Iterative Decomposition Of Water Research Articles

Pre-Operative Quantitative MRI-Based Rotator Cuff Muscle Fat Fractions Are Associated with Patient-Reported Outcomes Following Rotator Cuff Repair

Objectives: Advanced fatty infiltration is correlated with poor outcomes after rotator cuff repair, and high-grade fatty infiltration is considered a contraindication for repair. The influence of lower levels of fatty infiltration on outcomes after rotator cuff repair remains unclear. Quantitative magnetic resonance (MR) imaging sequences, specifically IDEAL imaging (iterative decomposition of water and fat with echo asymmetry and least-squares estimation), has been recently applied to measuring fatty infiltration of the rotator cuff muscles. Our purpose was to evaluate the relationship between rotator cuff intramuscular fat and patient-reported outcome measures after rotator cuff repair. We hypothesized that higher pre-operative fat content would be negatively correlated with post-operative outcomes. Methods: We retrospectively identified patients who underwent arthroscopic rotator cuff repair with pre-operative MRI scan with sagittal-oblique IDEAL imaging. All procedures were approved by our Institutional Review Board. Pre-operative tear size, tendon involvement, and tendon retraction were measured by a musculoskeletal radiologist. Image segmentation was performed manually on four consecutive slices with perimuscular fat excluded. Patients completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity computer adapted survey at a minimum of two years after repair. Correlations between intramuscular fat measurements and PROMIS scores were determined with Spearman’s rank correlation coefficient. Patients were grouped by PROMIS scores above and below 50, as 50 represents population mean. Mann-Whitney U tests were used to compare fat fractions between patients with high PROMIS scores (at or above 50) or low PROMIS scores (less than 50). Multivariate linear regression was performed with PROMIS score as the dependent variable, and individual muscle fat fractions, age, BMI, sex, and total tear size as independent predictors. Significance was defined as p<0.05. Results: A total of 80 patients were included (Table 1). Mean follow-up was 42.5 ±10.7 months. Post-operative PROMIS scores were significantly correlated with the infraspinatus fat fraction (rho = -0.25, p = 0.02) and subscapularis fat fraction (rho = -0.29, p = 0.009). The infraspinatus fat fraction for patients with a low PROMIS score (N=31) was significantly higher relative to those with a PROMIS score above 50 (N=49) (7.2±4.9% vs. 5.2 ±3.0%; p=0.046) (Figure 1). The subscapularis fat fraction was significantly higher for patients with a low PROMIS score relative to those with a PROMIS score above 50 (10.4 ±5.1% vs. 8.2 ±5.0%; p=0.001). In controlling for age, BMI, sex, and total tear size, multivariate regression modeling identified infraspinatus fat fraction (beta = -0.68, p = 0.029) as the only significant independent predictor of post-operative PROMIS score. Conclusion: We observed significant relationships between infraspinatus and subscapularis muscle quality and post-operative patient-reported outcomes after rotator cuff repair. Infraspinatus fat fraction was the only significant predictor when accounting for demographics and rotator cuff tear size. Importantly, these patients were selected for rotator cuff repair and therefore excluded patients with advanced fatty infiltration. Even in patients with lower degrees of muscle degeneration, small differences in muscle quality may impact outcomes after tendon repair. [Table: see text][Figure: see text]

Self‐adapting multi‐peak water‐fat reconstruction for the removal of lipid artifacts in chemical exchange saturation transfer (CEST) imaging

Artifacts caused by strong lipid signals pose challenges in body chemical exchange saturation transfer (CEST) imaging. This study aimed to develop an accurate water-fat reconstruction method based on the multi-echo Dixon technique to remove lipid artifacts in CEST imaging. It is well known that fat has multiple spectral peaks. Furthermore, RF pulses in CEST preparation saturate each fat peak at different levels, complicating fat modeling. Therefore, a self-adapting multi-peak model (SMPM) is proposed to update relative amplitudes of fat peaks using numerical calculation. With the SMPM-based updating, nonlinear least-squares fitting combined with IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation) algorithms was used for water-fat reconstruction and B0 mapping. The proposed method was compared with the reported 3-point Dixon method and the fixed multi-peak model in a phantom study using a fat-free Z-spectrum obtained from MR spectroscopy acquisition as the ground truth. This method was also validated by in vivo experiments on human breast. In the phantom experiments, the Z-spectrum from the SMPM-based method agreed well with the fat-free Z-spectrum from CEST-PRESS (point-resolved spectroscopy), validating the effective removal of lipid artifacts, while a decrease or a rise that appeared at -3.5 ppm was observed in the Z-spectrum from the 3-point method and the FMPM-based method, respectively. In the in vivo experiments, no lipid artifacts were observed in the Z-spectrum or the amide CEST map from the SMPM-based method in the fibro-glandular region of the breast with high fat fractions. The SMPM-based method successfully removes lipid artifacts and significantly improves the accuracy of CEST contrast.

