Purpose: To evaluate the clinical utility of macromolecular proton fraction mapping for early osteoarthritis detection and compare its effectiveness with T₂* mapping in evaluating cartilage degeneration.

Methods: Eleven controls and 29 patients with osteoarthritis underwent 3.0T magnetic resonance imaging. Patients were classified based on the Kellgren–Lawrence grading system into mild osteoarthritis (KL 1–2, n = 9) and severe (KL 3–4, n = 20) osteoarthritis. Macromolecular proton fraction maps were generated from proton density-, T₁-, and magnetization transfer-weighted images using a single-point synthetic reference algorithm. T₂* maps were derived from multi-echo sequences. Macromolecular proton fractions and T₂* values were measured in 6 subregions of the femoral cartilage. Statistical analyses were conducted to compare values among the control, mild osteoarthritis, and severe osteoarthritis groups.

Results: Macromolecular proton fraction values decreased with increasing osteoarthritis severity. Compared to controls, both the mild and severe osteoarthritis groups exhibited significantly lower macromolecular proton fraction in the medial anterior and medial posterior regions. Additionally, the severe osteoarthritis group demonstrated significantly lower macromolecular proton fraction values in the medial central and lateral posterior regions compared to controls. In contrast, T₂* values generally increased with osteoarthritis severity. The mild and severe osteoarthritis groups had significantly elevated T₂* values in the medial anterior region compared to controls. Furthermore, the mild osteoarthritis group exhibited increased T₂* in the medial central region, whereas the severe osteoarthritis group had significantly higher T₂* in the medial anterior, medial posterior, and lateral posterior regions compared to controls.

Conclusion: Macromolecular proton fraction mapping demonstrated sensitivity to early-stage cartilage degeneration in osteoarthritis, suggesting its potential as a biomarker for early osteoarthritis detection. The combination of macromolecular proton fraction and T₂* mapping could enhance the biochemical assessment of cartilage integrity, providing valuable insights for early diagnosis and monitoring treatment effects in osteoarthritis.

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The interpretation of abdominal diffusion images remains difficult because different types of tissue coexist within each voxel. In this study, we estimated the distribution of the diffusion coefficient (D) within each voxel using non-negative least squares from diffusion-weighted images with multiple b-values. Additionally, a method for visualizing the results as a set of images representing the D ranges was developed. This method was tested on healthy volunteers.

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Purpose: To investigate the relationship between the signal intensity (SI) of the entire labyrinthine fluid on non–contrast-enhanced 3D real inversion recovery (3D–real IR) imaging and the endolymphatic volume measured on contrast-enhanced HYDROPS-Mi2 (HYbriD of Reversed image Of Positive endolymph signal and native image of positive perilymph Signal image Multiplied with hT2w MR cisternography) imaging.

Methods: This retrospective study included 37 patients (74 ears) with suspected endolymphatic hydrops (EH). The volume ratio of the endolymphatic space (%EL_vol) was measured on contrast-enhanced HYDROPS-Mi2 images, and the normalized volume-averaged signal intensity (nSI_vol) of the entire labyrinthine fluid was measured on non–contrast-enhanced 3D–real IR images. Statistical analyses included comparisons of nSI_vol between the cochlea and vestibule, side-to-side differences in EH-negative ears, paired comparisons of nSI_vol between larger- and smaller-%EL_vol sides, correlations between %EL_vol and nSI_vol, and receiver operating characteristic (ROC) curve analysis of nSI_vol for discriminating severe from mild/no EH. The presence of EH was defined based on the clinical diagnosis using Nakashima grading.

Results: The vestibular %EL_vol was significantly higher and the vestibular nSI_vol significantly lower than that in the cochlea (both P < 0.001). In EH-negative ears, no significant side-to-side difference in nSI_vol was observed. In both cochleae and vestibules, nSI_vol was significantly lower on the larger-%EL_vol side than on the smaller-%EL_vol side (cochlea: P = 0.002; vestibule: P = 0.007). Significant negative correlations between %EL_vol and nSI_vol were observed in both the cochlea (Spearman’s rank correlation coefficient [R_s] = –0.598, P < 0.001) and vestibule (R_s = –0.417, P < 0.001). The area under the ROC curve was 0.827 in the cochlea, and 0.698 in the vestibule.

Conclusion: The SI of the entire labyrinthine fluid measured on non–contrast-enhanced 3D–real IR imaging showed a significant negative correlation with the endolymphatic volume measured on contrast-enhanced HYDROPS-Mi2. These findings suggest that the SI of labyrinthine fluid, as measured on non–contrast-enhanced 3D–real IR images, may serve as an indirect indicator for estimating the degree of EH.

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Purpose: This study aimed to evaluate the diagnostic potential of macromolecular proton fraction (MPF) mapping combined with magnetic susceptibility measurements as subcortical biomarkers in Parkinson’s disease (PD).

Methods: Twenty patients with PD and 9 age-matched healthy controls underwent 3.0T magnetic resonance imaging, including MPF mapping and quantitative susceptibility mapping (QSM). MPF and magnetic susceptibility values of the 16 subcortical nuclei were measured in both the PD group and healthy control group, and these values were compared between the 2 groups. Diagnostic performance of MPF and magnetic susceptibility in the subcortical nuclei was individually evaluated using receiver operating characteristic (ROC) analysis. A logistic regression model was developed for the diagnosis of PD using a combination of MPF and magnetic susceptibility values.

