Evaluation of salivary gland fat fraction values in patients with primary Sjögren's syndrome by mDIXON quant imaging: Initial findings

Validation of quantitative magnetic resonance imaging techniques in head and neck healthy structures involved in the salivary and swallowing function: Accuracy and repeatability

Background and Purpose

Radiation-induced damage to the organs at risk (OARs) in head-and-neck cancer (HNC) patient can result in long-term complications. Quantitative magnetic resonance imaging (qMRI) techniques such as diffusion-weighted imaging (DWI), DIXON for fat fraction (FF) estimation and T2 mapping could potentially provide a spatial assessment of such damage. The goal of this study is to validate these qMRI techniques in terms of accuracy in phantoms and repeatability in-vivo across a broad selection of healthy OARs in the HN region.

Materials and Methods

Scanning was performed at a 3 T diagnostic MRI scanner, including the calculation of apparent diffusion coefficient (ADC) from DWI, FF and T2 maps. Phantoms were scanned to estimate the qMRI techniques bias using Bland-Altman statistics. Twenty-six healthy subjects were scanned twice in a test-retest study to determine repeatability. Repeatability coefficients (RC) were calculated for the parotid, submandibular, sublingual and tubarial salivary glands, oral cavity, pharyngeal constrictor muscle and brainstem. Additionally, a linear mixed-effect model analysis was used to evaluate the effect of subject-specific characteristics on the qMRI values.

Results

Bias was 0.009x10-3 mm2/s for ADC, -0.7 % for FF and -7.9 ms for T2. RCs ranged 0.11-0.25x10-3 mm2/s for ADC, 1.2-6.3 % for FF and 2.5-6.3 ms for T2. A significant positive linear relationship between age and the FF and T2 for some of the OARs was found.

Conclusion

These qMRI techniques are feasible, accurate and repeatable, which is promising for treatment response monitoring and/or differentiating between healthy and unhealthy tissues due to radiation-induced damage in HNC patients.

Correlation between degeneration of cervical intervertebral disc and degeneration of paravertebral muscle

Objective

To investigate the relationship between degeneration of cervical intervertebral disc and degeneration of paravertebral muscles[multifidus (MF), cervical semispinalis (SCer), semispinalis capitis (SCap) and splenius capitis (SPL)].

Methods

82 patients with chronic neck pain were randomly selected, including 43 males and 39 females, with 50.73 0.7.51 years old. All patients were scanned by 3.0T MRI Philips Ingenia performed conventional MRI sequence scanning and fat measurement sequence mDIXON-Quant scanning of cervical. Fat infiltration (FI) and cross-sectional area (CSA) of cervical paravertebral muscle (MF, SCer, SCap and SPL) at central level of C5-6 disc were measured by Philips 3.0T MRI image post-processing workstation. According to Pfirrmann grading system, there was no grade I in the included cases. The number of grade IIr IV cases were n=16, 40, 19 and 7 respectively. CSA and FI of cervical paravertebral muscles were compared with t test or one-way ANOVA, Spearman correlation analysis was used to evaluate the correlation between age, disc degeneration, and CSA, FI of cervical paravertebral muscles, and multiple linear regression analysis was used to analyze the independent influencing factors of CSA and FI.

Results

CSA of cervical paravertebral muscles in male patients was significantly higher than that in female patients (all P<0.001), but there was no significant difference in FI (all P>0.05). Age was weakly correlated with CSA of MF+SCer, moderately correlated with CSA of SCap and SPL (r=-0.256, -0.355 and -0.361, P<0.05), weakly correlated with FI of SCap and SPL (r= 0.182 and 0.264, P<0.001), moderately correlated with FI of MF+SCer (r=0.408, P<0.001). There were significant differences in FI with disc degeneration (P<0.001, P=0.028 and P=0.005). Further correlation analysis showed that disc degeneration was strongly correlated with FI of MF+SCer (r=0.629, P<0.001), and moderately correlated with FI of SCap and SPL (r=0.363, P=0.001; r=0.345, P=0.002). Multiple linear regression analysis showed that sex and age were the influencing factors of CSA of SCap and SPL, sex was the independent influencing factor of CSA of MF+SCer, and disc degeneration was the independent influencing factor of FI.