Prediction of type 2 diabetes mellitus using noninvasive MRI quantitation of visceral abdominal adiposity tissue volume.

The correlation between visceral adipose tissue volume (VATV), hepatic proton-density fat fraction (PDFF), and pancreatic PDFF has been previously studied to predict the presence of type 2 diabetes mellitus (T2DM). This study investigated VATV quantitation in patients with T2DM, prediabetes, and normal glucose tolerance (NGT) using MRI to assess the roles of VATV, hepatic, and pancreatic PDFF in predicting the presence of T2DM. Forty-eight patients with a new clinical diagnosis of T2DM (n=15), prediabetes (n=17), or NGT (n=16) were included and underwent abdominal magnetic resonance imaging (MRI) scanning with the iterative decomposition of water and fat with echo asymmetry and least square estimation image quantification (IDEAL-IQ) sequencing. VATV was obtained at the level of the 2nd and 3rd lumbar vertebral bodies (VATV L2 and VATV L3) where the sum of VATV L2 and VATV L3 (total VATV) were computed, respectively. Also, pancreatic and hepatic fat content was quantified by measuring the PDFF. The receiver operating characteristic (ROC) curve and binary logistics regression model analysis were employed to evaluate their ability to predict the presence of T2DM. The VATV L2, VATV L3, and total VATV values of the T2DM group were significantly higher than the prediabetes and NGT groups (P<0.05). There was no statistically significant difference between the values of VATV L2, VATV L3, and total VATV between the prediabetes and NGT groups (P>0.05). The ROC curve showed the areas under the curve for VATV L2, VATV L3, total VATV, hepatic PDFF, and pancreatic PDFF were 0.76, 0.80, 0.80, 0.79, and 0.75, respectively, in predicting the presence of T2DM (P<0.01). The ROC curves of VATV L2, VATV L3, total VATV, hepatic PDFF, and pancreatic PDFF failed to predict the presence of prediabetes and NGT (P>0.05). The binary logistics regression model analysis revealed that only VATV L3 was independently associated with the incidence of T2DM (P=0.01 and OR =1.01). The sensitivity, specificity, and total accuracy were 80.00%, 88.20%, and 84.40%, respectively. Compared with hepatic PDFF, pancreatic PDFF, VAVT L2, and total VATV, VAVT L3 was the better predictor of T2DM.

Quantification of fat content of lower limbs using iterative decomposition of water and fat with asymmetry and least squares estimation-quantitative fat imaging in Duchenne muscular dystrophy

Objective To evaluate the fatty infiltration of lower limbs (pelvis, thighs and calf) by using iterative decomposition of water and fat with asymmetry and least squares estimation-quantitative fat imaging (IDEAL-IQ) in Duchenne muscular dystrophy (DMD) patients, and correlate muscle fat fraction(FF) with clinical assessments. Methods The prospective study method was applied, twenty-one patients with DMD were diagnosed by genetic analysis and/or muscle biopsy and twenty-one age-matched healthy control subjects, were evaluated using IDEAL-IQ, calculating fat fraction (FF) of muscles in the lower limbs. The clinical data of patients, such as age, height, weight, course of disease, time to walk 10 m, Medical Research Council Scale score, were collected. The age and height between DMD group and control group were compared by independent sample t test. The weight, BMI and FF values between two groups were compared by independent samples nonparametric tests (Mann-Whitney U tests). K related samples nonparametric test (Friedman test) was used for comparison of FF values between pelvic muscles, thighs muscles and calf muscles. The relationships between FF values and clinical assessments were investigated using Spearman correlation test. Results The mean FF of pelvic muscles [13.1(6.9, 33.8)] was significantly higher than that of the thighs muscles [8.3 (23.4, 4.5)] and calf muscles [8.3 (23.4, 4.5)] (all P<0.05) in DMD group. The FF of all the pelvic muscles in DMD were significantly higher than that of the control group muscles (all P<0.05). The gluteus maximus had the greatest mean FF values [34.7 (26.4, 63.7)] in pelvic muscles. The FF of all the thigh muscles in DMD were significantly higher than that of the control group muscles, except for the sartorius, adductor longus and gracilis (Z=0.69, 1.67 and 1.22, respectively, P=0.489, 0.094 and 0.222, respectively). The adductor magnus had the greatest mean FF values [27.2 (12.4, 58.5)] in thigh muscles. The FF of all the calf muscles in DMD were significantly higher than that of the control group muscles, except for the tibialis anterior and tibialis posterior (Z value was1.77 and 1.85, respectively, P value was 0.076 and 0.064, respectively). The gastrocnemius lateral had the greatest mean FF values [7.4 (4.6, 20.9)] in calf muscles. The mean FF value of pelvic muscles (r=0.679, 0.704, −0.761, 0.755, respectively, all P<0.001), thighs muscles (r=0.801, 0.813, −0.738, 0.706, respectively, all P<0.001) and calf muscles (r=0.502, 0.682, −0.637, 0.664, respectively, all P<0.05) were significantly correlate with age, course of disease, %MRC and time to walk 10 m. Conclusions The fat infiltration of lower limbs in DMD patients showes a distinct involvement pattern. IDEAL-IQ technique is able to quantitatively and objectively evaluate the degree of fat infiltration of lower limbs in DMD, and it has great value in clinical application. Key words: Muscular dystrophies; Magnetic resonance imaging; Muscle, skeletal

