25 research outputs found
Computer analysis of cardiac radionuclide data
Gamma-camera tomography gives uniform in-plane and cross-plane resolution with propagation of the defect from one plane to another determined only by the usual camera-collimator resolution. These images may be reformatted by computer to portray slices in any orientation. Cross plane resolution is slightly worse than for the other methods, but it is uniform. The efficiency is less than either quadrant slant hole or seven pinhole apertures. Rotating cameras are not portable nor can they be used for dynamic studies.Both slant hole collimators and seven pinhole apertures distort the object in the depth dimension because of the limited viewing angle. The slant hole geometry provides somewhat better sampling and less plane-to-plane cross talk especially for the more distant planes. The full width half maximum of the depth response is not a sensitive indicator of this problem because the depth response function has very long tails.To date, best overall performance of the limited angle methods is offered by the 40[deg] slant hole collimator on a large field-of-view camera. This, however, is not a portable unit and has a field-of-view too small for about 10% of the patients.Seven pinhole imaging offers the advantage of having been well studied by a number of institution.87-90 A large pool of normal patient studies exists and the performance is well documented. Although the seven pinhole alone is suited to dynamic studies, any of the methods may be adapted to multigated studies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25165/1/0000603.pd
FDG-PET Interpreted By Deauville Criteria Prior to Allogeneic Transplantation Predicts Outcomes in Patients with Relapsed or Refractory Hodgkin Lymphoma
ACR guidance document on MR safe practices: 2013
Because there are many potential risks in the MR environment and reports of adverse incidents involving patients, equipment and personnel, the need for a guidance document on MR safe practices emerged. Initially published in 2002, the ACR MR Safe Practices Guidelines established de facto industry standards for safe and responsible practices in clinical and research MR environments. As the MR industry changes the document is reviewed, modified and updated. The most recent version will reflect these changes. J. Magn. Reson. Imaging 2013;37:501–530. © 2013 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96674/1/24011_ftp.pd
The appended curve technique for deconvolutional analysis —method and validation
Deconvolutional analysis (DCA) is useful in correction of organ time activity curves (response function) for variations in blood activity (input function). Despite enthusiastic reports of applications of DCA in renal and cardiac scintigraphy, routine use has awaited an easily implemented algorithm which is insensitive to statistical noise. The matrix method suffers from the propagation of errors in early data points through the entire curve. Curve fitting or constraint methods require prior knowledge of the expected form of the results. DCA by Fourier transforms (FT) is less influenced by single data points but often suffers from high frequency artifacts which result from the abrupt termination of data acquisition at a nonzero value.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46829/1/259_2004_Article_BF00254393.pd
Nuclear Magnetic Resonance: Current and Future Clinical Applications
Nuclear magnetic resonance has evolved from a laboratory analytical tool to become a rapidly developing discipline in clinical medicine. We present a brief historical overview, an introduction to the basic principles of the phenomenon, and a statement of the current status of clinical imaging. We have elected to use the traditional terminology nuclear magnetic resonance to refer to the imaging component of the field rather than the American College of Radiology (ACR) modification magnetic resonance. We do this out of respect for the founders of the field
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Automated in vivo Assessment of Vascular Response to Radiation using a Hybrid Theranostic X-ray Irradiator/Fluorescence Molecular Imaging System.
Hypofractionated stereotactic body radiotherapy treatments (SBRT) have demonstrated impressive results for the treatment of a variety of solid tumors. The role of tumor supporting vasculature damage in treatment outcome for SBRT has been intensely debated and studied. Fast, non-invasive, longitudinal assessments of tumor vasculature would allow for thorough investigations of vascular changes correlated with SBRT treatment response. In this paper, we present a novel theranostic system which incorporates a fluorescence molecular imager into a commercial, preclinical, microCT-guided, irradiator and was designed to quantify tumor vascular response (TVR) to targeted radiotherapy. This system overcomes the limitations of single-timepoint imaging modalities by longitudinally assessing spatiotemporal differences in intravenously-injected ICG kinetics in tumors before and after high-dose radiation. Changes in ICG kinetics were rapidly quantified by principle component (PC) analysis before and two days after 10 Gy targeted tumor irradiation. A classifier algorithm based on PC data clustering identified pixels with TVR. Results show that two days after treatment, a significant delay in ICG clearance as measured by exponential decay (40.5±16.1% P=0.0405 Paired t-test n=4) was observed. Changes in the mean normalized first and second PC feature pixel values (PC1 & PC2) were found (P=0.0559, 0.0432 paired t-test), suggesting PC based analysis accurately detects changes in ICG kinetics. The PC based classification algorithm yielded spatially-resolved TVR maps. Our first-of-its-kind theranostic system, allowing automated assessment of TVR to SBRT, will be used to better understand the role of tumor perfusion in metastasis and local control
Whole-Body Distribution of Leukemia and Functional Total Marrow Irradiation Based on FLT-PET and Dual-Energy CT
This report describes a multimodal whole-body 3′-deoxy-3′[(18)F]-fluorothymidine positron emission tomography (FLT-PET) and dual-energy computed tomography (DECT) method to identify leukemia distribution within the bone marrow environment (BME) and to develop disease- and/or BME-specific radiation strategies. A control participant and a newly diagnosed patient with acute myeloid leukemia prior to induction chemotherapy were scanned with FLT-PET and DECT. The red marrow (RM) and yellow marrow (YM) of the BME were segmented from DECT using a basis material decomposition method. Functional total marrow irradiation (fTMI) treatment planning simulations were performed combining FLT-PET and DECT imaging to differentially target irradiation to the leukemia niche and the rest of the skeleton. Leukemia colonized both RM and YM regions, adheres to the cortical bone in the spine, and has enhanced activity in the proximal/distal femur, suggesting a potential association of leukemia with the BME. The planning target volume was reduced significantly in fTMI compared with conventional TMI. The dose to active disease (standardized uptake value >4) was increased by 2-fold, while maintaining doses to critical organs similar to those in conventional TMI. In conclusion, a hybrid system of functional–anatomical–physiological imaging can identify the spatial distribution of leukemia and will be useful to both help understand the leukemia niche and develop targeted radiation strategies
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Safety Considerations of 7-T MRI in Clinical Practice
Although 7-T MRI has recently received approval for use in clinical patient care, there are distinct safety issues associated with this relatively high magnetic field. Forces on metallic implants and radiofrequency power deposition and heating are safety considerations at 7 T. Patient bioeffects such as vertigo, dizziness, false feelings of motion, nausea, nystagmus, magnetophosphenes, and electrogustatory effects are more common and potentially more pronounced at 7 T than at lower field strengths. Herein the authors review safety issues associated with 7-T MRI. The rationale for safety concerns at this field strength are discussed as well as potential approaches to mitigate risk to patients and health care professionals. (C) RSNA, 201