Exploiting parameter sparsity in model-based reconstruction to accelerate proton density and T2 mapping

Abstract Water, collagen, and proteoglycans determine articular cartilage functionality. If altered, susceptibility to premature degeneration is increased. This study investigated the effects of enzymatic proteoglycan depletion on cartilage functionality as assessed by advanced Magnetic Resonance Imaging (MRI) techniques under standardized loading. Lateral femoral condylar cartilage-bone samples from patients undergoing knee replacement (n = 29) were serially imaged by Proton Density-weighted and T1, T1ρ, T2, and T2* mapping sequences on a clinical 3.0 T MRI scanner (Achieva, Philips). Using pressure-controlled indentation loading, samples were imaged unloaded and quasi-statically loaded to 15.1 N and 28.6 N, and both before and after exposure to low-concentrated (LT, 0.1 mg/mL, n = 10) or high-concentrated trypsin (HT, 1.0 mg/mL, n = 10). Controls were not treated (n = 9). Responses to loading were assessed for the entire sample and regionally, i.e. sub- and peri-pistonally, and zonally, i.e. upper and lower sample halves. Trypsin effects were quantified as relative changes (Δ), analysed using appropriate statistical tests, and referenced histologically. Histological proteoglycan depletion was reflected by significant sub-pistonal decreases in T1 (p = 0.003) and T2 (p = 0.008) after HT exposure. Loading-induced changes in T1ρ and T2* were not related. In conclusion, proteoglycan depletion alters cartilage functionality and may be assessed using serial T1 and T2 mapping under loading.

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Acceleration of chemical shift encoding-based water fat MRI for liver proton density fat fraction and T2* mapping using compressed sensing

10.1101/19000927 ◽

2019 ◽

Author(s):

Fabian K. Lohöfer ◽

Georgios A. Kaissis ◽

Christina Müller-Leisse ◽

Daniela Franz ◽

Christoph Katemann ◽

...

Keyword(s):

Chemical Shift ◽

Compressed Sensing ◽

T2 Mapping ◽

Motion Artifacts ◽

Acceleration Factor ◽

Proton Density ◽

List Type ◽

Proton Density Fat Fraction ◽

Fat Fraction ◽

Total Acceleration

AbstractObjectivesTo evaluate proton density fat fraction (PDFF) and T2* measurements of the liver with combined parallel imaging (sensitivity encoding, SENSE) and compressed sensing (CS) accelerated chemical shift encoding-based water-fat separation.MethodsSix-echo Dixon imaging was performed in the liver of 89 subjects. The first acquisition variant used acceleration based on SENSE with a total acceleration factor equal to 2.64 (acquisition labeled as SENSE). The second acquisition variant used acceleration based on a combination of CS with SENSE with a total acceleration factor equal to 4 (acquisition labeled as CS+SENSE). Acquisition times were compared between acquisitions and proton density fat fraction (PDFF) and T2*-values were measured and compared separately for each liver segment.ResultsTotal scan duration was 14.5 sec for the SENSE accelerated image acquisition and 9.3 sec for the CS+SENSE accelerated image acquisition. PDFF and T2* values did not differ significantly between the two acquisitions (paired Mann-Whitney and paired t-test P>0.05 in all cases). CS+SENSE accelerated acquisition showed reduced motion artifacts (1.1%) compared to SENSE acquisition (12.3%).ConclusionCS+SENSE accelerates liver PDFF and T2*mapping while retaining the same quantitative values as an acquisition using only SENSE and reduces motion artifacts.Strengths of this studyCompressed sensing allows accelerated imaging with reduction of motion artifacts without alteration of quantitative measurementsRobust results in fat and iron quantification in a heterogeneous patient cohortLimitations of this studyNo histopathological validation of the MR findings was performedThe study was not performed at different field strengths

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Fast T2 mapping with multiple echo, caesar cipher acquisition and model-based reconstruction

Magnetic Resonance in Medicine ◽

10.1002/mrm.25221 ◽

2014 ◽

Vol 73 (3) ◽

pp. 1065-1074 ◽

Cited By ~ 12

Author(s):

Christopher L. Lankford ◽

Richard D. Dortch ◽

Mark D. Does

Keyword(s):

T2 Mapping ◽

Model Based

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Accelerated T2 mapping combining parallel MRI and model-based reconstruction: GRAPPATINI

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.25972 ◽

2018 ◽

Vol 48 (2) ◽

pp. 359-368 ◽

Cited By ~ 26

Author(s):

Tom Hilbert ◽

Tilman J. Sumpf ◽

Elisabeth Weiland ◽

Jens Frahm ◽

Jean-Philippe Thiran ◽

...

Keyword(s):

T2 Mapping ◽

Parallel Mri ◽

Model Based

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Bloch modelling enables robust T2 mapping using retrospective Proton Density and T2- weighted images from different vendors and sites

NeuroImage ◽

10.1016/j.neuroimage.2021.118116 ◽

2021 ◽

pp. 118116

Author(s):

Gitanjali Chhetri ◽

Kelly C. McPhee ◽

Alan H. Wilman

Keyword(s):

T2 Mapping ◽

Proton Density ◽

T2 Weighted Images

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Fast T2 Mapping With Improved Accuracy Using Undersampled Spin-Echo MRI and Model-Based Reconstructions With a Generating Function

IEEE Transactions on Medical Imaging ◽

10.1109/tmi.2014.2333370 ◽

2014 ◽

Vol 33 (12) ◽

pp. 2213-2222 ◽

Cited By ~ 32

Author(s):

Tilman J. Sumpf ◽

Andreas Petrovic ◽

Martin Uecker ◽

Florian Knoll ◽

Jens Frahm

Keyword(s):

Generating Function ◽

Spin Echo ◽

T2 Mapping ◽

Model Based ◽

Improved Accuracy

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T2* relaxometry maps of the uterus – Future prospectives with oncology implications

Journal of Clinical Images and Medical Case Reports ◽

10.52768/2766-7820/1102 ◽

2021 ◽

Vol 2 (3) ◽

Author(s):

Roxana M Pintican ◽

◽

Reka David Kerekes ◽

Vlad Bura ◽

Florin Stamatian ◽

...

