Sammendrag
Purpose: Manganese (Mn) releasing contrast media may have a future potential in cardiac MRI (MnMRI). Since Mn ions enter cardiac cells via calcium channels and accumulate intracellularly for hours, MnMRI may be applied for the study of cardiac inotropy and viability. We wanted to examine magnitude and duration of changes in longitudinal relaxivity (R1) in normal human myocardium after infusion of TeslascanÔ (Amersham Health) which contains Mn dipyridoxyl diphosphate and is approved for liver MRI. Material and Methods: 15 healthy volunteers were included in 3 groups. MR examinations were undertaken on a “Siemens Symphony" 1.5 T using an IR-turbo-FLASH sequence. After initial myocardial R1 estimations the respective groups received 5, 10 and 15 μmol/kg of Teslascan i.v. over 30 minutes. R1 measurements were then repeated at 0.5, 1, 2, 4, 8 and 24 hours. Results: The left ventricular R1-prevalue was 0.977 s-1 (+/- 0.042). R1 increased on average (all 15 subjects) 0.406 s-1 (+/- 0.093). The increase was present 0.5 hours after ended infusion, remained relatively constant during the first 2 hours, and then declined to 0.180 (+/- 0.099) after 24 hours. Dosage above 5 μmol/kg resulted only in slightly higher R1values. No side-effects or discomfort were observed during or immediately after the infusion. Conclusion: We conclude that a Mn releasing contrast medium as Teslascan may be promising for studies of cardiac function and probably also viability as an about 40 % increase in R1 was observed even with the low dose (5 mmol/kg) approved for liver MRI.
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