AJNR. American journal of neuroradiology最新文献

Background and purpose: Overuse of CT-based cerebrovascular imaging in the emergency department and inpatient settings, notably CTA of the head and neck for minor and nonfocal neurologic presentations, stresses imaging services and exposes patients to radiation and contrast. Furthermore, such CT-based imaging is often insufficient for definitive diagnosis, necessitating additional MR imaging. Recent advances in fast MRI may allow timely assessment and a reduced need for head and neck CTA in select populations.

Materials and methods: We identified inpatients or patients in the emergency department who underwent CTAHN (including noncontrast and postcontrast head CT, with or without CTP imaging) followed within 24 hours by a 3T MRI study that included a 2.5-minute unenhanced multicontrast sequence (NeuroMix) and a 5-minute intracranial time of flight MRA) during a 9-month period (April to December 2022). Cases were classified by 4 radiologists in consensus as to whether NeuroMix and NeuroMix + MRA detected equivalent findings, detected unique findings, or missed findings relative to CTAHN.

Results: One hundred seventy-four cases (mean age, 67 [SD, 16] years; 56% female) met the inclusion criteria. NeuroMix alone and NeuroMix + MRA protocols were determined to be equivalent or better compared with CTAHN in 71% and 95% of patients, respectively. NeuroMix always provided equivalent or better assessment of the brain parenchyma, with unique findings on NeuroMix and NeuroMix + MRA in 35% and 36% of cases, respectively, most commonly acute infarction or multiple microhemorrhages. In 8/174 cases (5%), CTAHN identified vascular abnormalities not seen on the NeuroMix + MRA protocol due to the wider coverage of the cervical arteries by CTAHN.

Conclusions: A fast MR imaging protocol consisting of NeuroMix + MRA provided equivalent or better information compared with CTAHN in 95% of cases in our population of patients with an acute neurologic presentation. The findings provide a deeper understanding of the benefits and challenges of a fast unenhanced MR-first approach with NeuroMix + MRA, which could be used to design prospective trials in select patient groups, with the potential to reduce radiation dose, mitigate adverse contrast-related patient and environmental effects, and lessen the burden on radiologists and health care systems.

Background and purpose: Photon-counting detector CT (PCD-CT) is now clinically available and offers ultra-high-resolution (UHR) imaging. Our purpose was to prospectively evaluate the relative image quality and impact on diagnostic confidence of head CTA images acquired by using a PCD-CT compared with an energy-integrating detector CT (EID-CT).

Materials and methods: Adult patients undergoing head CTA on EID-CT also underwent a PCD-CT research examination. For both CT examinations, images were reconstructed at 0.6 mm by using a matched standard resolution (SR) kernel. Additionally, PCD-CT images were reconstructed at the thinnest section thickness of 0.2 mm (UHR) with the sharpest kernel, and denoised with a deep convolutional neural network (CNN) algorithm (PCD-UHR-CNN). Two readers (R1, R2) independently evaluated image quality in randomized, blinded fashion in 2 sessions, PCD-SR versus EID-SR and PCD-UHR-CNN versus EID-SR. The readers rated overall image quality (1 [worst] to 5 [best]) and provided a Likert comparison score (-2 [significantly inferior] to 2 [significantly superior]) for the 2 series when compared side-by-side for several image quality features, including visualization of specific arterial segments. Diagnostic confidence (0-100) was rated for PCD versus EID for specific arterial findings, if present.

Results: Twenty-eight adult patients were enrolled. The volume CT dose index was similar (EID: 37.1 ± 4.7 mGy; PCD: 36.1 ± 4.0 mGy). Overall image quality for PCD-SR and PCD-UHR-CNN was higher than EID-SR (eg, PCD-UHR-CNN versus EID-SR: 4.0 ± 0.0 versus 3.0 ± 0.0 (R1), 4.9 ± 0.3 versus 3.0 ± 0.0 (R2); all P values < .001). For depiction of arterial segments, PCD-SR was preferred over EID-SR (R1: 1.0-1.3; R2: 1.0-1.8), and PCD-UHR-CNN over EID-SR (R1: 0.9-1.4; R2: 1.9-2.0). Diagnostic confidence of arterial findings for PCD-SR and PCD-UHR-CNN was significantly higher than EID-SR: eg, PCD-UHR-CNN versus EID-SR: 93.0 ± 5.8 versus 78.2 ± 9.3 (R1), 88.6 ± 5.9 versus 70.4 ± 5.0 (R2); all P values < .001.

Conclusions: PCD-CT provides improved image quality for head CTA images compared with EID-CT, both when PCD and EID reconstructions are matched, and to an even greater extent when PCD-UHR reconstruction is combined with a CNN denoising algorithm.