Conclusions

Age is negatively correlated with CSA and positively correlated with FI. Disc degeneration was correlated with FI of paravertebral muscles, especially with FI of MF and SCer. Sex and age were the influencing factors of CSA, while disc degeneration was the independent influencing factor of FI.

The value of MRI-based radiomics for evaluating early parotid gland injury in primary Sjögren's syndrome

OBJECTIVE

This study aimed to evaluate the value of machine learning models (ML) based on MRI radiomics in diagnosing early parotid gland injury in primary Sjögren's syndrome (pSS).

METHODS

A total of 164 patients (114 in the training cohort and 50 in the testing cohort) with pSS (n=82) or healthy controls (HC) (n=82) were enrolled. Itksnap software was used to perform two-dimensional segmentation of the bilateral parotid glands on T1-weighted (T1WI) and fat-suppressed T2-weighted imaging (fs-T2WI) images. A total of 1548 texture features of the parotid glands were extracted using radiomics software. A radiomics score (Radscore) was constructed and calculated. A t-test was used to compare the Radscore between the two groups. Finally, five machine learning models were trained and tested to identify early pSS parotid injury, and the performance of the machine learning models was evaluated by calculating the acceptance operating curve (ROC) and other parameters.

RESULTS

The Radscores between the pSS and HC groups showed significant statistical differences (p<0.001). Among the five machine learning models, the Extra Trees Classifier (ETC) model performed high predictive efficacy in identifying early pSS parotid injury, with an AUC of 0.87 in the testing set.

CONCLUSION

MRI radiomics-based machine learning models can effectively diagnose early parotid gland injury in primary Sjögren's syndrome.

Chemical shift-encoded MRI with compressed sensing combined with parallel imaging for proton density fat fraction measurement of the lumbar vertebral bone marrow

We aimed to investigate the accuracy of proton density fat fraction (PDFF) measurement of the lumbar vertebral bone marrow using chemical shift-encoded magnetic resonance imaging (CSE-MRI) with compressed sensing combined with parallel imaging (CSPI). This study recruited a commercially available phantom, and 43 patients. Fully sampled data without CSPI and under-sampled data with CSPI acceleration factors of 2.4, 3.6, and 4.8 were acquired using a 1.5T imaging system. The relationships between PDFF measurements obtained with the no-CSPI acquisition and those obtained with each CSPI acquisition were assessed using Pearson correlation coefficient (r), linear regression analyses, and Bland-Altman analysis. The intra- and inter-observer variabilities of the PDFF measurements were evaluated using the intraclass correlation coefficient. PDFF measurements obtained with all acquisitions showed a significant correlation and strong agreement with the reference PDFF measurement of the phantom. PDFF measurements obtained using CSE-MRI with and without CSPI were positively correlated (all acquisitions: r = 0.99; P < .001). The mean bias was -0.31% to -0.17% with 95% limits of agreement within ±2.02%. The intra- and inter-observer agreements were excellent (intraclass correlation coefficient: 0.988 and 0.981, respectively). A strong agreement and positive correlation were observed between the PDFF measurements obtained using CSE-MRI with and without CSPI. PDFF measurement of the lumbar vertebral bone marrow using CSE-MRI with CSPI can be acquired with a maximum reduction of approximately 75% in the acquisition time compared with a fully sampled acquisition.

Evaluation of renal function in chronic kidney disease (CKD) by mDIXON-Quant and Amide Proton Transfer weighted (APTw) imaging

BACKGROUND

Chronic kidney disease (CKD) is a long-term condition that affects >10% of the adult population worldwide. Noninvasive assessment of renal function has important clinical significance for disease diagnosis and prognosis evaluation.

OBJECTIVE

To explore the value of mDIXON-Quant combined with amide proton transfer weighted (APTw) imaging for accessing renal function in chronic kidney disease (CKD).

MATERIALS AND METHODS

Twenty-two healthy volunteers (HVs) and 30 CKD patients were included in this study, and the CKD patients were divided into the mild CKD (mCKD) group (14 cases) and moderate-to-severe CKD (msCKD) group (16 cases) according to glomerular filtration rate (eGFR). The cortex APT (cAPT), medulla APT (mAPT), cortex R2⁎ (cR2⁎), medulla R2⁎ (mR2⁎), cortex FF (cFF) and medulla FF (mFF) values of the right renal were independently measured by two radiologists. Intra-group correlation coefficient (ICC) test was used to test the inter-observer consistency. The analysis of variance (ANOVA) was used to compare the difference among three groups. Mann-Whitney U test was used to analyze the differences of R2⁎, FF and APT values among the patient and HV groups. Area under the receiver operating characteristic (ROC) curve (AUC) was used to analyze the diagnostic efficiency. The corresponding threshold, sensitivity, and specificity were obtained according to the maximum approximate index. The combined diagnostic efficacy of R2⁎, FF, and APT values was analyzed by binary Logistic regression, and the AUC of combined diagnosis was compared with the AUC of the single parameter by the Delong test.

