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Purpose: To establish an interleaved multislice variant of the averaged magnetization inversion-recovery acquisitions (AMIRA) approach for 2D spinal cord imaging with increased acquisition efficiency compared with the conventional 2D single-slice approach(es), and to determine essential prerequisites for a working interleaved multislice AMIRA approach in practice., Methods: The general AMIRA concept is based on an inversion recovery-prepared, segmented, and time-limited cine balanced SSFP sequence, generating images of different contrast. For AMIRA imaging of multiple, independent slices in a 2D interleaved fashion, a slice loop within the acquisition loops was programmed. The former non-selective inversions were replaced with slice-selective inversions with user-definable slice thickness., Results: The thickness of the slice-selective inversion in 2D interleaved multislice AMIRA should be doubled compared with the manufacturer's standard setting to avoid an increased sensitivity to flow and pulsation effects particularly in the CSF. However, this solution also limits its practical applicability, as slices located at directly adjacent vertebrae cannot be imaged together. Successful interleaved two-slice AMIRA imaging for a "reference" in vivo protocol with 0.50 × 0.50 mm 2 in-plane resolution and 8-mm slice thickness is demonstrated, therefore halving its acquisition time per slice from 3 min down to 1.5 min., Conclusion: The investigated 2D interleaved two-slice AMIRA variant facilitates spinal cord imaging that maintains similar contrast and the same resolution as the conventional 2D single-slice AMIRA approach, but does so with a halved acquisition time., (© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Background and purpose: In amyotrophic lateral sclerosis (ALS), there is an unmet need for more precise patient characterization through quantitative, ideally operator‐independent, assessments of disease extent and severity. Radially sampled averaged magnetization inversion recovery acquisitions (rAMIRA) magnetic resonance imaging enables gray matter (GM) and white matter (WM) area quantitation in the cervical and thoracic spinal cord (SC) with optimized contrast. We aimed to investigate rAMIRA‐derived SC GM and SC WM areas and their association with clinical phenotype and disability in ALS. Methods: A total of 36 patients with ALS (mean [SD] age 61.7 [12.6] years, 14 women) and 36 healthy, age‐ and sex‐matched controls (HCs; mean [SD] age 63.1 [12.1] years, 14 women) underwent two‐dimensional axial rAMIRA imaging at the inter‐vertebral disc levels C2/3–C5/C6 and the lumbar enlargement level Tmax. ALS Functional Rating Scale–revised (ALSFRS‐R) score, muscle strength, and sniff nasal inspiratory pressure (SNIP) were assessed. Results: Compared to HCs, GM and WM areas were reduced in patients at all cervical levels (p < 0.0001). GM area (p = 0.0001), but not WM area, was reduced at Tmax. Patients with King's Stage 3 showed significant GM atrophy at all levels, while patients with King's Stage 1 showed significant GM atrophy selectively at Tmax. SC GM area was significantly associated with muscle force at corresponding myotomes. GM area at C3/C4 was associated with ALSFRS‐R (p < 0.001) and SNIP (p = 0.0016). Conclusion: Patients with ALS assessed by rAMIRA imaging show significant cervical and thoracic SC GM and SC WM atrophy. SC GM area correlates with muscle strength and clinical disability. GM area reduction at Tmax may be an early disease sign. Longitudinal studies are warranted. [ABSTRACT FROM AUTHOR]

Background: Spinal cord (SC) gray and white matter pathology plays a central role in multiple sclerosis (MS). Objective: We aimed to investigate the extent, pattern, and clinical relevance of SC gray and white matter atrophy in vivo. Methods: 39 relapsing–remitting patients (RRMS), 40 progressive MS patients (PMS), and 24 healthy controls (HC) were imaged at 3T using the averaged magnetization inversion recovery acquisitions sequence. Total and lesional cervical gray and white matter, and posterior (SCPH) and anterior horn (SCAH) areas were automatically quantified. Clinical assessment included the expanded disability status scale, timed 25-foot walk test, nine-hole peg test, and the 12-item MS walking scale. Results: PMS patients had significantly reduced cervical SCAH — but not SCPH — areas compared with HC and RRMS (both p < 0.001). In RRMS and PMS, the cervical SCAH areas increased significantly less in the region of cervical SC enlargement compared with HC (all p < 0.001). This reduction was more pronounced in PMS compared with RRMS (both p < 0.001). In PMS, a lower cervical SCAH area was the most important magnetic resonance imaging (MRI)-variable for higher disability scores. Conclusion: MS patients show clinically relevant cervical SCAH atrophy, which is more pronounced in PMS and at the level of cervical SC enlargement. [ABSTRACT FROM AUTHOR]

