Growing evidence suggests that a history of sport concussion may lead to long-term changes in brain physiology, with cerebral blood flow (CBF) being particularly sensitive to injury. However, it is unknown whether these changes are sex specific. The goal of this study was to evaluate sex differences in CBF of asymptomatic athletes, with and without a history of concussion (HOC) using arterial spin labeling (ASL). Scans were acquired for 122 athletes, including those without HOC (33 male, 33 female) and those with HOC (28 male, 28 female). Males with HOC had lower CBF bilaterally than males without HOC, seen predominantly in the temporal lobes. In contrast, females with HOC showed no significant differences relative to females without HOC, although they had significantly higher variability in temporal CBF values compared with males with HOC. Additional analyses within the HOC groups found that females with multiple concussion had lower CBF posteriorly compared with those with a single concussion, whereas males showed no significant effects. This study provides the first evidence of sex differences in CBF associated with HOC.

Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels with stenosis of different degrees and shapes. The results show that dispersion is more pronounced under resting conditions than during hyperemia. Stenosis leads to a reduction of dispersion. In consequence, dispersion results in a systematic MBF underestimation between -0.4% and -9.3%. The relative MBF error depends not only on the dispersion but also on the actual MBF itself. Since MBF under rest is more underestimated than under stress, myocardial perfusion reserve is overestimated between 0.1% and 4.5%. Considering other sources of errors in myocardial perfusion MRI, systematic errors of MBF by bolus dispersion are relatively small.

A case with an intense accumulation of 57Co-bleomycin in lymph node metastases of malignant melanoma in the mediastinum as a casual finding is reported. The patient had undergone a 57Co-bleomycin scintigraphy because of a peripheral lesion on the chest X-ray, in which a pathological diagnosis was impossible to obtain. This lesion showed no uptake of the radiopharmaceutical.

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