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Arif M, Groen J, Boevé ER, de Korte CL, Idzenga T, van Mastrigt R. Noninvasive Diagnosis of Bladder Outlet Obstruction in Patients with Lower Urinary Tract Symptoms Using Ultrasound Decorrelation Analysis. J Urol 2016; 196:490-7. [DOI: 10.1016/j.juro.2016.02.2966] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Muhammad Arif
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Jan Groen
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Egbert R. Boevé
- Department of Urology, Sint Franciscus Gasthuis and Havenziekenhuis Rotterdam, Rotterdam, The Netherlands
| | - Chris L. de Korte
- Medical UltraSound Imaging Center, Department of Radiology and Nuclear Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Tim Idzenga
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
- Department of Urology, Academic Medical Center, Amsterdam, The Netherlands
| | - Ron van Mastrigt
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
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Arif M, Idzenga T, van Mastrigt R, de Korte CL. Diagnosing Bladder Outlet Obstruction Using Non-invasive Decorrelation-Based Ultrasound Imaging: A Feasibility Study in Healthy Male Volunteers. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:3163-3171. [PMID: 26403699 DOI: 10.1016/j.ultrasmedbio.2015.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/15/2015] [Accepted: 08/04/2015] [Indexed: 06/05/2023]
Abstract
A feasibility study on the applicability of an ultrasound decorrelation method to urinary flow imaging was carried out in 20 healthy male volunteers, to provide a basis for a non-invasive approach to diagnose bladder outlet obstruction. Each volunteer voided five times in a flow meter in standing position. During each voiding, ultrasound radiofrequency frames were acquired transperineally at different flow rates. The results indicated that the decrease in correlation (decorrelation) of ultrasound radiofrequency signals had no unique relation with flow rate, but decreased distinctively with urinary flow velocity. In most of the healthy volunteers, the decorrelation was small because of the low flow velocity. However, because of the different flow velocities in volunteers, the variation in slope between volunteers was statistically significant. Therefore, it is probably possible to use the decorrelation method to differentiate between healthy persons and patients with obstruction.
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Affiliation(s)
- Muhammad Arif
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands.
| | - Tim Idzenga
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Ron van Mastrigt
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Chris L de Korte
- Medical UltraSound Imaging Center (MUSIC), Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Arif M, Idzenga T, de Korte CL, van Mastrigt R. Development of a Noninvasive Method to Diagnose Bladder Outlet Obstruction Based on Decorrelation of Sequential Ultrasound Images. Urology 2015; 85:648-52. [DOI: 10.1016/j.urology.2014.11.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/19/2014] [Accepted: 11/25/2014] [Indexed: 11/24/2022]
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Arif M, Idzenga T, de Korte CL, van Mastrigt R. Dependence of ultrasound decorrelation on urine scatter particle concentration for a non-invasive diagnosis of bladder outlet obstruction. Neurourol Urodyn 2014; 34:781-6. [PMID: 25251074 DOI: 10.1002/nau.22666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/14/2014] [Indexed: 11/07/2022]
Abstract
AIMS To develop a non-invasive method to diagnose Bladder Outlet Obstruction (BOO) based on decorrelation of subsequently acquired UltraSound (US) data of urinary flow, we studied the influence of scatter particle concentration on the decorrelation process in urethra models using both aqueous solutions of scattering particles and urine samples. METHODS A tissue mimicking urethra model made from PolyVinyl Alcohol (PVA) solution was infused with seven aqueous solutions containing different particle concentrations at a constant flow rate value of 10 ml/sec. The average correlation coefficients between subsequent US images were calculated and plotted as a function of particle concentration. This procedure was also applied to stepwise diluted urine samples from nine healthy volunteers. An inversely exponential curve was fitted to the experimental data to estimate the scatter particle concentration in the urine samples. RESULTS The average correlation values between subsequent US images increased with the particle concentration. The morning urine samples contained an appropriate number of scattering particles to make clinical application of the decorrelation method possible. The fitted correlation curves made an estimation of urine particle concentration possible. CONCLUSION The results of this study show that morning urine is suitable for US decorrelation without correcting for differences in particle concentration.
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Affiliation(s)
- Muhammad Arif
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Tim Idzenga
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands.,MUSIC Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Chris L de Korte
- MUSIC Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Ron van Mastrigt
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
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Arif M, Idzenga T, van Mastrigt R, de Korte CL. Estimation of urinary flow velocity in models of obstructed and unobstructed urethras by decorrelation of ultrasound radiofrequency signals. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:938-946. [PMID: 24412180 DOI: 10.1016/j.ultrasmedbio.2013.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 10/02/2013] [Accepted: 11/05/2013] [Indexed: 06/03/2023]
Abstract
The feasibility of estimating urinary flow velocity from the decorrelation of radiofrequency (RF) signals was investigated in soft tissue-mimicking models of obstructed and unobstructed urethras. The decorrelation was studied in the near field, focal zone and far field of the ultrasound beam. Furthermore, the effect of beam width was investigated. The results of this study suggest that it is feasible to estimate flow velocity in models of the urethra by quantifying the decorrelation of RF ultrasound signals. The decorrelation slope increased more rapidly and more linearly with increasing velocity in the focal zone than in the near and far field. A preliminary example of an in vivo measurement in a healthy volunteer illustrated that this method has potential for clinical use in the future.
