BACKGROUND: MRI is important for cardiac disease evaluation, but accurate diagnosis remains challenging in less experienced centers. Although large language models (LLMs) have shown promise in medical imaging diagnosis,...BACKGROUND: MRI is important for cardiac disease evaluation, but accurate diagnosis remains challenging in less experienced centers. Although large language models (LLMs) have shown promise in medical imaging diagnosis, their application in cardiac MRI is limited. HYPOTHESIS: LLMs may be effective in achieving cardiac MRI diagnosis based on standardized descriptions. STUDY TYPE: Retrospective. POPULATION: A total of 203 hypertrophic cardiomyopathy, 186 dilated cardiomyopathy, 46 hypertensive heart disease, 198 ischemic cardiomyopathy, 38 constrictive pericarditis, 45 cardiac amyloidosis, 91 myocarditis, and 144 normal controls. FIELD STRENGTH/SEQUENCES: Balanced steady-state free-precession, short tau inversion recovery, and breath-hold inversion-recovery segmented gradient-echo sequences at 3.0 T. ASSESSMENT: Clinical and cardiac MRI information from each subject was converted into standardized descriptions and input into Generative Pre-trained Transformer-4.5 (GPT-4.5), GPT-4 Omni (GPT-4o), Deepseek-V3, and Deepseek-R1 LLMs. Cardiac MRI information included LV function, wall thickness and motion, and abnormalities on T2WI, perfusion and late gadolinium enhancement sequences. Each model was asked to generate an imaging diagnosis. In addition, a medical student (8 months experience) and three radiologists (junior, mid-level and senior: with 3, 6, and 10 years' experience, respectively) provided diagnoses based on cardiac MRI images and clinical information. STATISTIC TESTS: Frequency-weighted sensitivity and specificity were calculated. The diagnostic performances of the LLMs and human readers were compared using the McNemar test with Bonferroni correction. A p value < 0.05 was considered significant. RESULTS: All LLMs showed excellent frequency-weighted specificity (0.973-0.983). The frequency-weighted sensitivities of all LLMs were not significantly different from that of the junior radiologist, were significantly higher than that of the medical student, and significantly inferior to those of the senior radiologist (GPT-4.5: 0.863, GPT-4o: 0.821, Deepseek-V3: 0.843, and Deepseek-R1: 0.851 vs. junior radiologist: 0.850, all adjusted p = 1.000; vs. medical student: 0.731, all adjusted p < 0.001; vs. senior radiologist: 0.942, all adjusted p < 0.001). Additionally, the mid-level radiologist achieved a frequency-weighted sensitivity of 0.895, outperforming all LLMs except GPT-4.5. DATA CONCLUSION: LLMs may generate accurate diagnoses from standardized cardiac MRI descriptions, potentially benefiting less experienced physicians. TECHNICAL EFFICACY: Stage 5.
BACKGROUND: Clinical T-weighted (T2W) MRI of prostate cancer (PCa) usually implements a 2D fast-spin-echo (FSE) sequence, but understanding the echo-time-dependent contrast behavior is not straightforward due to the comp...BACKGROUND: Clinical T-weighted (T2W) MRI of prostate cancer (PCa) usually implements a 2D fast-spin-echo (FSE) sequence, but understanding the echo-time-dependent contrast behavior is not straightforward due to the complicated FSE signal evolution. Consequently, consensus-based recommendations on the optimal effective echo time (TE) to maximize contrast are lacking. PURPOSE: To investigate the effect of TE on PCa lesion contrast in prostate T2W MRI. STUDY TYPE: Phantom and in vivo prospective study. SUBJECTS: A standard MRI phantom and 53 prostate cancer patients (29 for image evaluation and 24 for quantitative lesion analysis). FIELD STRENGTH AND SEQUENCE: Multi-slice T2W FSE sequence at 3 T acquired at multiple TE values. ASSESSMENT: Three readers (13, 25, and 27 years' experience) evaluated TE = 100 ms versus 150 ms on diagnostic quality and reader preference. The effective T relaxation rates (T) were measured using FSE sequences in the phantom and used to predict the optimal TE maximizing T2W contrasts. From multi-TE scans of subjects with suspected PCa, T values of PCa lesions and healthy tissue were measured and used to calculate the optimal TE maximizing the lesion contrast. In vivo contrast metrics were measured as a function of TE. STATISTICAL TESTS: Wilcoxon test of reader scores, with p < 0.05 defining statistical significance. RESULTS: No statistically significant difference was found in diagnostic quality between TE = 150 ms and 100 ms images, but all three readers significantly favored TE = 150 ms. Phantom experiments demonstrated that TE-dependent FSE signal progression can be characterized by T values typically 40% longer than actual T values, allowing accurate prediction of optimal TE within 2%-5%. Applied to PCa imaging, in vivo measurements indicated that effective T relaxation times of the prostate are on average 1.5× longer than published T values. DATA CONCLUSION: The benefits of TE = 150 ms versus 100 ms in prostate T2W FSE were supported by reader preference, phantom experiments, in vivo measurements, and analytic optimizations. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: 2.
