Clinical Neuroradiology最新文献

Purpose: To investigate the shared and distinct alterations in hippocampal subfield atrophy and functional connectivity (FC) in Parkinson's disease (PD) with normal cognition (PD-NC), PD with mild cognitive impairment (PD-MCI) and unspecified MCI (U-MCI).

Methods: A total of 294 participants were included from two centers (30 PD-NC, 86 PD-MCI, 76 U-MCI, and 102 healthy controls (HC)). Comparisons of hippocampal subfield volumes were conducted among groups. Seed-based FC was calculated to assess abnormalities between hippocampal subfields and cortical regions.

Results: Compared to HC, PD-NC group showed volumetric reductions in the right cornu ammonis (CA) 2/3, granule cell layer of the dentate gyrus (GC-DG), and CA4 subfields, while PD-MCI group exhibited bilateral volumetric reductions in the same subfields. PD-MCI patients exhibited increased FC between the bilateral GC-DG/CA4 subfield and the posterior default mode network (pDMN), as well as between the right GC-DG/CA4 subfield and the calcarine, in comparison to PD-NC. U‑MCI patients displayed smaller volume in the right CA4 compared to HC. Decreased FC of the hippocampus with the widespread visual network was observed in the PD-MCI group compared to the U‑MCI group.

Conclusions: PD-MCI is associated with structural vulnerability of hippocampal subfields in the CA2/3, GC-DG, and CA4 subfields, impacting FC with pDMN and visual network. Smaller scope of hippocampal subfields atrophy but weaker hippocampus-visual network FC abnormalities in U‑MCI relative to PD-MCI may suggest distinct progression mechanisms between these two conditions.

Background: Clinical evaluation of Artificial Intelligence (AI)-based Precise Image (PI) algorithm in brain imaging remains limited. PI is a deep-learning reconstruction (DLR) technique that reduces image noise while maintaining a familiar Filtered Back Projection (FBP)-like appearance at low doses. This study aims to compare PI, Iterative Reconstruction (IR), and FBP-in improving image quality and enhancing lesion detection in 1.0 mm thin-slice brain computed tomography (CT) images.

Methods: A retrospective analysis was conducted on brain non-contrast CT scans from August to September 2024 at our institution. Each scan was reconstructed using four methods: routine 5.0 mm FBP (Group A), thin-slice 1.0 mm FBP (Group B), thin-slice 1.0 mm IR (Group C), and thin-slice 1.0 mm PI (Group D). Subjective image quality was assessed by two radiologists using a 4- or 5‑point Likert scale. Objective metrics included contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and image noise across designated regions of interest (ROIs).

Results: 60 patients (65.47 years ± 18.40; 29 males and 31 females) were included. Among these, 39 patients had lesions, primarily low-density lacunar infarcts. Thin-slice PI images demonstrated the lowest image noise and artifacts, alongside the highest CNR and SNR values (p < 0.001) compared to Groups A, B, and C. Subjective assessments revealed that both PI and IR provided significantly improved image quality over routine FBP (p < 0.05). Specifically, Group D (PI) achieved superior lesion conspicuity and diagnostic confidence, with a 100% detection rate for lacunar lesions, outperforming Groups B and A.

Conclusions: PI reconstruction significantly enhances image quality and lesion detectability in thin-slice brain CT scans compared to IR and FBP, suggesting its potential as a new clinical standard.

Purpose: We evaluated a dedicated dose-reduced UHR-CT for head and neck imaging, combined with a novel deep learning reconstruction algorithm to assess its impact on image quality and radiation exposure.

Methods: Retrospective analysis of ninety-eight consecutive patients examined using a new body weight-adapted protocol. Images were reconstructed using adaptive iterative dose reduction and advanced intelligent Clear-IQ engine with an already established (DL-1) and a newly implemented reconstruction algorithm (DL-2). Additional thirty patients were scanned without body-weight-adapted dose reduction (DL-1-SD). Three readers evaluated subjective image quality regarding image quality and assessment of several anatomic regions. For objective image quality, signal-to-noise ratio and contrast-to-noise ratio were calculated for temporalis and masseteric muscle and the floor of the mouth. Radiation dose was evaluated by comparing the computed tomography dose index (CTDIvol) values.

