Completed

The Effects of Respiratory Motion on CT Based Attenuation Correction of Positron Emission Tomography Data: Liver and Heart Studies

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What is being collected

Data Collection

Who is being recruted

Over 7 Years
See all eligibility criteria
How is the trial designed

Observational
Study Start: July 2004
See protocol details

Summary

Principal SponsorNational Institutes of Health Clinical Center (CC)
Last updated: January 14, 2026
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Study start date: July 1, 2004

Actual date on which the first participant was enrolled.

Current clinical FDG imaging with the NIH's PET/CT machine (and in fact with most commercial PET/CT machines) requires a CT scan be acquired prior to the PET scan. This CT scan is used for attenuation correction of the PET data and to permit fusion of anatomical and metabolic image data. One difficulty with use of the CT scan for attenuation correction ('CTAC') is that the CT scan is rapid compared to the breathing cycle. Each CT slice captures the lungs at one (usually arbitrary) phase of the respiratory cycle. The PET data on the other hand take many minutes to acquire, and so average the motion effects of the entire respiratory cycle together. This 'freezing' of the respiratory cycle by the CT, and blurring of the respiratory cycle during PET produces a mis-match between the PET and CT data. This mis-match can produce improper attenuation correction during PET reconstruction, especially at soft tissue/lung interfaces. The existence of this phenomenon has been reported in the literature \[1-7\], especially at the dome of the liver, but it has not been thoroughly quantified. Little or no data is available to indicate the quantitative errors the effect produces in cardiac imaging\[8\]. This despite the fact that the myocardium is only about 10mm thick, and it has been reported that the heart moves on average 9mm (and as much as 14mm) during a single average respiratory cycle\[9\]. The purpose of this protocol is to determine the degree to which respiratory motion may influence quantitative PET imaging, especially at the lung/liver interface and free wall of myocardium. By characterizing the magnitude of the effect, we hope to gain knowledge about when correction for the effect is and is not necessary. It is hoped that the information gained will also allow us to suggest potential methods to perform such corrections. To gain the above information we will modify the CT acquisition protocol for subjects already scheduled to undergo a whole body FDG PET/CT scan. In summary, rather than acquiring the usual single full radiation exposure CT (taking approx 20-30 seconds), we will acquire 3 CT scans (each taking approximately 20-30 seconds), each at 1/3 the usual radiation exposure. Each CT will be acquired at a different phase of the respiratory cycle (as opposed to current acquisition, which is only at end-expiration). The subsequent PET data will be acquired as usual, but will be processed and analyzed separately with each of the CT scans and also with a summed CT scan. Note that subjects agreeing to participate in this protocol will receive no additional radiation exposure. Participation in the protocol will extend the current overall scan time (typically greater than 45 minutes) a very small amount (about 40-60 additional seconds for imaging, and about 60 additional seconds for patient set up, etc).

Official TitleThe Effects of Respiratory Motion on CT Based Attenuation Correction of Positron Emission Tomography Data: Liver and Heart Studies 
NCT00088361
Principal SponsorNational Institutes of Health Clinical Center (CC)
Last updated: January 14, 2026
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.
Design Details

30 patients to be enrolled

Total number of participants that the clinical trial aims to recruit.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Criteria

Any sex

Biological sex of participants that are eligible to enroll.

Over 7 Years

Range of ages for which participants are eligible to join.

Healthy volunteers not allowed

If individuals who are healthy and do not have the condition being studied can participate.

Criteria

* INCLUSION CRITERIA Up to 30 subjects will take part in the study, chosen from sequential incoming clinical patients who are scheduled for PET/CT studies of the torso and who have had or will have a diagnostic CT within one week of the PET/CT study, without regard to disease. The number of subjects selected for study per week will depend on patient load and availability of scanner and technologist). Approximately an equal number of males and females will be selected by alternating each selection between male and female. The selection of subjects asked to participate will be random, in the sense that whenever technologist and analysis time is available, the next subject scheduled for a whole body scan will be asked to participate. EXCLUSION CRITERIA The only exclusion criteria will be subjects with respiratory difficulties. Children under the age of 12.

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.

This study has 1 location

Suspended

National Institutes of Health Clinical Center (CC)

Bethesda, United StatesSee the location
CompletedOne Study Center