Search results for: Mary A. McLean

Items from 1 to 20 out of 28 results

article

Enhancing the spatial resolution of hyperpolarized carbon‐13 MRI of human brain metabolism using structure guidance

Matthias J. Ehrhardt, Ferdia A. Gallagher, Mary A. McLean, Carola‐Bibiane Schönlieb

Magnetic Resonance in Medicine > 87 > 3 > 1301 - 1312

Purpose Dynamic nuclear polarization is an emerging imaging method that allows noninvasive investigation of tissue metabolism. However, the relatively low metabolic spatial resolution that can be achieved limits some applications, and improving this resolution could have important implications for the technique. Methods We propose to enhance the 3D resolution of carbon‐13 magnetic resonance imaging...

article

Combined ²³Na and ¹³C imaging at 3.0 Tesla using a single‐tuned large FOV birdcage coil

Joshua D. Kaggie, Titus Lanz, Mary A. McLean, Frank Riemer, more

Magnetic Resonance in Medicine > 86 > 3 > 1734 - 1745

Purpose An unmet need in carbon‐13 (¹³C)‐MRI is a transmit system that provides uniform excitation across a large FOV and can accommodate patients of wide‐ranging body habitus. Due to the small difference between the resonant frequencies, sodium‐23 (²³Na) coil developments can inform ¹³C coil design while being simpler to assess due to the higher naturally abundant ²³Na signal. Here we present a...

article

Characterization and correction of center‐frequency effects in X‐nuclear eddy current compensations on a clinical MR system

Mary A. McLean, R. Scott Hinks, Joshua D. Kaggie, Ramona Woitek, more

Magnetic Resonance in Medicine > 85 > 5 > 2370 - 2376

Purpose The aim of the study was to investigate whether incorrectly compensated eddy currents are the source of persistent X‐nuclear spectroscopy and imaging artifacts, as well as methods to correct this. Methods Pulse‐acquire spectra were collected for ¹H and X‐nuclei (²³Na or ³¹P) using the minimum TR permitted on a 3T clinical MRI system. Data were collected in 3 orientations (axial, sagittal,...

article

Creating a clinical platform for carbon‐13 studies using the sodium‐23 and proton resonances

James T. Grist, Esben S.S. Hansen, Juan D. Sánchez‐Heredia, Mary A. McLean, more

Magnetic Resonance in Medicine > 84 > 4 > 1817 - 1827

Purpose Calibration of hyperpolarized ¹³C‐MRI is limited by the low signal from endogenous carbon‐containing molecules and consequently requires ¹³C‐enriched external phantoms. This study investigated the feasibility of using either ²³Na‐MRI or ¹H‐MRI to calibrate the ¹³C excitation. Methods Commercial ¹³C‐coils were used to estimate the transmit gain and center frequency for ¹³C and ²³Na resonances...

article

Molecular imaging of the prostate: Comparing total sodium concentration quantification in prostate cancer and normal tissue using dedicated ¹³C and ²³Na endorectal coils

Tristan Barrett, Frank Riemer, Mary A. McLean, Joshua D. Kaggie, more

Journal of Magnetic Resonance Imaging > 51 > 1 > 90 - 97

Background There has been recent interest in nonproton MRI including hyperpolarized carbon‐13 (¹³C) imaging. Prostate cancer has been shown to have a higher tissue sodium concentration (TSC) than normal tissue. Sodium (²³Na) and ¹³C nuclei have a frequency difference of only 1.66 MHz at 3T, potentially enabling ²³Na imaging with a ¹³C‐tuned coil and maximizing the metabolic information obtained from...

article

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Frank Riemer, Damien McHugh, Fulvio Zaccagna, Daniel Lewis, more

Journal of Magnetic Resonance Imaging > 50 > 4 > 1278 - 1284

Background Sodium MRI (²³Na‐MRI)‐derived biomarkers such as total sodium concentration (TSC) have the potential to provide information on tumor cellularity and the changes in tumor microstructure that occur following therapy. Purpose To evaluate the repeatability and reproducibility of TSC measurements in the brains of healthy volunteers, providing evidence for the technical validation of ²³Na‐MRI‐derived...

article

Multi-site repeatability and reproducibility of MR fingerprinting of the healthy brain at 1.5 and 3.0 T

Guido Buonincontri, Laura Biagi, Alessandra Retico, Paolo Cecchi, more

NeuroImage > 2019 > 195 > C > 362-372

Fully-quantitative MR imaging methods are useful for longitudinal characterization of disease and assessment of treatment efficacy. However, current quantitative MRI protocols have not been widely adopted in the clinic, mostly due to lengthy scan times. Magnetic Resonance Fingerprinting (MRF) is a new technique that can reconstruct multiple parametric maps from a single fast acquisition in the transient...

article

Non-invasive assessment of glioma microstructure using VERDICT MRI: correlation with histology

Fulvio Zaccagna, Frank Riemer, Andrew N. Priest, Mary A. McLean, more

European Radiology > 2019 > 29 > 10 > 5559-5566

Purpose This prospective study evaluated the use of vascular, extracellular and restricted diffusion for cytometry in tumours (VERDICT) MRI to investigate the tissue microstructure in glioma. VERDICT-derived parameters were correlated with both histological features and tumour subtype and were also used to explore the peritumoural region. Methods Fourteen consecutive treatment-naïve patients (43...

