PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9447668

A least-squares strain estimator for elastography.

F Kallel·J Ophir
View original source ↗Export metadata ↓

Abstract

A least-squares strain estimator (LSQSE) for elastography is proposed. It is shown that with such an estimator, the signal-to-noise ratio in an elastogram (SNRe) is significantly improved. This improvement is illustrated theoretically using a modified strain filter and experimentally using a homogeneous gel phantom. It is demonstrated that the LSQSE results in an increase of the elastographic sensitivity (smallest, strain that could be detected), thereby increasing the strain dynamic range. Using simulated data, it is shown that a tradeoff exists between the improvement in SNRe and the reduction of strain contrast and spatial resolution.

Explore related subjects

Connective TissueElasticityFiltrationHumansLeast-Squares AnalysisModels, BiologicalModels, StatisticalPhantoms, ImagingSignal Processing, Computer-AssistedUltrasonographyJournal ArticleResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F Kallel, J Ophir. 1997. A least-squares strain estimator for elastography.. https://doi.org/10.1177/016173469701900303

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

KEEP EXPLORING

Related citations

PubMed2007

Bilaminar connective tissue graft as an alternative treatment of leukoplakia: case report.

Oral leukoplakia is a predominantly white lesion of the oral mucosa that cannot be clinicopathologically characterized as any other definable lesion. Any oral site may be affected by leukoplakia, the most common sites being buccal and alveolar mucosa, floor of the mouth, tongue, lips, and palate. To date there is no evidence of effective treatment of oral leukoplakia that may prevent recurrence. This case report describes a new surgical technique using a bilaminar connective tissue graft in the treatment of oral leukoplakia. During the regular periodontal recall visit, the clinical diagnosis of gingival leukoplakia at the maxillary left sextant was established in a 45-year-old patient. Histopathologic analysis suggested reactive hyperkeratosis. The patient agreed to a new surgical treatment of the lesion. Under local anesthesia a 20-mm-long bilaminar connective tissue graft was interposed between the affected tissue and the bone. Healing was followed by the disappearance of the white lesion within the borders of the underlying graft. Five years after therapy, the treated area remained intact, with no clinical sign of recurrence.

Connective Tissue↗
PubMed2006

Hypospadias and associated penile anomalies: a histopathological study and a reconstruction of the pathogenesis.

Hypospadias is considered to be the result of inadequate fusion of urethral folds and, possibly, of canalization of a glandar epithelial cord during the formation of the spongy urethra. This theory had to be reconsidered because a recent study in normal human embryos has exposed such fusion and invagination as misconceptions. Autopsy specimens of five penises with hypospadias from foetuses and neonates were studied histologically. The findings complemented with data from the literature were correlated to the normal developmental process to reconstruct the pathogenesis of the disorder. Histopathological analysis revealed that the hypospadic orifice was the proximal part of a mucosal delta which revealed the structure of the roof and meatus of a flattened distal urethra. Branches of the raphe bordering the delta and terminating in prominent 'dog ears' had the characteristics of the transient urethral labia (folds). Associated curvature and torsion could be related to structural abnormalities of vascular structures, notably the distal corpus spongiosum, and fasciae predominantly proximal to the hypospadic orifice. Correlation with normal development indicated that hypospadias and associated anomalies are not caused by disturbed fusion or glandar invagination but by maldevelopment of a complex of primordial fascial and vascular tissue proximal to the urethral orifice which normally form the venter side of the penis by disproportionately strong proliferation and make the urethral orifice shift distalward. Insufficient growth may disturb that shift with the degree of deficiency determining the precise position of the urethral orifice, size of the urethral delta and defect of the prepuce. Shortage and/or poor organisation of these tissues explain curvature and, if asymmetrical, torsion, both of which can occur also with minimal urethral deformity or as congenital ventral curvature and torsion without hypospadias.

Connective Tissue↗