| 1. |
- Berggren, Klas, et al.
(författare)
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Super-Resolution Cine Image Enhancement for Fetal Cardiac Magnetic Resonance Imaging
- 2022
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 56:1, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundFetal cardiac magnetic resonance imaging (MRI) improves the diagnosis of congenital heart defects, but is sensitive to fetal motion due to long image acquisition time. This may be overcome with faster image acquisition with low resolution, followed by image enhancement to provide clinically useful images.PurposeTo combine phase-encoding undersampling with super-resolution neural networks to achieve high-resolution fetal cine cardiac MR images with short acquisition time.Study TypeProspective.SubjectsTwenty-eight fetuses (gestational week 36 [interquartile range 33–38 weeks]).Field Strength/Sequence1.5 T, balanced steady-state free precession (bSSFP) cine sequence.AssessmentImages were acquired using fully sampled Doppler ultrasound-gated clinical bSSFP cine as reference, with equivalent cine sequences with decreased phase-encoding resolution (25%, 33%, and 50% of clinical standard). Two super-resolution methods based on convolutional neural networks were proposed and evaluated (phasrGAN and phasrresnet). Data were partitioned into training (36 cine slices), validation (3 cine slices), and test sets (67 cine slices) without overlap. Conventional reconstruction methods using bicubic interpolation and k-space zeropadding were used for comparison. Three blinded observers scored image quality between 1 and 10.Statistical TestsImage scores are reported as median [interquartile range] and were compared using Mann–Whitney's nonparametric test with P < 0.05 showing statistically significant differences.ResultsBoth proposed methods showed no significant difference in image quality compared to clinical images (8 [7–8.5]) down to 33% (phasrGAN 8 [6.5–8]; phasrresnet 8 [7–8], all P ≥ 0.19) phase-encoding resolution, i.e., up to three times faster image acquisition, whereas bicubic interpolation and k-space zeropadding showed significantly lower quality for 33% phase-encoding resolution (both 7 [6–8]).Data ConclusionSuper-resolution enhancement can be used for fetal cine cardiac MRI to reduce image acquisition time while maintaining image quality. This may lead to an improved success rate for fetal cine MR imaging, as the impact of fetal motion is lessened by shortened acquisitions.Level of Evidence1Technical EfficacyStage 2
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| 3. |
- Carlsson, Marcus, et al.
(författare)
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Quantification and visualization of cardiovascular 4D velocity mapping accelerated with parallel imaging or k-t BLAST: head to head comparison and validation at 1.5 T and 3 T
- 2011
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Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 13:55
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Tidskriftsartikel (refereegranskat)abstract
- Background: Three-dimensional time-resolved (4D) phase-contrast (PC) CMR can visualize and quantify cardiovascular flow but is hampered by long acquisition times. Acceleration with SENSE or k-t BLAST are two possibilities but results on validation are lacking, especially at 3 T. The aim of this study was therefore to validate quantitative in vivo cardiac 4D-acquisitions accelerated with parallel imaging and k-t BLAST at 1.5 T and 3 T with 2D-flow as the reference and to investigate if field strengths and type of acceleration have major effects on intracardiac flow visualization. Methods: The local ethical committee approved the study. 13 healthy volunteers were scanned at both 1.5 T and 3 T in random order with 2D-flow of the aorta and main pulmonary artery and two 4D-flow sequences of the heart accelerated with SENSE and k-t BLAST respectively. 2D-image planes were reconstructed at the aortic and pulmonary outflow. Flow curves were calculated and peak flows and stroke volumes (SV) compared to the results from 2D-flow acquisitions. Intra-cardiac flow was visualized using particle tracing and image quality based on the flow patterns of the particles was graded using a four-point scale. Results: Good accuracy of SV quantification was found using 3 T 4D-SENSE (r(2) = 0.86, -0.7 +/- 7.6%) and although a larger bias was found on 1.5 T (r(2) = 0.71, -3.6 +/- 14.8%), the difference was not significant (p = 0.46). Accuracy of 4D k-t BLAST for SV was lower (p < 0.01) on 1.5 T (r(2) = 0.65, -15.6 +/- 13.7%) compared to 3 T (r(2) = 0.64, -4.6 +/- 10.0%). Peak flow was lower with 4D-SENSE at both 3 T and 1.5 T compared to 2D-flow (p < 0.01) and even lower with 4D k-t BLAST at both scanners (p < 0.01). Intracardiac flow visualization did not differ between 1.5 T and 3 T (p = 0.09) or between 4D-SENSE or 4D k-t BLAST (p = 0.85). Conclusions: The present study showed that quantitative 4D flow accelerated with SENSE has good accuracy at 3 T and compares favourably to 1.5 T. 4D flow accelerated with k-t BLAST underestimate flow velocities and thereby yield too high bias for intra-cardiac quantitative in vivo use at the present time. For intra-cardiac 4D-flow visualization, however, 1.5 T and 3 T as well as SENSE or k-t BLAST can be used with similar quality.