41. A Comparative Evaluation of MRI and Liver Biopsy for Liver Fat Estimation in Liver Transplant Donors

Background and Aims: Donor hepatic steatosis is associated with a greater risk of complications after living donor liver transplantation (LDLT). MRI IDEAL IQ (Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation) has recently been shown to be accurate for hepatic fat quantification in animal and human studies. In this study, we describe the use of MRI IDEAL IQ technique in quantification of hepatic steatosis in live liver donors and compared it with liver biopsy. Methods: Between November 2014 to February 2017 we prospectively evaluated 50 liver donors comparing the MRI IDEAL IQ technique with either preoperative or intraoperative liver biopsy. The accuracy of MRI was assessed by linear regression analysis between MRI liver fat fraction and biopsy fat estimation. Results: Less than 3% fat content was detected in 33 donors (84.6%), 3–6% fat content in 13 (26%), 6–9% fat content in 3 (6%) and more than 9% fat content in 1 donor (2%) on MRI. On linear regression analysis MRI IDEAL IQ fat evaluation correlated well with histopathological fat evaluation for detecting fat content in livers (R2 = 0.757). The accuracy of MRI IDEAL IQ was 88% with sensitivity and specificity rates of 100% and 84.6% respectively for detecting fat content in the liver (P < 0.0001). The average liver fat content evaluated by MRI correlated with BMI but not with age or sex. The groups were comparable in terms of demographic and clinical variables in donors, or development of early graft dysfunction and deranged kidney function in liver transplant recipients. Conclusions: The MRI IDEAL IQ technique is a highly reliable and accurate method, which can replace liver biopsy for the liver fat estimation in live liver donors and hence avoid potential complications of an invasive biopsy. The authors have none to declare.

Automated and accurate quantification of subcutaneous and visceral adipose tissue from magnetic resonance imaging based on machine learning

Accurate measuring of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) is vital for the research of many diseases. The localization and quantification of SAT and VAT by computed tomography (CT) expose patients to harmful ionizing radiation. Magnetic resonance imaging (MRI) is a safe and painless test. The aim of this paper is to explore a practical method for the segmentation of SAT and VAT based on the iterative decomposition of water and fat with echo asymmetry and least square estimation‑iron quantification (IDEAL-IQ) technology and machine learning. The approach involves two main steps. First, a deep network is designed to segment the inner and outer boundaries of SAT in fat images and the peritoneal cavity contour in water images. Second, after mapping the peritoneal cavity contour onto the fat images, the assumption-free K-means++ with a Markov chain Monte Carlo (AFK-MC2) clustering method is used to obtain the VAT content. An MRI data set from 75 subjects is utilized to construct and evaluate the new strategy. The Dice coefficients for the SAT and VAT content obtained from the proposed method and the manual measurements performed by experts are 0.96 and 0.97, respectively. The experimental results indicate that the proposed method and the manual measurements exhibit high reliability.

Robust water-fat separation for multi-echo gradient-recalled echo sequence using convolutional neural network.

