AJNR. American journal of neuroradiology最新文献

Background and purpose: Normalized relative cerebral blood volume (nrCBV) and percentage of signal recovery (PSR) computed from dynamic susceptibility contrast (DSC) perfusion imaging are useful biomarkers for differential diagnosis and treatment response assessment in brain tumors. However, their measurements are dependent on DSC acquisition factors, and CBV-optimized protocols technically differ from PSR-optimized protocols. This study aimed to generate "synthetic" DSC data with adjustable synthetic acquisition parameters using dual-echo gradient-echo (GE) DSC datasets extracted from dynamic spin-and-gradient-echo echoplanar imaging (dynamic SAGE-EPI). Synthetic DSC was aimed at: 1) simultaneously create nrCBV and PSR maps using optimal sequence parameters, 2) compare DSC datasets with heterogeneous external cohorts, and 3) assess the impact of acquisition factors on DSC metrics.

Materials and methods: Thirty-eight patients with contrast-enhancing brain tumors were prospectively imaged with dynamic SAGE-EPI during a non-preloaded single-dose contrast injection and included in this cross-sectional study. Multiple synthetic DSC curves with desired pulse sequence parameters were generated using the Bloch equations applied to the dual-echo GE data extracted from dynamic SAGE-EPI datasets, with or without optional preload simulation.

Results: Dynamic SAGE-EPI allowed for simultaneous generation of CBV-optimized and PSR-optimized DSC datasets with a single contrast injection, while PSR computation from guideline-compliant CBV-optimized protocols resulted in rank variations within the cohort (Spearman's ρ = 0.83-0.89, i.e. 31%-21% rank variation). Treatment-naïve glioblastoma exhibited lower parameter-matched PSR compared to the external cohorts of treatment-naïve primary CNS lymphomas (PCNSL) (p<0.0001), supporting a role of synthetic DSC for multicenter comparisons. Acquisition factors highly impacted PSR, and nrCBV without leakage correction also showed parameter-dependence, although less pronounced. However, this dependence was remarkably mitigated by post-hoc leakage correction.

Conclusions: Dynamic SAGE-EPI allows for simultaneous generation of CBV-optimized and PSR-optimized DSC data with one acquisition and a single contrast injection, facilitating the use of a single perfusion protocol for all DSC applications. This approach may also be useful for comparisons of perfusion metrics across heterogeneous multicenter datasets, as it facilitates post-hoc harmonization.

Background and purpose: Autoimmune rheumatic diseases (AIRD) can cause intracranial artery stenosis (ICAS) and lead to stroke. This study aimed to characterize patients with ICAS associated with AIRD.

Materials and methods: Using data from a high-resolution MR imaging database, we retrospectively reviewed patients with AIRD with ICAS. Stratification into vasculitis, atherosclerosis, and mixed atherovasculitis subtypes was based on imaging findings, followed by a comparative analysis of clinical characteristics and outcomes across these subgroups.

Results: Among 139 patients (mean, 45.1 [SD, 17.3] years; 64.7% women), 56 (40.3%) were identified with vasculitis; 57 (41.0%), with atherosclerosis; and 26 (18.7%), with mixed atherovasculitis. The average interval from AIRD onset to high-resolution MRI was 5 years. Patients with vasculitis presented at a younger age of AIRD onset (mean, 34.5 [SD, 19.4] years), nearly 10 years earlier than other groups (P = .010), with a higher artery occlusion incidence (44.6% versus 21.1% and 26.9%, P = .021). Patients with atherosclerosis showed the highest cardiovascular risk factor prevalence (73.7% versus 48.2% and 61.5%, P = .021) but fewer intracranial artery wall enhancement instances (63.2% versus 100% in others, P < .001). The mixed atherovasculitis group, predominantly men (69.2% versus 30.4% and 24.6%, P < .001), exhibited the most arterial involvement (5 arteries per person versus 3 and 2, P = .001). Over an average 21-month follow-up, 23 (17.0%) patients experienced stroke events and 8 (5.9%) died, with the mixed atherovasculitis group facing the highest risk of stroke events (32.0%) and the highest mortality (12.0%).

Conclusions: Intracranial arteries are injured and lead to heterogeneous disease courses when exposed to AIRD and cardiovascular risk factors. While atherosclerosis acceleration is common, vasculitis may further contribute to the early development of occlusion and multiple artery involvement. Varied intracranial arteriopathies may result in different outcomes.

Background and purpose: Proximal protection devices, such as TransCarotid Artery Revascularization (TCAR, SilkRoad Medical, Sunnyvale), aim to yield better outcomes in carotid artery stenting (CAS) than distal protection devices by preventing plaque embolization to the brain. However, transfemoral catheters may not fully reverse flow from the external carotid artery (ECA) to the internal carotid artery (ICA). We assess a new balloon-sheath device, Femoral Flow Reversal Access for Carotid Artery Stenting (FFRACAS), for this purpose.

