Components of acquisition-to-acquisition variance in continuous arterial spin labelling (CASL) imaging.

Background: Images of perfusion estimates obtained with the continuous arterial spin labelling technique are characterized by variation between single acquisitions. Little is known about the spatial determinants of this variation during the acquisition process and their impact on voxel-by-voxel estimates of effects.

Results: We show here that the spatial patterns of covariance between voxels arising during the acquisition of these images uncover distinct mechanisms through which this variance arises: through variation in global perfusion levels; through the action of large vessels and other, less well characterized, large anatomical structures; and through the effect of noisy areas such as the edges of the brain.

Baseline brain perfusion and the serotonin transporter promoter polymorphism.

Background: The serotonin transporter length repeat polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene (SLC6A4) has been associated in healthy subjects with changes in basal perfusion levels in the limbic system and ventral prefrontal areas, regions involved in the pathophysiology of depression and anxiety, suggesting the existence of a neurobiological trait predisposing to these disorders. We reassess the findings of an increased baseline perfusion in the amygdala and ventral prefrontal areas in healthy carriers of the risk genotype in a much larger sample than in previous studies.

Methods: A cohort of 183 healthy European individuals underwent perfusion imaging with continuous arterial spin-labeling (CASL) while resting quietly in the scanner for 8 minutes.

Components of variance in brain perfusion and the design of studies of individual differences: the baseline study.

Simple baseline studies correlate average perfusion levels measured at rest with individual variables, or contrast subject groups as in case-control studies. In this methodological work, we summarize some formal properties of the design of these studies, and investigate the sources of variance that characterize data acquired with the arterial spin labeling technique, with the purpose of alerting users to the main sources of variation that determine background variance and affect the power of statistical tests. This design typology is characterized by two variance components: between acquisitions and between subjects.

Baseline brain perfusion and working memory capacity: a neuroimaging study.

Early studies of rest cerebral metabolism and perfusion reported no association with intellectual capacity. We revisit this issue using a larger sample (N=146) and a continuous arterial spin labeling technique to measure perfusion, and working memory capacity as a measure of intellectual capacity. In the cortex, working memory capacity correlated diffusely and negatively with perfusion.

Preoperative and postoperative quality of life in patients with familial adenomatous polyposis.

Purpose: This study was designed to prospectively examine functional outcome, quality of life, and patients' personal experiences and adjustment to functional changes during the first year after prophylactic surgery.

Methods: Twenty-one consecutive patients with familial adenomatous polyposis were examined before proctocolectomy (T0), on ileostomy reversal (T1), and 6 (T2) and 12 months (T3) after surgery by means of standardized questionnaires and interviews.

Results: Average physical and mental health declined profoundly after proctocolectomy, followed by a steady improvement after 6 and 12 months.