Background and purpose: DSC-MR imaging can be used to generate fractional tumor burden (FTB) maps via application of relative CBV thresholds to spatially differentiate glioblastoma recurrence from posttreatment radiation effects (PTRE). Image-localized histopathology was previously used to validate FTB maps derived from a reference DSC-MR imaging protocol by using preload, a moderate flip angle (MFA, 60°), and postprocessing leakage correction. Recently, a DSC-MR imaging protocol with a low flip angle (LFA, 30°) with no preload was shown to provide leakage-corrected relative CBV (rCBV) equivalent to the reference protocol. This study aimed to identify the rCBV thresholds for the LFA protocol that generate the most accurate FTB maps, concordant with those obtained from the reference MFA protocol.

Materials and methods: Fifty-two patients with grade-IV glioblastoma who had prior surgical resection and received chemotherapy and radiation therapy were included in the study. Two sets of DSC-MR imaging data were collected sequentially first by using LFA protocol with no preload, which served as the preload for the subsequent MFA protocol. Standardized relative CBV maps (sRCBV) were obtained for each patient and coregistered with the anatomic postcontrast T1-weighted images. The reference MFA-based FTB maps were computed by using previously published sRCBV thresholds (1.0 and 1.56). A receiver operating characteristics (ROC) analysis was conducted to identify the optimal, voxelwise LFA sRCBV thresholds, and the sensitivity, specificity, and accuracy of the LFA-based FTB maps were computed with respect to the MFA-based reference.

Results: The mean sRCBV values of tumors across patients exhibited strong agreement (concordance correlation coefficient = 0.99) between the 2 protocols. Using the ROC analysis, the optimal lower LFA threshold that accurately distinguishes PTRE from tumor recurrence was found to be 1.0 (sensitivity: 87.77%; specificity: 90.22%), equivalent to the ground truth. To identify aggressive tumor regions, the ROC analysis identified an upper LFA threshold of 1.37 (sensitivity: 90.87%; specificity: 91.10%) for the reference MFA threshold of 1.56.

Conclusions: For LFA-based FTB maps, an sRCBV threshold of 1.0 and 1.37 can differentiate PTRE from recurrent tumors. FTB maps aid in surgical planning, guiding pathologic diagnosis and treatment strategies in the recurrent setting. This study further confirms the reliability of single-dose LFA-based DSC-MR imaging.

Background and purpose: Quantitative susceptibility mapping has been proposed to assess intraplaque hemorrhage (IPH) in the carotid artery. The purpose of this study was to compare the diagnostic accuracy of preoperative quantitative susceptibility mapping with that of the conventional T1-weighed 3D-FSE sequence for detecting IPH in cervical ICA stenosis in patients undergoing carotid endarterectomy by using histology as the reference standard.

Materials and methods: Carotid T1-weighted 3D-FSE and QSM images were obtained from 16 patients with cervical ICA stenosis before carotid endarterectomy. Relative signal intensity and susceptibility of the ICA were measured on 3 axial images, including the location of most severe stenosis on T1-weighted 3D-FSE and quantitative susceptibility mapping images, respectively. Three transverse sections of carotid plaques excised by carotid endarterectomy, which corresponded with images on MR imaging, were stained with H&E, antibody against glycophorin A, and Prussian blue, and the relative area of histologic IPH was calculated.

Results: The correlation coefficient was significantly greater between susceptibility and relative area-histologic IPH (ρ = 0.691) than between relative signal intensity and relative area-histologic IPH (ρ = 0.413; P = .0259). The areas under the receiver operating characteristic curves for detecting histologic sections consisting primarily of IPH (relative area-histologic IPH > 40.7%) tended to be greater for susceptibility (0.964) than for T1WI FSE-relative signal intensity (0.811). Marginal homogeneity was observed between susceptibility and histologic sections consisting primarily of IPH (P = .0412), but not between T1-weighted FSE-relative signal intensity and histologic sections consisting primarily of IPH (P = .1824).

Conclusions: Pre-carotid endarterectomy quantitative susceptibility mapping detects histologic IPH in cervical ICA stenosis more accurately than preoperative T1-weighted 3D-FSE imaging.

Radiographic assessment plays a crucial role in the management of patients with central nervous system (CNS) tumors, aiding in treatment planning and evaluation of therapeutic efficacy by quantifying response. Recently, an updated version of the Response Assessment in Neuro-Oncology (RANO) criteria (RANO 2.0) was developed to improve upon prior criteria and provide an updated, standardized framework for assessing treatment response in clinical trials for gliomas in adults. This article provides an overview of significant updates to the criteria including (1) the use of a unified set of criteria for high and low grade gliomas in adults; (2) the use of the post-radiotherapy MRI scan as the baseline for evaluation in newly diagnosed high-grade gliomas; (3) the option for the trial to mandate a confirmation scan to more reliably distinguish pseudoprogression from tumor progression; (4) the option of using volumetric tumor measurements; and (5) the removal of subjective non-enhancing tumor evaluations in predominantly enhancing gliomas (except for specific therapeutic modalities). Step-by-step pragmatic guidance is hereby provided for the neuroradiologist and imaging core lab involved in operationalization and technical execution of RANO 2.0 in clinical trials, including the display of representative cases and in-depth discussion of challenging scenarios.

