PET/CT imaging: Effect of respiratory motion on apparent myocardial uptake

Meunier, Ludovic Le; Maass‐Moreno, Roberto; Carrasquillo, Jorge A.; Dieckmann, William J.; Bacharach, Stephen L.

doi:10.1016/j.nuclcard.2006.09.003

Cited by 86 publications

(57 citation statements)

References 12 publications

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“…Inconsistencies between a CT attenuation correction map from a single respiratory phase and a temporally averaged PET study imaged over many breathing periods may lead to errors in the final attenuation-corrected image (10). This respirationinduced misregistration between the PET and CT scans has brought about increased interest in methods to correct for artifacts from respiratory motion (6,(10)(11)(12)(13)(14)(15)(16).…”

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confidence: 99%

“…Errors resulting from the PET/CT data mismatch can seriously affect the count levels in the reconstructed heart image (14). Studies of simulations (10), canines (14), and humans (15) have shown that attenuation correction based on CT scans acquired at a single phase of the respiratory cycle, such as at end-expiration or end-inspiration, leads to incorrect calculated levels of heart activity. Additionally, these errors are also seen clinically in 18 F-FDG PET studies corrected with a standard helical CT scan (16,17), possibly leading to a change in diagnosis or treatment of the patient (18).…”

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confidence: 99%

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Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Cook¹,

Carnes²,

Lee³

et al. 2007

Journal of Nuclear Medicine

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Heart disease is a leading cause of death in North America. With the increased availability of PET/CT scanners, CT is now commonly used as a transmission source for attenuation correction. Because of the differences in scan duration between PET and CT, respiration-induced motion can create inconsistencies between the PET and CT data and lead to incorrect attenuation correction and, thus, artifacts in the final reconstructed PET images. This study compared respiration-averaged CT and 4-dimensional (4D) CT for attenuation correction of cardiac PET in an in vivo canine model as a means of removing these inconsistencies. Methods: Five dogs underwent respiration-gated cardiac 18 F-FDG PET and 4D CT. The PET data were reconstructed with 3 methods of attenuation correction that differed only in the CT data used: The first method was single-phase CT at either end-expiration, end-inspiration, or the middle of a breathing cycle; the second was respiration-averaged CT, which is CT temporally averaged over the entire respiratory cycle; and the third was phase-matched CT, in which each PET phase is corrected with the matched phase from 4D CT. After reconstruction, the gated PET images were summed to produce an ungated image. Polar plots of the PET heart images were generated, and percentage differences were calculated with respect to the phase-matched correction for each dog. The difference maps were then averaged over the 5 dogs. Results: For single-phase CT correction at end-expiration, end-inspiration, and mid cycle, the maximum percentage differences were 11% 6 4%, 7% 6 3%, and 5% 6 2%, respectively. Conversely, the maximum difference for attenuation correction with respiration-averaged CT data was only 1.6% 6 0.7%. Conclusion: Respirationaveraged CT correction produced a maximum percentage difference 7 times smaller than that obtained with end-expiration single-phase correction. This finding indicates that using respiration-averaged CT may accurately correct for attenuation on respiration-ungated cardiac PET.

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confidence: 99%

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confidence: 99%

Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Cook¹,

Carnes²,

Lee³

et al. 2007

Journal of Nuclear Medicine

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“…Moreover, variable attenuation correction associated with respiratory motion causes marked heterogeneity in quantitative measurements of relative and absolute myocardial radionuclide uptake (5). Therefore, measurements of absolute myocardial perfusion in cm 3 /min/g by PET/CT is appropriate only if the primary radionuclide update data are correctly obtained using cine or shifted cine CT attenuation correction that matches the average attenuation structures of emission data obtained over longer times during breathing.…”

Section: Discussionmentioning

confidence: 99%

“…Frequent misregistration artifacts in standard cardiac PET/CT using helical CT scans (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) are eliminated by cine CT and manual coregistration of attenuation-emission data to achieve proper coregistration (10,11). With systematically correct attenuation-emission coregistration, cardiac PET is suitable for assessing the severity of coronary artery disease (CAD) as the basis of invasive procedures, for stratifying risk, for following progression or regression of CAD after intense risk factor treatment, and for predicting coronary events in relation to the intensity of medical treatment (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26).…”

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confidence: 99%

Reducing Radiation Dose in Rest–Stress Cardiac PET/CT by Single Poststress Cine CT for Attenuation Correction: Quantitative Validation

