PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 7708837

Deconvolution of planar scintigrams by maximum entropy.

D E Simpson·J S Fleming·A J Aldous·G J Daniell
View original source ↗Export metadata ↓

Abstract

Planar scintigrams are deconvolved with a point spread function using the maximum entropy method with the aim of improving image quality. The technique requires the specification of several parameters. These are related to the level of noise present in the data and our a priori knowledge of the object imaged. The performance of the technique is tested for a wide range of these parameters using images of a Williams phantom in scattering material and a figure of merit, derived from the detectability of the smallest cold spot, is calculated. For close to optimal values of the parameters a factor of two improvement in the figure is found. A processed bone image shows improved contrast and resolution. Maximum entropy processing could be used to increase image quality or allow comparable image quality with reduced imaging time or patient dose.

Explore related subjects

Bone and BonesGamma RaysHumansMathematicsModels, TheoreticalProbabilityRadionuclide ImagingThermodynamicsJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

D E Simpson, J S Fleming, A J Aldous, G J Daniell. 1995. Deconvolution of planar scintigrams by maximum entropy.. https://doi.org/10.1088/0031-9155%2F40%2F1%2F013

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Cytogenetic and molecular cytogenetic findings in dedifferentiated liposarcoma with neural-like whorling pattern and metaplastic bone formation.

Dedifferentiated liposarcoma is a subtype of liposarcoma characterized by juxtaposition of well-differentiated liposarcoma with a nonadipocytic sarcoma. A peculiar form of dedifferentiated liposarcoma has been described, characterized by a nonlipogenic component with a neural-like whorling pattern of growth and metaplastic bone formation. We report the cytogenetic and molecular genetic findings of this peculiar form of dedifferentiation in a retroperitoneal tumor found in a 58-year-old female. The neoplasm had typical histologic findings and a complex karyotype characterized by several numeric and structural chromosomal abnormalities, including the presence of ring and giant rod chromosomes. Molecular cytogenetic studies found high levels of amplification of the MDM2 oncogene, consistent with the amplification of the 12q14 chromosome band, a cytogenetic abnormality commonly found in these tumors. These findings indicate that, despite its unique and peculiar morphologic features, this unusual type of dedifferentiated liposarcoma shares many of the cytogenetic features and molecular genetic abnormalities found in other forms of dedifferentiation. The specific cytogenetics and molecular determinants of these peculiar morphologic findings, however, remain unknown.

Bone and Bones↗
PubMed2007

Traditional and virtual microscopy compared experimentally in a classroom setting.

The technology known as virtual microscopy is now widely available to medical students. A number of medical school histology and pathology course directors, including those at the Eastern Virginia Medical School, are exploring the question of how best to make use of this new tool. The current study compared the efficacy of teaching and testing one unit of histology, bone and cartilage, using two technologies, namely, virtual microscopy and traditional microscopy. Additionally, the study examined whether low, moderate, high moderate, or high achieving students perform more effectively in any of the learning/testing formats. In a completely randomized block design, 96 first semester, first-year medical students were grouped by previous exam quartiles then subsequently randomly assigned to one of four groups. Using identical laboratory exercises with highly comparable slides for each experimental group, half of the subjects learned the exercise with traditional microscopy and half learned with virtual microscopy. Subjects were further randomly subdivided into virtual or actual testing groups. The authors found no significant differences in test scores when they examined effects by learning group or by testing group, nor were there significant interaction effects. Student performance evaluated by previous exam quartile was significant (P < 0.001). That is, students who had scored in a particular quartile on a previous test tended to score in the same quartile on the bone and cartilage test regardless of learning or testing method. In a short opinion survey, students were polled to evaluate their experience. Student preferences for both learning and testing method varied widely.

Bone and Bones↗