Fast 2D Convolutions and Cross-Correlations Using Scalable Architectures.

The manuscript describes fast and scalable architectures and associated algorithms for computing convolutions and cross-correlations. The basic idea is to map 2D convolutions and cross-correlations to a collection of 1D convolutions and cross-correlations in the transform domain. This is accomplished through the use of the discrete periodic radon transform for general kernels and the use of singular value decomposition -LU decompositions for low-rank kernels. The approach uses scalable architectures that can be fitted into modern FPGA and Zynq-SOC devices. Based on different types of available resources, for P×P blocks, 2D convolutions and cross-correlations can be computed in just O(P) clock cycles up to O(P2) clock cycles. Thus, there is a trade-off between performance and required numbers and types of resources. We provide implementations of the proposed architectures using modern programmable devices (Virtex-7 and Zynq-SOC). Based on the amounts and types of required resources, we show that the proposed approaches significantly outperform current methods.

Fast and Scalable Computation of the Forward and Inverse Discrete Periodic Radon Transform.

The discrete periodic radon transform (DPRT) has extensively been used in applications that involve image reconstructions from projections. Beyond classic applications, the DPRT can also be used to compute fast convolutions that avoids the use of floating-point arithmetic associated with the use of the fast Fourier transform. Unfortunately, the use of the DPRT has been limited by the need to compute a large number of additions and the need for a large number of memory accesses. This paper introduces a fast and scalable approach for computing the forward and inverse DPRT that is based on the use of: a parallel array of fixed-point adder trees; circular shift registers to remove the need for accessing external memory components when selecting the input data for the adder trees; an image block-based approach to DPRT computation that can fit the proposed architecture to available resources; and fast transpositions that are computed in one or a few clock cycles that do not depend on the size of the input image. As a result, for an N × N image (N prime), the proposed approach can compute up to N(2) additions per clock cycle. Compared with the previous approaches, the scalable approach provides the fastest known implementations for different amounts of computational resources. For example, for a 251×251 image, for approximately 25% fewer flip-flops than required for a systolic implementation, we have that the scalable DPRT is computed 36 times faster. For the fastest case, we introduce optimized just 2N + ⌈log(2) N⌉ + 1 and 2N + 3 ⌈log(2) N⌉ + B + 2 cycles, architectures that can compute the DPRT and its inverse in respectively, where B is the number of bits used to represent each input pixel. On the other hand, the scalable DPRT approach requires more 1-b additions than for the systolic implementation and provides a tradeoff between speed and additional 1-b additions. All of the proposed DPRT architectures were implemented in VHSIC Hardware Description Language (VHDL) and validated using an Field-Programmable Gate Array (FPGA) implementation.

Computational basis for risk stratification of peripheral neuropathy from thermal imaging.

The goal of this paper is to present a computer-based system for analyzing thermal images in the detection of preclinical stages of peripheral neuropathy (PN) or diabetic foot. Today, vibration perception threshold (VPT) and sensory tests with a monofilament are used as simple, noninvasive methods for identifying patients who have lost sensation in their feet. These tests are qualitative and are ineffective in stratifying risk for PN in a diabetic patient. In our system a cold stimulus applied to the foot causes a thermoregulatory and corresponding microcirculation response of the foot. A thermal video monitors the recovery of the microcirculation in the foot plantar. Thermal videos for 8 age-matched subjects were analyzed. Six sites were tracked and an average thermal emittance calculated. Characteristics of the recovery curve were extracted using coefficients from an exponential curve fitting process and compared among subjects. The magnitude of the recovery was significantly different for the two classes of subjects. Our system shows evidence of differences between both groups, which could lead to a quantitative test to screen and diagnose peripheral neuropathy.

Utilidad del strain miocardico en el estudio de la cardiopatia coronaria / Utility of myocardial strain in the study of coronary cardiopathy

Introduccion: El proceso de deformación (D) miocárdica (M) durante el ciclo cardíaco depende de las propiedades elásticas y de las fuerzas involucradas en la contracción del segmento analizado. Estudios clínicos y en corazón animal, han demostrado superioridad de la estimación de la D longitudinal por Strain (S) y Strain rate (SR) mediante Eco Doppler tisular pulsado (DTP) y Doppler Color (DCM), sobre la simple estimación visual de motilidad, con el fin detectar necrosis y/o cambios inducidos por isquemia (isq)...

