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Petri Välisuo

Bio: Petri Välisuo is an academic researcher from University of Vaasa. The author has contributed to research in topics: Computer science & Thermal energy. The author has an hindex of 6, co-authored 27 publications receiving 970 citations.

Papers
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Journal ArticleDOI
TL;DR: An overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used is given.
Abstract: The purpose of this paper is to give an overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used. Well over 200 papers describing this technique in clinical setting are reviewed. In addition to the surgical applications, other recent medical applications of ICG are briefly examined.

1,000 citations

Patent
19 Jun 2008
TL;DR: In this article, a change in the capacitance value of a sensor capacitor (CX) is detected by coupling it to a voltage supply (40), wherein said voltage supply is disconnected from a tank capacitor (c2) during said charging, transferring charge from a sensor to a tank during said charge transfer, and monitoring the voltage (VX) of the tank capacitor.
Abstract: Proximity of a person (BOD1) causes a change in the capacitance value of a sensor capacitor (CX) having a pair of capacitive plates (10a, 10b). Said change is detected by: - charging said sensor capacitor (CX) by coupling it to a voltage supply (40), wherein said voltage supply (40) is disconnected from a tank capacitor (C2) during said charging, - transferring charge from said sensor capacitor (CX) to a tank capacitor (C2), wherein said voltage supply (40) is disconnected from said tank capacitor (C2) during said charge transfer, - repeating said charging and charge transfer several times, - monitoring the voltage (VX) of said tank capacitor (C2), and - determining at least one value which depends on the rate of change of the voltage (VX) of said tank capacitor (C2). The capacitance of the capacitive sensor is typically low, typically in the order of 100 pF to 1 nF. The capacitance of the tank capacitor (C2) may be several orders of magnitude higher than the capacitance of the sensor capacitor (CX). The large tank capacitor (C2) acts as a part of a low-pass filter which effectively filters out signal noise.

42 citations

Journal ArticleDOI
01 Feb 2011-Burns
TL;DR: A new method developed for scar assessment combining standardized digital imaging (SDI) and spectral modelling (SpM) is introduced with this method, the estimated concentration changes (ECCs) of haemoglobin and melanin in the scar can be determined quantitatively.

37 citations

Journal ArticleDOI
TL;DR: The accuracy of the method is tested both computationally and experimentally using a Monte Carlo multilayer simulation model, and the data are measured from the palm of a hand during an Allen's test, which modulates the blood content of skin.
Abstract: The concentrations of blood and melanin in skin can be estimated based on the reflectance of light. Many models for this estimation have been built, such as Monte Carlo simulation, diffusion models, and the differential modified Beer-Lambert law. The optimization-based methods are too slow for chromophore mapping of high-resolution spectral images, and the differential modified Beer-Lambert is not often accurate enough. Optimal coefficients for the differential Beer-Lambert model are calculated by differentiating the diffusion model, optimized to the normal skin spectrum. The derivatives are then used in predicting the difference in chromophore concentrationsfromthedifferenceinabsorptionspectra.Theaccuracyofthemethodistestedbothcomputationally and experimentally using a Monte Carlo multilayer simulation model, and the data are measured from the palm of a hand during an Allen's test, which modulates the blood content of skin. The correlations of the given and predicted blood, melanin, and oxygen saturation levels are correspondingly r = 0.94, r = 0.99, and r = 0.73. The prediction of the concentrations for all pixels in a 1-megapixel image would take ∼20 min, which is orders of magnitude faster than the methods based on optimization during the prediction. C

29 citations

Journal ArticleDOI
TL;DR: Spectrocutometry is a feasible method for measuring scar hypertrophy and is shown to be more reliable than subjective rating in assessing linear surgical scars.
Abstract: Scar hypertrophy is a significant clinical problem involving both linear scars from elective surgery and scars caused by trauma or burns. The treatment of hypertrophic scars is often time consuming, and patients may need to be followed up for months or even years. The methods for reliable quantification of scar hypertrophy are at present unsatisfying. We have developed a new, objective method, Spectrocutometry, for documentation and quantification of scar hypertrophy. The instrument is based on standardized digital imaging and spectral modeling and calculates the estimated concentration change of hemoglobin and melanin from the entire scar and also provides standardized images for documentation. Three plastic surgeons have assessed 37 scars from melanoma surgery using Spectrocutometry, the Vancouver scar scale, and the patient and observer scar assessment scale. The intraclass correlation coefficient for the Vancouver scar scale and the patient and observer scar assessment scale was lower than required for reliable assessment (r=0.66 and 0.60, respectively). The intraclass correlation coefficient for Spectrocutometry was high (r=0.89 and 0.88). A Bayesian network analysis revealed a strong dependency between the estimated concentration change of hemoglobin and scar pain. Spectrocutometry is a feasible method for measuring scar hypertrophy. It is shown to be more reliable than subjective rating in assessing linear surgical scars.