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Affiliation(s)
- Muhammad Arif
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands.
| | - Tim Idzenga
- Department of Radiology, Medical Ultrasound Imaging Center, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Ron van Mastrigt
- Department of Urology, Sector Furore, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Chris L de Korte
- Department of Radiology, Medical Ultrasound Imaging Center, Radboud University Medical Centre, Nijmegen, The Netherlands
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de Ana FJ, O'Donnell M. Quantitative real-time blood flow estimation with intravascular ultrasound in the presence of in-plane flow. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2005; 52:1952-61. [PMID: 16422407 DOI: 10.1109/tuffc.2005.1561664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Previously, we showed a source of error in blood flow estimation introduced by in-plane flow using a slow-time finite-impulse response (FIR) filter-bank method measuring blood flow through the image plane of an intravascular ultrasound (IVUS) catheter array. There is a monotonic relationship between flow velocity and the normalized second moment of the slow-time spectrum when flow is orthogonal to the image plane of a side-looking catheter array. However, this relationship changes in the presence of in-plane flow, as slow-time spectra shift and spread with varying in-plane and out-of-plane components. These two effects increase the normalized spectral second moment, resulting in flow overestimates. However, by resampling the received signal with variable time delay from pulse to pulse (i.e., tilting the slow-time signals), the slow-time spectrum shifts back to direct current (DC), and the orthogonal estimation method can be used. We present a method to correct this overestimation and accurately estimate blood flow through the image plane in real time. Initially, the tilt delay needed to shift the slow-time spectrum back to DC at each point within the flow field is calculated. Knowing this tilt delay, a tilted slow-time signal is obtained for the velocity component normal to the image plane, and its spectrum is estimated using a filter-bank. That spectrum then is used to estimate the flow speed using a mapping function closely related to the monotonic relationship between the slow-time spectrum and flow speed observed for orthogonal flow. To accurately estimate flow angles, we modified the filter-bank algorithm, applying slow-time filter coefficients in a tilted arrangement and studying the slow-time spectral energy as a function of tilt. The slow-time spectral estimate is constructed with the tilted output of eight narrow, band-pass filters from a filter-bank. Independent simulations show that, for blood slowing at angles between +/-6 degrees and +/-15 degrees at a speed of 300 mm/s, flow velocity would be overestimated by as much as 38.79% and 249%, respectively, using the direct filter-bank approach. However, this error can be corrected using the modified method presented here, reducing the maximum overestimation error by a factor of 2.69 and 10.88 for those angles, respectively. Although the remaining error is not negligible, the volume flow rate, calculated by integrating the flow velocity over the entire vessel lumen, differs by only 3% or less from the true value over the angular range considered here. This represents an improvement of a factor of 40 over uncompensated estimates at maximum flow angles. Consequently, the modified real-time method can quantitatively measure flow in most IVUS applications in which the catheter's image plane is not precisely orthogonal to the flow direction.
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Affiliation(s)
- Francisco J de Ana
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
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Lupotti FA, Zimmer A, Daronat M, Foster FS, van Der Steen AFW, Cloutier G. Effects of aggregation of red cells and linear velocity gradients on the correlation-based method for quantitative IVUS blood flow at 20 MHz. ULTRASOUND IN MEDICINE & BIOLOGY 2004; 30:205-214. [PMID: 14998673 DOI: 10.1016/j.ultrasmedbio.2003.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2002] [Accepted: 10/09/2003] [Indexed: 05/24/2023]
Abstract
Recent computer simulations suggest that the presence of aggregates of red blood cells (RBCs), at random angles and lengths, does not affect the measurements of blood flow transverse to the ultrasound (US) beam direction using a correlation-based method and an intravascular (IV) US array catheter. However, in case of aggregates of RBCs aligned with the flow, measurements of simulated blood velocity are affected. Blood velocity gradients were also shown not to influence the correlation-based method for blood velocity estimation. The objective of this study was to quantify the influence of aggregates of RBCs and blood velocity gradients on the correlation-based method during in vitro experiments. For this purpose, measurements were performed on washed RBCs (no aggregation), normal human blood, and two types of diseased blood in which a lower or a higher level of aggregation was present. The decorrelation pattern of a circular US transducer as a function of transverse blood flow was studied using a Couette system. Changing the shear rate of the Couette system modified the aggregation level of RBCs and the velocity gradient. With the exception of the results at low shear rates and abnormally high aggregation levels, agreements were found between the autoconvolution of the acoustical beam (reference curve) and the radiofrequency (RF) decorrelation patterns. For the high shear rate present in coronary arteries, the correlation-based method for blood flow estimation should not be influenced by these phenomena.
