Tc-99m tetrofosmin myocardial distribution 4 hours post injection.

The recommended protocol for Tc99m tetrofosmin myocardial imaging suggests either a one- or two day imaging protocol so that stress and rest studies are sufficiently separated in time to allow optimum myocardium to background uptake ratios to differentiate between myocardial ischaemia and/or infarction. The biokinetic data for tetrofosmin suggest that no significant changes occur in myocardial distribution up to 180 minutes post injection. It is, therefore, necessary for two doses of the radiopharmaceutical and two separate studies to evaluate the myocardial status during stress and rest. This study assessed the differences between the 1 and 4 hour post injection SPET images obtained following peak exercise in 20 consecutively chosen patients. In addition, these images were compared to the rest images obtained on the following day after a second dose of the radiopharmaceutical was administered. In 4 patients, a one and four hour post injection study was also done during the rest phase. The results demonstrate significant changes in Tc-99m tetrofosmin distribution between the one hour and four hour post injection images. These differences are present during the stress as well as rest studies.

Effects of L-propionylcarnitine on ischemia-induced myocardial dysfunction in men with angina pectoris.

To identify the effect of L-propionylcarnitine (LPC) on ischemia, 31 fasting, untreated male patients with left coronary artery disease were studied during 2 identical pacing stress tests 45 minutes before (atrial pacing test I [APST I]) and 15 minutes after (APST II) administration of 15 mg/kg of LPC or placebo. Hemodynamic, metabolic, and nuclear angiographic variables were studied before, during, and for 10 minutes after pacing. After LPC administration, arterial total carnitine levels increased from 47 +/- 1.7 mumol/liter (control) to 730 +/- 30 mumol/liter. Hemodynamic and metabolic variables were comparable in LPC and placebo during APSI I, and reproducible in placebo during both tests. Although LPC did not affect myocardial oxygen demand and supply, it diminished myocardial ischemia, indicated by a significant 12% and 50% reduction in ST-segment depression and left ventricular end-diastolic pressure, respectively, during APST II. Moreover, during APST II, left ventricular ejection fraction increased by 18% (p < 0.05 vs APST I). Furthermore, LPC improved recovery of myocardial function after pacing, with a reduction in the time to peak filling and a 21% increase in both peak ejection and filling rates 10 minutes after pacing (all p < 0.05). Thus, LPC prevents ischemia-induced ventricular dysfunction, not by affecting the myocardial oxygen supply-demand ratio but as a result of its intrinsic metabolic actions, increasing pyruvate dehydrogenase activity and flux through the citric acid cycle. Because it is well tolerated, it may be a valuable alternative or addition to available antiischemic therapy.

Acute improvement of cardiac function with intravenous L-propionylcarnitine in humans.

As the myocardial carnitine content, a key control factor in myocardial oxidative metabolism and energy transfer, is reduced in heart failure, administration of L-propionylcarnitine (LPC), a potent analogue of L-carnitine, potentially may improve cardiac function, possibly through a positive inotropic effect. As its hemodynamic profile is unknown in humans, 32 fasting normotensive patients with coronary artery disease received either 15 mg/kg of LPC (n = 16) or vehicle (mannitol/acetate, n = 16) infused over 5 min. Hemodynamic, radionuclide [peak ejection and filling rates (PER and PFR, respectively)], and metabolic variables (myocardial O2, lactate, and carnitine uptake) were studied at baseline and 1, 3, 5, 10, 15, and 45 min postdrug. The baseline ejection fraction was depressed in LPC patients (40 +/- 3% vs. 48 +/- 4% in the vehicle group, p less than 0.05) as a result of a significant high incidence of previous infarctions. Immediately following LPC, the cardiac total carnitine uptake changed from 102 +/- 181 to 5,335 +/- 1,761 mumol/L (p less than 0.05). In both groups, left ventricular systolic and end-diastolic pressures increased significantly by 5 and 20%, respectively, during the first 5 min. In the vehicle group, contractility decreased by 5%, accompanied by a significant 11% fall in the stroke volume. In contrast, following LPC, isovolumetric contractility indices remained unaltered. Instead, both the PER and PFR improved by 16% at 45 min. Moreover, the cardiac output increased by 8%. LPC did not affect systemic or coronary hemodynamics. Lactate uptake increased by 42%, but myocardial O2 consumption did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Single-photon-emission computed tomography of the brain in the evaluation of cerebral lupus.

We sought to determine whether single-photon-emission computed tomography (SPECT) of the brain is useful for detecting abnormalities of regional cerebral blood flow in patients with cerebral lupus. Twenty lupus patients with clinical evidence of cerebral involvement underwent SPECT and CT scanning of the brain, as well as clinical, expert neurologic, and serologic evaluation. Fifteen patients (75%) had a clear regional cerebral hypoperfusion. Seven of 8 patients (88%) who were ultimately thought to have active cerebral lupus had abnormal SPECT scan findings, while 8 of 12 patients (67%) who were ultimately thought not to have active cerebral lupus had abnormal SPECT scan findings. There was no correlation of SPECT findings with CT scan results, overall disease activity, or serologic findings. Regional cerebral blood flow measured by SPECT is often abnormal in patients with active cerebral lupus, but is also frequently abnormal in lupus patients with neuropsychiatric symptoms not attributable to cerebral lupus activity.

Uterine radiation dose from open sources: the potential for underestimation.

The evaluation of the risk of radiation damage to the unborn child as the result of the administration of radionuclides remains a subject for discussion (Mountford 1989). Lack of information concerning the biodistribution of radiopharmaceuticals in the early stages of pregnancy, before organogenesis has occurred, has greatly restricted the objective assessment of fetal doses. Recent observations on the biodistribution of a therapeutic dose of sodium iodide 131 in a patient with an unsuspected early pregnancy lead us to suspect that current dose estimates with respect to uterine exposure (ARSAC 1988) may seriously underestimate the actual exposure of the developing fetus.

Potential pitfalls in computer tomography.

Some pseudotumours and pitfalls in computer tomography of the abdomen and the head are demonstrated. In abdominal CT the patient preparation is discussed.

Some pseudotumors and pitfalls in ultrasound.

A collection of pseudomasses and pitfalls in abdominal ultrasound are reviewed. This article discusses the way in which to avoid misinterpretation in these cases. Some anatomical variations and accidental configurations are mentioned.

Hippel-Lindau disease. A case history of one family.

This article describes the results of a prospective study in the 4 asymptomatic members of a family affected with Hippel-Lindau disease after the death of 2 patients and the surgical findings of the third. It stresses the multicentric and bilateral origin of renal cell carcinoma in Hippel-Lindau disease, usually combined with renal cortical cysts. The walls of these cysts often contain carcinoma cells. It is important that all relatives of a patient with the Hippel-Lindau disease are adequately screened.