uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Kero, Tanja
Publications (10 of 22) Show all publications
Harms, H. J., Hansson, N. H., Kero, T., Baron, T., Tolbod, L. P., Kim, W. Y., . . . Sörensen, J. (2018). Automatic calculation of myocardial external efficiency using a single 11C-acetate PET scan.. Journal of Nuclear Cardiology, 25(6), 1937-1944
Open this publication in new window or tab >>Automatic calculation of myocardial external efficiency using a single 11C-acetate PET scan.
Show others...
2018 (English)In: Journal of Nuclear Cardiology, ISSN 1071-3581, E-ISSN 1532-6551, Vol. 25, no 6, p. 1937-1944Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Myocardial external efficiency (MEE) is defined as the ratio of kinetic energy associated with cardiac work [forward cardiac output (FCO)*mean systemic pressure] and the chemical energy from oxygen consumed (MVO2) by the left ventricular mass (LVM). We developed a fully automated method for estimating MEE based on a single 11C-acetate PET scan without ECG-gating.

METHODS AND RESULTS: Ten healthy controls, 34 patients with aortic valve stenosis (AVS), and 20 patients with mitral valve regurgitation (MVR) were recruited in a dual-center study. MVO2 was calculated using washout of 11C -acetate activity. FCO and LVM were calculated automatically using dynamic PET and parametric image formation. FCO and LVM were also obtained using cardiac magnetic resonance (CMR) in all subjects. The correlation between MEEPET-CMR and MEEPET was high (r = 0.85, P < 0.001) without significant bias. MEEPET was 23.6 ± 4.2% for controls and was lowered in AVS (17.2 ± 4.3%, P < 0.001) and in MVR (18.0 ± 5.2%, P = 0.004). MEEPET was strongly associated with both NYHA class (P < 0.001) and the magnitude of valvular dysfunction (mean aortic gradient: P < 0.001, regurgitant fraction: P = 0.009).

CONCLUSION: A single 11C-acetate PET yields accurate and automated MEE results on different scanners. MEE might provide an unbiased measurement of the phenotypic response to valvular disease.

Keywords
11C-acetate, Myocardial efficiency, myocardial energetics, positron emission tomography
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-356783 (URN)10.1007/s12350-018-1338-0 (DOI)000452340400009 ()29946824 (PubMedID)
Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2019-04-17Bibliographically approved
Kero, T. (2018). Methodological aspects of quantitative cardiac molecular imaging. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Methodological aspects of quantitative cardiac molecular imaging
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this research was to facilitate the use of quantitative cardiac molecular imaging by developing and validating methods and applications. More specifically:

we determined the optimal tracer kinetic model for analysis of 11C-PIB and evaluated the performance of two simpler measures, retention index (RI) and standardized uptake value (SUV), in the quantification of cardiac 11C-PIB uptake in amyloidosis. An irreversible two-tissue (2Tirr) model best described the 11C-PIB uptake in cardiac amyloidosis. RI and SUV showed high correlation with quantitative results from this kinetic model and also a better discrimination between amyloidosis patients and controls than a 2Tirr model with population averaged metabolite correction. RI and SUV are furthermore more feasible for use in clinical routine and therefore the preferred measure to use in PET diagnosis of cardiac amyloidosis. We also tested the feasibility of a semiautomatic software to analyze RI and visualize cardiac uptake of 11C-PIB in amyloidosis. The RI values were comparable with RI based on manual segmentation, showing significantly higher 11C-PIB RI in amyloidosis patients than in healthy volunteers. A fast and accurate semiautomatic analysis process is thus feasible to use for PET in cardiac amyloidosis instead of the laborious manual analyses that were used so far.

Furthermore, we assessed the quantitative accuracy of cardiac perfusion measurements with 15O-water PET in a digital time-of-flight PET-MR scanner. A high correlation and agreement between PET-MR based and PET-CT based MBF was found; cardiac perfusion measurements with 15O-water can therefore be performed accurately with the fully integrated Signa PET-MR scanner. 

