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Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences.
Ryhov County Hospital.
Ryhov County Hospital.
Ryhov County Hospital.
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2010 (English)In: CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, ISSN 1475-0961, Vol. 30, no 2, 122-129 p.Article in journal (Refereed) Published
Abstract [en]

Pandgt;Background: Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction. Methods: Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed. Results: SS_SSFP had significantly better quality scores in all categories (P = 0 center dot 037, P = 0 center dot 014, P = 0 center dot 021, P = 0 center dot 03). SNRinfarct and SNRblood were significantly better for IR_FGRE than for SS_SSFP (P = 0 center dot 048, P = 0 center dot 018). No significant difference was found in SNRmyocardium and CNR. The myocardial volume was significantly larger with SS_SSFP (170 center dot 7 versus 159 center dot 2 ml, P andlt; 0 center dot 001), but no significant difference was found in infarct volume and infarct extent. Conclusion: SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.

Place, publisher, year, edition, pages
2010. Vol. 30, no 2, 122-129 p.
Keyword [en]
atrial fibrillation, magnetic resonance imaging, myocardial infarction, segmented inversion recovery 2D fast gradient echo, single shot inversion recovery 2D steady-state free precession
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-54159DOI: 10.1111/j.1475-097X.2009.00914.xISI: 000274438800006OAI: oai:DiVA.org:liu-54159DiVA: diva2:300386
Available from: 2010-02-26 Created: 2010-02-26 Last updated: 2016-08-24
In thesis
1. Infarct size and myocardial function: A methodological study
Open this publication in new window or tab >>Infarct size and myocardial function: A methodological study
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The size of a myocardial infarction (MI) and the concurrent effect on left ventricular (LV) function are essential for decisions regarding patient care and treatment. Images produced with the late gadolinium enhancement (LGE) technique visualize the scar with high spatial resolution. The general aim of this thesis was to study methods to assess scar size in chronic MI, primarily with the use of LGE, and to relate area‐at‐risk and LV function to scar size.

Myocardial perfusion single photon emission computed tomography (MPS) is a well established technique for the assessment of MI size. Our study showed that there is a fairly good agreement between MPS and LGE in the determination of scar size. Wall motion score index (WMSI) correlated moderately with both infarct size and infarct extent determined with LGE.

Manual delineation of myocardium and scar is time consuming and subjective and there is a need for help in objective assessment. We showed that the semi‐automatic computer software, Segment, reduced the evaluation time ≥50% with maintained clinical accuracy.

The segmented scar sequence ‐ inversion recovery fast gradient echo, IR_FGRE, is a well documented sequence for scar determination, however, the sequence requires regular heart rhythm and breath holding for good imaging. We showed that a single shot scar sequence ‐ steady state free precession, SS_SSFP ‐ acquired under free breathing in patients with ongoing atrial fibrillation, had significantly better image quality than IR_FGRE. The scar size and the error of determination were equal for both sequences and the examination time was shorter with SS_SSFP.

In an acute MI it is essential to know the myocardial area‐at‐risk. WMSI is clinically the most common way of assessing LV function, but is highly subjective. Tissue Doppler imaging with strain measurements is considered objective and quantitative in assessing both global and regional LV function compared to WMSI. Our results showed that WMSI is superior to strain for the detection of scar with transmurality ≥50% in patients with acute MI. Also WMSI correlated better than strain on all levels (global, regional, segmental) with final scar size determined with LGE.

LGE images visualize myocardial scar much more distinctly than any other modality. This new technique needs clinical validation but promises intense competition with existing modalities such as myocardial scintigraphy and echocardiography.

However, in individual patient care all modalities should be used according to their own advantages and limitation.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 85 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1169
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-53943 (URN)9789173934374 (ISBN)
Public defence
2010-03-26, Originalet, Qulturum, Hus B4, Länssjukhuset Ryhov, Jönköping, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2010-03-09 Created: 2010-02-15 Last updated: 2017-12-13Bibliographically approved
2. Magnetic Resonance Imaging of the Heart: Image quality, measurement accuracy and patient experience
Open this publication in new window or tab >>Magnetic Resonance Imaging of the Heart: Image quality, measurement accuracy and patient experience
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Non-invasive diagnostic imaging of atherosclerotic coronary artery disease (CAD) is frequently carried out with cardiovascular magnetic resonance imaging (CMR) or myocardial perfusion single photon emission computed tomography (MPS). CMR is the gold standard for the evaluation of scar after myocardial infarction and MPS the clinical gold standard for ischemia. Magnetic Resonance Imaging (MRI) is at times difficult for patients and may induce anxiety while patient experience of MPS is largely unknown.

Aims: To evaluate image quality in CMR with respect to the sequences employed, the influence of atrial fibrillation, myocardial perfusion and the impact of patient information. Further, to study patient experience in relation to MRI with the goal of improving the care of these patients.

Method: Four study designs have been used. In paper I, experimental cross-over, paper (II) experimental controlled clinical trial, paper (III) psychometric crosssectional study and paper (IV) prospective intervention study. A total of 475 patients ≥ 18 years with primarily cardiac problems (I-IV) except for those referred for MRI of the spine (III) were included in the four studies.

Result: In patients (n=20) with atrial fibrillation, a single shot steady state free precession (SS-SSFP) sequence showed significantly better image quality than the standard segmented inversion recovery fast gradient echo (IR-FGRE) sequence (I). In first-pass perfusion imaging the gradient echo-echo planar imaging sequence (GREEPI) (n=30) had lower signal-to-noise and contrast–to-noise ratios than the steady state free precession sequence (SSFP) (n=30) but displayed a higher correlation with the MPS results, evaluated both qualitatively and quantitatively (II). The MRIAnxiety Questionnaire (MRI-AQ) was validated on patients, referred for MRI of either the spine (n=193) or the heart (n=54). The final instrument had 15 items divided in two factors regarding Anxiety and Relaxation. The instrument was found to have satisfactory psychometric properties (III). Patients who prior CMR viewed an information video scored significantly (lower) better in the factor Relaxation, than those who received standard information. Patients who underwent MPS scored lower on both factors, Anxiety and Relaxation. The extra video information had no effect on CMR image quality (IV).

Conclusion: Single shot imaging in atrial fibrillation produced images with less artefact than a segmented sequence. In first-pass perfusion imaging, the sequence GRE-EPI was superior to SSFP. A questionnaire depicting anxiety during MRI showed that video information prior to imaging helped patients relax but did not result in an improvement in image quality.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. 74 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1524
National Category
Radiology, Nuclear Medicine and Medical Imaging Medical Image Processing Cardiac and Cardiovascular Systems Medical Laboratory and Measurements Technologies Family Medicine
Identifiers
urn:nbn:se:liu:diva-130796 (URN)10.3384/diss.diva-130796 (DOI)9789176857427 (ISBN)
Public defence
2016-09-30, Originalet, Qulturum, Hus B4, Länssjukhuset Ryhov, Jönköping, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2016-08-24 Created: 2016-08-24 Last updated: 2016-08-29Bibliographically approved

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Rosendahl, LeneBrudin, LarsEngvall, Jan

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