Quantification with a dedicated breast PET/CT scanner

Abstract

Purpose: Dedicated breast PET/CT is expected to have utility in local staging, surgical planning, monitoring of therapy response, and detection of residual disease for breast cancer. Quantitative metrics will be integral to several such applications. The authors present a validation of fully 3D data correction schemes for a custom built dedicated breast PET/CT (DbPET/CT) scanner via 18 F-FDG phantom scans. Methods: A component-based normalization was implemented, live-time was estimated with a multicomponent model, and a variance reduced randoms estimate was computed from delayed coincidences. Attenuation factors were calculated by using a CT based segmentation scheme while scatter was computed using a Monte Carlo (MC) simulation method. As no performance standard currently exists for breast PET systems, custom performance tests were created based on prior patient imaging results. Count-rate linearity for live-time and randoms corrections was measured with a decay experiment for a solid polyethylene cylinder phantom with an offset line source. A MC simulation was used to validate attenuation correction, a multicompartment phantom with asymmetric activity distribution provided an assessment of scatter correction, and image uniformity after geometric and detector normalization was measured from a high count scan of a uniform cylinder phantom. Raw data were reconstructed with filtered back projection (FBP) after Fourier rebinning. To quantify performance absolute activity concentrations, contrast recovery coefficients and image uniformity were calculated through region of interest analysis. Results: The most significant source of error was attributed to mispositioning of events due to pileup, presenting in count-related axial and transaxial nonuniformities that were not corrected for with the normalization method used here. Within the range of singles counts observed during clinical trials residual error after applying all corrections was comparable to that of a commercial whole body PET/CT system. Conclusions: The results suggest that DbPET/CT is capable of producing quantitative images under the operating conditions expected during patient imaging. V C 2012 American Association of Physicists in Medicine. [http://dx

High-resolution18F-FDG PET/CT for assessing disease activity in rheumatoid and psoriatic arthritis: findings of a prospective pilot study

“…CT images were reconstructed (Feldkamp method) in Hounsfield units with a voxel size of 0.38 3 0.38 3 0.28 mm 3 , 22 while the PET images were reconstructed (maximum a posterori method) with a voxel size of 1.1 3 1.1 3 3.3 mm 3 . PET image corrections were applied with the assistance of the co-registered CT 16 and images quantified in standardized uptake units were produced. Eligible patients (N 5 3) were transported to the MRI facility after PET/CT scanning.…”

“…14 A high-resolution extremity PET/CT scanner adaptable to wrist and hand imaging was built, 15 and its characterization in conditions typical for patient imaging was reported. 15,16 This system fully produces tomographic images with a spatial resolution of approximately 2.5 mm for the PET component and approximately 0.3 mm for the CT component. We report-employing prospective imaging data in human patients with established RA and PsA-the ability of this high-resolution PET/CT system to characterize and quantify disease activity and pathology associated with the two arthritides in the wrist and hand.…”

Simulation study of quantitative precision of the PET/X dedicated breast PET scanner

“…A number of dedicated breast PET projects are currently active, using either flat-panel detectors [13][14][15] or a partial/full ring geometry. [16][17][18][19][20] Integration with anatomical imaging has also been a theme. 13,16,17,21 We are currently building the PET/X scanner, which is a breast PET scanner combined with an x-ray mammography system.…”

Breast-Dedicated Radionuclide Imaging Systems

“…BD PET systems should have high spatialresolution uniformity (DOI and full-tomographic sampling) and accurate attenuation correction algorithms, to perform quantitative analysis on tumor uptake. Attenuation correction in the MAMMI BD PET system is performed using PET image segmentation (2), whereas the University of California, Davis, BD PET/CT system uses CT image segmentation (35). The MAMMI BD PET system is able to accurately quantify breast tumor SUV when compared with conventional PET/CT (36) and can examine intratumor structures and heterogeneity (9).…”

“…BD PET systems have great potential in breast cancer treatment planning and evaluation, through quantitatively evaluating the SUV of breast lesions during treatment (35) and through using high spatial resolution to look at intratumor structures and heterogeneity, which can aid in more accurate biopsy sampling of areas with the highest 18 F-FDG uptake (36). BD PET systems should have high spatialresolution uniformity (DOI and full-tomographic sampling) and accurate attenuation correction algorithms, to perform quantitative analysis on tumor uptake.…”