BACKGROUND: Excessive daytime sleepiness (EDS) substantially impairs health-related quality of life and cognitive function in obstructive sleep apnea (OSA) patients. However, the underlying neuropathological mechanisms r...BACKGROUND: Excessive daytime sleepiness (EDS) substantially impairs health-related quality of life and cognitive function in obstructive sleep apnea (OSA) patients. However, the underlying neuropathological mechanisms remain poorly understood. PURPOSE: To investigate the associations between EDS, cognitive deficits, and brain alterations in OSA patients. STUDY TYPE: Prospective. POPULATION: One hundred two OSA patients (16 female, median age (IQR) 33.00 [28.00-41.00]) and 86 healthy controls (HCs) (16 female, median age (IQR) 33.00 [25.00-50.25]) were prospectively recruited. FIELD STRENGTH/SEQUENCE: 3 T, 3D spoiled gradient-echo, diffusion-weighted spin-echo, blood oxygen level-dependent gradient-echo planar. ASSESSMENT: The Epworth Sleepiness Scale, multiparameter MRI, and a series of neuropsychological tests (the number connection tests A and B, digit symbol test, line tracing test, serial dotting test, and Stroop Color/Word test) were performed to evaluate EDS, brain alterations, and cognitive performances. STATISTICAL TESTS: Mann-Whitney U test, independent samples t-test, chi-square test, Spearman's correlation, and mediation analyses were used. Significance level: p < 0.05. RESULT: OSA patients exhibited statistically poorer cognitive performance (effect size = 0.23-0.37), lower diffusion tensor imaging along the perivascular space (DTI-ALPS) index (effect size = 0.25), and abnormal network topology (effect size = -0.80 to 0.57) compared with HCs. EDS significantly correlated with poorer cognitive performance (r = -0.173 to 0.258), lower DTI-ALPS index (r = -0.199), and abnormal network topology (r = -0.364 to 0.279) in all participants. Furthermore, aberrant degree centrality and nodal efficiency in the bilateral middle frontal gyrus (MFG) and left inferior parietal lobule (IPL) may mediate the relationship between EDS and cognitive deficits (indirect effect = -0.13 to 0.36). DATA CONCLUSION: These results demonstrate that cognition, DTI-ALPS index, and network topology were all compromised in OSA. Furthermore, abnormal network topology in the bilateral MFG and left IPL may mediate the relationship between EDS and cognitive deficits. EVIDENCE LEVEL: Level 2. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Cerebral small vessel disease (CSVD) is an important risk factor for stroke and cognitive impairment, adversely affecting long-term outcomes. Methylglyoxal (MGO), a by-product of glycolysis, is implicated in...BACKGROUND: Cerebral small vessel disease (CSVD) is an important risk factor for stroke and cognitive impairment, adversely affecting long-term outcomes. Methylglyoxal (MGO), a by-product of glycolysis, is implicated in various vascular complications. PURPOSE: To explore the correlation between MGO and CSVD, particularly with white matter hyperintensities (WMH). STUDY TYPE: Prospective. POPULATION: One hundred and fifteen patients with first-ever small artery occlusion (SAO) within 72 h of onset were enrolled, with a mean age of 63.83 ± 10.92 years, of whom 75 (65.2%) were male. FIELD STRENGTH/SEQUENCE: 1.5T or 3T; fast spin-echo for T1- and T2-weighted imaging, fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging (SWI). ASSESSMENT: Two neurologists independently evaluated the conventional MRI biomarkers of CSVD, including WMH, enlarged perivascular spaces, lacunes (LAC), and cerebral microbleeds; fasting blood samples were collected both within 72 h and between 8 and 14 days after the onset of the disease to measure MGO. STATISTICAL TESTS: T-test, Wilcoxon Mann-Whitney test, chi-square test, Spearman correlation analysis, ANOVA or the Kruskal-Wallis test; logistic regression analysis, intraclass correlation coefficient (ICC). p < 0.05 was considered statistically significant. RESULTS: Elevated MGO levels at admission were independently associated with CSVD (odds ratio [OR] 1.007, 95% confidence interval [CI] 1.002-1.011), and the severity of WMH (OR 1.004, 95% CI 1.001-1.008) and deep white matter hyperintensities (D-WMH) (OR 1.004, 95% CI 1.000-1.007). MGO levels also showed a positive correlation with LAC (correlation coefficient [r] = 0.225) but no significant correlation with periventricular white matter hyperintensities (PV-WMH) (r = 0.172, p = 0.066). Furthermore, there was no significant difference in MGO levels between admission and discharge (t = 1.932, p = 0.056). The reproducibility of MRI parameters was excellent (ICC 0.966-0.976). DATA CONCLUSION: Elevated MGO levels in patients with first-ever SAO were associated with the presence and severity of WMH, particularly D-WMH. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 1.