To accurately separate water and fat signals for bipolar multi-echo gradient-recalled echo sequence using a convolutional neural network (CNN). A CNN architecture was designed and trained using the relationship between multi-echo images from the bipolar multi-echo gradient-recalled echo sequence and artifact-free water-fat-separated images. The artifact-free water-fat-separated images for training the CNN were obtained from multiple signals with different TEs by using iterative decomposition of water and fat with echo asymmetry and the least-squares estimation method, in which multiple signals at different TEs were acquired using a single-echo gradient-recalled echo sequence. We also proposed a data augmentation method using a synthetic field inhomogeneity to generate multi-echo signals, including various bipolar multi-echo gradient-recalled echo artifacts so that the CNN could prevent overfitting and increase the separation accuracy. We trained the CNN using in vivo knee images and tested it using in vivo knee, head, and ankle images. In vivo imaging results showed that the proposed CNN could separate water-fat images accurately. Although the proposed CNN was trained using only in vivo knee images, the proposed CNN could also separate water-fat images of different imaging regions. The proposed data augmentation method could prevent overfitting even with a limited number of training data sets and make the method robust to magnetic field inhomogeneities. The proposed CNN could obtain water-fat-separated images from the multi-echo images acquired from the bipolar multi-echo gradient-recalled echo sequence, which included artifacts from the bipolar gradients.

Associations between vertebral body fat fraction and intervertebral disc biochemical composition as assessed by quantitative MRI.

There is an interplay between the intervertebral disc (IVD) and the adjacent bone marrow that may play a role in the development of IVD degeneration and might influence chronic lower back pain (CLBP). To apply novel quantitative MRI techniques to assess the relationship between vertebral bone marrow fat (BMF) and biochemical changes in the adjacent IVD. Prospective. Forty-six subjects (26 female and 20 male) with a mean age of 47.3 ± 12.0 years. 3 T MRI; a combined T1ρ and T2 mapping pulse sequence and a 3D spoiled gradient recalled sequence with six echoes and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) reconstruction algorithm. Using quantitative MRI, the vertebral BMF fraction was measured as well as the biochemical composition (proteoglycan and collagen content) of the IVD. Furthermore, clinical Pfirrmann grading, Oswestry disability index (ODI), and visual analog scale (VAS) was assessed. Mixed random effects models accounting for multiple measurements per subject were used to assess the relationships between disc measurements and BMF. The relationships between BMF (mean) and T1ρ /T2 (mean and SD) were significant, with P < 0.05. Significant associations (P < 0.001) were found between clinical scores (Pfirrmann, ODI, and VAS) with T1ρ /T2 (mean and SD). BMF mean was significantly related to ODI (P = 0.037) and VAS (P = 0.043), but not with Pfirrmann (P = 0.451). In contrast, BMF SD was significantly related to Pfirrmann (P = 0.000) but not to ODI (P = 0.064) and VAS (P = 0.13). Our study demonstrates significant associations between BMF and biochemical changes in the adjacent IVD, both assessed by quantitative MRI; this may suggest that the conversion of hematopoietic bone marrow to fatty bone marrow impairs the supply of available nutrients to cells in the IVD and may thereby accelerate disc degeneration. 2 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:1219-1226.

Magnetic resonance imaging of the time course of hyperpolarized 129Xe gas exchange in the human lungs and heart

PurposeTo perform magnetic resonance imaging (MRI), human lung imaging, and quantification of the gas-transfer dynamics of hyperpolarized xenon-129 (HPX) from the alveoli into the blood plasma.Materials and methodsHPX MRI with iterative decomposition of water and fat with echo asymmetry and least-square estimation (IDEAL) approach were used with multi-interleaved spiral k-space sampling to obtain HPX gas and dissolved phase images. IDEAL time-series images were then obtained from ten subjects including six normal subjects and four patients with pulmonary emphysema to test the feasibility of the proposed technique for capturing xenon-129 gas-transfer dynamics (XGTD). The dynamics of xenon gas diffusion over the entire lung was also investigated by measuring the signal intensity variations between three regions of interest, including the left and right lungs and the heart using Welch’s t test.ResultsThe technique enabled the acquisition of HPX gas and dissolved phase compartment images in a single breath-hold interval of 8 s. The y-intersect of the XGTD curves were also found to be statistically lower in the patients with lung emphysema than in the healthy group (p < 0.05).ConclusionThis time-series IDEAL technique enables the visualization and quantification of inhaled xenon from the alveoli to the left ventricle with a clinical gradient strength magnet during a single breath-hold, in healthy and diseased lungs.Key Points• The proposed hyperpolarized xenon-129 gas and dissolved magnetic resonance imaging technique can provide regional and temporal measurements of xenon-129 gas-transfer dynamics.• Quantitative measurement of xenon-129 gas-transfer dynamics from the alveolar to the heart was demonstrated in normal subjects and pulmonary emphysema.• Comparison of gas-transfer dynamics in normal subjects and pulmonary emphysema showed that the proposed technique appears sensitive to changes affecting the alveoli, pulmonary interstitium, and capillaries.

Effect of laterality, gender, age and body mass index on the fat fraction of salivary glands in healthy volunteers: assessed using iterative decomposition of water and fat with echo asymmetry and least-squares estimation method.