BACKGROUND: The demand for cardiac MRI is increasing with the growing burden of cardiovascular disease. However, conventional protocols require sequential acquisitions for multi-breath-hold 2D cine and 3D MR angiography...BACKGROUND: The demand for cardiac MRI is increasing with the growing burden of cardiovascular disease. However, conventional protocols require sequential acquisitions for multi-breath-hold 2D cine and 3D MR angiography (MRA), which is time-consuming. In addition, breath-hold 2D cine can be challenging for patients with limited breath-hold capacity. PURPOSE: To further develop and evaluate a free-breathing 3D whole-heart cine MRI technique for simultaneous assessment of cardiac function and aortic anatomy in a single non-contrast acquisition at 1.5 T. STUDY TYPE: Prospective. SUBJECTS: Twenty-four healthy volunteers (mean age 31.8 ± 9.9 years, 50% female). FIELD STRENGTH/SEQUENCES: 1.5 T; A cartesian spiral (CASPR) bSSFP 3D cine, 2D cine and 3D mDixon MRA. ASSESSMENT: Acquisition and reconstruction times were assessed for 3D cine at 2.5 and 2.0 mm. LV mass, LVEF, and RVEF were assessed by two observers (5 and 32 years of experience) and compared with 2D cine. Aortic root and ascending aortic areas were compared with 3D MRA. Image quality was evaluated using blood pool-to-myocardium contrast ratio and endocardial/epicardial edge sharpness. Qualitative image preference was assessed by three observers (5, 32, and 33 years of experience). STATISTICAL TESTS: One-way ANOVA with Tukey post hoc tests and Bland-Altman analysis with paired t-tests were used. Intraclass correlation coefficient (ICC) assessed inter- and intra-observer agreement. p < 0.05 was considered significant. RESULTS: Acquisition time was 5 min (2.5 mm) and 7 min (2 mm), versus 11 min for 2D cine and 8 min for 3D MRA. Reconstruction time was approximately 5 min. LV mass showed no differences versus 2D cine. LVEF showed small but significant bias (2.5 mm: 1.38%, p = 0.005; 2.0 mm: 1.39%, p < 0.001). RVEF showed no significant differences. Ascending aorta areas showed significant differences (0.28mm and 0.25mm, p < 0.001), while aortic root areas showed no difference versus 3D MRA. Reproducibility was at least moderate (ICC 0.75-0.998). 3D cine showed lower contrast and edge sharpness than 2D cine (p < 0.001). Observers preferred 2.0 mm (ICC = 0.64). DATA CONCLUSION: Free-breathing 3D cine MRI enables operator-independent, time-efficient, and accurate assessment of cardiac function and aortic anatomy in healthy volunteers in a single non-contrast acquisition at 1.5 T, compared to conventional 2D cine and 3D MRA. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 1.
