History of the Wada Test

Author(s):  
David W. Loring ◽  
Kimford J. Meador

This chapter discusses the origins and development of the Wada test. Wada testing, named after Juhn A. Wada, M.D., is the technique of arterial administration of amobarbital (or other short acting barbiturate) to transiently inactivate brain function in the distribution of the injected artery during which cognitive testing is performed. The procedure was developed to establish cerebral language dominance in the late 1940s, and it became a routine component of the preoperative evaluation for epilepsy surgery in the mid-1950s. However, the use of Wada testing as the primary technique to identify cortical language regions and predict risk of post-operative memory decline has been increasingly displaced by electroencephalogram (EEG) video monitoring, magnetic resonance imaging (MRI) of hippocampus, positron emission tomography (PET), single photon emission computed tomography (SPECT), functional MRI (fMRI), and even multi-modality imaging.

Author(s):  
Carlos Bárcena ◽  
Chalermchai Khemtong ◽  
Girija S. Chaubey ◽  
Chase W. Kessinger ◽  
J. Ping Liu ◽  
...  

Molecular imaging has become a rapidly evolving field used in various applications to target macromolecules and biological process [1,2]. Various imaging systems, such as single photon emission computed tomography (SPECT), positron emission tomography (PET), computerized tomography (CT), and magnetic resonance imaging (MRI), use non-invasive techniques that provide disease-specific information through diagnostic imaging. Early detection of disease demonstrates the potential benefit of these systems.


2000 ◽  
Vol 6 (2) ◽  
pp. 109-119 ◽  
Author(s):  
John O'Brien ◽  
Bob Barber

Neuroimaging is traditionally divided into structural and functional imaging. Structural imaging looks at brain structure or anatomy and includes computed tomography (CT) and magnetic resonance imaging (MRI). Functional techniques seek to examine the physiological functioning of the brain, either at rest or during activation, and include single photon emission computed tomography (SPECT), positron emission tomography (PET), MRI spectroscopy, functional MRI (fMRI) and encephalographic brain mapping. Although fMRI, MRI spectroscopy and brain mapping are likely to have clinical applications in the near future, the main imaging modalities of current clinical relevance to psychiatrists are CT, MRI and SPECT, which will be the focus of this article.


Author(s):  
Mark Woolrich ◽  
Mark Jenkinson ◽  
Clare Mackay

The brain is a highly complex system that is inaccessible to biopsy, which puts human brain imaging at the heart of our attempts to understand psychiatric disorders. Imaging has the potential to uncover the pathophysiology, provide biomarkers for use in the development and monitoring of treatments, and stratify patients for studies and trials. This chapter introduces the three main brain imaging technologies that are used to assay brain structure and function: magnetic resonance imaging (MRI), molecular imaging positron emission tomography (PET), and single-photon emission computed tomography (SPECT); electrophysiology [electroencephoaography (EEG)]; and magnetoencephalograpy (MEG). The chapter outlines the principles behind their use and the nature of the information that can be extracted. Together, these brain imaging methods can provide complementary windows into the living brain as an increasingly essential suite of tools for experimental medicine in psychiatry.


2020 ◽  
Vol 21 (23) ◽  
pp. 9190
Author(s):  
Olga Krasnovskaya ◽  
Daniil Spector ◽  
Alexander Zlobin ◽  
Kirill Pavlov ◽  
Peter Gorelkin ◽  
...  

One of the hallmarks of Alzheimer’s disease (AD) is the deposition of amyloid plaques in the brain parenchyma, which occurs 7–15 years before the onset of cognitive symptoms of the pathology. Timely diagnostics of amyloid formations allows identifying AD at an early stage and initiating inhibitor therapy, delaying the progression of the disease. However, clinically used radiopharmaceuticals based on 11C and 18F are synchrotron-dependent and short-lived. The design of new metal-containing radiopharmaceuticals for AD visualization is of interest. The development of coordination compounds capable of effectively crossing the blood-brain barrier (BBB) requires careful selection of a ligand moiety, a metal chelating scaffold, and a metal cation, defining the method of supposed Aβ visualization. In this review, we have summarized metal-containing drugs for positron emission tomography (PET), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) imaging of Alzheimer’s disease. The obtained data allow assessing the structure-ability to cross the BBB ratio.


2020 ◽  
Vol 13 (12) ◽  
pp. 436
Author(s):  
Kyangwi P. Malikidogo ◽  
Harlei Martin ◽  
Célia S. Bonnet

Zinc and copper are essential cations involved in numerous biological processes, and variations in their concentrations can cause diseases such as neurodegenerative diseases, diabetes and cancers. Hence, detection and quantification of these cations are of utmost importance for the early diagnosis of disease. Magnetic resonance imaging (MRI) responsive contrast agents (mainly Lanthanide(+III) complexes), relying on a change in the state of the MRI active part upon interaction with the cation of interest, e.g., switch ON/OFF or vice versa, have been successfully utilized to detect Zn2+ and are now being developed to detect Cu2+. These paramagnetic probes mainly exploit the relaxation-based properties (T1-based contrast agents), but also the paramagnetic induced hyperfine shift properties (paraCEST and parashift probes) of the contrast agents. The challenges encountered going from Zn2+ to Cu2+ detection will be stressed and discussed herein, mainly involving the selectivity of the probes for the cation to detect and their responsivity at physiologically relevant concentrations. Depending on the response mechanism, the use of fast-field cycling MRI seems promising to increase the detection field while keeping a good response. In vivo applications of cation responsive MRI probes are only in their infancy and the recent developments will be described, along with the associated quantification problems. In the case of relaxation agents, the presence of another method of local quantification, e.g., synchrotron X-Ray fluorescence, single-photon emission computed tomography (SPECT) or positron emission tomography (PET) techniques, or 19F MRI is required, each of which has its own advantages and disadvantages.


