Activity: Brain imaging techniques

Brain imaging Techniques

Pet Scan

MRI

FMRI

Positron Emission Tomography (PET)

Main Characteristics

Strengths and limitations

How it works

Example study

sources

Back

Main Characteristics (PET)

PET has the following characteristics: -It is able to form metabolic imge and can follow metabolic processes with the imaging. -PET uses radiotracers, which help by assesing brain activity and can identify specific affected regions. -It is a non-invasive method. -It helps to identify various diseases in a timely manner. -It is useful for psychiatric analysis and study. Department of Neurosurgery and Cylotron Research Center. [Photograph of a PET scan using-15-O-labeled-O-2-and-CO-inhalation-and-H-2].(2007.). Iwate Medical University, Morioka, Iwate. https://www.researchgate.net/figure/Brain-positron-emission-tomography-scans-using-15-O-labeled-O-2-and-CO-inhalation-and-H-2_fig3_6424022

Return

How it works

PET follows this process in order to function: -Frirst, a radiotracer is injected to the patient and makes the brain respond to it. -Then, the emitted gama rays are detected by the PET scanner and the data is collected. -Lastly, the data detected by the PET is reconstructed so the radiotracer distribution is made into images and later analyzed. [Photograph of a PET scanner]. (n.d.).https://thancguide.org/cancer-basics/diagnosis/imaging/pet-scan/

Back

Strengths and Limitations

PET imaging strengths: -It is useful for early diagnosis overall. -It provides quantitative data based on the metabolic processes. This means that this study is useful to measure in numbers the interactions studied. -The PET results include both imagery and quantitative data, which might make a diagnosis and analysis easier and more complete. PET imaging limitations: -PET imaging uses radioactive materials to function, which might lead to negatives regarding the subject's wellbeing. -PET is expensive, which makes it less accesible as a brain imaging technique. -Once compared to other techniques, PET has a lower spatial resolution. -It is time consuming, this because it is necessary to wait for the tracer to be distributed properly.

Back

Example Study

FDG PET in the Evaluation of Parkinson's Disease

A study conducted in 2010 by the researchers Kathleen L Poston and David Eidelberg Aim: Proving the effectiveness of PET scans to detect Parkinson’s disease and other similar ailments (Eidelberg, D., Poston, L., K. 2010). Procedure: Method: They selected 34 patients which presented early symptoms of Parkinson's disease to consequently use a PET scan in each one of them, this process lasted for 2 years with patients being scanned every seven weeks. Results: Researchers found this method of brain mapping not only useful for the investigation but also they learned that it could be used to identify multiple disease-specific patterns in other parkinsonian syndromes, such as multiple system atrophy and progressive supranuclear palsy. Thus discovering that this method of brain scanning had a lot more potential that what they initially considered. Conclusions: PET is useful to identify Parkinson's disease and similar ailments that are related to the brain function.

Back

Sources

Return

Eidelberg, D., Poston, L., K.(2010).FDG PET in the Evaluation of Parkinson's Disease. PET Clin, Volume 1, issue 5., pp55-64. 10.1016/j.cpet.2009.12.004 OpenAI. (2023). ChatGPT (Sept 24 version) [Large language model]. https://chat.openai.com/chat Sources cited by ChatGPT: Decazes, P. et. al. (2021). Trimodality PET/CT/MRI and Radiotherapy: A Mini-Review. Frontiers. https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2020.614008/full Galldiks, N. (2024). Challenges, limitations, and pitfalls of PET and advanced MRI in patients with brain tumors: A report of the PET/RANO group. Society for NeuroOncology. https://doi.org/10.1093/neuonc/noae049 Hicks, R. J. (2004). Principles and Practice of Positron Emission Tomography. Journal of Nuclear Medicine, 45(11), 1973. http://jnm.snmjournals.org/content/45/11/1973.abstract Politis, M., Piccini, P. Positron emission tomography imaging in neurological disorders. J Neurol 259, 1769–1780 (2012). https://doi.org/10.1007/s00415-012-6428-3 Slough, C. et. al. (2016). Clinical Positron Emission Tomography (PET)Neuroimaging: Advantages and Limitations as a Diagnostic Tool. J Neuropsychiatry Clin. Neurosci. 28,2. https://psychiatryonline.org/doi/pdf/10.1176/appi.neuropsych.16030044 Xie, L. J., Zhao, J. H., Li, Y. & Bai, J. (2024) PET brain imaging in neurological disorders. Phys. Life Rev. 49, 100–111 .https://doi.org/10.1016/j.plrev.2024.03.007

