Purpose: To investigate relationships among relaxation, susceptibility, and diffusion parameters in healthy white matter (WM) and to characterize WM MRI feature organization using an integrative multimodal quantitative MRI framework.

Methods: Twenty-two healthy volunteers underwent 3T MRI. Quantitative parameter mapping provided R₁, R₂*, R₁·R₂*, and quantitative susceptibility mapping, while diffusion kurtosis imaging provided fractional anisotropy (FA), mean kurtosis, axial kurtosis (AK), and radial kurtosis. All maps were spatially normalized to Montreal Neurological Institute (MNI) space, and mean values were extracted from WM tracts defined by the Johns Hopkins University (JHU) White Matter Atlas. Pearson correlation analysis with false discovery rate correction, principal component analysis (PCA), hierarchical clustering, and bootstrap stability analysis were performed.

Results: The first 2 principal components explained 77.7% of the total variance. The first principal component (PC1) was mainly associated with relaxation-related parameters and diffusion kurtosis metrics, whereas the second principal component (PC2) was characterized by opposing contributions from AK and FA. Quantitative susceptibility mapping showed weak correlations with other parameters (r = −0.37 to −0.08), suggesting relatively independent susceptibility-related information. The PCA structure was preserved after excluding R₁·R₂*, and bootstrap analysis supported loading stability, with mean loading correlations of 0.94 for PC1 and 0.90 for PC2. WM tracts formed 4 major cluster-like groups and showed tract-specific multimodal fingerprints.

Conclusion: Multimodal quantitative MRI provides a concise tract-level MRI feature representation of WM by integrating relaxation, susceptibility, and diffusion information. This exploratory framework may support future studies investigating subtle WM alterations, although validation in pathological cohorts is required.

Purpose: Most existing multi-contrast MRI super-resolution (MCMSR) methods rely on spatial-domain fusion and global attention, overlooking explicit high-frequency (HF) priors while incurring high computational costs. This work addresses these limitations through a general reference-guided MCMSR framework designed for low computational cost, applicable to any contrast pairing rather than a fixed clinical protocol.

Methods: We introduce a wavelet-guided HF prior modeling block for directional-based decomposition and bounded nonlinear enhancement, enabling precise extraction and controlled amplification of anatomical details from both reference and target contrasts. We further introduce a triple cross-contrast fusion module, based on a windowed cross-contrast attention module, to efficiently transfer high-frequency information between contrasts and reduce computational complexity compared to global attention schemes. Additionally, to reduce feature differences across contrasts, a consistent feature fusion module with selective spatial adaptive modulation is incorporated.

Results: Extensive experiments on IXI and M4Raw datasets demonstrate that our proposed windowed cross-contrast attention network (WCCAN) framework consistently outperforms state-of-the-art single and multi-contrast MRI SR methods in terms of quantitative accuracy and visual fidelity. In addition, the WCCAN model achieves lower computational complexity and faster inference time compared to the other MCMSR methods.

Conclusion: The proposed WCCAN framework provides an efficient and accurate solution for MCMSR, demonstrating superior reconstruction quality with reduced computational cost compared to existing methods.

This study aimed to demonstrate the technical feasibility of a dedicated prostate phantom for standardized qualitative evaluation of diffusion-weighted MRI sequences, focusing on signal-to-noise characteristics and image artifacts. A custom-designed phantom simulating prostate tissue, tumor lesions, and rectal gas was used to evaluate 6 diffusion-weighted imaging techniques at 1.5 and 3.0 tesla. Quantitative assessments included signal-to-noise measurements and susceptibility artifacts, while spatial distortion was evaluated by comparison with T2-weighted imaging. Qualitative image quality was assessed using corresponding clinical images as references. Clinical images were evaluated by a radiologist and a urologist, and phantom images were evaluated by 2 radiological technologists. The phantom demonstrated high inter-reader agreement for qualitative image assessment. Clinical image evaluation was performed to confirm whether artifact trends observed in the phantom were similarly observed in clinical images and showed comparable tendencies across sequences. These findings indicate that the proposed prostate phantom provides a practical and reproducible platform for qualitative evaluation.