BACKGROUND: Glutamate chemical exchange saturation transfer (GLU-CEST) is a non-invasive in vivo approach for glutamate detection, but its performance for glioma evaluation at 5T remains incompletely defined. PURPOSE: To...BACKGROUND: Glutamate chemical exchange saturation transfer (GLU-CEST) is a non-invasive in vivo approach for glutamate detection, but its performance for glioma evaluation at 5T remains incompletely defined. PURPOSE: To investigate factors influencing 5T GLU-CEST and its diagnostic value in glioma stratification. STUDY TYPE: Prospective. PHANTOM AND POPULATION: Five phantom series (pH 6.2-7.4; glutamate 8-20 mM) and 40 adult-type diffuse glioma patients (49.00 ± 12.26 years; 23 males). FIELDSTRENGTH/SEQUENCE: 5 T, fast spin-echo GLU-CEST and amide proton transfer (APT)-CEST. ASSESSMENT: Phantoms and patients underwent MRI scans; GLU-CEST, APT-CEST, and normalized values (ΔGLU-CEST, ΔAPT-CEST) were quantified. Gliomas were graded by WHO 2-4; IDH status was determined. STATISTICAL TESTS: Spearman correlation, Kruskal-Wallis tests, Mann-Whitney U tests, and weighted DeLong tests; two-sided p < 0.05 was significant. RESULTS: GLU-CEST signals positively correlated with glutamate and negatively with pH (ρ ≥ 0.893). Significant differences were found in all effects between WHO Grade 2 and 4 gliomas (ΔGLU-CEST: 2.006 [1.143, 2.799] vs. 4.365 [2.974, 5.299]; GLU-CEST: 7.424 [6.679, 7.649] vs. 10.155 [8.098, 11.550]; ΔAPT-CEST: 1.918 [1.258, 2.461] vs. 3.386 [2.682, 4.805]; APT-CEST: 1.961 [1.425, 2.715] vs. 3.333 [2.478, 4.632]), whereas only ΔGLU-CEST and GLU-CEST exhibited significant disparities between Grade 3 and 4 gliomas (ΔGLU-CEST: 2.171 [1.895, 2.862] vs. 4.365 [2.974, 5.299]; GLU-CEST: 7.102 [6.475, 7.259] vs. 10.155 [8.098, 11.550]). In the solid tumor region, all effects demonstrated significant differences between IDH-mutant and IDH wild-type gliomas (ΔGLU-CEST: 2.111 [1.614, 3.110] vs. 4.333 [2.964, 5.405]; GLU-CEST: 7.259 [6.577, 7.726] vs. 10.291 [8.097, 11.634]; ΔAPT-CEST: 2.017 [1.355, 2.718] vs. 3.235 [2.670, 4.735]; APT-CEST: 2.122 [1.680, 2.889] vs. 3.270 [2.450, 4.262]), whereas GLU-CEST outperformed APT-CEST and ΔAPT-CEST in diagnostic efficacy (AUC difference = 0.073 and 0.101). DATA CONCLUSION: 5 T GLU-CEST is capable of differentiating between grade 2 and grade 4, as well as grade 3 and grade 4 adult diffuse gliomas, and demonstrates superior performance to APT-CEST in the classification of IDH status. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Poor cardiac MR image quality can prompt repeat examinations and hinder clinical decision-making. PURPOSE: To evaluate whether pre-imaging clinical information, extracted using a large language model (LLM), i...BACKGROUND: Poor cardiac MR image quality can prompt repeat examinations and hinder clinical decision-making. PURPOSE: To evaluate whether pre-imaging clinical information, extracted using a large language model (LLM), is independently associated with cardiac MR image quality. STUDY TYPE: Retrospective. POPULATION: 1006 adults undergoing clinical cardiac MR examinations. FIELD STRENGTH/SEQUENCE: 1.5 T and 3 T scanners with cine, black blood, MR angiogram, or late gadolinium enhancement protocols. ASSESSMENT: Image quality was categorized per study as excellent, slightly limited, severely limited, or nondiagnostic using institutional reporting conventions finalized by radiologists and cardiologists. A HIPAA-compliant LLM assigned image quality labels based on radiology reports through an iteratively refined prompt, with reliability confirmed by two radiologists. Labels were binarized as Good (excellent and slightly limited) versus Poor (severely limited and nondiagnostic). A repeat-imaging-adjusted image quality label was used in a sensitivity analysis. Pre-imaging clinical and patient variables were extracted from electronic health records. Associations between variables and image quality labels were investigated. STATISTICAL TESTS: Cohen's kappa (κ) for label agreement. Chi-square and t-tests for univariate analysis. Variance inflation factor (VIF) and multivariable logistic regression. Significance level: p < 0.05. RESULTS: Binarized