Results: Deep learning-based reconstruction algorithms significantly improved subjective image quality (diagnostic acceptability: DL‑1 vs AIDR OR of 25.16 [6.30;38.85], p < 0.001 and DL‑2 vs AIDR 720.15 [410.14;> 999.99], p < 0.001). Although higher doses (DL-1-SD) resulted in significantly enhanced image quality, DL‑2 demonstrated significant superiority over all other techniques across all defined parameters (p < 0.001). Similar results were demonstrated for objective image quality, e.g. image noise (DL‑1 vs AIDR OR of 19.0 [11.56;31.24], p < 0.001 and DL‑2 vs AIDR > 999.9 [825.81;> 999.99], p < 0.001). Using weight-adapted kV reduction, very low radiation doses could be achieved (CTDIvol: 7.4 ± 4.2 mGy).

Conclusion: AI-based reconstruction algorithms in ultra-high resolution head and neck imaging provide excellent image quality while achieving very low radiation exposure.

Purpose: To determine the radiological prevalence of superior semicircular canal (SSC) dehiscence in a Japanese cohort using ultra-high-resolution (0.2 mm slice thickness) photon-counting detector CT (PCD-CT) and compare it with historical data from cadaveric and conventional CT studies.

Methods: This study involved a retrospective analysis of 402 temporal bones from consecutive 201 patients (age range 0-87 years; mean 41.0 ± 26.5 years) who underwent temporal bone PCD-CT for various otologic indications, none of whom had a pre-existing diagnosis of superior semicircular canal dehiscence syndrome (SSCDS). SSC bone thickness was measured, and the presence of dehiscence or thinning was assessed using multiplanar reconstructions, primarily in the Pöschl plane. For cases with identified dehiscence or thinning, a retrospective review of clinical and audiological data was performed.

Results: The mean thickness of the bone overlying the SSC was 0.87 ± 0.50 mm (range 0-3.52 mm). A definite dehiscence was identified in only 1 of the 402 temporal bones, yielding a radiological prevalence of 0.25% (95% CI: 0.00%-1.54%). Significant thinning of the SSC roof, where the bone was present but too thin to be resolved by the measurement caliper, was noted in an additional 12 temporal bones (2.99%, 95% CI: 1.66%-5.20%). Clinical review revealed that the single case of dehiscence was asymptomatic, and in the thinning cases, otologic symptoms were attributable to co-existing pathologies.

Conclusions: The radiological prevalence of SSC dehiscence identified with 0.2 mm PCD-CT is substantially lower than that reported by most conventional CT studies and closely approximates the true anatomical prevalence of 0.4-0.6% established in cadaveric studies. This finding suggests that the ultra-high spatial resolution of PCD-CT significantly reduces or eliminates false-positive findings attributable to partial volume effects, representing a new benchmark for the accurate radiological assessment of SSCDS.

Introduction: Scatter radiation during interventional neuroradiological (INR) procedures is potentially harmful to the operator and cath-lab staff. Enhanced radiation protection devices (ERPDs) aim to improve safety by minimizing scatter radiation in addition to standard and personal protective equipment (PPE). This study evaluated the efficacy of a novel ERPD in INR.

Methods: Radiation exposure of the main operator was estimated by measuring the local dose rate at the examination position. An anthropomorphic patient whole body phantom was used simulating a standard INR procedure. The relative dose reductions were determined for the following settings: a) MasterPeace (Texray AB, Sweden) combined with ceiling-suspended lead screen (Mavig, Germany) compared to no shielding. b) MasterPeace combined with ceiling-suspended lead screen, compared to standard radiation protection consisting of a table-side curtain for lower body protection (Kenex, UK) and ceiling-suspended lead screen. Scatter radiation was measured at various operator heights (70, 130 and 160 cm) across seven routine projection angles using a biplane angio-suite (Artis zee, Siemens Healthineers, Germany).

Results: (a) The mean scatter radiation shielding effect was 98.5% compared to no shielding across all measured heights and angular projections when used in combination with a ceiling-suspended lead screen. (b) The mean scatter radiation shielding effect was 79.7% compared to standard radiation protection for all measured heights and angular projections. The shielding efficacy ranged from 93.1% for the PA projection to 31.8% for LAO30/CAU30; and from 87.0% at 70 cm to 39.5% at 160 cm.

Conclusions: This phantom study demonstrates that the MasterPeace is highly effective and provides relevant radiation protection in addition to existing standard and personal protection equipment. Clinical evaluation in INR procedures is underway.