RESULTS

The cAPT value of the HV, mCKD and msCKD groups increased gradually. The mAPT value and cR2⁎ values of the mCKD and msCKD groups were higher than those of the HV group, while the mFF value of the mCKD group was lower than HV group (all P < 0.05). The cAPT and mAPT values showed good diagnostic efficacy in evaluating different degrees of renal damage, while cR2⁎ and mFF values showed moderate diagnostic efficacy. When combining the APT, R2⁎, and FF values, the diagnostic efficiency was significantly improved.

CONCLUSION

mDIXON-Quant combined APTw imaging can be used for improved diagnosis of CKD.

PPARs/macrophages: A bridge between the inflammatory response and lipid metabolism in autoimmune diseases

Autoimmune diseases (AIDs) are a collection of pathologies that arise from autoimmune reactions and lead to the destruction and damage of the body's tissues and cellular components, ultimately resulting in tissue damage and organ dysfunction. The anti-inflammatory effects of the peroxisome proliferator-activated receptor (PPAR), a pivotal regulator of lipid metabolism, are crucial in the context of AIDs. PPAR mitigates AIDs by modulating macrophage polarization and suppressing the inflammatory response. Numerous studies have demonstrated the crucial involvement of lipid metabolism and phenotypic switching in classically activated (M1)/alternatively activated (M2)-like macrophages in the inflammatory pathway of AIDs. However, the precise mechanism by which PPAR, a critical mediator between of lipid metabolism and macrophage polarization, regulates macrophage polarization remains unclear. This review aimed to clarify the role of PPAR and macrophages in the triangular relationship among AIDs, lipid metabolism, and inflammatory response, and aims to summarize the mechanism of the PPAR-mediated macrophage activation and polarization, which impacts the progression and development of AIDs.

mDIXON-Quant for differentiation of renal damage degree in patients with chronic kidney disease

Background

Chronic kidney disease (CKD) is a complex syndrome with high morbidity and slow progression. Early stages of CKD are asymptomatic and lack of awareness at this stage allows CKD to progress through to advanced stages. Early detection of CKD is critical for the early intervention and prognosis improvement.

Purpose

To assess the capability of mDIXON-Quant imaging to detect early CKD and evaluate the degree of renal damage in patients with CKD.

Study type

Retrospective.

Population

35 patients with CKD: 18 cases were classifified as the mild renal damage group (group A) and 17 cases were classifified as the moderate to severe renal damage group (group B). 22 healthy volunteers (group C).

Field strength/sequence

A 3.0 T/T1WI, T2WI and mDIXON-Quant sequences.

Assessment

Transverse relaxation rate (R2*) values and fat fraction (FF) values derived from the mDIXON-Quant were calculated and compared among the three groups.

Statistical tests

The intra-class correlation (ICC) test; Chi-square test or Fisher's exact test; Shapiro-Wilk test; Kruskal Wallis test with adjustments for multiplicity (Bonferroni test); Area under the receiver operating characteristic (ROC) curve (AUC). The significance threshold was set at P < 0.05.

Results

Cortex FF values and cortex R2* values were significantly different among the three groups (P=0.028, <0.001), while medulla R2* values and medulla FF values were not (P=0.110, 0.139). Cortex FF values of group B was significantly higher than that of group A (Bonferroni adjusted P = 0.027). Cortex R2* values of group A and group B were both significantly higher than that of group C (Bonferroni adjusted P = 0.012, 0.001). The AUC of cortex FF values in distinguishing group A and group B was 0.766. The diagnostic efficiency of cortex R2* values in distinguishing group A vs. group C and group B vs. group C were 0.788 and 0.829.

Conclusion

The mDIXON-Quant imaging had a potential clinical value in early diagnosis of CKD and assessing the degree of renal damage in CKD patients.