The impact of β-amyloid positron emission tomography on the diagnostic and treatment decisions of dementia experts

Aim: Amyloid positron emission tomography (aPET) measurement of Alzheimer's disease (AD) pathology could improve the accurate diagnosis of cognitive disorders. Appropriate use criteria recommend that only dementia experts order aPET. Materials & methods: We surveyed 145 dementia experts about their current approaches to evaluation and treatment and the likely influence of aPET. Results: Experts expected aPET to alter diagnostic procedures and patient management and also increase diagnostic certainty. They anticipated confirming AD or altering pharmacological treatment following positive results more than excluding AD following negative results. Experts familiar with aPET reported changes that were more consistent with appropriate use criteria and published evidence. Conclusions: Knowledge about aPET strongly influenced effects on diagnostic certainty and changed clinical practice. Dementia experts may need additional training to achieve optimal benefit from aPET.

Excretion kinetics of ifosfamide side-chain metabolites in children on continuous and short-term infusion

Ifosfamide (IFO) requires metabolic activation by hydroxylation of the ring system to exert cytotoxic activity. A second metabolic pathway produces the cytostatically inactive metabolites 2-dechloroethyl-ifosfamide (2-D-IFO) and 3-dechloroethyl-ifosfamide (3-D-IFO) under release of chloroacetaldehyde. This side-chain metabolism has been suggested to be involved in CNS- and renal toxicity. The total urinary excretion of ifosfamide and its metabolites was investigated during 23 cycles in 22 children at doses ranging from 400 mg/m2 to 3 g/m2. The kinetics of the excretion were compared following short-term and continuous ifosfamide infusion at a dosage of 3 g/m2. IFO and side-chain metabolites were analyzed by gas chromatography, the active metabolites by indirect determination of acrolein (ACR) and IFO mustard (IFO-M) with the NBP test. 59+/-15% of the applied dose could be recovered in the urine, 23+/-9% as unmetabolized IFO. The main metabolite was 3-D-IFO (14+/-4%) followed by isophosphoramide mustard (IFO-M) (13+/-4%) and 2-D-IFO (8+/-3%). Neither the total amount recovered nor the excretion kinetics of ifosfamide and side-chain metabolites showed obvious schedule dependency. The excretion kinetics of side-chain metabolites as well as unmetabolized IFO were nearly superimposable on short-term and continuous infusion. Even after 1-hour infusion there was a lag of 3 - 6 hours until dechloroethylation became relevant. Therefore, differences in toxicity and efficacy cannot be explained by an influence of the application time on the metabolic profile of ifosfamide.