Comparison of Low-Dose Dobutamine–Gradient-Echo Magnetic Resonance Imaging and Positron Emission Tomography With [ ¹⁸ F]Fluorodeoxyglucose in Patients With Chronic Coronary Artery Disease

Abstract

Viable myocardium is characterized by preserved end-diastolic wall thickness and a dobutamine-inducible contraction reserve. Both parameters should be taken into account to maximize the sensitivity of MRI in the detection of regions with signs of viability on FDG-PET images.

Characterization of Dysfunctional Myocardium by Positron Emission Tomography and Magnetic Resonance

“…Revascularization was performed 31Ϯ21 and 30Ϯ27 days after the MR and PET studies, respectively, and follow-up MR was performed 11Ϯ2 months after intervention (without clinical evidence of myocardial infarction during follow-up). One patient with medical treatment died during the follow-up period, and 1 (Figure 1) demonstrates that the threshold value of 50% FDG uptake often used to predict functional recovery 22,23,25 corresponds to a rim thickness of Ϸ4.5 mm. Application of these PET and MR criteria for predicting functional recovery (Ն50% FDG uptake relative to the reference segment and rim thickness Ͼ4.5 mm on ce-MR, respectively) yielded 4 classes of myocardial segments, as follows: (1) thick metabolically viable segments (PET/MRϩ/ ϩ); (2) thin metabolically nonviable segments (PET/MRϪ/ Ϫ); (3) thin but metabolically viable segments (PET/MRϩ/ Ϫ); and (4) thick metabolically nonviable segments (PET/ MRϪ/ϩ).…”

“…Mismatch segments explain partly the scatter observed in this relationship, which indicates that viable tissue as defined by ce-MR may differ with respect to flow-metabolism balance. The PET threshold of Ն50% FDG uptake (predicting functional recovery 22,23,25 ) corresponds to a viable rim thickness on MR of Ϸ4.5 mm. These findings allow the subdivision of dysfunctional myocardial segments into various classes meeting both MR and PET criteria for recovery of function, only 1 criterion (intermediate segments), or none of these criteria.…”

“…11,12,14 A 50% FDG uptake (a cut off value often used to predict functional recovery 22,23,25 ) corresponded to a viable rim thickness on MR of Ϸ4.5 mm. Although segments above and below these thresholds are expected to recover function with high and low probability, the fate of intermediate segments (fulfilling only 1 criterion for functional recovery) is of particular interest.…”

“…This finding of metabolically viable myocardium that does not recover function after revascularization might be explained by a loss of contractile material in these segments to an extent that precludes contractile recovery. A reduction in wall thickness Ͻ5.5 mm 23 or a fibrous content exceeding 35% 11 predicted lack of functional recovery and translates into a rim of viable tissue of Ϸ4 mm (Ͼ65% of 5.5-mm wall thickness) necessary for contractile function. A severe alteration of metabolism was a common finding in PET-viable segments with a thin rim of viable tissue (Յ4.5 mm), as indicated by the high portion of mismatch segments of 59% in this class.…”

The role of imaging and molecular imaging in the early detection of metabolic and cardiovascular dysfunctions

“…End-diastolic wall thickness 45.5 mm and evidence of wall thickening after dobutamine injection 41-2 mm have been considered viable criteria. 54 Therefore, stress imaging is able to detect coronary artery deficit in asymptomatic patients.…”