MRS establishes link between myocardial triglyceride content and susceptibility to diabetes
September 14, 2007
The heart may hold secrets to predicting the future onset of Type 2 diabetes, with the help of proton MR spectroscopy. This elegant finding emerged from research by Lidia Szczepaniak, Ph.D., and colleagues at the University of Texas Southwestern in Dallas. Using anatomical MRI and metabolic MRS, they found that myocardial triglyceride content was 2.3 times higher in subjects with impaired glucose tolerance and 2.1 times higher in subjects with Type 2 diabetes than in normal subjects.
The heart may hold secrets to predicting the future onset of Type 2 diabetes, with the help of proton MR spectroscopy. This elegant finding emerged from research by Lidia Szczepaniak, Ph.D., and colleagues at the University of Texas Southwestern in Dallas. Using anatomical MRI and metabolic MRS, they found that myocardial triglyceride content was 2.3 times higher in subjects with impaired glucose tolerance and 2.1 times higher in subjects with Type 2 diabetes than in normal subjects. Cardiac steatosis in diabetes mellitus: a ¹H magnetic resonance spectroscopy study Circulation 2007;116:1170-1175 A multicenter research team led by Lidia Szczepaniak, Ph.D., from the University of Texas Southwestern, used proton spectroscopy to establish that impaired glucose tolerance, which preceded the onset of Type 2 diabetes, is accompanied by cardiac steatosis. Szczepaniak assigned 134 volunteers into four groups according to their body mass and glucose tolerance levels. MRI and MRS studies found that myocardial triglyceride content was 2.3 times higher in subjects with impaired glucose tolerance and 2.1 times higher in subjects with Type 2 diabetes than in lean volunteers. Left ventricular ejection fraction was normal for all groups.Added value of coronary artery calcium score as an adjunct to gated SPECT for the evaluation of coronary artery disease in an intermediate risk population JNM 2007;48(9):1424-1430 Radiology and cardiology researchers at University Hospital Zurich in Switzerland determined from this prospective trial of 77 patients that coronary artery calcium (CAC) scores may offer incremental diagnostic information over SPECT data for identifying patients with significant coronary artery disease and negative myocardial perfusion results. CAD scores, recorded by Dr. Philipp A. Kaufmann and colleagues, were significantly higher in subjects with perfusion abnormalities than in those who had normal SPECT results. A large percentage of patients with CAD had high CAC scores. Receiver operating characteristic analysis indicated that a CAC score of more than or equal to 709 was the optimal cutoff for detecting coronary disease missed by SPECT. The sensitivity of SPECT for the detection of significant coronary artery disease rose from 76% to 86% with the addition of a CAC test. Its specificity fell 5 percentage points to 86%, a decline that was not statistically significant. Is functional improvement after myocardial infarction predicted with myocardial enhancement patterns at multidetector CT? Radiology 2007;244:736-744 Israeli cardiologists learned by examining 26 middle-aged patients (average age 53 years), who had recently had a myocardial infarction, that the presence and size of perfusion defects and late enhancement with multislice CT is closely related to follow-up segment myocardial dysfunction and myocardial functional recovery. Dr. Jonathan Lessick and colleagues at the RamBam Healthcare Campus found from this prospective trial that all early myocardial perfusion deficits and late-enhancing regions corresponded with the region of the infarction determined with angiography and echocardiography. For patent arteries, late enhancement had a specificity and sensitivity of 73% and 85%, respectively, for predicting follow-up segment dysfunction, compared with 57% and 90% for early perfusion defects.Adenosine versus regadenoson comparative evaluation in myocardial perfusion imaging: Results of the ADVANCE phase III multicenter international trial J Nuc Card 2007;14(5):645-658 Regadenoson continued to show promise as a pharmacologic stress agent for myocardial perfusion studies in the second of three phase III clinical trials. The multicenter double-blinded trial, coordinated by Dr. Arni E. Iskandrian at the University of Alabama, Birmingham, involved 784 patients at 54 sites. Side-by-side interpretation of regadenoson and adenosine stress SPECT images generated comparable results for detecting reversible defects. The peak increase in heart rate was greater with regadenoson than adenosine, but the blood pressure nadir was similar. A prior identical trial led to the same positive conclusion. The agent is designed for rapid bolus delivery to selectively stimulate the A2A-adenosine receptor, thereby triggering coronary vasodilation. CV Therapeutics submitted a new drug application for regadenoson to the FDA in May. F-18 fluorodeoxyglucose positron emission tomography imaging of atherosclerotic plaque inflammation is highly reproducible J Am Coll Cardiol 2007;50:892-896 In New York City, Mount Sinai School Medicine researchers under the direction of Dr. Zahi Fayad, director of cardiovascular imaging, established the near-term reproducibility of FDG-PET of atherosclerosis. The finding is relevant because earlier research had established that FDG-PET can measure inflammation in the aorta, carotid, and vertebral arteries. By tracking inflammation over time, Fayad and others demonstrated that PET can potentially serve as a surrogate marker to track the effectiveness of drugs intended to treat atherosclerosis. Lead author Dr. James Rudd and colleagues found by imaging the carotid arteries and aorta of 11 subjects with FDG-PET that interscan plaque FDG variability during two weeks was extremely low, with favorable inter- and intraobserver agreement. The findings strengthen the case for FDG-PET as a noninvasive plaque imaging technique, according to the authors.The value of myocardial perfusion single-photon emission computed tomography in screening asymptomatic patients with atrial fibrillation for coronary artery disease J Am Coll Cardiol 2007;50:1080-1085 Dr. J. Wells Askew and colleagues at Mayo Clinic in Rochester, MN, established in a retrospective study of 374 asymptomatic patients with atrial fibrillation and 374 normal controls that factors other than obstructive coronary artery disease are responsible for increased mortality in this class of patients. Based on stress SPECT, stress sum scores were not significantly different between patients with known atrial fibrillation and normal controls, though stress sum scores predicted the likelihood of outcome for both groups. Because total mortality after 10 years was still significantly high among the atrial fibrillation patients compared to controls, Askew concluded that factors other than obstructive coronary artery disease must explain the difference.