image quality labels showed substantial agreement with interpreters' assessments for both the primary dataset (κ = 0.689) and the repeat-adjusted dataset (κ = 0.879). There was no significant multicollinearity (VIF = 1.01-1.39). Cognitive and communication impairment (OR 1.81, 95% CI [1.30-2.54], p < 0.001) and respiratory issues (1.57 [1.14-2.17], p = 0.006) were independently associated with poor image quality. These associations remained significant in the repeat-adjusted sensitivity analysis (cognitive and communication impairment (OR 1.75, 95% CI [1.27-2.44], p < 0.001) and respiratory compromise (OR 1.37, 95% CI [1.04-1.82], p = 0.027)). Other clinical variables were not independently associated after adjustment. DATA CONCLUSION: Cognitive/communication impairment and respiratory compromise were independently associated with poor cardiac MR image quality. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: On conventional carotid plaque MRI, calcification is commonly defined as a region that is hypointense across multiple contrast weightings. However, iron-containing components such as hemosiderin may exhibit s...BACKGROUND: On conventional carotid plaque MRI, calcification is commonly defined as a region that is hypointense across multiple contrast weightings. However, iron-containing components such as hemosiderin may exhibit similar signal characteristics, raising concerns regarding substrate specificity. PURPOSE: To evaluate whether quantitative susceptibility mapping (QSM) can distinguish hemosiderin from calcification in carotid atherosclerotic plaques using ex vivo MRI with direct histopathologic correlation. STUDY TYPE: Ex vivo specimen study. SPECIMEN: Twenty-four carotid endarterectomy specimens obtained between October 2017 and August 2021. FIELD STRENGTH/SEQUENCE: 3T MRI including spin-echo T1-weighted, spin-echo T2-weighted, time-of-flight-equivalent gradient-echo (FLASH) imaging, and multi-echo FLASH-based QSM reconstruction. ASSESSMENT: Histologic sections were stained with hematoxylin-eosin, von Kossa (calcification), and Berlin blue (hemosiderin). With histopathologic findings as reference, two radiologists defined corresponding regions of interest on MRI for substrate-level signal characterization. Contrast-to-noise ratios (CNR) were measured on conventional sequences, and relative susceptibility values (rSV) were measured on QSM. STATISTICAL TEST: Group comparisons were performed using the Wilcoxon rank-sum test. A two-sided p < 0.05 was considered statistically significant. RESULTS: Seventy-nine matched cross-sections yielded 41 calcifications and 25 hemosiderin deposits, including 16 sections with both components. On T1-, T2-, and FLASH imaging, CNR values did not differ significantly between calcification and hemosiderin (p = 0.12, p = 0.096, and p = 0.67, respectively), with substantial signal overlap. On QSM, hemosiderin exhibited positive rSVs (mean ± SD: 506.8 ± 320.5 ppb), whereas calcification exhibited negative rSVs (-440.5 ± 296.3 ppb), without polarity overlap in this dataset and with a significant group difference. Hemosiderin deposition was identified in 25 of 79 matched sections, and calcification and hemosiderin coexisted in 16 sections. DATA CONCLUSIONS: Hypointensity on conventional carotid plaque MRI may not reliably indicate calcification at the substrate level. QSM enables robust differentiation between diamagnetic calcium and paramagnetic iron with histopathologic validation. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Accurate imaging assessment of hepatocellular carcinoma (HCC) after stereotactic body radiotherapy (SBRT) remains challenging. Although LI-RADS CT/MRI Radiation Treatment Response Assessment (TRA v2024) was d...BACKGROUND: Accurate imaging assessment of hepatocellular carcinoma (HCC) after stereotactic body radiotherapy (SBRT) remains challenging. Although LI-RADS CT/MRI Radiation Treatment Response Assessment (TRA v2024) was developed for this purpose, its prognostic value for survival stratification after SBRT remains to be validated. PURPOSE: To compare the prognostic performance of mid-term (3-6 months) and late-term (9-12 months) MRI-based treatment