Whole-body MRI (WB-MRI) has evolved over the past 2 decades as a noninvasive imaging technique for detecting distant metastases in prostate cancer. Since the introduction of diffusion-weighted imaging with background body signal suppression by Takahara et al. in 2004, its clinical use has expanded rapidly, particularly in the detection of bone metastases. WB-MRI offers whole-body coverage without radiation exposure and can be completed within approximately 30 minutes, making it suitable for repeated examinations. Consequently, it is now applied not only for metastasis detection but also for treatment response evaluation. Diffusion-weighted imaging further enables semi-quantitative assessment of tumor burden by measuring total tumor diffusion volume. Nevertheless, manual processing and interinstitutional standardization remain limitations that hinder widespread clinical adoption. Recent advances in deep learning and quantitative imaging are expected to overcome these issues through automated lesion extraction and volumetric analysis. Moreover, comparative studies have shown that WB-MRI and prostate-specific membrane antigen positron emission tomography can serve as complementary modalities. The integration of both techniques will enhance diagnostic accuracy, facilitate individualized treatment strategies, and contribute to establishing WB-MRI as a next-generation imaging standard in prostate cancer management.

Purpose: To establish a new hepatic alveolar echinococcosis (HAE) model, construct an EPC1 antibody–conjugated superparamagnetic iron oxide nanoparticle (SPION) molecular probe and evaluate the probe’s efficacy in the targeted MRI of HAE.

Methods: Thirty C57 female mice (9–10 weeks; 17–22g) were used to establish an HAE model via hepatic portal vein infection. Twenty successfully HAE-modeled mice were randomly divided into a control group, which was given a simple SPION tracer, and an experimental group, which was given a complex SPION–EPC1 tracer. In addition, a blocking group (n = 5), in which mice received an excess dose of free EPC1 antibody prior to injection of the SPION–EPC1 tracer, was included to assess EPC1-dependent targeting, and a gadolinium–diethylene triamine pentaacetic acid (Gd-DTPA) group (n = 5), which received 0.1 mmol/kg of Gd-DTPA, was included to provide a reference clinical contrast agent. MRI was performed using an animal MRI scanner, and T1- and T2-weighted imaging sequences were utilized to assess lesion characteristics before and after tracer injection at 1 and 4h time points. Subsequently, T2 signal intensity, the lesion SNR, and the lesion-to-liver contrast-to-noise ratio were measured by 2 blinded physicians (>5 years experience) using ImageJ software. Comparisons were made between plain and post-injection scans at 1 and 4h. Independent sample t-tests and non-parametric tests were applied to compare signal intensities and SNR values.

Results: The SPION–EPC1 probe significantly decreased T2 signal intensity and lesion SNR in the experimental group at both 1 (T2 intensity: –24.3%; SNR: –35.2%) and 4h (T2 intensity: –23.5%; SNR: –43.1%) compared with plain scans. By contrast, the control group showed only transient decreases, with no significant differences at 4h. In the EPC1-blocking group, the T2-signal decrease at 4h was markedly attenuated compared with that of the SPION–EPC1 group and comparable to that of the SPION group, supporting EPC1-dependent targeting.

Conclusion: The SPION–EPC1 molecular probe demonstrated improved sensitivity and long-lasting effects in the MRI detection of HAE lesions, offering a promising tool for early diagnosis and the potential advancement of clinical practice in HAE imaging.

Purpose: To evaluate the monitoring value of T1 and T2 mapping in assessing kidney injury associated with chronic liver disease and the therapeutic efficacy of bone marrow mesenchymal stem cells (BMSCs) treatment.

Methods: Thirty-six rats were divided into 6 subgroups (n = 6/group) and underwent MRI scanning at 0, 2, 4, 6, 8, and 12 weeks, respectively, followed by biochemical and histological analyses. Seven rats underwent continuous MRI scanning to monitor changes in imaging parameters. Twenty-four rats divided into BMSC and control group. Six rats per group were subjected to serial MRI scans at weeks 13, 14, 15, and 16, another six rats per group were scanned at week 14 and then sacrificed for biochemical and renal histological analysis.

Results: From baseline to 12 weeks, renal hematoxylin and eosin (HE) scores and α-smooth muscle actin (α-SMA) levels increased significantly, and similar trends were found in renal T1 and T2 values. Following BMSCs injection, both BMSC and control groups exhibited reductions in HE scores and α-SMA levels, with BMSC group demonstrating more substantial decreases. Renal T1 and T2 values declined in both groups, with the BMSC group showing significantly lower T2 values than the control group. Strong correlations were found between renal T1/T2 values and HE scores, α-SMA levels (|r|=0.419–0.724). The area under the curve values for T1 and T2 in differentiating renal injury severity across different renal strips were from 0.793 to 0.930.

