PURPOSE:To develop a sequence for the rapid acquisition of MR elastography (MRE) parameters in 3D, with simultaneous measurement of proton-density fat fraction (PDFF) and R2* for multiparametric assessment of liver disease. METHODS:The proposed sequence uses an interleaved motion-encoding scheme to acquire 3D volumes of all motion encodings and wave offsets from a single series of readouts with constant repetition time. This leads to a highly time-efficient acquisition, which together with incoherent k-space undersampling permits all MRE data to be acquired in a single breathhold. The undersampled volumes are reconstructed using compressed sensing with model-based temporal regularisation. The sequence can be combined with a multi-echo readout to allow 3D PDFF and R2* maps to be reconstructed from the reference volume of the MRE acquisition. Validation was performed in phantoms and in eight healthy volunteers. RESULTS:Phantom measurements of all viscoelastic parameters, PDFF, and R2* corresponded closely with reference measurements. Average liver tissue parameter values acquired with the combined MRE, PDFF and R2* sequence at 3 T were 1.36 ± 0.15 m/s for shear-wave speed, 1.78 ± 0.41 kPa for the magnitude of the complex shear modulus, 0.70 ± 0.16 kPa for the loss modulus, 3.6% ± 1.0% for PDFF, and 46.9 ± 7.3 s-1 for R2*. CONCLUSION:Single-breathhold 3D MRE in the liver was achieved with a novel acquisition ordering. The sequence offers 3D elastograms from a 16-s breathhold, or 3D elastograms with co-registered PDFF and R2* maps from a 21-s breathhold.

BACKGROUND:Non-contrast T1-weighted cardiovascular MR (CMR) enables assessment of coronary atherosclerotic plaques by exploiting elevated signal intensity within high-risk plaque components. The novel iT2prep-BOOST sequence provides co-registered coronary lumen and vessel wall whole-heart imaging, potentially facilitating plaque assessment. However, direct comparison of quantitative plaque measures between iT2prep-BOOST and coronary computed tomography angiography (CCTA), the non-invasive standard for plaque assessment, remains limited. This study aimed to compare coronary plaque burden and plaque signal intensity measured by iT2prep-BOOST with plaque burden and plaque attenuation characteristics derived from CCTA. METHODS:In this prospective, observational study, patients with stable coronary artery disease confirmed by diagnostic CCTA were recruited and subsequently underwent CMR using the iT2prep-BOOST sequence. Using semi-automated software, per-lesion cross-sectional areas of total, calcified, non-calcified, and low-density non-calcified plaque (≤30 Hounsfield unit) together with measures of plaque burden (percentage vessel atheroma) were quantified on CCTA. The corresponding coronary atherosclerotic lesion was analysed on T1-weighted black-blood iT2prep-BOOST CMR to assess cross-sectional plaque area, burden, and plaque-to-myocardial signal intensity ratio (PMR). RESULTS:A total of 188 lesions in 85 patients were analysed and compared between iT2prep-BOOST and CCTA. Plaque burden estimates derived from iT2prep-BOOST demonstrated moderate correlation with CCTA-derived total plaque burden (r = 0.58) and non-calcified plaque burden (r = 0.54). However, agreement between modalities was limited. For total plaque burden, the mean difference was -4% (95% CI: -7% to -2%) with limits of agreement ranging from -38% to 29%. For non-calcified plaque burden, the mean difference was 3% (95% CI: 0% to 5%) with limits of agreement from -34% to 39%. In univariate regression analyses, PMR was associated with increasing total, non-calcified, and low-density non-calcified plaque areas and decreasing CT attenuation values. CONCLUSION:Coronary plaque burden assessed by iT2prep-BOOST demonstrated modest correlation and limited agreement with CCTA-derived plaque burden, indicating that the two modalities are not directly interchangeable for plaque burden quantification. Nevertheless, the observed associations between PMR and adverse CCTA plaque characteristics support the potential role of T1-weighted CMR as a complementary, non-invasive tool for coronary plaque characterization.

