Investigation of patent foramen ovale as a mechanism for brain metastasis in patients without prior lung involvement.

PURPOSE: The mechanisms of brain metastasis are incompletely understood. Circulating tumor cells travel to the right heart and through the pulmonary circulation, where they may become lung metastases, and can circulate further to the left heart and brain. In patients who develop brain metastases without lung involvement, we hypothesized that cancer cells may travel directly from the right atrium to left atrium via a patent foramen ovale (PFO), akin to paradoxical embolism. If the prevalence of PFO is greater in these individuals compared to the general population (20-30%), PFO may play a role in brain metastasis, and prophylactic closure may provide benefit. Accordingly, we investigated the prevalence of PFO in patients with brain metastases without prior lung involvement. METHODS: We prospectively identified patients with brain metastases from a non-lung primary cancer with no preceding or concurrent lung involvement. Nine eligible participants underwent a transcranial Doppler study with intravenous agitated saline to assess for PFO. RESULTS: Among nine participants, primary cancers were breast (n = 6), upper gastrointestinal (n = 2), and thyroid (n = 1). A positive bubble study was identified in 2/9 (22.2%) participants: one female with breast cancer and one male with duodenal adenocarcinoma. No participants developed lung metastases on subsequent chest imaging. CONCLUSION: In this prospective pilot study, we found a similar prevalence of PFO in patients who developed brain metastases without preceding lung involvement compared to estimates for the general population. Through a larger study is needed, the development of brain metastases in these individuals may primarily reflect tumor-specific biological factors diecting metastasis organotropism.

Coronary arteriovenous fistula as a cause for reversible thallium-201 perfusion defect.

Exercise 201Tl SPECT imaging has become routinely accepted and utilized as a major screening test for atherosclerotic coronary artery disease. In appropriate clinical situations, an abnormal 201Tl study usually will require a subsequent coronary angiogram to confirm the presence of an abnormality and to define its pathologic anatomy. Although most reversible thallium defects will prove to be secondary to significant coronary artery atherosclerosis, congenital coronary or cardiac anomalies can occasionally be responsible, and it is useful to be aware of these, particularly in the evaluation of relatively young symptomatic patients. We report, for the first time, a coronary arteriovenous fistula as the cause for an exercise-induced reversible 201Tl perfusion abnormality.

Uptake of lead by vegetable foodstuffs during cooking.

Uptake of Pb by foodstuffs during cooking has been identified as an additional potential source of human exposure to Pb. Vegetables and rice cooked in water containing Pb may adsorb up to 80% of the Pb in the water. The amount of Pb adsorbed was dependent upon the concentration of Pb in the water, type of vegetable, water hardness, salting of the water, duration of cooking and the available surface-area of the vegetables. Substantial deposition of Pb also occurred on the surfaces of the saucepan itself (Al greater than enamel greater than Teflon), with subsequent desorption under certain cooking conditions. During tea-making, the concentration of Pb in water was reduced by 30-40% due to adsorption of Pb by the tea-bags. The dietary significance of the adsorption of Pb by foodstuffs during cooking as an additional source of human Pb uptake is assessed.