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We report an initial investigation of a subtraction-based method to estimate right ventricle ejection fraction (RVEF) from ECG-gated planar equilibrium radionuclide angiography (ERNA) data. Twenty-six consecutive patients referred for scintigraphic evaluation of cardiac function prior to chemotherapy had ECG-gated first-pass (FP) imaging and ERNA imaging performed following the same radiotracer injection. RVEF was computed from FP images (RVEF FP ) and separately from ERNA images (RVEF ERNA ). Standard methods for computing ejection fractions were used to obtain RVEF FP values. RVEF ERNA values were obtained using harmonic subtraction of the left ventricular contribution from a biventricular region of interest contoured on the equilibrium images acquired in the shallow right anterior oblique projection. Clinically acquired chest CT data were used to derive information regarding the relative position of the left and right ventricle and about the presence of pulmonary artery enlargement. Computation of RVEF ERNA was successful for each of the 26 patients. Computation of RVEF FP failed for four patients. For the 22 patients for which RVEF was computed using both methods, the average RVEF FP was 49% and the average RVEF ERNA was 51%, with coefficients of variation of 11 and 7.5%, respectively. Low RVEF ERNA values were associated with pulmonary artery dilation. Estimation of RVEF ERNA , using a harmonic subtraction-based method of computation is clinically feasible and accurate in the patient population studied. The results support further investigation in patients with frank heart failure.

Unlabelled: After the extravasation of a therapeutic dose of (131)I-metaiodobenzylguanidine that produced a radiation burn to a patient's forearm, we instituted a catheter placement verification protocol., Methods: Before therapy infusion, proper placement is verified by administering 37 MBq of (99m)Tc-pertechnetate through the catheter, and monitoring activity at the administration site and on the contralateral extremity. A dosimetric model describing both high-rate and low-rate dose components was developed and predicted that the basal epidermal layer received a radiation dose consistent with the observed moist desquamation radiation skin toxicity., Results: No extravasation incidents have occurred since the verification procedure was instituted., Conclusion: To protect against radiation injury from extravasation of therapeutic radionuclides, test administration of a small (99m)Tc dose with probe monitoring of comparable sites in both upper extremities appears to be an effective preventive measure.

The metabolic syndrome represents a constellation of risk factors caused by insulin resistance, dyslipidemia, hypertension, and obesity, resulting in elevated coronary disease risk. From a multicenter prospective registry of 7,849 patients, the relation among the metabolic syndrome, diabetes, and risk stratification with stress technetium-99m tetrofosmin single photon-emission computed tomography (SPECT) was evaluated. The percentage of stress myocardial defects was calculated as < or = 5%, 5.1% to 10%, 10.1% to 15%, and > 15%. A Cox proportional-hazards model was used to estimate cardiovascular death or myocardial infarction (n = 752). Of 7,849 patients, 42% had the metabolic syndrome. Patients with the metabolic syndrome had an 84% 2-year event-free survival rate, lower than patients with normal metabolic status (p <0.0001). In patients with the metabolic syndrome, the percentage of moderate to severely abnormal SPECT findings ranged from 11% to 44% for those with 3 to 5 risk factors for the metabolic syndrome. There was an additive relation between the number of risk factors for the metabolic syndrome and the extent and severity of abnormalities in SPECT findings (p <0.0001). Patients with 5 risk factors for the metabolic syndrome were at the greatest risk, with hazard ratios from 7.8- to 14.1-fold for mild to severely abnormal SPECT findings. For diabetic patients requiring combined oral and insulin therapy, relative risk ratios increased from 15 to 21.4 for patients with > 5% to > 15% stress myocardial perfusion defects. In conclusion, cardiovascular prognosis is affected by the degree of metabolic dysfunction, and stress-induced reductions in myocardial perfusion provide an accurate means for near-term risk stratification.

Objectives: This study was designed to evaluate the differential prognostic value of gated single-photon emission computed tomographic imaging (SPECT) imaging in an ethnically diverse multicenter registry., Background: Ethnic minority patient populations have reportedly higher coronary heart disease mortality with greater comorbidity and a clustering of risk factors at a significantly younger age when compared with Caucasian, non-Hispanic patients. Despite our increasingly diverse population, the predictive accuracy of cardiac imaging in ethnic minority patients is ill-defined., Methods: A total of 7,849 patients were prospectively enrolled in a registry of patients undergoing exercise (44%) or pharmacologic stress (56%) technetium-99m tetrofosmin SPECT. Scans were scored using a 20-segment myocardial model with a 5-point severity index. Multivariable Cox proportional hazards models were employed to assess time to death or myocardial infarction., Results: A total of 1,993 African-American, 464 Hispanic, and 5,258 Caucasian non-Hispanic patients underwent SPECT imaging. African-American and Hispanic patients more often had a history of stroke, peripheral arterial disease, angina, heart failure, diabetes, hypertension, and smoking at a younger age. Moderate or severely abnormal SPECT scans were noted in 21%, 17%, and 13% of African-American, Hispanic, and Caucasian non-Hispanic patients, respectively (p < 0.0001). Cardiovascular death rates were highest for ethnic minority patients (p < 0.0001). Annual rates of ischemic heart disease death ranged from 0.2% to 3.0% for Caucasian non-Hispanic and 0.8% to 6.5% for African-American patients with low-risk to severely abnormal SPECT scans (p < 0.0001). For post-stress ejection fraction <45%, annualized risk-adjusted death rates were 2.7% for Caucasian non-Hispanic patients versus 8.0% and 14.0% for African-American and Hispanic patients (p < 0.0001)., Conclusions: The current results from a large observational registry reveal that exercise and pharmacologic stress SPECT effectively predicts major cardiovascular events in a large cohort of African-American and Hispanic patients evaluated for suspected myocardial ischemia. These results provide further evidence that ethnic minority patient populations have a worsening outcome related to cardiovascular disease.

The use of gallium for pulmonary diseases is hampered by its relative lack of specificity, typical 1- to 3-day delay between injection and imaging time, and suboptimal imaging characteristics. Other nuclear and nonnuclear imaging modalities, such as (18)F-fluorodeoxyglucose positron emission tomography (PET) and high-resolution chest computed tomography, have replaced gallium in many clinical algorithms. Yet gallium and other radiotracers, such as thallium, sestamibi, and labeled white blood cells, are useful in many specific clinical situations involving lymphoma and other neoplasias, inflammatory processes such as sarcoid and interstitial pneumonia, tuberculosis and other infections, and the acquired immune deficiency syndrome. Gallium and some of the other single-photon agents still have value in establishing a diagnosis, assessing the location and extent of disease, differentiating active disease from chronic scarring, guiding potential biopsy, and determining recurrence and response to therapy in patients with certain lung diseases, particularly when access to PET imaging is not available., (Copyright 2002, Elsevier Science (USA). All rights reserved.)