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Johansson, Johannes D
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Publikasjoner (10 av 42) Visa alla publikasjoner
Johansson, J., Portaluppi, D., Buttafava, M. & Villa, F. (2019). A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array. Journal of Biophotonics, Article ID UNSP e201900091.
Åpne denne publikasjonen i ny fane eller vindu >>A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array
2019 (engelsk)Inngår i: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, artikkel-id UNSP e201900091Artikkel i tidsskrift (Fagfellevurdert) Epub ahead of print
Abstract [en]

The autocorrelation of laser speckles from coherent near infrared light is used for noninvasive estimates of relative changes in blood perfusion in techniques such as laser Doppler flowmetry (LDF) and diffuse correlation spectroscopy (DCS). In this study, a 2D array of single photon avalanche diodes (SPADs) was used to combine the strengths of multiple detectors in LDF with high light sensitivity in DCS. The system was tested on milk phantoms with varying detector fiber diameter (200 and 600 μm), source‐detector fiber separation (4.6‐10.2 mm), fiber‐SPAD distance (2.5‐36.5 mm), contiguous measurement time per repetition for the autocorrelation (1‐33 ms) and temperature (15.6‐46.7°C). An in vivo blood occlusion test was also performed. The multipixel approach improved signal‐to‐noise ratio (SNR) and, in our setup, the use of a multimode detector fiber was beneficial for SNR. In conclusion, the multipixel system works, but improvements and further studies regarding, for example, the data acquisition and optimal settings are still 

Emneord
blood flow measurements, diffuse correlation spectroscopy, laser doppler flowmetry, SPAD array
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-159528 (URN)10.1002/jbio.201900091 (DOI)000478854100001 ()
Tilgjengelig fra: 2019-08-12 Laget: 2019-08-12 Sist oppdatert: 2019-08-19
Johansson, J., Portaluppi, D., Buttafava, M. & Villa, F. (2018). Development of a hybrid laser Doppler flowmetry and diffuse correlation spectroscopy system. In: : . Paper presented at Medicinteknikdagarna, Umeå, 9-10 oktober 2018.
Åpne denne publikasjonen i ny fane eller vindu >>Development of a hybrid laser Doppler flowmetry and diffuse correlation spectroscopy system
2018 (engelsk)Konferansepaper, Oral presentation with published abstract (Fagfellevurdert)
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-152444 (URN)
Konferanse
Medicinteknikdagarna, Umeå, 9-10 oktober 2018
Tilgjengelig fra: 2018-10-31 Laget: 2018-10-31 Sist oppdatert: 2018-10-31
Rejmstad, P., Johansson, J. D., Haj-Hosseini, N. & Wårdell, K. (2017). A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy. Journal of Biophotonics, 10(3), 446-455
Åpne denne publikasjonen i ny fane eller vindu >>A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy
2017 (engelsk)Inngår i: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, Vol. 10, nr 3, s. 446-455Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Continuous measurement of local brain oxygen saturation (SO2) can be used to monitor the status of brain trauma patients in the neurocritical care unit. Currently, micro-oxygen-electrodes are considered as the “gold standard” in measuring cerebral oxygen pressure (pO2), which is closely related to SO2 through the oxygen dissociation curve (ODC) of hemoglobin, but with the drawback of slow in response time. The present study suggests estimation of SO2 in brain tissue using diffuse reflectance spectroscopy (DRS) for finding an analytical relation between measured spectra and the SO2 for different blood concentrations. The P3 diffusion approximation is used to generate a set of spectra simulating brain tissue for various levels of blood concentrations in order to estimate SO2. The algorithm is evaluated on optical phantoms mimicking white brain matter (blood volume of 0.5–2%) where pO2 and temperature is controlled and on clinical data collected during brain surgery. The suggested method is capable of estimating the blood fraction and oxygen saturation changes from the spectroscopic signal and the hemoglobin absorption profile.

sted, utgiver, år, opplag, sider
Wiley-VCH Verlagsgesellschaft, 2017
Emneord
oxygenation, diffuse reflectance spectroscopy, hemoglobin, optical phantom, human brain
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-127362 (URN)10.1002/jbio.201500334 (DOI)000398216200012 ()27094015 (PubMedID)
Merknad

