Ultrasonography in the staging of Hodgkin's disease: lymphangiographic correlation

The effect of logarithmic compression on estimation of the Nakagami parameter for ultrasonic tissue characterization: a simulation study

Previous studies have demonstrated that the Nakagami parameter estimated using the envelopes of backscattered ultrasound is useful in detecting variations in the concentration of scatterers in tissues. The signal processing in those studies was linear, whereas nonlinear logarithmic compression is routinely employed in existing ultrasonic scanners. We therefore explored the effect of the logarithmic compression on the estimation of the Nakagami parameter in this study. Computer simulations were used to produce backscattered signals of various scatterer concentrations for the estimation of the Nakagami parameters before and after applying the logarithmic compression on the backscattered envelopes. The simulated results showed that the logarithmic compression would move the statistics of the backscattered envelopes towards post-Rayleigh distributions for most scatterer concentrations. Moreover, the Nakagami parameter calculated using compressed backscattered envelopes is more sensitive than that calculated using uncompressed envelopes in differentiating variations in the scatterer concentration, making the former better at quantifying the scatterer concentration in biological tissues.

Ultrasonically guided percutaneous splenic tissue core biopsy in patients with malignant lymphomas

Ultrasonically (US) guided percutaneous tissue core biopsy of the spleen was done on 46 patients with malignant lymphomas. The biopsies were undertaken as a staging procedure in 32 patients, as a restaging procedure in 7, during follow-up in 2, and as a diagnostic step in 5 (previously undiagnosed cases with clinically and ultrasonographically suspected lymphoma). In 45 patients, the tissue core specimens obtained by US-guided biopsies were sufficient for a correct histologic examination; in one patient, the specimen was considered inadequate. The tissue core specimens showed splenic involvement in 12 patients and normal splenic tissue in the other 33. These latter cases were confirmed by splenectomy, by laparoscopy with larger splenic biopsy needles, and by clinical and US follow-up over a period of 6 to 30 months. In all previously undiagnosed patients (five), splenic biopsies allowed histologic subtyping. Additional immunologic subclassification into B-cell and T-cell types of lymphomas was done in two instances. There were no complications in this series. These results suggest that percutaneous US-guided splenic tissue core biopsy is a useful and safe technique for the diagnosis, staging, and follow-up of malignant lymphoma.

Ultrasonic multifeature maps of liver based on an amplitude loss technique and a conventional B-scan

Recently, a novel ultrasonic amplitude loss technique for creating images of local tissue attenuation was presented. Based on this algorithm, global attenuation estimates were calculated and consistent variations of the estimated attenuation value was observed for different liver pathologies. With the exception of Hodgkin's and acute inflammatory liver disease, the detectability of the disease states was not increased by the global attenuation estimates. In an attempt to do so, pseudo-color maps were used in this study. The conventional B-scan was presented as a grey-scale image and a color-code attribute was based on the local attenuation estimate. In the vicinity of strong reflectors we noted a typical artifact. Modification of the classical physical model, describing the ultrasonic-tissue interaction, was observed to reduce the artifacts in the attenuation estimates; however, the detectability of disease states was not increased.

Local tissue attenuation images based on pulsed-echo ultrasound scans

This paper presents a novel technique for creating images of local tissue attenuation. The original conventional B scan is traversed, one pixel at a time. In the vicinity of each pixel, a uniform area is determined and average attenuation is computed utilizing an extended modified Prony approach. B scans of tissue mimicking phantoms and in vivo human liver scans are used in order to illustrate the performance of the proposed algorithm. The results show good agreement between estimated and known attenuation values. Clinical studies demonstrate significant potential of the proposed technique, in particular for diagnosis of diffuse liver disease.