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PubMed1987

Effects of statistical noise and digital filtering on the parameters calculated from the impulse response function.

Radiotracers are widely used for the investigation of organ perfusion and function. One of the quantitative approaches to analyze radiotracer data is the calculation of the impulse response function, which is obtained by deconvolution analysis of the time-activity curves measured over the organ. Since exactness of the calculated impulse response function depends both on the counting statistics and on the deconvolution algorithm applied, computer simulated time-activity curves were used to test the least squares deconvolution program based on the matrix regularization algorithm. Criteria of clinical importance (error in the calculated organ function parameters) and criteria of mathematical importance (deconvolution and reconvolution error) were investigated. For three typical impulse response functions f(t), it was found that: 1. In cases of noncompartmental vascular-capillary f(t)'s, a high degree of smoothing is preferable during deconvolution, in this way the error becomes systematic but controllable. 2. Noncompartmental vascular-tubular f(t)'s are noise sensitive, but fortunately, noise in the data can be held to a minimum. 3. Compartmenta f(t)'s need only a minimal degree of smoothing; their components can be identified in a second step using a multiexponential least squares fit.

Algorithms↗
PubMed2005

Computerized separation of chromatographically unresolved peaks.

A computerized peak deconvolution software and mass spectra were successfully applied for the deconvolution of overlapped peak cluster in the chromatogram obtained separating the complex mixture of pesticides by retention time locking gas chromatography-mass spectroscopy. The method based on the unique fragment ions in the spectra can be used for deconvolution of peak clusters if mass spectra of overlapped peaks differ. This method allows determining actual retention times of overlapped peaks. Peak areas found by this method however, cannot be used naturally for the quantitative purposes as the abundance of fragment ions used for this deconvolution procedure can dramatically differ. Computer assisted deconvolution of peaks in the peak clusters gives more realistic peak area ratios as at this method it is supposed equal response for all peaks overlapped in a cluster.

Gas Chromatography-Mass Spectrometry↗
PubMed2006

Using voxel-specific hemodynamic response function in EEG-fMRI data analysis.

Most existing analytical techniques for EEG-fMRI data need specific assumptions about the hemodynamic response function (HRF). These assumptions may not be appropriate when the HRF varies from subject to subject or from region to region. In this article, we introduce a deconvolution method for EEG-fMRI activation detection, which can be implemented with voxel-specific HRFs. A comparison of performance is made between three fixed HRFs and the deconvolution method under the framework of the general linear model. The main results are as follows: (1) the volume of detected regions from the deconvolved HRFs is larger. (2) In some subjects, the deconvolution technique can find areas of activation that have not been detected with the three fixed HRFs at our threshold of significance. (3) Deconvolution obtained higher adjusted coefficients of multiple determination compared to those obtained with the three fixed HRFs. The results suggest that the fixed HRF methods may not be the most appropriate for the analysis of epileptic activity with EEG-fMRI, and the deconvolution method may be a better choice.

Brain↗
PubMed2006

Spectral unmixing of multicolored bioluminescence emitted from heterogeneous biological sources.

A wide variety of bioluminescent luciferase proteins are available for use in transcriptional or biochemical reporter assays. However, spectral overlap normally prevents them from being monitored simultaneously. To address this problem, a Java plug-in for ImageJ was written to deconvolute bioluminescent images composed of signals from multiple luciferases. The methodology was validated by testing the program with both simulated and real luciferase images. Bioluminescent images were acquired using a CCD camera equipped with optical filters, and the images were deconvoluted using the ImageJ plug-in. HeLa cells were transfected with either click beetle red luciferase (CBR), click beetle green luciferase (CBG99), or Renilla luciferase (Rluc), and mixed lysates were imaged in varying proportions in a 96-well plate to biochemically validate the methodology. After spectral deconvolution, the predicted, pure luciferase signals could be recovered with maximal cross-talk errors of +/-1.5%. In addition, live cells expressing CBR, CBG99, and Rluc were simultaneously imaged and deconvoluted in 96-well plates to demonstrate the feasibility of applying this methodology to high-throughput applications. Finally, multicolor transcriptional and posttranslational modification reporters were simultaneously imaged and shown to deconvolute normalized IkappaBeta kinase activity in longitudinal assays. Thus, our software provided a rapid, simple, and accurate method for simultaneously measuring multiple bioluminescent reporters in living cells.

Cell-Free System↗
PubMedDate not supplied

Ruminations regarding the design of small mixtures for biological testing.