Aims:Left atrial (LA) myopathy is a key driver of atrial fibrillation (AF) development and progression. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance enables non-invasive quantification of LA fibrosis, a hallmark of atrial myopathy. However, conventional LGE sequences lack sufficient spatial resolution to accurately depict the thin atrial wall, and reference data in healthy cohorts are scarce. This study aimed to evaluate a high-resolution isotropic 3D LGE Dixon sequence for assessing LA fibrosis in healthy controls and AF patients. Methods and results:In this prospective study, 40 ablation-naïve AF patients (21 paroxysmal, 19 persistent) and 20 healthy controls underwent isotropic (1.3 mm3) 3D whole-heart LGE imaging. Segmentation was successfully performed using CemrgApp in all participants. A setup-specific threshold for fibrosis detection was defined as an image-intensity ratio (IIR) > 1.34 (mean + 2SD of healthy controls) and validated against pre-procedural electroanatomical mapping (EAM) and follow-up imaging at six months post ablation. At baseline, total LA enhancement was higher in persistent than paroxysmal AF (3.65% [1.84-7.16] vs. 1.16% [0.43-2.27]; P = 0.044) and controls (1.25% [0.65-1.75]; P = 0.041). No significant correlation was observed between total LGE-derived fibrosis and bipolar low-voltage area (ρ = -0.03, P = 0.87), though point-by-point analysis showed a weak negative correlation (ρ = -0.05, P < 0.001). In patients with sinus rhythm at follow-up, total fibrosis increased from 1.68% [0.64-6.51] to 6.30% [2.53-12.28]; P < 0.001, driven by peri-ablational scar formation, with no change in remote myocardium. Intra-reader correlation for LA-LGE was excellent: ICC 0.99 (95% CI 0.95-0.99). Conclusion:High resolution isotropic 3D LA-LGE enables robust detection of ablation-induced scarring and biologically plausible fibrosis differences between AF stages. However, its correlation with bipolar voltage mapping remains limited, suggesting that LGE and EAM provide complementary information on atrial myopathy.

BACKGROUND:Coronary computed tomographic angiography (CCTA) is a first-line test for anatomical evaluation of the coronary arteries in stable chest pain. Despite technical advances, CCTA requires breath hold and exposes patients to ionizing radiation and contrast agents. Coronary cardiovascular magnetic resonance angiography (CCMRA) has been limited by long and unpredictable scan times, lower spatial resolution, and restricted plaque characterization. We developed a novel cardiovascular magnetic resonance sequence, Bright-blood and black-blood phase SensiTive (BOOST) sequence, which produces a co-registered bright-blood image for lumen visualization and a T1-weighted black-blood image for vessel wall and plaque assessment from a single scan with predictable scan times. OBJECTIVES:To compare the BOOST-CCMRA sequence with CCTA for plaque characterization and stenosis evaluation in patients with stable chest pain. METHODS:Sixty consecutive patients (mean age 56 years, 60% (36/60) male) with stable chest pain were prospectively enrolled. All underwent CCTA followed by BOOST-CCMRA on a 1.5T magnetic resonance imaging scanner. Coronary plaques identified on CCTA were analyzed on the black-blood BOOST image using the signal from plaque to derive the plaque-to-myocardium ratio (PMR); a healthy vessel-to-myocardium ratio (HVMR) was derived as reference. Plaque morphology was assessed by CCTA appearance. Luminal stenosis was assessed on BOOST bright-blood images and compared with CCTA. RESULTS:Of 60 patients, 35 had plaque on CCTA, with 72 plaques identified. 9 plaques were not detected on BOOST, giving an 88% (63/72) detection success. BOOST showed agreement with CCTA in stenosis grading for 51 of 63 lesions (81%): 23/26 (88%) minimal, 20/24 (83%) mild, 4/7 (57%) moderate, 3/5 (60%) severe, and 1/1 (100%) occlusion. PMR was significantly higher than HVMR (0.64 ± 0.16 vs 0.36 ± 0.11; p < 0.001) across all plaque subtypes (calcified 0.53 ± 0.11, partially calcified 0.70 ± 0.15, non-calcified 0.69 ± 0.16, all p < 0.001 vs HVMR). Hypertension and family history of premature cardiovascular disease were associated with higher PMR values. CONCLUSION:The BOOST sequence allows simultaneous evaluation of coronary lumen and plaque characteristics in a single non-contrast CCMRA acquisition, with reliable plaque identification and good agreement with CCTA for stenosis severity assessment. This approach may offer free-breathing alternative, without radiation or contrast, for integrated anatomical and plaque imaging in patients with stable chest pain.