article

Multi-parametric and multi-regional histogram analysis of MRI: modality integration reveals imaging phenotypes of glioblastoma

Chao Li, Shuo Wang, Angela Serra, Turid Torheim, more

European Radiology > 2019 > 29 > 9 > 4718-4729

Objectives Integrating multiple imaging modalities is crucial for MRI data interpretation. The purpose of this study is to determine whether a previously proposed multi-view approach can effectively integrate the histogram features from multi-parametric MRI and whether the selected features can offer incremental prognostic values over clinical variables. Methods Eighty newly-diagnosed glioblastoma...

article

Quantitative and textural analysis of magnetization transfer and diffusion images in the early detection of brain metastases

Nicola L. Ainsworth, Mary A. McLean, Dominick J.O. McIntyre, Davina J. Honess, more

Magnetic Resonance in Medicine > 77 > 5 > 1987 - 1995

Purpose The sensitivity of the magnetization transfer ratio (MTR) and apparent diffusion coefficient (ADC) for early detection of brain metastases was investigated in mice and humans. Methods Mice underwent MRI twice weekly for up to 31 d following intracardiac injection of the brain‐homing breast cancer cell line MDA‐MB231‐BR. Patients with small cell lung cancer underwent quarterly MRI for 1...

article

Assessment of early treatment response to neoadjuvant chemotherapy in breast cancer using non-mono-exponential diffusion models: a feasibility study comparing the baseline and mid-treatment MRI examinations

Reem Bedair, Andrew N. Priest, Andrew J. Patterson, Mary A. McLean, more

European Radiology > 2017 > 27 > 7 > 2726-2736

Objectives To assess the feasibility of the mono-exponential, bi-exponential and stretched-exponential models in evaluating response of breast tumours to neoadjuvant chemotherapy (NACT) at 3 T. Methods Thirty-six female patients (median age 53, range 32–75 years) with invasive breast cancer undergoing NACT were enrolled for diffusion-weighted MRI (DW-MRI) prior to the start of treatment. For assessment...

article

Detecting gas‐induced vasomotor changes via blood oxygenation level‐dependent contrast in healthy breast parenchyma and breast carcinoma

Tess E. Wallace, Andrew J. Patterson, Oshaani Abeyakoon, Reem Bedair, more

Journal of Magnetic Resonance Imaging > 44 > 2 > 335 - 345

Purpose To evaluate blood oxygenation level‐dependent (BOLD) contrast changes in healthy breast parenchyma and breast carcinoma during administration of vasoactive gas stimuli. Materials and Methods Magnetic resonance imaging (MRI) was performed at 3T in 19 healthy premenopausal female volunteers using a single‐shot fast spin echo sequence to acquire dynamic T₂‐weighted images. 2% (n = 9) and 5%...

article

A comparison of quantitative methods for clinical imaging with hyperpolarized ¹³C‐pyruvate

Charlie J. Daniels, Mary A. McLean, Rolf F. Schulte, Fraser J. Robb, more

NMR in Biomedicine > 29 > 4 > 387 - 399

Dissolution dynamic nuclear polarization (DNP) enables the metabolism of hyperpolarized ¹³C‐labelled molecules, such as the conversion of [1‐¹³C]pyruvate to [1‐¹³C]lactate, to be dynamically and non‐invasively imaged in tissue. Imaging of this exchange reaction in animal models has been shown to detect early treatment response and correlate with tumour grade. The first human DNP study has recently...

article

Multi‐institutional validation of a novel textural analysis tool for preoperative stratification of suspected thyroid tumors on diffusion‐weighted MRI

Anna M. Brown, Sidhartha Nagala, Mary A. McLean, Yonggang Lu, more

Magnetic Resonance in Medicine > 75 > 4 > 1708 - 1716

Purpose Ultrasound‐guided fine needle aspirate cytology fails to diagnose many malignant thyroid nodules; consequently, patients may undergo diagnostic lobectomy. This study assessed whether textural analysis (TA) could noninvasively stratify thyroid nodules accurately using diffusion‐weighted MRI (DW‐MRI). Methods This multi‐institutional study examined 3T DW‐MRI images obtained with spin echo...

article

Multimodal MRI can identify perfusion and metabolic changes in the invasive margin of glioblastomas

Stephen J. Price, Adam M.H. Young, William J. Scotton, Jared Ching, more

Journal of Magnetic Resonance Imaging > 43 > 2 > 487 - 494

PurposeTo use perfusion and magnetic resonance (MR) spectroscopy to compare the diffusion tensor imaging (DTI)‐defined invasive and noninvasive regions. Invasion of normal brain is a cardinal feature of glioblastomas (GBM) and a major cause of treatment failure. DTI can identify invasive regions. Materials and MethodsIn all, 50 GBM patients were imaged preoperatively at 3T with anatomic sequences,...

article

Slice-selective broadband refocusing pulses for the robust generation of crushed spin-echoes