Synthesis and screening of compound mixtures offer avenues to increase throughput and reduce cycle time in the discovery of new drugs and agrochemicals. Equations are derived which show that the efficiency of synthesis and screening of mixtures is a function of the screening hit rate and the number of compounds in each mixture when simple one-step deconvolution by retesting the individual compounds in each active mixture is employed. Values of hit rate and number of compounds in each mixture which afford various levels of increased efficiency are delineated. Two-step deconvolution, in which the active mixtures from the first round of testing are subdivided into mixtures with fewer compounds for a second round of mixture screening prior to final testing of individual compounds, is shown to be more efficient than simple one-step deconvolution under most conditions. For optimum efficiency, the number of compounds in each mixture in the second round testing should be the square root of the number of compounds in each mixture in the first round. At high hit rates the efficiency of the double scan or indexed approach to deconvolution is shown to be higher than that of simple deconvolution. This discussion is oriented mainly toward mixtures of 4-20 compounds and screens which give hit rates in the 1-10% range. The equations describing efficiency are applied in the context of a 49-member amide library produced as mixtures of seven compounds. This library includes the commercial herbicide pronamide and was screened for herbicidal and insecticidal utility.

Combinatorial Chemistry Techniques↗
PubMed2005

Tracer delay correction of cerebral blood flow with dynamic susceptibility contrast-enhanced MRI.

Cerebral blood flow (CBF) and vascular mean transit time (MTT) can be determined by dynamic susceptibility contrast-enhanced magnetic resonance imaging and deconvolution with an arterial input function. However, deconvolution by a singular value decomposition (SVD) method is sensitive to the tracer delay that often occurs in patients with cerebrovascular disease. We investigated the effect of tracer delay on CBF determined by SVD deconvolution. Simulation study showed that underestimation of CBF due to tracer delay was larger for shorter MTTs. We developed a delay correction method that determines tracer delay by means of least-squares fitting pixel-by-pixel. The corrected CBF was determined by SVD deconvolution after time-shifting of the measured concentration curve. The simulations showed that the corrected CBF was insensitive to tracer delay irrespective of the vascular model, although CBF fluctuation increased slightly. We applied the delay correction to the CBF and MTT images acquired for nine patients with hyperacute stroke and unilateral occlusion of the middle cerebral artery. We found in some patients that the delay correction modulated the contrast of CBF and MTT images. For hyperacute stroke patients, tracer delay correction is essential to obtain reliable perfusion image when SVD deconvolution is used.

Acute Disease↗
PubMed1999

Hepatic extraction fraction of hepatobiliary radiopharmaceuticals measured using spectral analysis.

Measuring the hepatic extraction fraction (HEF) of a hepatobiliary radiopharmaceutical helps to differentiate hepatocyte from biliary tract diseases, and it is generally performed using deconvolution analysis. In this study, we measured HEF using spectral analysis. With spectral analysis, HEF was calculated from (the sum of the spectral data obtained by spectral analysis--the highest frequency component of the spectrum) divided by (the sum of the spectral data) x 100 (%). We applied this method to dynamic liver scintigraphic data obtained from six healthy volunteers and from 46 patients with various liver diseases, using 99Tcm-N-pyridoxyl-5-methyltryptophan (PMT). We also measured HEF using deconvolution analysis, in which the modified Fourier transform technique was employed. The HEF values obtained by spectral analysis correlated closely with those obtained by deconvolution analysis (r = 0.925), suggesting our method is valid. The HEF values obtained by spectral analysis decreased as the severity of liver disease progressed. The values were 100.0 +/- 0.0%, 94.7 +/- 13.6%, 76.2 +/- 27.4%, 45.7 +/- 15.6%, 82.7 +/- 24.2% and 95.2 +/- 11.8% (mean +/- S.D.) for the normal controls (n = 6), mild liver cirrhosis (n = 16), moderate liver cirrhosis (n = 11), severe liver cirrhosis (n = 5), acute hepatitis (n = 8) and chronic hepatitis groups (n = 6), respectively. The HEF was obtained more simply and rapidly by spectral analysis than by deconvolution analysis. The results suggest that our method using spectral analysis can be used as an alternative to the conventional procedure using deconvolution analysis for measuring HEF.

Aged↗
PubMed2005

A method for differentiating ocular higher-order aberrations from light scatter applied to retinitis pigmentosa.