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Affiliation(s)
- Fermín A Lupotti
- Experimental Echocardiography, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
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de Ana FJ, O'Donnell M. Blood flow estimation error with intravascular ultrasound due to in-plane component of flow. ULTRASONIC IMAGING 2003; 25:193-212. [PMID: 14870803 DOI: 10.1177/016173460302500306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Previously, we presented a real-time method to measure blood flow perpendicular to the image plane of an intravascular ultrasound (IVUS) imaging system using a slow-time FIR (finite impulse response) filter bank. Any in-plane flow introduces error in the flow measurement using the filter bank algorithm. Simulations show that for a flow angle of +/- 10 degrees and velocities between 200 mm/s and 300 mm/s, the energy within the lowest frequency band filter is 6.92 to 7.80 times higher than for perpendicular flow in the worst case. We present a variation of the FIR filter bank algorithm, applying filter coefficients in a tilted fashion to slow-time signals (i.e., combining slow-time and fast-time). An appropriate tilt, which depends on the flow angle and velocity, corrects for the increased energy under the frequency bands. In this case, the energy under the lowest frequency band filter for an angle of +/- 10 degrees and velocities ranging from 200 mm/s to 300 mm/s is 2.09 to 2.94 times higher than for perpendicular flow, yielding greater than a factor of three improvement in the worst case over the original slow-time method. Moreover, the average energy over the vessel determined with the appropriate tilt is within 2-3% of the true value.
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Affiliation(s)
- F J de Ana
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099, USA
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Lupotti FA, Mastik F, Carlier SG, de Korte CL, van der Giessen WJ, Serruys PW, van der Steen AFW. Quantitative IVUS blood flow: validation in vitro, in animals and in patients. ULTRASOUND IN MEDICINE & BIOLOGY 2003; 29:507-515. [PMID: 12749921 DOI: 10.1016/s0301-5629(02)00774-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In recent years, a new method to measure transverse blood flow based on the decorrelation of the radiofrequency (RF) signals of intravascular ultrasound (IVUS) rotating single-element scanners was introduced. We report here in vitro, animal and patient testing to evaluate the correlation-based method using an IVUS array catheter. A new correlation-based method to dynamically correct the correlation coefficients for noise is implemented. The decorrelation due to noise was estimated from the correlation coefficients from flowing blood obtained at increasing time lags. First, blood flow experiments were carried out with different catheters in a tissue-mimicking flow phantom with an inner diameter ranging from 3.0 to 5.0 mm. A calibrated electromagnetic flow meter (EMF, range: 0 to 250 cc/min) was used as a reference. Good linear relationships were found between the IVUS-derived flow and the calibrated EMF (all R(2)> 0.96). The catheter position within the flow phantom and the size of the ring-down were theoretically analyzed. These elements, and noise in the RF signals, have an important influence on the IVUS blood flow measurements reflected by the offset and the slope of the linear relationships. By placing the IVUS catheter outside the flow phantom, parabolic blood flow profiles were also measured. Second, IVUS blood flow measurements were performed in the carotid artery of two Yorkshire pigs, which showed linear relationships (all R(2)> 0.85) between the IVUS-derived flow and the calibrated EMF. Experimentally, the offset was lower than 3 mL/min and the slope was close to 1. Third, IVUS blood flow measurements were performed in coronary arteries in patients. Preliminary results for the coronary flow reserve (CFR = high flow/baseline flow) in patients using the decorrelation method of RF signals of an array IVUS scanner were comparable with CFR based on Doppler measurements.
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Affiliation(s)
- Fermín A Lupotti
- Interuniversity Cardiology Institute of the Netherlands (I.C.I.N.), Utrecht, The Netherlands
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Lupotti FA, De Korte CL, Mastik F, Van Der Steen AFW. Dynamic noise correction for IVUS quantitative volume blood flow: methods and numerical validation. ULTRASOUND IN MEDICINE & BIOLOGY 2002; 28:1053-1060. [PMID: 12217441 DOI: 10.1016/s0301-5629(02)00556-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In recent years, a new method to measure transverse blood flow based on the decorrelation of the radio-frequency (RF) signals, has been developed. Transverse blood flow estimation may be influenced by noise. In this paper, we investigated a new correlation-based method for noise correction. The decorrelation characteristics of transverse blood flow using an intravascular ultrasound (US) or IVUS array catheter were studied by means of computer modeling. Blood was simulated as a collection of randomly located point scatterers; moving this scattering medium transversely across the acoustical beam represented flow. Parabolic blood flow was simulated. Additive noise was added to the RF signals at a given signal-to-noise ratio (SNR). Next, a new method to dynamically estimate and suppress the decorrelation due to noise is presented. The decorrelation due to noise was estimated from the correlation coefficients from flowing blood obtained at increasing time lags. The correlation graphs are corrected for the decorrelation due to noise, leaving the decorrelation due to blood flow. The method shows promise to estimate and correct the correlation coefficients for noise.
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Affiliation(s)
- Fermin A Lupotti
- Experimental Echocardiography, Thoraxcentre, Erasmus University Rotterdam, Rotterdam, The Netherlands.
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