Abstract 2417: Late Acquisition for the Evaluation of Myocardial Viability by MSCT
Purpose: to determine the usefulness of MSCT for the detection of myocardial perfusion defects and for the evaluation of myocardial viability.
Methods: Sixty patients were evaluated with MSCT and Nuclear Medicine (NM) at rest, stress and in a late acquisitions. NM studies were performed with the injection of 30 mCi Tc-99 m Sestamibi and a 17-segmental analysis were evaluated in the short axis plane (6 basal, 6 mid-ventricular and 4 apical) and 1 segment in the long axis plane. The same three scans (rest, stress and late scan 10 minutes after stress) were performed by CT. For the stress scan 0.56mg/Kg of dypiridamol was administrated. Rest-stress CT and NM divided perfusion findings in
ischemia: perfusion defect presents in stress that disappears in rest,
necrosis: perfusion defect that appears in stress and persist in rest.
Late CT scan evaluate the behavior of the pathologic hypoperfusion segments. Performing a qualitative and quantitative analysis, ROIs were placed in each of the 17 segments to determine the HU of the normal or pathologic myocardium. A descriptive analysis was performed determining the mean density of the normal and pathologic myocardium at rest, stress and during the late scan.
Results: For the detection of hypoperfusion defects MSCT showed a sensitivity (S) of 89.6 % and a specificity (Sp) of 98.5 %. Normal myocardium showed at rest 102.03 HU, +/−22.7 whereas at stress it showed 105.6 HU, +/− 25.5. In the late scan the normal density was reduced to 56.6 HU, +/−14.8. The hypoperfusion defects at rest and stress showed a density of 46.9 +/− 10.7 and 46.6 +/− 18.0 HU respectively. In the late scan the hypoperfused segments presented 2 behaviors: the ones that persisted hypodense with density of 46+/−18 HU (non viable tissue) and the ones that showed hyperdensity with a density of 116.0+/−15 HU (viable tissue).
Conclusion: MSCT showed high S and SP for the detection of hypoperfusion defects. Late scan was useful to evaluate the viability of the pathologic segments. MSCT myocardial perfusion evaluation provides a better spatial resolution that improved the identification of sub-endocardial perfusion defects.