OBJECTIVE: Recently 99mTc-glucarate, a radiolabeled glucose analogue, has been considered as a SPECT alternative to 18F-FDG and PET for non-invasive detection of certain tumors. Thus far there have been few studies on (99m) Tcglucarate for tumor imaging and fewer, if any, studies comparing (99m)Tc-glucarate with 18F-FDG. As a preliminary indication of the properties of (99m)Tc-glucarate as a possible substitute for 18F-FDG in animal studies, we have imaged mice bearing xenografts of four tumor types with (99m)Tc-glucarate and have compared in two mice with one of these tumor types the 99mTc and 18F biodistributions. METHODS: Two mice bearing SUM190 breast cancer xenografts received 1 mCi of (99m)Tc-glucarate and were imaged on a NanoSPECT/CT small animal camera. One day later, the same animals received 1 mCi of 18F-FDG and were imaged on a MosaicHP PET small animal camera. In addition, 0.5-1 mCi of (99m)Tc-glucarate only was administered to mice bearing xenografts induced by BxPC3 pancreatic cancer cells, HEK-293 renal cell carcinomas cells or HCT-116 colorectal tumor cells. NanoSPECT/CT acquisitions were performed in these mice to evaluate tumor accumulations. RESULTS: In the SUM190 xenografted mice, the average tumor accumulation was 1.4 % (ID%/cm3) for (99m)Tc-glucarate and 2.1 % (ID%/cm3) for 18F-FDG. While slightly higher than (99m)Tc-glucarate, the tumor accumulation of 18F-FDG was accompanied by higher bone marrow and muscle accumulations at levels that could interfere with the tumor image depending upon location. The whole body clearance of (99m)Tc-glucarate was faster than that of 18F-FDG. Tumor accumulation of (99m)Tc-glucarate varied among tumor types but the tumors were readily visible in all images. CONCLUSION: In a direct comparison in the same two SUM190 tumored animals, SPECT images obtained with (99m)Tcglucarate compared favorably with PET images obtained with 18F-FDG. Tumor images with 99mTc-glucarate were also positive in three additional tumor mouse models. While further comparison studies are necessary, we conclude that (99m)Tcglucarate may be a more convenient and less expensive alternative to 18F-FDG for tumored mouse studies.

PURPOSE: The aim of this study is to determine using MRI in volunteers whether the rigid-body-motion (RBM) model can be approximately used to estimate the gross body-motion of the heart from that of external markers on patient's chest. Our target clinical application is to use a visual-tracking-system (VTS) which employs stereoimaging to estimate heart motion during SPECT/CT and PETCT myocardial perfusion imaging. METHODS: To investigate body-motion separate from the respiration the authors had the volunteers hold their breath during the acquisition of a sequence of two sets of EKG-triggered MRI sagittal slices. The first set was acquired pre-motion, and the second postmotion. The motion of the heart within each breath-hold set of slices was estimated by registration to the semiautomatic 3D segmentation of the heart region in a baseline set acquired using the Navigator technique. The motion of the heart between the pre- and postmotion sets was then determined as the difference in the individual motions in comparison to the Navigator sets. An analysis of the combined motion of the individual markers on the chest was used to obtain an estimate of the six-degree-of-freedom RBM from the VTS system. The metric for judging agreement between the motion estimated by MRI and the VTS was the average error. This was defined as the average of the magnitudes of the differences in the vector displacements of all voxels in the heart region. Studies with the Data Spectrum Anthropomorphic Phantom and "No-Motion" studies in which the volunteer did not intentionally move were used to establish a baseline for agreement. With volunteer studies a t-test was employed to determine when statistically significant differences in Average Errors occurred compared to the No-motion studies. RESULTS: For phantom acquisitions, the Average Error when the motion was just translation was 0.1 mm. With complex motions, which included a combination of rotations and translations, the Average Error increased to 3.6 mm. In the volunteers the Average Error averaged over all No-Motion acquisitions was 1.0 mm. For the case of translational motion, which might be expected to be RBM, the Average Error averaged over all volunteer studies increased to 2.6 mm, which was statistically different from the No-Motion studies. For the case of bends and twists of the torso, which would be expected to challenge the RBM model, the Average Error averaged over all such volunteer studies was 4.9 mm and was again statistically different. Investigations of motion of the arm including just bending at the elbow and leg motion resulted in Average Errors which were not statistically different from the No-Motion studies. However, when shoulder movement was included with arm motion the Average Error was near that of torso bends and twists, and statistically different. CONCLUSIONS: Use of the RBM model with VTS predictions of heart motion during reconstruction should decrease the extent of artifacts for the types of patient motion studied. The impact of correction would be less for torso bends and twists, and arm motion which includes the shoulders.