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"Lawton, Chris"
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T1 mapping performance and measurement repeatability: results from the multi-national T1 mapping standardization phantom program (T1MES)
2020
Background
The
T
1
Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored
T
1
mapping quality assurance using a purpose-developed phantom with Food and Drug Administration (FDA) and Conformité Européenne (CE) regulatory clearance. We report
T
1
measurement repeatability across centers describing sequence, magnet, and vendor performance.
Methods
Phantoms batch-manufactured in August 2015 underwent 2 years of structural imaging,
B
0
and
B
1
, and “reference” slow
T
1
testing. Temperature dependency was evaluated by the United States National Institute of Standards and Technology and by the German Physikalisch-Technische Bundesanstalt. Center-specific
T
1
mapping repeatability (maximum one scan per week to minimum one per quarter year) was assessed over mean 358 (maximum 1161) days on 34 1.5 T and 22 3 T magnets using multiple
T
1
mapping sequences. Image and temperature data were analyzed semi-automatically. Repeatability of serial
T
1
was evaluated in terms of coefficient of variation (CoV), and linear mixed models were constructed to study the interplay of some of the known sources of
T
1
variation.
Results
Over 2 years, phantom gel integrity remained intact (no rips/tears),
B
0
and
B
1
homogenous, and “reference”
T
1
stable compared to baseline (% change at 1.5 T, 1.95 ± 1.39%; 3 T, 2.22 ± 1.44%). Per degrees Celsius, 1.5 T,
T
1
(MOLLI 5s(3s)3s) increased by 11.4 ms in long native blood tubes and decreased by 1.2 ms in short post-contrast myocardium tubes. Agreement of estimated
T
1
times with “reference”
T
1
was similar across Siemens and Philips CMR systems at both field strengths (adjusted
R
2
ranges for both field strengths, 0.99–1.00). Over 1 year, many 1.5 T and 3 T sequences/magnets were repeatable with mean CoVs < 1 and 2% respectively. Repeatability was narrower for 1.5 T over 3 T. Within T1MES repeatability for native
T
1
was narrow for several sequences, for example, at 1.5 T, Siemens MOLLI 5s(3s)3s prototype number 448B (mean CoV = 0.27%) and Philips modified Look-Locker inversion recovery (MOLLI) 3s(3s)5s (CoV 0.54%), and at 3 T, Philips MOLLI 3b(3s)5b (CoV 0.33%) and Siemens shortened MOLLI (ShMOLLI) prototype 780C (CoV 0.69%). After adjusting for temperature and field strength, it was found that the
T
1
mapping sequence and scanner software version (both
P
< 0.001 at 1.5 T and 3 T), and to a lesser extent the scanner model (
P
= 0.011, 1.5 T only), had the greatest influence on
T
1
across multiple centers.
Conclusion
The T1MES CE/FDA approved phantom is a robust quality assurance device. In a multi-center setting,
T
1
mapping had performance differences between field strengths, sequences, scanner software versions, and manufacturers. However, several specific combinations of field strength, sequence, and scanner are highly repeatable, and thus, have potential to provide standardized assessment of
T
1
times for clinical use, although temperature correction is required for native
T
1
tubes at least.
Journal Article
T 1 mapping performance and measurement repeatability: results from the multi-national T 1 mapping standardization phantom program (T1MES)
by
Moon, James C
,
Steeds, Richard
,
Barison, Andrea
in
Calibration
,
Consensus
,
Extracellular volume
2020
The T
Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored T
mapping quality assurance using a purpose-developed phantom with Food and Drug Administration (FDA) and Conformité Européenne (CE) regulatory clearance. We report T
measurement repeatability across centers describing sequence, magnet, and vendor performance.
Phantoms batch-manufactured in August 2015 underwent 2 years of structural imaging, B
and B
, and \"reference\" slow T
testing. Temperature dependency was evaluated by the United States National Institute of Standards and Technology and by the German Physikalisch-Technische Bundesanstalt. Center-specific T
mapping repeatability (maximum one scan per week to minimum one per quarter year) was assessed over mean 358 (maximum 1161) days on 34 1.5 T and 22 3 T magnets using multiple T
mapping sequences. Image and temperature data were analyzed semi-automatically. Repeatability of serial T
was evaluated in terms of coefficient of variation (CoV), and linear mixed models were constructed to study the interplay of some of the known sources of T
variation.
Over 2 years, phantom gel integrity remained intact (no rips/tears), B
and B
homogenous, and \"reference\" T
stable compared to baseline (% change at 1.5 T, 1.95 ± 1.39%; 3 T, 2.22 ± 1.44%). Per degrees Celsius, 1.5 T, T
(MOLLI 5s(3s)3s) increased by 11.4 ms in long native blood tubes and decreased by 1.2 ms in short post-contrast myocardium tubes. Agreement of estimated T
times with \"reference\" T
was similar across Siemens and Philips CMR systems at both field strengths (adjusted R
ranges for both field strengths, 0.99-1.00). Over 1 year, many 1.5 T and 3 T sequences/magnets were repeatable with mean CoVs < 1 and 2% respectively. Repeatability was narrower for 1.5 T over 3 T. Within T1MES repeatability for native T
was narrow for several sequences, for example, at 1.5 T, Siemens MOLLI 5s(3s)3s prototype number 448B (mean CoV = 0.27%) and Philips modified Look-Locker inversion recovery (MOLLI) 3s(3s)5s (CoV 0.54%), and at 3 T, Philips MOLLI 3b(3s)5b (CoV 0.33%) and Siemens shortened MOLLI (ShMOLLI) prototype 780C (CoV 0.69%). After adjusting for temperature and field strength, it was found that the T
mapping sequence and scanner software version (both P < 0.001 at 1.5 T and 3 T), and to a lesser extent the scanner model (P = 0.011, 1.5 T only), had the greatest influence on T
across multiple centers.