Martin A. Janich, Mary A. McLean, Ralph Noeske, Steffen J. Glaser, more

Journal of Magnetic Resonance > 2012 > 223 > Complete > 129-137

A major challenge for in vivo magnetic resonance spectroscopy with point-resolved spectroscopy (PRESS) is the low signal intensity for the measurement of weakly scalar coupled spins, for example lactate. The chemical-shift displacement error between the two coupling partners of the lactate molecule leads to a signal decrease. The chemical-shift displacement error is decreased and therefore the lactate...

article

Repeatability of edited lactate and other metabolites in astrocytoma at 3T

Mary A. McLean, Amy Sun, Thomas E. Bradstreet, Andrea K. Schaeffer, more

Journal of Magnetic Resonance Imaging > 36 > 2 > 468 - 475

Purpose:To assess the repeatability of measurement of lactate and other metabolites in tumors using magnetic resonance spectroscopy (MRS). Materials and Methods:MRS with spectral editing for lactate was performed on 10 patients with astrocytoma (two Grade III, eight Grade IV) using an 8‐channel receive coil at 3T. Lactate, lipid, choline, creatine, and N‐acetyl aspartate (NAA) signals were measured...

article

Reply to: Hippocampal Glutamate Levels and Striatal Dopamine D2/3 Receptor Occupancy in Subjects at Ultra High Risk of Psychosis

James M. Stone, Oliver D. Howes, Alice Egerton, Joseph Kambeitz, more

Biological Psychiatry > 2011 > 70 > 1 > e3-e4

article

Prostate cancer metabolite quantification relative to water in ¹H‐MRSI in vivo at 3 Tesla

Mary A. McLean, Tristan Barrett, Vincent J. Gnanapragasam, Andrew N. Priest, more

Magnetic Resonance in Medicine > 65 > 4 > 914 - 919

¹H magnetic resonance spectroscopic imaging was performed on 16 men with suspected prostate cancer using an 8‐channel external receive coil at 3 T. Choline and citrate (Cit) signals were measured in prostate lesions and normal‐appearing peripheral zone as identified on T₂‐weighted images. Metabolites were quantified relative to unsuppressed water from a separately acquired magnetic resonance spectroscopic...

article

Altered Relationship Between Hippocampal Glutamate Levels and Striatal Dopamine Function in Subjects at Ultra High Risk of Psychosis

James M. Stone, Oliver D. Howes, Alice Egerton, Joseph Kambeitz, more

Biological Psychiatry > 2010 > 68 > 7 > 599-602

Animal models of psychosis propose that striatal hyperdopaminergia is driven by abnormalities in hippocampal glutamatergic neurotransmission, but this has never been tested in humans.Sixteen individuals with an at-risk mental state for psychosis (ARMS) and 12 control subjects underwent proton magnetic resonance spectroscopy to estimate hippocampal glutamate and [18F]DOPA positron emission tomography...

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Search results for: Mary A. McLean

Enhancing the spatial resolution of hyperpolarized carbon‐13 MRI of human brain metabolism using structure guidance

Combined ²³Na and ¹³C imaging at 3.0 Tesla using a single‐tuned large FOV birdcage coil

Characterization and correction of center‐frequency effects in X‐nuclear eddy current compensations on a clinical MR system

Creating a clinical platform for carbon‐13 studies using the sodium‐23 and proton resonances

Molecular imaging of the prostate: Comparing total sodium concentration quantification in prostate cancer and normal tissue using dedicated ¹³C and ²³Na endorectal coils

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Multi-site repeatability and reproducibility of MR fingerprinting of the healthy brain at 1.5 and 3.0 T

Non-invasive assessment of glioma microstructure using VERDICT MRI: correlation with histology

Multi-parametric and multi-regional histogram analysis of MRI: modality integration reveals imaging phenotypes of glioblastoma

Quantitative and textural analysis of magnetization transfer and diffusion images in the early detection of brain metastases

Assessment of early treatment response to neoadjuvant chemotherapy in breast cancer using non-mono-exponential diffusion models: a feasibility study comparing the baseline and mid-treatment MRI examinations

Detecting gas‐induced vasomotor changes via blood oxygenation level‐dependent contrast in healthy breast parenchyma and breast carcinoma

A comparison of quantitative methods for clinical imaging with hyperpolarized ¹³C‐pyruvate

Multi‐institutional validation of a novel textural analysis tool for preoperative stratification of suspected thyroid tumors on diffusion‐weighted MRI

Multimodal MRI can identify perfusion and metabolic changes in the invasive margin of glioblastomas

Slice-selective broadband refocusing pulses for the robust generation of crushed spin-echoes

Repeatability of edited lactate and other metabolites in astrocytoma at 3T

Reply to: Hippocampal Glutamate Levels and Striatal Dopamine D2/3 Receptor Occupancy in Subjects at Ultra High Risk of Psychosis

Prostate cancer metabolite quantification relative to water in ¹H‐MRSI in vivo at 3 Tesla

Altered Relationship Between Hippocampal Glutamate Levels and Striatal Dopamine Function in Subjects at Ultra High Risk of Psychosis

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