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| 4. |
- Dorniak, Karolina, et al.
(författare)
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Required temporal resolution for accurate thoracic aortic pulse wave velocity measurements by phase-contrast magnetic resonance imaging and comparison with clinical standard applanation tonometry : Cardiovascular Spring Meeting
- 2016
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 16:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pulse wave velocity (PWV) is a biomarker for arterial stiffness, clinically assessed by applanation tonometry (AT). Increased use of phase-contrast cardiac magnetic resonance (CMR) imaging allows for PWV assessment with minor routine protocol additions. The aims were to investigate the acquired temporal resolution needed for accurate and precise measurements of CMR-PWV, and develop a tool for CMR-PWV measurements. Methods: Computer phantoms were generated for PWV = 2–20 m/s based on human CMR-PWV data. The PWV measurements were performed in 13 healthy young subjects and 13 patients at risk for cardiovascular disease. The CMR-PWV was measured by through-plane phase-contrast CMR in the ascending aorta and at the diaphragm level. Centre-line aortic distance was determined between flow planes. The AT-PWV was assessed within 2 h after CMR. Three observers (CMR experience: 15, 4, and <1 year) determined CMR-PWV. The developed tool was based on the flow-curve foot transit time for PWV quantification. Results: Computer phantoms showed bias 0.27 ± 0.32 m/s for a temporal resolution of at least 30 ms. Intraobserver variability for CMR-PWV were: 0 ± 0.03 m/s (15 years), -0.04 ± 0.33 m/s (4 years), and -0.02 ± 0.30 m/s (<1 year). Interobserver variability for CMR-PWV was below 0.02 ± 0.38 m/s. The AT-PWV overestimated CMR-PWV by 1.1 ± 0. 7 m/s in healthy young subjects and 1.6 ± 2.7 m/s in patients. Conclusions: An acquired temporal resolution of at least 30 ms should be used to obtain accurate and precise thoracic aortic phase-contrast CMR-PWV. A new freely available research tool was used to measure PWV in healthy young subjects and in patients, showing low intra- and interobserver variability also for less experienced CMR observers. Keywords: Aorta, Pulse wave velocity, Temporal resolution, Magnetic resonance imaging, Phase contrast, Applanation tonometry
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| 5. |
- Engblom, Henrik, et al.