Conclusion: T1 and T2 mapping can effectively monitor renal injury progression in chronic liver disease, with T2 values demonstrating greater potential for assessing the therapeutic efficacy of BMSCs.

Purpose: The postmortem interval (PMI) alters tissue properties that shape quantitative MRI (qMRI) signals. We systematically investigated the effects of PMI on relaxation times, depending on tissue characteristics, in both unfixed and fixed pig brains.

Methods: Twelve pig brains (n = 12) were scanned in both unfixed and fixed states at 3 PMI windows (≈12, 24, 48h). Quantitative T1, T2, and T2* maps were acquired with identical protocols at controlled room temperature (~24°C). We assessed the PMI effects on relaxation times in the gray matter (GM) and the white matter (WM) at both group and sample levels, while fixation-induced effects and inter-sample variability were evaluated using pairwise rank correlation and coefficient of variation (CV) visualization.

Results: In unfixed tissues, T1 significantly differed among PMI groups in GM (P = 0.0141) and WM (P = 0.0315) in the early window (≤24h). In the same window, PMI–T1 correlations were observed in both GM (r = 0.921, P = 0.007) and WM (r = 0.876, P = 0.013). T2 showed no group differences but exhibited an inverse correlation with PMI in WM (r = −0.849, P = 0.015). No significant PMI–T2* relationships were detected (all P > 0.05). At later PMI (20–50h), PMI–qMRI correlations diminished. Fixation processes altered all qMRI parameters. Notably, the PMI effects on T1 in the unfixed brains were preserved even after fixation at an ordinal level, although fixation introduced substantial inter-sample variability.

Conclusion: PMI exerts the most robust effects on T1. Fixation has a significant impact on qMRI values, mitigating the apparent PMI effect and increasing the inter-sample variability. However, it is still possible to retrieve the PMI effects from fixed brain at the level of rank order, providing practical guidance for further ex vivo qMRI studies on PMI.

Purpose: The present study directly compared the quantitative capabilities of regional perfusion and pulmonary functional change assessments among electrocardiography (ECG)- and photoplethysmography (PPG)-monitored phase-resolved functional lung (PREFUL) MRI and dynamic contrast-enhanced (CE) perfusion MRI in thoracic oncologic patients.

Methods: Seventeen thoracic oncologic patients prospectively underwent ECG- and PPG-monitored PREFUL MRI, dynamic CE-perfusion MRI, and pulmonary function tests. ECG- and PPG-monitored perfusion-weighted PREFUL MRI (PW-MRI) and quantitative perfusion maps from dynamic CE-perfusion MRI were generated. Regional perfusions were determined using ROI measurements. For each patient, the overall perfusion from each method was determined as the average ROI measurement value. To determine the relationship between regional perfusion among all methods, Pearson’s correlations were performed. Tukey’s honest significant difference test was performed to compare regional perfusion among ventral, middle, and dorsal slice positions on ECG- and PPG-monitored PW-MRI and quantitative perfusion maps. To assess the pulmonary functional loss evaluation capability of each MRI method, each overall perfusion was correlated with %VC and %FEV₁ using Pearson’s correlation.

Results: The correlation of regional perfusion between ECG- and PPG-monitored PW-MRI was significant and good (r = 0.79, P < 0.0001). However, the correlations between ECG- or PPG-monitored PW-MRI and quantitative perfusion maps were assessed as significant and fair (ECG: r = 0.4, P < 0.0001; PPG: r = 0.36, P < 0.0001). ECG- and PPG-monitored PW-MRI demonstrated significantly higher perfusion than the quantitative perfusion map (P < 0.0001). Furthermore, ECG-and PPG-monitored PW-MRI and quantitative perfusion maps had significant and moderate correlations (%VC: 0.60 ≤ r ≤ 0.63, P < 0.05; %FEV₁: 0.52 ≤ r ≤ 0.69, P < 0.05).

Conclusion: ECG- and PPG-monitored PREFUL MRI had similar potential to dynamic CE-perfusion MRI for quantitatively assessing regional perfusion and pulmonary functional changes in thoracic oncologic patients. Furthermore, PPG-monitored PREFUL MRI showed little difference in regional perfusion evaluation compared with ECG-monitored PREFUL MRI and the potential to play a complementary role in this setting.

