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This paper demonstrates a super-resolution method for improving the resolution in clinical positron emission tomography (PET) scanners. Super-resolution images were obtained by combining four data sets with spatial shifts between consecutive acquisitions and applying an iterative algorithm. Super-resolution attenuation corrected PET scans of a phantom were obtained using the two-dimensional and three-dimensional (3-D) acquisition modes of a clinical PET/computed tomography (CT) scanner (Discovery LS, GEMS). In a patient study, following a standard /sup 18/F-FDG PET/CT scan, a super-resolution scan around one small lesion was performed using axial shifts without increasing the patient radiation exposure. In the phantom study, smaller features (3 mm) could be resolved axially with the super-resolution method than without (6 mm). The super-resolution images had better resolution than the original images and provided higher contrast ratios in coronal images and in 3-D acquisition transaxial images. The coronal super-resolution images had superior resolution and contrast ratios compared to images reconstructed by merely interleaving the data to the proper axial location. In the patient study, super-resolution reconstructions displayed a more localized /sup 18/F-FDG uptake. A new approach for improving the resolution of PET images using a super-resolution method has been developed and experimentally confirmed, employing a clinical scanner. The improvement in axial resolution requires no changes in hardware.

Background Studies in anesthetized dogs have shown that myocardial fibers shorten ≈8%. However, in the endocardium, shortening occurs to a much greater extent at 90° to the fiber orientation (“cross-fiber shortening”) than it does along the fiber direction. The purpose of this study was to estimate the extent of fiber and cross-fiber shortening in the normal human left ventricle and in patients with idiopathic dilated cardiomyopathy (IDC). Methods and Results Ten normal subjects and nine patients with IDC were imaged with magnetic resonance tissue tagging. Finite strain analysis was used to calculate endocardial and epicardial shortening in the fiber and cross-fiber directions using anatomic fiber angles from representative autopsy specimens as references. Anatomic fiber angles were not different between normal subjects and IDC patients. Epicardial fiber strain was −0.14±0.01 in normal subjects and −0.08±0.01 in IDC patients ( P <.0001 versus normal subjects). Epicardial cross-fiber strain was −0.08±0.01 in normal subjects and −0.06±0.01 in IDC patients ( P =NS). Endocardial fiber strain was −0.16±0.01 in normal subjects and −0.09±0.01 in IDC patients ( P <.0001), and endocardial cross-fiber strain was −0.26±0.01 in normal subjects and −0.15±0.01 in IDC patients ( P <.0001). Cross-fiber shortening was greater than fiber shortening at the endocardium in both normal subjects ( P <.0001) and IDC patients ( P <.05). Conclusions In normal humans, the direction of maximal deformation aligns with the fiber direction in the epicardium but is perpendicular to the fiber direction in the endocardium. When strain in a coordinate system aligned to the fibers is estimated, cross-fiber shortening is found to be the dominant shortening strain at the endocardium. Normal fiber shortening is ≈15%, and this is markedly reduced in IDC. The normal transition in fiber orientation through the wall is not altered in IDC, and cross-fiber shortening is still the dominant strain at the endocardium, suggesting that interactions between myocardial layers persist in these patients.

We show an iterative reconstruction framework for diffraction ultrasound tomography. The use of broad-band illumination allows significant reduction of the number of projections compared to straight ray tomography. The proposed algorithm makes use of forward nonuniform fast Fourier transform (NUFFT) for iterative Fourier inversion. Incorporation of total variation regularization allows the reduction of noise and Gibbs phenomena while preserving the edges. The complexity of the NUFFT-based reconstruction is comparable to the frequency-domain interpolation (gridding) algorithm, whereas the reconstruction accuracy (in sense of the L/sup 2/ and the L/sup /spl infin// norm) is better.

Cancer stem cells, also termed tumor initiating cells (TICs), are a rare population of cells within the tumor mass which initiate tumor growth and metastasis. In pancreatic cancer, TICs significantly contribute to tumor re-growth after therapy, due to their intrinsic resistance. Here we demonstrate that copper oxide nanoparticles (CuO-NPs) are cytotoxic against TIC-enriched PANC1 human pancreatic cancer cell cultures. Specifically, treatment with CuO-NPs decreases cell viability and increases apoptosis in TIC-enriched PANC1 cultures to a greater extent than in standard PANC1 cultures. These effects are associated with increased reactive oxygen species (ROS) levels, and reduced mitochondrial membrane potential. Furthermore, we demonstrate that CuO-NPs inhibit tumor growth in a pancreatic tumor model in mice. Tumors from mice treated with CuO-NPs contain a significantly higher number of apoptotic TICs in comparison to tumors from untreated mice, confirming that CuO-NPs target TICs in vivo. Overall, our findings highlight the potential of using CuO-NPs as a new therapeutic modality for pancreatic cancer.

Several studies have described nonuniform blurring of myocardial perfusion imaging (MPI) due to respiration. This article describes a technique for correcting the respiration effect and assesses its effectiveness in clinical studies. Methods: Simulated phantoms, physical phantoms, and patient scans were used in this study. A heart phantom, which oscillated back and forth, was used to simulate respiration. The motion was measured on a γ-camera supporting list-mode functionality synchronized with an external respiratory strap or resistor sensor. Eight clinical scans were performed using a 1-d ^99mTc-sestamibi protocol while recording the respiratory signal. The list-mode capability along with the strap or sensor signals was used to generate respiratory bin projection sets. A segmentation process was used to detect the shift between the respiratory bins. This shift was further projected to the acquired projection images for correction of the respiratory motion. The process was applied to the phantom and patient studies, and the rate of success of the correction was assessed using the conventional bull's eye maps. Results: The algorithm provided a good correction for the phantom studies. The shift after the correction, measured by a fitted ellipsoid, was <1 mm in the axial direction. The average motion due to respiration in the clinical studies was 9.1 mm in the axial direction. The average shift between the respiratory phases was reduced to 0.5 mm after correction. The maximal change in the bull's eye map for the clinical scans after the correction was 6%, with a mean of 3.75%. The postcorrection clinical summed perfusion images were more uniform, consistent, and, for some patients, clinically significant when compared with the images before correction for respiration. Conclusion: Myocardial motion generated by respiration during MPI SPECT affects perfusion image quality and accuracy. Motion introduced by respiration can be corrected using the proposed method. The degree of correction depends on the patient respiratory pattern and can be of clinical significance in certain cases.