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

doi:10.1016/j.nuclcard.2006.09.003

Journal of Nuclear Cardiology

Volume 13, Issue 6, November 2006, Pages 821-830

https://doi.org/10.1016/j.nuclcard.2006.09.003 Get rights and content

Background

Positron emission tomography (PET) attenuation correction (AC) using computed tomography (CT) can be affected by respiratory motion: hi-speed CT captures 1 point of the respiratory cycle while PET emission data averages many cycles. We quantified the changes in apparent myocardial uptake due to this respiratory-induced CT attenuation mismatch.

Methods

Twenty-two patients undergoing fluorine-18 fluorodexyglucose (FDG) PET/CT received 3 sequential CT scans at normal resting end-inspiration (CT_INSPIR), ending expiration (CT_EXPIR), and at midvolume between end-expiration and end-inspiration (CT_MIDVOL). A pneumotachometer measured absolute changes in lung volume. Seven subjects also underwent a 3-minute transmission scan with a ⁶⁸Ge rotating rod source (RRS). The PET emission data set was reconstructed up to 4 times using CT_EXPIR, CT_INSPIR, CT_MIDVOL, and RRS AC maps. Relative heart position and cardiac uptake was measured for each CT attenuation correction.

Results

Respiratory motion produced marked changes in global and regional myocardial uptake. Changes were large in the lateral and anterior regions at the lung-soft tissue interface (up to 30% using CT_INSPIR compared to CT_EXPIR for AC) and smaller in the septal region (10% or less). Data corrected with CT_EXPIR agreed best with the RRS.

Conclusion

Respiratory effects can introduce large inhomogeneities in apparent myocardial uptake when CT is used for attenuation correction.

Section snippets

Study Population

The study group consisted of 22 subjects (10 women and 12 men; mean age, 43.6 ± 15.1 years; mean height, 172.8 ± 8.3 cm; mean weight, 79.1 ± 21.1 kg). The study was performed under a National Institutes of Health–approved protocol. Twenty-five subjects originally entered the protocol, but one was excluded because of scanner malfunction, one because of inadvertent patient motion, and one because of error in following breathing instructions. All patients gave written informed consent. All were

Heart Motion

Consistent with previous reports,¹⁴ the heart (and other organs, such as the liver) was displaced between the 3 CT scans. Figure 2 shows a typical coronal view of the same CT slice of a patient. These 2 CT scans were taken during normal breathing at end-expiration and at end-inspiration (mean change in lung volume compared with end-expiration, averaged over all subjects, was 0.52 ± 0.25 L at midvolume and 1.01 ± 0.54 L at end-inspiration). By use of CT_EXPIR as a reference, the mean motion of

Discussion

Whether the patient holds or does not hold his or her breath during the CT scan, a fast CT scan freezes the lungs at one point in the respiratory cycle. Because this CT scan does not duplicate the respiratory blurring inherent in the emission data, using the CT scan to perform AC may substantially alter the apparent cardiac FDG uptake. The decrease in the global apparent uptake (ie, averaged over the whole myocardium) when CT_MIDVOL or CT_INSPIR was used for AC rather than CT_EXPIR is probably due

Acknowledgment

The authors have indicated they have no financial conflicts of interest.

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

Background

Methods

Results

Conclusion

Section snippets

Study Population

Heart Motion

Discussion

Acknowledgment

Mol Imaging Biol

Acad Radiol

Dual-modality PET/CT imaging: the effect of respiratory motion on combined image quality in clinical oncology

Eur J Nucl Med Mol Imaging

Respiration-induced attenuation artifact at PET/CT: technical considerations

Radiology

PET-CT image co-registration in the thorax: influence of respiration

Eur J Nucl Med Mol Imaging

Respiratory motion artifacts on PET emission images obtained using CT attenuation correction on PET-CT

Eur J Nucl Med Mol Imaging

The CT motion quantitation of lung lesions and its impact on PET-measured SUVs

J Nucl Med

PET/CT: artifacts caused by bowel motion

Nucl Med Commun

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