Funding agencies: Swedish Childhood Cancer Foundation; Swedish Research Council [621-2010-4216, 621-2013-6078]

Tilgjengelig fra: 2016-04-22 Laget: 2016-04-22 Sist oppdatert: 2017-04-20bibliografisk kontrollert
Wårdell, K., Johansson, J. & Alonso, F. (2017). Deep brain stimulation: software for patient-specific electric field simulations. In: : . Paper presented at World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017.
Åpne denne publikasjonen i ny fane eller vindu >>Deep brain stimulation: software for patient-specific electric field simulations
2017 (engelsk)Konferansepaper, Poster (with or without abstract) (Fagfellevurdert)
Abstract [en]

Introduction

The electric field (EF) around the active deep brain stimulation (DBS) contact is of interest for optimizing the therapeutic effect. We have previously developed a method for simulation and visualization of the EF. The aim of the project is to improve the software for quick and user friendly simulations.  

Methods

The ELMA software for brain model creation has been improved by adding quick ROI selection and transformation to an electrical conductivity map based on tissue classification through multiple slices of the preoperative MRI. These data are used as input for Comsol Multiphysics simulations of the EF. Two points along the position of the lead, as seen in the postoperative images, are used for correct placement in the brain model. Multiple DBS lead models are pre-programmed. The active contact and amplitude are user-selected.

Results

After a simulation the result is visualized with a user defined isolevel or isosurface superimposed on the patients preoperative MRI. An example is shown in Fig. 1. The 3389 lead is places in zona inserta (Zi) and contact 1 activated with 2 and 4 V respectively. An isolevel of 0.2 V/mm is used corresponding to a ~ 3-4 µm axon diameter when using a pulse length of 60 µs. More examples will be presented at the meeting.

Conclusion

The software for patient-specific simulations of EF around DBS electrodes has been improved for quicker simulations and more DBS leads. As a next step user friendly Apps will be implemented.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-139879 (URN)
Konferanse
World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017
Tilgjengelig fra: 2017-08-21 Laget: 2017-08-21 Sist oppdatert: 2017-08-21
Johansson, J., Akbarian-Tefaghi, L., Harith, A., Zrinzo, L., Limousin, P., Joyce, E., . . . Foltynie, T. (2017). Estimation of effective target area in the globus pallidus during deep brain stimulation for Tourette syndrome.. In: : . Paper presented at World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017.
Åpne denne publikasjonen i ny fane eller vindu >>Estimation of effective target area in the globus pallidus during deep brain stimulation for Tourette syndrome.
Vise andre…
2017 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-139858 (URN)
Konferanse
World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017
Tilgjengelig fra: 2017-08-17 Laget: 2017-08-17 Sist oppdatert: 2017-08-17
Göransson, N., Johansson, J., Alonso, F., Wårdell, K. & Zsigmond, P. (2017). Postoperative lead movement after deep brain stimulation surgery and changes of stimulation area. In: : . Paper presented at World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017. S. Karger
Åpne denne publikasjonen i ny fane eller vindu >>Postoperative lead movement after deep brain stimulation surgery and changes of stimulation area
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2017 (engelsk)Konferansepaper, Oral presentation with published abstract (Annet vitenskapelig)
Abstract [en]

Introduction

Lead movement after deep brain stimulation (DBS) may occur and influence the area of stimulation. The cause of the displacement is not fully understood. The aim of the study was to investigate differences in lead position between the day after surgery and approximately one month postoperatively and also simulate the electric field (EF) around the active contacts.

Methods

23 patients with movement disorders underwent DBS surgery (37 leads). CT at the two time points were co-fused respectively with the stereotactic images in Surgiplan. The coordinates (x, y, z) of the lead tips were compared between the two dates (paired t-test). 8 of these patients were selected for the EF simulation in Comsol Multiphysics.