BACKGROUND: Although the clear cell likelihood score (ccLS) v2.0 demonstrates high specificity for clear cell renal cell carcinoma (ccRCC), its performance to characterize general malignancy in small renal masses (SRMs)...BACKGROUND: Although the clear cell likelihood score (ccLS) v2.0 demonstrates high specificity for clear cell renal cell carcinoma (ccRCC), its performance to characterize general malignancy in small renal masses (SRMs) remains limited. PURPOSE: To develop and validate a modified clear cell likelihood score (m-ccLS) incorporating the pseudocapsule to improve malignancy detection in SRMs while preserving specificity for diagnosing ccRCC. STUDY TYPE: This study was retrospective in type. SUBJECTS: 352 patients with pathologically proven SRMs were included: development (n = 235), internal validation (n = 60), and external validation (n = 57). FIELD STRENGTH/SEQUENCE: Imaging was performed at 3.0 and 1.5 T using fast spin-echo T2-weighted imaging, single-shot echo planar diffusion-weighted imaging, 3D spoiled gradient echo (GRE) T1-weighted dynamic contrast-enhanced imaging, and in- and opposed-phase using T1-weighted GRE. ASSESSMENT: 14 radiologists blinded to histopathology independently evaluated each SRM using ccLS v2.0 and m-ccLS scores in separate reading sessions; four, five, and five readers interpreted the development, internal, and external cohorts, respectively. STATISTICAL TESTS: Random-effects logistic regression, receiver operating characteristic curve, DeLong test, net reclassification improvement (NRI), integrated discrimination improvement (IDI), and Fleiss Kappa test were used. The statistical significance level was p < 0.05. RESULTS: For malignancy detection, m-ccLS showed a significantly higher area under the curve (AUC) than ccLS v2.0 across the development (0.850 vs. 0.772), internal validation (0.856 vs. 0.779), and external validation (0.803 vs. 0.720) cohorts with improved classification (NRI = 0.270, 0.045, and 0.028) and discrimination (IDI = 0.132, 0.206, and 0.120). For diagnosing ccRCC, m-ccLS and ccLS v2.0 showed similar results (0.908 vs. 0.894, p = 0.250; 0.912 vs. 0.898, p = 0.134; 0.865 vs. 0.838, p = 0.065) in development, internal, and external validation cohorts, respectively. m-ccLS category 3 contained fewer ccRCCs (33.3% vs. 72.5%; 15.8% vs. 47.2%; 7.6% vs. 26.9%) and malignancies (79.2% vs. 88.7%; 71.6% vs. 73.0%; 55.4% vs. 63.9%) than ccLS v2.0 category 3. DATA CONCLUSION: m-ccLS improves malignancy detection in SRMs compared with ccLS v2.0 without impairing diagnostic performance for ccRCC. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 2.
