Conventional Magnetic Resonance Research Articles

NOE analysis using dual injection DNP‐NMR for studies of solvent–solute interactions at low concentrations

AbstractDynamic nuclear polarization (DNP) offers significant signal enhancement compared to conventional nuclear magnetic resonance (NMR) in measuring the nuclear Overhauser effect. Owing to this enhancement, DNP enables the quantitative analysis of solvent–solute interactions, which are typically challenging to assess using standard NMR techniques. However, current experimental setups generally require the use of samples with relatively high solute concentrations because of large dilution factors. This limits the studies on solvent–solute interactions for bio‐related molecules, particularly those with low solubility. In such cases, the concentration of solute post‐dilution often falls below the detection limits. Herein, we introduce a novel dual injection system designed to considerably increase the dilution factor, thereby enabling the use of samples with lower solute concentrations while maintaining detectable signal levels. The effectiveness of this system was demonstrated in experiments using trifluoroacetic acid at concentrations 50 times lower than those used in the conventional method.

Image Quality Assessment Tool for Conventional and Dynamic Magnetic Resonance Imaging Acquisitions

Image quality assessment of magnetic resonance imaging (MRI) data is an important factor not only for conventional diagnosis and protocol optimization but also for fairness, trustworthiness, and robustness of artificial intelligence (AI) applications, especially on large heterogeneous datasets. Information on image quality in multi-centric studies is important to complement the contribution profile from each data node along with quantity information, especially when large variability is expected, and certain acceptance criteria apply. The main goal of this work was to present a tool enabling users to assess image quality based on both subjective criteria as well as objective image quality metrics used to support the decision on image quality based on evidence. The evaluation can be performed on both conventional and dynamic MRI acquisition protocols, while the latter is also checked longitudinally across dynamic series. The assessment provides an overall image quality score and information on the types of artifacts and degrading factors as well as a number of objective metrics for automated evaluation across series (BRISQUE score, Total Variation, PSNR, SSIM, FSIM, MS-SSIM). Moreover, the user can define specific regions of interest (ROIs) to calculate the regional signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), thus individualizing the quality output to specific use cases, such as tissue-specific contrast or regional noise quantification.

Isolated bilateral fornix anterior columns infarction with acute amnesia and fiber tracts damage, a case report

ABSTRACT Isolated fornix anterior column infarction has rarely been described and is difficult to assess accurately using conventional magnetic resonance imaging (MRI). We report the case of a 75-year-old female who experienced acute anterograde amnesia. MRI performed within 24 h after amnesia onset showed an isolated infarction of the bilateral anterior columns of the fornix on diffusion-weighted imaging (DWI). Her symptoms persisted for up to 50 days, and diffusion tensor imaging (DTI) showed disruption of the fiber tracts of the fornix. when acute amnesia syndrome onset, fornix anterior column infarction should be considered, and optimized DWI and DTI methods are needed to study the fornix in vivo in future research.

Whole-Body Hypothermia vs Targeted Normothermia for Neonates With Mild Encephalopathy

Although whole-body hypothermia is widely used after mild neonatal hypoxic-ischemic encephalopathy (HIE), safety and efficacy have not been evaluated in randomized clinical trials (RCTs), to our knowledge. To examine the effect of 48 and 72 hours of whole-body hypothermia after mild HIE on cerebral magnetic resonance (MR) biomarkers. This open-label, 3-arm RCT was conducted between October 31, 2019, and April 28, 2023, with masked outcome analysis. Participants were neonates at 6 tertiary neonatal intensive care units in the UK and Italy born at or after 36 weeks' gestation with severe birth acidosis, requiring continued resuscitation, or with an Apgar score less than 6 at 10 minutes after birth and with evidence of mild HIE on modified Sarnat staging. Statistical analysis was per intention to treat. Random allocation to 1 of 3 groups (1:1:1) based on age: neonates younger than 6 hours were randomized to normothermia or 72-hour hypothermia (33.5 °C), and those 6 hours or older and already receiving whole-body hypothermia were randomized to rewarming after 48 or 72 hours of hypothermia. Thalamic N-acetyl aspartate (NAA) concentration (mmol/kg wet weight), assessed by cerebral MR imaging and thalamic spectroscopy between 4 and 7 days after birth using harmonized sequences. Of 225 eligible neonates, 101 were recruited (54 males [53.5%]); 48 (47.5%) were younger than 6 hours and 53 (52.5%) were 6 hours or older at randomization. Mean (SD) gestational age and birth weight were 39.5 (1.1) weeks and 3378 (380) grams in the normothermia group (n = 34), 38.7 (0.5) weeks and 3017 (338) grams in the 48-hour hypothermia group (n = 31), and 39.0 (1.1) weeks and 3293 (252) grams in the 72-hour hypothermia group (n = 36). More neonates in the 48-hour (14 of 31 [45.2%]) and 72-hour (13 of 36 [36.1%]) groups required intubation at birth than in the normothermic group (3 of 34 [8.8%]). Ninety-nine neonates (98.0%) had MR imaging data and 87 (86.1%), NAA data. Injury scores on conventional MR biomarkers were similar across groups. The mean (SD) NAA level in the normothermia group was 10.98 (0.92) mmol/kg wet weight vs 8.36 (1.23) mmol/kg wet weight (mean difference [MD], -2.62 [95% CI, -3.34 to -1.89] mmol/kg wet weight) in the 48-hour and 9.02 (1.79) mmol/kg wet weight (MD, -1.96 [95% CI, -2.66 to -1.26] mmol/kg wet weight) in the 72-hour hypothermia group. Seizures occurred beyond 6 hours after birth in 4 neonates: 1 (2.9%) in the normothermia group, 1 (3.2%) in the 48-hour hypothermia group, and 2 (5.6%) in the 72-hour hypothermia group. In this pilot RCT, whole-body hypothermia did not improve cerebral MR biomarkers after mild HIE, although neonates in the hypothermia groups were sicker at baseline. Safety and efficacy of whole-body hypothermia should be evaluated in RCTs. ClinicalTrials.gov Identifier: NCT03409770.

