Aneurysm of the inferior vena cava: case report.

Venous aneurysms are uncommon. Despite their infrequency, venous aneurysms can present with significant clinical complications such as thrombosis, pulmonary embolism, and death. In this report, we present the case of a thrombosed inferior vena cava aneurysm discovered in a 16-year-old male who had deep vein thrombosis of the right lower extremity. Thrombosis of the inferior vena cava is uncommon in the pediatric population. Therefore, congenital abnormalities such as an inferior vena cava aneurysm should be considered when evaluating pediatric patients who present with deep vein thrombosis.

Four-dimensional spectral-spatial imaging using projection reconstruction.

An n-dimensional (n-D) filtered backprojection image reconstruction algorithm has been developed and used in the reconstruction of 4-D spectral-spatial magnetic resonance imaging (MRI) data. The algorithm uses n-1 successive stages of 2-D filtered backprojection to reconstruct an n-D image. This approach results in a reduction in computational time on the order of N(n-2) relative to the single-stage technique, where N(n) is the number of elements in an n-D image. The authors describe implementation of the algorithm, including digital filtering and sampling requirements. Images obtained from simulated data are presented to illustrate the accuracy and potential utility of the technique.

Sources of the increased longitudinal relaxation rates observed in melanotic melanoma. An in vitro study of synthetic melanins.

Researchers have suggested that the increased longitudinal relaxation rates (1/T1) of solvent water protons often found in melanoma result either from the paramagnetism of stable free radicals occurring in melanin or from that of methemoglobin in nonacute hemorrhagic regions of the tumor. However, field-cycling relaxometry and model solutions of synthetic melanin produced data which show that free radicals in melanin do not contribute significantly to 1/T1; instead, aggregation of melanin into macromolecular particles and binding of biologically-common paramagnetic metal ions (ie Fe3+, Mn2+, and Cu2+) to melanin effectively do increase 1/T1. These data have been combined with published histochemical data on melanin-containing tissues, while disregarding any additional effect related to hemorrhage. The result indicates that in melanoma the expected contribution of melanin-bound Fe3+ to 1/T1, at typical imaging fields, predominates under estimated in vivo conditions; furthermore, the total contribution from all sources, specifically due to the presence of melanin, is sufficient to account for reported measurements of 1/T1 in melanoma. Comparing the latter results with published data on T1 relaxation in model solutions of methemoglobin suggests that co-existing regions of nonacute microhemorrhage also may contribute significantly to 1/T1 under certain conditions. Finally, the implications for 1/T2 of melanin occurring in vivo within discrete melanosomes is discussed.