28 citations


Cited by
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Journal ArticleDOI
TL;DR: An overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used is given.
Abstract: The purpose of this paper is to give an overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used. Well over 200 papers describing this technique in clinical setting are reviewed. In addition to the surgical applications, other recent medical applications of ICG are briefly examined.

1,000 citations

Book ChapterDOI
02 Mar 2001

984 citations

Journal ArticleDOI
TL;DR: PINPOINT is a safe and feasible tool for intraoperative assessment of tissue perfusion during colorectal resection and in patients in whom the anastomosis was revised based on inadequate perfusion with FA, according to a prospective, multicenter, open-label, clinical trial.
Abstract: Background Our primary objective was to demonstrate the utility and feasibility of the intraoperative assessment of colon and rectal perfusion using fluorescence angiography (FA) during left-sided colectomy and anterior resection. Anastomotic leak (AL) after colorectal resection increases morbidity, mortality, and, in cancer cases, recurrence rates. Inadequate perfusion may contribute to AL. The PINPOINT Endoscopic Fluorescence Imaging System allows for intraoperative assessment of anastomotic perfusion. Study Design This is a prospective, multicenter, open-label, clinical trial that assessed the feasibility and utility of FA for intraoperative perfusion assessment during left-sided colectomy and anterior resection at 11 centers in the United States. Results A total of 147 patients were enrolled, of whom 139 were eligible for analysis. Diverticulitis (44%), rectal cancer (25%), and colon cancer (21%) were the most prevalent indications for surgery. The mean level of anastomosis was 10 ± 4 cm from the anal verge. Splenic-flexure mobilization was performed in 81% and high ligation of the inferior mesenteric artery in 61.9% of patients. There was a 99% success rate for FA, and FA changed surgical plans in 11 (8%) patients, with the majority of changes occurring at the time of transection of the proximal margin (7%). Overall morbidity rates were 17%. The anastomotic leak rate was 1.4% (n = 2). There were no anastomotic leaks in the 11 patients who had a change in surgical plan based on intraoperative perfusion assessment with FA. Conclusions PINPOINT is a safe and feasible tool for intraoperative assessment of tissue perfusion during colorectal resection. There were no anastomotic leaks in patients in whom the anastomosis was revised based on inadequate perfusion with FA.

445 citations

Journal ArticleDOI
TL;DR: Indocyanine green, a clinically approved near-IR dye, exhibits a remarkable amount of SWIR emission, which enables state-of-the-art SWIR imaging with direct translation potential into clinical settings, and even outperforms other commercially available SWIR emitters.
Abstract: Fluorescence imaging is a method of real-time molecular tracking in vivo that has enabled many clinical technologies. Imaging in the shortwave IR (SWIR; 1,000-2,000 nm) promises higher contrast, sensitivity, and penetration depths compared with conventional visible and near-IR (NIR) fluorescence imaging. However, adoption of SWIR imaging in clinical settings has been limited, partially due to the absence of US Food and Drug Administration (FDA)-approved fluorophores with peak emission in the SWIR. Here, we show that commercially available NIR dyes, including the FDA-approved contrast agent indocyanine green (ICG), exhibit optical properties suitable for in vivo SWIR fluorescence imaging. Even though their emission spectra peak in the NIR, these dyes outperform commercial SWIR fluorophores and can be imaged in the SWIR, even beyond 1,500 nm. We show real-time fluorescence imaging using ICG at clinically relevant doses, including intravital microscopy, noninvasive imaging in blood and lymph vessels, and imaging of hepatobiliary clearance, and show increased contrast compared with NIR fluorescence imaging. Furthermore, we show tumor-targeted SWIR imaging with IRDye 800CW-labeled trastuzumab, an NIR dye being tested in multiple clinical trials. Our findings suggest that high-contrast SWIR fluorescence imaging can be implemented alongside existing imaging modalities by switching the detection of conventional NIR fluorescence systems from silicon-based NIR cameras to emerging indium gallium arsenide-based SWIR cameras. Using ICG in particular opens the possibility of translating SWIR fluorescence imaging to human clinical applications. Indeed, our findings suggest that emerging SWIR-fluorescent in vivo contrast agents should be benchmarked against the SWIR emission of ICG in blood.

434 citations

Journal ArticleDOI
TL;DR: In the experience, the ICG fluorescence imaging system seems to be simple, safe, and useful, and may well become a standard in the near future in view of its different diagnostic and oncological capabilities.
Abstract: Background Recently major developments in video imaging have been achieved: among these, the use of high definition and 3D imaging systems, and more recently indocyanine green (ICG) fluorescence imaging are emerging as major contributions to intraoperative decision making during surgical procedures. The aim of this study was to present our experience with different laparoscopic procedures using ICG fluorescence imaging.

367 citations