PURPOSE: The purpose of this study is to report a method for differentiating ocular higher-order aberrations and intraocular light scatter based on a deconvolution technique. METHODS: An optical system was used to image a laser slit on the retina and also to perform Shack-Hartmann wavefront sensing. From the laser slit image, the line spread function, incorporating both ocular higher-order aberrations and light scatter, was derived. The laser slit image was deconvolved with a point spread function obtained from the Shack-Hartmann image. The area under the line spread function that was derived from the laser slit image after deconvolution provided a measurement of intraocular light scatter. The deconvolution technique was applied to images obtained in a group of 13 patients (mean age +/- 1 standard deviation: 42 +/- 12 years) with retinitis pigmentosa (RP), a retinal disease in which, by clinical examination, changes in the lens of the eye can be manifested. Measurements were compared with those obtained from 20 visually normal control subjects (mean age +/- 1 standard deviation: 43 +/- 17 years). RESULTS: Combined higher-order aberrations and light scatter, measured as the area under the line spread function derived from the laser slit image, were increased significantly in the patients with RP as compared with the control subjects (p = 0.004). Ocular higher-order aberrations obtained from the Shack-Hartmann images were higher in the patients with RP than in the control subjects (p = 0.05). Intraocular light scatter derived from the deconvolved laser slit image was significantly higher in the patients with RP than in the control subjects (p = 0.009). Minimizing the contribution of ocular higher-order aberrations by deconvolution reduced the area under the line spread function in the control subjects and patients with RP, denoting an improvement in retinal image quality. CONCLUSIONS: A method for differentiating ocular higher-order aberrations and intraocular light scatter based on deconvolution was developed that may be useful for determining the level of improvement in retinal image quality that can be anticipated by the application of adaptive optics to aging and diseased human eyes.

Adult↗
PubMed2002

Magnetic resonance perfusion-weighted imaging of acute cerebral infarction: effect of the calculation methods and underlying vasculopathy.

BACKGROUND AND PURPOSE: Various calculation methods are available to estimate the transit-time on MR perfusion-weighted imaging (PWI). Each method may affect the results of PWI. Steno-occlusive disease in the parent vessels is another factor that may affect the results of the PWI. The purpose of this study was to elucidate the effect of the calculation methods and underlying vasculopathy on PWI. METHODS: From a pool of 113 patients who had undergone PWI during the study period, a total of 12 patients with nonlacunar ischemic strokes who were scanned within 24 hours after onset of symptom were selected for the study. The patient population consisted of 6 patients who had extracranial internal carotid artery stenosis (>70%) and 6 individuals without stenosis. Seven different postprocessing methods were evaluated: first moment, ratio of area to peak, time to peak (TTP), relative TTP, arrival time, full-width at half-maximum, and deconvolution methods. Follow-up MR or CT images were used to determine the areas that evolved into infarcts, which served as the gold standard. Sensitivity and specificity of each transit time technique were calculated. RESULTS: Calculation methods with high sensitivity were the first moment (sensitivity, 74%), TTP (sensitivity, 77%), and deconvolution methods (sensitivity, 81% to 94%). Between the 2 groups with and without internal carotid artery stenosis, the specificity of most of the techniques was lower in the internal carotid artery stenosis group. The first moment and deconvolution methods maintained relatively high specificity even in the stenosis group. CONCLUSIONS: The calculation technique and presence of underlying vasculopathy have a direct impact on the results of PWI. The methods with high sensitivity even in the presence of steno-occlusive disease were the first moment and deconvolution methods with arterial input function derived from the peri-infarct arteries; the deconvolution method was the superior choice because of higher lesion conspicuity.

Acute Disease↗
PubMed1996

An amplitude-specific divergence in the pulsatile mode of growth hormone (GH) secretion underlies the gender difference in mean GH concentrations in men and premenopausal women.

