The objectives of this thesis were to study the magnitude of the risk of venous thrombosis (VT) in the general population, and to determine clinical and biochemical factors that influence this risk... Show moreThe objectives of this thesis were to study the magnitude of the risk of venous thrombosis (VT) in the general population, and to determine clinical and biochemical factors that influence this risk. We examined this separately for first and for recurrent thrombotic events: TROL, a Norwegian prospective follow-up study in the population, in which we counted patients with a 1st event of VT and LETS, a follow-up of a Dutch cohort of 474 consecutive patients with a 1st objectively confirmed VT. The incidence rates for all first VT events was 1.43 per 1000 person-years and increased exponentially with age, and were slightly higher in women than in men. Patients with pre-existing inflammation or anticardiolipin antibodies did not have any increased risk for subsequent VT disease. We found that high levels of homocysteine are at most a weak risk factor for subsequent VT. In the LETS-study, the rate of VT recurrence was 25.9 per 1000 patient-years. The risk of recurrence was 2.7 times higher in men than in women. Recurrence risk was increased if the initial VT was unprovoked or if women used oral contraceptives during follow-up. Surprisingly, there was no clear relation between recurrence risk and the presence of thrombophilia Show less
Neuropsychiatric systemic lupus erythematosus (NPSLE) is a rheumatologic disorder causing neurologic, psychiatric and/or psychologic symptoms. The most important clinical problems are the aspecific... Show moreNeuropsychiatric systemic lupus erythematosus (NPSLE) is a rheumatologic disorder causing neurologic, psychiatric and/or psychologic symptoms. The most important clinical problems are the aspecific nature of signs and symptoms, the limited knowledge on pathogenesis and the absence of a diagnostic gold standard. Magnetic resonance imaging (MRI) is considered the most important imaging modality of the brain in NPSLE patients. Abnormalities visible on conventional MRI appear anywhere in the brain, and may normalize, stabilize or increase with loss of brain parenchyma. Apart from conventional MRI sequences, in this thesis advanced MRI techniques such as magnetization transfer imaging (MTI) were also applied, which are more sensitive to microscopic brain damage invisible to the human eye. Microscopic brain damage in NPSLE appears mostly in the cortical gray matter and is associated with the presence of anticardiolipin antibodies. The final brain damage, as observed using different MRI techniques, consists of neuronal and axonal damage, atrophy, demyelination and gliosis. Changes in the total amount of microscopic brain damage as detected by MTI correlate with changes in clinical status. This thesis contributes to the knowledge on the pathogenesis of NPSLE, and illustrates that advanced and conventional radiological techniques can be helpful in making diagnostic and therapeutic decisions. Show less