Purpose: The primary objective of this study was to determine the relationship between Wingate test, athletic performance, and MRI parameters in athletes. Additionally, we examined whether there were significant differences in these parameters between athletes and non-athletes during dorsiflexion exercises.

Methods: Twenty-two male athletes and 9 non-athletes performed dorsiflexion exercises with a 4-kg load. MRI scans, including T2* mapping and diffusion tensor imaging, were conducted pre-exercise, immediately after exercise, and 30 minutes post-exercise. Quantitative parameters, including T2* values, fractional anisotropy, mean diffusivity, and eigenvalues (λ2, λ3), were analyzed. Wingate test results and athletics scoring based on the 2022 World Athletics Scoring Tables were used to evaluate anaerobic power and sprint performance.

Results: MRI parameters, particularly T2* changes and λ3, showed significant correlations with Wingate test results and athletic performance. Pre-exercise λ3, reflecting muscle fiber orientation and thickness, emerged as a key predictor of athletic performance alongside T2* changes and Wingate power. The integration of MRI-derived metrics with Wingate test results improved the prediction of athletic scores compared to Wingate power alone. Although differences between athletes and non-athletes in T2* and λ2 were observed, these findings serve as supplementary evidence supporting the role of MRI in identifying muscle characteristics critical for athletic performance.

Conclusion: MRI-derived parameters combined with performance tests can provide valuable insights into muscle recovery, structure, and athletic performance, with potential for predicting athlete scores and optimizing training strategies.

This study aimed to clarify the accuracy and variability of heart rate variability effects on T1 relaxation time values acquired using different sampling schemes of the modified Look–Locker inversion recovery (MOLLI) method. Five MOLLI sampling schemes—5(3)3, 5s(3s)3s, 4(1)3(1)2, 4s(1s)3s(1s)2s, and 3(3)3(3)5—were compared using a simulated electrocardiogram signal in a phantom experiment. The 5(3)3 and 5s(3s)3s schemes demonstrated high accuracy across the range of native and contrast-enhanced T1 values, with correlation coefficients exceeding 0.95 compared with the reference T1. Regarding heart rate variability, the 5(3)3 scheme showed minimal variation in the measured value across different heart rates, regardless of the T1 value, with an error rate below 6% relative to the reference T1. Therefore, the 5(3)3 scheme can achieve highly accurate measurements over a wide T1 range and is robust against heart rate variability.

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.

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.

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.

Purpose: This study aimed to compare MRI findings among benign, borderline, and malignant ovarian seromucinous neoplasms.

Methods: We retrospectively analyzed MRI data from 24 patients with ovarian seromucinous neoplasms—seven benign, thirteen borderline, and six malignant. The parameters evaluated included age, tumour size, morphology, number, height, apparent diffusion coefficient (ADC) values, T2 ratios, time-intensity curve (TIC) descriptors, and TIC patterns of the mural nodules. Additionally, we examined the T2 and T1 ratios of the cyst contents, tumour markers, and the presence of endometriosis. We used statistical tests, including the Kruskal–Wallis and Fisher–Freeman–Halton exact tests, to compare these parameters among the three aforementioned groups.

Results: The cases showed papillary architecture with internal branching in 57% of benign, 92% of borderline, and 17% of malignant cases. Three or fewer mural nodules were seen in 57% of benign, 8% of borderline, and 17% of malignant cases. Compared to benign and borderline tumours, mural nodules of malignant neoplasms had significantly increased height (P = 0.015 and 0.011, respectively), lower means ADC values (P = 0.003 and 0.035, respectively). The mural nodules in malignant cases also demonstrated significantly lower T2 ratios than those in the benign cases (P = 0.045). Most neoplasms displayed an intermediate-risk TIC pattern, including 80% benign, 83% borderline, and 60% malignant neoplasms, and no significant differences were observed.

Conclusion: Most benign and borderline tumours exhibited a papillary architecture with an internal branching pattern, whereas this feature was less common in malignant neoplasms. Additionally, benign tumours had fewer mural nodules compared to borderline tumours. Malignant neoplasms were characterized by mural nodules with increased height and lower ADC values than those in benign and borderline tumours. Interestingly, all three groups predominantly exhibited an intermediate-risk TIC pattern, emphasizing the complexity of diagnosing seromucinous neoplasms using MRI.