Although many studies have discerned higher serum GH concentrations in women than in men, based on measurements of single random blood samples or integrated 24-h means, the neuroendocrine mechanisms that underlie such gender differences have not been defined. Such mechanisms might entail an increase in GH-secretory burst frequency, amplitude, or duration, heightened interpulse basal GH release, or a prolonged half-life of GH. These mechanisms can be distinguished by deconvolution analysis of appropriate GH time series. Earlier studies employed RIA or IRMA with sensitivities of 0.1-0.5 microgram/L, which result in frequently undetectable serum GH concentrations. To address these limitations, we undertook blood sampling at 10-min intervals for 24 h and applied a high-sensitivity immunofluorometric assay of GH (sensitivity 0.0115 microgram/L). Multiparameter deconvolution analysis was used to estimate specific features of GH secretion, while simultaneously calculating the half-life of endogenous GH. Eleven men and 11 premenopausal women from the same community were studied. Discrete peak detection by Cluster was employed as a complementary half-life-independent technique to assign variations in serum GH into pulsatile and basal fractions over 24 h. Cluster revealed significantly higher mean serum GH concentrations over 24 h in women (0.78 +/- 0.08 microgram/L) compared with in men (0.27 +/- 0.03 microgram/L, P < 0.00005). Women exhibited significantly higher maximal serum GH concentration peak values than men (2.08 +/- 0.34 microgram/L in women, 0.67 +/- 0.11 microgram/L in men, P = 0.0008), which could be, in turn, attributed to a significantly increased incremental serum GH peak amplitude (1.85 +/- 0.33 microgram/L in women vs. 0.60 +/- 0.10 microgram/L in men, P = 0.0021) and a longer peak duration (114 +/- 8 min in women, 86 +/- 4 min in men, P = 0.008). The mean area under the serum GH concentration peak was significantly (3-fold) higher in women than in men (98 +/- 17 micrograms/L.min in women, 34 +/- 8 micrograms/L.min in men, P = 0.0046). Serum GH peak frequency was similar in women (9.7 +/- 0.8 peak/24 h) and men (10.7 +/- 1.1 peak/24 h, P = NS). The mechanisms underlying the increase in serum GH concentration pulse amplitude, duration, and area were investigated further by deconvolution analysis. Deconvolution analysis disclosed equivalent secretory pulse frequencies in women and men (13 +/- 0.9 bursts/day in women, 10.5 +/- 1.3 bursts/day in men,P = NS), and statistically indistinguishable mean interburst intervals of 106 +/- 8 min in women and 150 +/- 26 min in men (P = NS). GH-secretory burst mass was significantly higher in women by approximately 2.4-fold (P = 0.0013) compared with in men, which was attributed to a greater burst amplitude. Only low levels of basal GH release were inferred in women (5%) and men (9%), which did not differ significantly between genders. Moreover, the calculated half-life of endogenous GH was no different in women compared with in men: 15.8 +/- 0.7 min vs. 17.1 +/- 0.8 min, respectively (P = NS). The calculated daily secretion rate was 3-fold higher in women (47 +/- 4.8 micrograms/L.24 h) than in men (15 +/- 1.8 micrograms/L.24 h) (P < 0.001). In summary, discrete peak-detection analysis of serum GH concentration profiles collected at 10-min intervals over 24 h in men and premenopausal women discloses significantly different mean serum GH concentrations that are accounted for by higher maximal and incremental serum GH peak amplitudes. Deconvolution analysis demonstrated that the mechanism supporting the amplitude-specific difference in women was an augmentation of the GH-secretory burst mass caused by a higher GH-secretory burst amplitude. These gender differences were highly specific because the frequency of detectable GH-secretory bursts, the calculated endogenous half-life, and the estimated basal GH release were no different in women than in men.

Adolescent↗
PubMed2023

GBMdeconvoluteR accurately infers proportions of neoplastic and immune cell populations from bulk glioblastoma transcriptomics data.

BACKGROUND: Characterizing and quantifying cell types within glioblastoma (GBM) tumors at scale will facilitate a better understanding of the association between the cellular landscape and tumor phenotypes or clinical correlates. We aimed to develop a tool that deconvolutes immune and neoplastic cells within the GBM tumor microenvironment from bulk RNA sequencing data. METHODS: We developed an IDH wild-type (IDHwt) GBM-specific single immune cell reference consisting of B cells, T-cells, NK-cells, microglia, tumor associated macrophages, monocytes, mast and DC cells. We used this alongside an existing neoplastic single cell-type reference for astrocyte-like, oligodendrocyte- and neuronal progenitor-like and mesenchymal GBM cancer cells to create both marker and gene signature matrix-based deconvolution tools. We applied single-cell resolution imaging mass cytometry (IMC) to ten IDHwt GBM samples, five paired primary and recurrent tumors, to determine which deconvolution approach performed best. RESULTS: Marker-based deconvolution using GBM-tissue specific markers was most accurate for both immune cells and cancer cells, so we packaged this approach as GBMdeconvoluteR. We applied GBMdeconvoluteR to bulk GBM RNAseq data from The Cancer Genome Atlas and recapitulated recent findings from multi-omics single cell studies with regards associations between mesenchymal GBM cancer cells and both lymphoid and myeloid cells. Furthermore, we expanded upon this to show that these associations are stronger in patients with worse prognosis. CONCLUSIONS: GBMdeconvoluteR accurately quantifies immune and neoplastic cell proportions in IDHwt GBM bulk RNA sequencing data and is accessible here: https://gbmdeconvoluter.leeds.ac.uk.

