OBJECTIVE. The objective of our study was to assess the value of diffusion-weighted imaging in differentiating among the various subgroups of renal masses.
The purpose of this study was to determine if extracellular volume fraction and T1 mapping can be used to diagnose chronic pancreatitis (CP).This HIPAA-compliant study analyzed 143 consecutive patients with and without CP who underwent MR imaging between May 2016 and February 2017. Patients were selected for the study according to inclusion and exclusion criteria that considered history and clinical and laboratory findings. Eligible patients (n = 119) were grouped as normal (n = 60) or with mild (n = 22), moderate (n = 27), or severe (n = 10) CP on the basis of MRCP findings using the Cambridge classification as the reference standard. T1 maps were acquired in unenhanced and late contrast-enhanced phases using a 3D dual flip-angle gradient-echo sequence. All patients were imaged on the same 3-T scanner using the same imaging parameters, contrast agent, and dosage.Mean extracellular volume fractions and T1 relaxation times were significantly different within the study groups (one-way ANOVA, p < 0.001). Using the AUC curve analysis, extracellular volume fraction of > 0.27 showed 92% sensitivity (54/59) and 77% specificity (46/60) for the diagnosis of CP (AUC = 0.90). A T1 relaxation time of > 950 ms revealed 64% sensitivity (38/59) and 88% specificity (53/60) (AUC = 0.80). Combining extracellular volume fraction and T1 mapping yielded sensitivity of 85% (50/59) and specificity of 92% (55/60) (AUC = 0.94).Extracellular volume fraction and T1 mapping may provide quantitative metrics for determining the presence and severity of acinar cell loss and aid in the diagnosis of CP.
Objective: To research the long-term effects of delivery modes on structure and function of female anterior pelvic organs. Methods: Sixty- four women who gave birth to their babies more than five years were divided into vaginal delivery group and selective cesarean section group,32 women in each group. Their medical histories were collected,the prevalence of stress urinary incontinence( SUI)was evaluated by gynecological examination,the images of morphology and structure of anterior pelvic organs at rest and in Valsalva state were obtained by transperineal pelvic floor sonography,SUI related parameters were measured. Results: The long- term incidence rates of SUI and bladder prolapse in vaginal delivery group were statistically significantly higher than those in selective cesarean section group( P 0. 05). Urethral rotation angle in vaginal delivery group was statistically significantly larger than that in selective cesarean section group( P 0. 05). There was no statistically significant difference in the distance between bladder neck and lower margin of symphysis pubis and the posterior urethra- vesical angle at rest,the distance between bladder neck and lower margin of symphysis pubis and the posterior urethra- vesical angle,bladder neck mobility and the thickness of detrusor between the two groups( P 0. 05). Conclusion: The long-term effects of different delivery modes on structure and function of female anterior pelvic organs are different,the increase of incidence rate of SUI among the women adopting vaginal delivery may be correlated with bladder prolapse and larger urethral rotation angle.
OBJECTIVE. The purpose of this study was to determine if extracellular volume fraction and T1 mapping can be used to diagnose chronic pancreatitis (CP). MATERIALS AND METHODS. This HIPAA-compliant ...
Abstract Purpose To provide a rapid, non-invasive fat quantification technique capable of producing separate lipid component maps. Methods The calf muscles in 5 healthy adolescents (age 12-16 years; BMI = 20 ± 3 Kg/m 2 ) were scanned by two different fat fraction (FF) quantification methods. A high-resolution, density-weighted concentric ring trajectory (DW-CRT) metabolite cycling (MC) magnetic resonance spectroscopic imaging (MRSI) technique was implemented to collect data with 0.25 mL resolution within 3 minutes and 16 seconds. For comparative purposes, the standard Dixon technique was performed. The two techniques were compared using structural similarity (SSIM) analysis. Additionally, the difference in the distribution of each lipid over the adolescent calf muscles was assessed based on the MRSI data. Results The proposed MRSI technique provided individual FF maps for eight musculoskeletal lipids identified by LCModel analysis (L09, L11, L13, L15, L21, L23, L53, and L55) with mean SSIM indices of 0.19, 0.04, 0.03, 0.50, 0.45, 0.04, 0.07, and 0.12, respectively compared to that of Dixon’s FF map. Further analysis of voxels with zero SSIM demonstrated an increased sensitivity of FF lipid maps from data acquired using this MRSI technique over the standard Dixon technique. The trend of lipid spatial distribution over calf muscles was consistent with previously published findings in adults. Conclusion The advantages of this MRSI technique make it a useful tool when individual lipid FF maps are desired within a short scanning time.