OBJECTIVES:To propose and validate a simplified method for 3D simultaneous post-contrast parametric mapping and synthetic late gadolinium enhancement (LGE) imaging at 0.55T for comprehensive whole-heart myocardial tissue characterization. MATERIALS AND METHODS:A 3D joint T1/T2 mapping research sequence is adopted from a previous study. Three interleaved volumes with inversion recovery (IR) preparation, no magnetization preparation, and T2 preparation were acquired with image navigators to enable 100% respiratory scan efficiency. Intrinsically co-registered 3D T1, T2, and proton density maps were calculated using a dictionary-matching method, and Bloch equation-based IR and T2 preparation-IR (T2IR) signal models were proposed to generate multi-contrast 3D synthetic LGE images. In vivo evaluation included 10 data sets from a porcine myocardial infarction model to validate the performance of the proposed 3D method in comparison with that of separately scanned 2D reference sequences including post-contrast T1 mapping, pre-contrast T2 mapping, and LGE. RESULTS:For the 10 swine data sets, 2D and 3D T1/T2 maps had consistent findings regarding the changes in T1/T2 values of myocardial infarction, presenting significantly decreased post-contrast T1 (2D: 279±48 vs. 472±44 ms, P <0.01; 3D: 355±32 vs. 597±48 ms, P <0.01) and increased T2 (2D: 102.4±11.5 vs. 66.4±3.1 ms, P <0.01; 3D: 71.0±5.3 vs. 39.4±4.5 ms, P <0.01) in scar compared with remote myocardium. 3D multi-contrast LGE images were successfully generated without additional scan and provided excellent image contrasts. Compared with 2D LGE, 3D synthetic bright-blood IR-LGE had improved scar-to-myocardium contrast ( P <0.01) with comparable image contrasts of scar-to-blood ( P =0.08) and blood-to-myocardium ( P =0.71), synthetic gray-blood IR-LGE had improved scar-to-blood and scar-to-myocardium contrast ( P <0.01) with comparable blood-to-myocardium contrast ( P =0.06), whereas synthetic dark-blood T2IR-LGE demonstrated significant differences regarding all tissue contrasts ( P <0.01). CONCLUSIONS:The proposed method provided imaging findings consistent with 2D references and shows promise for comprehensive myocardial tissue characterization in a single simple scan.