response assessed using modified RECIST (mRECIST), LI-RADS TRA v2017, and LI-RADS Radiation TRA v2024 in patients with HCC. STUDY TYPE: Retrospective cohort study. POPULATION: 125 patients with HCC underwent SBRT (111 males; mean age, 56.4 ± 10.8 years). FIELD STRENGTH/SEQUENCE: 3.0 T; axial fat-suppressed fast spin-echo T2-weighted imaging, diffusion-weighted imaging, pre-contrast gradient recalled echo T1-weighted imaging, and contrast-enhanced late arterial phase, portal venous phase, and delayed/transitional phase. ASSESSMENT: Tumor response was independently evaluated by three radiologists using three treatment assessment methods. Ancillary features (AFs) were additionally recorded to assess their incremental prognostic value. Overall survival (OS) and progression-free survival (PFS) were analyzed according to response categories. STATISTICAL TESTS: Kolmogorov-Smirnov test, Intraclass correlation coefficients, Cohen's κ, Variance inflation factor analysis, Kaplan-Meier method, Log-rank tests with Bonferroni correction, Univariate and multivariable Cox regression analyses. Statistical significance was defined as p < 0.05. RESULTS: At mid-term follow-up, LI-RADS Radiation TRA v2024 showed greater discrimination for PFS than mRECIST and LI-RADS TRA v2017, with no OS difference (p > 0.999). Across all three criteria, late-term response assessment yielded better prognostic stratification for PFS and OS than did mid-term evaluation. At the late-term follow-up, LI-RADS Radiation TRA v2024 was strongly associated with OS (HR = 15.80, 95% CI: 3.34-75.00) and PFS (HR = 6.31, 95% CI: 2.68-14.90). Adding AFs provided no further prognostic improvement. DATA CONCLUSION: LI-RADS Radiation TRA v2024 demonstrates strong prognostic stratification after SBRT, particularly at late-term MRI evaluation. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Susceptibility map-weighted imaging (SMwI) provides high accuracy for early Parkinson's disease (ePD) by enhancing nigral hyperintensity. However, standard SMwI requires dedicated acquisition; reconstruction...BACKGROUND: Susceptibility map-weighted imaging (SMwI) provides high accuracy for early Parkinson's disease (ePD) by enhancing nigral hyperintensity. However, standard SMwI requires dedicated acquisition; reconstruction from routinely acquired sequences may offer a practical alternative. PURPOSE: To compare the diagnostic performance of standard SMwI with SWI- and neuromelanin (NM)-driven SMwI for differentiating ePD from disease controls (DC). STUDY TYPE: Retrospective. SUBJECTS: One hundred and eighty-seven drug-naïve ePD (age: 67.5 ± 9.4 years, 102 male) and 43 DC (age: 67.1 ± 9.2 years, 12 male). FIELD STRENGTH/SEQUENCE: 3 T, multi-echo gradient-echo (GRE) for standard SMwI; GRE-based NM imaging: multi-echo GRE for SWI. ASSESSMENT: Nigral hyperintensity was assessed by three neuroradiologists (4-, 2-, and 1-year experience). Diagnostic performance was evaluated using clinical diagnosis for all subjects and PET for 106 subjects (98 ePD, 8 DC). PET-based assessment included side-based analyses accounting for PET laterality and patient-based analyses regardless of direction. STATISTICAL TESTS: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and area under the curve (AUC) were assessed using clinical diagnosis as reference; sensitivity, specificity, and accuracy using PET. Significance was set at p < 0.05. RESULTS: Using clinical diagnosis as reference, standard SMwI showed highest diagnostic performance (sensitivity 0.856; specificity 1.000; PPV 1.000; AUC 0.928). SWI-driven SMwI maintained similar sensitivity (p = 0.355) but showed significantly reduced specificity, PPV, accuracy, AUC. In the PET subgroup, side- and patient-based analyses showed no differences in sensitivity (p = 0.261, p = 0.670), specificity (p = 1.000, p = 1.000) and accuracy (p = 0.268, p = 0.695) between standard and SWI-driven SMwI. DATA CONCLUSION: SWI-driven SMwI approached the diagnostic performance of standard SMwI with PET reference but showed inferior performance with clinical diagnosis, suggesting a fallback option when dedicated SMwI is unavailable. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 1.
