Assessment of anatomic morphology of the connective structures among brain ventricles and cerebrospinal fluid movement in them by cerebrospinal fluid spin-labeling MRI

Abstract

Objective To assess the anatomic morphology of the connective structures among brain ventricles and cerebrospinal fluid (CSF) movement in them by CSF spin-labeling MR imaging. Methods According to the order of registration, 50 healthy volunteers were randomly selected and received cerebrospinal fluid spin-labeling MR scan with time-spatial labeling inversion recovery single-shot fast spin echo sequence (SLIR-SSFSE). The tagged CSF was used as an endogenous tracer. The anatomic morphology of the connective structures of brain ventricles and the flow direction of CSF were observed. The longitudinal diameter and transverse diameter of bilateral foramina of monro, midbrain aqueduct, and the central and bilateral lateral apertures of the fourth ventricle of each subject were measured and calculated based on multiple measurements. The flow rate of CSF was calculated based on the flow distance of CSF in the connective structures between brain ventricles during different TI time. The mean value of each indicator was acquired. Results Two-way flow state of CSF was observed in all connective structures, including bilateral foramina of monro, midbrain aqueduct, and the central and bilateral lateral apertures of the fourth ventricle. On the coronal planes, foramen of monro appears as a Y-type tubular structure locating among the both sides of the anteriomedial thalamus and fornix, which connect upward with bilateral lateral ventricles and downward with the third ventricle. The longitudinal diameter and transverse diameter of the left side of foramen of monro were 3.50-5.50 mm[mean (4.37 ±0.47)mm]and 1.00-1.40 mm[mean(1.21 ±0. 13) mm], respectively. The longitudinal diameter and transverse diameter of the right side of foramen of monro were 4. 20-4. 80 mm[mean(4.42 ± 0.20) mm]and 1.00-1.60 mm[mean (1.21 ±0. 19) mm], respectively. On the sagittal planes, foramen of monro appeared as an oblique fine tubular structure with the angle of 55°-58° between the both sides. CSF flow velocity towards the foot was 1.61-2. 52 mm/s[mean (2. 00 ± 0. 17) mm/s]in the left side of foramen of monro and 1.93-2. 20 mm/s [mean (2.03 ±0.09) mm/s]in the right side of foramen of monro. On the sagittal planes, midbrain aqueduct appeared as a curved tubular structure through diencephalon, with the longitudinal diameter of 9.90-17.30 mm[mean(15.51 ± 1.70) mm]and the transverse diameter of 1.70-2.30 mm[mean (1.92 ± 0. 17)mm]. In midbrain aqueduct, CSF flow velocity towards the foot was about 5.00-8.74 mm/s[mean (7.84 ±0.86) mm/s]and towards the head was about 3.84-6.71 mm/s[mean (6. 01 ±0. 66) mm/s]. On the sagittal plane, the central apertures of the fourth ventricle appeared as a fork-like tubular structure, with a small bifurcation forward to the central canal of the medulla oblongata and a posterior branch downward to cerebellomedullary cistern. On the coronal plane, lateral apertures of the fourth ventricle appeaed as curved tubular structures connecting the lateral horn of the fourth ventricle and cerebellomedullary cistern. The longitudinal diameter and transverse diameter of the left lateral aperture were 6.30-14. 60 mm[mean (10.42 ±2.88) mm]and 1.00-1.50 mm[mean (1.24 ±0.18) mm],respectively; of the right lateral aperture, they were 6. 20-15.50 mm[mean (12. 13 ± 3.05) mm]and 1.00-1.40 mm[mean(1.19 ±0. 13) mm], respectively. The angle range between the left and right lateral aperture was from 87° to 114°. CSF flow velocity towards the foot was about 2. 89-6. 70 mm/s[mean (4. 78 ± 1.32) mm/s]in the left lateral aperture and 2. 84-7.11 mm/s[mean (5.56 ±1.40) mm/s]in the right lateral aperture. Conclusions CSF spin-labeling MR imaging could display the anatomic morphology of the connective structure among brain ventricles and could be used for noninvasively assessing CSF movement. Key words: Cerebrospinal fluid; Cerebral ventricles; Magnetic resonance imaging; Dissection