Diagnostic performance of computed tomography-digital subtraction angiography and conventional magnetic resonance imaging for evaluating the vascularity of osseous spinal tumors

Background and purposePatients with hypervascular spinal tumors may have severe blood loss during tumor resection, which increases the risks of perioperative morbidity and mortality. However, the preoperative evaluation of tumor vascularity may be challenging; moreover, the reliability of the data obtained in conventional preoperative noninvasive imaging is debatable. In this study, we compared conventional magnetic resonance imaging (MRI) and subtraction computed tomography angiography (CTA) in terms of their performance in vascularity evaluation. The catheter digital subtraction angiography (DSA) technique was used as a reference standard. MethodsThis study included 123 consecutive patients with spinal tumor who underwent subtraction CTA, catheter DSA, and subsequent surgery between October 2015 and October 2021. Data regarding qualitative and semiquantitative subtraction CTA parameters and conventional MRI signs were collected for comparison with tumor vascularity graded through catheter DSA. The diagnostic performance of qualitative CTA, quantitative CTA, and conventional MRI in assessing spinal tumor vascularity was analyzed. ResultsQualitative subtraction CTA was the best noninvasive imaging modality in terms of diagnostic performance (area under the receiver operating characteristic curve [AUROC], 0.95). Quantitative CTA was relatively inferior (AUROC, 0.87). MRI results had low reliability (AUROC, 0.51 to 0.59). Intratumoral hemorrhage and prominent foraminal venous plexus were found to be the specific signs for hypervascularity (specificity 93.2%). ConclusionsQualitative subtraction CTA offers the highest diagnostic value in evaluating spinal tumor vascularity, compared to quantitative CTA and MRI. Although conventional MRI may not be a reliable approach, certain MRI signs may have high specificity, which may be crucial for assessing spinal tumor vascularity.

Assessing brain microstructural changes in chronic kidney disease: a diffusion imaging study using multiple models

ObjectivesTo explore the effectiveness of diffusion quantitative parameters derived from advanced diffusion models in detecting brain microstructural changes in patients with chronic kidney disease (CKD).MethodsThe study comprised 44 CKD patients (eGFR<59 mL/min/1.73 m2) and 35 age-and sex-matched healthy controls. All patients underwent diffusion spectrum imaging (DSI) and conventional magnetic resonance imaging. Reconstructed to obtain diffusion MRI models, including diffusion tensor imaging (DTI), neurite orientation dispersion and density imaging (NODDI) and Mean Apparent Propagator (MAP)-MRI, were processed to obtain multi-parameter maps. The Tract-Based Spatial Statistics (TBSS) analysis was utilized for detecting microstructural differences and Pearson correlation analysis assessed the relationship between renal metabolism markers and diffusion parameters in the brain regions of CKD patients. Receiver operating characteristic (ROC) curve analysis assessed the diagnostic performance of diffusion models, with AUC comparisons made using DeLong’s method.ResultsSignificant differences were noted in DTI, NODDI, and MAP-MRI parameters between CKD patients and controls (p < 0.05). DTI indicated a decrease in Fractional Anisotropy(FA) and an increase in Mean and Radial Diffusivity (MD and RD) in CKD patients. NODDI indicated decreased Intracellular and increased Extracellular Volume Fractions (ICVF and ECVF). MAP-MRI identified extensive microstructural changes, with elevated Mean Squared Displacement (MSD) and Q-space Inverse Variance (QIV) values, and reduced Non-Gaussianity (NG), Axial Non-Gaussianity (NGAx), Radial Non-Gaussianity (NGRad), Return-to-Origin Probability (RTOP), Return-to-Axis Probability (RTAP), and Return-to-Plane Probability (RTPP). There was a moderate correlation between serum uric acid (SUA) and diffusion parameters in six brain regions (p < 0.05). ROC analysis showed the AUC values of DTI_FA ranged from 0.70 to 0.793. MAP_NGAx in the Retrolenticular part of the internal capsule R reported a high AUC value of 0.843 (p < 0.05), which was not significantly different from other diffusion parameters (p > 0.05).ConclusionThe advanced diffusion models (DTI, NODDI, and MAP-MRI) are promising for detecting brain microstructural changes in CKD patients, offering significant insights into CKD-affected brain areas.

