Simultaneous use of Individual and Joint Regularization Terms in Compressive Sensing: Joint Reconstruction of Multi-Channel Multi-Contrast MRI Acquisitions

Purpose: A time-efficient strategy to acquire high-quality multi-contrast images is to reconstruct undersampled data with joint regularization terms that leverage common information across contrasts. However, these terms can cause leakage of uncommon features among contrasts, compromising diagnostic utility. The goal of this study is to develop a compressive sensing method for multi-channel multi-contrast magnetic resonance imaging (MRI) that optimally utilizes shared information while preventing feature leakage. Theory: Joint regularization terms group sparsity and colour total variation are used to exploit common features across images while individual sparsity and total variation are also used to prevent leakage of distinct features across contrasts. The multi-channel multi-contrast reconstruction problem is solved via a fast algorithm based on Alternating Direction Method of Multipliers. Methods: The proposed method is compared against using only individual and only joint regularization terms in reconstruction. Comparisons were performed on single-channel simulated and multi-channel in-vivo datasets in terms of reconstruction quality and neuroradiologist reader scores. Results: The proposed method demonstrates rapid convergence and improved image quality for both simulated and in-vivo datasets. Furthermore, while reconstructions that solely use joint regularization terms are prone to leakage-of-features, the proposed method reliably avoids leakage via simultaneous use of joint and individual terms. Conclusion: The proposed compressive sensing method performs fast reconstruction of multi-channel multi-contrast MRI data with improved image quality. It offers reliability against feature leakage in joint reconstructions, thereby holding great promise for clinical use.Comment: 13 pages, 13 figures. Submitted for possible publicatio

Genetics of Uveal Melanoma and Cutaneous Melanoma: Two of a Kind?

Cutaneous melanoma and uveal melanoma both derive from melanocytes but show remarkable differences in tumorigenesis, mode of metastatic spread, genetic alterations, and therapeutic response. In this review we discuss the differences and similarities along with the genetic research techniques available and the contribution to our current understanding of melanoma. The several chromosomal aberrations already identified prove to be very strong predictors of decreased survival in CM and UM patients. Especially in UM, where the overall risk of metastasis is high (45%), genetic research might aid clinicians in selecting high-risk patients for future systemic adjuvant therapies

Increased systemic oxidative stress in patients with keratoconus

PurposeTo establish the effect of systemic oxidative stress on the pathogenesis of keratoconus by measuring serum total oxidant status (TOS) and total antioxidant status (TAS) in patients with keratoconus.MethodsTwenty-five patients with keratoconus (keratoconus group) and 25 age-sex-matched healthy subjects (control group) were enrolled in the study. Exclusion criteria were smoking habit, history of any other corneal pathology, systemic disease or inflammation, and current antioxidant or anti-inflammatory therapies. All participants underwent a detailed ophthalmological examination and corneal topography. Serum samples were obtained from all participants. Oxidative stress markers (TAS and TOS) were measured using a commercial kit and oxidative stress index (OSI) was calculated.ResultsThe study comprised 25 patients with keratoconus (mean age of 26.4±1.7 years) and 25 healthy control subjects (mean age of 26.6±1.7 years) (P>0.05). The serum TOS and OSI values were significantly higher in patients with keratoconus compared with those of the controls (P=0.036 and 0.037, respectively). However, serum TAS did not show significant difference between the keratoconus and control groups (P=0.497).ConclusionsThe higher levels of serum oxidant status and OSI in patients with keratoconus suggest that systemic oxidative stress might be involved in the pathogenesis of keratoconus. © 2014 Macmillan Publishers Limited

Clinicopathologic characteristics and prognosis comparison of the uterine high grade endometrial carcinomas

Objectives: Grade 3 endometrioid adenocarcinomas (G3 EAC), type two endometrial carcinomas (Type 2 EC), and alsouterine carcinosarcomas (UCS) are considered as high-grade endometrial adenocarcinomas. The aim of this study was tocompare the clinicopathologic features and survival of patients with UCS, G3 EAC, Type2 EC.Material and methods: We included two hundred and thirty-five patients in this study. Patients were divided into threegroups according to the type of tumor as uterine G3 EAC (group 1, n = 62), Type 2 EC (serous, clear and mixed types; group 2,n = 93), and UCS (group 3, n = 80). We compared the groups according to age, initial symptom, surgical approach, stage,myometrial invasion (MI), lymph node invasion (LNI), lymphovascular space invasion (LVSI), adjuvant therapy, and survival.When comparing the survival outcomes the Kaplan-Meier analysis was performed.Results: The groups were similar according to age, menopausal status, nulliparity, initial symptoms, stage, LVSI, and LNI.Positive cytology was determined significantly more in group 3. There was a significant difference between the groups interms of myometrial invasion degree. Optimal cytoreduction was similar among the groups. The primary adjuvant treatmentwas chemotherapy for UCS and Type2 EAC whereas radiotherapy was the main adjuvant treatment for G3 EAC. Therewere no significant differences among the groups according to overall survival (OS) (p = 0.290).Conclusions: Although the survival difference among the groups can not be revealed, these patients have different clinicaland pathological features and they should be considered as different groups