Magnetic Resonance Imaging (MRI)

Main Characteristics

Strengths and limitations

How it works

Example study

Sources

Back

Main Characteristics

MRI has the following characteristics:

-Forms and image of the brain through frequencies.-Uses powerful magnets to produce a strong magnetic field. -Metal objects cannot be close to the machine. -It is a non-invasive method. -It is helpful to identify physical ailments such as tumors or inflamation.

[Photograph of an MRI scan of a 20 year old female]. (n.d.). https://radiopaedia.org/cases/normal-brain-mri-6

Return

How it works

MRI follows this process in order of function: - Firstly, the patient must retrieve from themselves any metallic objects, including piercings and watches, or alert the doctors in case they have some type of implant or device like pacemakers - Secondly, the patient must lay themselves in the bed-like surface in front of the machine and await for the doctor´s instructions - Thirdly, the machine will move forward the patient until it's completely inside of it and then it will start to activate its magnets, a process which is completely innocuous for the patient, taking pictures to be analyzed in the process.

Return

[Photogrph of Aslaam Alladina an MRI supervisor at Burnaby Hospital]. (2009). Burnaby Hospital Fundation. https://www.bhfoundation.ca/why-give/inspirational-stories/working-with-a-super-magnet-mri/

Strengths and Limitations

Magnetic resonance imaging strengths: -It is useful for building detailed images of the brain thanks to the contrast and spatial resolution. -It is generally safer to use because it does not make use of radiation. -It is a versatile tool and can include various types of results. Magnetic resonance imaging limitations: -It might be uncomfortable for some patients because of the enclosed nature of the study. -It cannot be used if the patient has metallic implants. -It has a lower sensibility, which means that it might not detect small abnormalities. -Generates mostly qualitative data, which might result detrimental for correctly determining the affection of the patient

Return

Example Study

Brain development during childhood and adolescence: a longitudinal MRI study

A study conducted in 1999 by Jay. N. Giedd and the rest of his team. Aim: Proving if a relationship between the increase in age and a decrease in the amount of gray matter in one individual’s brain existed. Method: Researchers were looking more specifically at the ages of 4-20 years. They recruited people in those year spans, many of whom were preadolescents. And they used the MRI to determine the variations in sizes of the amount of dark matter in each of them by comparing the results with each other. In the end, the study did confirm a linear increase in white matter. Results: The analysis effectuated in the patients' gray matter showed nonlinear changes in it. This showed that an increase or decrease in the amount of gray matter in a person is not directly proportional to age. Conclusion: According to the study, gray matter is independent from the age of the patient.

Return

Sources

-Blair, S.(2021). WHAT IS A VOLUMETRIC ANALYSIS OF THE BRAIN?. Brain injury law. https://www.braininjurylawofseattle.com/what-is-a-volumetric-analysis-of-the-brain/ -Clerval Clinic.(2022). Brain MRI. Clerval Clinic. https:E//my.clevelandclinic.org/health/diagnostics/22966-brain-mri -Giedd, N.,J. et al.(1999). Brain development during childhood and adolescence: a longitudinal MRI study. Nature neuroscience, Vol 2., pp. 861-863. -Health direct.(N/D). MRI scan. Health direct. https://www.healthdirect.gov.au/magnetic-resonance-imaging-mri#:~:text=An%20MRI%20is%20used%20to,ray%20radiation%2C%20and%20is%20painless. -FDA.(2024).Benefits and Risks.Food and drug administration.https://www.fda.gov/radiation-emitting-products/mri-magnetic-resonance-imaging/benefits-and-risks Resources cited by ChatGPT: -Tamangani, J. (2016). Neuroimaging.Australian Family Physician. 45-11. https://www.racgp.org.au/afp/2016/november/neuroimaging/ -Baltes, C., Mueggler, T., Rudin, M. (2014). Structural and Functional Magnetic Resonance Imaging. In: Stolerman, I., Price, L. (eds) Encyclopedia of Psychopharmacology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27772-6_298-2 -Das, M. (2024). Neuroimaging Techniques and What a Brain Image Can Tell Us. Technology Networks. https://www.technologynetworks.com/neuroscience/articles/neuroimaging-techniques-and-what-a-brain-image-can-tell-us-363422