Multiparametric Mapping via Cardiovascular Magnetic Resonance in the Risk Stratification of Ventricular Arrhythmias and Sudden Cardiac Death

Risk stratification for malignant ventricular arrhythmias and sudden cardiac death is a daunting task for physicians in daily practice. Multiparametric mapping sequences obtained via cardiovascular magnetic resonance imaging can improve the risk stratification for malignant ventricular arrhythmias by unveiling the presence of pathophysiological pro-arrhythmogenic processes. However, their employment in clinical practice is still restricted. The present review explores the current evidence supporting the association between mapping abnormalities and the risk of ventricular arrhythmias in several cardiovascular diseases. The key message is that further clinical studies are needed to test the additional value of mapping techniques beyond conventional cardiovascular magnetic resonance imaging for selecting patients eligible for an implantable cardioverter defibrillator.

Diabetic ketoacidosis with central nervous system involvement: Conventional and advanced magnetic resonance neuroimaging findings.

Diabetic ketoacidosis (DKA) is a serious complication in children with diabetes mellitus type 1 (DM1). In rare and severe cases DKA may be complicated by cerebral edema, central brain herniation and cerebral infarctions. We present the magnetic resonance imaging findings in a child with DKA and central nervous system involvement; diffusion tensor imaging (DTI) and functional MRI (fMRI) were performed to assess the white matter integrity of sensory pathways and cortical sensory processing. Conventional imaging showed bilateral uncal herniation, effacement of the perimesencephalic cisterns, wide ischemic lesions in the posterior cerebral artery (PCA) territories, sagging brainstem and Duret's hemorrhage consistent with signs of central brain herniation and intracranial hypertension. Advanced MRI showed a possible left-sided cortical reorganization for sensory function, with underlying left cortico-talamic and cortico-spinal pathways less severely impaired. Knowledge of the full framework in these conditions is of vital importance for timely patient management; advanced neuroimaging techniques may be considered as prognostic indicators in those cases with extensive involvement of eloquent brain areas.

The role of apparent diffusion coefficient in the grading of adult isocitrate dehydrogenase-mutant astrocytomas: relationship with the Ki-67 proliferation index.

The grading of adult isocitrate dehydrogenase (IDH)-mutant astrocytomas is a crucial prognostic factor. To investigate the value of conventional magnetic resonance imaging (MRI) features and apparent diffusion coefficient (ADC) in the grading of adult IDH-mutant astrocytomas, and to analyze the correlation between ADC and the Ki-67 proliferation index. The clinical and MRI data of 82 patients with adult IDH-mutant astrocytoma who underwent surgical resection and molecular genetic testing with IDH and 1p/19q were retrospectively analyzed. The conventional MRI features, ADCmin, ADCmean, and nADC of the tumors were compared using the Kruskal-Wallis single factor ANOVA and chi-square tests. Receiver operating characteristic (ROC) curves were drawn to evaluate conventional MRI and ADC accuracy in differentiating tumor grades. Pearson correlation analysis was performed to determine the correlation between ADC and the Ki-67 proliferation index. The difference in enhancement, ADCmin, ADCmean, and nADC among WHO grade 2, 3, and 4 tumors was statistically significant (all P <0.05). ADCmin showed the preferable diagnostic accuracy for grading WHO grade 2 and 3 tumors (AUC=0.724, sensitivity=63.4%, specificity=80%, positive predictive value (PPV)=62.0%; negative predictive value (NPV)=82.5%), and distinguishing grade 3 from grade 4 tumors (AUC=0.764, sensitivity=70%, specificity=76.2%, PPV=75.0%, NPV=71.4%). Enhancement + ADC model showed an optimal predictive accuracy (grade 2 vs. 3: AUC = 0.759; grade 3 vs. 4: AUC = 0.799). The Ki-67 proliferation index was negatively correlated with ADCmin, ADCmean, and nADC (all P <0.05), and positively correlated with tumor grade. Conventional MRI features and ADC are valuable to predict pathological grading of adult IDH-mutant astrocytomas.

