Automated 3D elastic registration for improving tumor localization in whole-body PET-CT from combined scanner.

Combined PET/CT scanners provide the ability to produce matching metabolic (from PET) and anatomic (from CT) information in a single examination. However, misalignments continue to exist in tumor localization in PET and CT images acquired using these scanners, due to their inability to compensate for nonrigid misalignment resulting from patient breathing and involuntary movement. We demonstrate that our automatic image subdivision-based elastic registration algorithm can correct this misalignment. In a quantitative validation involving 13 expert-identified tumor nodules in six PET-CT image pairs, the algorithm demonstrated statistically significant improvement over the scanner-defined localization. The accuracy of algorithm-determined localization was evaluated to be comparable to average manually defined localization. The results indicate the potential of using our registration algorithm for applications like radiotherapy treatment planning and treatment-monitoring involving combined PET/CT scanners.

Developments in nuclear cardiology: transition from single photon emission computed tomography to positron emission tomography-computed tomography.

Recent advances in positron emission tomography (PET) instrumentation have paralleled those of multichannel computed tomography (CT) for cardiac applications. Whereas multichannel CT angiography provides information on the presence and extent of anatomical luminal narrowing of epicardial coronary arteries, stress myocardial perfusion PET provides information on the downstream functional consequences of such anatomic lesions. With the advent of hybrid PET/CT systems, such complementary information of anatomy and physiology can be realized immediately at the same imaging session. By acquiring dynamic, gated myocardial perfusion data, PET studies provide insight into impairment of regional coronary blood flow reserve and microvascular endothelial dysfunction. This paper presents recent developments in PET detector materials, acquisition modes, combined PET/CT scanners, rubidium-82 (Rb-82) gated myocardial perfusion studies and analysis methods for absolute myocardial blood flow quantification.

Tumor localization and image registration of F-18 FDG coincidence detection scans with computed tomographic scans.

PURPOSE: The aim of this study was to determine the feasibility of registering routine clinical F-18 fluorodeoxyglucose (FDG) coincidence detection (CD) scans with computed tomographic (CT) scans for radiation treatment planning and case management. METHODS: F-18 FDG CD and chest CT scans, performed in 10 randomly selected patients with confirmed or possible adenocarcinoma of the lung, were evaluated. The quality of the matches was verified by comparisons of the center-to-center distance between a region of interest (ROI) manually drawn on the CT slice and warped onto the CD slice with an ROI drawn manually directly on the CD slice. In addition, the overlap between the two ROIs was calculated. RESULTS: All 10 F-18 FDG CD and CT scans were registered with good superimposition of soft tissue density on increased radionuclide activity. The center-to-center distance between the ROIs ranged from 0.29 mm to 8.08 mm, with an average center-to-center distance of 3.89 mm +/- 2.42 mm (0.69 pixels +/- 0.34 pixels). The ROI overlap ranged from 77% to 99%, with an average of 90% +/- 5.6%. CONCLUSIONS: Although the use of F-18 FDG CD shows great promise for the identification of tumors, it shares the same drawbacks as those associated with radiolabeled monoclonal antibody SPECT and ligand-based positron emission tomographic scans in that anatomic markers are limited. This study shows that image registration is feasible and may improve the clinical relevance of CD images.