Myocardial T1 mapping and determination of partition coefficients at 3 tesla: comparison between gadobenate dimeglumine and gadofosveset trisodium.

OBJECTIVE: To compare an albumin-bound gadolinium chelate (gadofosveset trisodium) and an extracellular contrast agent (gadobenate dimeglumine), in terms of their effects on myocardial longitudinal (T1) relaxation time and partition coefficient. MATERIALS AND METHODS: Study subjects underwent two imaging sessions for T1 mapping at 3 tesla with a modified look-locker inversion recovery (MOLLI) pulse sequence to obtain one pre-contrast T1 map and two post-contrast T1 maps (mean 15 and 21 min, respectively). The partition coefficient was calculated as ΔR1myocardium /ΔR1blood , where R1 is 1/T1. RESULTS: A total of 252 myocardial and blood pool T1 values were obtained in 21 healthy subjects. After gadolinium administration, the myocardial T1 was longer for gadofosveset than for gadobenate, the mean difference between the two contrast agents being -7.6 ± 60 ms (p = 0.41). The inverse was true for the blood pool T1, which was longer for gadobenate than for gadofosveset, the mean difference being 56.5 ± 67 ms (p < 0.001). The partition coefficient (λ) was higher for gadobenate than gadofosveset (0.41 vs. 0.33), indicating slower blood pool washout for gadofosveset than for gadobenate. CONCLUSION: Myocardial T1 times did not differ significantly between gadobenate and gadofosveset. At typical clinical doses of the contrast agents, partition coefficients were significantly lower for the intravascular contrast agent than for the extravascular agent.

Myocardial T1 mapping and determination of partition coefficients at 3 tesla: comparison between gadobenate dimeglumine and gadofosveset trisodium / Mapa T1 e coeficiente de partição do miocárdio em aparelho 3 tesla: comparação entre gadobenato de dimeglumina e gadofosveset trissódico

Abstract Objective: To compare an albumin-bound gadolinium chelate (gadofosveset trisodium) and an extracellular contrast agent (gadobenate dimeglumine), in terms of their effects on myocardial longitudinal (T1) relaxation time and partition coefficient. Materials and Methods: Study subjects underwent two imaging sessions for T1 mapping at 3 tesla with a modified look-locker inversion recovery (MOLLI) pulse sequence to obtain one pre-contrast T1 map and two post-contrast T1 maps (mean 15 and 21 min, respectively). The partition coefficient was calculated as ΔR1myocardium /ΔR1blood , where R1 is 1/T1. Results: A total of 252 myocardial and blood pool T1 values were obtained in 21 healthy subjects. After gadolinium administration, the myocardial T1 was longer for gadofosveset than for gadobenate, the mean difference between the two contrast agents being −7.6 ± 60 ms (p = 0.41). The inverse was true for the blood pool T1, which was longer for gadobenate than for gadofosveset, the mean difference being 56.5 ± 67 ms (p < 0.001). The partition coefficient (λ) was higher for gadobenate than gadofosveset (0.41 vs. 0.33), indicating slower blood pool washout for gadofosveset than for gadobenate. Conclusion: Myocardial T1 times did not differ significantly between gadobenate and gadofosveset. At typical clinical doses of the contrast agents, partition coefficients were significantly lower for the intravascular contrast agent than for the extravascular agent.