Glandorf J, Klein MM, Klimeš F
… +8 more, Kern AL, Gutberlet M, Hohlfeld JM, Hoeper MM, Olsson KM, Wacker F, Vogel-Claussen J, Voskrebenzev A
J Magn Reson Imaging
· 2026 May · PMID 41619314
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BACKGROUND: The pulsatile expansion of pulmonary vessels carries dynamic cardiopulmonary information that may reveal disease earlier than structural changes alone. PURPOSE: To test (i) intra- and inter-scan repeatability...BACKGROUND: The pulsatile expansion of pulmonary vessels carries dynamic cardiopulmonary information that may reveal disease earlier than structural changes alone. PURPOSE: To test (i) intra- and inter-scan repeatability of dynamic vessel metrics in healthy subjects, and (ii) whether chronic obstructive pulmonary disease (COPD) and postcapillary pulmonary hypertension (PH) exhibit disease-specific differences. STUDY TYPE: Retrospective, multi-cohort feasibility study with repeatability sub-study. SUBJECTS: Healthy: 29 (11 female), COPD: 52 (15 female), PH: 25 (15 female) with isolated postcapillary PH. FIELDSTRENGTH/SEQUENCE: 1.5T, free-breathing spoiled gradient-echo sequence, TE = 0.82 ms, TR = 3 ms, flip angle = 5°. ASSESSMENT: 2D U-Nets segmented pulmonary vessels throughout each series of 250 images. Dynamic metrics included the coefficient of variation (CV) of vessel area and CV of vessel signal. Delay between vessel signal and vessel expansion as %-of-RR-interval (SE-delay) together with the heart rate and lung area were calculated. STATISTICAL TESTS: Repeatability: Friedman; intraclass correlation coefficient (ICC); standard error of measurement (SEM) and the minimal detectable change (MDC). Group comparisons: Kruskal-Wallis and multiple linear regression. p < 0.05 was considered significant. RESULTS: Only the heart rate and the SE-delay presented significant changes across repetitive scans. Differences in Bland-Altman plots were evenly distributed across the range of measurements and symmetrically scattered around zero within 95% confidence intervals (mean bias 0.08%-5.12%). Across cohorts, CV vessel area and CV lung area differed significantly, showing lowest variability in COPD (2.67%; 7.03%) and highest in PH (4.58%; 16.74%). SE-delay was significantly prolonged in COPD (81.98%) compared to PH (67.20%) and healthy participants (62.97%). Cohort status (Healthy/COPD/PH) remained the strongest significant predictor for all parameters after adjustment (F-values 4.62-34.04), while age and gender had no significant influence (p > 0.391; p > 0.069). DATA CONCLUSION: Free-breathing lung MRI with automated vessel segmentation reveals distinct hemodynamic characteristics in COPD and PH. This method shows potential as a sensitive non-invasive tool for detection, phenotyping, and treatment monitoring in pulmonary pathology. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: 2.
BACKGROUND: Tertiary lymphoid structures (TLS) are associated with enhanced antitumor immune activity in hepatocellular carcinoma (HCC). Dynamic contrast-enhanced (DCE)-MRI-based habitat imaging may enable noninvasive TL...BACKGROUND: Tertiary lymphoid structures (TLS) are associated with enhanced antitumor immune activity in hepatocellular carcinoma (HCC). Dynamic contrast-enhanced (DCE)-MRI-based habitat imaging may enable noninvasive TLS identification. PURPOSE: To develop and validate a DCE-MRI-based habitat model to noninvasively identify TLS status in HCC. STUDY TYPE: Retrospective. SUBJECTS: Three hundred and thirty-four patients (mean age, 53.59 years ±11.38; male = 296; training set:test set = 200:134) with pathologically confirmed HCC. FIELD STRENGTH/SEQUENCE: 1.5-T/3.0-T, contrast-enhanced three-dimensional gradient-recalled-echo T1-weighted sequence. ASSESSMENT: Tumor habitats were identified from DCE-MRI via k-means clustering of voxel-wise enhancement patterns. Habitat-derived features and radiomics features were extracted. Five identification models were developed: clinical model, radiomics model, habitat model, clinical-radiomics model, and clinical-radiomics-habitat (hybrid) model. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC). STATISTICAL TESTS: Receiver operating characteristic (ROC) curve analysis, area under the precision-recall curve (AUPRC), DeLong test, decision curve analysis, Spiegelhalter's Z test. Significance level: p < 0.05 (two-sided). RESULTS: Four habitats with distinct dynamic enhancement patterns were identified. The hybrid model demonstrated the highest discrimination in the training and test sets (AUC = 0.83 [95% CI: 0.78, 0.89] and 0.84 [95% CI: 0.78, 0.91]). It significantly outperformed the clinical-radiomics model (AUC = 0.78 [95% CI: 0.72, 0.84] and 0.77 [95% CI: 0.69, 0.85]), radiomics model (AUC = 0.76 [95% CI: 0.70, 0.83] and 0.75 [95% CI: 0.67, 0.83]), and clinical model (AUC = 0.70 [95% CI: 0.63, 0.78] and 0.68 [95% CI: 0.58, 0.77]) in both sets. Compared to the habitat model (AUC = 0.78 and 0.80), the hybrid model showed significantly better training performance but comparable test performance (p = 0.09). CONCLUSION: A hybrid model combining clinical, radiomics, and habitat-derived features was developed for identifying TLS status. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Visual decline in dural arteriovenous fistulae (DAVF) patients is attributed to venous hypertension, raised intracranial pressure and resultant optic nerve axoplasmic flow stasis. Objective imaging biomarkers...BACKGROUND: Visual decline in dural arteriovenous fistulae (DAVF) patients is attributed to venous hypertension, raised intracranial pressure and resultant optic nerve axoplasmic flow stasis. Objective imaging biomarkers for optic nerve involvement are however limited. PURPOSE: To determine whether 3D fluid attenuated inversion recovery (FLAIR) optic nerve signal intensity ratio (SIR) is associated with papilledema and visual deterioration in DAVF patients. STUDY TYPE: Single-center retrospective observational study. POPULATION: 54 digital subtraction angiography (DSA) confirmed DAVF patients (27 with papilledema; 27 without) with 3D FLAIR MRI, together with 27 matched controls. FIELD STRENGTH/SEQUENCE: 3D FLAIR sequence at 3.0 T. ASSESSMENT: Three blinded neuroradiologists evaluated segmental normalized optic-nerve SIR. The primary outcome was status of papilledema (fundoscopy)/visual deterioration (Snellen's visual acuity charting). Secondary outcomes included segmental optic nerve hyperintensity (measured by SIR and qualitative assessment) and visual response (improved, stable or worsened visual acuity) post-embolization. All patients underwent endovascular embolization with repeat neuro-ophthalmologic evaluation and imaging (short term followup at 1 month and long term at 1 year). STATISTICAL TESTS: Unpaired t-test, Mann-Whitney U, repeated-measures ANOVA, Receiver Operating Characteristic (ROC) curve; Interobserver agreement with Krippendorff's alpha and intraclass correlation coefficient (ICC); Correlation analysis with Spearman correlation; p value < 0.05 was considered significant. RESULTS: Optic nerve SIR differed significantly across groups, with highest values in patients with visual decline. The intracanalicular segment was most commonly involved (51.8%). An SIR cutoff of 1.7 showed association of papilledema with visual loss (AUC = 0.725; 95% CI: 0.608-0.858; 48.2% had visual deterioration), yielding 79.2% sensitivity and 63.3% specificity. Follow-up included repeat ophthalmologic evaluation and imaging, with 23.1% patients showing improvement at a mean follow-up of 1.7 ± 1.6 years. CONCLUSION: 3D FLAIR MRI may detect optic nerve signal changes in DAVF patients, with elevated intracanalicular SIR correlating with papilledema and visual decline. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 5.
Alam FS, Munidasa S, Zanette B
… +4 more, Li D, Braganza S, Ratjen F, Santyr G
J Magn Reson Imaging
· 2026 Jun · PMID 41609189
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BACKGROUND: Elexacaftor/tezacaftor/ivacaftor (ETI) is a current standard therapy for pediatric cystic fibrosis (CF). Multiple-breath washout Xe MRI (MBW Xe-MRI) is improved following 1 month of treatment. However, the ut...BACKGROUND: Elexacaftor/tezacaftor/ivacaftor (ETI) is a current standard therapy for pediatric cystic fibrosis (CF). Multiple-breath washout Xe MRI (MBW Xe-MRI) is improved following 1 month of treatment. However, the utility of MBW Xe-MRI over extended ETI treatment and its comparison to single-breath Xe-MRI and pulmonary function tests (PFTs) in monitoring disease progression remains unclear. PURPOSE: To compare MBW Xe-MRI and single-breath Xe-MRI in a small pediatric CF cohort at 1, 6, 12, and 24 months post-ETI initiation. STUDY TYPE: Prospective longitudinal cohort study. SUBJECTS: 