2000 ◽  
Vol 10 (1) ◽  
pp. 55-68 ◽  
Author(s):  
H. Förstl ◽  
F. Hentschel

IntroductionThis is a review of recent and clinically relevant work on neuroimaging and its contribution to the diagnosis of neurodegenerative or other neurological and psychiatric diseases in older patients. Earlier research has been summarized in our previous review. We include publications on cranial computed tomography (CT) and magnetic resonance imaging (MRI), on single photon emission computed tomography (SPECT) and positron emission tomography (PET), electroencephalo-graphy (EEG), and on other methods.


2021 ◽  
Vol 22 (2) ◽  
pp. 755
Author(s):  
Vincent Q. Sier ◽  
Margreet R. de Vries ◽  
Joost R. van der Vorst ◽  
Alexander L. Vahrmeijer ◽  
Cornelis van Kooten ◽  
...  

Surgeons rely almost completely on their own vision and palpation to recognize affected tissues during surgery. Consequently, they are often unable to distinguish between different cells and tissue types. This makes accurate and complete resection cumbersome. Targeted image-guided surgery (IGS) provides a solution by enabling real-time tissue recognition. Most current targeting agents (tracers) consist of antibodies or peptides equipped with a radiolabel for Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT), magnetic resonance imaging (MRI) labels, or a near-infrared fluorescent (NIRF) dye. These tracers are preoperatively administered to patients, home in on targeted cells or tissues, and are visualized in the operating room via dedicated imaging systems. Instead of using these ‘passive’ tracers, there are other, more ‘active’ approaches of probe delivery conceivable by using living cells (macrophages/monocytes, neutrophils, T cells, mesenchymal stromal cells), cell(-derived) fragments (platelets, extracellular vesicles (exosomes)), and microorganisms (bacteria, viruses) or, alternatively, ‘humanized’ nanoparticles. Compared with current tracers, these active contrast agents might be more efficient for the specific targeting of tumors or other pathological tissues (e.g., atherosclerotic plaques). This review provides an overview of the arsenal of possibilities applicable for the concept of cell-based tracers for IGS.


Author(s):  
Allison C. Nugent ◽  
Maura L. Furey

Neuroscience research has clearly demonstrated neurological correlates of psychological disorders. We believe that neuroscience, particularly neuroimaging, has great potential to increase our understanding of these disorders, leading to more effective treatments, prevention, and perhaps even cure. Nevertheless, the popular media is replete with misinformation and exaggerated claims. The present chapter is intended to give the reader the necessary knowledge to critically evaluate neuroimaging studies of psychological disorders. We provide an overview of all the major neuroimaging techniques, example studies relevant to psychological disorders (with a particular emphasis on depression), particular pitfalls and caveats associated with each technique, and the promise of each technique. We first cover the nuclear imaging techniques, single photon emission computed tomography (SPECT) and positron emission tomography (PET). We then explore several magnetic resonance imaging (MRI) techniques, both structural and functional. Finally, we give an overview of the electrophysiological techniques, electroencephalography (EEG) and magnetoencephalography (MEG). Each of these techniques has particular strengths, and particular weaknesses. At this point, none of these tools are diagnostic, but each one provides a unique window into psychological disorders. When applied in a methodologically rigorous and statistically rigorous manner, neuroimaging has great promise for achieving greater understanding of psychological disorders, and relieving the great burdens they cause.


2012 ◽  
Vol 113 (2) ◽  
pp. 328-339 ◽  
Author(s):  
Susan R. Hopkins ◽  
Mark O. Wielpütz ◽  
Hans-Ulrich Kauczor

From the first measurements of the distribution of pulmonary blood flow using radioactive tracers by West and colleagues ( J Clin Invest 40: 1–12, 1961) allowing gravitational differences in pulmonary blood flow to be described, the imaging of pulmonary blood flow has made considerable progress. The researcher employing modern imaging techniques now has the choice of several techniques, including magnetic resonance imaging (MRI), computerized tomography (CT), positron emission tomography (PET), and single photon emission computed tomography (SPECT). These techniques differ in several important ways: the resolution of the measurement, the type of contrast or tag used to image flow, and the amount of ionizing radiation associated with each measurement. In addition, the techniques vary in what is actually measured, whether it is capillary perfusion such as with PET and SPECT, or larger vessel information in addition to capillary perfusion such as with MRI and CT. Combined, these issues affect quantification and interpretation of data as well as the type of experiments possible using different techniques. The goal of this review is to give an overview of the techniques most commonly in use for physiological experiments along with the issues unique to each technique.


2011 ◽  
Vol 9 (2) ◽  
pp. 107 ◽  
Author(s):  
Dmitriy Kireyev ◽  
Keenan Adib ◽  
Kian Keong Poh ◽  
Mofid Khalil ◽  
Michael F Wilson ◽  
...  

Ischemic cardiomyopathy is one of the most common causes of congestive heart failure. Despite multiple therapeutic options, morbidity and mortality remain high. Revascularization is one of the best options to improve ejection fraction and survival in patients with hibernating myocardium. This article discusses the role of positron emission tomography (PET), single-photon emission computed tomography (SPECT), dobutamine stress echocardiography (DSE), and magnetic resonance imaging (MRI)-based viability studies and their comparative evaluation.


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