Temporal averaging of two-dimensional correlation functions for velocity vector imaging of cardiac blood flow

Improving image contrast and accuracy in velocity estimation by convolution filters for intracardiac blood flow imaging

In this study, the point spread function (PSF) of an ultrasound imaging system was estimated and used as a reference signal in a filtering method for improvement of image quality. The PSF of the imaging system was estimated from measured echo signals from an imaging target. Convolution filters (including deconvolution) were used for improvement of image contrast and spatial resolution. Furthermore, the accuracy in estimation of velocity vectors was evaluated for investigation of the impact of the proposed filters on velocity estimation. In the phantom experiment, contrast of the B-mode image was improved from 76.4 dB to 81.1 dB and 77.8 dB using the convolution and deconvolution filters, respectively. Also, the two-dimensional (2D) velocity distribution in the phantom was estimated by the block matching method, and the bias error (BE) in the estimated lateral velocity was reduced from -19.7% to 2.16% and 2.29% using the convolution and the deconvolution filters, respectively.

Involvement of the Areae Compositae of the Heart in Endemic Pemphigus Foliaceus

Background

A new variant of endemic pemphigus foliaceus in El Bagre (El Bagre-EPF), Colombia, South America, shares features with Senear-Usher syndrome and occurs in an endemic fashion. Patients affected by El Bagre-EPF have heterogeneous antigenic reactivity not only to the skin but to other organs, including the heart. Here we test for autoantibodies to the areae compositae of the heart (structure consisting of typical desmosomal amalgamated fascia adherens molecules) and evaluate any possible clinical correlation.

Methods

A case-control study comparing 45 patients and 45 controls from the endemic area, matched by demographics including age, gender, weight, work activities, and comorbidities, was performed. Direct and indirect immunofluorescence, immunohistochemistry, confocal microscopic studies, and echocardiogram studies were completed.

Results

The main clinical abnormally seen in the El Bagre-EPF patients was left ventricular hypertrophy in 15/45 patients, compared with no such findings in the control population (P < 0.1). Seventy percent of El Bagre-EPF patients and none of the controls displayed polyclonal autoreactivity using different immunoglobulins and complement to the areae compositae of the heart using different methods and antibodies (P < 0.1).

Conclusions

Patients affected by El Bagre-EPF demonstrated autoantibodies to the areae compositae of the heart. This finding was associated with left ventricular hypertrophic cardiomyopathy. The areae compositae may play a role in cell junction tension and the El Bagre-EPF patients' autoantibodies possibly disrupting these junctions and thereby contributing to the left ventricular hypertrophy.

Identification of vascular lumen by singular value decomposition filtering on blood flow velocity distribution

PURPOSE

In the present study, we proposed a novel method for identification of the vascular lumen by employing singular value decomposition (SVD), and the feasibility of the proposed method was validated by in vivo measurement of the common carotid artery.

METHOD

SVD filtering was applied to a velocity map that was estimated using an autocorrelation method to identify the lumen region. In this study, the packet size was set at 999 frames with a frame rate of 1302 Hz. The region estimated by the proposed SVD filtering was compared with that estimated by the conventional power Doppler method.

RESULT

The averaged differences in feature values between vascular wall and lumen regions obtained by the proposed and conventional methods were 34 dB and 26 dB, respectively. The proposed method was hardly influenced by the cardiac phase and could separate the wall and lumen regions more stably. The proposed method could identify the lumen region by setting a threshold of - 28 dB from the averaged difference amplitude.

CONCLUSION

We proposed a novel method for identification of the vascular lumen. The proposed method could suppress the effects of wall motion, which was present in the conventional power Doppler image. The lumen region identified by the proposed method well conformed with the anatomical information in the B-mode image of the corresponding section.