Finally, we assessed the quantitative accuracy of cardiac perfusion measurements using dynamic contrast-enhanced MRI with simultaneous 15O-water PET as reference at rest and during adenosine-induced hyperemia with a fully integrated PET-MR scanner. The correlations between global and regional MRI- and PET-based MBF values were good and the biases were negliable for both global and regional MBF comparisons, but the limits of agreement were wide for both global and regional MBF, with larger variability for high MBF-values indicating that MRI-based quantitative MBF measurement based on widely available acquisition protocols is not yet ready for clinical introduction.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 84
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1484
Keywords
PET, cardiac amyloidosis, 11C-PIB, retention index, standardized uptake value, PET-MR, MRI, myocardial blood flow, 15O-water, quantification, quantitative modeling
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-356721 (URN)978-91-513-0404-5 (ISBN)
Public defence
2018-09-28, Skoogsalen, ing 78/79, Akademiska sjukhuset, Sjukhusvägen 5B, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2018-09-07 Created: 2018-08-05 Last updated: 2018-10-02
Kero, T., Lubberink, M., Knuuti, J. & Sörensen, J. (2018). Quantitative myocardial perfusion response to adenosine and regadenoson in patients with suspected coronary artery disease measured with O-15-water PET. Paper presented at 31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY. European Journal of Nuclear Medicine and Molecular Imaging, 45, S91-S92
Open this publication in new window or tab >>Quantitative myocardial perfusion response to adenosine and regadenoson in patients with suspected coronary artery disease measured with O-15-water PET
2018 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 45, p. S91-S92Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2018
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-372964 (URN)000449266200161 ()
Conference
31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-14Bibliographically approved
Nordström, J., Harms, H. J., Lubberink, M., Tolbod, L., van den Berg, J., Baron, T., . . . Sörensen, J. (2017). Automatic extraction of left ventricular mass and volumes using parametric images from non-ECG-gated 15O-water PET/CT. European Journal of Nuclear Medicine and Molecular Imaging, 44, S302-S302
Open this publication in new window or tab >>Automatic extraction of left ventricular mass and volumes using parametric images from non-ECG-gated 15O-water PET/CT
Show others...
2017 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 44, p. S302-S302Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2017
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-377084 (URN)000455019400355 ()
Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-04-17Bibliographically approved
Nordström, J., Kero, T., Harms, H. J., Widström, C., Flachskampf, F., Sörensen, J. & Lubberink, M. (2017). Calculation of left ventricular volumes and ejection fraction from dynamic cardiac-gated 15O-water PET/CT: 5D-PET. EJNMMI Physics, 4(1), 26, Article ID 26.
Open this publication in new window or tab >>Calculation of left ventricular volumes and ejection fraction from dynamic cardiac-gated 15O-water PET/CT: 5D-PET
Show others...
2017 (English)In: EJNMMI Physics, ISSN 2197-7364, E-ISSN 2191-219X, Vol. 4, no 1, p. 26-, article id 26Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Quantitative measurement of myocardial blood flow (MBF) is of increasing interest in the clinical assessment of patients with suspected coronary artery disease (CAD). (15)O-water positron emission tomography (PET) is considered the gold standard for non-invasive MBF measurements. However, calculation of left ventricular (LV) volumes and ejection fraction (EF) is not possible from standard (15)O-water uptake images. The purpose of the present work was to investigate the possibility of calculating LV volumes and LVEF from cardiac-gated parametric blood volume (V B) (15)O-water images and from first pass (FP) images. Sixteen patients with mitral or aortic regurgitation underwent an eight-gate dynamic cardiac-gated (15)O-water PET/CT scan and cardiac MRI. V B and FP images were generated for each gate. Calculations of end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV) and LVEF were performed with automatic segmentation of V B and FP images, using commercially available software. LV volumes and LVEF were calculated with surface-, count-, and volume-based methods, and the results were compared with gold standard MRI.

RESULTS: Using V B images, high correlations between PET and MRI ESV (r = 0.89, p < 0.001), EDV (r = 0.85, p < 0.001), SV (r = 0.74, p = 0.006) and LVEF (r = 0.72, p = 0.008) were found for the volume-based method. Correlations for FP images were slightly, but not significantly, lower than those for V B images when compared to MRI. Surface- and count-based methods showed no significant difference compared with the volume-based correlations with MRI. The volume-based method showed the best agreement with MRI with no significant difference on average for EDV and LVEF but with an overestimation of values for ESV (14%, p = 0.005) and SV (18%, p = 0.004) when using V B images. Using FP images, none of the parameters showed a significant difference from MRI. Inter-operator repeatability was excellent for all parameters (ICC > 0.86, p < 0.001).

CONCLUSION: Calculation of LV volumes and LVEF from dynamic (15)O-water PET is feasible and shows good correlation with MRI. However, the analysis method is laborious, and future work is needed for more automation to make the method more easily applicable in a clinical setting.

