Biomedical subjects

P Vainio

Publications and source records attributed to P Vainio.

93 records · Page 6Linked to original sources

PubMedDate not supplied

MRI of the hippocampus in Alzheimer's disease: sensitivity, specificity, and analysis of the incorrectly classified subjects.

In this study, magnetic resonance imaging (MRI) of the hippocampus for the diagnosis of early Alzheimer's disease (AD) is evaluated. We measured hippocampal volumes and the area of the medial hippocampus with a 1.5 T MR imager in 160 subjects: 55 patients with probable AD according to the NINCDS-ADRDA criteria, 43 subjects fulfilling the NIMH criteria of age-associated memory impairment (AAMI), 42 cognitively normal elderly controls, and 20 controls younger than 50 years. Three methods for normalization were compared. The hippocampi were atrophied in the AD patients, but not in the AAMI subjects or the elderly controls. There was no significant correlation between hippocampal volumes and age in the nondemented subjects. The discrimination based on volumetry resulted in an overall correct classification of 92% of AD patients vs. nondemented elderly subjects, whereas discrimination based on hippocampal area was less accurate, producing a correct classification in 80% of the subjects. We conclude that the hippocampus as assessed by MRI volumetry is atrophied early in AD, and spared by aging or AAMI. A brief critical review of previous studies is in concordance with the presented data: all the previous studies that have used volumetry, have similarly ended up with a good classification, whereas simpler or subjective measurements, subject to various sources of bias, have produced most variable results.

Aged↗

PubMedDate not supplied

Cerebral benzodiazepine receptor binding and distribution in generalized anxiety disorder: a fractal analysis.

Data obtained from animal and human brain imaging studies indicate that frontal cortex and medial temporal lobe are involved in experiencing and controlling fear and anxiety. We tested the hypothesis that benzodiazepine receptor binding is decreased in the left temporal pole and increased in the right prefrontal area among patients suffering from anxiety. We studied 10 drug-naive female patients with generalized anxiety disorder (GAD) and 10 age- and gender-matched healthy controls with MRI and with SPET by using a new (123)I-labelled specific benzodiazepine receptor radioligand, NNC 13-8241. Blindly analyzed results showed that the benzodiazepine receptor binding of [(123)I]NNC 13-8241 was significantly decreased in the left temporal pole among patients with GAD when compared with age- and sex-matched healthy controls. This hemispheric asymmetry was studied further with a fractal analysis of the SPET images. The fractal dimension of the left hemispheric benzodiazepine receptor binding in patients with GAD was significantly higher than that of controls (1.28 +/- 0.09 and 1.17 +/- 0.07, respectively), whereas the intercept was decreased by 43 +/- 23% reflecting more homogeneous cerebral benzodiazepine receptor density distribution in patients with GAD. The finding is analogous to the decreased heterogeneity of myocardial blood flow observed in patients with ischemic heart disease. The results are consistent with the general hypothesis that high regional heterogeneity of perfusion, metabolism and receptor density is necessary to maintain adaptation ability in the living organism.

Adult↗

PubMedDate not supplied

Repeated 3D coronary MR angiography with navigator echo gating: technical quality and consistency of image interpretation.

The purpose of this study was to evaluate the technical quality of 3D coronary MR angiography (CMRA) with navigator echo and the consistency of image interpretation in repeated imaging sessions. Fourteen subjects underwent CMRA, 10 of whom were imaged twice. The coronary arteries (96 segments) were analyzed twice for hemodynamically significant stenoses. Signal-to-noise and contrast-to-noise ratios varied considerably between the two imagings. Fat saturation was poor or satisfactory in 37%; in 15% of the slabs, the severity of artifacts was moderate; and the overall quality was good to excellent in only 42% of the imagings. The intraobserver reproducibility was good (kappa = 0.54), but the consistency of interpretation for repeated CMRA was only satisfactory (kappa = 0.43). Sensitivities of 84 and 84% and specificities of 70 and 62% were obtained for the two readings. Although the reproducibility of image reading is good, 3D CMRA with navigator echo provides only fair technical consistency, and the frequently compromised image quality impairs the clinical utility of this technique.

Adult↗