Myocardial Perfusion Imaging (MPI) with Radioisotopes

Flashcards covering the fundamentals of Myocardial Perfusion Imaging, including anatomy, pharmacology, radiopharmaceuticals, and patient preparation based on clinical guidelines.

What is the primary purpose of Myocardial Perfusion Imaging (MPI)?

To show the distribution of blood flow (perfusion) in the myocardium of the left ventricle at cardiovascular rest and stress.

According to NICE, for which patients is MPI recommended as part of an investigational strategy?

People with established CAD who remain symptomatic following myocardial infarction or reperfusion interventions.

Which coronary artery is responsible for perfusing the anterior and septal regions?

The LAD (left coronary artery).

Which coronary artery perfuses the lateral region of the heart?

The LCx (left circumflex).

Which coronary artery perfuses the inferior and inferoseptal regions?

The RCA (right coronary artery).

What is the clinical definition of 'ischaemic myocardium' in the context of MPI?

Reduced perfusion that is adequate at rest but not at stress.

How is 'hibernating myocardium' described?

The muscle is alive, but perfusion is very poor and insufficient to contract.

Define 'Effective Dose' and its unit of measurement in nuclear medicine.

The energy imparted from ionising radiation in tissue, corrected for radiation and tissue type, measured in $mSv$.

What is the physical half-life of ${}^{99m}Tc$?

$$6\,hrs$$

What is the formula used to calculate the effective half-life ($T_{eff}$)?

$$\frac{1}{T_{eff}} = \frac{1}{T_{phys}} + \frac{1}{T_{biol}}$$

What are the two most common radiopharmaceuticals used for MPI?

Tetrofosmin (Myoview) and MIBI (Cardiolite), both labelled with ${}^{99m}Tc$.

What is the target heart rate required for a patient during an exercise stress test?

$85\%$ of target heart rate, calculated as $(220 - \text{age})$.

What is the typical half-life of Adenosine when used as a pharmacological stressing agent?

$$\lt 10\,sec$$

Why must patients avoid caffeine for 12 hours prior to an MPI stress test?

Caffeine interferes with the response to stressing agents such as Adenosine.

What specific heart rate-limiting drugs should be avoided before MPI?

Beta blockers, dipyridamole, calcium channel blockers, and theophyllins.

What is the purpose of a 'bulls-eye' polar plot in MPI?

It is a way to display 3D perfusion information in a 2D form for display.

How is the Left Ventricular Ejection Fraction (LVEF) calculated in gated MPI studies?

$$LVEF = \frac{EDV - ESV}{EDV} \times 100\%$$

Which anatomical feature typically causes attenuation artefacts in the anterior and lateral walls for female patients?

Breast attenuation.

According to IRMER Regulation 12, what principle must be followed regarding radiation doses?

Doses must be kept as low as reasonably practicable (ALARP).

What is the typical effective dose for a stress and rest study using ${}^{99m}Tc\text{-Sestamibi}$?

$$8.5\,mSv$$