Results: Quantitative analyses revealed significantly reduced MPF values (false discovery rate–corrected P < 0.05) in 7 subcortical nuclei in the PD group, namely the hypothalamus, parabrachial pigmented nucleus, red nucleus, substantia nigra pars reticulata, substantia nigra pars compacta, ventral pallidum, and ventral tegmental area. Additionally, magnetic susceptibility was significantly elevated (false discovery rate–corrected P < 0.05) in the parabrachial pigmented nucleus and substantia nigra pars compacta. ROC curve analysis demonstrated strong diagnostic performance, with the ventral pallidum showing the highest MPF-based diagnostic accuracy (area under the curve [AUC] = 0.82) and the substantia nigra pars compacta showing the highest QSM-based accuracy (AUC = 0.88). The logistic regression model combining MPF and magnetic susceptibility showed the best performance (AUC = 0.93).

Conclusion: MPF mapping, particularly when combined with magnetic susceptibility measurements, may serve as a quantitative diagnostic biomarker for PD, and the observed widespread alterations across multiple subcortical nuclei provide new insights into the pathology of PD beyond the classic nigrostriatal pathway.

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Purpose: To identify the imaging characteristics of rare, histopathologically confirmed focal nodular hyperplasia (FNH) and FNH-like lesions (FNH/FNH-like lesions) and determine whether invasive procedures could have been avoided by comprehensive MRI review.

Methods: We retrospectively enrolled patients with pathologically confirmed FNH/FNH-like lesions between January 2011 and December 2023. These cases underwent biopsy or resection due to their atypical hepatobiliary phase appearance. Six patients with hepatocellular carcinoma (HCC) were included from a separate cohort for comparison. Gadoxetic acid-enhanced MRI findings were qualitatively evaluated. Apparent diffusion coefficient (ADC) values and enhancement during the hepatobiliary phase were quantitatively assessed, and the relative enhancement ratio (RER) to liver parenchyma and intrahepatic vessel (RERv) was calculated. Organic anion transporting polypeptides (OATP)1B3 expression was confirmed histopathologically.

Results: Five patients with FNH/FNH-like lesions and 6 patients with HCC were evaluated. The non-contrast MRI findings were non-specific for both groups. All 5 FNH/FNH-like lesions displayed non-rim arterial phase hyperenhancement (APHE) without washout during dynamic contrast study with ADC values of 1.162 ± 0.124 × 10⁻³mm²/sec (mean ± standard deviation). Whereas all 6 HCCs displayed non-rim APHE and washout with ADC values of 0.923 ± 0.138 × 10⁻³mm²/sec. During the hepatobiliary phase, all 5 FNH/FNH-like lesions were hypointense to the liver but hyperintense to intrahepatic vessels, with RER and RERv ≥ 0.90, indicating preserved gadoxetic acid uptake. OATP1B3 membrane expression was confirmed. By contrast, 5 HCCs were hypointense to both the liver and vessels, with RER and RERv < 0.90 and no OATP1B3 expression.

Conclusion: FNH/FNH-like lesions with hepatobiliary phase hypointensity, the characteristic finding of hyperintensity relative to intrahepatic vessels distinguished them from similarly presenting HCCs. Careful evaluation of this specific imaging feature might have potentially avoided the need for invasive treatment or biopsy in these diagnostically challenging cases.

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Purpose: Although automation offers several benefits in MRI-guided abdominal biopsies, the conventional surgeon-centric approach continues to be the preferred technique. This study presents an ergonomic biopsy device aimed at streamlining the MRI-guided abdominal biopsy process while preserving operator control.

Methods: A dedicated belt was designed with adjustable straps to accommodate patients of varying sizes. A biopsy frame with 2 manual degrees of freedom was movably affixed to the belt, allowing for adjustable positioning across the patient’s circumference to align with the region of interest. Preliminary testing was performed on an abdominal biopsy phantom with 2 embedded 7-mm tumor mimics in a 3T MRI scanner. Needle guide registration in MRI coordinates was achieved by attaching a water-filled syringe to the guide, which was then navigated to align with each target using a straightforward method involving the acquisition and fusion of parallel images. A clinically relevant half-Fourier acquisition single-shot turbo spin echo sequence was used for both the initial alignment and for intermittent imaging during the stepwise advancement of a metallic clinical needle toward the target.

Results: The device was easy to use, even for a non-experienced operator. The employed methodology enabled straightforward calculation of the 2D path for aligning the syringe with the target. Alignment accuracy was within the submillimeter range. The employed sequence was robust against susceptibility artifacts, enabling precise guidance, with the accuracy of tumor puncture ultimately dependent on the operator.

Conclusion: The proposed biopsy method has the potential to enhance stability and accuracy over traditional techniques, while being more ergonomic and cost-effective than advanced robotic systems, also maintaining human control. Extensive preclinical and clinical evaluation is needed to fully assess effectiveness and safety.

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Purpose: MRI findings of high-grade serous carcinoma (HGSC) with and without homologous recombination deficiency (HRD) were compared to explore the feasibility of using MRI as a genetic predictor.
Methods: We retrospectively reviewed MRI data from HRD-positive and HRD-negative HGSC and evaluated tumor size, appearance, apparent diffusion coefficient (ADC), time-intensity curve, and several dynamic contrast-enhanced curve descriptors. Age, primary site, tumor stage, bilaterality, presence of lymph node metastasis, presence of peritoneal metastasis, and tumor marker levels were also compared.
Results: Forty-eight patients with HRD-positive HGSC (17 patients with BRCA1 variant, 9 patients with BRCA2 variant, and 22 without BRCA variants) and 18 patients with HRD-negative HGSC were included. The HRD-negative patients’ mean age was 67 years, which was significantly higher than that of the HRDpositive patients (60 years, P = 0.011). High-risk time-intensity curve (TIC) patterns were more common in HRD-negative tumors (94%) than in HRD-positive tumors (63%; P = 0.047). Tumors without HRD exhibited significantly higher wash-in rates (P = 0.023). Additionally, unresectable lymph node metastases were significantly more frequent in HRD-negative patients (P = 0.013). No significant differences were observed in the other evaluated factors.
Conclusion: The comparison between HGSC with and without HRD revealed that HGSC without HRD was significantly associated with older age, a higher likelihood of exhibiting a high-risk TIC pattern, a higher wash-in rate, and a higher frequency of unresectable lymph node metastasis.