Humans↗
PubMed2001

In vitro-in vivo correlation (IVIVC) models for metformin after administration of modified-release (MR) oral dosage forms to healthy human volunteers.

The objective of the current study was to develop and evaluate the internal predictability for level C and A in vitro-in vivo correlation (IVIVC) models for prototype modified-release (MR) dosage forms of metformin. In vitro dissolution data for metformin were collected for 22 h using a USP II (paddle) method. In vivo plasma concentration data were obtained from 8 healthy volunteers after administration of immediate-release (IR) and MR dosage forms of metformin. Linear level C IVIVC models were developed using dissolution data at 2.0 and 4.0 h and in vitro mean dissolution time (MDT). A deconvolution-based level A model was attempted through a correlation of percent in vivo input obtained through deconvolution and percent in vitro dissolution obtained experimentally. Further, basic and extended convolution level A IVIVC models were attempted for metformin. Internal predictability for the IVIVC models was assessed by comparing observed and predicted values for C(max) and AUC(INF). The results suggest that highly predictive level C models with prediction errors (%PE) of <5% could be developed. Mean percent in vivo input for metformin was incomplete from all formulations and did not exceed 35% of dose. The deconvolution-based level A models for all MR formulations were curvilinear. However, a unique IVIVC model applicable to all MR formulations could not be developed using the deconvolution approach. The basic convolution level A model, which used in vitro dissolution as the in vivo input, had %PE values as high as 103%. Using an extended convolution approach, which modeled the absorption of metformin using a Hill function, a level A IVIVC model with %PE as low as 11% was developed. In conclusion, the current work indicates that level C and A IVIVC models with good internal predictability may be developed for a permeability- and absorption window-limited drug such as metformin.

Administration, Oral↗
PubMed1996

High resolution measurement of cerebral blood flow using intravascular tracer bolus passages. Part I: Mathematical approach and statistical analysis.

The authors review the theoretical basis of determination of cerebral blood flow (CBF) using dynamic measurements of nondiffusible contrast agents, and demonstrate how parametric and nonparametric deconvolution techniques can be modified for the special requirements of CBF determination using dynamic MRI. Using Monte Carlo modeling, the use of simple, analytical residue models is shown to introduce large errors in flow estimates when actual, underlying vascular characteristics are not sufficiently described by the chosen function. The determination of the shape of the residue function on a regional basis is shown to be possible only at high signal-to-noise ratio. Comparison of several nonparametric deconvolution techniques showed that a nonparametric deconvolution technique (singular value decomposition) allows estimation of flow relatively independent of underlying vascular structure and volume even at low signal-to-noise ratio associated with pixel-by-pixel deconvolution.

Cerebrovascular Circulation↗
PubMed1997

Non-invasive assessment of technetium-99m albumin transit time distribution in the pulmonary circulation by first-pass angiocardiography.

This study describes a non-invasive method for assessment of the lung transit time distribution of a tracer, using first-pass technetium-99m albumin angiocardiography and a model-free method of deconvolution. Ten patients received a first injection of 1 MBq kg-1 in the external jugular vein to position a gamma camera in the left anterior oblique position and two additional injections (5 MBq kg-1) to record first-pass angiocardiographic data. Right and left ventricular time-activity curves were derived from regions of interest every 0.5 s over a 1-min period. The left ventricular curve was deconvoluted by the right ventricular curve to obtain the lung transport function. The deconvolution procedure was based on a modified version of the Kalman filtering technique. The procedure was repeated at an interval of 30 min in eight patients. Two patients were re-examined up to 2 years later. Skewness, kurtosis and relative dispersion of the distributions did not change over time. We also found that the distribution, once normalized by its first moment, was independent of isolated changes in heart rate or cardiac output. Comparison of curve shapes at an interval of 30 min by point by point analysis demonstrated the reproducibility of the technique. We conclude that computation of the pulmonary transit time distribution of 99mTc-albumin from a standard angiocardiography procedure by model-free deconvolution is reliable and reproducible over time. We suggest that it may be a valuable tool for the non-invasive follow-up of the pulmonary circulation.