The T1MES CE/FDA approved phantom is a robust quality assurance device. In a multi-center setting, T
mapping had performance differences between field strengths, sequences, scanner software versions, and manufacturers. However, several specific combinations of field strength, sequence, and scanner are highly repeatable, and thus, have potential to provide standardized assessment of T
times for clinical use, although temperature correction is required for native T
tubes at least.
Journal Article
Society for Cardiovascular Magnetic Resonance (SCMR) guidance for the practice of cardiovascular magnetic resonance during the COVID-19 pandemic
by
Dyke, Christopher
,
Elliott, Michael D.
,
Raman, Subha V.
in
Angiology
,
Betacoronavirus
,
Cardiology
2020
The aim of this document is to provide general guidance and specific recommendations on the practice of cardiovascular magnetic resonance (CMR) in the era of the COVID-19 pandemic. There are two major considerations. First, continued urgent and semi-urgent care for the patients who have no known active COVID-19 should be provided in a safe manner for both patients and staff. Second, when necessary, CMR on patients with confirmed or suspected active COVID-19 should focus on the specific clinical question with an emphasis on myocardial function and tissue characterization while optimizing patient and staff safety.
Journal Article
Microvascular dysfunction determines infarct characteristics in patients with reperfused ST-segment elevation myocardial infarction: The MICROcirculation in Acute Myocardial Infarction (MICRO-AMI) study
by
Baumbach, Andreas
,
McAlindon, Elisa
,
Strange, Julian
in
Adenosine
,
Angioplasty
,
Biology and Life Sciences
2018
In patients with reperfused ST-elevation myocardial infarction (STEMI) both invasive and non-invasive assessments of microvascular dysfunction, the index of microcirculatory resistance (IMR), and microvascular obstruction (MVO) by cardiovascular magnetic resonance (CMR), independently predict poor long-term outcomes.
The aims of this study were to investigate whether an invasive parameter (IMR), assessed at the time of primary percutaneous intervention (PPCI), could predict the extent of MVO in proportion to infarct size (MVO index).
50 patients presenting with STEMI and TIMI flow ≤ I in the infarct related artery were prospectively recruited to the study, before undergoing PPCI. All patients underwent invasive IMR assessment at maximal hyperaemia using adenosine, and following stent insertion. CMR was performed on day 2 following STEMI, MVO was assessed both on first-pass rest perfusion (early MVO) and in the late gadolinium enhancement (LGE) images (late MVO) along with infarct size. The MVO index was calculated as the ratio of late MVO/infarct size. Differences between IMR quartiles and the MVO index were investigated.
The median IMR was 38.5 (range 9 to 202). The median size of late MVO was 1.9% LV (range 0 to 21.0% LV). IMR predicted late MVO (p<0.01) and as IMR increased, the MVO index increased (r = 0.70, [95% CI 0.53, 0.82], p<0.001). An IMR cut-off of 40 significantly predicted the presence of late MVO on CMR (p<0.001).
IMR measured at the time of PPCI in acutely reperfused STEMI is associated with the presence and severity of infarct damage as measured by the MVO index.
The Microcirculation in Acute Myocardial Infarction (MICRO-AMI). Clinicaltrials.gov NCT01552564. Registered 9th March 2012.
Journal Article
Society for Cardiovascular Magnetic Resonance (SCMR) guidance for re-activation of cardiovascular magnetic resonance practice after peak phase of the COVID-19 pandemic
by
Dall’Armellina, Erica
,
Salerno, Michael
,
Raman, Subha V.
in
Activation
,
Angiology
,
Betacoronavirus
2020
During the peak phase of the COVID-19 pandemic, alterations of standard operating procedures were necessary for health systems to protect patients and healthcare workers and ensure access to vital hospital resources. As the peak phase passes, re-activation plans are required to safely manage increasing clinical volumes. In the context of cardiovascular magnetic resonance (CMR), re-activation objectives include continued performance of urgent CMR studies and resumption of CMR in patients with semi-urgent and elective indications in an environment that is safe for both patients and health care workers.
Journal Article
Society for cardiovascular magnetic resonance recommendations for training and competency of CMR technologists
by
Dyke, Christopher
,
Raman, Subha
,
Elliott, Michael D.
in
Angiology
,
Cardiology
,
Cardiomyopathy
2022
The Society for Cardiovascular Magnetic Resonance (SCMR) recommendations for training and competency of cardiovascular magnetic resonance (CMR) technologists document will define the knowledge, experiences and skills required for a technologist to be competent in CMR imaging. By providing a framework for CMR training and competency the overarching goal is to promote the performance of high-quality CMR and to foster the increased adoption of CMR into clinical care.
Journal Article