Background: Intrameatal vascular loops (IVL) entering the internal auditory meatus (IAM) and neurovascular contact (NVC) with the vestibulo-cochlear nerve (CN VIII) have been proposed to have a relationship with audio-vestibular symptoms.

Purpose: This systematic review and meta-analysis aimed to determine whether the presence of IVLs and CN VIII NVC on magnetic resonance imaging (MRI) is associated with tinnitus, sensorineural hearing loss (SNHL) or vertigo and any specific subtypes.

Data sources: All studies comparing the presence of IVL or CN VIII NVC in ears with these audio-vestibular symptoms and controls were identified through MEDLINE, EMBASE, Web of Science Core Collection, Scopus and Cochrane Register of Controlled Trials databases.

Study selection: 16 studies and 3,455 ears (1526 symptomatic ears and 1929 control ears) were included.

Data analysis: Meta-analysis was performed using a bivariate random effects model. Pooled odds ratios (ORs) were calculated, and heterogeneity was evaluated with Cochran's Q test with statistical significance defined as p<0.05.

Data synthesis: There was no significant association between the presence of undefined tinnitus or SNHL and that of IVL (OR 0.90 95% CI 0.47, 1.70; OR 0.67, 95% CI 0.36, 1.25) or CN VIII NVC (OR 1.15, 95% CI 0.68, 1.95; OR 0.89, 95% CI 0.33, 2.40). However, the subgroup of sudden onset SNHL was associated with IVL (OR 1.34, 95% CI 1.04, 1.73) (p=0.02). There was no significant difference in the prevalence of IVL (OR 0.97, 95% CI 0.64, 1.48) or CN VIII NVC (OR 0.99, 95% CI 0.42, 2.32) between ears with undefined vertigo and control ears. However, there was an association between the presence of CN VIII NVC and the specific diagnosis of vestibular paroxysmia (OR 13.19, 95% CI 2.09, 83.16) (p=0.006).

Limitations: Our meta-analysis is limited by selection bias, small number of eligible studies and moderate heterogeneity.

Conclusions: IVL or CN VIII NVC on MRI are unrelated to symptoms of undefined tinnitus, SNHL and vertigo. However, CN VIII NVC is associated with vestibular paroxysmia whilst IVL is associated with sudden onset SNHL.

Abbreviations: AICA = anterior inferior cerebellar artery, CI = confidence interval, CN = cranial nerve, CPA = cerebellopontine angle, IAM = internal auditory meatus, NVC = neurovascular contact, OR = odds ratio, SNHL = sensorineural hearing loss, SoSNHL = sudden onset sensorineural hearing loss.

Background and purpose: Quantitative susceptibility mapping is an emerging method for characterizing tissue composition and studying myelination and iron deposition. However, accurate assessment of myelin and iron content in the newborn brain using this method is challenging because these two susceptibility sources of opposite signs (myelin, negative; iron, positive) occupy the same voxel, with minimal and comparable content in both sources. In this study, susceptibilities were measured in the normal newborn brain using susceptibility source separation.

Materials and methods: Sixty-nine healthy newborns without clinical indications were prospectively recruited for MRI. All newborns underwent gradient echo imaging for quantitative susceptibility mapping. Positive (paramagnetic) and negative (diamagnetic) susceptibility sources were separated using additional information from R2* with linear modeling performed for the newborn brain. Average susceptibility maps were generated by normalizing all susceptibility maps to an atlas space. Mean regional susceptibility measurements were obtained in the cortical GM, WM, deep GM, caudate nucleus, putamen, globus pallidus, thalamus, and the four brain lobes.

Results: A total of sixty-five healthy newborns (mean postmenstrual age, 42.8 ± 2.3 weeks; 34 females) were studied. The negative susceptibility maps visually demonstrated high signals in the thalamus, brainstem and potentially myelinated WM regions, whereas the positive susceptibility maps depicted high signals in the GM compared to all WM regions, including both myelinated and unmyelinated WM. The WM exhibited significantly lower mean positive susceptibility and significantly higher mean negative susceptibility than cortical GM and deep GM. Within the deep GM, the thalamus showed a significantly lower mean negative susceptibility than the other nuclei, and the putamen and globus pallidus showed significant associations with newborn age in positive and/or negative susceptibility. Among the four brain lobes, the occipital lobe showed a significantly higher mean positive susceptibility and a significantly lower mean negative susceptibility than the frontal lobe.