Purpose: The aim of our study was to investigate the technical accuracy of susceptibility-weighted imaging (SWI) and quantitative susceptibility mapping (QSM) created to detect intramammary-like calcifications depending on different TEs, volume, and type of calcification samples at 1.5T.

Methods: Jello-embedded particles of blackboard chalk and ostrich eggshell ranging in size from 4 to 25 mm² were used to simulate intramammary calcifications after testing different base substances and calcifications for their suitability to be used in breast phantoms. Breast phantoms were systematically examined using CT and an optimized 3D multi-echo gradient echo pulse sequence with following parameters: TR/TE, 22/1.88–15.52 ms in 1.24 ms increments; reconstructed voxel, 0.5 × 0.5 × 1.1 mm³; receiver bandwidth, 1120 Hz/Px; flip angle, 15°; integrated parallel imaging technique with a GeneRalized Autocalibrating Partial Parallel Acquisition (GRAPPA) factor of 2/24; and a total acquisition time of 3:00 min. A qualitative evaluation of the dependence of the visualization of calcification samples on volume and TE value was followed by a calculation of the SNR, the contrast-to-noise ratio (CNR) and the creation of SWI and QSM in the sense of a (semi)-quantitative analysis of the images.

Results: Jello proved to be a suitable base substance for preparing breast phantoms for SW MRI. Blackboard chalk and ostrich eggshell proved to be suitable for mimicking intramammary-like calcifications. The decrease in the median SNR of the blackboard chalk samples was significantly higher than the corresponding value of the ostrich eggshell samples over the entire TE range (47.5 to 17.0 vs. 16.0 to 6.56, P < 0.0001). The increase in the median CNR of the blackboard chalk samples was significantly higher than the corresponding value of the ostrich eggshell samples over the entire TE range (2.46 to 35.0 vs. 20.2 to 36.8, P = 0.007). With increasing TE value, the signal void volume of the calcification particle increases in the magnitude images as well as in SWI and QSM. Due to the blooming effect, the median gradients of the TE-based changes in signal void volumes were higher in SWI than in magnitude images and in QSM, regardless of the type of calcification particle examined. The maximum magnetic susceptibility of ostrich eggshell samples varied in a TE range of 1.88 to 15.52 ms from −7.2 to −2.51 ppm and that of blackboard chalk from −2.0 to −1.7 ppm. Compared to the manually measured volumes of the calcification particles, both MR-based measurements and CT examinations overestimated the actual sample size. The (non)-significant overestimation in the MRI-data is dependent on the set TE. The CT-based hyperdense volumes were overestimated compared to the corresponding manually measured sample volumes in a range of 109.8%–315.2% for ostrich eggshell samples (P = 0.016) and in a range of 39.9%–156.4% for blackboard chalk samples (P = 0.69).

Conclusion: Our systematic in-vitro investigation of magnitude images, SWI, and QSM revealed that various set TE values, different volumes, and compositions of calcifications have a significant impact on visualizing intramammary(-like) calcifications.

The quantitative analysis of pulsed-chemical exchange saturation transfer (CEST) using a full model-based method is computationally challenging, as it involves dealing with varying RF values in pulsed saturation. A power equivalent continuous approximation of B₁ power was usually applied to accelerate the analysis. In line with recent consensus recommendations from the CEST community for pulsed-CEST at 3T, particularly recommending a high RF saturation power (B₁ = 2.0 µT) for the clinical application in brain tumors, this technical note investigated the feasibility of using average power (AP) as the continuous approximation. The simulated results revealed excellent performance of the AP continuous approximation in low saturation power scenarios, but discrepancies were observed in the z-spectra for the high saturation power cases. Cautions should be taken, or it may lead to inaccurate fitted parameters, and the difference can be more than 10% in the high saturation power cases.

A chemically fixed Carnegie stage 23 (approximately 56 days of gestation) human embryo specimen was imaged using 3D spin-echo and gradient-echo sequences in a static magnetic field strength of 4.74T, and a quantitative susceptibility map was calculated using the 3D gradient-echo image. The acquired 3D microscopic images (90 μm cube voxel size) clarified the relationship between R₂ (transverse relaxation rate), R₂* (apparent transverse relaxation rate), and magnetic susceptibility in the heart, liver, kidney, and spinal cord. The results suggested that the R₂* and magnetic susceptibility in each tissue were probably due to paramagnetic iron ions originating from erythrocytes. The large R₂* (~130 s^-1) and magnetic susceptibility (~0.122 ppm) in the liver were attributed to its hemopoietic function. A large magnetic susceptibility (~0.116 ppm) was also observed in the spinal cord, but we conclude that more detailed future studies are needed.