Low-field MRI has recently gained interest due to its potential for increased accessibility, reduced cost, and improved safety. However, high-quality anatomical imaging and robust tissue characterization remains an active area of research, particularly when aiming for a simple, one-click scan that captures all relevant information in a single acquisition. Bright-blood imaging is widely used for visualizing cardiac structures and coronary arteries, whereas black-blood is optimal for delineating the myocardium, atrial and vessel walls. High-resolution imaging is required for the accurate detection and segmentation of small anatomical structures, such as the coronary arteries, to enable assessment of narrowing or blockages. Co-registered T 1 / T 2 $$ {T}_1/{T}_2 $$ mapping enables quantitative myocardial tissue characterization, offering valuable clinical information for the detection of myocardial abnormalities. In this study, we sought to develop a novel free-breathing, motion-compensated 3D multi-contrast high-resolution cardiac MR sequence for simultaneous assessment of whole-heart cardiovascular anatomy via bright- and black-blood imaging and myocardial tissue quantification by joint T 1 $$ {T}_1 $$ and T 2 $$ {T}_2 $$ mapping at 0.55 T in a single scan. Data were acquired over six interleaved contrasts with various preparation modules using a variable flip angle bSSFP spiral-like readout with 2D image-based navigation for translational motion correction, resulting in a predictable acquisition time of ≈ 12 $$ \approx 12 $$ min. Images were reconstructed using non-rigid motion corrected iterative sensitivity encoding followed by high-dimensional patch-based low-rank denoising, resulting in the acquisition, reconstruction and quantitative mapping time of ≈ 31 $$ \approx 31 $$ min. In the phantom study, sequence performance was evaluated using correlation and Bland-Altman analysis against reference gold-standard and clinical mapping methods. In vivo, 3D bright- and black-blood volumes were assessed in multiple views, and vessel sharpness was quantified from multiplanar images. For joint T 1 / T 2 $$ {T}_1/{T}_2 $$ mapping, bull's-eye plots were generated to evaluate the mean, standard deviation, and coefficient of variation for apical, mid-cavity, and basal segments, and results were summarized using violin plots. Differences between the proposed 3D sequence and established 2D methods were analyzed with a two-tailed t $$ t $$ -test. In the phantom study, a small positive bias in T 1 $$ {T}_1 $$ of 6 . 3 ms $$ 6.3\kern0.3em \mathrm{ms} $$ was observed compared with inversion recovery spin-echo and 23 . 5 ms $$ 23.5\kern0.3em \mathrm{ms} $$ with MOLLI, while for T 2 $$ {T}_2 $$ biases of 7 . 3 ms $$ 7.3\kern0.3em \mathrm{ms} $$ compared with spin-echo and 0 . 8 ms $$ 0.8\kern0.3em \mathrm{ms} $$ with T 2 $$ {T}_2 $$ prep bSSFP were found. In vivo, statistically similar T 1 $$ {T}_1 $$ values of ( 648 ± 26 ) ms $$ \left(648\pm 26\right)\kern0.3em \mathrm{ms} $$ and T 2 $$ {T}_2 $$ values of ( 56 . 9 ± 3 . 2 ) ms $$ \left(56.9\pm 3.2\right)\kern0.3em \mathrm{ms} $$ were obtained, with differences versus MOLLI of - 3 ms ± 15 ms $$ -3\kern0.3em \mathrm{ms}\pm 15\kern0.3em \mathrm{ms} $$ ( p = 0 . 75 $$ p=0.75 $$ ) and versus T 2 $$ {T}_2 $$ prep bSSFP of - 0 . 5 ms ± 2 . 1 ms $$ -0.5\kern0.3em \mathrm{ms}\pm 2.1\kern0.3em \mathrm{ms} $$ ( p = 0 . 63 $$ p=0.63 $$ ). The proposed sequence demonstrated high image quality and accurate mapping despite the inherent limitations of low-field strength, suggesting its feasibility for comprehensive cardiac assessment in resource-limited environments.

Aims:Automated image acquisition in combination with a 2D image navigator allows for an improved spatial resolution of coronary magnetic resonance angiography (CMRA) that is approaching that of coronary computed tomography angiography. However, it remains unclear whether this increased spatial resolution significantly improves the diagnostic performance of CMRA in detecting the severity of coronary artery disease (CAD). Objectives:To compare 0.7 mm3 CMRA to 0.9 mm3 CMRA for the detection of CAD, using two-dimensional quantitative coronary angiography as the reference standard. Methods and results:A total of 81 patients were recruited to the study. The diagnostic performance of 0.7 mm3 and 0.9 mm3 CMRA to detect ≥50% coronary stenosis was compared on a per-patient and per-vessel basis. On a per-patient basis, the sensitivity of 0.7 mm3 CMRA was significantly better than 0.9 mm3 CMRA to detect ≥50% stenosis (0.885 vs. 0.721, P = 0.01), whilst the negative predictive value showed no difference (0.500 vs. 0.320, P = 0.10). On a per vessel basis, the sensitivity (0.716 vs. 0.558, P ≤ <0.01), negative predictive value (0.857 vs. 0.802, P = 0.01), and area under the curve (0.742 vs. 0.682, P = 0.04) were significantly better for 0.7 mm3 CMRA to detect ≥50% stenosis. Conclusion:CMRA with an improved spatial resolution of 0.7 mm3 compared to 0.9 mm3 was superior for the detection of ≥50% stenosis.

