Electronic Posters: Cardiovascular

Tuesday 13:30-15:30 Computer 28

13:30 3556. Radial Tagging for Assessment of Circumferential Myocardial Function

Melanie S. Kotys¹, Xiaopeng Zhou², Scott D. Flamm², Randy M. Setser<sup>2

1</sup>MR Clinical Science, Philips Healthcare, Cleveland, OH, United States; ²Imaging Institute, Cleveland Clinic, Cleveland, OH, United States

Myocardial tags applied in radial orientation using selective saturation bands may have distinct advantages over SPAMM methods for routine clinical examinations. We compared radial tagged images with 4-16 tag lines and grid tagged images in five volunteers. Analysis revealed that radial tags persisted longer than grid tags and had a comparable first acquired cardiac phase. There was no significant difference in end systolic strain or rotation and 12 radial tag lines had the least variation in both measures. Application of radial tags appears to be as efficient as SPAMM tagging with the potential for clinical analysis of circumferential myocardial function.

14:00 3557. Investigation of High Fat Diet Effects on Myocardial Trygliceride and Function in Mice

Marzena Wylezinska¹, Jordi L. Tremoleda¹, Jelena Anastasovska², Willy Gsell¹, Jimmy Bell<sup>2

1</sup>Biological Imaging Centre, Imaging Sciences Department, MRC Clinical Sciences Centre, Imperial College, London, United Kingdom; ²Metabolic Imaging Group, MRC Clinical Sciences Centre, Imperial College, London, United Kingdom

The aim was to investigate the effect of high fat diet on myocardial triglyceride and function in preclinical model. Male C57/Bl6 mice were maintained on a high (21%) fat (HF n=6) or a normal (3%) fat diet (C, n=5). Using MRI left ventricular ejection fraction (LVEF) was measured, while localized 1H MRS was used to estimate lipids content in the interventricular septum in animals. Lipid content was significantly increased in HF group, while trend was observed in LVEF decrease in HF group. These preliminary results suggest that high fat diet may have implications on myocardial lipid content and cardiac function.

14:30 3558. In Vivo Cardiac MRI Detects Differential Response to Partial and Complete Akt1 Deficiency

Katrien Vandoorne¹, Inbal E. Biton², Alon Harmelin², Michal Neeman<sup>1

1</sup>Biological Regulation, Weizmann Institute, Rehovot, Israel; ²Veterinary Resources, Weizmann Institute, Rehovot, Israel

The PKB/Akt family of intracellular protein kinases regulates cellular growth, proliferation, survival and metabolism. It is known that Akt1/PKBalpha controls heart size and function. Baseline left ventricular structure and function of Akt1/PKBalpha; null, heterozygote and wild type mice, were assessed using retrospectively reconstructed FLASH cine scans with the aid of navigator scans. Here, we showed in vivo, that LV mass and cardiac output are reduced in knockout animals. This reduction is consistent with the reduced body weight. Surprisingly, cardiac hypertrophy observed here by MRI of heterozygote mice, and noted also previously by ultrasound, was resolved in the full Akt1 knockout.

15:00 3559. Measurement of Changes in Left Ventricular Volume and Strain During Isovolumic Relaxation

June Cheng-Baron¹, Kelvin Chow¹, Ben T. Esch², Jessica M. Scott², Mark J. Haykowsky², John V. Tyberg³, Richard B. Thompson<sup>1

1</sup>Biomedical Engineering, University of Alberta, Edmonton, AB, Canada; ²Physical Therapy, University of Alberta, Edmonton, AB, Canada; ³Cardiac Sciences, University of Calgary, Calgary, AB, Canada

Left ventricular (LV) volume estimated using ventricular dimensions or surface markers have shown increasing volume during isovolumic relaxation, despite closed mitral and aortic valves. The goal of this study is to explain and interpret this volume increase in the context of ventricular relaxation. We measure a 4.6 mL mean increase in LV volume, which is correlated with changes in principle myocardial strains and compensated for by the descent of the mitral leaflets towards the apex. The motion of the leaflets and conformational changes in the LV during isovolumic relaxation likely reflect LV pressure decline and the development of ventricular suction.