Biomedical subjects

P Giat

Publications and source records attributed to P Giat.

4 recordsLinked to original sources

PubMed1994

Broadband ultrasonic attenuation imaging: a new imaging technique of the os calcis.

Ultrasound transmission measurement through the os calcis is an emerging technique and a promising clinical tool for early assessment of osteoporosis. However, several previous studies showed that broadband ultrasonic attenuation (BUA) is sensitive to small variations in bone mass or structure. The os calcis is an inhomogeneous bone and therefore, the attenuation depends on the location in the os calcis. BUA distribution within the os calcis can be measured by rectilinear scanning over the entire bone. We used a mechanical scanning device with both unfocused and focused transducers. The spatial resolution of these was about 25 mm and 4 mm, respectively. There was good agreement (r = 0.97) between the results with unfocused and focused transducers. In addition, imaging the variations of BUA is possible with the focused transducers, and high quality images are obtained. These images permit the selection of optimal regions of interest for ultrasound attenuation measurement.

Aged↗

PubMed1994

Ultrasound attenuation imaging in the os calcis: an improved method.

A complete assessment of the broadband ultrasonic attenuation (BUA) distribution within the os calcis was made using an ultrasonic mechanical scanning device with focused transducers. Measurements were performed on 12 os calces removed from fresh female cadavers. We present the first images of BUA of the os calcis. Reasonably high quality images were obtained compared to computed tomography. The resolution provided by the focused transducers is approximately 4 or 5 mm in the focal zone. Compared to dual energy X-ray absorptiometry (DEXA) or quantitative computed tomography, ultrasound imaging of the os calcis offers the possibility of controlling the placement, size and shape of the region of interest and to use multiple measurement sites. DEXA was used systematically to measure the bone mineral density (BMD) of the os calces. A highly significant correlation between BMD and BUA was found (r = 0.97 p < 0.001).

Absorptiometry, Photon↗

PubMed1994

Bone characterization with ultrasound: state of the art and new proposal.

Ultrasound transmission measurement through the os calcis is an emerging technique and a promising clinical tool for early assessment of osteoporosis. In this paper we first present a short discussion on the physical meaning of ultrasound velocity and attenuation, the methods of measurements and the potential contribution of ultrasound compared to photon absorptiometry. After analysing the various results in vivo published up to now we shall present some new perspectives of ultrasonic bone characterization: broadband ultrasonic attenuation imaging (BUAI) and pulse-echo measurement.

Absorptiometry, Photon↗

PubMedDate not supplied

Technical developments in cardiac CT: 2000 update.

Preliminary results of the new generation CT scanners in the study of the heart and coronary arteries, are reported, after an overview of basic anatomy, physiology and main technical problems. Comparison is made with the other conventional procedures. The clinical validation of cardiac CT is under way while preliminary results are very encouraging. However, for cardiac CT to become an examination of first choice in the study of the heart and coronary arteries, spatial resolution should be improved and acquisitions of 15 cm volume with less than 15 sec breath-hold should be feasible. The improvement in cardiac synchronization and temporal resolution will allow a kynetic systolic as well as diastolic study. This is going to be possible with the new generation CT scanners able of 16 or 32 sections per second.

Coronary Angiography↗