Application of 3D-PCASL combined with t-ASL and MRA in the diagnosis of patients with isolated vertigo induced by posterior circulation ischemia

ObjectivesIsolated vertigo induced by posterior circulation ischemia (PCIV) can further progress into posterior circulation infarction. This study aimed to explore the diagnostic values of three-dimensional pseudo-continuous arterial spin labeling (3D-PCASL) combined with territorial arterial spin labeling (t-ASL) and magnetic resonance angiography (MRA) in visualizing and evaluating PCIV, seeking improved diagnostic tools for clinical guidance. Methods28 PCIVs (11 males, 17 females, aged from 55 to 83 years, mean age: 69.68 ± 9.01 years) and 28 healthy controls (HCs, 12 male, 16 female, aged from 56 to 87 years, mean age: 66.75 ± 9.86 years) underwent conventional magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), MRA, 3D-PCASL, and t-ASL. We compared the incidence of anatomic variants of the posterior circle of Willis in MRA, cerebral blood flow (CBF) and anterior collateral blood flow on postprocessing maps obtained from 3D-PCASL and t-ASL sequence between PCIVs and HCs. Chi-square test and paired t-test were analyzed statistically with SPSS 24.0 software. Results7 PCIVs (7/28, 25%) and 6 HCs (6/28, 21%) showed fetal posterior cerebral artery (FPCA) on MRA, including 1 HC, and 6 PCIVs with FPCA appeared hypoperfusion. 18 PCIVs (64%) and 2 HCs (7%) showed hypoperfusion in the posterior circulation (PC), including 1 HC and 7 PCIVs displayed anterior circulation collateral flow. Chi-square analyses demonstrated a difference in PC hypoperfusion between PCIVs and HCs, whether in the whole or FPCA-positive group assessment (P < 0.05). Paired t-test showed that the CBF values were significant difference for the bilateral PC asymmetrical perfusion in the PCIVs (P < 0.01). When compared to the bilateral PC symmetrical non-hypoperfusion area in the PCIVs and HCs, the CBF values were not significant (P > 0.05). The CBF values of the PC in PCIVs were lower than in HCs (P < 0.05). The reduction rate in the hypoperfusion side of the bilateral PC asymmetrical perfusion of the PCIVs ranged from 4% to 37%, while the HCs reduction rate was 7.7%. The average PC symmetrical perfusion average reduction rate of the PCIVs was 52.25%, while the HCs reduction rate was 42.75%. Conclusion3D-PCASL is a non-invasive and susceptible method for detecting hypoperfusion in PC, serving as a potential biomarker of PCIV. The suspected hypoperfusion in PC may be attributed to the emergence of FPCA and the manifestation of anterior collateral flow when combining t-ASL and MRA sequences. These findings demonstrated that 3D-PCASL combined with t-ASL and MRA sequences are the potential method to identify PCIV, leading to early diagnosis of PCIV and reducing the risk of progressing into infarction.

Diagnostic accuracy of diffusion-weighted imaging and perfusion-weighted imaging with dynamic susceptibility contrast in differentiating World Health Organization Grade-I meningioma from high-grade meningioma with histopathology as gold standard