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Purpose: The ocular and brain glymphatic systems may share common physiological pathways. We hypothesized that the anteroposterior movement of gadolinium-based contrast agent (GBCA) that has leaked into the vitreous could serve as a biomarker for brain glymphatic function. This study aimed to retrospectively investigate the association between the intravitreal GBCA distribution on MRI and recently proposed imaging markers of impaired brain waste clearance.
Methods: We analyzed 156 eyes from 78 adult participants who underwent 3T MRI 4 hr after standard-dose GBCA administration. On 3D-real IR images, we calculated a “contrast shift index” (the signal difference between anterior and posterior vitreous volumes of interest: VOIa-VOIp) to quantify the anteroposterior GBCA distribution. The primary outcome was a composite endpoint of positivity for either putative meningeal lymphatics at the posterior sigmoid sinus (PML-PSS) or enhanced basal ganglia perivascular spaces (PVS-BG). Multivariable logistic regression with cluster-robust inference was used to assess predictors, including the contrast shift index, mean vitreous contrast distribution, age, sex, and axial length of the eye.
Results: A positive contrast shift index, indicating preferential anterior GBCA distribution, was significantly and independently associated with the composite outcome of impaired brain clearance (P = 0.006). Age (P <0.001) and male sex (P = 0.009) were also independent predictors. A predictive model incorporating these factors demonstrated high discrimination, with an area under the receiver operating characteristic curve (AUC) of 0.872. Axial length of the eye and mean vitreous contrast distribution were not significant independent predictors.
Conclusion: The anteroposterior distribution of GBCA in the vitreous is a novel, non-invasive imaging biomarker associated with impaired brain clearance function. This “contrast shift index” may reflect systemic glymphatic dysregulation common to both the eye and brain, offering a new avenue for assessing neurodegenerative risk.

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Purpose: The ability to accurately detect and characterize intramammary micro- and macrocalcifications without ionized radiation has significant clinical implications for early breast cancer assessment. The aim of this prospective study was to investigate the feasibility of detecting intramammary calcifications using 3D multi-echo gradient echo (ME-GRE) magnitude and true susceptibility-weighted images (tSWI) compared to digital mammography (DM) in patients with different breast sizes and densities of breast parenchyma at 1.5T.

Methods: Two board-certified radiologists evaluated digital mammograms of 70 patients and compared them to the corresponding SW-based images concerning detection of intramammary calcifications and determination of their sizes. The clinical performance of both SW-based techniques in accurately detecting and assessing intramammary calcifications was determined. In addition an interobserver agreement was performed.

Results: Compared to DM, visualization of calcification lesions using both SW-based techniques is influenced by: 1) Morphology (shape and homogeneity) of calcifications; 2) Spatial arrangement of calcifications. Closely adjacent calcifications may not be distinguishable in the SW-based images as individual lesions. Overlapping susceptibility effects resulted in a single, larger lesion; 3) The (in-phase or out-of-phase cycle) echo time value selected in the imaging protocol plays a crucial role in visualizing the lesions; and 4) Lesion size was overestimated by up to 2.0 mm when comparing SW-based techniques to DM. An almost perfect interobserver agreement was found for the analysis. Microcalcifications could not be visualized. A sensitivity of 13.0% and specificity of 99.7% for the diagnosis of macrocalcifications could be provided with both SW-based techniques.

Conclusion: Our findings highlight the potentials and limitations of SW-based techniques at 1.5 T for characterizing intramammary micro- and macrocalcifications. The high specificity of SW-based techniques in combination with higher magnetic field strengths could revolutionize breast cancer screening and management.

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Purpose: This study aims to extend the general kinetic model (GKM) for perfusion signal analysis using multi-pulsed arterial spin labeling (mPASL) acquisitions with multiple post-labeling delays (mPLD). The approach aims to improve accuracy and gain potential for broader experimental and clinical applications.

Methods: The magnetization vector evolution of the mPASL technique was analyzed using sequence diagrams and numerical simulation, supplemented by static phantom experiments. The GKM was adapted to support different configurations of mPASL tagging pulses in “dark” and “bright” methods. The proposed approach was validated on a constant-flow phantom and applied to in-vivo foot perfusion measurements in a cohort of 5 healthy subjects.

Results: Simulations showed that the ratio between “dark” and “bright” mPASL methods is determined by fluid T₁ relaxation time, the number of selective pulses, and labeling efficiency. Experiments with a constant-flow phantom demonstrated that GKM with mPASL enables semi-quantitative perfusion analysis, providing high-temporal-resolution perfusion curves. Estimated perfusion coefficients of constant flow phantom were consistent across acquisitions (5.1% variation), confirming the robustness of the GKM extension for mPASL with multiple post-labeling delays. However, in-vivo results deviated from simulation and constant flow experiments, highlighting potential physiological complexities, and model limitations.