(författare)
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A new automatic algorithm for quantification of myocardial infarction imaged by late gadolinium enhancement cardiovascular magnetic resonance : Experimental validation and comparison to expert delineations in multi-center, multi-vendor patient data
- 2016
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Ingår i: Journal of Cardiovascular Magnetic Resonance. - : Springer Science and Business Media LLC. - 1097-6647 .- 1532-429X. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) using magnitude inversion recovery (IR) or phase sensitive inversion recovery (PSIR) has become clinical standard for assessment of myocardial infarction (MI). However, there is no clinical standard for quantification of MI even though multiple methods have been proposed. Simple thresholds have yielded varying results and advanced algorithms have only been validated in single center studies. Therefore, the aim of this study was to develop an automatic algorithm for MI quantification in IR and PSIR LGE images and to validate the new algorithm experimentally and compare it to expert delineations in multi-center, multi-vendor patient data. Methods: The new automatic algorithm, EWA (Expectation Maximization, weighted intensity, a priori information), was implemented using an intensity threshold by Expectation Maximization (EM) and a weighted summation to account for partial volume effects. The EWA algorithm was validated in-vivo against triphenyltetrazolium-chloride (TTC) staining (n = 7 pigs with paired IR and PSIR images) and against ex-vivo high resolution T1-weighted images (n = 23 IR and n = 13 PSIR images). The EWA algorithm was also compared to expert delineation in 124 patients from multi-center, multi-vendor clinical trials 2-6 days following first time ST-elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI) (n = 124 IR and n = 49 PSIR images). Results: Infarct size by the EWA algorithm in vivo in pigs showed a bias to ex-vivo TTC of -1 ± 4%LVM (R = 0.84) in IR and -2 ± 3%LVM (R = 0.92) in PSIR images and a bias to ex-vivo T1-weighted images of 0 ± 4%LVM (R = 0.94) in IR and 0 ± 5%LVM (R = 0.79) in PSIR images. In multi-center patient studies, infarct size by the EWA algorithm showed a bias to expert delineation of -2 ± 6 %LVM (R = 0.81) in IR images (n = 124) and 0 ± 5%LVM (R = 0.89) in PSIR images (n = 49). Conclusions: The EWA algorithm was validated experimentally and in patient data with a low bias in both IR and PSIR LGE images. Thus, the use of EM and a weighted intensity as in the EWA algorithm, may serve as a clinical standard for the quantification of myocardial infarction in LGE CMR images. Clinical trial registration: CHILL-MI: NCT01379261. MITOCARE: NCT01374321.
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| 6. |
- Fransson, Helen, et al.
(författare)
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Validation of an automated method to quantify stress-induced ischemia and infarction in rest-stress myocardial perfusion SPECT.
- 2014
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1532-6551 .- 1071-3581. ; 21:3, s. 503-518
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial perfusion SPECT (MPS) is one of the frequently used methods for quantification of perfusion defects in patients with known or suspected coronary artery disease. This article describes open access software for automated quantification in MPS of stress-induced ischemia and infarction and provides phantom and in vivo validation.
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| 8. |
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| 9. |
- Jia, Xiaoming, et al.
(författare)
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Cardiac magnetic resonance evaluation of the extent of myocardial injury in patients with inferior ST elevation myocardial infarction and concomitant ST depression in leads V1-V3 : Analysis from the MITOCARE Study
- 2018
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Ingår i: Cardiology. - : S. Karger AG. - 0008-6312 .- 1421-9751. ; 140:3, s. 178-185
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Tidskriftsartikel (refereegranskat)abstract
- The aim of our study was to examine the pathophysiology of ST depression (STD) in leads V1-V3 in the setting of inferior ST elevation myocardial infarction (iSTEMI) through the perspective of cardiac magnetic resonance (CMR). Methods: Differences in myocardial area at risk (MaR), infarct size, ejection fraction and myocardial segment involvement by CMR were compared in MITOCARE trial patients with first iSTEMI with ST elevation (STE), STD or no ST changes (NST) in V1-V3. The frontal plane projection of the inferior wall MaR in relationship to the anterior/posterior chest wall was calculated and compared between groups. Results: Fifty-six patients were included. Patients with STD (n = 38) and STE (n = 5) in V1-V3 had significantly larger mean MaR compared to NST (n = 13; 32 ± 7%LV, 36 ± 10%LV and 26 ± 6%LV, respectively; p = 0.01). STD in leads V1-V3 was associated with more apical inferior and mid inferoseptal involvement and had a larger mean frontal plane projection of MaR compared with NST (24 ± 6%LV vs. 20 ± 6%LV, p = 0.04). Conclusion: STD in V1-V3 in iSTEMI is associated with larger MaR, more extension into the inferoseptal segments and likely results from greater frontal plane projection of the MaR, leading to reciprocal changes on the electrocardiogram.
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