Abstract Background: Conventional magnetic resonance imaging may not be able to distinguish between the benign and malignant forms of meningioma. It has some limitations such as differentiating the grades of malignant meningioma. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) techniques can help to overcome these problems. Aims: The aim of this study was to study the diagnostic accuracy of DWI and PWI with dynamic susceptibility contrast in the differentiating World Health Organization Grade-I meningioma from high-grade meningioma with histopathology as the gold standard. Settings and Design: A hospital-based diagnostic evaluation study was carried out at the Department of Radio Diagnosis, Malla Reddy Institute of Medical Sciences, Hyderabad. Materials and Methods: Fifty cases of suspected meningioma were included in the study. The histopathology was the gold standard in this diagnostic evaluation study. DWI and PWI with dynamic susceptibility contrast results were compared against the gold standard. Statistical Analysis: Sensitivity, specificity, positive predictive value, and the negative predictive value were calculated to study the efficacy of DWI compared to histopathology as the gold standard. Results: The males (24%) were lesser than the females (76%). The female-to-male ratio was 3.2:1. The diagnostic accuracy values of apparent diffusion coefficient (ADC) with 0.6 as cutoff were sensitivity = 81.8%, specificity = 97.4%, positive predictive value = 90%, negative predictive value = 95%, and area under curve = 0.98 (95% confidence interval = 0.93–0.99) P = 0.0003. Thus, DWI using ADC with 0.6 as cutoff was found to be a very good diagnostic noninvasive tool. The diagnostic accuracy values of relative cerebral blood volume (rCBV) with 0.6 as cutoff were sensitivity = 90.5%, specificity = 98.7%, positive predictive value = 91.8%, and negative predictive value = 98.5%. Thus, DWI using rCBV with 2.52 as cutoff was found to be a very good diagnostic noninvasive tool. Conclusion: The ADC with cutoff of 0.6 and rCBV with cutoff value of 2.52 yield very good sensitivity, specificity, positive predictive value, and the negative predictive value as compared to histopathology. Hence, they can be used as noninvasive technique in differentiating Grade I meningioma from that of high-grade meningioma.

The predictive value of conventional magnetic resonance imaging combined with intravoxel incoherent motion parameters for evaluating maternal and neonatal clinical outcomes in patients with placenta accreta spectrum disorders

IntroductionWe aimed to identify factors predictive of adverse maternal and neonatal outcomes in patients with placenta accreta spectrum (PAS) disorders using magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) parameters. MethodFifty-six normal singleton pregnancies at 33-39 weeks of gestation underwent MRI examination at 1.5 T. The IVIM parameters were obtained from the placenta. The correlation between the f value and postpartum hemorrhage (PPH) and between the f value and transfused units of red blood cells (RBCs) was estimated by linear regression. The correlation between various influencing factors (clinical risk factors, MRI features, and IVIM parameters) and poor outcomes was investigated using univariate and multivariate analyses. ResultThe interobserver agreement ranged from fair to excellent (k = 0.30–0.88). Multivariate analyses showed that previous cesarean sections, low signal intensity bands on T2WI and the D value were independent risk factors for adverse outcomes. The combination of three risk factors demonstrated the highest AUC of 0.903, with a sensitivity and specificity of 73.10% and 96.90%, respectively. Last, f was positively correlated with PPH and units of RBCs transfused. DiscussionPreoperative MRI features and IVIM parameters may be used to predict poor outcomes in patients with invasive placental disorders like PAS.

Deep learning-based reconstruction enhances image quality and improves diagnosis in magnetic resonance imaging of the shoulder joint.

Accelerated magnetic resonance imaging sequences reconstructed using the vendor-provided Recon deep learning algorithm (DL-MRI) were found to be more likely than conventional magnetic resonance imaging (MRI) sequences to detect subacromial (SbA) bursal thickening. However, the extent of this thickening was not extensively explored. This study aimed to compare the image quality of DL-MRI with conventional MRI sequences reconstructed via conventional pipelines (Conventional-MRI) for shoulder examinations and evaluate the effectiveness of DL-MRI in accurately demonstrating the degree of SbA bursal and subcoracoid (SC) bursal thickening. This prospective cross-sectional study enrolled 41 patients with chronic shoulder pain who underwent 3-T MRI (including both Conventional-MRI and accelerated MRI sequences) of the shoulder between December 2022 and April 2023. Each protocol consisted of oblique axial, coronal, and sagittal images, including proton density-weighted imaging (PDWI) with fat suppression (FS) and oblique coronal T1-weighted imaging (T1WI) with FS. The image quality and degree of artifacts were assessed using a 5-point Likert scale for both Conventional-MRI and DL-MRI. Additionally, the degree of SbA and SC bursal thickening, as well as the relative signal-to-noise ratio (rSNR) and relative contrast-to-noise ratio (rCNR) were analyzed using the paired Wilcoxon test. Statistical significance was defined as P<0.05. The utilization of accelerated sequences resulted in a remarkable 54.7% reduction in total scan time. Overall, DL-MRI exhibited superior image quality scores and fewer artifacts compared to Conventional-MRI. Specifically, DL-MRI demonstrated significantly higher measurements of SC bursal thickenings in the oblique sagittal PDWI sequence compared to Conventional-MRI [3.92 (2.83, 5.82) vs. 3.74 (2.92, 5.96) mm, P=0.028]. Moreover, DL-MRI exhibited higher detection of SbA bursal thickenings in the oblique coronal PDWI sequence [2.61 (1.85, 3.46) vs. 2.48 (1.84, 3.25) mm], with a notable trend towards significant differences (P=0.071). Furthermore, the rSNRs of the muscle in DL-MRI images were significantly higher than those in Conventional-MRI images across most sequences (P<0.001). However, the rSNRs of bone on Conventional-MRI of oblique axial and oblique coronal PDWI sequences showed adverse results [oblique axial: 1.000 (1.000, 1.000) vs. 0.444 (0.367, 0.523); and oblique coronal: 1.000 (1.000, 1.000) vs. 0.460 (0.387, 0.631); all P<0.001]. Additionally, all DL-MRI images exhibited significantly greater rSNRs and rCNRs compared to accelerated MRI sequences reconstructed using traditional pipelines (P<0.001). In conclusion, the utilization of DL-MRI enhances image quality and improves diagnostic capabilities, making it a promising alternative to Conventional-MRI for shoulder imaging.

