Quantification of Intramyocardial Lipid by Proton Magnetic Resonance Spectroscopy
Condition: Heart Transplantation
Study type: Interventional

Summary: 
      Accumulation of triglycerides in heart tissue has been associated with changes in left
      ventricular function which can lead to heart failure. Proton magnetic resonance spectroscopy
      is currently the only non-invasive in vivo method to measure myocardial triglycerides
      content. The primary goal of this study was to determine if Magnetic Resonance Spectroscopy
      could effectively measure myocardial triglyceride content in myocardial heart tissue. Thus,
      quantitative and reliable techniques to monitor in vivo triglyceride accumulation in the
      heart are important for disease diagnosis and management. Currently, no such imaging method
      exists.
    

Detailed description: 
      Because routine biopsy of the myocardium is not feasible, MRS is the most promising technique
      for the quantification of myocardial triglycerides. MRS is routinely used to precisely
      characterize metabolite concentrations in muscle and liver. 14-16 Studies such as monitoring
      the levels of deoxymyoglobin and real-time tracking of the postprandial accumulation of
      cellular lipids are examples of its diversity and potential.15,17,18 Generally, these studies
      suggest that the reproducibility of MRS is between 2 and 6%.18,19 In vivo cardiac MRS
      provides unique challenges because of the requirement to compensate for concurrent heart and
      lung motion. Using cardiac and respiratory gating to minimize motional artifacts, an initial
      validation study found a variation of 17% for sequential measurements, attributing the major
      error to residual motional effects. 20 Moreover, measurements were limited to the
      inter-ventricular septum. Using navigator and cardiac gating appeared to give a slight, 4%,
      improvement, but this was a preliminary study and no validation was done.21 For a
      comprehensive clinical validation, other reproducibility factors must be addressed.
      Variations due to post-processing, coil placement and calibration, trigger reproducibility,
      internal versus external standard, shimming, and protocol sequence variables such as pulse
      quality, gradient strength, voxel size, relaxation time, echo time, and the number of scan
      repetitions are all known sources of reproducibility. 17,19,22-24 All of these variables must
      be characterized in order to achieve optimal inter- scanner and subject reproducibility along
      with accurate treatment tracking capability. Therefore, 10 normal healthy volunteers were
      imaged to determine the reliability of the MRS protocol with test-re-test measurements. The 8
      heart transplant patients were imaged prior to their routine heart biopsies, and then the
      myocardial biopsy tissue was measure and compared to the pre-biopsy images.
    

Intervention name(s): Magnetic Resonance Spectroscopy; Ex vivo heart biopsy
Intervention type(s): Procedure; Procedure
Intervention description(s): Magnetic Resonance Spectroscopy is a noninvasive procedure that provides detailed body images on any plane.; Heart transplant patients will have their normal clinical routine heart biopsy
Other intervention name(s): MRS; heart biopsy
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Compare magnetic resonance imaging measurements of triglyceride accumulation in myocardial tissue with ex vivo myocardial tissue collected from heart transplant patients who have had routine clinical heart biopsy.
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Heart; Transplant; MRS; MRI; Spectroscopy