Conclusion: Extending the GKM to mPASL acquisitions demonstrates reliable performance under controlled constant flow conditions. Phantom experiments confirmed the accuracy of the approach, while in-vivo measurements in feet revealed deviations from simulation and constant flow results, suggesting the need to account for physiological factors and potential model extension due to pulsatile flow.

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This case report shows that paramagnetic rim lesions (PRLs), markers of chronic active lesions in multiple sclerosis, vary in visibility depending on scan-parameters of susceptibility-weighted imaging (SWI). Routine SWI for microbleed detection with low flip angle (FA) failed to depict PRLs, while longer TE and higher FA improved visibility. Phase images consistently visualized PRLs. These findings underscore the need to optimize TE and FA, as suboptimal SWI settings may hinder PRL detection.

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Purpose: To evaluate the efficacy of radiomic analysis applied to pretreatment gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI (Gd-EOB-DTPA-MRI) for predicting the response to transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma.

Methods: Data and images from 40 consecutive patients (28 men, 12 women) who underwent pretreatment Gd-EOB-DTPA-MRI and a total of 52 TACE procedures for 75 non-treated hepatocellular carcinomas were retrospectively analyzed. Two radiologists manually outlined lesions on pretreatment arterial- and hepatobiliary-phase hepatic images to extract radiomic features. The radiomics data from one observer were randomly divided into a training dataset and a validation dataset in the ratio of 7:3. Radiomic features extracted using least absolute shrinkage and selection operator (LASSO) binomial regression applied to the training dataset and that showed intraclass correlation coefficients (ICC) >0.7 were used to construct a radiomic model. The predictive performance of the model was evaluated using receiver operating characteristics curves. Lesions classified as showing a complete or partial response according to the modified RECIST criteria were allocated to a response group.

Results: There was no significant difference in Child–Pugh score, tumor marker values, or TACE procedure between response and non-response groups. Six radiomic features were selected using the LASSO binomial regression and 5 of them showing an ICC >0.7 were used to establish the radiomic model. The area under the curve of the radiomic model was 0.89 for the training dataset, 0.83 for the validation dataset, and 0.83 for the other observer’s data. The sensitivity and specificity for the prediction of tumor response to TACE were 78% and 92% for the training dataset; 71% and 50% for the validation dataset; and 75% and 79% for the other observer’s data.

Conclusion: The pretreatment Gd-EOB-DTPA-MRI-based radiomic model is useful for predicting the response to TACE of hepatocellular carcinoma.

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Purpose: Among patients with hepatitis B virus-associated liver cirrhosis (HBV-LC), there may be differences in the hepatic parenchyma between those with and without hepatocellular carcinoma (HCC). Proton MR spectroscopy (¹H-MRS) is a well-established tool for noninvasive metabolomics, but has been challenging in the liver allowing only a few metabolites to be detected other than lipids. This study aims to explore the potential of ¹H-MRS of the liver in conjunction with deep learning to differentiate between HBV-LC patients with and without HCC.

Methods: Between August 2018 and March 2021, ¹H-MRS data were collected from 37 HBV-LC patients who underwent MRI for HCC surveillance, without HCC (HBV-LC group, n = 20) and with HCC (HBV-LC-HCC group, n = 17). Based on a priori knowledge from the first 10 patients from each group, big spectral datasets were simulated to develop 2 kinds of convolutional neural networks (CNNs): CNNs quantifying 15 metabolites and 5 lipid resonances (qCNNs) and CNNs classifying patients into HBV-LC and HBV-LC-HCC (cCNNs). The performance of the cCNNs was assessed using the remaining patients in the 2 groups (10 HBV-LC and 7 HBV-LC-HCC patients).

Results: Using a simulated dataset, the quantitative errors with the qCNNs were significantly lower than those with a conventional nonlinear-least-squares-fitting method for all metabolites and lipids (P ≤0.004). The cCNNs exhibited sensitivity, specificity, and accuracy of 100% (7/7), 90% (9/10), and 94% (16/17), respectively, for identifying the HBV-LC-HCC group.

Conclusion: Deep-learning-aided ¹H-MRS with data augmentation by spectral simulation may have potential in differentiating between HBV-LC patients with and without HCC.

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Purpose: Acupuncture is believed to significantly modify neural circuits in the brain. However, the effects of moxibustion stimulation remain unclear. Therefore, we used functional MRI to investigate brain activation sites induced by moxibustion stimulation using an electric moxibustion device that mimics Japanese Tonetsu-kyu half-grain-sized direct moxibustion.

Methods: Twenty-two healthy adult participants underwent 6 rounds of 7-s moxibustion stimulations on the right acupuncture point ST36 using electric moxibustion during functional MRI measurement. The maximum output temperature of electric moxibustion was 67.5°C. However, the contact surface temperature was adjusted to 58.6 ± 0.1°C using cooking wrap to avoid small burns caused by heating. The ON time was divided into 3 periods: ON1, 2s from the start of moxibustion stimulation (<45°C); ON2, 5s from 2s after the start of output to the end of stimulation (>45°C); and ON3, 3s after the completion of stimulation. Each block was designed with all options other than ON set to OFF.

Results: Common and different activations were observed in all ON times. During stimulation, common activation was observed in the insula, S1, and supramarginal gyrus. Activation in the central operculum, frontal operculum and supplementary motor area was observed only in the ON1 condition, while activation in the frontal pole, cerebellum, and right S2 was observed only in the ON2 condition. Using electric moxibustion that mimics a grain-sized direct moxa cone, common and different activations were confirmed from the start of output to 45°C and above 45°C, and the activation was sustained after the completion of stimulation.