ABSTRACT Low‐field MRI has recently gained interest due to its potential for increased accessibility, reduced cost, and improved safety. However, high‐quality anatomical imaging and robust tissue characterization remains an active area of research, particularly when aiming for a simple, one‐click scan that captures all relevant information in a single acquisition. Bright‐blood imaging is widely used for visualizing cardiac structures and coronary arteries, whereas black‐blood is optimal for delineating the myocardium, atrial and vessel walls. High‐resolution imaging is required for the accurate detection and segmentation of small anatomical structures, such as the coronary arteries, to enable assessment of narrowing or blockages. Co‐registered mapping enables quantitative myocardial tissue characterization, offering valuable clinical information for the detection of myocardial abnormalities. In this study, we sought to develop a novel free‐breathing, motion‐compensated 3D multi‐contrast high‐resolution cardiac MR sequence for simultaneous assessment of whole‐heart cardiovascular anatomy via bright‐ and black‐blood imaging and myocardial tissue quantification by joint and mapping at 0.55 T in a single scan. Data were acquired over six interleaved contrasts with various preparation modules using a variable flip angle bSSFP spiral‐like readout with 2D image‐based navigation for translational motion correction, resulting in a predictable acquisition time of min. Images were reconstructed using non‐rigid motion corrected iterative sensitivity encoding followed by high‐dimensional patch‐based low‐rank denoising, resulting in the acquisition, reconstruction and quantitative mapping time of min. In the phantom study, sequence performance was evaluated using correlation and Bland‐Altman analysis against reference gold‐standard and clinical mapping methods. In vivo, 3D bright‐ and black‐blood volumes were assessed in multiple views, and vessel sharpness was quantified from multiplanar images. For joint mapping, bull's‐eye plots were generated to evaluate the mean, standard deviation, and coefficient of variation for apical, mid‐cavity, and basal segments, and results were summarized using violin plots. Differences between the proposed 3D sequence and established 2D methods were analyzed with a two‐tailed ‐test. In the phantom study, a small positive bias in of was observed compared with inversion recovery spin‐echo and with MOLLI, while for biases of compared with spin‐echo and with prep bSSFP were found. In vivo, statistically similar values of and values of were obtained, with differences versus MOLLI of () and versus prep bSSFP of (). The proposed sequence demonstrated high image quality and accurate mapping despite the inherent limitations of low‐field strength, suggesting its feasibility for comprehensive cardiac assessment in resource‐limited environments.

Quantitative MRI (T1-T2) has been shown to be useful for early diagnosis of osteoarthritis (OA) in the knee at 1.5 and 3 T. However, limited research has been performed at 0.55 T. In this study, we aim to develop and evaluate the feasibility of a 3D joint T1-T2 mapping estimation and synthetic contrasts radial sequence for quantitative and anatomical water-fat imaging of the knee at 0.55 T. The proposed sequence consists of a free-running, 3D-golden angle radial trajectory preceded with inversion recovery and T 2 $$ {T}_2 $$ -preparation pulses. Reconstruction of images is performed with parallel imaging and high-dimensional low-rank patch-based regularization. A water-fat separation technique is employed to obtain water and fat images, and T1-T2 maps can be obtained for water and the echo images via Bloch-equation dictionary matching. The sequence was validated on a standardized phantom and in 16 healthy subjects. Phantom results are in good agreement with SE references, with biases of 1.78 $$ 1.78 $$  ms for T 1 $$ {T}_1 $$ and - 0.23 $$ -0.23 $$ ms for T 2 $$ {T}_2 $$ . In vivo, the average mean in the articular cartilage was T 1 = 460 ± 45 $$ {T}_1=460\pm 45 $$ ms and T 2 = 33 ± 4 $$ {T}_2=33\pm 4 $$ ms, compared to T 1 = 394 ± 57 $$ {T}_1=394\pm 57 $$ ms, T 2 = 44 ± 10 $$ {T}_2=44\pm 10 $$ ms for the reference sequences. Synthetic contrast images produced with the sequence are comparable to the references in terms of contrast to noise ratio (CNR) and relative contrast metrics. The feasibility of 3D joint T1-T2 mapping of the knee at 0.55 T in a single scan of ~3 min was demonstrated, showing promising results for efficient knee imaging. Studies in a larger cohort of patients with osteoarthritis at 0.55 T are now warranted.