Stroke-Induced Secondary Neurodegeneration of the Corticospinal Tract-Time Course and Mechanisms Underlying Signal Changes in Conventional and Advanced Magnetic Resonance Imaging.

Secondary neurodegeneration refers to the final result of several simultaneous and sequential mechanisms leading to the loss of substance and function in brain regions connected to the site of a primary injury. Stroke is one of the most frequent primary injuries. Among the subtypes of post-stroke secondary neurodegeneration, axonal degeneration of the corticospinal tract, also known as Wallerian degeneration, is the most known, and it directly impacts motor functions, which is crucial for the motor outcome. The timing of its appearance in imaging studies is usually considered late (over 4 weeks), but some diffusion-based magnetic resonance imaging (MRI) techniques, as diffusion tensor imaging (DTI), might show alterations as early as within 7 days from the stroke. The different sequential pathological stages of secondary neurodegeneration provide an interpretation of the signal changes seen by MRI in accordance with the underlying mechanisms of axonal necrosis and repair. Depending on the employed MRI technique and on the timing of imaging, different rates and thresholds of Wallerian degeneration have been provided in the literature. In fact, three main pathological stages of Wallerian degeneration are recognizable-acute, subacute and chronic-and MRI might show different changes: respectively, hyperintensity on T2-weighted sequences with corresponding diffusion restriction (14-20 days after the injury), followed by transient hypointensity of the tract on T2-weighted sequences, and by hyperintensity and atrophy of the tract on T2-weighted sequences. This is the main reason why this review is focused on MRI signal changes underlying Wallerian degeneration. The identification of secondary neurodegeneration, and in particular Wallerian degeneration, has been proposed as a prognostic indicator for motor outcome after stroke. In this review, the main mechanisms and neuroimaging features of Wallerian degeneration in adults are addressed, focusing on the time and mechanisms of tissue damage underlying the signal changes in MRI.

Diagnostic contribution of diffusion-weighted imaging in liver hemangiomas

Objective: To evaluate the contribution of diffusion-weighted imaging (DWI) and measure apparent diffusion coefficient values (ADC) in hepatic hemangiomas.&#x0D; Material and Methods: Seventy patients with liver hemangiomas were evaluated with DWI with a b value of 800 s/mm2. ADC map was created and ADC values were measured for 70 liver masses and normal liver tissue following DWI. ADC measurements of 70 normal liver parenchyma and mean ADC values of 80 hemangiomas are performed.&#x0D; Results: Eighty hemangiomas of 70 patients (50 female and 20 male) were evaluated. The mean age of the patients was 49.61±10.96 years. Hemangiomas were most frequently demonstrated at segment 7 (%28.8), segment 6 (%21.3), and least demonstrated at segment 5 (%5). While the mean ADC measurements of normal livers were 1.06±0.11 x 10-3 mm2/sn, the mean ADC values of hemangiomas were measured as 1.70±0.29 x 10-3 mm2/sn.&#x0D; Conclusion: DWI and the ADC measurements seem to be useful for the diagnosis of liver hemangiomas. DWI should be routinely added to conventional magnetic resonance imaging sequences.

White Matter Integrity and Motor Function Disruption Due to Traumatic Brain Injury in Piglets: Impacts on Motor-Related Brain Fibers.