Results

There was a significant discrepancy (mean ± s.d.) on the left lead: x (0.44 ± 0.72, p < 0.01), y (0.64 ± 0.54, p < 0.001), z (0.62 ± 0.71, p < 0.001).  On the right lead, corresponding values were: x (-0.11 ± 0.61, n.s.), y (0.71 ± 0.54, p < 0.001), z (0.49 ± 0.81, p < 0.05).  No correlation was found between bilateral (n =14) vs. unilateral DBS, gender (n = 17 male) and age < 60 years (n = 8).  The lead movement affected the EF spread (Fig. 1).

Conclusion

The left lead tip displayed a tendency to move lateral, anterior and inferior and the right a tendency to move anterior and inferior. Lead movement after DBS can be a factor to consider before starting the stimulation. The differences in the area of stimulation might affect clinical outcome.

sted, utgiver, år, opplag, sider
S. Karger, 2017
Serie
Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-139886 (URN)10.1159/000478281 (DOI)
Konferanse
World Society for Stereotactic and Functional Neurosurgery, 17th Quadrennial meeting, Berlin June 26-29, 2017
Tilgjengelig fra: 2017-08-21 Laget: 2017-08-21 Sist oppdatert: 2017-09-04
Akbarian-Tefaghi, L., Akram, H., Johansson, J., Zrinzo, L., Kefalopoulou, Z., Limousin, P., . . . Foltynie, T. (2017). Refining the Deep Brain Stimulation Target within the Limbic Globus Pallidus Internus for Tourette Syndrome. Stereotactic and Functional Neurosurgery, 95(4), 251-258
Åpne denne publikasjonen i ny fane eller vindu >>Refining the Deep Brain Stimulation Target within the Limbic Globus Pallidus Internus for Tourette Syndrome
Vise andre…
2017 (engelsk)Inngår i: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 95, nr 4, s. 251-258Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

BACKGROUND: Deep brain stimulation (DBS) in patients with severe, refractory Tourette syndrome (TS) has demonstrated promising but variable results thus far. The thalamus and anteromedial globus pallidus internus (amGPi) have been the most commonly stimulated sites within the cortico-striato thalamic circuit, but an optimal target is yet to be elucidated.

OBJECTIVES: This study of 15 patients with long-term amGPi DBS for severe TS investigated whether a specific anatomical site within the amGPi correlated with optimal clinical outcome for the measures of tics, obsessive compulsive behaviour (OCB), and mood.

METHODS: Validated clinical assessments were used to measure tics, OCB, quality of life, anxiety, and depression before DBS and at the latest follow-up (17-82 months). Electric field simulations were created for each patient using information on electrode location and individual stimulation parameters. A subsequent regression analysis correlated these patient-specific simulations to percentage changes in outcome measures in order to identify any significant voxels related to clinical improvement.

RESULTS: A region within the ventral limbic GPi, specifically on the medial medullary lamina in the pallidum at the level of the AC-PC, was significantly associated with improved tics but not mood or OCB outcome.

CONCLUSIONS: This study adds further support to the application of DBS in a tic-related network, though factors such as patient sample size and clinical heterogeneity remain as limitations and replication is required.

sted, utgiver, år, opplag, sider
S. Karger, 2017
Emneord
Deep brain stimulation, Globus pallidus internus, Modelling, Simulation, Tourette syndrome
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-139857 (URN)10.1159/000478273 (DOI)000410846200006 ()28787721 (PubMedID)2-s2.0-85027141067 (Scopus ID)
Merknad

Funding agencies: National Institute of Health Research (NIHR) Biomedical Research Centre at the UCL Institute of Neurology and UCLH-National Hospital for Neurology and Neurosurgery, London, UK; Swedish Research Council (Vetenskapsradet) [2016-03564]; Swedish Foundation fo

Tilgjengelig fra: 2017-08-17 Laget: 2017-08-17 Sist oppdatert: 2017-10-05bibliografisk kontrollert
Mireles, M., Johansson, J. D., Farzam, P., Martínez Lozano, M., Casanovas, O., Durduran, T. & Morales, J. (2016). A non-contact, small animal scanner based on diffuse optical spectroscopy and diffuse correlation spectroscopy. In: : . Paper presented at Optical Tomography and Spectroscopy 2016, Fort Lauderdale, Florida United States, 25–28 April 2016.
Åpne denne publikasjonen i ny fane eller vindu >>A non-contact, small animal scanner based on diffuse optical spectroscopy and diffuse correlation spectroscopy
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2016 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

