339 Normal Infant Brain Anatomy: Correlated Real-Time Sonograms and Brain Specimens Asterios Pigadas 1 An investigation of the identifiable real-time sonographic features of the normal Joseph R. Thompson 1 infant brain in the horizontal, coronal, inclined coronal, and midsagittal planes was Gerald L. Grube2 undertaken. Correlations were made of sonograms of intact brains in vitro, correspond­ ing brain sections, and sonograms in vivo. A large number of anatomic structures could be consistently depicted including cisterns, fissures, falx cerebri, tentorium cerebelli, ventricles, brainstem, cerebellum, basal ganglia, thalami, and corpus callosum. Pulsa­ tions of intracranial arteries, visible by real-time sonography, were of considerable help in identifying various structures. The investigation provides a reference of sonographic anatomy of the brain displayed in four clinically useful imaging planes. Early investigators of diagnosti c sonography were faced with th e probl ems of small-aperture unfocused transducers. In 1967, White et al. [1] summari zed these problems. In 1972, Kossoff and Garrett [2] reported intracrani al detail in fetal echograms using a weakl y focused 2 MHz transducer. They subsequently published a sonographic atl as of th e normal brain of infants using a focused 3 MHz transducer-contact C.A.L. echoscope [3]. McRae [4] and White [5], how­ ever, questioned th eir ability to identify those intracranial structures. In 1976 , Heimberger et al. [6], using large-aperture f oc us ~9 transducers, managed to display the outlines of th e th alamus, internal capsule, and substanti a ni gra in isolated excised brains. Recently Johnson et al. [7] showed sonographic anatomy in the axial pl ane and examples of intraventric ul ar hemorrhage in hi gh ri sk infants using B-mode contact transducers. The advent of versatil e real-time transducers has stimulated us to do more detailed imaging in several pl anes to establi sh a basic anatomy for use in clinical work. Real-time as opposed to stati c scanning was chosen because: 1. Recognizabl e pulsati ons of th e intracrani al vessels within fi ssures and cisterns and of the choroid pl exuses within the ventric les provides easier identi­ Received October 26. 1979; accepted after revision Febru ary 10, 1981. fication of these structures. Presented at the annual meetings of the Amer­ 2 . The real-time probe can be easil y maneuve red so th at the ultrasonic beam ican Insti tute of Ullrasound in Medicine, Montreal, is perpendicular to the intracranial structure under stu dy, th erefore receiving August 1979 and the Western Neuroradiological stronger reflecting echoes for better images. Sociely. Carm el, Ca lifornia, October 1979. Skolnick et al. [8 ] used a servo-controlled real-time scanner to detect dilated ' Deparlment of Radiati on Sciences, Secti on of Neuroradiology, Lorn a Linda Universi ty School of ventricles and correlated th e findings with computed tomography. We th ought it Medic ine, Lorn a Linda, CA 92350. Address reprint would be more useful to correlate real-time sonography and anatomic secti ons, requests to J . R. Thompson. in pl anes avail abl e for c linical examinati on. 2Department of Radiation Sciences, Section of Diagnosti c Ullrasound, Lorn a Li nda University School of Medicine, Lorn a Linda, CA 92350. This paper appears in the July / August 1981 Materals and Methods issue of AJNR and the October 1981 issue of AJR. The sonographic examinati ons were performed by using either a linear phased array AJNR 2:339-344, July / AU9ust 1981 0 0 195- 6 108/ 8 1/ 0204 - 0339 $00.00 transducer operating at 2.25 MHz and d isplaying 84 fan-shaped images at a frame rate © American Roentgen Ray Society of 30 / sec (Vari an V-3000), or an annular array transducer operating at 2.25 M Hz ± 15% 340 PIGADAS ET AL AJNR:2, July/ August 1981 Fig. 1.- Transducer placemenl for multiplanar imaging. A B A B c Fig. 2.-Horizontal plane at level of c hiasmatic c istern. A, In vitro real­ Ten = tentorium. Optic chiasm (black arrow); aqueducl of Sylvius (white time sonogram. B , Anatomic sectio n . C, In vivo. CC = chiasmati c c istern ; Int arrow); temporal horn (arrowhead). F = interh emispheric fi ssure; Syl F = sylvian fissure. M es = mesencephalon; and displaying 24 0 angle sector im ages at a selectable frame rate (Varian V-3000) was placed over the temporal squama for the of 1 or 12 / sec (Xerox 1505-4). horizontal planes and over the anterior fontanelle for the coronal, Three excised brain specimens were fi xed in formalin for 2 weeks inclined coronal, and midsagittal pl anes (fig. 1). Adequate ultrasonic and th en immersed in tap water. Care was taken to exclude air gel was