To evaluate the effect of laterality, gender, age and body mass index (BMI) on fat fraction (FF) measurements of both parotid glands (PGs) and submandibular glands (SMGs) by using: Iterative decomposition of water and fat with echo asymmetry and least-squares estimation method (IDEAL-IQ). A total of 87 healthy participants were enrolled in our study. IDEAL-IQ image was scanned using a 3.0 T scanner. Paired t test was performed to compare the difference on FF of both PGs and SMGs between left and right side. The FF of two glands between male and female healthy participants were compared using an unpaired t-test. The correlation between the FF of two glands and participant age or BMI were analyzed by Pearson's correlation. Excellent inter- and intrareader agreements were obtained during the measurements of FF by IDEAL-IQ method (ICC, 0.952-0.981). FF values correlated positively with the age and BMI in both left and right PGs and SMGs (p < 0.05). No significant difference was found on FF between left and right PGs and SMGs (p > 0.05). There was also no difference on FF between male and female healthy participants (p > 0.05). FFs of PGs and SMGs were age- and BMI- dependent, but not laterality- and gender-dependent. The effect of age and BMI need to be considered in further studies using Ideal-IQ technology to evaluate FFs of salivary gland diseases.

Diagnostic value of imaging examinations in patients with primary hepatocellular carcinoma.

Primary hepatocellular carcinoma (PHC) includes hepatocellular carcinoma, intrahepatic cholangiocarcinoma and other pathological types and is characterized by rapid progression. Most of the clinical diagnoses are made at late stage or when distant metastasis occurs, increasing the difficulty of treatment and resulting in a poor prognosis. Therefore, the early diagnosis of PHC plays an important role in timely treatment and the improvement of prognosis. The gold standard for the diagnosis of primary liver cancer is liver biopsy, but it has limitations as an invasive examination. Presently, imaging has become the first choice for the diagnosis of liver cancer. We here summarize the new methods and techniques of imaging in diagnosis and evaluation of primary liver cancer in recent years, including ultrasonography, computed tomography perfusion imaging, diffusion-weighted imaging technology-voxel incoherent motion, diffusion tensor imaging, iterative decomposition of water and fat with echo asymmetry and least squares estimation-iron quantification, dynamic enhanced magnetic resonance imaging and hepatocyte-specific contrast medium imaging. Imaging diagnosis can not only evaluate the degree of differentiation, blood supply and perfusion, and invasiveness of the lesion, but also predict the prognosis, evaluate liver function, and provide references for clinical diagnosis and treatment.

Extraocular muscle sampled volume in Graves' orbitopathy using 3-T fast spin-echo MRI with iterative decomposition of water and fat sequences.

BackgroundCurrent magnetic resonance imaging (MRI) techniques for measuring extraocular muscle (EOM) volume enlargement are not ideally suited for routine follow-up of Graves’ ophthalmopathy (GO) because the difficulty of segmenting the muscles at the tendon insertion complicates and lengthens the study protocol.PurposeTo measure the EOM sampled volume (SV) and assess its correlation with proptosis.Material and MethodsA total of 37 patients with newly diagnosed GO underwent 3-T MRI scanning with iterative decomposition of water and fat (IDEAL) sequences with and without contrast enhancement. In each patient, the three largest contiguous coronal cross-sectional areas (CSA) on the EOM slices were segmented using a polygon selection tool and then summed to compute the EOM-SV. Proptosis was evaluated with the Hertel index (HI). The relationships between the HI value and EOM-SV and between HI and EOM-CSA were compared and assessed with Pearson’s correlation coefficient and the univariate regression coefficient. Inter-observer and intra-observer variability were calculated.ResultsHI showed a stronger correlation with EOM-SV (P < 0.001; r = 0.712, r2 = 0.507) than with EOM-CSA (P < 0.001; r = 0.645 and r2 = 0.329). The intraclass correlation coefficient indicated that the inter-observer agreement was high (0.998). The standard deviation between repeated measurements was 1.9–5.3%.ConclusionIDEAL sequences allow for the measurement EOM-SV both on non-contrast and contrast-enhanced scans. EOM-SV predicts proptosis more accurately than does EOM-CSA. The measurement of EOM-SV is practical and reproducible. EOM-SV changes of 3.5–8.3% can be assumed to reflect true volume changes.

Can unenhanced MRI of the breast replace contrast-enhanced MRI in assessing response to neoadjuvant chemotherapy?