Predicting Alzheimer's disease (AD) clinical scores offers a useful tool to monitor dementia progression at different time points. Previous machine learning methods usually focused on regressing the clinical scores directly but ignored the ambigu-ous information among score labels. In this study, we introduce a novel AD clinical scores prediction framework based on label distribution learning (LDL), named CSP-LDL. Notably, we first turn the clinical scores into a normal probability distribution of discrete labels to exploit uncertainty among the dementia scores. Then we learn the distribution of discrete labels by optimizing Kullback-Leibler (KL) divergence between the estimated and ground-truth distributions using a 3D CNN. Moreover, we further employ an expectation regression layer to regress clinical score value at the fine-grained level based on the predicted label distribution. Experiments on ADNI-1 and ADNI-2 datasets show that our CSP-LDL model outperforms existing state-of-the-art methods in terms of dementia regression accuracy at multiple time points using baseline structural magnetic resonance imaging (sMRI) data, demonstrating its effectiveness in early clinical diagnosis of AD.
Abstract: Robust and accurate fat suppression is highly desirable in breast magnetic resonance imaging (MRI) because it can considerably improve the image quality and lesion conspicuity. However, fat suppression is also more challenging in the breast compared with other regions in the body. Technical advances have been made over time to make fat suppression more efficient and reliable. Combined with other innovations, breast MRI continues to be the most sensitive and comprehensive diagnostic modality in the detection and evaluation of breast lesions. This review offers a critical comparison of various fat suppression techniques in breast MRI including spectral-selective excitation and saturation techniques based on the chemical shift difference between fat and water, the inversion recovery techniques based on the T1 relaxation time difference, the hybrid spectral-selective inversion recovery techniques, and the new Dixon fat and water separation techniques based on the phase difference between fat and water signal at different echo times. This review will also cover less frequently used techniques such as slice-selective gradient reversal. For each fat suppression technique in breast MRI, a detailed explanation of the technical principle, the advantages and disadvantages, the approaches for optimization as well as the clinical examples are included. The additional challenges of fat suppression in breast MRI at higher field strength and in the presence of metallic and silicone implants are also discussed. Keywords: breast MRI, fat suppression, dynamic contrast enhanced imaging, diffusion weighted imaging, magnetic resonance spectroscopy
The objective of our study was to determine the usefulness of the apparent diffusion coefficient (ADC) of liver parenchyma for determining the severity of liver fibrosis.This study investigated 78 patients who underwent diffusion-weighted imaging (DWI) with 1.5-T MRI and pathologic staging of liver fibrosis based on biopsy. DWI was performed with b values of 50 and 400 s/mm(2). ADCs of liver were measured using 2.0- to 3.0-cm(2) regions of interest in the right and left lobes of the liver; the mean ADC value was used for analysis. Pathologic METAVIR scores for liver fibrosis stage were used as a reference standard.The mean ADC values for fibrosis pathologically staged using the METAVIR classification system as F0 (n = 11), F1 (n = 16), F2 (n = 10), F3 (n = 14), and F4 (n = 27) were 125.9, 105.0, 104.5, 103.2, and 99.1 x 10(-5) s/mm(2), respectively. The correlation between the ADC values and the degree of liver fibrosis was moderate (Spearman's test, rho = -0.36). There was a significant difference in ADC values between patients with nonfibrotic liver (F0) and those with cirrhotic liver (F4) (p = 0.008). The best cutoff ADC value to distinguish between these groups was 118 x 10(-5) s/mm(2). However, ADC values were not useful for differentiating viral hepatitis patients with F2 fibrosis or higher from those with a lower degree of fibrosis (area under the receiver operating characteristic curve [AUC] = 0.66) or for differentiating low-stage fibrosis in all patients from high-stage fibrosis in all patients (AUC = 0.54).The ADCs in cirrhotic livers are significantly lower than those in nonfibrotic livers. However, ADC values measured using the current generation of scanners are not reliable enough to replace liver biopsy for staging hepatic fibrosis.