appli ed between th e probe and skin for optimal acoustical bubbles from th e fi eld of view. Th e probe (Xerox 1505-4) was then coupling. No sedati on or anesth esia was necessary. Postprandial placed over th e temporal lobe and serial images were obtained in scanning or the use of a pacifier was adequate to obtain optimal th e hori zontal plane at 1 cm increments from the level of the lower im ages. All real-time sonograms were displayed on a vid eo screen cerebellum to th e high convexities of the cerebrum. For th e next and permanent records were made on Polaroid film and video tape. specimen, th e probe was pl aced in a position assumed to simu late th e anteri or fontanelle and seri al 1 c m images were obtained in the coronal plane. For the third specimen, th e transducer was placed Horizontal Plane in the position of th e anterior fontanell e and th e beam was directed toward the fourth ventricle giving a modified coronal im age (inclined Level of the Chiasmatic Cistern coronal plane). Fin all y, images were obtained with th e beam di­ The chiasmatic (suprasell ar) c istern is shown as a penta­ rected in the midsagittal plane. After the in vitro scanning was gonal, strongly echogenic structure in the center of the completed, the specimens were sectioned in the corresponding planes. image, with the similarly echogenic interhemispheric and Fifteen normal infants aged up to 15 months (average, 5 months) Sylvian fissures originating from the anterior and both lateral were also examined. Each had a normal CT study. The probe corners of the pentagon (fig. 2). Posteriorly, the circumme- AJNR:2. July / August 1981 INFANT CRANIAL ANATOMY 3 41 A B c Fi g. 3.-Hori zontal plane at level of cerebral pedunc les. A, In vitro. B, ventri cle; Int F = interhemispheric fi ssure. Choroid plexus of temporal horn Anatomic secti on. C, In vivo. AC = ambient cistern; Cer V = cerebell ar ( arro whead); aqueduc t ( arrow ). vermis; Cir S = circ ular sul cus; qc = quadri geminal cistern; 3 = third A B c Fi g . 4 .-Horizontal plane at level of thalami . A , In vitro. B, Anatomic Cir S = circ ul ar sulcus. Fornix ("); corpus call osum (long arrow) ; anterior sec ti on. C, In vivo. T = trigone; Tha = th alamus; vgc = ve in o f Galen c istern ; horn s ( short arrows ). sencephalic cisterns are continuous with the posterior cor­ can be seen to be pulsating within th e interpeduncul ar ners of the c isternal pentagon and outline a V-shaped ane­ c istern . choic structure, the mesencephalon. Pul sati ons are seen within the Sylvian, in te rhemispheri c , In the center of the pentagon, a low-amplitude-echo struc­ and circ ummesencephali c c istern s from th e middle cerebral , ture is constantly seen and represents the optic chiasm. anteri or cerebral, and circ ummesencephalic arteri es, re­ Th e relatively hypoechoic optic c hiasm appears to be di­ spectively. Posteri orl y, th e low amplitude echogeni c cere­ vided by a thin midline linear echogenic structure which can bellum is outlined by obliquely ori ented echoes representing be shown to be the anterior inferior part of third ventricle. th e leaves of th e tentorium . Th e frontal and temporal lobes Immediately ventral to th e mesencephalon, the basil ar artery are depi cted by low amplitude echoes. 34 2 PIGADAS ET AL. AJNR:2. July / August 1981 A B c Fig. 5. -Horizontal plane at level of lateral ventricles. A, In vitro. B, Anatomic secti on. C, In vivo. Lateral wall of lateral ventric les (paramedian echoes); fa lx cerebri (m idli ne echo). Level of the Cerebral Peduncles Level of Lateral Ventricles Th e anechoic V-shaped mesencephalon is in the center The midline, echogenic, interhemispheric fi ssure is seen of th e im age, with th e constantly seen single strong echo of accommodating the fal x cerebri (fig. 5). Parallel , paramedial, the aqueduct of Sylvius in the center of the tectum (fig. 3). linear echogenic structures are also seen which represent Posteriorl y, th e echogenic tentori al hi atus outlines the su­ th e lateral walls of the lateral ventric les. The inner tabl e of peri or vermis, which is separated from th e mesencephalon the parietal bone is sharpl y defined. Soft echoes interposed by th e quadrigeminal cistern . The lateral margins of the between th e falx cerebri and lateral wall of the lateral ven­ mesencephalon are outlined by th e ambient c istern s, whic h tricle represent combination echoes of the medial wall of th e are situated medial to th e parahippocampal gyri. The am­ lateral ventricle and of the parietal cortex. bi ent cistern s appear to join the c horoid pl exuses of the temporal horn s by their continuation with th e transverse Coronal Plane cerebral fi ssures.