Conclusions: This study demonstrates regional variations and temporal changes in positive and negative susceptibilities of the newborn brain, potentially associated with myelination and iron deposition patterns in normal brain development. It suggests that quantitative susceptibility mapping with source separation may be used for early identification of delayed myelination or iron deficiency.

Abbreviations: CGM = cortical gray matter; DGM = deep gray matter; PMA = postmenstrual age; QSM = quantitative susceptibility mapping.

Atypical parkinsonian syndromes, also known as Parkinson-plus syndromes, are a heterogeneous group of movement disorders, including dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), multisystem atrophy (MSA), and corticobasal degeneration (CBD). This review highlights the characteristic structural, functional, and molecular imaging features of these complex disorders. DLB typically demonstrates parieto-occipital hypometabolism with involvement of the cuneus on FDG-PET, whereas dopaminergic imaging, such as [¹²³I]-FP-CIT SPECT (DaTscan) or fluorodopa (FDOPA)-PET, can be utilized as an adjunct for diagnosis. PSP typically shows midbrain atrophy on structural imaging, whereas FDG-PET may be useful to depict frontal lobe hypometabolism and tau-PET confirms underlying tauopathy. MSA typically demonstrates putaminal or cerebellar atrophy, whereas FDG-PET highlights characteristic nigrostriatal or olivopontocerebellar hypometabolism, respectively. Finally, CBD typically shows asymmetric atrophy in the superior parietal lobules and corpus callosum, whereas FDG and tau-PET demonstrate asymmetric hemispheric and subcortical involvement contralateral to the side of clinical deficits. Additional advanced neuroimaging modalities and techniques described may assist in the diagnostic work-up or are promising areas of emerging research.

SUMMARY: Spinal CSF leak care has considerably evolved over the past several years due to pivotal advances in its diagnosis and treatment. To the reader of the AJNR, it has been impossible to miss the exponential increase in groundbreaking research on spinal CSF leaks and spontaneous intracranial hypotension (SIH). While many clinical specialties have contributed to these successes, the neuroradiologist has been instrumental in driving this transformation due to innovations in non-invasive imaging, novel myelographic techniques, and imageguided therapies. In this editorial, we will delve into the exciting advancements in spinal CSF leak diagnosis and treatment and celebrate the vital role of the neuroradiologist at the forefront of this revolution, with particular attention to CSF leak related work published in the AJNR.ABBREVIATIONS: SIH = spontaneous intracranial hypotension; CVF = CSF-venous fistula; CTM = CT myelography; DSM = digital subtraction myelography; CB-CTM = conebeam CT myelography; PCD-CT = photon counting detector CT.

Background and purpose: Vertebral compression fractures may indicate osteoporosis but are underdiagnosed and underreported by radiologists. We have developed an ensemble of vertebral body (VB) segmentation models for lateral radiographs as a critical component of an automated, opportunistic screening tool. Our goal is to detect the approximate location of thoracic and lumbar VBs, including fractured vertebra, on lateral radiographs.

Materials and methods: The Osteoporotic Fractures in Men Study (MrOS) data set includes spine radiographs of 5994 men aged ≥65 years from 6 clinical centers. Two segmentation models, U-Net and Mask-RCNN (Region-based Convolutional Neural Network), were independently trained on the MrOS data set retrospectively, and an ensemble was created by combining them. Primary performance metrics for VB detection success included precision, recall, and F1 score for object detection on a held-out test set. Intersection over union (IoU) and Dice coefficient were also calculated as secondary metrics of performance for the test set. A separate external data set from a quaternary health care enterprise was acquired to test generalizability, comprising diagnostic clinical radiographs from men and women aged ≥65 years.

Results: The trained models achieved F1 score of U-Net = 83.42%, Mask-RCNN = 86.30%, and ensemble = 88.34% in detecting all VBs, and F1 score of U-Net = 87.88%, Mask-RCNN = 92.31%, and ensemble = 97.14% in detecting severely fractured vertebrae. The trained models achieved an average IoU per VB of 0.759 for U-Net and 0.709 for Mask-RCNN. The trained models achieved F1 score of U-Net = 81.11%, Mask-RCNN = 79.24%, and ensemble = 87.72% in detecting all VBs in the external data set.

Conclusions: An ensemble model combining predictions from U-Net and Mask-RCNN resulted in the best performance in detecting VBs on lateral radiographs and generalized well to an external data set. This model could be a key component of a pipeline to detect fractures on all vertebrae in a radiograph in an automated, opportunistic screening tool under development.