Hybrid Ultrasonic Computed Tomography

Azhari, Haim; Stolarski, Silvia

doi:10.1006/cbmr.1997.1439

Cited by 9 publications

(6 citation statements)

References 15 publications

(14 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition to the super-resolution acquisition, a modified form of an iterative algorithm called hybrid computed tomography (HCT), implemented previously on ultrasonic CT data [10], was utilized here to fuse CT anatomical data with the PET functional data. The HCT algorithm is based on a two-dimensional (2D) Taylor series expansion of the gray levels which incorporates texture and edge information.…”

Section: Methodsmentioning

confidence: 99%

“…Neglecting higher-order terms, the modified 2D Taylor expansion about pixel ( a, b ) has a value f ( x, y ) at pixel ( x, y ) [10]:

f (x, y) = f (a, b) + true[(x - a) \cdot \frac{\partial f}{\partial x} {true|}_{a, b} + (y - b) \cdot \frac{\partial f}{\partial y} {true|}_{a, b} true] \cdot β (a, b),

where the function β ( x, y ) has a zero value within homogeneous regions but is set to have a value of 1 at boundary points. In the PET/CT application, the function β can be obtained from the anatomical edge data of the CT scan.…”

Section: Methodsmentioning

confidence: 99%

“…The algorithm we used to incorporate CT data in PET images is called hybrid computed tomography (HCT). HCT was originally developed for artifact reduction in ultrasonic computed tomography [10]. In regions not containing anatomical edges, HCT has been shown to provide noise reduction in PET images equivalent to the standard Gaussian filtering typically used [11].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improved Image Fusion in PET/CT Using Hybrid Image Reconstruction and Super‐Resolution

Kennedy

Israel

Frenkel

et al. 2006

International Journal of Biomedical Imaging

Self Cite

View full text Add to dashboard Cite

Purpose. To provide PET/CT image fusion with an improved PET resolution and better contrast ratios than standard reconstructions. Method. Using a super-resolution algorithm, several PET acquisitions were combined to improve the resolution. In addition, functional PET data was smoothed with a hybrid computed tomography algorithm (HCT), in which anatomical edge information taken from the CT was employed to retain sharper edges. The combined HCT and super-resolution technique were evaluated in phantom and patient studies using a clinical PET scanner. Results. In the phantom studies, 3 mm18F-FDG sources were resolved. PET contrast ratios improved (average: 54%, range: 45%–69%) relative to the standard reconstructions. In the patient study, target-to-background ratios also improved (average: 34%, range: 17%–47%). Given corresponding anatomical borders, sharper edges were depicted. Conclusion. A new method incorporating super-resolution and HCT for fusing PET and CT images has been developed and shown to provide higher-resolution metabolic images.

show abstract

Section: Methodsmentioning

confidence: 99%

“…Neglecting higher-order terms, the modified 2D Taylor expansion about pixel ( a, b ) has a value f ( x, y ) at pixel ( x, y ) [10]:

f (x, y) = f (a, b) + true[(x - a) \cdot \frac{\partial f}{\partial x} {true|}_{a, b} + (y - b) \cdot \frac{\partial f}{\partial y} {true|}_{a, b} true] \cdot β (a, b),

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improved Image Fusion in PET/CT Using Hybrid Image Reconstruction and Super‐Resolution

Kennedy

Israel

Frenkel

et al. 2006

International Journal of Biomedical Imaging

Self Cite

View full text Add to dashboard Cite

show abstract

“…1 This has led to the development of the field of elastography. Although magnetic resonance elastography has been extensively investigated, 4,5 the modality prevailing in the field is ultrasound. In conventional ultrasonic imaging, stiffer tissue does not necessarily depict the substantial change in its sonographic properties.…”

mentioning

confidence: 99%

A Method for Characterization of Tissue Elastic Properties Combining Ultrasonic Computed Tomography With Elastography

Glozman

Azhari

2010

Journal of Ultrasound in Medicine

Self Cite

View full text Add to dashboard Cite

Objective. The correlation between various diseases and the change in the local mechanical properties of soft tissues has been long known. Over the past 20 years, there have been increasing research efforts to characterize mechanical properties of biological tissues using ultrasonic elastography. However, most of these works were based on characterization of only 1 type of waves (longitudinal or shear). The goal of this work was to devise a comprehensive ultrasound-based imaging method capable of measuring elastic parameters by combining both backscattered elastography and throughtransmitted ultrasonic computed tomography. Methods. Our suggested technique provides measurements of both longitudinal and shear wave velocities. This enables the noninvasive computation of several tissue elasticity parameters such as Young's and shear moduli, Poisson's ratio, and, more importantly, the bulk modulus, the determination of which requires both wave velocities. Four different phantom types were examined: agar-gelatin-based phantoms and porcine fat tissue, turkey breast tissue, and bovine liver tissue in vitro specimens. The values of Young's modulus, the shear modulus, and Poisson's ratio were estimated and were consistent with values published in the literature. Results. The average bulk modulus values of the phantoms ± SD were 2.83 ± 0.001, 2.25 ± 0.01, 2.48 ± 0.01, and 2.53 ± 0.02 GPa, respectively. A statistically significant difference (P < .001) in the values of the bulk modulus of the different phantoms was found. Conclusions. The bulk modulus is suitable for differentiation between different tissue types. The obtained results show the feasibility of using a comprehensive ultrasonic imaging technique for noninvasive quantitative tissue characterization. Key words: bulk modulus; computed tomography; elastic parameters; elastography; tissue characterization; wave velocity. 2 However, in many cases, the small size of a pathologic lesion or its location deep in the body makes its detection and evaluation by palpation difficult or impossible. Furthermore, palpation is nonquantitative and lacks accuracy in locating the lesion.

show abstract

“…The scanning system utilized to measure the plastic specimens is comprised of a water-bath with a specially built computer-controlled mechanism that can produce spatial motion with three degrees of freedom for a pair of transducers (Panametrics, 5 MHz, focused transducers, diameter 12.7 mm and focal length 10.7 cm) placed about twice the focal length apart (Azhari and Stolarski 1997;Azhari and Sazbon 1999). The system can scan a cylindrical volume defined by the user (up to 20 cm in diameter and 10 cm in height) located at the center of the water bath.…”

Section: Ultrasonic Measurementsmentioning

confidence: 99%

Measurement of speed of sound dispersion in soft tissues using a double frequency continuous wave method

Levy

Agnon

Azhari

2006

Ultrasound in Medicine & Biology

Self Cite

View full text Add to dashboard Cite

Hybrid Ultrasonic Computed Tomography

Cited by 9 publications

References 15 publications

Improved Image Fusion in PET/CT Using Hybrid Image Reconstruction and Super‐Resolution

Improved Image Fusion in PET/CT Using Hybrid Image Reconstruction and Super‐Resolution

A Method for Characterization of Tissue Elastic Properties Combining Ultrasonic Computed Tomography With Elastography

Measurement of speed of sound dispersion in soft tissues using a double frequency continuous wave method

Contact Info

Product

Resources

About