Brain stem/brain stem occipital bone ratio and the four-line view in nuchal translucency images of fetuses with open spina bifida

Abstract

Objective: Brain stem depth/brain stem occipital bone distance (BS/BSOB ratio) and the four-line view, in images obtained for nuchal translucency (NT) screening in fetuses with open spina bifida (OSB). Methods: Single center, retrospective study based on the assessment of NT screening images of fetuses with OSB. A ratio between the BS depth and the BSOB distance was calculated (BS/BSOB ratio) and the four-line view observed, and the sensitivity for a BS/BSOB ratio superior/equal to 1, and for the lack of detection of the four-line view were calculated. Results: There were 17 cases of prenatal diagnosis OSB. In six cases, the suspicion on OSB was raised during NT screening, in six cases, the diagnosis was made before 20 weeks and in five cases during anomaly scan. The BS/BSOB ratio was superior/equal to 1 in all 17 cases, and three lines, were visualized in 15/17 images of the OSB cases, being the sensitivity 100% (95% CI, 81 to 100%) and 88% (95% CI, 65 to 96%). Conclusion: Assessment of BS/BSOB ratio and four-line view in NT images is feasible detecting affected by OSB with high sensitivity. The presence of associated anomalies or of an enlarged NT enhances the early detection.

Intracranial translucency assessment at first trimester nuchal translucency ultrasound

“…In addition to the absence, 7,8,15,20 or reduced thickness of the IT, 13,14 other potential markers include obliteration of the cisterna magna, 9,10 increased anteroposterior diameter of the brain stem (BS), decreased brain stem to occipital bone diameter (BSOB) and an increased BS to BSOB ratio (BS/BSOB), 11,12,17,18 reduced posterior fossa fluid area 16 and simply an abnormal four-line view. 10,12,18 Other findings linked to early diagnosis of OSB at the nuchal scan, using views other than the mid sagittal view of the face, include small BPD, 21 small BPD to transverse abdominal diameter ratio 22 and reduced cerebral ventricular volume. 23 Initially in 2009, Chaoui et al 7 reported a sensitivity and specificity of 100% for absence of IT for detection of OSB.…”

“…5 Over recent years, an abnormal posterior fossa on the mid-sagittal view of the face at the first trimester nuchal translucency scan, performed at 11-13+6 weeks' gestation, has been associated with the presence of OSB. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] The mid-sagittal view of the face has been routinely obtained in order to measure nuchal translucency (NT) thickness and assess the nasal bones as part of screening for chromosomal abnormalities.…”

Reference Ranges for Transvaginal Examined Fossa Posterior Structures in Fetuses from 45 to 84 mm Crown-Rump Length

“…This observation underlines the feasibility for diagnosing pathological conditions by direct visualization of the affected structure. Using a combined approach of BS-BSOB ratio [13] and single-line sign [14, 15] in addition to our created reference values could improve the detection rate and differential diagnosis of cystic posterior fossa abnormalities such as Dandy Walker malformation, vermian hypoplasia, and BP cyst [13, 16, 17]. …”

Sonographic detection of central nervous system defects in the first trimester of pregnancy

“…To solve this issue, other posterior brain markers have been proposed . These include measurements of the cisterna magna , the brain stem and the brain stem occipital bone distance (BSOB), the posterior fossa fluid area, and the four‐line view (Figure ) . The anterior–posterior diameter of the cisterna magna can be measured in a mid‐sagittal view .…”

“…66 These include measurements of the cisterna magna, the brain stem and the brain stem occipital bone distance (BSOB), the posterior fossa fluid area, and the four-line view (Figure 3). 67,68 The anterior-posterior diameter of the cisterna magna can be measured in a midsagittal view. 69 Non-visualization of the cisterna magna, or a cisterna magna width below the fifth percentile, achieves sensitivity for OSB of 50% to 73%.…”