Diagnosis Technique Mechanism AD Characteristics Identified
Computerized Tomography (CT) Scan CT scans utilize an integrative approach with motorized X-ray sources and advanced mathematical methods to construct two-dimensional (2-D) cross-sectional images of the patient. Using a computer, the 2-D images can then be coupled to create advanced three-dimensional images of biological systems. CT scans can identify regions of brain shrinkage and amyloid plaques. Additionally, CT scans are utilized to confirm that other brain abnormalities such as, tumors, subdural hematomas, and strokes are not the source of AD symptoms
Magnetic Resonance Imaging (MRI) MRIs implement a highly potent magnetic field to stimulate protons in the body to orient towards the applied magnetic field. Once the radiofrequency field initially applied is removed, MRI detectors measure the energy released by the protons to reorient with the magnetic field. Biological tissue varies across systems, with each having their own unique magnetic properties. MRIs can show regions afflicted with brain atrophy and detailed images of blood vessels in the brain. Furthermore, MRIs are employed to confirm that bleeding in the brain and fluid build-up are not contributing to the appearance of AD symptoms.
Positron Emission Tomography (PET) Scan
PET Scans carry out their function by utilizing an injected radioactive isotope that emits positrons. The emitted positrons then collide with electrons present in biological tissue to form two photons. These photons are detected by scintillation crystals integrated within the PET scanner. The scintillation crystals absorb the photons and then convert the light energy derived from the photons into applicable electrical signals.
Amyloid PET scans measure the pathological accumulation of beta-amyloid proteins. Tau PET scans identify the abnormal accumulation of tau proteins. Fluorodeoxyglucose (FDG) PET scans quantify energy utilization in the brain. Widespread studies have indicated that dementia patients often show decreased glucose consumption in certain regions of the brain.
Lumbar Punctures Lumbar punctures are performed by inserting a hollow needle into the subarachnoid space of the spinal column to collect samples of CSF. Lumbar punctures can identify abnormal levels of beta-amyloid 42, tau, and phospho-tau in CSF. All of these proteins are critical AD biomarkers.