Anatomic basis of amygdaloid and hippocampal volume measurement by magnetic resonance imaging

Abstract

Both the amygdala and the hippocampus are involved in the pathogenesis of a number of neurologic conditions, including temporal lobe epilepsy, postanoxic amnesia, and Alzheimer's disease. To enhance the investigation and management of patients with these disorders, we developed a protocol to measure the volumes of the amygdala and as much of the hippocampus as possible (approximately 90 to 95%) using high-resolution MRI. We present the anatomic basis of these two protocols and our results in normal control subjects. These volumetric studies of the amygdala may clarify the role of this structure in the pathogenesis of temporal lobe epilepsy.

MR-based in vivo hippocampal volumetrics: 1. Review of methodologies currently employed

“…Of those who do provide sufficient detail, the majority report using images reformatted perpendicularly to the long axis of the hippocampal formation. 56 A substantial number of protocols use different acquisition sequences (either perpendicular to the AC-PC line 25,94,84 or the Sylvian fissure 3,20 ), but do not reformat their images, and a very small number of studies employ head-tilt protocols. [95][96][97] 3D imaging techniques allow researchers to save valuable scan time by eliminating the need for pilot scans needed for consistent positioning of images based on internal landmarks, and accomplishing this after the scan using multiplanar image reconstruction capabilities.…”

“…Whereas some protocols include the alveus in their conception of the hippocampus, 20,46,106 others choose to ignore the alveus. 81 Strictly speaking, the alveus is a white matter tract containing axons from hippocampal, subicular, and septal neurons.…”

“…Some researchers, such as Shenton et al, 54 measured the amygdala-hippocampal complex, whereas others reliably differentiated between amygdala and hippocampus. 20,21,55 Of the protocols in this database, 80% attempted to measure as much of the hippocampus as they could, and included the head and body in their measurements. Only a small minority of these studies excluded the tail.…”

“…These protocols have varying anatomical guidelines, which are summarized in Table 1. The protocol of Jack et al, 53 which has been revised in 1994, 56 and that of Watson et al protocol 20 are the most popular and are reported to have been used in 31 studies each. The protocols of Soininen et al 55 and Cook et al 21 are two other important and popular ones, which are also used frequently.…”

“…Magnetic resonance (MR)-based in vivo measurement of hippocampal volume is an accepted technique, which has been performed in the aged 1 and healthy subjects, 2 and has revealed a number of structural abnormalities in a variety of neurological and psychiatric disorders, such as temporal lobe epilepsy, 3 Huntington's disease, 4 Turner's syndrome, 5 Cushing's disease, 6 Down's syndrome, 7 Alzheimer's disease (AD), 8 mild cognitive impairment, 9 schizophrenia, 10 major depression (MD), 11 bipolar disorder, 12 post-traumatic stress disorder (PTSD), 13 borderline personality disorder, 14 chronic alcoholism, 15 obsessive-compulsive disorder, 16 and panic disorder. 17 The MR-derived hippocampal volumetric technique has demonstrated good validity and reproducibility, [18][19][20] and accuracy of the measurements has been shown by MRI volumetric measurement of phantoms with a known volume. 18,21 However, studies on hippocampal volume in neuropsychiatric disorders are inconclusive and do not always provide consistent results.…”