Utilidad del doppler tissular en el analisis del septum interventricular post cirugia cardíaca con circulacion extra corporea / Utility of tissue doppler echocardiography in analisis of interventricular septum after cardiac surgery with cardiopulmonary bypass

La motilidad del septum interventricular (SIV) post cirugía cardiaca con circulación extracorpórea (CEC) tiene dinámica multifactorial y su evaluación con eco 2D y M es en parte subjetiva. El objetivo de este estudio es analizar su motilidad con Doppler tisular(DT), evaluar su contractilidad (C) con Strain (S) y compararlas con un grupo control.

Transthoracic Versus Transesophageal Two-Dimensional Echo Doppler Determination of Flow Velocity in the Left Atrial Appendage.

The assessment of flow velocity (FV) in the left atrial appendage (LAA) by transesophageal echocardiography (TEE) has been reported to be a useful tool as a high risk marker for systemic emboli. The analysis of FV in LAA by transthoracic echocardiography (TTE) has not yet been validated. The purpose of this study was to compare FV measurements in the LAA by TEE and TTE in 30 consecutive patients (age 19-87 years, mean = 55) sent for echocardiographic study with the following diagnosis: stroke (11 patients), mitral stenosis (6 patients), congenital heart disease (4 patients), mitral prosthetic function assessment (2 patients), and other pathologies (7 patients). FV was measured at the outlet and mid-portion of the LAA with TTE, from the apical two-chamber view and with biplane TEE, from the longitudinal two-chamber view. Satisfactory measurements were obtained with TTE from the outlet of the LAA in 96.7% and from the mid-portion of the LAA in 90% of patients. One third of patients were in atrial fibrillation (AF) during the study. The mean FV in the outlet of the LAA was 32.7 +/- 2.5 (SE) cm/sec with TTE and was 33.7 +/- 3.04 (SE) cm/sec with TEE (r = 0.95). The mean FV in the mid-portion of the LAA was 40.9 +/- 3.3 and 42.7 +/- 3.9 with TTE and TEE respectively (P = NS) (r = 0.95). There was no difference in the LAA FV determination by TTE and TEE in the subgroup with AF. TTE was able to detect FV < 30 cm/sec with a sensitivity of 88% and specificity of 81% and a positive predictive value of 84% compared with TEE.

Estenosis mitral: evaluación por ecocardiografía bidimensional y Doppler; informe preliminar / Mitral stenosis: evaluation by dimensional and Doppler echocardiography; preliminary report

Se estudian 25 pacientes portadores de estenosis mitral pura, de los cuales 6 presentan además fibrilación auricular. Se analiza la determinación del área valvular mitral por ecocardiografía bidimensional y ecocardiografía Doppler, mostrándose que entre ambos métodos existe una correlación estadísticamente válida. Se logra demostrar también que los pacientes portadores de estenosis más severa tienen mayor grado de dilatación de aurícula izquierda. Por último, se concluye que los pacientes portadores de estenosis mitral que presentan fibrilación auricular corresponden a los grados más críticos de estenosis y de dilatación auricular izquierda

Prolapso valvular mitral y embarazo: análisis de 90 casos / Mitral valve prolapse and pregnancy: analysis of 90 cases

El prolapso valvular mitral (PVM) es actualmente la cardiopatía congénita más frecuente, con una incidencia cercana al 6%. Nuestra serie analiza 90 embarazos en 39 pacientes con PVM diagnosticado como hallazgo auscultatorio y ecocardiográfico. Los resultados señalan una excelente tolerancia al embarazo en todas las pacientes sin complicaciones cardíacas relevantes (arrtmia severa, insuficiencia cardíaca, endocarditis bacteriana subaguda (EBSA) o embolias). No se observaron diferencias estadísticamente significativas (P < 0,05) en la morbilidad materna, en la morbimortalidad perinatal, al comparar el grupo control con el grupo PVM.