QA: Quality Assurance, Accuracy, Precision and Phantoms

Tofts, Paul S.

doi:10.1002/0470869526.ch3

Cited by 24 publications

(34 citation statements)

References 61 publications

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“… ( a ) Photograph of the current source. (b) Phantom 1 was spherical with a diameter of 10 cm, filled with saline (1.45 g/L of NaCl) and doped with 0.1 mM of MnCl 2 to reach relaxation times of T 1 = 1.1 s and T 2 = 100 ms . T 1 values were determined by repeating an inversion recovery gradient recalled echo (IR‐GRE) sequence for different inversion times.…”

Section: Methodsmentioning

confidence: 99%

Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

Göksu

Scheffler

Ehses

et al. 2017

Magnetic Resonance in Med

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Section: Methodsmentioning

confidence: 99%

Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

Göksu

Scheffler

Ehses

et al. 2017

Magnetic Resonance in Med

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“…Potential disadvantages include "a lack of realism compared to in vivo measurements", "MR properties of the material progressively vary with time" and "the time and expertise required to build phantoms are prohibitive at some centres" [127] . Some phantoms have been developed to measure some tissue properties that exist in tumours [130] . Phantom measurements have been made with alkanes [131] or other organic liquids [132] , which have ADC values in the range of brain tissue.…”

Section: Reproducibility Of Adc Values In Vitromentioning

confidence: 99%

Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients,in-vitroandin-vivoreproducibility

Jafar

Parsaï

Miquel

2016

WJR

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There is considerable disparity in the published apparent diffusion coefficient (ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation, which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript, a review of selected articles published to date in healthy extracranial body diffusion-weighted magnetic resonance imaging is presented, detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma, 15 for kidney (renal parenchyma), 14 for spleen, 13 for pancreatic body, 6 for gallbladder, 13 for prostate, 13 for uterus (endometrium, myometrium, cervix) In addition, six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript, it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population, as variations are far more significant in vivo compared with phantom studies. Core tip: Diffusion-weighted magnetic resonance imaging was highlighted as a potential cancer imaging biomarker by a team of experts in a report published in 2009. We review the variability of published diffusion values in the major extra-cranial organs and focus on the validation literature, both in vivo and in vitro . A total of 115 studies were selected including for liver parenchyma, kidney, pancreatic body, spleen, gallbladder, prostate, uterus (endometrium, myometrium, cervix) and breast. We also look in detail at the published repeatability and reproducibility studies, both in vivo and in phantoms. A series of recommendations based on our findings are given at the end of this review.Jafar MM, Parsai A, Miquel ME. Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients, in vitro and in vivo reproducibility.

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“…r 1 is the relaxivity; a value of 8 s -1 mM -1 was used (measured in vitro at 1.4T and 23 °C) [23] (and see reference[24] page 72).…”

Section: Modellingmentioning

confidence: 99%

Toward clinical application of manganese-enhanced MRI of retinal function

Tofts¹,

Porchia²,

Jin³

et al. 2010

Brain Research Bulletin

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Purpose-The application of Manganese-Enhanced MRI (MEMRI) to measure retinal function in humans is unclear. To begin to address this gap, we tested the hypothesis that an FDA-approved manganese-based MRI contrast agent, Teslascan, is useful for measuring functional intraretinal ionic regulation.Methods-Anesthetized dark-or light-adapted male healthy Sprague Dawley rats were infused for 30 min with 10 μmol/kg of Teslascan (clinically relevant dose; n=5), 100 μmol/kg Teslascan (n=5), or saline (n=5). Four hours post administration, high resolution MEMRI data were collected. Intraretinal signal intensities and enhancements were measured. Modelling was performed to estimate apparent retinal transfer constant K i and to determine optimal data acquisition parameters.Results-In light-adapted rats, intraretinal enhancements responded in a dose-response manner. In addition, in the outer retina the effect of light-adaptation was to reduce significantly Mn 2+ uptake and K i compared to dark-adaptation. A non-significant change was also observed in the inner retina. Modelling shows Mn 2+ plasma concentration reaching a plateau after about 2 hours. Apparent K i values for the clinically-relevant dose are 3-6 10 -3 min -1 , decreasing to 0.5-0.6 10 -3 min -1 at the higher dose. Intraretinal signal is almost linear with K i . Optimal TR for a spin echo sequence is 0.4-1.4s. Conclusion-Firsttime evidence is presented that a clinically-relevant dose and route of Teslascan can be used to measure intraretinal function. The potential for future clinical application of MEMRI in a broad range of retinopathies is high.

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QA: Quality Assurance, Accuracy, Precision and Phantoms

Cited by 24 publications

References 61 publications

Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients,in-vitroandin-vivoreproducibility

Toward clinical application of manganese-enhanced MRI of retinal function

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