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Anisotropy is an artefact encountered in ultrasound, notably in muscles and tendons during a musculoskeletal ultrasound. In musculoskeletal applications, the artefact may prompt an incorrect diagnosis of tendinosis or tendon tear. When the ultrasound beam is incident on a fibrillar structure as...

Bone mineral density

Bone mineral density (BMD) is defined as amount of mineral (calcium hydroxyapatite) per unit of bone. Radiographic features BMD can be measured by various methods: gamma rays: replaced by radiographic methods single-energy photon absorptiometry (SPA) was superseded by the introduction of sin...

Bone scan

Bone scans are a nuclear medicine (scintigraphic) study that makes use of Technetium 99m (commonly Tc99m-methylene diphosphonate (MDP)) as the active agent. The study has three phases which follow intravenous injection of the tracer. Sometimes a fourth (delayed/delayed) phase is performed.  Cl...

Contrast media extravasation

Contrast media extravasation (CMEV) refers to the leakage of contrast media from the normal intravascular compartment into surrounding soft tissues; It is a well-known complication of contrast-enhanced CT scanning. It can also occur in MRI studies, but the complications are rare given the low vo...

Magic angle effect (MRI artifact)

The magic angle is an MRI artifact which occurs on sequences with a short TE (less than 32ms; T1W sequences, PD sequences and gradient echo sequences).  It is confined to regions of tightly bound collagen at 54.74° from the main magnetic field (B0), and appears hyperintense, thus potentially be...

Magnetic resonance neurography

Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral spinal nerves. It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions. Dedicated high-res...

Metal artifact reduction sequence

A metal artifact reduction sequence (MARS) is intended to reduce the size and intensity of susceptibility artifacts resulting from magnetic field distortion. A variety of techniques are used for reducing metal artifacts at MRI, both for addressing artifacts due to the presence of metal in the i...

Quantitative computed tomography

Quantitative computed tomography (QCT) is a bone mineral density (BMD) measurement technique in which the CT scanner is calibrated using solid phantoms (made of calcium hydroxyapatite, representing various bone mineral densities) placed under the patient in a pad. With this calibration, the Houn...

T1 rho

T1 rho, also referred to as T1ρ or "spin lock", is an MRI sequence that is being developed for use in musculoskeletal imaging. At the moment it is mostly investigational and does not yet have widespread clinical use. The "rho" in the sequence name refers to a "ro"tating frame and the sequence h...

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