14 participants (7 female, median age 15.5 [14, 17] years) with CF undergoing ETI. FIELD STRENGTH/SEQUENCE: Xe-MRI using a gradient echo sequence at 3T. ASSESSMENT: A total of 12 participants completed MBW Xe-MRI, single-breath Xe-MRI, and PFTs (spirometry, N MBW) at ≥ 2 of 4 visits (1, 6, 12, and 24 months post-ETI). Fractional ventilation (FV) and FV coefficient of variation (CoV) maps were calculated from MBW Xe-MRI. Ventilation defect percent (VDP) was calculated from single-breath Xe-MRI. STATISTICAL TESTS: Longitudinal changes were analyzed using a linear mixed-effects model (fixed effect: time, random intercept: participant). Significance via ANOVA F-test, p < 0.05. Intra-class correlation coefficients (ICC) were used to quantify between- and within-subject variability. RESULTS: Data completeness (total number of acquired data points divided by expected data points across 14 participants, 4 visits) was ≥ 75%. While PFTs/VDP remained stable over 24 months (ICC ≥ 0.93; linear mixed-effects model of time effect for ppFEV, LCI and VDP was not significant with p = 0.68, 0.13 and 0.12, respectively), CoV demonstrated a small but significant increase (slope magnitude +0.001/month). Furthermore, two participants had elevated CoV despite normal VDP. Finally, MBW Xe-MRI metrics showed higher within-subject variability than PFTs/VDP (ICC: FV = 0.41, CoV = 0.55 vs. VDP/PFTs ≥ 0.92). DATA CONCLUSION: CoV may continue to evolve over 2 years in pediatric CF patients receiving ETI, particularly in individuals with persistent ventilation defects. EVIDENCE LEVEL: 1. STAGE OF TECHNICAL EFFICACY: 2.
J Magn Reson Imaging
· 2026 May · PMID 41607039
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BACKGROUND: Upper-airway morphology changes during breathing can be captured with cine 4D MRI. Active-learning nnU-Net reduces manual labeling while maintaining accuracy. PURPOSE: For automatic upper airway segmentation...BACKGROUND: Upper-airway morphology changes during breathing can be captured with cine 4D MRI. Active-learning nnU-Net reduces manual labeling while maintaining accuracy. PURPOSE: For automatic upper airway segmentation on free-breathing cine 4D MRI using active learning and quantifying dynamic changes under two mouth positions. STUDY TYPE: Prospective cross-sectional study. POPULATION: Eighty-four OSA (obstructive sleep apnea)-free adults (28 M/56F; 18-80 years; 33 with sleep-related breathing symptoms). Segmentation performance was evaluated on an internal test set (n = 18). FIELDSTRENGTH/SEQUENCE: 3T, free-breathing time-resolved imaging with interleaved stochastic trajectories (TWIST) sequence under closed- and open-mouth positions. ASSESSMENT: Manual annotations by a technologist (radiologist-verified) served as reference standard and training labels for an active-learning nnU-Net (68 training; four fixed validation). Total airway length, cross-sectional area (CSA), and total airway volume were computed at each anatomical level and compared across mouth positions, sex, and sleep-related symptom status, and independent predictors were identified. STATISTICAL TESTS: Paired/unpaired t or Mann-Whitney U test (two-sided p = 0.05). Predictor selection by 10-fold LASSO; effects estimated via ordinary least squares with cluster-robust standard errors. RESULTS: Segmentation achieved a dice 0.959 ± 0.019 (test set). Open-mouth breathing significantly lengthened the total airway (7.92 ± 1.07 vs. 7.41 ± 0.93 cm) and reduced retropalatal CSA (1.51 ± 0.68 vs. 1.80 ± 0.69 cm). Coefficients of variation (CVs) for CSA and volume were significantly higher with 20-s open-mouth breathing. Males (n = 28) exhibited significantly larger airway volumes than females (closed 27.94 ± 4.87 vs. 19.82 ± 3.26 cm; open 30.26 ± 5.94 vs. 20.94 ± 3.85 cm). Symptomatic individuals (n = 33) had significantly longer airways (closed 7.96 ± 0.96 vs. 7.04 ± 0.70 cm; open 8.54 ± 1.01 vs. 7.52 ± 0.91 cm), narrower open-mouth retropalatal CSA (1.24 ± 0.51 vs. 1.68 ± 0.72 cm), and greater retropalatal CSA dynamic variability. Multivariable regression confirmed mouth position, symptoms, and sex as independent predictors. DATA CONCLUSION: Four-dimensional cine MRI with active-learning nnU-Net can automatically quantify dynamic upper airway morphology, demonstrating systematic differences and dynamic variability. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 2.
