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https://www.readbyqxmd.com/read/28630889/subspace-aware-recovery-of-low-rank-and-jointly-sparse-signals
#1
Sampurna Biswas, Soura Dasgupta, Raghuraman Mudumbai, Mathews Jacob
We consider the recovery of a matrix X, which is simultaneously low rank and joint sparse, from few measurements of its columns using a two-step algorithm. Each column of X is measured using a combination of two measurement matrices; one which is the same for every column, while the the second measurement matrix varies from column to column. The recovery proceeds by first estimating the row subspace vectors from the measurements corresponding to the common matrix. The estimated row subspace vectors are then used to recover X from all the measurements using a convex program of joint sparsity minimization...
March 2017: IEEE Transactions on Computational Imaging
https://www.readbyqxmd.com/read/28616730/contrast-enhanced-3t-mr-perfusion-of-musculoskeletal-tumours-t1-value-heterogeneity-assessment-and-evaluation-of-the-influence-of-t1-estimation-methods-on-quantitative-parameters
#2
Pedro Augusto Gondim Teixeira, Christophe Leplat, Bailiang Chen, Jacques De Verbizier, Marine Beaumont, Sammy Badr, Anne Cotten, Alain Blum
OBJECTIVE: To evaluate intra-tumour and striated muscle T1 value heterogeneity and the influence of different methods of T1 estimation on the variability of quantitative perfusion parameters. MATERIAL AND METHODS: Eighty-two patients with a histologically confirmed musculoskeletal tumour were prospectively included in this study and, with ethics committee approval, underwent contrast-enhanced MR perfusion and T1 mapping. T1 value variations in viable tumour areas and in normal-appearing striated muscle were assessed...
June 14, 2017: European Radiology
https://www.readbyqxmd.com/read/28616725/the-role-of-t1-perfusion-based-classification-in-magnetic-resonance-guided-high-intensity-focused-ultrasound-ablation-of-uterine-fibroids
#3
Bilgin Keserci, Nguyen Minh Duc
OBJECTIVE: To comparatively evaluate the role of magnetic resonance (MR) T1 perfusion-based time-signal intensity (SI) curves of fibroid tissue and the myometrium in classification of fibroids for predicting treatment outcomes of high-intensity focused ultrasound (HIFU) treatment. METHODS: The fibroids of 74 women who underwent MR-HIFU treatment were classified into group A (time-SI curve of fibroid lower than that of the myometrium) and group B (time-SI curve of fibroid equal to or higher than that of the myometrium)...
June 14, 2017: European Radiology
https://www.readbyqxmd.com/read/28608327/diffusional-kurtosis-imaging-dki-incorporation-into-an-intravoxel-incoherent-motion-ivim-mr-model-to-measure-cerebral-hypoperfusion-induced-by-hyperventilation-challenge-in-healthy-subjects
#4
Aude Pavilla, Giulio Gambarota, Alessandro Arrigo, Mehdi Mejdoubi, Régis Duvauferrier, Hervé Saint-Jalmes
OBJECTIVES: The objectives were to investigate the diffusional kurtosis imaging (DKI) incorporation into the intravoxel incoherent motion (IVIM) model for measurements of cerebral hypoperfusion in healthy subjects. MATERIALS AND METHODS: Eight healthy subjects underwent a hyperventilation challenge with a 4-min diffusion weighted imaging protocol, using 8 b values chosen with the Cramer-Rao Lower Bound optimization approach. Four regions of interest in gray matter (GM) were analyzed with the DKI-IVIM model and the bi-exponential IVIM model, for normoventilation and hyperventilation conditions...
June 12, 2017: Magma
https://www.readbyqxmd.com/read/28596576/knee-subchondral-bone-perfusion-and-its-relationship-to-marrow-fat-and-trabeculation-on-multi-parametric-mri-and-micro-ct-in-experimental-ckd
#5
Chao-Ying Wang, Yu-Juei Hsu, Yi-Jen Peng, Herng-Sheng Lee, Yue-Cune Chang, Chih-Shan Chang, Shih-Wei Chiang, Yi-Chih Hsu, Ming-Huang Lin, Guo-Shu Huang
The pathogenesis of chronic kidney disease (CKD) is multifactorial. In the progression of CKD arthropathy, arteriosclerosis may alter the knee subchondral bone marrow by altering blood flow through the bone vasculature. Herein, multi-parametric MRI assessment, including dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), magnetic resonance spectroscopy (MRS), MRI T2*, contrast enhanced MR angiography (CE-MRA), and micro-CT were applied in a rodent nephrectomy model to: 1) investigate the blood perfusion of subchondral bone marrow and its relationship to fat water content and trabeculation pattern in CKD and 2) demonstrate the feasibility of using multi-parametric MRI parameters as imaging biomarkers to evaluate the disease's progression...