Conclusion: This study showed that moxibustion could affect almost the same areas of pain-related regions. Based on the findings of this study, further research on moxibustion-induced brain activation may help elucidate the mechanism of its therapeutic effects.

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Purpose: To evaluate short T₂ components potentially reflecting calcification or other susceptibility-affected tissue components in atherosclerotic plaques, using multicomponent analysis with ultrashort TE (UTE) MRI.

Methods: A phantom experiment was conducted using a 4-echo UTE sequence, mimicking the sample as a small amount of calcification found intra-voxel. The phantom included 6 samples containing varying concentrations of hydroxyapatite (calcification) and mayonnaise (lipid–water emulsion). Data acquired from the UTE sequence were compared with those obtained using a conventional multi-echo gradient-echo (mGRE) method.

Results: Bi-exponential analysis of UTE data successfully separated short- and long-T₂* components, with ranges of 0.44–4.81 ms and 4.29–24.37 ms, respectively. Short T₂* values derived from UTE showed minor changes with increasing hydroxyapatite concentration. Using bi-exponential analysis of mGRE data, short and long T₂* values ranged from 0.17–0.77 ms and 6.16–39.20 ms, respectively. For mono-exponential fitting of mGRE data, T₂* values ranged from 4.84–38.32 ms. In all datasets, 1/T₂* increased with hydroxyapatite concentration. The signal fraction of short T₂* components in the UTE dataset decreased as hydroxyapatite concentration increased. A clinical scan of 1 patient with an atherosclerotic plaque yielded mean short and long T₂* values of 0.12 ± 0.35 ms and 33.22 ± 17.25 ms, respectively.

Conclusion: T₂* analysis using UTE data enabled the separation of mixed calcification and mayonnaise (lipid–water emulsion) within a sample into 2 components and detected short T₂* components that may reflect calcification-related susceptibility effects, without directly indicating calcification. Multicomponent T₂* analysis with UTE-MRI is a promising technique for evaluating calcification and other short T₂* components in atherosclerotic plaques.

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This study presents a novel data augmentation approach to improve deep learning (DL)-based segmentation for 3D phase-contrast magnetic resonance angiography (PC-MRA) images affected by pulsation artifacts. Augmentation was achieved by simulating pulsation artifacts through the addition of periodic errors in k-space magnitude. The approach was evaluated on PC-MRA datasets from 16 volunteers, comparing DL segmentation with and without pulsation artifact augmentation to a level-set algorithm. Results demonstrate that DL methods significantly outperform the level-set approach and that pulsation artifact augmentation further improves segmentation accuracy, especially for images with lower velocity encoding. Quantitative analysis using Dice-Sørensen coefficient, Intersection over Union, and Average Symmetric Surface Distance metrics confirms the effectiveness of the proposed method. This technique shows promise for enhancing vascular segmentation in various anatomical regions affected by pulsation artifacts, potentially improving clinical applications of PC-MRA.

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Purpose: To evaluate the feasibility of high-spatial-resolution hepatobiliary phase (HBP) imaging using optimized integrated combination with the compressed sensing and parallel imaging technique (Compressed SENSE).

Methods: Sixty consecutive participants underwent liver MRI and breath-hold HBP imaging using enhanced T1 high-resolution isotropic volume excitation (eTHRIVE; SENSE factor, 1.7; slice thickness/gap, 4/-2 mm; and acquisition time, 20s), eTHRIVE with Compressed SENSE (CS-eTHRIVE_4mm; C SENSE factor, 3.45; slice thickness/gap, 4/-2 mm; and acquisition time, 10s), and thin-slice eTHRIVE with Compressed SENSE (CS-eTHRIVE_2mm; C SENSE factor, 3.45; slice thickness/gap, 2/0 mm; and acquisition time, 20s). The signal intensity ratio (SIR) and signal-to-noise ratio (SNR) of the liver on each HBP image were calculated. The image quality and conspicuity of hypointense nodules on HBP images were qualitatively assessed. Then, the sensitivity for detecting hypointense nodules was calculated. The quantitative and qualitative parameters of three HBP images were compared.

Results: The SIR of the three HBP images did not differ (P = 0.36). The SNR of CS-eTHRIVE_2mm was lower than that of eTHRIVE and CS-eTHRIVE_4mm (P < 0.001). CS-eTHRIVE_2mm had a better image quality than eTHRIVE and CS-eTHRIVE_4mm (P < 0.001). CS-eTHRIVE_2mm (97.5%) had a significantly better sensitivity for detecting hypointense nodules on HBP image than eTHRIVE (86.4%) and CS-eTHRIVE_4mm (89.0%) (P = 0.001‒0.006).

Conclusion: CS-eTHRIVE_2mm had an excellent image quality and lesion detectability due to its high-spatial-resolution.

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Purpose: This study aimed to compare the differences in the imaging findings for dedifferentiated liposarcoma (DDLS) and myxoid liposarcoma (MLS).

Methods: The study included 30 patients with histopathologically confirmed DDLS and 13 patients with MLS. All DDLSs and MLSs were diagnosed immunohistochemically using MDM2 and DDIT3 staining, respectively. Conventional MRI, CT, and ¹⁸F-fluorodeoxyglucose-positron emission tomography/CT findings were retrospectively evaluated and compared between the 2 pathologies.