Materials and methods: The FFRACAS prototype (ID = 0.117"; L=80cm) was compared to TCAR (ID=0.104", L=30cm) and MoMa (Medtronic, Minneapolis; ID=0.083", L=90cm) in a pulsatile flow model with blood simulant at 800mL/min. MoMa was used according to labeled instructions, with both CCA and ECA balloon inflation, without CCA-femoral vein shunt placement, and in an off-label fashion with single balloon occlusion in the CCA and shunt. Flow rates of the ICA, ECA, and shunt, when applicable, were monitored during CAS stages: CCA flow arrest, shunt activation, and stent delivery. Experiments were conducted under two ECA inflow conditions (-10 and -20 mL/min). Statistical comparison of ICA flow rates was conducted using ANOVA and Tukey's post-hoc tests.

Results: MoMa's on-label use maintained retrograde ICA flow (-0.3 mL/min) throughout CAS. Upon shunt activation, TCAR and FFRACAS reversed ICA flow similarly under low ECA inflow (ICA=-5.10 mL/min vs. -4.83 mL/min; p=0.349), but neither achieved ICA flow reversal under high ECA inflow or during stent delivery. MoMa off-label use failed to reverse ICA flow.

Conclusions: FFRACAS presents a potential alternative to TCAR, achieving similar degrees of flow reversal from a transfemoral approach to that achieved with the transcarotid approach. The MoMa system reliably prevents anterograde flow in ICA during CAS.

Abbreviations: CAS = Carotid Artery Stenting; TCAR = Transcarotid Arterial Revascularization; CCA = Common Carotid Artery; ICA = Internal Carotid Artery; ECA = External Carotid Artery; VA = Vertebral Artery; FFRACAS = Femoral Flow Reversal Access for Carotid Artery Stenting; ID = Inner Diameter; OD = Outer Diameter.

Background and purpose: Early identification of malignant cerebral edema (MCE) in patients with acute ischemic stroke is crucial for timely interventions. We aimed to identify regions critically associated with MCE using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) to evaluate the association between location-specific-net water uptake (NWU) and MCE.

Materials and methods: This multicentre, retrospective cohort study included patients with acute ischemic stroke following large anterior circulation occlusion. The ASPECTS was determined by RAPID ASPECTS software. ASPECTS-NWU and Region-NWU were calculated automatically by comparing the Hounsfield units values in the ischemic and contralateral regions. Critical ASPECTS MCE regions and Region-NWU were evaluated by multivariate logistic regression and the areas under the receiver operating characteristic curves (AUCs).

Results: The study included 513 patients. Multivariate analysis showed that the ASPECTS insula (OR=2.49; 95% CI, 1.44-4.31) and M5 (OR=1.59; 95% CI, 1.11-3.41) regions were significantly associated with MCE. After adjustment, only the insula (OR=2.34; 95% CI, 1.23-4.45) was independently associated with MCE. Univariable ROC analysis found AUCs for Insula-NWU (AUC, 0.70; 95% CI, 0.65- 0.76)and ASPECTS-NWU (AUC, 0.64; 95% CI, 0.58-0.70) .The Insula-NWU had better diagnostic power than ASPECTS-NWU (DeLong test; P=0.01). A multivariate regression model that combined the NIHSS, ASPECTS, insula involvement, and Insula-NWU had good discriminatory power (AUC=0.80; 95% CI, 0.74-0.86) and better diagnostic power than Insula-NWU (DeLong test; P<0.01).

Conclusions: Brief statement directed to the stated purpose or hypothesis; no references should be cited.The insula region is critical for MCE, and Insula-NWU has better prediction efficacy than ASPECTS-NWU. This method does not rely on advanced imaging, facilitating rapid assessment in emergencies.

Abbreviations: ASPECTS = the Alberta Stroke Program Early Computed Tomography Score; AUC= the areas under the receiver operating characteristic curve; CT=computed tomography; CTP=CT perfusion; HU = hounsfield unit; MCE = malignant cerebral edema; NCCT=non-contrast Computed Tomography; NWU = net water uptake; ROC = receiver operating characteristic curve.

Prolonged imaging times and motion sensitivity at 7T necessitate advancements in image acceleration techniques. This study evaluates a 7T deep-learning (DL)-based image reconstruction using a deep neural network trained on 7T data, applied to T2-weighted turbo spin echo imaging. Raw k-space data from 30 consecutive clinical 7T brain MRI patients was reconstructed using both DL and standard methods. Qualitative assessments included overall image quality, artifacts, sharpness, structural conspicuity, and noise level, while quantitative metrics evaluated contrast-to-noise ratio (CNR) and image noise. DL-based reconstruction consistently outperformed standard methods across all qualitative metrics (p<0.001), with a mean CNR increase of 50.8% [95% CI: 43.0-58.6%] and a mean noise reduction of 35.1% [95% CI: 32.7-37.6%]. These findings demonstrate that DL-based reconstruction at 7T significantly enhances image quality without introducing adverse effects, offering a promising tool for addressing the challenges of ultra-high-field MRI.ABBREVIATIONS: CNR = contrast-to-noise ratio; DL = deep learning; GRAPPA = GeneRalized Autocalibrating Partially Parallel Acquisitions; IQR = interquartile range; MNI = Montreal Neurological Institute; SD = standard deviation.