Evaluation of Neutrophil to Lymphocyte and Platelet to Lymphocyte Ratios in Rheumatoid Arthritis

Objective: The purpose of this study is to investigate the relationship of disease activity with Neutrophil-Lympho­cyte Ratio (NLR) and Platelet Lymphocyte Ratio (PLR) and red blood cell distribution width (RDW). Methods: Seventy seven RA patients and 97 healthy sub­jects were examined retrospectively. People with chronic and systemic diseases were excluded from control group of the study. The disease activity scores (DAS 28) of pa­tient group, hematologic parameters and inflammation parameters of both groups were analyzed statistically us­ing independent t-test and spearman correlation test. Results: Age and gender was not found different be­tween groups. CRP and ESR levels were significantly higher in RA group (p<0.001). Hemoglobin and platelet count were lower (p<0.001 and p=0.022), while RDW, NLR, PLR and MPV levels were significantly higher in RA group (p<0.001, p<0.001. p<0.001, p<0.001, respec­tively). In patient group, ESR (p<0.001), lymphocytes (%) (p= 0.042), absolute neutrophil (p=0.047), and platelets (p= 0.019) were positively, whereas lymphocytes were negatively affected by improvement disease activity (DAS 28) scores. PLR levels significantly negatively correlated with MPV levels (r= -0.386) but showed a significant posi­tive correlation with RDW (r= 0.354) and NLR levels (r= 0.618). Conclusion: NLR and PLR are important and promising factors for disease activity estimation of rheumatoid ar­thritis and may be used in clinical practice. In our opinion, larger studies consisting larger group will help determina­tion of disease activity of RA by more specific indices us­ing these parameters

Joint reconstruction of multi-contrast images: compressive sensing reconstruction using both joint and individual regularization functions

In many clinical settings, multi-contrast images of a patient are acquired to maximize complementary information. With the underlying anatomy being the same, the mutual information in multi-contrast data can be exploited to improve image reconstruction, especially in accelerated acquisition schemes such as Compressive Sensing (CS). This study proposes a CS-reconstruction algorithm that uses four regularization functions; joint L1-sparsity and TV-regularization terms to exploit the mutual information, and individual L1-sparsity and TV-regularization terms to recover unique features in each image. The proposed method is shown to be robust against leakage-of-features across contrasts, and is demonstrated using simulations and in-vivo experiments

Secondary prevention of coronary heart disease in elderly population of Turkey: A subgroup analysis of ELDERTURK study

Background: Secondary prevention plays an important role after acute coronary event due to high risk of adverse events in elderly. In present study we aimed to evaluate the lifestyle, management of risk factors and medical treatment for secondary protection in elderly patients with known coronary heart disease (CHD). Methods: ELDERTURK is a non-interventional, multi-centered, observational study, which included total of 5694 elderly patients ( &gt; 65 years) from 50 centers in Turkey. In this study elderly patients from the ELDERTURK population with known CHD were evaluated for cardiovascular risk factors, comor- bidities and medication usage. Results: A total of 2976 (52.3% of study) out of 5694 patients included in the ELDERTURK study were evaluated. All had known CHD with a mean age of 73.4 ± 6.2 years and 60.3% were male. 13.0% of patients were smokers, 42.4% were overweight and 21.1% were obese. Only 23.6% of patients reported to do regular exercise, 73.4% had history of hypertension, 47.4% had dyslipidemia and 33.9% had diabetes mellitus. The rate of patients with systolic blood pressure &gt; 140 mmHg were 31.1% and only 13.9% of patients had a recommended ≤ 70 mg/dL level of low-density lipoprotein cholesterol. Anti- platelet, statin, beta-blocker and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker usage was limited to 27.3%. Conclusions: The ELDERTURK study shows that many patients with CHD have a high prevalence of modifiable risk factors and unhealthy lifestyle. Apart from this, many patients are not receiving thera- peutic intervention and as a consequence most were not achieving the recommended goals.   

Statistically segregated k-space sampling for accelerating multiple-acquisition MRI

A central limitation of multiple-acquisition magnetic resonance imaging (MRI) is the degradation in scan efficiency as the number of distinct datasets grows. Sparse recovery techniques can alleviate this limitation via randomly undersampled acquisitions. A frequent sampling strategy is to prescribe for each acquisition a different random pattern drawn from a common sampling density. However, naive random patterns often contain gaps or clusters across the acquisition dimension that in turn can degrade reconstruction quality or reduce scan efficiency. To address this problem, a statistically-segregated sampling method is proposed for multiple-acquisition MRI. This method generates multiple patterns sequentially, while adaptively modifying the sampling density to minimize k-space overlap across patterns. As a result, it improves incoherence across acquisitions while still maintaining similar sampling density across the radial dimension of k-space. Comprehensive simulations and in vivo results are presented for phase-cycled balanced steady-state free precession and multi-echo T2-weighted imaging. Segregated sampling achieves significantly improved quality in both Fourier and compressedsensing reconstructions of multiple-acquisition datasets