A match describes an activity loss in perfusion and ventilation scintigraphy.

A mismatch describes an activity loss in lung perfusion scintigraphy combined with normal ventilation scintigraphy, e.g. in case of pulmonary embolism.

A multiphase bone scintigraphy (bone scan) is a nuclear medical examination including blood flow images, immediate images, and delayed images.
The blood flow study is a dynamic sequence of planar images of the bone region of interest obtained during the injection of the radiopharmaceutical (radioactive tracer).
The immediate phase (blood pool or soft tissue study) include one or more static images of selected regions, obtained immediately after the blood flow phase within 10 min.
Delayed images (usually whole body) are usually acquired 2-5 hours after injection. Later (6-24 hour) delayed images result in a higher target to background ratio and may permit better evaluation of the pelvis if this was obscured by bladder activity on the routine images. This late imaging may be particularly helpful in patients with renal insufficiency or peripheral circulatory disorders and those with urinary retention.

(NAA) Neutron activation analysis is a very sensitive analytical technique to determine even very low concentration of chemical elements, trace elements for example, in small biological samples.
NAA becomes commercial available in the USA in 1960.
In the activation process stable nuclides in the sample, which is placed in a neutron beam (neutron flux, 90-95% are thermal neutron with low energy levels under 0.5 eV), will change to radioactive nuclides through neutron capture (artificial radioactivity). These radioactive nuclides decay by emitting alpha-, beta-particles and gamma-rays with a unique half-life. Qualitative and quantitative analysis of the sample is done with a high-resolution gamma-ray spectrometer.
NAA is subdivided into the following techniques:

A peak is a maximum of activity.