Photo of Johannes Johansson

Johannes Johansson

Associate professor, Docent

I work with optical techniques for microvascular blood flow measurements such as diffuse correlation spectroscopy and laser speckle imaging. I develop these to obtain 3D measurements with depth resolution in contrast to current 2D imaging.

Laser Speckle Techniques, Deep Brain Stimulation & the Finite Element Method

Partial thickness burn wounds are very painful burn wounds where the dermal layer of the skin partially is dead and coagulated. Depending on the depth and area of the burn wound, it may heal on its own or it may need surgical removal of skin and skin transplantation. This is something that is desirable to diagnose as fast as possible for optimal treatment.

In small children, measurement of the skin blood flow with laser speckle contrast imaging (LSCI) is useful for the diagnosis as their dermis is very thin. However, LSCI has limited measurement depth and only gives a two-dimensional image of the blood flow. I work on developing laser speckle techniques to reach deeper into the tissue and to obtain depth-resolved measurements with the aim of assessing the coagulation depth and give fast burn wound diagnosis also in adults with thicker skin. 

In certain neurological conditions, such as Parkinson’s disease, there is overactivity in central areas of the brain that fine-tunes the movements of the body. This can result in symptoms such as tremor and rigidity in the patient. These symptoms can be reduced greatly by destroying or jamming a small part of the overactive area. I have studied technical methods for this such as radio frequency (RF) ablation, where a temperature-controlled high frequency current is used to thermally coagulate tissue, and deep brain stimulation (DBS), where a chronically implanted electrode is used to jam the pathologic activity. Exactly how DBS works is not known today, and I have used simulations with the finite element method (FEM) and axon simulations in order to estimate how DBS works and how it should be analyzed to correlate affected brain structures with clinical patient outcomes.

I have previously been a postdoc at ICFO – The Institute for Photonic Sciences in Spain where I studied effects on blood volume, oxygen saturation and flow with optical techniques. I am also research coordinator for the e-Health area of strength.         

 

Research interests

  • Development of laser speckle techniques for measurements of blood flow in burn wounds and compartment syndrome.
  • Finite element method (FEM) simulations of radio frequency (RF) ablation in the brain, especially modeling and studying impact blood flow and convection in cerebrospinal fluid.
  • FEM simulations of deep brain stimulation (DBS)
  • Experimental studies on RF ablation in the brain.
  • Clinical study of electric impedance and reflected light intensity in the human brain for guidance during implantation of deep brain stimulation electrodes.
  • Monte Carlo simulations for short fiber distance light transport in the brain.
  • Development of light transport models for invasive spectroscopy in the brain.
  • Clinical study of chromophore content (e.g. blood volume and oxygenation, lipofuscin and mitochondrial cytochromes) in the brain along trajectories for deep brain stimulation electrodes. 
  • Scanning system for simultaneous intermediate fibre distance diffuse optical spectroscopy (DOS) and diffuse correlation spectroscopy (DCS) for measurement of blood flow, volume and oxygenation.
  • Murine in vivo study of effects on blood flow, volume and oxygenation from antiangiogenic therapy in renal cell carcinoma.
  • Clinical study of blood flow, volume and oxygen saturation in the thyroid using DCS and time-resolved spectroscopy.
  • Laser ablation of renal cell carcinoma

Publications

2022

2021

Research

Coworkers

Organisation