Purpose: Imaging modalities, particularly magnetic resonance imaging (MRI), have become the gold standard for assessing lesion characteristics of traumatic spinal cord injuries (SCI). Diffusion tensor imaging (DTI), an advanced MRI technique, offers insights into microstructural changes in white matter tracts. While previous studies focused on either acute or chronic SCI, few have examined longitudinal changes during the transition from acute to chronic stages of injury. This study addresses this gap by analyzing the evolution of DTI metrics over the first year following cervical SCI.

Methods: This prospective longitudinal study involved 52 patients with traumatic cervical SCI. MRI and neurological examinations using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) were performed 1 month, 3 months, and 1 year post-injury. Linear mixed model analyses assessed DTI measures over time.

Results: Fractional anisotropy (FA) values gradually decreased in the reference area at the cranio-cervical junction (C0-C4; p < 0.001), indicating ongoing tissue degeneration up to one year after injury, independent of initial clinical severity. FA values at the lesion site correlated moderately with the total motor score 1 month post-SCI (R = 0.37, p = 0.033). Mean diffusivity (MD) increased significantly over time (p < 0.001), suggesting progressive microstructural changes. Axial diffusivity (AD) decreased until 3 months after injury (p < 0.001), then returned to its initial values by 1 year, reflecting dynamic pathophysiological events.

Conclusion: This study highlights the potential of DTI for monitoring microstructural changes after SCI. Longitudinal imaging offers insights into evolving pathology, supports prognostic modeling, and may aid treatment monitoring and outcome prediction.

Background: In patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO) and large ischemic cores, there is a need for reliable imaging biomarkers to predict cerebral edema growth. We investigated the association between severely hypoperfused tissue, measured by time-to-maximum greater than 10 s (Tmax > 10 s) volume, and net water uptake (∆NWU) progression.

Methods: This multicenter retrospective cohort study involved AIS-LVO patients with ASPECTS ≤ 5, undergoing EVT at two comprehensive stroke centers between January 2013 and December 2019. We investigated the relationship between Tmax > 10 s volume derived from perfusion imaging and ∆NWU measured on non-contrast head CT images, hypothesizing that larger Tmax > 10 s volumes are indicative of greater edema growth in large core strokes.

Results: A total of 95 patients (median age, 74 years; 55% women) were included. After adjustment for age, sex, glucose, intravenous thrombolysis, admission NIHSS, ASPECTS, Tan collateral score, last known well-to-CT time, and EVT, higher Tmax > 10 s volume (β, -0.34; P = 0.043) and lower ASPECTS (β, -0.30; P = 0.035) were independently associated with greater ∆NWU.

Conclusion: The study highlights the importance of considering severe pretreatment hypoperfusion, as reflected by larger Tmax > 10 s volumes, in predicting cerebral edema growth in AIS-LVO patients, which could inform clinical strategies, emphasizing the need for larger prospective studies to validate and explore implications.

Purpose: When amyotrophic lateral sclerosis (ALS), a TDP-43 proteinopathy, and progressive supranuclear palsy (PSP), a tauopathy, are associated with frontotemporal dementia (ALS-FTD or PSP-FTD), clinical differentiation can be challenging. There are no established imaging biomarkers to differentiate ALS-FTD from PSP-FTD.

Methods: We evaluated the midsagittal midbrain area (MBA) and the midbrain-to-pons-(MB/P)-ratios in T1 MPRAGE MRI of 36 PSP cases (n = 14 PSP-FTD), 77 ALS cases (n = 10 ALS-FTD), and 72 healthy controls (HC).

Results: In ALS, both parameters were indistinguishable from HC. Patients with ALS-FTD had low MBA-values and MB/P-ratios not significantly different from cases of PSP. While ROC-analyses provided an excellent diagnostic accuracy of both parameters for differentiating PSP from HC (AUC_MBA = 0.974) as well as PSP from ALS (AUC_MBA = 0.982), midbrain morphometry provided poor diagnostic accuracy for distinguishing ALS-FTD from PSP-FTD (AUC_MBA = 0,614).

Conclusion: The MBA and the MB/P-ratio are morphometric parameters that have proven reliable in atypical Parkinsonian syndromes. Both can distinguish between PSP and ALS in their typical clinical forms. However, they cannot differentiate between PSP-FTD and ALS-FTD.