The goals of neoadjuvant chemotherapy (NAC) are to reduce tumor volume and to offer a prognostic indicator in assessing treatment response. Contrast-enhanced magnetic resonance imaging (CE-MRI) is an established method for evaluating response to NAC in patients with breast cancer. To validate the role of unenhanced MRI (ue-MRI) compared to CE-MRI for assessing response to NAC in women with breast cancer. Seventy-one patients with ongoing NAC for breast cancer underwent MRI before, during, and at the end of NAC. Ue-MRI was performed with T2-weighted sequences with iterative decomposition of water and fat and diffusion-weighted sequences. CE-MRI was performed using three-dimensional T1-weighted sequences before and after administration of gadobenate dimeglumine. Two blinded observers rated ue-MRI and CE-MRI for the evaluation of tumor response. Statistical analysis was performed to compare lesion size and ADC values changes during therapy, as well as inter-observer agreement. There were no statistically significant differences between ue-MRI and CE-MRI sequences for evaluation of lesion size at baseline and after every cycle of treatment ( P > 0.05). The mean tumor ADC values at baseline and across the cycles of NAC were significantly different for the responder group. Ue-MRI can achieve similar results to CE-MRI for the assessment of tumor response to NAC. ADC values can differentiate responders from non-responders.

In Vivo Assessment of Neurodegeneration in Type C Niemann-Pick Disease by IDEAL-IQ.

ObjectiveTo noninvasively assess the neurodegenerative changes in the brain of patients with Niemann-Pick type C (NPC) disease by measuring the lesion tissue with the iterative decomposition of water and fat with echo asymmetry and least square estimation-iron quantification (IDEAL-IQ).Materials and MethodsRoutine brain MRI, IDEAL-IQ and 1H-proton magnetic resonance spectroscopy (1H-MRS, served as control) were performed on 12 patients with type C Niemann-Pick disease (4 males and 8 females; age range, 15–61 years; mean age, 36 years) and 20 healthy subjects (10 males and 10 females; age range, 20–65 years; mean age, 38 years). The regions with lesion and the normal appearing regions (NARs) of patients were measured and analyzed based on the fat/water signal intensity on IDEAL-IQ and the lipid peak on 1H-MRS.ResultsNiemann-Pick type C patients showed a higher fat/water signal intensity ratio with IDEAL-IQ on T2 hyperintensity lesions and NARs (3.7–4.9%, p < 0.05 and 1.8–3.0%, p < 0.05, respectively), as compared to healthy controls (HCs) (1.2–2.3%). After treatment, the fat/water signal intensity ratio decreased (2.2–3.4%), but remained higher than in the HCs (p < 0.05). The results of the 1H-MRS measurements showed increased lipid peaks in the same lesion regions, and the micro-lipid storage disorder of NARs in NPC patients was detectable by IDEAL-IQ instead of 1H-MRS.ConclusionThe findings of this study suggested that IDEAL-IQ may be useful as a noninvasive and objective method in the evaluation of patients with NPC; additionally, IDEAL-IQ can be used to quantitatively measure the brain parenchymal adipose content and monitor patient follow-up after treatment of NPC.

The potential role of IDEAL MRI for identification of lipids and hemorrhage in carotid artery plaques

Hemorrhage and lipid deposits contribute to instability in atherosclerotic plaques. Unstable carotid artery plaques can lead to cerebral ischemic events. While MRI studies have shown the ability to identify plaque components, the identification of hemorrhage and lipids has proven to be problematic. The purpose of this study was to quantitatively evaluate the potential of the MRI fat/water separation method known as iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) to complement and improve existing methods for the identification of hemorrhage and lipids in carotid artery plaques.Fifteen asymptomatic subjects with 50–79% stenosis of at least one carotid artery were enrolled. Hemorrhage and lipid components within carotid plaques were identified using previously published criteria based on the multiple contrast-weighted (MCW) method (3D Time-of-Flight (3D-TOF), T1-Weighted (T1W) and T2-Weighted (T2W)). The hemorrhage:muscle, lipid:muscle and intra-plaque lipid:hemorrhage signal intensity ratios (SIR) and contrast to noise ratios (CNR) were measured on MCW and compared to IDEAL black-blood images.No differences were found between any of the MCW methods for any of the SIRs measured. The IDEAL Fat images had higher lipid:muscle and lipid/hemorrhage SIRs (p<0.001) compared to IDEAL Water and all MCW image sequence types. The mean values of IDEAL Fat hemorrhage:muscle SIR and CNR were nearly unity (1.1±0.6) and nearly zero (0.1±1.1), respectively. The IDEAL Water imaging was not significantly different than any of the MCW methods for any of the SIRs or for the hemorrhage:muscle CNR of 3D-TOF, while its CNRs were significantly higher than IDEAL Fat lipid:muscle (p<0.05) and lipid:hemorrhage (p<0.001) and all MCW methods (p<0.001).The addition of IDEAL Water and Fat imaging to the MCW method shows potential to improve the identification of hemorrhage and lipid structures in carotid artery plaques.

