Current state of hybrid imaging: attenuation correction and fusion

Nye, Jonathon A.; Faber, Tracy L.

doi:10.1007/s12350-011-9380-1

Cited by 6 publications

(2 citation statements)

References 63 publications

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“…The emission‐driven method is less technically difficult to implement compared to other deformable algorithms and groups have applied nonlinear warping algorithms to solve the PET/CT registration problem, (14) though none have been extensively validated for cardiac perfusion imaging. The importance of accurate data correction in cardiac PET/CT not only affects interpretation of perfusion images but also more advanced analysis techniques, such as the calculation of absolute blood flow (15) .…”

Section: Discussionmentioning

confidence: 99%

Quantitative outcome of registration methods for correcting cardiac drift in cardiac PET/CT imaging

Nye

Tudorascu

Esteves

et al. 2016

J Applied Clin Med Phys

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Myocardial perfusion studies suffer from artifacts caused by misalignment of the transmission and emission data due to the influences of voluntary and involuntary patient motion. Regardless of normalG68e or respiratory‐averaged CT based attenuation correction and good patient cooperation, approximately 21% of perfusion studies exhibit artifacts arising from misalignment that cannot be corrected by manipulating the attenuation acquisition protocol. This misalignment, termed cardiac drift, is caused by slow‐moving abdominal cavity contents that reposition the heart in the thorax and appear as myocardial uptake overlying the left CT lung in fused PET/CT images. This study evaluates three postimaging registration techniques to correct PET/CT misalignment by altering the transmission map to match myocardial uptake. Simulated misalignment studies were performed with a cardiac torso phantom filled with [normalF18]FDG at 10:1 myocardium/background. An air‐filled saline bag affixed to the medial left lung surface served as a distensible lung. An initial CT acquisition was followed by successive PET acquisitions consisting of small displacements of the cardiac insert into the left lung. Phantom transmission scans were aligned to the myocardial uptake in the emission scans by applying 1) full rigid‐body translations and rotations, 2) rigid‐body restricted to medial / lateral and superior / inferior translation, or 3) an emission‐driven method that adds myocardial tissue to the transmission scan. These methods were also applied to 10 low‐likelihood coronary artery disease (CAD) patients showing signs of cardiac drift. Full rigid‐body registration showed significant over‐correction (p<0.004) of activity concentrations in the artifact areas of the phantom data due the relocation of highly attenuating structures (i.e., spine). Inaccurate regional activity distributions were also observed as streaks extending from the spine and these results were replicated in the patient population. There was no significant difference between the true phantom activity concentration after correction with the emission‐driven method. Misalignment corrected with the rigid‐body registration results in an increase in activity concentration but fails to accurately recover the true concentration. These data suggest that a nonlinear image registration approach such as an emission‐driven method results in a more uniform activity distribution throughout the myocardium, and is more appropriate for addressing the cardiac drift misalignment problem.PACS number(s): 87.57.uk, 87.57.Q, 87.57.nj, 87.57.C, 87.19.Hh

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Section: Discussionmentioning

confidence: 99%

Quantitative outcome of registration methods for correcting cardiac drift in cardiac PET/CT imaging

Nye

Tudorascu

Esteves

et al. 2016

J Applied Clin Med Phys

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“…Both SPECT and PET can be combined with computed tomography (CT) scanners permitting multimodality hybrid and fusion imaging [ 47 ]. CT can be employed for attenuation correction of SPECT images in such hybrid scanners.…”

Section: Spect and Computed Tomography Angiography Hybrid Imagingmentioning

confidence: 99%

Myocardial Perfusion Imaging Utilizing Single Photon Emission Computed Tomography Techniques

Beller

2015

Coronary Artery Disease

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The major clinical applications of single photon computed tomography (SPECT) myocardial perfusion imaging (MPI) include detection of CAD among patients presenting with symptoms such as chest pain or dyspnea, assessing prognosis in patients with suspected or known CAD, identifying which CAD patients may benefi t most from coronary revascularization rather than medical therapy and determining extent of myocardial viability in patients with ischemic cardiomyopathy. Patients with normal SPECT MPI studies have an excellent prognosis with <1 % annual rate of cardiac death or nonfatal myocardial infarction (MI). The annual event rate increases to 6 % in those patients with abnormal scans. Compared to nondiabetic patients, patients with diabetes with abnormal SPECT scans have a higher event rate with female diabetic patients with abnormal scans having a >10 % annual cardiac death or MI rate. Gated SPECT imaging permits the assessment of regional wall motion and measurement of the LV ejection fraction, which adds further prognostic information to the perfusion fi ndings. Stress-only SPECT imaging in low risk patients eliminates the need for rest imaging when the stress scans are normal. This reduces radiation exposure to the patient as well as reduces cost. Vasodilator SPECT imaging is currently most frequently performed in patients unable to exercise adequately using regadenoson, a specifi c adenosine A2a receptor agonist. SPECT MPI can be combined with CT coronary angiography (CTA) for hybrid multimodality imaging of anatomy and physiology. CTA is most often performed when the SPECT images are non-diagnostic or equivocal. Conversely, if the CTA is done fi rst, SPECT imaging may be useful as the second test in the instance of fi nding intermediate coronary stenosis (50-70 % narrowing) on CTA. Resting SPECT imaging with either thallium-201 or one of the Tc-99m-labeled perfusion agents (sestambi or tetrofosmin) can be used to determine the extent of viability in dysfunction myocardial segments. The greater the extent of viability in dyssynergic segments, the greater the chance of improved regional and global function after revascularization. Finally, new solid state gamma cameras employing cadmium-zinc-telluride (CZT) crystals with new software algorithms have emerged in recent years. This new technology permits more rapid acquisition of SPECT images at a lower radiation dose to the patient.

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