Arvidsson J, Eriksson S, Jalnefjord O
… +3 more, Johansson E, Nordanstig J, Lagerstrand K
J Magn Reson Imaging
· 2026 Mar · PMID 41604213
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BACKGROUND: Skeletal muscle blood oxygen level dependent (BOLD) MRI is a technique for assessing vascular function in peripheral limbs. In patients, however, an increased frequency of atypical response patterns has been...BACKGROUND: Skeletal muscle blood oxygen level dependent (BOLD) MRI is a technique for assessing vascular function in peripheral limbs. In patients, however, an increased frequency of atypical response patterns has been observed, warranting investigation into its underlying causes. PURPOSE: To explore the dynamics of cuff-induced ischemia and reactive hyperemia with BOLD MRI, focusing on the occurrence, quantification, and interpretation of frequent atypical cuff-induced response patterns. STUDY TYPE: Secondary assessment of prospectively collected datasets. POPULATION: Seventeen peripheral artery disease (PAD) patients (age: 64-80 years, ankle-brachial index (ABI) range: 0.4-0.8), 8 age-matched controls (age: 64-82 years, ABI range: 1-1.2), and 14 young controls (age: 22-39 years). FIELD STRENGTH/SEQUENCE: -weighted multi-echo gradient-echo sequence with 11 equidistant echo-times at 3T. ASSESSMENT: A transverse slice of the calf was imaged repeatedly during an upper-thigh cuff compression cycle consisting of 1-min baseline, 5-min arterial occlusion (cuff inflated) and 5-min reactive hyperemia (cuff deflated). -mapping with ROI-wise analysis of the soleus and gastrocnemius muscles produced -time curves and previously established metrics, including the hyperemic upslope ( ) and time-to-peak (TTP) were assessed. The time-curves were surveyed to identify the frequency and type of deviations from expected. -time curves of soleus were further analyzed by fitting a parameterized function to derive additional metrics including depth of the undershoot on cuff release and deviation from a monotonic T2* decrease. Ankle-brachial index (ABI) served as a clinical reference for comparisons. STATISTICAL TESTS: Non-parametric 2-tailed Wilcoxon rank-sum tests to assess differences between patients and age-matched controls. A p value < 0.05 was considered significant. RESULTS: Atypical cuff-induced response patterns in PAD patients included a negative cuff-induced transient (42%, soleus) and non-monotonic declines in during cuffing (58%, soleus). While these contributed to increased variabilities in patients, (-0.63 ms/s) and TTP (62.8 s) between patients and age-matched controls. DATA CONCLUSION: HS and TTP provided means to quantify calf muscle responses to cuffing. Specific cases of non-monotonous decrease during cuffing suggest the detection of venous valve leakages in inter-muscular veins. Insufficient cuff pressure produced curves with absent ischemic plateau and weak hyperemic responses, the recognition of which is important to prevent physiological misinterpretations of curves and derived metrics. EVIDENCE LEVEL: 1. TECHNICAL EFFICACY: 3.