et al. 2008

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Cardiac PET/CT is optimized by cine CT with dedicated shift software for manual correction of attenuation-emission misregistration. Separate rest and stress CT scans incur greater radiation dose to patients than does standard helical PET/CT or ''pure'' PET using rotating rod attenuation sources. To reduce radiation dose, we tested quantitative accuracy of using a single poststress cine CT attenuation scan for reconstructing rest perfusion images to eliminate resting CT attenuation scans. Methods: A total of 250 consecutive patients underwent diagnostic rest-dipyridamole myocardial perfusion PET/CT with 82 Rb and a 16-slice PET/CT scanner using averaged cine CT attenuation data during breathing at rest and stress. After correcting for any attenuation-emission misregistration, we quantitatively compared resting perfusion images reconstructed using rest cine CT attenuation data with the same resting emission data reconstructed with poststress cine CT attenuation data. Automated software quantifying average regional quadrant activity, severity, size, and combined size and severity of perfusion defects was used for this comparison. Results: Resting perfusion images reconstructed using rest cine CT attenuation data were quantitatively comparable to resting images reconstructed with poststress cine CT attenuation data with no clinically significant differences. Twenty-five (10%) of 250 cases required shifting of stress cine CT attenuation data to achieve optimal attenuationemission coregistration with resting perfusion data. Eliminating rest CT attenuation scans reduced CT radiation dose by 50% below rest-plus-stress cine CT protocols. Conclusion: Resting perfusion images reconstructed using poststress cine CT attenuation data are quantitatively comparable to resting images reconstructed with resting cine CT attenuation data. Eliminating the rest CT scan reduces CT radiation dose by 50%. Cardi ac PET is the most accurate noninvasive technology for assessing myocardial perfusion. Frequent misregistration artifacts in standard cardiac PET/CT using helical CT scans (1-11) are eliminated by cine CT and manual coregistration of attenuation-emission data to achieve proper coregistration (10,11). With systematically correct attenuation-emission coregistration, cardiac PET is suitable for assessing the severity of coronary artery disease (CAD) as the basis of invasive procedures, for stratifying risk, for following progression or regression of CAD after intense risk factor treatment, and for predicting coronary events in relation to the intensity of medical treatment (12-26). Mild reductions in relative coronary flow reserve by PET indicate early nonobstructive or diffuse CAD as the basis for treatment before significant stenosis develops (13,20,21).However, radiation dose to patients undergoing CT has become an important issue (27-30). Current standard PET/ CT protocols acquire separate rest and poststress CT scans for attenuation data to reconstruct rest and stress emission images. Cardiac PET/CT involves substantially great...

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“…However, in that study, the images were acquired by different scanners, and the differences between corresponding segments have not been directly compared. CT-based AC for cardiac imaging has also been compared with transmission techniques in phantoms (16) and in human subjects in a small pilot group (n 5 7) on separate scanners, in which significant differences have been observed (17).…”

Section: Discussionmentioning

confidence: 99%

Comparison of Myocardial Perfusion ⁸²Rb PET Performed with CT- and Transmission CT–Based Attenuation Correction

Slomka¹,

Meunier²,

Hayes³

et al. 2008

J Nucl Med

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CT-based attenuation correction (AC) for myocardial perfusion PET studies is challenging because of respiratory motion. Our study aimed to compare the transmission CT (TCT)-based and CT-based AC for myocardial perfusion PET/CT images with a direct semiquantitative approach comparing differences in segmental count distribution. Methods: Stress and rest 82 Rb PET scans from 54 consecutive patients acquired on a PET/CT scanner with dual CTbased and TCT-based AC were considered. TCT-and CT-based AC images were automatically registered to each other, and direct voxel-based and American Heart Association segment-based estimation of positive and negative changes between these scans was performed. Additionally, visual quality control (QC) of CT map alignment with PET emission data was performed by 2 expert observers, and studies with significant ($5 mm) misalignment were reprocessed with corrected CT alignment. Results: We used the 17-segment American Heart Association model for TCT-to-CT regional change analysis in all patients and found that 4 segments on rest and 4 segments on stress scans differed more than 3% between CT-and TCT-corrected images for studies without significant misalignments (,5 mm); only 1 differed by more than 5%. In cases with significant misalignment of greater than or equal to 3% TCT-CT AC, changes were observed on 14 rest and 10 stress segments; after alignment, these differences were still seen in 13 rest segments and 11 stress segments. Visual QC revealed that 46% of rest and 54% of stress PET scans were misaligned by greater than or equal to 5 mm with the CT maps acquired during normal breathing. The range of the reported PET/CT misalignment was 0-15 mm in x, 0-16 mm in y, and 0-20 mm in z directions. The overall agreement in visual QC of PET/CT alignment between the observers was 72.2% Conclusion: There are significant differences between TCT and CT AC applied to cardiac PET/CT studies, which remain after alignment of CT maps to emission data. Myocardi al perfusion PET is an established cardiac modality that is regarded as more accurate than SPECT in the diagnosis of coronary artery disease (CAD) (1). A key strength of PET, compared with SPECT, that is reflected in better diagnostic performance is the availability of accurate attenuation correction (AC), which has been traditionally performed with transmission sources. However, with the evolution of PET/CT in the oncologic arena (2), most PET scanners are currently sold in the hybrid PET/CT configuration, in which the CT-based AC has replaced the traditional transmission CT (TCT)-based AC technique. A low-dose CT-based AC has been proposed instead of the TCT-based approach for PET (3). None of the PET/CT systems offered today allows for TCT-based AC.CT-based AC for PET studies has proven challenging because of the effects of possible respiratory motion in general (4) and for myocardial perfusion studies more specifically (5,6). To date, regional perfusion differences between TCT-and CT-based AC have not been directly compared for the same m...

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PET/CT imaging: Effect of respiratory motion on apparent myocardial uptake

Cited by 86 publications

References 12 publications

Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Reducing Radiation Dose in Rest–Stress Cardiac PET/CT by Single Poststress Cine CT for Attenuation Correction: Quantitative Validation

Comparison of Myocardial Perfusion ⁸²Rb PET Performed with CT- and Transmission CT–Based Attenuation Correction

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PET/CT imaging: Effect of respiratory motion on apparent myocardial uptake

Cited by 86 publications

References 12 publications

Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Respiration-Averaged CT for Attenuation Correction in Canine Cardiac PET/CT

Reducing Radiation Dose in Rest–Stress Cardiac PET/CT by Single Poststress Cine CT for Attenuation Correction: Quantitative Validation

Comparison of Myocardial Perfusion 82Rb PET Performed with CT- and Transmission CT–Based Attenuation Correction

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Comparison of Myocardial Perfusion ⁸²Rb PET Performed with CT- and Transmission CT–Based Attenuation Correction