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28596191/perfusion-mr-imaging-using-a-3d-pulsed-continuous-arterial-spin-labeling-method-for-acute-cerebral-infarction-classified-as-branch-atheromatous-disease-involving-the-lenticulostriate-artery-territory
#6
Y Shinohara, A Kato, K Kuya, K Okuda, M Sakamoto, H Kowa, T Ogawa
BACKGROUND AND PURPOSE: Branch atheromatous disease is a stroke subtype considered a risk factor for early neurologic deterioration. Meanwhile, crossed cerebellar diaschisis is thought to be influenced by the degree and location of supratentorial perfusion abnormalities and is associated with the clinical outcome in the case of an ischemic stroke. In this article, our aim was to clarify the utility of using a whole-brain 3D pulsed continuous arterial spin-labeling method as an imaging biomarker for predicting neurologic severity in branch atheromatous disease...
June 8, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28595499/thermal-diffusivity-and-perfusion-constants-from-in-vivo-mr-guided-focused-ultrasound-treatments-a-feasibility-study
#7
Christopher R Dillon, Viola Rieke, Pejman Ghanouni, Allison Payne
PURPOSE: This study investigates the feasibility of non-invasively determining thermal diffusivity (α) and the Pennes perfusion parameter (w) from preclinical and clinical magnetic resonance-guided focused ultrasound (MRgFUS) temperature data. MATERIALS AND METHODS: Pre-clinical MRgFUS experiments were performed in rabbit muscle (N = 3, 28 sonications) using three-dimensional MR thermometry. 8 sonications were made in a clinical QA phantom with two-dimensional thermometry...
June 8, 2017: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/28590938/combined-passive-acoustic-mapping-and-magnetic-resonance-thermometry-for-monitoring-phase-shift-nanoemulsion-enhanced-focused-ultrasound-therapy
#8
Calum Crake, F Can Meral, Mark Burgess, Iason Papademetriou, Nathan McDannold, Tyrone Porter
Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure...
June 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28583628/lymph-node-metastasis-in-head-and-neck-squamous-carcinoma-efficacy-of-intravoxel-incoherent-motion-magnetic-resonance-imaging-for-the-differential-diagnosis
#9
Long Liang, Xiaoning Luo, Zhouyang Lian, Wenbo Chen, Bin Zhang, Yuhao Dong, Changhong Liang, Shuixing Zhang
PURPOSE: To evaluate the value of pure molecular diffusion(D), perfusion-related diffusion (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) based on intravoxel incoherent motion (IVIM) theory for differential diagnosis of metastatic lymph nodes (LNs) in head and neck squamous cell carcinoma(HNSCC). MATERIALS AND METHODS: 29 patients with HNSCC and 20 patients with lymph node hyperplasia (LNH) were enrolled in this retrospective study, underwent magnetic resonance (MR) examination...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28579039/total-mismatch-of-diffusion-weighted-imaging-and-susceptibility-weighted-imaging-in-patients-with-acute-cerebral-ischemia
#10
Min-Gyu Park, Jeong A Yeom, Seung Kug Baik, Kyung-Pil Park
BACKGROUND AND PURPOSE: Multiple hypointense vessels (MHV) on susceptibility-weighted imaging (SWI) is associated with an increased oxygen demand in acute cerebral ischemia. Occasionally, some patients exhibit extensive MHV on SWI despite of negative diffusion-weighted imaging (DWI), which is a phenomenon called total mismatch DWI-SWI. We analyzed the clinical characteristics and imaging findings in patients with the total DWI-SWI mismatch. MATERIALS AND METHODS: We selected patients with total DWI-SWI mismatch who underwent MRI within 12hours from onset...
May 31, 2017: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28577544/deactivation-vs-asynchronous-pacing-prospective-evaluation-of-a-protocol-for-rhythm-management-in-patients-with-magnetic-resonance-conditional-pacemakers-undergoing-adenosine-stress-cardiovascular-magnetic-resonance-imaging
#11
Oliver Klein-Wiele, Marietta Garmer, Gianluca Barbone, Rhyan Urbien, Martin Busch, Kaffer Kara, Harald Schäfer, Michael Schulte-Hermes, Birgit Hailer, Dietrich Grönemeyer
BACKGROUND: Cardiovascular Magnetic Resonance (CMR) imaging with adenosine stress is an important diagnostic tool in patients with known or suspected coronary artery disease (CAD). However, the method is not yet established for CAD patients with pacemakers (PM) in clinical practice. A possible reason is that no recommendations exist for PM setting (paused pacing or asynchronous mode) during adenosine stress. We elaborated a protocol for rhythm management in clinical routine for PM patients that considers heart rate changes under adenosine using a test infusion of adenosine in selected patients...