Return

Functional Magnetic Resonance Imaging (fMRI)

Main Characteristics

Strengths and limitations

How it works

Example study

Sources

Back

Main Characteristics

FMRI scans have the following characteristics :- Its capable of detecting and creating images from the blood flow and oxygenation level in the brain. - It is a non-invasive procedure. - Mainly helps in detecting which areas of the brain are affected by mental diseases. - Involves the participation of the patient in simple activities to better locate which parts of the brain do certain functions

[Photograph of a person taking an FMRI scan with personnel besides him]. (n.d.).University of Oxford. https://www.ndcn.ox.ac.uk/divisions/fmrib/what-is-fmri/introduction-to-fmri

Return

How it works

FMRI follows this process in order of funtion: - First, the patient will not consume caffeine for at least a day before the study and certain types of medicines as well, since they could end up affecting the results of an FMRI. - Secondly, the person should remove any metallic objects from itself, due to the fact that the machine is a giant magnet and even tiny objects could become dangerous projectiles. - Thirdly, the patient must put in their head a helmet-like device called a head coil, and then lay themselves on the bed-shaped surface in front of the machine and wait for the doctor’s orders. - Fourth, once in this position the machine will start to track the areas of your brain with the highest concentration of blood. Additionally, the doctor in charge will usually ask patients to perform simple tasks like tap one of your fingers, in order for the images to detect which part of the brain is more active during those actions. During the process, the machine will be taking pictures for future analysis.

Return

Strengths and Limitations

Functional magnetic resonance imaging strengths: -Doesn't use radiation. -It provides qualitative data based on the blood flow levels in different areas of the brain. This means that this study is useful to measure who much an area affects and is being affected by phisical affections. -The FMRI use of the patient's actions is useful to define more precisely which areas of the brain are functioning at certain moments, which might make a diagnosis and analysis easier and more complete. Functional magnetic resonance imaging limitations: -FMRI produces very little quantitative data. -FMRI is very expensive, which makes it less accesible as a brain imaging technique. -Its only possible for it to capture a detailed image if the person is completly still and with very few movements. -It can only look at the blood flow in a whole area of the brain, its difficult for the image to be as precise as those of other methods.

Return

Example Study

Evidence for a vascular contribution to diffusion FMRI at high b value

A study conducted in 2007 by Karla. L. Milker and her team Aim: Test the efficiency of the use of FMRI in studies. Method: by measuring how much did the image become diffusing the more it stretched. As such, to prove their theories the team decided to conduct several FMRIs in patients who suffered from hypercapnia, a condition in which a person has an abnormal amount of carbon dioxide in its blood and can cause several symptoms both internal and external to the brain, in order to detect the fluctuations of the b value, a name the team gives to the amount of diffusion the resulting images presented. Results: The team found no evidence for an early increase in the b value in comparison with other tests made with traditional MRIs, thus proving that the difference in efficiency of both processes was close to being none. Conclusion: According to the study there is almost no diference in the efficiency of both processes.

Return

Sources

- Cleveland Clinic.(N/D). Functional MRI (fMRI). Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/25034-functional-mri-fmri-The open university.(2022). How FMRI works. The open university. https://www.open.edu/openlearn/body-mind/health/health- sciences/how-fmri-works -Buxton, B., R. et al.(2005). Dynamics of blood flow and oxygenation changes during brain activation: The balloon model. ISMRM, Vol 39, Issue 6. pp. 855-864. -Miller, L., K.(2007).Evidence for a vascular contribution to diffusion FMRI at high b value. Proceedings National Academy of Sciences, Vol 104, Issue 52. pp. 104-106.-Watson, S.(2022).How fMRI Works.Howstuffworks. https://science.howstuffworks.com/fmri4.htm -Mier, W.(2015).Advantages in functional imaging of the brain. Heidelberg University Hospital. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4436574/

Return