Pediatric traumatic brain injury (TBI) often induces significant disability in patients, including long-term motor deficits. Early detection of injury severity is key in determining a prognosis and creating appropriate intervention and rehabilitation plans. However, conventional magnetic resonance imaging (MRI) scans, such as T2 Weighted (T2W) sequences, do not reliably assess the extent of microstructural white matter injury. Diffusion tensor imaging (DTI) tractography enables three-dimensional reconstruction of specific white matter tracts throughout the brain in order to detect white matter injury based on anisotropic diffusion. The objective of this study was to employ DTI tractography to detect acute changes to white matter integrity within the intersecting fibers of key motor-related brain regions following TBI. Piglets were assigned to either the sham craniectomy group (sham; n = 6) or the controlled cortical impact TBI group (TBI; n = 6). Gait and MRI were collected at seven days post-surgery (DPS). T2W sequences confirmed a localized injury predominately in the ipsilateral hemisphere in TBI animals. TBI animals, relative to sham animals, showed an increased apparent diffusion coefficient (ADC) and decreased fractional anisotropy (FA) in fiber bundles associated with key brain regions involved in motor function. TBI animals exhibited gait deficits, including stride and step length, compared to sham animals. Together these data demonstrate acute reductions in the white matter integrity, measured by DTI tractography, of fibers intersecting key brain regions that strongly corresponded with acute motor deficits in a pediatric piglet TBI model. These results provide the foundation for the further development of DTI-based biomarkers to evaluate motor outcomes following TBI.

Feasibility of diffusion tensor imaging in cervical spondylotic myelopathy using MUSE sequence

The most frequent type of spinal cord injury is cervical spondylotic myelopathy (CSM). Conventional structural magnetic resonance imaging (MRI) is the gold diagnosis standard for CSM. Diffusion tensor imaging (DTI) could reflect microstructural changes in the spinal cord by tracing water molecular diffusion in early stages of CSM. However, due to the complex local anatomical structure and small field of view of the spinal cord, the imaging effect of traditional DTI imaging on the spinal cord is limited. MUSE (MUltiplexed Sensitivity-Encoding) -DTI is a novel diffusion weighted imaging (DWI) sequence that achieves higher signal intensity through multiple excitation acquisition. MUSE sequence may improve the quality of spinal cord DTI imaging. Prospective study. This study aimed to investigate the clinical diagnosis value of a novel protocol of MUSE-DTI in patients with cervical spondylotic myelopathy (CSM). From August 2021 to March 2022, a total of 60 subjects (22-71 years) were enrolled, including 51 CSM patients (22 males, 29 females) and 9 healthy subjects (4 males and 5 females). Each subject underwent a MUSE-DTI examination and a clinical Japanese Orthopedic Association (JOA) scale. We measured values of FA (Fractional Anisotropy), MD (Mean Diffusivity), AD (Axial Diffusivity), and RD (Radial Diffusivity), and collected the clinical JOA scores of each subject before the MR examination. A 3.0T MR scanner (Signa Architect, GE Healthcare) performed the MUSE-DTI sequence on each subject. The cervical canal stenosis of subjects was classified from grade 0 to grade Ⅲ according to the method of an MRI grading system. FA, MD, AD, and RD maps were generated by post-processing MUSE-DTI data on the GE workstation. Regions of interest (ROIs) were manually drawn at the C2 vertebral body level and C2/3-C6/7 intervertebral disc levels by covering the whole spinal cord. The clinical severity of myelopathy of subjects was assessed by the clinical Japanese Orthopedic Association scale (JOA). MUSE-DTI can acquire a high-resolution diffusion image compared to traditional DTI. The FAMCL values showed a decreasing trend from grade 0 to grade Ⅲ, while the MDMCL, ADMCL, and RDMCL values showed an overall increasing trend. Significant differences in MDMCL, ADMCL, and RDMCL values were found between adjacent groups among grades Ⅰ-Ⅲ (p<0.05). The ADC2 values in CSM patients (grade I-Ⅲ) were significantly lower than in healthy individuals (grade 0) (P=0.019). The clinical JOA score has a significant correlation with FAMCL (P=0.035), MDMCL (P<0.001), ADMCL (P<0.001), and RDMCL (P<0.001) values. MUSE-DTI displayed a better image quality compared to traditional DTI. MUSE-DTI parameters displayed a grade-dependent trend. All the MUSE-DTI parameters at MCL were correlated with the clinical JOA scores. The ADC2 values can reflect the secondary damage of distal spinal cord. Therefore, MUSE-DTI could be a reliable biomarker for clinical auxiliary diagnosis of spinal cord injury severity in cervical spondylotic myelopathy.

