Sonographic characteristics of the cavum velum interpositum.
OBJECTIVE
Differential considerations for pineal region CSF collections include both true cysts and normal cystlike anatomic variations. Our purpose was to determine the sonographic characteristics of pineal region fluid spaces that reflect the presence of a normal persistent cavum velum interpositum (CVI).


METHODS
Eighteen neonates and infants who had sonographic findings of "cysts" in the pineal region were examined prospectively with conventional sonography and color Doppler sonography to evaluate the shape of the fluid collection and its anatomic relationship with the color-coded internal cerebral veins. Subsequent MR images were obtained in eight of these infants to determine the exact nature of the cystlike collections.


RESULTS
The cystlike spaces in the pineal region were of an inverted helmet shape in 14 subjects and roundish in four. All were situated inferior or slightly anteroinferior to the splenium of the corpus callosum and 2.5 to 4 mm away from the quadrigeminal plate. The internal cerebral veins were either inferior (n = 12) or inferolateral (n = 6) to the cystlike spaces at sonography. Subsequent MR studies confirmed eight of these cystlike spaces to be the posterior portion of the CVI.


CONCLUSIONS
The CVI may appear as a cyst in the pineal region on neonatal sonograms. Usually, it has a characteristic inverted helmet shape and is situated beneath the fornices and above the internal cerebral veins.
Chen
C Y
CY
Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China.
Chen
F H
FH
Lee
C C
CC
Lee
K W
KW
Hsiao
H S
HS
D001927:Brain Diseases / Q000175:diagnosis; D002550:Cerebral Veins / Q000000981:diagnostic imaging / Q000473:pathology; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging* / Q000473:pathology; D002555:Cerebrospinal Fluid / Q000378:metabolism; D003560:Cysts / Q000175:diagnosis; D006801:Humans; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D010870:Pineal Gland / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D012688:Septum Pellucidum / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography; D018615:Ultrasonography, Doppler, Color