Liu Z, Liu Z, Rashid I
… +7 more, Galizia MS, Scoma C, Truesdell W, Agarwal P, Seiberlich N, Shen L, Hamilton J
J Magn Reson Imaging
· 2026 May · PMID 41569085
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BACKGROUND: 0.55T systems offer unique advantages and may support expanded access to cardiac MRI. PURPOSE: To assess the feasibility of 0.55T cardiac MR Fingerprinting (MRF), leveraging a deep image prior reconstruction...BACKGROUND: 0.55T systems offer unique advantages and may support expanded access to cardiac MRI. PURPOSE: To assess the feasibility of 0.55T cardiac MR Fingerprinting (MRF), leveraging a deep image prior reconstruction to mitigate noise. STUDY TYPE: Phantom and prospective in vivo assessment. POPULATION: ISMRM/NIST MRI system phantom and 18 healthy subjects (11 female; ages 28 ± 8 years). FIELD STRENGTH AND SEQUENCES: MRF, modified Look-Locker inversion recovery (MOLLI), and T-prepared balanced steady state free precession (T-bSSFP) at 0.55T. ASSESSMENT: MRF T and T maps were reconstructed using (1) a low-rank technique with sparse and locally low-rank regularization (SLLR-MRF) and (2) a deep image prior (DIP-MRF). Accuracy and precision of MRF and conventional sequences were evaluated in a phantom. In vivo performance of MRF was evaluated in the 18 healthy subjects, with 7 subjects also undergoing conventional mapping. Myocardial T and T values were compared among methods and image quality scored by three readers (2, 3, and 4 years of experience) on a 5-point scale. STATISTICAL TESTS: Linear regression, Bland-Altman, intraclass correlation coefficient, and one-way ANOVA with p < 0.05 considered significant. RESULTS: Mean measurements in the left ventricular septum were 671 ± 31 ms (MOLLI), 761 ± 147 ms (SLLR-MRF), and 686 ± 39 ms (DIP-MRF) for T, and 63.5 ± 5.7 ms (T-bSSFP), 47.5 ± 12.7 ms (SLLR-MRF), and 45.2 ± 4.5 ms (DIP-MRF) for T. Compared to conventional mapping, DIP-MRF exhibited significantly lower T but no differences in T (p > 0.99). Standard deviations within the myocardium were significantly lower with DIP-MRF compared to SLLR-MRF (39 vs. 147 ms for T and 4.5 vs. 12.7 ms for T). Overall image quality ratings were significantly lower for SLLR-MRF (T: 2.3, T: 2.9), which were significantly lower compared to conventional mapping methods (T: 3.4, T: 3.9), and DIP-MRF (T: 3.8, T: 4.1) received higher scores. DATA CONCLUSION: This study demonstrated the feasibility of cardiac MRF on a commercial 0.55T system, enabled by a deep image prior reconstruction for denoising. EVIDENCE LEVEL: 2. STAGE OF TECHNICAL EFFICACY: 1.
BACKGROUND: Gadopiclenol is a high-relaxivity contrast agent enabling dose reduction while maintaining image quality. However, comparison with conventional agents remains limited in body MRI. PURPOSE: To intra-individual...BACKGROUND: Gadopiclenol is a high-relaxivity contrast agent enabling dose reduction while maintaining image quality. However, comparison with conventional agents remains limited in body MRI. PURPOSE: To intra-individually compare half-dose gadopiclenol and standard-dose gadobenate for image quality and lesion conspicuity in abdominal MRI. STUDY TYPE: Retrospective. POPULATION: One hundred patients (55 men; mean age: 64 ± 14 years) who underwent both abdominal MRI with gadobenate (0.1 mmol/kg) and gadopiclenol (0.05 mmol/kg) on the same scanner within 12 months. FIELD STRENGTH/SEQUENCE: 1.5T/3T, dynamic T1-weighted imaging pre-contrast, early arterial (EAP), late arterial (LAP), portal venous (PVP), and equilibrium phases (EP) using 3D fat-suppressed gradient echo sequence. ASSESSMENT: Signal intensity of liver, pancreas, spleen, kidneys, aorta, portal vein, and abdominal lesions was measured on each phase except EAP. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and magnitude of contrast enhancement (ΔE) were calculated for organs. In lesions, lesion-to-background ratio (LBR) and ΔE were calculated. Subjective image quality and lesion conspicuity were assessed by three readers using a 5-point Likert scale. STATISTICAL TESTS: Paired t-test and Wilcoxon test. p < 0.05 indicated statistically significant results. RESULTS: Gadopiclenol yielded significantly higher CNR and SNR for pancreas, portal vein, and kidney in LAP. No significant differences in CNR (p: 0.372-0.858) and SNR (p: 0.433-0.936) were found in PVP. In EP, gadobenate showed higher hepatic CNR, while CNR and SNR of all other organs were comparable (p: 0.103-0.912). Gadopiclenol showed higher pancreatic ΔE in all enhanced phases. LBR and ΔE of 21 evaluated lesions were comparable across all phases (p: 0.100-0.821). No significant differences were observed in readers' perception of lesion enhancement (p: 0.059-0.957). CONCLUSION: Half-dose gadopiclenol provides comparable subjective image quality and lesion conspicuity to standard-dose gadobenate, with superior pancreatic, kidney, and portal vein enhancement in LAP, and similar performance in PVP and EP.