A scanning system that combines broadband diffuse optical spectroscopy and diffuse correlation spectroscopy for non-contact, large field-of-view imaging of small animal models and humans is presented and demonstrated in vivo.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-129013 (URN)10.1364/OTS.2016.OTh1D.4 (DOI)978-1-943580-10-1 (ISBN)
Konferanse
Optical Tomography and Spectroscopy 2016, Fort Lauderdale, Florida United States, 25–28 April 2016
Tilgjengelig fra: 2016-06-08 Laget: 2016-06-08 Sist oppdatert: 2016-06-27
Lindner, C., Mora, M., Farzam, P., Squarcia, M., Johansson, J., Weigel, U. M., . . . Durduran, T. (2016). Diffuse Optical Characterization of the Healthy Human Thyroid Tissue and Two Pathological Case Studies.. PLoS ONE, 11(1)
Åpne denne publikasjonen i ny fane eller vindu >>Diffuse Optical Characterization of the Healthy Human Thyroid Tissue and Two Pathological Case Studies.
Vise andre…
2016 (engelsk)Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 1Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The in vivo optical and hemodynamic properties of the healthy (n = 22) and pathological (n = 2) human thyroid tissue were measured non-invasively using a custom time-resolved spectroscopy (TRS) and diffuse correlation spectroscopy (DCS) system. Medical ultrasound was used to guide the placement of the hand-held hybrid optical probe. TRS measured the absorption and reduced scattering coefficients (μa, μs') at three wavelengths (690, 785 and 830 nm) to derive total hemoglobin concentration (THC) and oxygen saturation (StO2). DCS measured the microvascular blood flow index (BFI). Their dependencies on physiological and clinical parameters and positions along the thyroid were investigated and compared to the surrounding sternocleidomastoid muscle. The THC in the thyroid ranged from 131.9 μM to 144.8 μM, showing a 25-44% increase compared to the surrounding sternocleidomastoid muscle tissue. The blood flow was significantly higher in the thyroid (BFIthyroid = 16.0 × 10-9 cm2/s) compared to the muscle (BFImuscle = 7.8 × 10-9 cm2/s), while StO2 showed a small (StO2, muscle = 63.8% to StO2, thyroid = 68.4%), yet significant difference. Two case studies with thyroid nodules underwent the same measurement protocol prior to thyroidectomy. Their THC and BFI reached values around 226.5 μM and 62.8 × 10-9 cm2/s respectively showing a clear contrast to the nodule-free thyroid tissue as well as the general population. The initial characterization of the healthy and pathologic human thyroid tissue lays the ground work for the future investigation on the use of diffuse optics in thyroid cancer screening.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-125651 (URN)10.1371/journal.pone.0147851 (DOI)26815533 (PubMedID)
Tilgjengelig fra: 2016-02-29 Laget: 2016-02-29 Sist oppdatert: 2017-11-30
Lindner, C., Mora Porta, M., Farzam, P., Squarcia, M., Johansson, J. D., Weigel, U., . . . Durduran, T. (2016). Diffuse optical characterization of the human thyroid. In: : . Paper presented at Cancer Imaging and Therapy 2016 Fort Lauderdale, Florida United States, 25–28 April 2016.
Åpne denne publikasjonen i ny fane eller vindu >>Diffuse optical characterization of the human thyroid
Vise andre…
2016 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

The human thyroid was measured by ultrasound-guided near-infrared time-resolved spectroscopy and diffuse correlation spectroscopy characterizing the healthy thyroid and nodules allowing us to envision applications in thyroid cancer screening.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-129010 (URN)10.1364/CANCER.2016.CTh4A.5 (DOI)978-1-943580-10-1 (ISBN)
Konferanse
Cancer Imaging and Therapy 2016 Fort Lauderdale, Florida United States, 25–28 April 2016
Tilgjengelig fra: 2016-06-08 Laget: 2016-06-08 Sist oppdatert: 2016-06-27
Organisasjoner