BACKGROUND:Centerline semi-automatic measurements (CSAM) of the thoracic aorta have been shown to reduce interobserver variability of diameter measurements. The purpose of this study is to demonstrate the feasibility and efficiency of non-expert CSAM using contrast-enhanced magnetic resonance angiography (CE-MRA) versus double oblique (DO) multiplanar reformation (MPR) measurements obtained by experts, and to assess CSAM failure rate in subjects with and without thoracic aortic disease (TAD). METHODS:Image-based navigator (iNAV) and variable density sampling with Cartesian spiral-like trajectories (VD-CASPR) framework for non-rigid motion correction and image acceleration were utilized for inversion recovery gradient echo MRA. Thoracic MRA was obtained in 41 TAD subjects and 27 normals and independently analyzed by expert cardiologists for DO MPR measurements; one cardiovascular imaging fellow (CSAM1) obtained CSAM in all subjects; another (CSAM2) obtained CSAM in TAD patients. Nine prior MRA exams were analyzed for CSAM in seven subjects with stable aneurysms. Post-processing efficiency and intra/interobserver agreement were assessed at the sinus of Valsalva (SOV), sinotubular junction (STJ), and ascending aorta (AAO) using intra/interclass correlation coefficients. Contour failures were graded on a four-point scale: 1- failure of ≤25% vessel circumference; 2- 26-50% circumference failure; 3- 51-75% circumference failure; 4- >75% failure. RESULTS:CSAM1 failure rate was 13% and 14% in the TAD and normal cohorts, respectively (p = 0.78). CSAM 2 failure rate was 2% in the TAD cohort. Intraobserver agreement was excellent for both methods. SOV interobserver agreement with DO MPR performed the worst, with the lowest interclass correlation (ICC) for SOV major (vs physician 1) in the normal cohort (ICC = .69). Otherwise, agreement with DO MPR was near excellent. Major diameter interobserver agreement was excellent in the TAD cohort. Efficiency was highest for CSAM2. In stable TAD, baseline and follow-up major diameter measurements were not significantly different. CONCLUSION:Non-expert MRA CSAM is feasible with excellent intraobserver and excellent to near excellent interobserver agreement at the STJ and AAO levels compared to expert DO MPR. CSAM failure rates varied significantly between non-expert readers; inter-study CSAM were overall precise.

Objectives: To propose and validate a simplified method for 3D simultaneous post-contrast parametric mapping and synthetic late gadolinium enhancement (LGE) imaging at 0.55T for comprehensive whole-heart myocardial tissue characterization. Materials and Methods: A 3D joint T1/T2 mapping research sequence is adopted from a previous study. Three interleaved volumes with inversion recovery (IR) preparation, no magnetization preparation, and T2 preparation were acquired with image navigators to enable 100% respiratory scan efficiency. Intrinsically co-registered 3D T1, T2, and proton density maps were calculated using a dictionary-matching method, and Bloch equation-based IR and T2 preparation-IR (T2IR) signal models were proposed to generate multi-contrast 3D synthetic LGE images. In vivo evaluation included 10 data sets from a porcine myocardial infarction model to validate the performance of the proposed 3D method in comparison with that of separately scanned 2D reference sequences including post-contrast T1 mapping, pre-contrast T2 mapping, and LGE. Results: For the 10 swine data sets, 2D and 3D T1/T2 maps had consistent findings regarding the changes in T1/T2 values of myocardial infarction, presenting significantly decreased post-contrast T1 (2D: 279±48 vs. 472±44 ms, P <0.01; 3D: 355±32 vs. 597±48 ms, P <0.01) and increased T2 (2D: 102.4±11.5 vs. 66.4±3.1 ms, P <0.01; 3D: 71.0±5.3 vs. 39.4±4.5 ms, P <0.01) in scar compared with remote myocardium. 3D multi-contrast LGE images were successfully generated without additional scan and provided excellent image contrasts. Compared with 2D LGE, 3D synthetic bright-blood IR-LGE had improved scar-to-myocardium contrast ( P <0.01) with comparable image contrasts of scar-to-blood ( P =0.08) and blood-to-myocardium ( P =0.71), synthetic gray-blood IR-LGE had improved scar-to-blood and scar-to-myocardium contrast ( P <0.01) with comparable blood-to-myocardium contrast ( P =0.06), whereas synthetic dark-blood T2IR-LGE demonstrated significant differences regarding all tissue contrasts ( P <0.01). Conclusions: The proposed method provided imaging findings consistent with 2D references and shows promise for comprehensive myocardial tissue characterization in a single simple scan.