June 2, 2017: BMC Cardiovascular Disorders
https://www.readbyqxmd.com/read/28574817/intravoxel-incoherent-motion-diffusion-weighted-mr-imaging-parameters-predict-pathological-classification-in-thymic-epithelial-tumors
#12
Gang-Feng Li, Shi-Jun Duan, Lin-Feng Yan, Wen Wang, Yong Jing, Wei-Qiang Yan, Qian Sun, Shu-Mei Wang, Hai-Yan Nan, Tian-Yong Xu, Dan-Dan Zheng, Yu-Chuan Hu, Guang-Bin Cui
We evaluated the performance of intravoxel incoherent motion (IVIM) parameters for preoperatively predicting the subtype and Masaoka stage of thymic epithelial tumors (TETs). Seventy-seven patients with pathologically confirmed TETs underwent a diffusion weighted imaging (DWI) sequence with 9 b values. Differences in the slow diffusion coefficient (D), fast perfusion coefficient (D*), and perfusion fraction (f) IVIM parameters, as well as the multi b-value fitted apparent diffusion coefficient (ADCmb), were compared among patients with low-risk (LRT) and high-risk thymomas (HRT) and thymic carcinomas (TC), and between early stage (stages I and II) and advanced stage (stages III and IV) TET patients...
May 15, 2017: Oncotarget
https://www.readbyqxmd.com/read/28572147/head-to-head-visual-comparison-between-brain-perfusion-spect-and-arterial-spin-labeling-mri-with-different-postlabeling-delays-in-alzheimer-disease
#13
T Kaneta, O Katsuse, T Hirano, W Ogawa, K Yoshida, T Odawara, Y Hirayasu, T Inoue
BACKGROUND AND PURPOSE: Arterial spin-labeling MR imaging has been recently developed as a noninvasive technique with magnetically labeled arterial blood water as an endogenous contrast medium for the evaluation of CBF. Our aim was to compare arterial spin-labeling MR imaging and SPECT in the visual assessment of CBF in patients with Alzheimer disease. MATERIALS AND METHODS: In 33 patients with Alzheimer disease or mild cognitive impairment due to Alzheimer disease, CBF images were obtained by using both arterial spin-labeling-MR imaging with a postlabeling delay of 1...
June 1, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28570033/quantitative-mri-and-spectroscopy-of-bone-marrow
#14
REVIEW
Dimitrios C Karampinos, Stefan Ruschke, Michael Dieckmeyer, Maximilian Diefenbach, Daniela Franz, Alexandra S Gersing, Roland Krug, Thomas Baum
Bone marrow is one of the largest organs in the human body, enclosing adipocytes, hematopoietic stem cells, which are responsible for blood cell production, and mesenchymal stem cells, which are responsible for the production of adipocytes and bone cells. Magnetic resonance imaging (MRI) is the ideal imaging modality to monitor bone marrow changes in healthy and pathological states, thanks to its inherent rich soft-tissue contrast. Quantitative bone marrow MRI and magnetic resonance spectroscopy (MRS) techniques have been also developed in order to quantify changes in bone marrow water-fat composition, cellularity and perfusion in different pathologies, and to assist in understanding the role of bone marrow in the pathophysiology of systemic diseases (e...
June 1, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28557798/thermal-ablation-of-a-confluent-lesion-in-the-porcine-kidney-with-a-clinically-available-mr-hifu-system
#15
J M M van Breugel, M de Greef, J W Wijlemans, G Schubert, M A A J van den Bosch, C T W Moonen, M G Ries
The incidence of small renal masses (SRMs) sized  <4 cm has increased over the decades (as co-findings/or due to introduction of cross sectional imaging). Currently, partial nephrectomy (PN) or watchful waiting is advised in these patients. Ultimately, 80-90% of these SRMs require surgical treatment and PN is associated with a 15% complication rate. In this aging population, with possible comorbidities and poor health condition, both PN and watchful waiting are non-ideal treatment options. This resulted in an increased need for early, non-invasive treatment strategies such as MR-guided high intensity focused ultrasound (MR-HIFU)...