Results: The median age of patients with DDLS was higher than that of patients with MLS (74 vs. 46 years, P < 0.01). In 10 DDLSs and 7 MLSs with fatty areas, the well-differentiated liposarcoma-like fatty areas were more common in DDLS than in MLS (70% vs. 14%), whereas septal/linear fatty areas were less common in DDLS than in MLS (30% vs. 86%, P < 0.05). The T2-hyperintense area of non-fatty area was less common in DDLS than in MLS (50% vs. 92%, P < 0.05), and the tumor-to-muscle signal intensity ratio of non-fatty areas on T2-weighted images was lower in DDLS than in MLS (3.18 vs. 5.92, P < 0.01). Apparent diffusion coefficient value was lower in DDLS than in MLS (1.29 vs. 2.10 × 10⁻³mm²/sec, P < 0.01). Unenhanced CT attenuation of non-fatty area was greater in DDLS than in MLS (33 vs. 19 Hounsfield unit, P < 0.01).

Conclusion: MRI features are valuable in differentiating MLS from DDLS. Younger age, septal/linear fatty areas, and high signal intensity of non-fatty areas on T2-weighted images were useful for diagnosing MLS.

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Purpose: Pulmonary valve regurgitation after repaired Tetralogy of Fallot (TOF) or double-outlet right ventricle (DORV) causes hypertrophy and papillary muscle enlargement. Cardiac magnetic resonance imaging (CMR) can evaluate the right ventricular (RV) dilatation, but the effect of trabecular and papillary muscle (TPM) exclusion on RV volume for TOF or DORV reoperation decision is unclear.

Methods: Twenty-three patients with repaired TOF or DORV, and 19 healthy controls aged ≥15, underwent CMR from 2012 to 2022. TPM volume is measured by artificial intelligence. Reoperation was considered when RV end-diastolic volume index (RVEDVI) >150 mL/m² or RV end-systolic volume index (RVESVI) >80 mL/m².

Results: RV volumes were higher in the disease group than controls (P α 0.001). RV mass and TPM volumes were higher in the disease group (P α 0.001). The reduction rate of RV volumes due to the exclusion of TPM volume was 6.3% (2.1–10.5), 11.7% (6.9–13.8), and 13.9% (9.5–19.4) in the control, volume load, and volume α pressure load groups, respectively. TPM/RV volumes were higher in the volume α pressure load group (control: 0.07 g/mL, volume: 0.14 g/mL, volume α pressure: 0.17 g/mL), and correlated with QRS duration (R α 0.77). In 3 patients in the volume α pressure, RV volume included TPM was indicated for reoperation, but when RV volume was reduced by TPM removal, reoperation was no indicated.

Conclusion: RV volume measurements, including TPM in volume α pressure load, may help determine appropriate volume recommendations for reoperation.

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Purpose: To study the potential advantages of phosphorus magnetic resonance spectroscopy (³¹P-MRS) in differentiating advanced from mild fibrosis in non-alcoholic fatty liver disease (NAFLD) and early diagnosis at high field strength MR (9.4 Tesla).

Methods: Fibrosis of normal and carbon tetrachloride (CCl₄)-treated male rats was staged into: none (F0), perisinusoidal or periportal (F1), perisinusoidal and portal/periportal (F2), bridging fibrosis (F3) and cirrhosis (F4) by Sirius Red staining. The degree of steatosis and inflammatory activity were also graded based on Hematoxylin and Eosin staining. Rats were divided into different groups by different stages of fibrosis (F0, F1–2, F3–4) and laboratory blood tests were performed to verify the degree of liver injury. ³¹P-MRS was performed at 9.4T MR to obtain signal peaks of different phosphorus metabolites and the changes of the ratios between the peaks were observed.

Results: At 9.4 T, phosphoethanolamine (PE), phosphocholine (PC) and glycerophosphorylethanolamine (GPE), glycerophosphorylcholine (GPC) could be separated respectively from the peaks of phosphomonoesters (PME) and phosphodiesters (PDE), meanwhile nicotinamide adenine dinucleotide phosphate (NADPH) and uridine diphosphate glucose (UDPG) showed up as well. The marker of cell membrane metabolism, in F1–2, PME/PDE (P < 0.001), PC/GPE (P < 0.01), PC/GPC (P < 0.05) and PC/(PME + PDE) (P < 0.05) decreased while GPE/(PME + PDE) (P < 0.05) and GPC/(PME + PDE) (P < 0.05) increased significantly. In F3–4, there was a recovery trend of most ratios, especially for PC/(PME + PDE) (P < 0.05). As for the main ratio related to energy metabolism, β-ATP/P_total (P < 0.05) decreased in the early stage of the disease (F1–2) and this decline was maintained in advanced stage (F3–4). NADPH/P_total (P < 0.01) and β-ATP/Pi (inorganic phosphate) (P < 0.05) ratio was lower in F3–4 comparing with F0.

Conclusion: ³¹P-MRS can generally stage the liver fibrosis by comparing the ratios of the phosphorus metabolites resonance peaks at 9.4 T and more importantly it can be used for early diagnosis.

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Purpose: Aortopathy, characterized by aortic dilatation caused by cystic medial necrosis, typically develops in adulthood but has been observed at a young age in patients with tetralogy of Fallot. We hypothesized that some patients with tetralogy of Fallot or double-outlet right ventricle experience early-onset aortic disturbed flow. This study aimed to identify and analyze the causes of disturbed flow using 4D flow MRI.

Methods: This study included 24 patients who underwent 4D flow MRI at our institution between January 2022 and September 2024. MRI and cardiac catheterization were performed during follow-up. 4D flow MRI was used to detect disturbed flow and investigate its underlying causes.