Quantification of fat infiltration in the sacroiliac joints with ankylosing spondylitis using IDEAL sequence

To quantitatively assess fat infiltration in the sacroiliac joints (SIJs) of patients with ankylosing spondylitis (AS) by measuring the fat/water signal ratios of periarticular bone marrow with iterative decomposition of water and fat with echo asymmetry and least square estimation (IDEAL). Routine SIJ magnetic resonance imaging (MRI) and IDEAL were performed on 40 patients with AS and 30 healthy subjects. The fat infiltration regions (FIRs) and normal-appearing regions (NARs) of patients were measured based on the fat/water signal intensity on IDEAL. AS patients had higher fat/water signal ratios on FIRs and NARs (65.4-85.4%, p<0.05, and 44.1-70.7%, p<0.05, respectively) compared to healthy controls (38.3-43.3%). After treatment, the fat/water signal ratios of FIRs and NARs decreased (42.1-53.7% and 41.5-50.3%, respectively), but they remained higher than in the healthy controls (p<0.05). The fat infiltration was detected more effectively with a fat fraction map of the IDEAL sequence (95%) than other sequences, including the T1-weighted sequence (65%), and the fat/water signal ratios of the sacrum and ilium between the left and right sides of SIJs were approximately the same. The findings of this study suggest that IDEAL may be useful as a quantitative and objective method for evaluating the fat infiltration in the periarticular bone marrow of SIJs with AS; additionally, the sensitivity of IDEAL is better than that of routine sequences in detecting micro-fat infiltration of SIJs, and IDEAL can be used to quantitatively measure the adipose content and monitor patient follow-up after AS treatment.

Evaluation of the R2* value in invasive ductal carcinoma with respect to hypoxic-related prognostic factors using iterative decomposition of water and fat with echo asymmetry and least-squares emission (IDEAL)

To correlate the R2* value obtained by iterative decomposition of water and fat with echo asymmetry and least-squares emission (IDEAL) with fibrotic focus (FF), microvessel density and hypoxic biomarker (HIF-1α) in breast carcinoma. Forty-two patients who were diagnosed with invasive ductal carcinoma (IDC) of the breast underwent breast MRI including IDEAL before surgery. The entire region of interest (ROI) was delineated on the R2* map, and average tumour R2* value was calculated for each ROI. Histological specimens were evaluated for the presence of FF, the microvessel density (the average microvessel density and the ratio of peripheral to central microvessel density), and the grading of HIF-1α. FF was identified in 47.6% (20/42) of IDCs. Average R2* value for IDC with FF (42.4±13.2 Hz) was significantly higher than that without FF (28.5±13.9 Hz) (P = 0.01). Spearman rank correlation suggested that the average R2* value correlated with the grade of HIF-1α and the ratio of peripheral to central microvessel density for IDCs (P < 0.001). Quantification of tumour R2* using IDEAL is associated with the presence of FF and the overexpression of HIF-1α, and may therefore be useful in predicting hypoxia of breast carcinoma. • R2* value obtained by IDEAL correlates with the overexpression of HIF-1α. • R2* value obtained by IDEAL is associated with fibrotic focus. • R2* quantification may be useful in predicting hypoxia of breast carcinoma.

COMPARISON OF VARIOUS MRI FAT SUPPRESSION TECHNIQUES ON A WATER-FAT PHANTOM AT 1.5 T

Nowadays, magnetic resonance imaging (MRI) has been widely applied for diagnosis of soft-tissue diseases. Most clinical MRI protocols use fat suppression (FS) methods to suppress fat signal, reduce chemical shift artifacts, and increase conspicuity of lesions. To understand the advantages, disadvantages, and clinical applications of the most commonly used FS methods is an important issue. The aim of this study was to evaluate FS performance of six FS methods on a fat-water phantom at 1.5[Formula: see text]T. The six MRI methods included iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL), short inversion time inversion recovery (STIR), and four chemical presaturation (Chem Presat) methods. The phantom was composed of homogeneous oil-in-water emulsions with various fat contents ranging from 0 to 100% in increments of 10%. The difference between the suppressed fat fractions (FS fractions) and the true fat fractions of the phantom was used as an index of FS performance. The correlations and levels of agreement (LOAs) between the FS fractions determined using each FS method and the true fat fractions of the phantom were analyzed. From the phantom study, it was found that FSE T2 FS, STIR and IDEAL could achieve more accurate FS fractions than the other three methods. The FS fractions determined using FSE T2 FS, STIR and IDEAL were in a good agreement. On the contrary, T2-weighted spin echo Chem Presat had the most inaccurate quantification of FS fractions among these six FS methods. Both the ranks of signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the phantom were IDEAL [Formula: see text] FSE T2 FS [Formula: see text] STIR. The FS performance of these six FS methods in clinical use needs further study.