Keyword(s):

Cervical Cancer ◽

Endometrial Cancer ◽

T2 Mapping ◽

Large Field ◽

Proton Density ◽

Pelvic Mri ◽

T2 Relaxometry ◽

Figo Staging ◽

Density Values ◽

Parametric Maps

T2* relaxometry mapping has found diverse applications in neuroradiology but was insufficiently evaluated in pelvis MRI. Further, staging of the uterine-related cancers may be sometimes a cumbersome. Our aim is to present the T2* relaxometry maps respectively relaxometry and proton density values in patients with endometrial and cervical cancer, together with their postoperative outcomes. Three patients with uterine-related cancers underwent a 3T pelvic MRI examination. The protocol included a large field-of-view (FOV = 28 cm), a short (TE=30 ms) and a long (TE = 200 ms) echo time sequences. T2* maps were obtained by the means of post-processing methods. Parametric maps showed same Relaxation Time (RT) between endometrial cancer and adjacent metastatic lymphadenopathy, respectively different RT between endometrial and cervical cancer. In conclusion, we presented the T2* relaxometry values of endometrial and cervical cancer, and discuss their possible implications in FIGO staging and patient management. Keywords: T2 relaxometry; T2 mapping; MRI; Endometrial cancer; Cervical cancer; FIGO staging.

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In–Situ Cartilage Functionality Assessment Based on Advanced MRI Techniques and Precise Compartmental Knee Joint Loading through Varus and Valgus Stress

Diagnostics ◽

10.3390/diagnostics11081476 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1476

Author(s):

Oliver Said ◽

Justus Schock ◽

Daniel Benjamin Abrar ◽

Philipp Schad ◽

Christiane Kuhl ◽

...

Keyword(s):

Knee Joint ◽

Repeated Measures ◽

T2 Mapping ◽

Relaxation Times ◽

Knee Joints ◽

Proton Density ◽

Friedman Test ◽

Valgus Stress ◽

Human Knee ◽

Human Knee Joint

Stress MRI brings together mechanical loading and MRI in the functional assessment of cartilage and meniscus, yet lacks basic scientific validation. This study assessed the response-to-loading patterns of cartilage and meniscus incurred by standardized compartmental varus and valgus loading of the human knee joint. Eight human cadaveric knee joints underwent imaging by morphologic (i.e., proton density-weighted fat-saturated and 3D water-selective) and quantitative (i.e., T1ρ and T2 mapping) sequences, both unloaded and loaded to 73.5 N, 147.1 N, and 220.6 N of compartmental pressurization. After manual segmentation of cartilage and meniscus, morphometric measures and T2 and T1ρ relaxation times were quantified. CT-based analysis of joint alignment and histologic and biomechanical tissue measures served as references. Under loading, we observed significant decreases in cartilage thickness (p < 0.001 (repeated measures ANOVA)) and T1ρ relaxation times (p = 0.001; medial meniscus, lateral tibia; (Friedman test)), significant increases in T2 relaxation times (p ≤ 0.004; medial femur, lateral tibia; (Friedman test)), and adaptive joint motion. In conclusion, varus and valgus stress MRI induces meaningful changes in cartilage and meniscus secondary to compartmental loading that may be assessed by cartilage morphometric measures as well as T2 and T1ρ mapping as imaging surrogates of tissue functionality.

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Imaging of articular cartilage: current concepts

Joints ◽

10.11138/jts/2014.2.3.137 ◽

2014 ◽

Vol 02 (03) ◽

pp. 137-140 ◽

Cited By ~ 20

Author(s):

Mario Ronga ◽

Gloria Angeretti ◽

Sergio Ferraro ◽

Giovanni De Falco ◽

Eugenio Genovese ◽

...

Keyword(s):

Water Distribution ◽

Articular Surface ◽

Spin Echo ◽

T2 Mapping ◽

Cartilage Tissue ◽

Fast Spin Echo ◽

Proton Density ◽

Gold Standard Method ◽

Repair Tissue ◽

Minimum Requirements

Magnetic resonance imaging (MRI) is the gold standard method for non-invasive assessment of joint cartilage, providing information on the structure, morphology and molecular composition of this tissue. There are certain minimum requirements for a MRI study of cartilage tissue: machines with a high magnetic field (> 1.5 Tesla); the use of surface coils; and the use of T2-weighted, proton density-weighted fast-spin echo (T2 FSE-DP) and 3D fat-suppressed T1-weighted gradient echo (3D-FS T1W GRE) sequences. For better contrast between the different joint structures, MR arthography is a method that can highlight minimal fibrillation or fractures of the articular surface and allow evaluation of the integrity of the native cartilagerepair tissue interface. To assess the biochemical composition of cartilage and cartilage repair tissue, various techniques have been proposed for studying proteoglycans [dGEMRIC, T1rho mapping, sodium (23Na) imaging MRI, etc.], collagen, and water distribution [T2 mapping, “magnetisation transfer contrast”, diffusion-weighted imaging (DWI), and so on]. Several MRI classifications have been proposed for evaluating the processes of joint degeneration (WORMS, BLOKS, ICRS) and post-surgical maturation of repair tissue (MOCART, 3D MOCART). In the future, isotropic 3D sequences set to improve image quality and facilitate the diagnosis of disorders of articular structures adjacent to cartilage.

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