Biomedical subjects

T D Ruddy

Publications and source records attributed to T D Ruddy.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Stress perfusion/metabolism imaging: a pilot study for a potential new approach to the diagnosis of coronary disease in women.

BACKGROUND: The diagnosis of coronary artery disease (CAD) in women continues to be a challenge. F-18 deoxyglucose (FDG) positron emission tomography (PET) has been used for detection of myocardial ischemia at rest. Little has been reported about FDG stress imaging. The aim of this pilot study was to assess stress FDG PET imaging for defining CAD in a group of women referred for chest pain. METHODS: Stress FDG imaging was performed in 19 women (mean age 59 +/- 10 years). All had abnormal stress testing before entering the study. FDG and 2-methoxy-2-methylpropyl isonitrile were injected at peak stress (treadmill n = 8, dipyridamole n = 11) followed by PET and single photon emission computed tomography image acquisitions. Myocardial ischemia was defined by regions that demonstrated both a defect on perfusion imaging and increased FDG uptake relative to uptake in normal perfusion zones. Defect/normal zone FDG ratios were also determined. Coronary angiography was performed on all patients. RESULTS: Average, or mean, body mass index was high at 29.2 +/- 5 kg/m2. Nine of 19 patients had significant CAD. Eight of 9 with CAD had FDG-defined ischemia. Nine of the 10 without CAD had negative FDG images (sensitivity 89%, specificity 90%). The average defect/normal zone FDG ratio was greater in patients with CAD than in those without (2.4 +/- 1.9 vs 0.9 +/- 0.4, P < .05). CONCLUSIONS: Regional FDG uptake in areas of perfusion defects with stress increased in this group with CAD. These pilot data suggest that stress FDG PET may be diagnostically helpful in obese female patients. This novel approach may complement current methods of CAD detection in women and warrants further study.

Aged↗

PubMedDate not supplied

Differentiation of myocardial ischemia and necrosis by technetium 99m glucaric acid kinetics.

BACKGROUND: Current clinical approaches may not always be helpful in the early differentiation of necrotic tissue from ischemic viable myocardium in patients with acute myocardial infarction. Tc-99m-glucaric acid is a carbohydrate ligand that may permit differentiation of necrosis from ischemia. However, the myocardial kinetics of Tc-99m-glucaric acid have not been well defined early after myocardial injury. The aim of this study was to evaluate the effect of necrosis in comparison to postischemic injury alone on the kinetics of Tc-99m-glucaric acid with the use of an isolated perfused rat heart model. METHODS AND RESULTS: Three groups of hearts were studied: group I: control (n = 6); group II: postischemia (15 minutes of no flow with complete reperfusion, n = 6); and group III: necrosis (90 minutes of no flow to induce necrosis with complete reperfusion, n = 6). Tc-99m-glucaric acid (1.3 +/- 0.6 mCi/L of buffer) was perfused for 30 minutes to evaluate tracer accumulation. Then tracer-free buffer was perfused for 45 minutes to evaluate clearance. The peak accumulation relative to the control group mean was significantly increased (p < 0.01) in group III (necrosis) (254% +/- 75%) compared with control (100% +/- 10%) and compared with postischemia (108% +/- 26%). On kinetic data analysis, the monoexponential clearance rate constant: (kc) was significantly reduced with necrosis (control: kc = 20.2 +/- 14.0 x 10(-4) sec-1; postischemia: kc = 22.3 +/- 15.2 x 10(-4) sec-1; and necrosis: kc = 1.2 +/- 0.3 x 10(-4) sec-1; p < 0.05). A retention fraction was calculated from the activity after 45 minutes of clearance corrected for the peak activity for each group. The necrotic group had significant myocardial retention in comparison to control and postischemia (control: 12% +/- 8%; postischemia: 14% +/- 16%; necrosis: 64% +/- 10%; p < 0.01). CONCLUSIONS: The accumulation and retention of Tc-99m-glucaric acid is markedly increased in the presence of myocardial necrosis in comparison to control and postischemic myocardial injury. In this model, Tc-99m-glucaric acid is capable of defining the presence of necrotic myocardial injury in comparison to postischemic injury alone. This agent may have potential application for the early differentiation of ischemic from necrotic myocardium in acute myocardial infarction.

Animals↗

PubMedDate not supplied

Establishing an approach for patients with recent coronary occlusion: identification of viable myocardium.

BACKGROUND: Revascularization of occluded coronary arteries after myocardial infarction (MI) may restore flow to viable myocardium and improve ventricular function. The aim of this pilot study was to determine the potential utility of thallium-201 viability imaging for the prediction of recovery of regional ventricular function in patients undergoing revascularization of total or subtotal occlusion of infarct-related arteries (TIMI 0-2 flow) during the convalescent period after MI. METHODS: Twenty-three patients were identified < 6 weeks after MI and underwent Tl-201 viability imaging (rest imaging, n = 16; stress/reinjection imaging, n = 7) and radionuclide angiography. Patients were revascularized with percutaneous transluminal coronary artery in 10, stent in 10, and bypass in 3. Follow-up radionuclide angiography at 3 months was used to assess recovery of regional wall motion. RESULTS: Among 41 abnormal wall motion segments in the infarct territories, the sensitivity, specificity, and accuracy for Tl-201 imaging in the prediction of recovery of regional function were 89% (25/28), 54% (7/13), and 78% (32/41), respectively. When 8 segments supplied by vessels with restenosis to >70% were excluded, specificity improved to 70%. Wall motion scores improved in those with adequate revascularization (1.6+/-1.4 vs 2.7+/-1.6; P < .001) but not in those with restenosis or occlusion (1.8+/-1.0 vs 2.0+/-1.6; P = NS). CONCLUSIONS: In patients with an occluded artery after MI, Tl-201 viability imaging can detect recoverable myocardium with reasonable accuracy and may help select which patients will most benefit from revascularization.

Adult↗