Differing patterns of cortical grey matter pathology identified by multifractal analysis in UMN-predominant ALS patients with and without corticospinal tract hyperintensity

The pathological hallmarks of amyotrophic lateral sclerosis (ALS) are degeneration of the primary motor cortex grey matter (GM) and corticospinal tract (CST) resulting in upper motor neuron (UMN) dysfunction. Conventional brain magnetic resonance imaging (MRI) shows abnormal CST hyperintensity in some UMN-predominant ALS patients (ALS-CST+) but not in others (ALS-CST–). In addition to the CST differences, we aimed to determine whether GM degeneration differs between ALS-CST+ and ALS-CST– patients by cortical thickness (CT), voxel-based morphometry (VBM) and fractal dimension analyses. We hypothesized that MRI multifractal (MF) measures could differentiate between neurologic controls (n = 14) and UMN-predominant ALS patients as well as between patient subgroups (ALS-CST+, n = 21 vs ALS-CST–, n = 27). No significant differences were observed in CT or GM VBM in any brain regions between patients and controls or between ALS subgroups. MF analyses were performed separately on GM of the whole brain, of frontal, parietal, occipital, and temporal lobes as well as of cerebellum. Estimating MF measures D (Q = 0), D (Q = 1), D (Q = 2), Δf, Δα of frontal lobe GM classified neurologic controls, ALS-CST+ and ALS-CST– groups with 98% accuracy and > 95% in F1, recall, precision and specificity scores. Classification accuracy was only 74% when using whole brain MF measures and < 70% for other brain lobes. We demonstrate that MF analysis can distinguish UMN-predominant ALS subgroups based on GM changes, which the more commonly used quantitative approaches of CT and VBM cannot.

Multi‑parameter quantitative magnetic resonance imaging in the early assessment of radiation‑induced parotid damage in patients with nasopharyngeal carcinoma following intensity‑modulated radiotherapy.

The present study aimed to investigate the value of intravoxel incoherent motion imaging (IVIM) and three-dimensional pulsed continuous arterial spin labeling (ASL) in assessing dynamic changes of the parotid gland in patients with nasopharyngeal carcinoma (NPC) following radiotherapy (RT). A total of 18 patients with NPC who underwent intensity-modulated RT were enrolled in the present study. All patients underwent conventional magnetic resonance imaging, plus IVIM and ASL imaging of the bilateral parotid glands within 2 weeks prior to RT, and 1 week (1W) and 3 months (3M) following RT. Pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (F) and blood flow (BF) were analyzed. D and BF values were significantly increased from pre-RT to 1W post-RT [change rate: Median (IQR), ΔD1W%: 39.28% (38.23%) and ΔBF1W%: 60.84% (54.88%)] and continued to increase from 1W post-RT to 3M post-RT [55.44% (40.56%) and ΔBF%: 120.39% (128.74%)]. In addition, the F value was significantly increased from pre-RT to 1W post-RT, [change rate: Median (IQR), ΔF1W%: 28.13% (44.66%)], and this decreased significantly from 1W post-RT to 3M post-RT. However, no significant differences were observed between pre-RT and 3M post-RT. Results of the present study also demonstrated that the D* value was significantly decreased from pre-RT to 1W post-RT and 3M post-RT [change rate: Median (IQR), ΔD*1w%: -41.86% (51.71%) and ΔD*3M: -29.11% (42.67%)]. No significant difference was observed between the different time intervals post-RT. There was a significant positive correlation between percentage change in ΔBF1W and radiation dose (ρ=0.548, P=0.001). Thus, IVIM-diffusion-weighted imaging and ASL may aid in the detection and prediction of radiation-induced parotid damage in the early stages following RT. They may contribute to further understanding the potential association between damage to the parotid glands and patient-/treatment-related variables, through the assessment of individual microcapillary perfusion and tissue diffusivity.

MRI-based Texture Analysis in Differentiation of Benign and Malignant Vertebral Compression Fractures.

The diagnosis and characterization of vertebral compression fractures are very important for clinical management. In this evaluation, which is usually performed with diagnostic (conventional) imaging, the findings are not always typical or diagnostic. Therefore, it is important to have new information to support imaging findings. Texture analysis is a method that can evaluate information contained in diagnostic images and is not visually noticeable. This study aimed to evaluate the magnetic resonance images of cases diagnosed with vertebral compression fractures by the texture analysis method, compare them with histopathological data, and investigate the effectiveness of this method in the differentiation of benign and malignant vertebral compression fractures. Fifty-five patients with a total of 56 vertebral compression fractures were included in the study. Magnetic resonance images were examined and segmented using Local Image Feature Extraction (LIFEx) software, which is an open-source program for texture analysis. The results were compared with the histopathological diagnosis. The application of the Decision Tree algorithm to the dataset yielded impressively accurate predictions (≈95% in accuracy, precision, and recall). Interpreting tissue analysis parameters together with conventional magnetic resonance imaging findings can improve the abilities of radiologists, lead to accurate diagnoses, and prevent unnecessary invasive procedures. Further prospective trials in larger populations are needed to verify the role and performance of texture analysis in patients with vertebral compression fractures.