The magnetic fields of the MR environment present unique safety challenges. Medical implants and retained foreign bodies can prevent patients from undergoing MR imaging due to interactions between the magnetic fields of the MR environment and the implant or foreign body. These hazards can be addressed through careful MR safety screening and MR examination customization, often allowing these patients with implants to undergo management-altering MR imaging. However, mitigating these risks takes additional time, expertise, and effort. Effective in 2025, this additional work is formally acknowledged with a new series of CPT® codes to report the work of assessing and addressing safety concerns associated with implants and foreign bodies in the MR environment. This user guide provides guidance on how to report these codes so physician led MR safety teams can be appropriately reimbursed for the additional work performed in preparing patients with implants or foreign bodies for MR imaging.ABBREVIATIONS: ACR = American College of Radiology™; ASNR = American Society of Neuroradiology; CPT® = Common Procedural Terminology; QHP = Qualified Healthcare Professional; ARRT® = American Registry of Radiologic Technologists; ABMRS = American Board of Magnetic Resonance Safety; MRSO = Magnetic Resonance Safety Officer; MRMD = Magnetic Resonance Medical Director; MRSE = Magnetic Resonance Safety Expert.

Background and purpose: Timely reporting of CTA exams impacts management of acute vascular pathology such as large vessel occlusions, arterial dissection, and ruptured aneurysm as well as a variety of acute non-vascular pathologies. In this study, we examine potential modifiable factors impacting the timeliness of CTA reporting performed in stroke code activations.

Materials and methods: Observational study of stroke code CTA head and neck exams performed at a single health system (3 emergency departments, 1550 inpatient beds) over four years (1/1/2019-12/31/2023). Patient age, patient sex, care setting, time of year, shift type, trainee/attending radiologist characteristics, report factors, and number of CTAs performed within the preceding hour were considered potential factors impacting the turnaround time (TAT) of stroke code CTAs. Descriptive statistics, univariate regression, and multivariate regression were used to estimate the impact on reporting TAT.

Results: 8422 stroke code CTA exams were performed. Median TAT was 29 minutes (IQR 18-48). Median TAT by individual attending radiologists varied from 15 to 40 minutes (median of medians 29 minutes [IQR 26-34.5]). Univariate regression analyses found lower patient age, emergency department setting, time later in the academic year, non-business hours, specific individual radiologists/trainees, solo-reporting by attending radiologists, use of preliminary reports, and fewer stroke codes within the preceding hour to all be associated with shorter TATs (all p<0.05). Adjusting for patient, logistical, and radiologist-level factors in a multivariate regression model, the greatest impact on TAT was seen with variation in individual attending radiologists (adjusted coefficients -2.6 to +43.3 minutes) and trainees (-49.6 to +109.0 minutes); reporting CTAs without a trainee and release of preliminary reports prior to final sign were associated with faster TATs (-11.4 and -24.7 minutes, respectively). Each stroke CTA within the preceding hour was associated with only a 4.0-minute increase in TAT. Secondary analyses suggested that previewing of cases during active scanning and use of "structured" reports correlates with favorable impact on TAT among attending radiologists (both p<0.05).

Conclusions: Radiologist and trainee-level timeliness in stroke CTA reporting varies widely. Interventions aimed at improving workflow efficiency for both trainees and attending radiologists could improve timeliness of reporting.

Abbreviations: IQR, interquartile range; TAT, turnaround time; TFR, time to final report.

Background and purpose: Accurately identifying patients with CSF-venous fistulas (CVF) causing spontaneous intracranial hypotension, is a diagnostic dilemma. This conundrum underscores the need for a CVF biomarker to help select who should undergo an invasive myelogram for further diagnostic work-up. β-trace protein (BTP) is the most abundant CNS-derived protein in the CSF and, therefore, is a potential venous biomarker for CVF detection. The purpose of our study was to measure venous BTP levels as a potential CVF biomarker.

Materials and methods: We prospectively enrolled 14 patients with CVFs and measured the BTP in venous blood samples from the paraspinal veins near the CVF and compared those levels with those in the peripheral blood. Myelograms used initially to identify the CVF were evaluated for technique, CVF laterality, CVF level, and the venous drainage pattern. Patient sex and age and symptom duration were also collected. Brain MR images were reviewed for Bern scores. We also measured the peripheral blood BTP levels in 20 healthy controls.

Results: In patients with CVF, the mean BTP level near the CVF was 54.5% higher (0.760 [SD, 0.673] mg/L versus 0.492 [SD, 0.095] mg/L; P = .069) compared with peripheral blood. Nine (64.3%) patients with CVFs had a higher paraspinal BTP level than peripheral BTP level. The 20 control patients had a higher mean peripheral BTP level of 0.720 (SD, 0.191) mg/L compared with patients with CVF (P < .001).

Conclusions: We found that venous blood at the site of the CVF had higher BTP values compared with peripheral blood in most but not all patients with CVF. This finding may reflect the intermittent leaking nature of CVF. Additionally, we found that patients with CVF had a lower peripheral blood BTP level compared with healthy controls. BTP requires further evaluation as a potential CVF biomarker.