Results: The mean age of patients with tetralogy of Fallot or double-outlet right ventricle was 12 years (range, 1 to 37 years). Of the 24 participants, 11 (46%) exhibited disturbed flow. Patients with disturbed flow had significantly higher Valsalva Z-scores (4.7 ± 3.1 vs. 2.4 ± 1.4, P = 0.013) and a significantly narrower left ventricular outflow tract-ascending aorta angle (113.5 ± 11.6 vs. 127.1 ±  6.7°, P = 0.002). Wall shear stress and energy loss were not significantly different between the 2 groups.

Conclusion: Aortic disturbed flow may occur in patients with tetralogy of Fallot or double-outlet right ventricle, regardless of age, suggesting an association with the left ventricular outflow tract-ascending aorta angle. The occurrence of disturbed flow at a young age should be noted as it may contribute to the future progression of aortopathy.

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Purpose: To assess the effects of industry-developed deep learning reconstruction with super resolution (DLR-SR) on single-shot turbo spin-echo (SshTSE) images with thickness of 2 mm with DLR (SshTSE^2mm) relative to those of images with a thickness of 5 mm with DLR (SSshTSE^5mm) in the patients with pancreatic cystic lesions.

Methods: Thirty consecutive patients who underwent abdominal MRI examinations because of pancreatic cystic lesions under observation between June 2024 and July 2024 were enrolled. We qualitatively and quantitatively evaluated the image qualities of SshTSE^2mm and SshTSE^5mm with and without DLR-SR.

Results: The SNRs of the pancreas, spleen, paraspinal muscle, peripancreatic fat, and pancreatic cystic lesions of SshTSE^2mm with and without DLR-SR did not decrease in compared to that of SshTSE^5mm with and without DLR-SR. There were no significant differences in contrast-to-noise ratios (CNRs) of the pancreas-to-cystic lesions and fat between 4 types of images. SshTSE^2mm with DLR-SR had the highest image quality related to pancreas edge sharpness, perceived coarseness pancreatic duct clarity, noise, artifacts, overall image quality, and diagnostic confidence of cystic lesions, followed by SshTSE^2mm without DLR-SR and SshTSE^5mm with and without DLR-SR (P  <  0.0001).

Conclusions: SshTSE^2mm with DLR-SR images had better quality than the other images and did not have decreased SNRs and CNRs. The thin-slice SshTSE with DLR-SR may be feasible and clinically useful for the evaluation of patients with pancreatic cystic lesions.

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A novel imaging technique, CT-like MRI, specifically Fast Field Echo Resembling a CT Using Restricted Echo-spacing (FRACTURE), has been developed to depict bones. The purpose of this study is to evaluate the feasibility of FRACTURE MRI in cranial and facial bone lesions. Our results suggest that FRACTURE MRI can be used in addition to conventional MRI to evaluate a variety of pathologies of the cranial and facial bones.

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Purpose: To evaluate the effect of model-based deep-learning reconstruction (DLR) compared with that of compressed sensing–sensitivity encoding (CS) on cine cardiac magnetic resonance (CMR).

Methods: Cine CMR images of 10 healthy volunteers were obtained with reduction factors of 2, 4, 6, and 8 and reconstructed using CS and DLR. The visual image quality scores assessed sharpness, image noise, and artifacts. Left-ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were manually measured. LV global circumferential strain (GCS) was automatically measured using the software. The precision of EDV, ESV, SV, EF, and GCS measurements was compared between CS and DLR using Bland–Altman analysis with full-sampling data as the gold standard.

Results: Compared with CS, DLR significantly improved image quality with reduction factors of 6 and 8. The precision of EDV and ESV with a reduction factor of 8, and GCS with reduction factors of 6 and 8 measurements improved with DLR compared with CS, whereas those of SV and EF measurements were not different between DLR and CS.

Conclusion: The effect of DLR on cine CMR’s image quality and precision in evaluating quantitative volume and strain was equal or superior to that of CS. DLR may replace CS for cine CMR.

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We have proposed a T2-based free water suppression diffusion MRI (T2wsup-dMRI) technique to address parameter quantification issues due to cerebrospinal fluid (CSF) partial volume effects (PVEs), using a closed form (CF) algorithm. This study optimizes data patterns in (TE, b-value) space and analyzes algorithms for enhanced accuracy and precision. We simulated noise-added numerical, phantom, and brain MRI data to evaluate relative error and coefficient of variation in quantitative parameters using various data patterns and analysis algorithms (CF and least squares [LSQ] fitting). With 4 minimum data points applied to healthy brain tissue with T2 < 100 ms, the CF algorithm with water volume separation was optimal. For more than 4 points, a smaller b-value with shorter TE combined with 2d single- and bi-exponential LSQ fitting provided the best results. The T2wsup-dMRI technique reduces CSF-PVE artifacts in tissue-specific parameter quantification, enhancing approaches for patient needs, data acquisition, and computing costs.

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Purpose: Diffusion models (DMs) excel in pixel-level and spatial tasks and are proven feature extractors for 2D image discriminative tasks when pretrained. However, their capabilities in 3D MRI discriminative tasks remain largely untapped. This study seeks to assess the effectiveness of DMs in this underexplored area.

Methods: We use 59830 T1-weighted MR images (T1WIs) from the extensive, yet unlabeled, UK Biobank dataset. Additionally, we apply 369 T1WIs from the BraTS2020 dataset specifically for brain tumor classification, and 421 T1WIs from the ADNI1 dataset for the diagnosis of Alzheimer’s disease. Firstly, a high-performing denoising diffusion probabilistic model (DDPM) with a U-Net backbone is pretrained on the UK Biobank, then fine-tuned on the BraTS2020 and ADNI1 datasets. Afterward, we assess its feature representation capabilities for discriminative tasks using linear probes. Finally, we accordingly introduce a novel fusion module, named CATS, that enhances the U-Net representations, thereby improving performance on discriminative tasks.