¹⁷O-labeled water is a T2-shortening contrast agent used in proton MRI and is a promising method for visualizing cerebrospinal fluid (CSF) dynamics because it provides long-term tracking of water molecules. However, various external factors reduce the accuracy of ¹⁷O-concentration measurements using conventional signal-intensity-based methods. In addition, T2 mapping, which is expected to provide a stable assessment, is generally limited to temporal–spatial resolution. We developed the T2-prepared based on T2 mapping used in cardiac imaging to adapt to long T2 values and tested whether it could accurately measure ¹⁷O-concentration in the CSF using a phantom. The results showed that ¹⁷O-concentration in a fluid mimicking CSF could be evaluated with an accuracy comparable to conventional T2-mapping (Carr–Purcell–Meiboom–Gill multi-echo spin-echo method). This method allows ¹⁷O-imaging with a high temporal resolution and stability in proton MRI. This imaging technique may be promising for visualizing CSF dynamics using ¹⁷O-labeled water.

Purpose: Here, we aimed to characterize the cortical and subcortical microstructural alterations in the brains of patients with amyotrophic lateral sclerosis (ALS). In particular, we compared these features between bulbar-onset ALS (b-ALS) and limb-onset ALS (l-ALS).

Methods: Diffusion MRI data (b = 0, 700, 2000 ms/mm², 1.7-mm isotropic voxel) from 28 patients with ALS (9 b-ALS and 19 l-ALS) and 17 healthy control subjects (HCs) were analyzed. Diffusional kurtosis imaging (DKI) metrics were sampled at the mid-cortical and subcortical surfaces. We used permutation testing with a nonparametric combination of mean diffusivity (MD), fractional anisotropy (FA), and mean kurtosis (MK) to assess intergroup differences over the cerebrum. We also carried out an atlas-based analysis focusing on Brodmann Area 4 and 6 (primary motor and premotor areas) and investigated the correlation between MRI metrics and clinical parameters.

Results: At both the mid-cortical and subcortical surfaces, b-ALS was associated with significantly greater MD, smaller FA, and smaller MK in the motor and premotor areas than HC. In contrast, the patients with l-ALS showed relatively moderate differences relative to HCs. The ALS Functional Rating Scale-Revised bulbar subscore was significantly correlated with the diffusion metrics in Brodmann Area 4.

Conclusion: The distribution of abnormalities over the cerebral hemispheres and the more severe microstructural alteration in b-ALS compared to l-ALS were in good agreement with findings from postmortem histology. Our results suggest the feasibility of surface-based DKI analyses for exploring brain microstructural pathologies in ALS. The observed differences between b-ALS and l-ALS and their correlations with functional bulbar impairment support the clinical relevance of DKI measurement in the cortical and juxtacortical regions of patients with ALS.

Synthetic MRI is being increasingly used for the quantification of brain longitudinal relaxation time (T1), transverse relaxation time (T2), and proton density (PD) values. However, the effect of fast imaging protocols on these quantitative values has not been fully estimated. The purpose of this study was to investigate the effect of fast scan parameters on T1, T2, and PD measured with a multi-dynamic multi-echo (MDME) sequence of normal brain at 3.0T. Thirty-four volunteers were scanned using 3 MDME sequences with different scan times (named Fast, 2 min, 29 sec; Routine, 4 min, 07 sec; and Research, 7 min, 46 sec, respectively). The measured T1, T2, and PD in 18 volumes of interest (VOI) of brain were compared between the 3 sequences using rank sum test, t test, coefficients of variation (CVs) analysis, correlation analysis, and Bland-Altman analysis. We found that even though T1, T2, and PD were significantly different between the 3 sequences in most of the brain regions, the intersequence CVs were relatively low and linear correlation were high. Bland-Altman plots showed that most of the values fall within the 95% prediction limits. We concluded that fast imaging protocols of MDME sequence used in our study can potentially be used for quantitative evaluation of brain tissues. Since changing scan parameters can affect the measured T1, T2, and PD values, it is necessary to use consistent scan parameter for comparing or following up cases quantitatively.