Comparison of the Detection Rate of Simulated Microcalcifications in Full-Field Digital Mammography, Digital Breast Tomosynthesis, and Synthetically Reconstructed 2-Dimensional Images Performed With 2 Different Digital X-ray Mammography Systems.

OBJECTIVE: The aim of this study was to compare the microcalcification detectability in an anthropomorphic phantom model regarding number, size, and shape in full-field digital mammography (FFDM), synthetically reconstructed 2-dimensional (Synthetic-2D) images, and digital breast tomosynthesis (DBT) performed with 2 different x-ray mammography systems. MATERIALS AND METHODS: Simulated microcalcifications of different numbers (0 to >39), sizes (diameter, 100-800 µm), and shapes (round vs heterogeneous) were scattered by random distribution on 50 film phantoms each divided in 4 quadrants. The FFDM and DBT x-rays were taken from each of these 50 films with both x-ray mammography systems (SenoClaire; GE Healthcare, Selenia Dimensions, Hologic) using an anthropomorphic scattering body and automatic exposure control. The resulting exposure factors were similar to a clinical setting. The synthetically reconstructed 2D images were generated automatically on both systems. All FFDM, Synthetic-2D, and DBT images were interpreted in randomized order and independently of each other by 6 radiologists using a structured questionnaire. RESULTS: The number categories of simulated microcalcifications were correctly evaluated in 55.3% of instances (quadrant by reader) in FFDM, 50.9% in the Synthetic-2D views, and 59.5% in DBT, summarized for 200 quadrants per reader for each Device A and B, respectively. Full-field digital mammography was superior to Synthetic-2D (mean difference, 4%; 95% confidence interval [CI], 2%-7%; P < 0.001), and DBT was superior to both FFDM (mean difference, 4%; 95% CI, 2%-7%; P = 0.002) and Synthetic-2D (mean difference, 9%; 95% CI, 6%-11%; P < 0.001). This trend was consistent in all subgroup analyses. The number of the smallest microcalcifications (100-399 µm) was correctly evaluated in 25.2% of the FFDM, in 14.2% for Synthetic-2D, and in 28.3% of the DBT images. Underestimations of the number of simulated microcalcifications were more common than overestimations. Regarding the size categories of simulated microcalcifications, the rates of correct assessments were in 45.4% of instances in FFDM, 39.9% in the Synthetic-2D views, and 43.6% in DBT, summarized for 200 quadrants per reader and both imaging devices. CONCLUSIONS: In the presented in vitro environment using an anthropomorphic phantom model, standard full-field digital x-ray mammography was superior to synthetically reconstructed 2-dimensional images in the detection of simulated microcalcifications. In view of these results, it is questionable whether Synthetic-2D images can replace FFDM in clinical examinations at the present time. Further investigations are needed to assess the clinical impact of the in vitro results.

The impact of stroke on cognitive processing - a prospective event-related potential study.

BACKGROUND AND PURPOSE: Stroke is often associated with cognitive decline which can be evaluated by event-related potentials (ERP). So far, only little is known about the impact of stroke on ERP. The aim of this prospective study was to follow-up ERP latencies in stroke patients and to evaluate the influence of sex, vascular territory of stroke, reinfarction, and secondary prevention (acetylsalicylic acid versus piracetam). METHODS: Visually evoked ERP were recorded in 563 stroke patients at baseline (i.e., within four weeks after stroke), after 12 months, and after 24 months. The latencies of the P2, N2, and P3 components were assessed and compared between different subgroups. RESULTS: The P3 latency is initially more increased in female stroke patients, but shows a better recovery in women compared to men. A secondary prevention with piracetam leads to a significantly better recovery of ERP latencies than a treatment with acetylsalicylic acid. Data suggests a better recovery of left hemispheric infarction compared to right hemispheric infarction. Patients, who suffered another stroke during the follow-up period, showed a prolongation of P3 latency, suggesting an increased P3 latency to be associated with reinfarction. CONCLUSIONS: Our results suggest that ERP measurement is an appropriate method for diagnosis and follow-up of cognitive changes after ischemic stroke. In particular the P3 component is an indicator for patients at risk for reinfarction.

The influence of fluid intake on stroke recurrence--a prospective study.

BACKGROUND: Recommended fluid intake is regarded as an important factor for stroke prevention. In mass media, drinking of at least 2000 ml water per day is recommended for any condition. However, no prospective trials are available which examined the impact of the amount of daily fluid intake on primary stroke prevention or on stroke recurrence. We performed a prospective study evaluating the daily fluid intake over a period of two years in stroke patients. METHODS: Patients (n=465) with a complete stroke (i.e., proven ischaemic cerebral infarction) were followed for two years with a regular visit every three months. At every visit the average daily amount of fluid intake was evaluated by a drinking diary. Patients had to protocol all kinds of fluid they were drinking during the day for a whole week. They were divided into two groups: daily intake of more and of less than 2000 ml. The rate of primary endpoint (stroke including transient ischaemic attack, myocardial infarction, or death from any cause) and of secondary endpoint (stroke) was calculated for the two groups. In addition, haemorheological parameters such as platelet reactivity, erythrocyte aggregation, and osmolarity were measured at every visit. RESULTS: The mean observation period was 17 months. In this period, the patients with recommended fluid intake (mean amount 2427 ml) had a primary event rate of 12.3% whereas the patients with the low fluid intake (mean amount 1625 ml) had a primary event rate of 16.8%. The Kaplan-Meier analysis revealed a significantly better outcome of the patient group with recommended fluid intake with respect to the primary endpoint (p<0.013) and to the secondary endpoint (p<0.007). We observed a lower platelet reactivity in the patient group with recommended fluid intake as the only significant haemorheological factor influenced by the fluid intake. We observed no association between the amount of fluid intake and conventional vascular risk factors except a higher fluid intake in smokers. CONCLUSIONS: Our data suggests that a fluid intake of more than 2000 ml per day might by a protective factor in secondary stroke prevention. A recommended fluid intake is associated with a lower platelet reactivity. No other haemorheological parameters were affected by the amount of fluid intake. However, advising patients after stroke on how much fluid they should drink is also influenced by other factors such as renal and cardiac function.