Results: Our DDPM produces synthetic images of high quality that match the distribution of the raw datasets. Subsequent analysis reveals that DDPM features extracted from middle blocks and smaller timesteps are of high quality. Leveraging these features, the CATS module, with just 1.7M additional parameters, achieved average classification scores of 0.7704 and 0.9217 on the BraTS2020 and ADNI1 datasets, demonstrating competitive performance with that of the representations extracted from the transferred DDPM model, as well as the 33.23M parameters ResNet18 trained from scratch.

Conclusion: We have found that pretraining a DM on a large-scale dataset and then fine-tuning it on limited data from discriminative datasets is a viable approach for MRI data. With these well-performing DMs, we show that they excel not just in generation tasks but also as feature extractors when combined with our proposed CATS module.

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Purpose: Glymphatic system impairment has been suggested in previous animal and human studies regarding traumatic brain injury (TBI). Diffuse axonal injury (DAI) is an important pathological feature of TBI and is frequently diagnosed in patients with moderate to severe TBI. This study evaluated the glymphatic system function in patients with DAI using diffusion tensor imaging analysis along the perivascular space (DTI-ALPS), a non-invasive technique.

Methods: A total of 162 patients with TBI, including 84 with DAI and 78 without DAI, underwent MRI with DTI within 6 months of the date of injury. The ALPS index was calculated to assess the glymphatic system activity and compared between patients with and without DAI. Analysis of covariance (ANCOVA) was used to compare the ALPS index between patients with DAI grades 1, 2, and 3. Correlation analysis was performed between the ALPS index, DAI grade, and Glasgow Coma Scale (GCS) score.

Results: Patients with DAI (1.29 ± 0.17) had a significantly lower ALPS index than those without DAI (1.42 ± 0.19, P < 0.001). The ALPS index differed significantly between patients with different DAI grades (ANCOVA, P < 0.001). The ALPS index and DAI grades were negatively correlated (r =−0.47, P < 0.001). The ALPS index and GCS scores showed a weak positive correlation (r = 0.174, P = 0.027).

Conclusions: Patients with DAI have a lower ALPS index, indicating impaired glymphatic system activity, which is more severe in patients with a higher DAI grade. These findings broaden the understanding of the pathophysiology of DAI and help predict patients’ prognoses and recovery trends.

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Multiparametric quantitative MRI (MP-qMRI) methods, which measure multiple relaxation times simultaneously, are becoming into practical tools, but the relationship between different MP-qMRI methods has not been clarified. In particular, since 2D multidynamic multiple-echo (2D-MDME) was provided by multiple major MRI vendors, many patient studies have been reported, but its relationship with 3D-QALAS (3D-QuAntification using an interleaved Look-Locker Acquisition Sequence with T₂ preparation pulse), which is expected to be its 3D version successor, is unknown. In this study, we implemented 2D-MDME and 3D-QALAS on an originally designed 1.5T and a clinical 3T MRI systems, and measured relaxation times of phantoms, focusing on the effect of magnetization transfer (MT) effect on T₁ measurements. As a result, in 2D-MDME, T₁ shortening effects of around 20%–35% was observed due to the MT effect, and in 3D-QALAS, no effect of the MT effect on the T₁ measurements was observed. Therefore, we concluded that the MT effect needs to be considered when comparing MP-qMRI methods in clinical studies.

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Stroke is a major cause of disability and death in adults worldwide. In clinical setting, time efficient MRI protocols including diffusion weighted images, fluid attenuated inversion recovery, fast T2*-weighted images and MR angiography aim to establish ischemic stroke diagnosis, visualize vessel occlusion and determine the extent of ischemia damage distinguishing between the salvageable ischemic penumbra and the infarct core. Thus, MRI plays a pivotal role in diagnosis, treatment decision-making, and prognostic assessment, although prediction based on these elements remains limited and can be improved. We reviewed the added-values of alternative MRI methods such as sodium(²³Na) MRI and ¹H MR spectroscopic imaging that open new temporal and pathophysiological windows on ionic dys-homeostasis and metabolism alteration in the context of ischemic stroke and reperfusion. Insights on the timeline of the cellular events accessible using these alternative methods and perspectives to improve clinical outcome prediction of ischemic stroke patients are discussed.

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Purpose: These guidelines aim to support MRI diagnosis in patients receiving anti-amyloid β (Aβ) antibody treatment without restricting treatment eligibility.

Materials and Methods: These guidelines were collaboratively established by Japan Radiological Society, The Japanese Society of Neuroradiology, and Japanese Society for Magnetic Resonance in Medicine by reviewing existing literature and the results of clinical trials.

Results: Facility standards should comply with the “Optimal Use Promotion Guidelines” of Japan, and physicians should possess comprehensive knowledge of amyloid-related imaging abnormalities (ARIA) and expertise in brain MRI interpretation. The acquisition of knowledge regarding amyloid-related imaging abnormalities, brain MRI, anti-Aβ antibody introduction, and post-treatment diagnosis are also recommended.

Conclusion: These guidelines facilitate the accurate diagnosis and effective management of ARIA; ensure the safe administration of anti-Aβ drugs; and provide a framework for MRI facilities, includes staffing requirements and the use of MRI management systems.

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