Medical Imaging Techniques Quiz

MRI utilizes radiofrequency pulses and a strong magnetic field to differentiate soft tissue structures based on how they respond to these pulses. This creates images with different signals, appearing as varying shades of brightness or darkness.

MRI uses magnetic fields and radio waves to distinguish between different tissues. This allows for detailed visualization of soft tissues, like those in the brain, where CT scans may have limitations due to their reliance on X-ray attenuation.

MRI is a powerful tool for visualizing brain structures and identifying pathology. It can differentiate between white matter (rich in fat) and gray matter, as well as distinguish CSF (cerebrospinal fluid) based on its bright signal due to its fluid nature.

MRI is not limited to imaging the brain. It can be used to examine various parts of the body, including the heart, breast, and abdomen. Different parameters and sequences can be adjusted to highlight specific tissues and conditions.

MRI can be used for visualizing flowing substances like blood, CSF, and bile. The movement of these fluids generates unique signals, allowing for detailed study of their flow within vessels, organs, and tissues.

MRI can be used in the diagnosis of appendicitis to rule out other potential causes, such as a bowel obstruction. It provides detailed images of the appendix and surrounding tissues.

MRI is often used alongside echocardiography (ultrasound of the heart) to provide a more comprehensive assessment of cardiac function and abnormalities. It offers detailed views of heart structures, tissues, and blood flow.

MRI is used in conjunction with mammography to provide clearer visualization of breast tissue abnormalities and diagnose breast cancer.

The process of measuring and reconstructing the released signal/energy from an anatomical area to create a cross-sectional image.

The ability of anatomical tissue to respond to an external magnetic field and radiofrequency (RF) waves, which is necessary for generating an MR signal.

Chemical substances within the body that produce measurable signals in MRI, allowing for imaging.

The most abundant substance in the human body, containing a single proton, making it highly useful in generating MR images.

Clinical MRI relies on the signal generated by hydrogen atoms (protons) within the body.

Pathologies (diseases) often contain high levels of fluid (hydrogen), leading to strong signals and clear visualization in MR images.

The central part of an atom, containing protons and neutrons.

A subatomic particle with a positive charge, found in the nucleus of an atom.

A large magnet used in MRI that produces a strong magnetic field within a tunnel-shaped gantry where the patient is positioned.

The magnetic field is measured in Tesla (T). One Tesla is equal to 10,000 Gauss.

In MRI, the magnetic moments of hydrogen nuclei align themselves in one of two directions: parallel or anti-parallel to the external magnetic field.

Nuclei with a lower energy level are aligned parallel to the external magnetic field, while nuclei with a higher energy level are opposed (anti-parallel) to the magnetic field.

The magnetic effects of parallel and anti-parallel protons cancel each other out. However, there is a larger number of low energy nuclei aligned parallel, creating a net magnetic moment that is used in MRI.

The magnetic field used in MRI is much larger and more powerful than a bar magnet, ranging from 0.035 to 3.0 Tesla.

This stationary magnet produces a strong magnetic field within the tunnel-shaped gantry, where the patient lies during the exam.

The magnetic force is positive due to the net magnetization, but some protons repel.

The alignment of hydrogen nuclei in an external magnetic field, where a majority orient parallel to the field, generating a net magnetization vector (NMV).

The wobble of the NMV around the axis of the external magnetic field (B0).

The rate at which the NMV precesses around B0, measured in megahertz (MHz).

The equation that describes the relationship between the external magnetic field strength and the precessional frequency of hydrogen nuclei.

The frequency at which radiofrequency (RF) pulses must be emitted to be absorbed by hydrogen nuclei, allowing for signal acquisition in MRI.

The process where RF pulses are emitted at 90 degrees to the NMV, causing the NMV to rotate away from the longitudinal axis (z-axis) into the transverse plane.

The decay of the transverse magnetization signal after an RF pulse, due to the realignment of hydrogen nuclei back to their original state.

The process of hydrogen nuclei returning to equilibrium with the magnetic field after RF pulse excitation. It involves the recovery of longitudinal magnetization and the disappearance of transverse magnetization.

The unique value that determines how easily a nucleus precesses in a magnetic field. It is a constant that doesn't change with the magnetic field strength.

The magnetic field strength applied during MRI scanning.

The state where hydrogen protons are synchronized in their precession, allowing for a strong signal for imaging.

The position of a magnetic moment in its precessional path. It describes how far along the precession cycle a nucleus is.

The state where multiple hydrogen protons are precessing randomly and are not synchronized.

The unique resonant frequency at which hydrogen protons will flip their spin when exposed to a radiofrequency pulse.

The process where hydrogen protons absorb energy and flip their spins when exposed to a radiofrequency pulse that matches their Larmor frequency.

The time it takes for transverse magnetization to decay to 37% of its original value.

The difference in T2 relaxation times between different tissues allows for differentiation in MRI images.

The process of protons losing phase coherence after an RF pulse is turned off, resulting in a loss of signal.

Fat has a faster T2 decay because its closely packed molecules limit proton motion.

Water has a slower T2 decay because its freely moving molecules maintain phase coherence for longer.

The process of longitudinal magnetization returning to its equilibrium value after an RF pulse.

Fat has a faster T1 recovery because its lower energy bonds allow for faster energy dissipation.