July 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28550465/differential-diagnosis-of-oligodendroglial-and-astrocytic-tumors-using-imaging-results-the-added-value-of-perfusion-mr-imaging
#16
Hyun Jung Yoon, Kook Jin Ahn, Song Lee, Jin Hee Jang, Hyun Seok Choi, So Lyung Jung, Bum Soo Kim, Shin Soo Jeun, Yong Kil Hong
PURPOSE: The purposes of the present study are to assess whether different characteristics of oligodendrogliomas and astrocytic tumors are visible on MR imaging and to determine the added value of perfusion imaging in conventional MR imaging when differentiating oligodendrogliomas from astrocytic tumors. METHODS: We retrospectively studied 22 oligodendroglioma and 54 astrocytic tumor patients, including glioblastoma multiforme (GBM). The morphological tumor characteristics were evaluated using MR imaging...
May 26, 2017: Neuroradiology
https://www.readbyqxmd.com/read/28547590/perfusion-and-diffusion-mri-signatures-in-histologic-and-genetic-subtypes-of-who-grade-ii-iii-diffuse-gliomas
#17
Kevin Leu, Garrett A Ott, Albert Lai, Phioanh L Nghiemphu, Whitney B Pope, William H Yong, Linda M Liau, Timothy F Cloughesy, Benjamin M Ellingson
The value of perfusion and diffusion-weighted MRI in differentiating histological subtypes according to the 2007 WHO glioma classification scheme (i.e. astrocytoma vs. oligodendroglioma) and genetic subtypes according to the 2016 WHO reclassification (e.g. 1p/19q co-deletion and IDH1 mutation status) in WHO grade II and III diffuse gliomas remains controversial. In the current study, we describe unique perfusion and diffusion MR signatures between histological and genetic glioma subtypes. Sixty-five patients with 2007 histological designations (astrocytomas and oligodendrogliomas), 1p/19q status (+ = intact/- = co-deleted), and IDH1 mutation status (MUT/WT) were included in this study...
May 25, 2017: Journal of Neuro-oncology
https://www.readbyqxmd.com/read/28543071/differentiating-enhancing-multiple-sclerosis-lesions-glioblastoma-and-lymphoma-with-dynamic-texture-parameters-analysis-dtpa-a-feasibility-study
#18
Rajeev K Verma, Roland Wiest, C Locher, Mirjam R Heldner, Phillip Schucht, Andreas Raabe, Jan Gralla, Christian Philipp Kamm, Johannes Slotboom, Frauke Kellner-Weldon
PURPOSE: MR-imaging hallmarks of glioblastoma (GB), cerebral lymphoma (CL), and demyelinating lesions are gadolinium (Gd) uptake due to blood brain barrier disruption. Thus, initial diagnosis may be difficult based on conventional Gd enhanced MRI alone. Here, the added value of a dynamic texture parameter analysis (DTPA) in the differentiation between these three entities is examined. DTPA is an in-house software tool that incorporates the analysis of quantitative texture parameters extracted from dynamic susceptibility contrast enhanced (DSCE) images...
May 19, 2017: Medical Physics
https://www.readbyqxmd.com/read/28542553/quantitative-mri-for-analysis-of-peritumoral-edema-in-malignant-gliomas
#19
Ida Blystad, J B Marcel Warntjes, Örjan Smedby, Peter Lundberg, Elna-Marie Larsson, Anders Tisell
BACKGROUND AND PURPOSE: Damage to the blood-brain barrier with subsequent contrast enhancement is a hallmark of glioblastoma. Non-enhancing tumor invasion into the peritumoral edema is, however, not usually visible on conventional magnetic resonance imaging. New quantitative techniques using relaxometry offer additional information about tissue properties. The aim of this study was to evaluate longitudinal relaxation R1, transverse relaxation R2, and proton density in the peritumoral edema in a group of patients with malignant glioma before surgery to assess whether relaxometry can detect changes not visible on conventional images...
2017: PloS One
https://www.readbyqxmd.com/read/28540825/the-role-of-t1-perfusion-based-classification-in-predicting-the-outcome-of-magnetic-resonance-guided-high-intensity-focused-ultrasound-treatment-of-adenomyosis
#20
Bilgin Keserci, Nguyen Minh Duc
OBJECTIVE: To assess the relationship between magnetic resonance (MR) T1 perfusion-based classification and the outcome of MR-guided high intensity focused ultrasound treatment of adenomyosis, defined as nonperfused volume (NPV) ratio. METHODS: The adenomyosis of 31 women was classified into group A (time-signal intensity [SI] curve of adenomyosis lower than that of the myometrium) and group B (time-SI curve of adenomyosis equal to or higher than that of the myometrium) on the basis of time-SI curves on dynamic contrast enhanced (DCE) MR images acquired at screening...
May 19, 2017: International Journal of Hyperthermia
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