labeling (ASL) perfusion MR imaging (MRI). METHODS: A total of 20 patients diagnosed with MELAS (12 males, 8 females; mean age, 23.3 years) underwent conventional MRI, time-of-flight (TOF) MRA and three dimensional ASL. Follow-up scans were performed in 10 patients. The changes of cerebral arteries and branches on MRA images from both acute and recovery patients were independently evaluated by two radiologists. Lesion distribution and CBF were observed on the integrated maps of MRA and ASL. RESULTS: In 14 patients with clinical onsets, increased CBF was observed in all stroke-like lesions. Dilations of a single artery (four middle cerebral arteries, two posterior cerebral arteries) were found in six patients. Dilations of multiple arteries (two anterior cerebral arteries, seven middle cerebral arteries, six posterior cerebral arteries) were found in seven patients. Normal angiography was shown in one acute patient. Cortical terminal branches feeding the lesion areas were more obviously dilated than the main trunks. The dilated vessels returned to normal on follow-up scans concurrently with decreased CBF in nine patients who were resuscitated from episode attacks. Vasodilation was even seen in one preclinical patient who suffered a recurrent episode 50 days later. CONCLUSION: Reversible dilation of cerebral macrovascular changes could be a new feature of MELAS and a presumed reason for fluctuant CBF. It would shed new light on the mitochondrial angiopathy.

ASL perfusion features and type of circle of Willis as imaging markers for cerebral hyperperfusion after carotid revascularization: a preliminary study.

OBJECTIVES: Cerebral hyperperfusion (CH) could be a disastrous outcome causing complication after carotid revascularization if not managed properly and timely. The aim of this study was to investigate the association between preoperative arterial spin labelling (ASL) perfusion features and circle of Willis (CoW) pattern with CH. METHODS: Forty-eight consecutive carotid stenosis patients who underwent carotid endarterectomy (CEA) or carotid artery stenting (CAS) were enrolled. All patients had single post-labelling delay (PLD) ASL, territory-ASL, and 3-dimensional time-of-flight MR angiography (3D TOF MRA) within 2 weeks before surgery and within 3 days after surgery. Spatial coefficient of variation (CoV) of cerebral blood flow (CBF), whole brain, and territory perfusion volume ratio were calculated from ASL and territory-ASL. Postoperative CoW was classified into two groups based on patency of the first segment of the anterior cerebral arteries (A1) and anterior communicating artery (AcomA). ASL perfusion features, type of CoW, and clinical characteristics were analyzed between CH group and non-CH group to identify CH risk factors. RESULTS: Higher CoV (p = 0.005) of CBF, lower whole brain perfusion volume ratio (p = 0.012), missing any of A1 or AcomA in CoW (p = 0.002 for postoperative MRA and p = 0.004 for preoperative MRA), and large artery stroke history (p = 0.028) were significantly associated with higher risk of CH. Two cases with cerebral hyperperfusion syndrome (CHS) were also discussed, and their perfusion and angiographic features were shown. CONCLUSIONS: Single-PLD ASL and MRA might be useful and non-invasive imaging tools to identify patients with higher risk of CH after carotid revascularization. KEY POINTS: • Cerebral hyperperfusion is a critical complication after carotid endarterectomy or carotid artery stenting. • ASL and MRA can be used to identify patients at higher risk of cerebral hyperperfusion • Pattern of circle of Willis, ASL perfusion features, and whole brain perfusion volume ratio are potential predicting markers for hyperperfusion after carotid revascularization.

Cerebral Perfusion Territory Changes After Direct Revascularization Surgery in Moyamoya Disease: A Territory Arterial Spin Labeling Study.

OBJECTIVE: To use territory arterial spin labeling (T-ASL) in the early postoperative period to evaluate the revascularization area (RA) obtained by superficial temporal artery-to-middle cerebral artery bypass and to evaluate subsequent perfusion territory changes of the major cerebral arteries. METHODS: Thirty patients with moyamoya disease treated via unilateral superficial temporal artery-to-middle cerebral artery bypass were included. T-ASL was performed preoperatively and within 1 week postoperatively. The RA was examined by labeling the superficial temporal artery-to-middle cerebral artery bypass postoperatively. Preoperative and postoperative perfusion territories of the bilateral internal carotid arteries, bilateral external carotid arteries, and basilar artery were also examined and compared. Postoperative computed tomography angiography was performed and compared with T-ASL results. RESULTS: In 14 of 30 patients (46.7%), T-ASL demonstrated the presence of an RA (RA-positive), whereas 16 patients (53.3%) had no RA (RA-negative). In the RA-positive group, mean volume of the RA was 80.32 ± 8.13 mL (range, 34.95-142.50 mL). Postoperative perfusion territory changes of the major cerebral arteries differed between the RA-positive group and the RA-negative group. The incidence of preoperative external carotid artery compensation was significantly higher in the RA-negative group than the RA-positive group (F = 0.011, df = 1, P < 0.05). There was good intermodality agreement between T-ASL and computed tomography angiography (κ = 0.780). CONCLUSIONS: T-ASL can demonstrate the RA obtained by direct revascularization and postoperative perfusion territory changes of the major cerebral arteries. T-ASL is a promising technique in postoperative evaluation of patients with moyamoya disease.

Brain T1ρ mapping for grading and IDH1 gene mutation detection of gliomas: a preliminary study.

INTRODUCTION: The longitudinal relaxation time in the rotating frame (T1ρ) has proved to be sensitive to metabolism and useful in application to neurodegenerative diseases. However, few literature exists on its utility in gliomas. Thus, this study was conducted to explore the performance of T1ρ mapping in tumor grading and characterization of isocitrate dehydrogenase 1 (IDH1) gene mutation status of gliomas. METHODS: Fifty-seven patients with gliomas underwent brain MRI and quantitative measurements of T1ρ and apparent diffusion coefficient (ADC) were recorded. Parameters were compared between high-grade gliomas (HGG) and low-grade gliomas (LGG) and between IDH1 mutant and wildtype groups. RESULTS: HGG showed significantly higher T1ρ values in both the solid and peritumoral edema areas compared with LGG (P < 0.001 and P = 0.005, respectively), whereas no significant differences in the two areas were found for ADC (both P > 0.05). Receiver operating characteristic (ROC) curve analysis showed that T1ρ value in the solid area achieved the highest area under the ROC curve (AUC, 0.841) in grading with a sensitivity of 80.6% and a specificity of 81.0%. In the grade II/III glioma group, multivariate logistic regression showed that both tumor frontal lobe location (odds ratio [OR] 526.608; P = 0.045) and T1ρ value of the peritumoral edema area (OR 0.863; P = 0.037) were significant predictors of IDH1 mutation. Using the combination, the diagnostic sensitivity and specificity for IDH1 mutated gliomas were 93.3% and 88.9%, respectively. CONCLUSIONS: Our study shows the feasibility of applying T1ρ mapping in assessing the histologic grade and IDH1 mutation status of gliomas.