Quantification of Intramyocardial Lipid by Proton Magnetic Resonance Spectroscopy
| Status: | Completed |
|---|---|
| Conditions: | Cardiology |
| Therapuetic Areas: | Cardiology / Vascular Diseases |
| Healthy: | No |
| Age Range: | 18 - 45 |
| Updated: | 9/15/2018 |
| Start Date: | August 2005 |
| End Date: | June 2009 |
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.
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.
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.
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.
Inclusion Criteria:
- healthy volunteers
- heart transplant patients
- undergoing post transplant endomyocardial biopsy
- not experiencing significant rejection
- heart transplant patients must be 18-30 years old.
Exclusion Criteria:
- <18 or >45
- pregnant
- significant systemic illness
- actively ill
- acute transplant rejection
- any condition that would prevent a participant from completing the NMR spectroscopy
(i.e pacemakers, claustrophobia)
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