6. Nuclear medicine diagnostics of heart-vascular system: myocardial perfusion scintigraphy (during stress and rest) – radiopharmaceuticals, protocols, reversible and fixed defects, clinical application. Myocardial scintigraphy synchronously with the ECG (gated SPECT). Application of SPECT-CT.
Covers myocardial perfusion scintigraphy at stress and rest, explaining how tracer uptake reflects blood flow and how reversible, fixed and mixed defects are read. It compares Tc-99m sestamibi, tetrofosmin and thallium-201, and lists exercise and pharmacological stress agents with protocols. It also covers gated SPECT for ejection fraction and wall motion, the role of SPECT/CT attenuation correction, and common artefacts such as breast and diaphragmatic attenuation, with a coronary territory table.
Inside: 12 sections · 10 labelled pictures · 1 table · 1 formula · 16 flashcards · 15 min
Topic 6 of 50 in the MU Sofia syllabus for Nuclear Medicine (Medicine, Year 4). The free AceMed note covers it in 12 sections, about 2,111 words (15 min of reading), with 16 flashcards.
In this note
Topic 6: Nuclear Medicine Diagnostics of the Heart-Vascular System
Principle
Why is Stress Imaging Necessary?
Coronary Territory Table
Radiopharmaceuticals
Mechanism of Tracer Uptake
Stress Myocardial Perfusion Imaging
Pharmacological Stress Agents
Normal Myocardial Perfusion Scan
Perfusion Defect
Clinical Applications
Nuclear medicine diagnostics of digestive tract: oesophagus, intestines, liver
Topic 6: Nuclear Medicine Diagnostics of the Heart-Vascular System
Myocardial Perfusion Scintigraphy (Stress & Rest), Radiopharmaceuticals, Protocols, Reversible and Fixed Defects, Clinical Applications, Gated SPECT and SPECT/CT
Myocardial Perfusion Scintigraphy (MPS), also called Myocardial Perfusion Imaging (MPI), is a nuclear medicine investigation that evaluates:
Myocardial blood flow (perfusion)
Myocardial viability
Myocardial ischemia
Myocardial infarction (scar)
Left ventricular function (when gated SPECT is used)
It is one of the most widely used non-invasive investigations for diagnosing coronary artery disease (CAD).
Principle
The myocardium requires a continuous supply of oxygen-rich blood through the coronary arteries.
When a radioactive tracer is injected:
Normal myocardium receives adequate blood supply.
Therefore, more tracer reaches the myocardium.
The myocardium appears bright on the scan.
If coronary artery stenosis reduces blood flow:
Less tracer reaches that area.
It appears as a perfusion defect (cold area).
Thus: Tracer uptake is directly proportional to myocardial blood flow.
Why is Stress Imaging Necessary?
At rest, many patients with coronary artery disease have adequate blood flow because myocardial oxygen demand is low.
During exercise:
Heart rate increases.
Blood pressure increases.
Oxygen demand increases.
A diseased coronary artery cannot increase blood flow sufficiently.
