The role of quantitation in clinical nuclear cardiology: the University of Virginia approach.

Measurement of regional myocardial tracer concentration after stress and at rest allows the establishment of normal standards for myocardial perfusion and reversibility and provides a reference from which to determine disease severity and change in response to treatment. Using the partial-volume effect, we can also conveniently estimate regional myocardial thickening fractions corresponding to the same segments used for perfusion quantitation. This adds close comparison of perfusion and function as an aid to viability assessment and for recognition of possible ischemic dysfunction in cases of balanced ischemia or globally exhausted coronary flow reserve. Volume measurements are added to routinely determine body surface area-normalized end-systolic and end-diastolic volume indices. Left ventricular ejection fraction is estimated from both volume measurements and from regional thickening fractions. Reduced regional thickening fractions and elevated end-systolic volume index are early indicators of myopathy, and these measurements may add significant information to the traditional perfusion study, particularly in cases of hypertrophy and diastolic dysfunction.