BACKGROUND: Slab-selective radiofrequency (RF) pulses are commonly required in three-dimensional (3D) turbo spin echo (TSE) in brachial plexus magnetic resonance neurography (MRN). However, their long selective RF pulses...BACKGROUND: Slab-selective radiofrequency (RF) pulses are commonly required in three-dimensional (3D) turbo spin echo (TSE) in brachial plexus magnetic resonance neurography (MRN). However, their long selective RF pulses lead to violation of Carr-Purcell-Meiboom-Gill conditions, which might increase imaging artifacts. HYPOTHESIS: That VERSE STIR-TSE would yield comparable motion artifact to conventional STIR-TSE with superior nerve conspicuity and greater subjective appeal. STUDY TYPE: Prospective, cross-sectional study. POPULATION: Twenty-four subjects (16 females; mean age: 43.7 years; range: 19-76 years) evaluated for clinical suspicion of brachial plexopathy, undergoing brachial plexus MRI (10 left, 9 right, 5 bilateral, 29 total scans analyzed). Agar phantoms mimicking nerve and muscle were also evaluated. FIELD STRENGTH/SEQUENCE: 3-Tesla, 3D STIR-TSE with and without VERSE. ASSESSMENT: Three radiologists, blinded to the sequence type and clinical data, qualitatively evaluated nerve conspicuity, motion, and preferred sequence on a 5-point scale. STATISTICAL TESTS: Wilcoxon signed-rank tests compared nerve conspicuity (0-4 scale), motion artifact (0-4 scale), and preferred series between the non-VERSE and VERSE pulse sequences. Gwet's AC2 assessed inter-rater agreement. A p-value < 0.05 was considered statistically significant. RESULTS: The VERSE STIR-TSE sequence was significantly preferred by all raters. Motion artifact was not significantly different between the sequences (p = 0.11). Conspicuity of the suprascapular nerve was significantly greater with VERSE for both its proximal segments (median: 3, interquartile range: (2, 4), vs. 3 (1, 4)) and distal segments (4 (2, 4) vs. 3 (2, 4)), but conspicuity of the axillary nerve was not significantly different between the sequences (p = 0.27-0.61). Phantom scans confirmed a 74% and 49% increase in signal with VERSE in the muscle and nerve-mimicking phantoms, respectively. DATA CONCLUSION: STIR-TSE with VERSE provided overall superior image quality for brachial plexus MRN as compared to conventional STIR-TSE. EVIDENCE LEVEL: 2. TECHNICAL LEVEL: 1.
With global population aging and increased life expectancy, bone diseases affect a substantial proportion of individuals worldwide, imposing a significant socioeconomic burden. Although X-ray-based imaging techniques rem...With global population aging and increased life expectancy, bone diseases affect a substantial proportion of individuals worldwide, imposing a significant socioeconomic burden. Although X-ray-based imaging techniques remain the clinical standard for bone assessment, they are constrained by ionizing radiation exposure and poor soft-tissue contrast. Magnetic resonance imaging (MRI) has emerged as a promising radiation-free alternative, enabling detailed evaluation of tissue properties, bone microstructure, functional status, and pathological changes. However, the intrinsically low proton density and rapid transverse relaxation of bone tissue present fundamental technical challenges. Over the past decades, numerous MRI-based techniques have been developed to address these limitations. Yet, the literature remains fragmented. This review synthesizes recent advancements in bone MRI, covering conventional sequences (e.g., T1-weighted and T2-weighted imaging), advanced sequences (e.g., ultrashort echo time and zero echo time), metabolic imaging sequences (e.g., magnetic resonance spectroscopy and dynamic contrast-enhanced MRI), and hardware innovations (e.g., ultra-high-field MRI at 7/14 T). The strengths and limitations of these techniques are discussed, and their roles are highlighted in early diagnosis, therapeutic monitoring, and management of diverse bone disorders, including osteoporosis, osteoarthritis, osteosarcoma, and osteonecrosis. Furthermore, we explore how artificial intelligence, particularly deep learning models, enhances MRI capabilities by reducing scanning time, adding synthetic contrasts like synthetic CT, improving image quality, and increasing diagnostic accuracy. Finally, we outline challenges and future directions to advance bone assessment. This comprehensive review may guide preclinical research and accelerate clinical translation of bone MRI techniques, ultimately improving musculoskeletal disease management. LEVEL OF EVIDENCE: 4. TECHNICAL EFFICACY: Stage 2.
