Johan Virhammar
Epidemiologic studies indicate that idiopathic normal pressure hydrocephalus (iNPH) is a much more common disease in the elderly population than previously believed.1 Even though iNPH is increasingly recognized, the number of shunt implantations performed is far lower than the occurrence of the disease. For decades, reliable tests that can aid in the diagnosis of iNPH and predict outcome after shunt surgery have been sought. The most common tests used in the clinical work-up of patients with iNPH are invasive and time-consuming. With hopes of finding a reliable, noninvasive, and fast diagnostic and predictive test, our research group started investigating patients with iNPH using pseudocontinuous arterial spin-labeling (ASL) around 2013.
Previous perfusion studies in iNPH have reported reduced perfusion in the frontal cortex, periventricular white matter, basal ganglia, thalamus, and cerebellum in patients with iNPH.2–5 These studies used methods that require the administration of a radioactive tracer or a contrast agent, and often methods that expose the patient to ionizing radiation. Compared with these methods, ASL seems appealing, as the sequence is rapid, noninvasive, and without ionizing radiation.
In our study, we were able to replicate the findings of previous perfusion studies using pseudocontinuous ASL. Cerebral perfusion was decreased in the periventricular white matter, basal ganglia, and thalamus in patients with iNPH compared with age- and sex-matched healthy controls. However, even if there were significant differences at a group level, it is still uncertain