Objective: To determine if patients with post‐polio syndrome (PPS) show spinal cord gray matter (SCGM) atrophy and to assess associations between SCGM atrophy, muscle strength and patient‐reported functional decline. Methods: Twenty patients diagnosed with PPS (March of Dimes criteria) and 20 age‐ and sex‐matched healthy controls (HC) underwent 3T axial 2D‐rAMIRA magnetic resonance imaging at the intervertebral disc levels C2/C3–C6/C7, T9/T10 and the lumbar enlargement level (Tmax) (0.5 × 0.5 mm2 in‐plane resolution). SCGM areas were segmented manually by two independent raters. Muscle strength, self‐reported fatigue, depression and pain measures were assessed. Results: Post‐polio syndrome patients showed significantly and preferentially reduced SCGM areas at C2/C3 (p = 0.048), C3/C4 (p = 0.001), C4/C5 (p < 0.001), C5/C6 (p = 0.004) and Tmax (p = 0.041) compared to HC. SCGM areas were significantly associated with muscle strength in corresponding myotomes even after adjustment for fatigue, pain and depression. SCGM areaTmax together with age and sex explained 68% of ankle dorsiflexion strength variance. No associations were found with age at or time since infection. Patients reporting PPS‐related decline in arm function showed significant cervical SCGM atrophy compared to stable patients adjusted for initial disease severity. Conclusions: Patients with PPS show significant SCGM atrophy that correlates with muscle strength and is associated with PPS‐related functional decline. Our findings suggest a secondary neurodegenerative process underlying SCGM atrophy in PPS that is not explained by aging or residua of the initial infection alone. Confirmation by longitudinal studies is needed. The described imaging methodology is promising for developing novel imaging surrogates for SCGM diseases. [ABSTRACT FROM AUTHOR]

Background: MR imaging of the spinal cord (SC) gray matter (GM) at the cervical and lumbar enlargements' level may be particularly informative in lower motor neuron disorders, e. g., spinal muscular atrophy, but also in other neurodegenerative or autoimmune diseases affecting the SC. Radially sampled averaged magnetization inversion recovery acquisition (rAMIRA) is a novel approach to perform SC imaging in clinical settings with favorable contrast and is well-suited for SC GM quantitation. However, before applying rAMIRA in clinical studies, it is important to understand (i) the sources of inter-subject variability of total SC cross-sectional areas (TCA) and GM area (GMA) measurements in healthy subjects and (ii) their relation to age and sex to facilitate the detection of pathology-associated changes. In this study, we aimed to develop normalization strategies for rAMIRA-derived SC metrics using skull and spine-based metrics to reduce anatomical variability. Methods: Sixty-one healthy subjects (age range 11–93 years, 37.7% women) were investigated with axial two-dimensional rAMIRA imaging at 3T MRI. Cervical and thoracic levels including the level of the cervical (C4/C5) and lumbar enlargements (Tmax) were examined. SC T2-weighted sagittal images and high-resolution 3D whole-brain T1-weighted images were acquired. TCA and GMAs were quantified. Anatomical variables with associations of | r | > 0.30 in univariate association with SC areas, and age and sex were used to construct normalization models using backward selection with TCAC4/C5 as outcome. The effect of the normalization was assessed by % relative standard deviation (RSD) reductions. Results: Mean inter-individual variability and the SD of the SC area metrics were considerable: TCAC4/5: 8.1%/9.0; TCATmax: 8.9%/6.5; GMAC4/C5: 8.6%/2.2; GMATmax: 12.2%/3.8. Normalization based on sex, brain WM volume, and spinal canal area resulted in RSD reductions of 23.7% for TCAs and 12.0% for GM areas at C4/C5. Normalizations based on the area of spinal canal alone resulted in RSD reductions of 10.2% for TCAs and 9.6% for GM areas at C4/C5, respectively. Discussion: Anatomic inter-individual variability of SC areas is substantial. This study identified effective normalization models for inter-subject variability reduction in TCA and SC GMA in healthy subjects based on rAMIRA imaging. [ABSTRACT FROM AUTHOR]

