Volumetric data of normal nucleus accumbens from magnetic resonance imaging scans.

Backgrounds and aims: The nucleus accumbens (AcN) belongs to the ventral striatum and it is involved in several neuropsychiatric disorders. In contrast to other subcortical structures, the number of morphometric studies that concern the healthy nucleus is limited. This study aims to investigate the normal volumetric data of the AcN as derived from a large number of manually segmented magnetic resonance imaging (MRI) scans. Methods: The measurements were performed in 106 MRI scans of healthy adults. The resulting volumes have been analyzed for differences related to hemisphere, sex and age. Results: The mean AcN volume was estimated at 473.3 mm3 (SD=±106.8). A slight interhemispheric difference in favor of the left side was found, the value of which was, however, within the limits of the method error. There were no sexual dimorphism signs concerning both the raw and the normalized volumes. A negative correlation between volumes and age was observed only in males. Conclusions: The study provides normal volumetric data of the AcN, useful in the conduct of comparative imaging and post-mortem studies in pathological conditions.

In vivo estimation of normal amygdala volume from structural MRI scans with anatomical-based segmentation.

PURPOSE: Literature includes a number of studies using structural MRI (sMRI) to determine the volume of the amygdala, which is modified in various pathologic conditions. The reported values vary widely mainly because of different anatomical approaches to the complex. This study aims at estimating of the normal amygdala volume from sMRI scans using a recent anatomical definition described in a study based on post-mortem material. METHODS: The amygdala volume has been calculated in 106 healthy subjects, using sMRI and anatomical-based segmentation. The resulting volumes have been analyzed for differences related to hemisphere, sex, and age. RESULTS: The mean amygdalar volume was estimated at 1.42 cm3. The mean right amygdala volume has been found larger than the left, but the difference for the raw values was within the limits of the method error. No intersexual differences or age-related alterations have been observed. CONCLUSION: The study provides a method for determining the boundaries of the amygdala in sMRI scans based on recent anatomical considerations and an estimation of the mean normal amygdala volume from a quite large number of scans for future use in comparative studies.