National Category
Cardiac and Cardiovascular Systems Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-333781 (URN)10.1186/s40658-017-0195-2 (DOI)000415372700001 ()29138942 (PubMedID)
Available from: 2017-11-16 Created: 2017-11-16 Last updated: 2019-01-28Bibliographically approved
Kero, T., Nordström, J., Harms, H. J., Sörensen, J., Ahlström, H. & Lubberink, M. (2017). Quantitative myocardial blood flow imaging with integrated time-of-flight PET-MR. EJNMMI physics, 4(1)
Open this publication in new window or tab >>Quantitative myocardial blood flow imaging with integrated time-of-flight PET-MR
Show others...
2017 (English)In: EJNMMI physics, ISSN 2197-7364, Vol. 4, no 1Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The use of integrated PET-MR offers new opportunities for comprehensive assessment of cardiac morphology and function. However, little is known on the quantitative accuracy of cardiac PET imaging with integrated time-of-flight PET-MR. The aim of the present work was to validate the GE Signa PET-MR scanner for quantitative cardiac PET perfusion imaging. Eleven patients (nine male; mean age 59 years; range 46-74 years) with known or suspected coronary artery disease underwent (15)O-water PET scans at rest and during adenosine-induced hyperaemia on a GE Discovery ST PET-CT and a GE Signa PET-MR scanner. PET-MR images were reconstructed using settings recommended by the manufacturer, including time-of-flight (TOF). Data were analysed semi-automatically using Cardiac VUer software, resulting in both parametric myocardial blood flow (MBF) images and segment-based MBF values. Correlation and agreement between PET-CT-based and PET-MR-based MBF values for all three coronary artery territories were assessed using regression analysis and intra-class correlation coefficients (ICC). In addition to the cardiac PET-MR reconstruction protocol as recommended by the manufacturer, comparisons were made using a PET-CT resolution-matched reconstruction protocol both without and with TOF to assess the effect of time-of-flight and reconstruction parameters on quantitative MBF values.

RESULTS: Stress MBF data from one patient was excluded due to movement during the PET-CT scanning. Mean MBF values at rest and stress were (0.92 ± 0.12) and (2.74 ± 1.37) mL/g/min for PET-CT and (0.90 ± 0.23) and (2.65 ± 1.15) mL/g/min for PET-MR (p = 0.33 and p = 0.74). ICC between PET-CT-based and PET-MR-based regional MBF was 0.98. Image quality was improved with PET-MR as compared to PET-CT. ICC between PET-MR-based regional MBF with and without TOF and using different filter and reconstruction settings was 1.00.

CONCLUSIONS: PET-MR-based MBF values correlated well with PET-CT-based MBF values and the parametric PET-MR images were excellent. TOF and reconstruction settings had little impact on MBF values.

Keywords
PET-MR, Myocardial blood flow (MBF), O-15-water, Quantification, Time-of-flight (TOF)
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-312386 (URN)10.1186/s40658-016-0171-2 (DOI)000397119200001 ()28058674 (PubMedID)
Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2018-08-05Bibliographically approved
Baron, T., Orndahl, L. H., Kero, T., Sörensen, J., Bjerner, T., Hedin, E.-M., . . . Flachskampf, F. (2017). Volumetric quantification of regurgitant volume in asymptomatic severe degenerative mitral regurgitation by echocardiography and cardiac mri with independent validation of forward stroke volume by positron emission tomography. Paper presented at 66th Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC), MAR 17-19, 2017, Washington, DC. Journal of the American College of Cardiology, 69(11 Suppl), 1973-1973
Open this publication in new window or tab >>Volumetric quantification of regurgitant volume in asymptomatic severe degenerative mitral regurgitation by echocardiography and cardiac mri with independent validation of forward stroke volume by positron emission tomography
Show others...
2017 (English)In: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597, Vol. 69, no 11 Suppl, p. 1973-1973Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
ELSEVIER SCIENCE INC, 2017
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-321054 (URN)10.1016/S0735-1097(17)35362-7 (DOI)000397342302695 ()
Conference
66th Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC), MAR 17-19, 2017, Washington, DC
Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2019-04-17Bibliographically approved
Kero, T., Lindsjö, L., Sörensen, J. & Lubberink, M. (2016). Accurate analysis and visualization of cardiac (11)C-PIB uptake in amyloidosis with semiautomatic software. Journal of Nuclear Cardiology, 23(4), 741-750
Open this publication in new window or tab >>Accurate analysis and visualization of cardiac (11)C-PIB uptake in amyloidosis with semiautomatic software
2016 (English)In: Journal of Nuclear Cardiology, ISSN 1071-3581, E-ISSN 1532-6551, Vol. 23, no 4, p. 741-750Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: (11)C-PIB PET is a promising non-invasive diagnostic tool for cardiac amyloidosis. Semiautomatic analysis of PET data is now available but it is not known how accurate these methods are for amyloid imaging. The aim of this study was to evaluate the feasibility of one semiautomatic software tool for analysis and visualization of (11)C-PIB left ventricular retention index (RI) in cardiac amyloidosis.