Abdominal aortic aneurysms (AAAs) are characterized by progressive extracellular matrix (ECM) degradation and inflammation of the aortic wall. 2-Hydroxypropyl-β-cyclodextrin (cyclodextrin) has shown potential in attenuating AAA progression via activation of transcription factor EB. This study evaluated whether molecular magnetic resonance imaging (MRI) enables non-invasive monitoring of therapeutic effects in a murine AAA model. Thirty-two male apolipoprotein-E knockout mice with angiotensin II-induced AAAs received either cyclodextrin (n = 8) or saline (n = 10) for three weeks. A dual molecular MRI approach was applied using a gadolinium-based elastin-specific probe to assess ECM integrity and ultrasmall superparamagnetic iron oxide particles (USPIO, iron oxide particles) to evaluate macrophage-driven inflammation. MRI was performed at pre-treatment baseline and at 2 and 3 weeks after treatment initiation. Cyclodextrin-treated animals demonstrated significantly smaller aortic cross-sectional areas (2.31 ± 0.36 mm² vs. 2.96 ± 0.62 mm²; p = 0.018) and lower elastin-specific signal enhancement (1.56 ± 0.26 vs. 2.15 ± 0.69; p = 0.038), indicating preserved ECM integrity. In contrast, no significant differences in iron oxide particles-related signal changes were observed between groups (p = 0.441), consistent with histological and molecular findings. This study shows that elastin-specific molecular imaging non-invasively monitors cyclodextrin's effects in AAA, whereas iron oxide particle imaging revealed no significant in vivo signal changes, consistent with ex vivo findings and indicating limited detectable inflammatory modulation associated with cyclodextrin treatment under the conditions of this study.

Background:Serial assessment of the thoracic aorta with magnetic resonance angiography (MRA) is desirable due to 3D volumetric dataset, high spatial resolution, and lack of ionizing radiation. Electrocardiogram (ECG) gated, contrast-enhanced (CE), inversion recovery gradient echo MRA is efficient and historically provides low artifact burden, but the window for imaging with weak albumin binding extracellular gadolinium based contrast agents is small. Our purpose was to acquire whole-chest gated CE-MRA with 1.2 mm3 resolution using image-based navigator (iNAV) for motion correction/contrast monitoring, and variable density sampling in 4-5 min. Image quality and vessel diameter reproducibility are assessed against time resolved MRA (TR-MRA). Methods:iNAV CE-MRA and TR-MRA were obtained prospectively in 40 patients and reviewed by 3 blinded cardiologists for vessel diameter and image quality rated on a four point scale: (1) non-diagnostic; (2) poor-significant blurring; (3) good-mild blurring; and (4) excellent. Reproducibility and image quality were evaluated using the concordance correlation statistic and Cohen's kappa with mean differences evaluated using paired t-tests and repeat-measures ANOVA. Results:iNAV CE-MRA scan time was 4.2 ± 0.7 min. iNAV CE-MRA quality score was higher (p < .001); average difference was 1.4 ± .08 at the sinus of Valsalva (SOV), 1.3 ± .08 at the sinotubular junction (STJ), and .87 ± .10 at the ascending aorta (AAO). Major/minor diameter interobserver agreement was better for iNAV CE-MRA (SOV ICC = .87-.93; STJ ICC = .95-.96; AAO ICC = .96-.97) vs. TR-MRA (SOV ICC = .69-.82; STJ ICC = .78-.83; AAO ICC = .89), as was intraobserver agreement (SOV ICC = .93-.95; STJ ICC = .94-.96; AAO ICC = .96-.97) vs. TR-MRA (SOV ICC = .81-.88; STJ ICC = .72-.73; AAO ICC = .87-.93). Conclusion:iNAV CE-MRA is feasible within a clinically reasonable scan time, provides superior image quality, and measurement reproducibility vs. TR-MRA.

Motivation: Cardiac cine MRF is a powerful quantitative imaging technique that enables comprehensive tissue characterization and left ventricular functional assessment in a single-scan. However, it has not been demonstrated at 0.55T. Goal(s): To investigate the feasibility of a bSSFP free-running cardiac-MRF sequence at 0.55T for simultaneous T1/T2 and cine-imaging in a single breath-hold-scan of ~13s. Approach: The sequence, implemented in Pulseq, uses continuous tiny-golden-angle radial bSSFP readouts with IR-T2-prep modules. Phantom results were compared against IR-SE references and in-vivo results against previously reported literature values. Results: T1/T2-maps show good agreement with phantom reference and in-vivo results show good image quality for T1/T2-maps and cine-images. Impact: A simultaneous acquisition of T1 and T2 maps, along with cine imaging at 0.55T in a single ~13s scan could provide a more affordable and accessible approach to assess cardiovascular disease.