• The cervical spinal cord compartments of 65 MS patients and 20 healthy controls were assessed longitudinally over 1.10±0.28 years on MRI using the novel averaged magnetization inversion recovery acquisitions sequence and in-house developed post-processing methods. • Patients with clinical progression showed faster reduction of total spinal cord areas and spinal cord white matter areas over time at the level of cSC enlargement. • MS patients with clinical disease progression demonstrate subtle signs of a more pronounced tissue loss at the level of cSC enlargement. Although cervical spinal cord (cSC) area is an established biomarker in MS, there is currently a lack of longitudinal assessments of cSC gray and white matter areas. We conducted an explorative analysis of longitudinal changes of cSC gray and white matter areas in MS patients. 65 MS patients (33 relapsing-remitting; 20 secondary progressive and 12 primary progressive) and 20 healthy controls (HC) received clinical and upper cSC MRI assessments over 1.10±0.28 years. cSC compartments were quantified on MRI using the novel averaged magnetization inversion recovery acquisitions sequence (in-plane resolution=0.67 × 0.67mm2), and in-house developed post-processing methods. Patients were stratified regarding clinical progression. Patients with clinical progression showed faster reduction of cSC areas over time at the level of cSC enlargement (approximate vertebral level C4-C5) compared to stable patients (p <0.05). In addition, when compared to the rostral-cSC (approximate vertebral level C2-C3), a preferential reduction of cSC and white matter areas over time at the level of cSC enlargement (p <0.05 and p <0.01, respectively) was demonstrated only in patients with clinical progression, but not in stable MS patients and HC. Compared to HC, MS patients showed comparable changes over time in all cSC compartments. MS patients with clinical disease progression demonstrate subtle signs of a more pronounced tissue loss at the level of cSC enlargement. Future studies should consider larger sample sizes and more extended observation periods. [ABSTRACT FROM AUTHOR]

• Utilization of a motion-insensitive radial acquisition for spinal cord MRI. • First morphometric MRI approach with a particular focus on the thoracic spinal cord. • Contrast adaptation based on averaged magnetization inversion recovery acquisitions. • Strong contrast between gray and white matter allows quantitative volumetry. • Proof-of-concept for spinal muscular atrophy and post-polio syndrome. Spinal cord (SC) gray and white matter atrophy quantification by advanced morphometric MRI can help to better characterize the course of neurodegenerative diseases in vivo, such as e.g. lower motor neuron disorders. Imaging the lower thoracic cord - containing those motor neurons that control leg function - could be particularly informative, however, is challenging due to tissue composition, physiological motion and large field of views. An "averaged magnetization inversion recovery acquisitions" (AMIRA) approach with a radial k-space acquisition scheme was developed. The method is designed for morphometric SC imaging with a focus on the thoracic SC. In a typical setting, radial AMIRA acquires transverse slices with a high 0.50 × 0.50mm2 in-plane resolution and a pronounced positive contrast between thoracic gray and white matter, within typically 2:39 min. Additional proof-of-concept measurements in patients demonstrate that such contrast and resolving capability is indeed necessary to assess potential atrophy of the anterior horns. Radial AMIRA utilizes two benefits of radial MRI techniques: being generally less prone to motion effects and that fold over artifacts can manifest less intrusively. These benefits are united with the original AMIRA approach which allows the contrast to be 'tuned' and improved based on the combination of five simultaneously acquired images of different tissue contrast. Radial AMIRA is a promising approach for in vivo SC gray and white matter atrophy visualization and quantification in lower motor neuron diseases and other autoimmune or genetic diseases involving the entire (not only cervical) spinal cord. [ABSTRACT FROM AUTHOR]