BACKGROUND: Habitat imaging has been widely used to assess tumor treatment response; however, the role of MRI-based habitat analysis in identifying pathological complete response (pCR) after neoadjuvant chemotherapy (NAC...BACKGROUND: Habitat imaging has been widely used to assess tumor treatment response; however, the role of MRI-based habitat analysis in identifying pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer remains an unresolved issue. OBJECTIVES: To evaluate the utility of dynamic contrast-enhanced MRI (DCE-MRI)-based habitat imaging in identifying pCR after NAC in breast cancer patients. STUDY TYPE: Retrospective. FIELD STRENGTH/SEQUENCE: 1.5 T or 3.0 T, DCE-MRI (Gradient echo). SUBJECTS: Three hundred and sixty-three women with biopsy-confirmed breast cancer from Center A (n = 249, training set) and Center B and Center C (n = 114, external validation set). ASSESSMENT: DCE-MRI peak-enhancement images were used to generate habitat maps via supervoxel segmentation and K-means clustering. Two intratumoral heterogeneity (ITH) metrics (Volume Entropy and Intensity Entropy) were extracted to quantify the structural and signal complexity of tumors. Three discriminative models were developed: a clinical model based on clinicopathologic variables, an ITH model incorporating Volume Entropy and Intensity Entropy, and an integrated nomogram combining both feature sets. STATISTICAL TESTS: Student's t test, Wilcoxon U test, χ , Fisher exact test, and receiver operating characteristic curve analysis. Significance was set at p < 0.05. RESULTS: Volume Entropy and Intensity Entropy were significantly lower in pCR versus non-pCR groups. HR status, HER2 status, and both ITH features were independent indicators of pCR. The nomogram showed superior performance (AUC = 0.849 in the training set and 0.825 in the validation set), outperforming the clinical model (DeLong test). Subgroup analysis across four molecular subtypes showed AUCs ranging from 0.762 to 0.890. An interactive online tool was developed for clinical application. DATA CONCLUSION: MRI-based habitat analysis offers a simple, interpretable, and clinically applicable approach for noninvasive identification of pCR to NAC in breast cancer. TECHNICAL EFFICACY: Stage 3.
BACKGROUND: The role of ferroptosis in Cardiac arrest (CA)-induced cerebral edema remains unclear. PURPOSE: To investigate whether ferroptosis contributes to blood-brain barrier (BBB) disruption and aquaporin-4 (AQP4) dy...BACKGROUND: The role of ferroptosis in Cardiac arrest (CA)-induced cerebral edema remains unclear. PURPOSE: To investigate whether ferroptosis contributes to blood-brain barrier (BBB) disruption and aquaporin-4 (AQP4) dysfunction following CA. STUDY TYPE: Prospective. ANIMAL MODEL: Asphyxia-induced CA rat model. Forty two rats were used and assigned to the CA (24) and the sham (18) group. FIELD STRENGTH/SEQUENCE: T2-weighted anatomical imaging with 2D turbo spin-echo sequence, QSM with 3D GRE sequence, IVIM with 2D RESOLVE EPI sequence, H-MRS with SVS-PRESS sequence. ASSESSMENT: Multiparametric MRI was performed 24 h after return of spontaneous circulation (ROSC). Imaging findings were validated using histology, immunohistochemistry, Western blot, and transmission electron microscopy. STATISTICAL TESTS: Unpaired two-tailed Student's T-test was used. A p value less than 0.05 was considered statistically significant. RESULTS: CA led to marked neurological deficits, although no obvious abnormalities were observed on T-weighted MRI. QSM revealed marked iron accumulation in the hippocampus, which was associated with elevated ROS, lipid peroxidation, and altered expression of ferroptosis-related markers (downregulation of GPX4 and upregulation of ACSL4). Electron microscopy confirmed mitochondrial changes characteristic of ferroptosis. Ferroptosis-induced lipid peroxidation resulted in degradation of tight-junction proteins (ZO-1 and occludin), BBB leakage (elevated serum S100β), and loss of AQP4 polarity. IVIM showed a selective reduction in true tissue diffusivity (IVIM D), indicating cytotoxic edema. H-MRS revealed decreased N-acetylaspartate, increased lipid peaks, and reduced myo-inositol levels, consistent with neuronal death and astrocytic swelling. DATA CONCLUSION: This study provides evidence for a sequential cascade after CA and ROSC in which iron overload is associated with ferroptosis, which is linked to disruption of the blood-brain barrier. This barrier disruption coincides with AQP4 depolarization, inducing cytotoxic and vasogenic edema, which, along with depolarization, is accompanied by neuronal death. Multimodal MRI noninvasively captures this process, offering an early detection and monitoring platform for ferroptosis-related brain injury and underscoring its potential as a translational tool for neuroprotective interventions. EVIDENCE LEVEL: 1. TECHNICAL EFFICACY: Stage 1.