Sitagliptin in patients with non-alcoholic steatohepatitis: A randomized, placebo-controlled trial.

To evaluate the effect of sitagliptin vs placebo on histologic and non-histologic parameters of non-alcoholic steatohepatitis (NASH). Twelve patients with biopsy-proven NASH were randomized to sitagliptin (100 mg daily) (n = 6) or placebo (n = 6) for 24 wk. The primary outcome was improvement in liver fibrosis after 24 wk. Secondary outcomes included evaluation of changes in NAFLD activity score (NAS), individual components of NAS (hepatocyte ballooning, lobular inflammation, and steatosis), glycemic control and insulin resistance [including measurements of glycated hemoglobin (HbA1C) and adipocytokines], lipid profile including free fatty acids, adipose distribution measured using magnetic resonance imaging (MRI), and thrombosis markers (platelet aggregation and plasminogen activator inhibitor 1 levels). We also sought to determine the correlation between changes in hepatic fat fraction (%) [as measured using the Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation (IDEAL) MRI technique] and changes in hepatic steatosis on liver biopsy. Sitagliptin was not significantly better than placebo at reducing liver fibrosis score as measured on liver biopsy (mean difference between sitagliptin and placebo arms, 0.40, P = 0.82). There were no significant improvements evident with the use of sitagliptin vs placebo for the secondary histologic outcomes of NAS total score as well as for the individual components of NAS. Compared to baseline, those patients who received sitagliptin demonstrated improved HbA1C (6.7% ± 0.4% vs 7.9% ± 1.0%, P = 0.02), and trended towards improved adiponectin levels (4.7 ± 3.5 μg/mL vs 3.9 ± 2.7 μg/mL, P = 0.06) and triglyceride levels (1.26 ± 0.43 mmol/L vs 2.80 ± 1.64 mmol/L, P = 0.08). However, when compared with placebo, sitagliptin did not cause a statistically significant improvement in HbA1C (mean difference, -0.7%, P = 0.19) nor triglyceride levels (mean difference -1.10 mmol/L, P = 0.19) but did trend towards improved adiponectin levels only (mean difference, 0.60 μg/mL, P = 0.095). No significant changes in anthropometrics, liver enzymes, other adipocytokines, lipid profile, thrombosis parameters, or adipose distribution were demonstrated. The MRI IDEAL procedure correlated well with steatosis scores obtained on liver biopsy in both groups at baseline and post-treatment, and the Spearman correlation coefficients ranged from r = 0.819 (baseline) to r = 0.878 (post-treatment), P = 0.002. Sitagliptin does not improve fibrosis score or NAS after 24 wk of therapy. The MRI IDEAL technique may be useful for non-invasive measurement of hepatic steatosis.

Relationships between fatty infiltration in the thigh and calf in women with knee osteoarthritis.

In individuals with knee osteoarthritis (OA), fatty infiltration into thigh muscle is associated with poor physical performance and strength. However, it is not known whether this also occurs in the calf and if this impacts physical function. We investigated the relationships between volumes of intramuscular fat (intraMF), intermuscular fat (IMF), subcutaneous fat (SCF), lean muscle and muscle adiposity, in the thighs compared to the calves of women with knee OA. MRI scans of the thigh and calf were acquired from 20 women over 55years with knee OA (3.0T Discovery MR750, GE Healthcare). Axial IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) fat-separated images were segmented to quantify intraMF, IMF, SCF and lean muscle volumes (SliceOmatic 5.0, Tomovision). Correlation and linear regression analyses were run. We found a positive relationship between thigh and calf intraMF (R 2=0.592; B=5.49; p=0.001), muscle adiposity (R 2=0.539; B=0.567; p=0.001), and SCF volume (R 2=0.699; B=12.847; p=0.001), controlling for waist-to-hip ratio. Relationships between thigh and calf IMF (R 2=0.239; B=7.743; p=0.061), lean muscle (R 2=0.245; B=4.149; p=0.047) and combined intraMF and IMF volume (R 2=0.242; B=6.162; p=0.044) were not significant. Although a correlation exists between thigh and calf muscle adiposity, intraMF and SCF, this does not hold true for IMF or lean muscle. A greater amount of intraMF infiltration occurs in the thigh compared to the calf of women with knee OA. The calf and thigh may both be involved in pathologic changes in muscle composition in knee OA.