METHODS AND RESULTS: Patients with systemic amyloidosis and cardiac involvement (n = 10) and healthy controls (n = 5) were investigated with dynamic (11)C-PIB PET. Two observers analyzed the PET studies with semiautomatic software to calculate the left ventricular RI of (11)C-PIB and to create parametric images. The mean RI at 15-25 min from the semiautomatic analysis was compared with RI based on manual analysis and showed comparable values (0.056 vs 0.054 min(-1) for amyloidosis patients and 0.024 vs 0.025 min(-1) in healthy controls; P = .78) and the correlation was excellent (r = 0.98). Inter-reader reproducibility also was excellent (intraclass correlation coefficient, ICC > 0.98). Parametric polarmaps and histograms made visual separation of amyloidosis patients and healthy controls fast and simple.

CONCLUSION: Accurate semiautomatic analysis of cardiac (11)C-PIB RI in amyloidosis patients is feasible. Parametric polarmaps and histograms make visual interpretation fast and simple.

Keywords
Amyloid; PET imaging; C-11 PIB; cardiac amyloidosis
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-266308 (URN)10.1007/s12350-015-0149-9 (DOI)000381082100016 ()26173894 (PubMedID)
Available from: 2015-11-06 Created: 2015-11-06 Last updated: 2018-08-05Bibliographically approved
Baron, T., Örndahl, L. H., Kero, T., Sörensen, J., Bjerner, T., Hedin, E.-M., . . . Flachskampf, F. A. (2016). Comparison of left ventricular volumes and regurgitant volumes by echocardiography and magnetic resonance in patients with severe degenerative mitral regurgitation. Paper presented at Congress of the European-Society-of-Cardiology (ESC), AUG 27-31, 2016, Rome, ITALY. European Heart Journal, 37, 1239-1239
Open this publication in new window or tab >>Comparison of left ventricular volumes and regurgitant volumes by echocardiography and magnetic resonance in patients with severe degenerative mitral regurgitation
Show others...
2016 (English)In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 37, p. 1239-1239Article in journal, Meeting abstract (Refereed) Published
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:uu:diva-313883 (URN)000383869506148 ()
Conference
Congress of the European-Society-of-Cardiology (ESC), AUG 27-31, 2016, Rome, ITALY
Available from: 2017-01-25 Created: 2017-01-25 Last updated: 2019-04-17Bibliographically approved
Harms, H. J., Tolbod, L. P., Hansson, N. H., Kero, T., Örndahl, L. H., Kim, W. Y., . . . Sörensen, J. (2015). Automatic extraction of forward stroke volume using dynamic PET/CT: a dual-tracer and dual-scanner validation in patients with heart valve disease.. EJNMMI physics, 2(1), Article ID 25.
Open this publication in new window or tab >>Automatic extraction of forward stroke volume using dynamic PET/CT: a dual-tracer and dual-scanner validation in patients with heart valve disease.
Show others...
2015 (English)In: EJNMMI physics, ISSN 2197-7364, Vol. 2, no 1, article id 25Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The aim of this study was to develop and validate an automated method for extracting forward stroke volume (FSV) using indicator dilution theory directly from dynamic positron emission tomography (PET) studies for two different tracers and scanners.

METHODS: 35 subjects underwent a dynamic (11)C-acetate PET scan on a Siemens Biograph TruePoint-64 PET/CT (scanner I). In addition, 10 subjects underwent both dynamic (15)O-water PET and (11)C-acetate PET scans on a GE Discovery-ST PET/CT (scanner II). The left ventricular (LV)-aortic time-activity curve (TAC) was extracted automatically from PET data using cluster analysis. The first-pass peak was isolated by automatic extrapolation of the downslope of the TAC. FSV was calculated as the injected dose divided by the product of heart rate and the area under the curve of the first-pass peak. Gold standard FSV was measured using phase-contrast cardiovascular magnetic resonance (CMR).

RESULTS: FSVPET correlated highly with FSVCMR (r = 0.87, slope = 0.90 for scanner I, r = 0.87, slope = 1.65, and r = 0.85, slope = 1.69 for scanner II for (15)O-water and (11)C-acetate, respectively) although a systematic bias was observed for both scanners (p < 0.001 for all). FSV based on (11)C-acetate and (15)O-water correlated highly (r = 0.99, slope = 1.03) with no significant difference between FSV estimates (p = 0.14).

CONCLUSIONS: FSV can be obtained automatically using dynamic PET/CT and cluster analysis. Results are almost identical for (11)C-acetate and (15)O-water. A scanner-dependent bias was observed, and a scanner calibration factor is required for multi-scanner studies. Generalization of the method to other tracers and scanners requires further validation.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-268064 (URN)10.1186/s40658-015-0133-0 (DOI)000379208500025 ()26501826 (PubMedID)
Available from: 2015-12-02 Created: 2015-12-02 Last updated: 2016-08-10Bibliographically approved
Organisations

Search in DiVA

Show all publications