Delineation of intermammillary relationships using magnetic resonance imaging

Purpose: No study has investigated intermammillary relationships using neuroimaging modalities. This study aimed to explore them using magnetic resonance imaging (MRI). Materials: and Methods: We enrolled 72 patients who underwent conventional MRI examinations followed by constructive interference steady-state sequence in the coronal plane. The intermammillary distances (IMDs) were measured at the uppermost level of the intermammillary gap (IMD upp ) and the lowest level (IMD low ) of the mammillary bodies (MBs). Results: : MBs with varying morphologies were consistently delineated. The appearance of both MBs could be classified into four patterns based on the size and relative levels, with the symmetrical type being the most common. Intermammillary relationships exhibited five patterns. In 69%, the IMD upp was discernable and measured 0.7±0.4 mm, while it was not discernible in 31% due to the presence of intermammillary connection and adhesion. The age distribution did not differ between populations with and without discernible IMD upp . The IMD low was measured 4.4±0.9 mm. Although the IMD low was not significantly different between both sexes, it was longer in subjects in their 70s. Conclusions: : Intermammillary relationships show variable morphologies with gaps formed between both MBs. The IMD low may become more evident in association with age-related increase in the width of the third ventricle and atrophy of the MBs.