Resumo Objetivo: Avaliar o efeito da utilização de um agente de contraste intravascular baseado em gadolínio quelado a albumina (gadofosveset) no tempo T1 e no coeficiente de partição do miocárdio, quando comparado com um agente de contraste extravascular baseado no gadolínio não quelado a albumina (gadobenato). Materiais e Métodos: Os participantes do estudo foram submetidos a dois exames para aquisições do mapeamento T1 em aparelho de 3 tesla. Utilizando uma sequência de pulso modificada - modified look-locker inversion recovery (MOLLI) -, realizou-se uma etapa pré-contraste e duas etapas pós-contraste do mapa T1 (média de 15 e 21 minutos). O coeficiente de partição foi calculado como: ΔR1miocárdio /ΔR1sangue. Resultados: Um total de 252 valores de mapa T1 no miocárdio e no sangue foi obtido em 21 indivíduos saudáveis. Após a administração do meio de contraste, a diferença média do tempo T1 do miocárdio entre os agentes de contraste foi -7,6 ± 60 ms (p = 0,41) (isto é, gadobenato T1 < gadofosveset T1). Já no sangue, a diferença média de tempo T1 foi 56,5 ± 67 ms (p < 0,001) (isto é, gadobenato T1 > gadofosveset T1). O coeficiente de partição foi maior para o gadobenato (λ = 0,41) do que para o gadofosveset (λ = 0,33), refletindo uma eliminação mais lenta do gadofosveset em comparação com o gadobenato. Conclusão: Os tempos T1 do miocárdio não foram significativamente diferentes entre gadobenato e gadofosveset. Os coeficientes de partição foram significativamente mais baixos para o agente de contraste intravascular em comparação com o agente extravascular em doses clínicas típicas de cada contraste.

Peri-infarct zone characterized by cardiac magnetic resonance imaging is directly associated with the inflammatory activity during acute phase myocardial infarction.

Enhanced systemic inflammatory activity (SIA) during myocardial infarction (MI) and the extent of the peri-infarct zone characterized by cardiac magnetic resonance imaging (CMRi) are both associated with increased risk of life-threatening arrhythmias and sudden cardiac death. The present study investigated the existence of association between these two phenomena in 98 patients (55 ± 10 years) with ST segment elevation MI. Plasma levels of C-reactive protein (CRP), interleukin-2 (IL-2), and tumor necrosis factor (TNF) were measured on admission (D1) and on the fifth day post-MI (D5). CMRi was performed 2 weeks after MI to quantify peri-infarct zone (PIZ). Between D1 and D5, the increase in CRP (6.0 vs. 5.6 times; p = 0.02), IL-2 (3.6 vs. 3.4 times; p = 0.04) and tumor necrosis factor type α (TNF-α; 4.6 vs. 3.9 times; p = 0.001) were higher in patients with PIZ above the median than in the counterparts. PIZ was correlated with CRP-D5 (r = 0.69), delta-CRP (r = 0.7), IL-2-D5 (r = 0.5), delta-IL-2 (r = 0.6), TNF-α (r = 0.5), delta-TNF-α (r = 0.4; p = 0.0001). Enhanced activation of SIA during the acute phase of MI is directly related with generation of PIZ.

Myocardial T1 mapping with MRI: comparison of look-locker and MOLLI sequences.

PURPOSE: To evaluate the relationship between "Look-Locker" (LL) and modified Look-Locker Inversion recovery (MOLLI) approaches for T1 mapping of the myocardium. MATERIALS AND METHODS: A total of 168 myocardial T1 maps using MOLLI and 165 maps using LL were obtained in human subjects at 1.5 Tesla. The T1 values of the myocardium were calculated before and at five time points after gadolinium administration. All time and heart rate normalizations were done. The T1 values obtained were compared to determine the absolute and bias agreement. RESULTS: The precontrast global T1 values were similar when measured by the LL and by MOLLI technique (mean, 1004.9 ms ± 120.3 versus 1034.1 ms ± 53.1, respectively, P = 0.26). Postcontrast myocardial T1 time from LL was significantly longer than MOLLI from 5 to 25 min (mean difference, LL - MOLLI was +61.8 ± 46.4 ms, P < 0.001). No significant differences in T1 values were noted between long and short axis measurements for either MOLLI or LL. CONCLUSION: Postcontrast LL and MOLLI showed very good agreement, although LL values are higher than MOLLI. Precontrast T1 values showed good agreement, however LL has greater limits of agreement. Short and long axis planes can reliably assess T1 values.