Adult↗
PubMed1980

Mathematical basis and generalization of the Loo-Riegelman method for the determination of in vivo drug absorption.

A general numerical deconvolution method is derived for the determination of in vivo drug input functions. The derivation is based on linear interpolation of observed drug concentrations and deconvolution of the resulting trapezoidal function. Derived in vivo input functions are discontinuous. A general expression for the cumulative drug input is also derived. The latter expression is a generalization of the Loo-Riegelman equations. This deconvolution method give similar results to the "point-area" deconvolution method when deriving in vivo drug input functions.

Intestinal Absorption↗
PubMed2003

X-ray photoelectron spectroscopy for detection of the different Si-O bonding states of silicon.

X-ray photoelectron spectroscopy (XPS) was used to detect the bonding between a silica particle surface and attached silanes. In addition to the commonly recorded Si 2p spectrum, the Si 1 s level is also accessible when monochromatic Ag Lalpha X-rays are applied. Furthermore, the spectrum of the Si 1 s level shows a fine structure. After spectrum deconvolution, we assigned the fitted spectral peaks to Si-C bonds of the silanes and to the Si-O bonds of the silica network. The recorded Si 1 s spectra were deconvoluted into peaks originating from Si-C bonds and the Si-O-Si silica network. To check the results of spectrum deconvolution, several differently functionalized silanes containing stoichiometric amounts of heteroatoms were applied for silica surface modification. We conclude that spectra deconvolution of the Si 1 s signal is an appropriate means for quantification of surface attached silane molecules.

Journal Article↗
PubMed1988

Multiwavelength method for measuring concentration of free cytosolic calcium using the fluorescent probe indo-1.

It is assumed that the spectra of fluorescent probes indo-1 and fura-2 in the cytoplasm are linear combinations of the spectra of calcium-bound and free probes with weight factors proportional to the concentrations of these forms. When the concentration of calcium is measured by the dual-wavelength method, the above assumption is employed without testing. A multiwavelength method for measuring free cytosolic calcium concentration is described in the present study. The method is based on the registration of the fluorescence spectra of the probe with an optical multichannel analyzer and deconvolution of the spectra into components, corresponding to free and bound forms of the probe. A mismatch is also calculated to allow estimation of deconvolution accuracy. It was found that the spectra, recorded in aqueous calibration solution with varying calcium concentrations, can be deconvoluted into components, obtained both in the absence of calcium and at its saturating concentration. When the spectrum of the probe in the cytoplasm is deconvoluted into the same components the mismatch is higher. When aqueous calibration is used, the cytosolic calcium concentration determined by the dual-wavelength method is dependent considerably on the selected wavelengths. Our data indicate that this phenomenon may be associated with the lower polarity of cytoplasm compared to the aqueous calibration solution. Addition of either ethanol or glycerol into the calibration medium results in a considerable decrease in the mismatch. The optimal concentration of ethanol is 22-32%, and depends on the type and condition of cells tested. It is shown that the use of calibration spectra obtained in aqueous solutions leads to considerable overestimation of cytosolic calcium concentration.

Calcium↗
PubMed1994

Pulsatile velocity distribution and wall shear rate measurement using pulsed Doppler ultrasound.

Instantaneous pulsatile velocity profiles were measured in a cylindrical tube using a 20 MHz pulsed Doppler ultrasound system. The spatial resolution of the device was improved with deconvolution using a procedure which employed frequency-domain windowing to suppress high-frequency noise. After deconvolution both the instantaneous velocity profiles and flow waveforms were compared with established theoretical predictions and good agreement was obtained. The average error in a velocity measurement was 7.9 +/- 0.9%, and the average error in the flow rate was 4.7 +/- 1.7%. The wall shear rate was determined from the gradient of the velocity profile both before and after deconvolution. The results were compared to the theoretical value of wall shear rate to quantify the accuracy of the technique under pulsatile flow conditions. Although the velocity profiles agreed well with theory, the wall shear rate was obtained less accurately. The average error in the mean wall shear rate and peak-to-peak wall shear rate was 28 +/- 7% and 11 +/- 3%, respectively. However, some of this discrepancy, was attributed to the method of evaluation. In all cases deconvolution significantly improved the accuracy of the wall shear rate determination.

Blood Flow Velocity↗