RPS 312 - New insights in paediatric head and neck imaging

Purpose:

To retrospectively evaluate neurodevelopmental outcomes (NDO) of prenatally diagnosed isolated posterior fossa abnormalities characterised on foetal MRI.

Methods and materials:

Out of 821 foetal MRIs performed on pregnant women referred to a tertiary referral centre from May 2015-July 2018, 66 were done for the further evaluation of isolated posterior fossa abnormalities suspected in ultrasound. Post-delivery follow-up was done by a trained examiner using national registry data and parental phone calls. The abnormal outcome was defined as an ASQ score below the cut-off for age and related skill. Pregnancy termination due to a foetal anomaly or foetal death (TOPFA/FD) was recorded.

Results:

The maternal age was 29.3±5.7. Gestational ages at the time of the MRI were 24.7±5.9. Out of 66 cases, 19 cases were diagnosed as normal, 3 were lost to follow-up (LTFU), 1 foetal death, 13 normal, and 2 abnormal NDO (minor communication, fine motor, and problem-solving issues). Out of 36 foetuses referred for possible vermian hypoplasia, 15 foetuses were diagnosed with inferior vermian hypoplasia (4 TOPFA/FD, 6 LTFU, 3 normal, and 2 abnormal NDO), 14 were diagnosed as possible BPC before 19 wks GA (2 LTFU, 2 TOPFA/FD, 8 normal, and 2 abnormal NDO (mean ASQ 217, minor communication issues)), and 5 were diagnosed as mega cisterna magna (1 LTFU and 4 normal NDO). The worse outcome was with cerebellar hypoplasia (5 TOPFA/FD and 1 LTFU) and dandy-walker malformation (6 TOPFA/FD and one abnormal NDO).

Conclusion:

MRI is fairly accurate in ruling out clinically significant posterior fossa abnormality even before 19 weeks GA. Prenatally diagnosed cerebellar hypoplasia and DWM are uniformly associated with a poor prognosis. Most cases of BPC have a normal and most cases of IVH have an abnormal NDO.

Limitations:

n/a

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

To establish normal values of foetal optic structures as a reference for future in vivo imaging studies.

Methods and materials:

Postmortem foetal MRI data of 33 foetuses with normal development of optical structures and 25 foetuses with pathologies (GW 16-42) were analysed. The pathology group included complex malformations (15), intrauterine growth restriction (2), premature rupture of membranes (4), twin-associated problems (3), and stillbirth (1). MRI was performed on a 3 Tesla scanner utilising an 8-channel knee coil. Retrobulbar and intracranial optic nerve diameters, optic nerve length, the angle between optic nerves, and minimum transverse diameter of the optic chiasm were obtained. Correlations with gestational age were performed. Measurements were performed using free Image J software on T2-weighted images (TR 300ms, TE 140 ms, and isovoxel 0.4mm ciss 3d sequence).

Results:

The optic nerve length increased from 10.5-29.41 mm within 26 GW. The retrobulbar optic nerve diameter increased from 0.83 (right)/0.860 (left) mm to 2.13 (right)/ 2.10 (left) mm. The transverse diameter of the optic chiasm increased from 4.1-6.7 mm within 24 weeks. The angle between the optic nerves decreased by 36.5 degrees within 26 weeks. Optic structure measurements correlated significantly with gestational age. Foetuses in the pathology group had at least one aberration from the normal values.

Conclusion:

Postmortem foetal MRI-based optic structure measurements correlated with gestational age and showed a change in orientation of the optic chiasm from a U shape at early gestation towards a V shape at later gestation. Based on the presented normal values, developmental defects can be detected sensitively.

Limitations:

More studies are needed to investigate translation to in vivo foetal MRI.

Ethics committee approval

This study was approved by the institutional review board.

Funding:

No funding was received for this work.

Purpose:

To describe the findings of brain MRI in children affected by Congenital Zika Virus Syndrome (CZS) with and without sensorineural hearing loss (SHL).

Methods and materials:

A retrospective cross-sectional study with two groups with confirmed CZS: group A consisted of 9 children with SHL and group B consisted of 27 without SHL. They had a hearing evaluation through BERA and had brain and/or inner ear MRI. The images were qualitatively evaluated by a radiologist and two otolaryngologists.

Results:

Of the 4 patients with SHL who had MRI of the inner ear, we identified two of them with hypoplasia of the cochlear nerve ipsilateral to profound hearing loss. The brainstem hypoplasia was identified to some degree in all patients evaluated, with 66% of those of group A and 55.6% of the group B being classified as severe or very severe without statistical significance. In the evaluation of the temporal parenchyma, in group A we found 8 (88,9%) and in group B 16 (59,3%) classified as severe or very severe hypoplasia also without statistical significance.

Conclusion:

Hypoplasia of the cochlear nerve was identified as related to profound hearing loss. There was no association between peripheral SHL identified by BERA and brainstem or temporal parenchyma hypoplasia. These findings suggest that SHL in CZS is related to sensory damage to the cochlear nerve. Studies of brain changes with more complex hearing skills should be evaluated in later studies.

Limitations:

The small sample of children with CZS with sensorineural hearing loss.
We studied children with a more severe spectrum of the syndrome.

Ethics committee approval

Ethics committee approval obtained.

Funding:

No funding was received for this work.

Purpose:

Although the focus in patients after laryngotracheal stenosis (LTS) is mainly on airway function, dysphonia is a common sequela that strongly influences the quality of life of patients. Dysphonia is caused by pre-existing stenosis and anatomical distortion due to airway reconstruction. Magnetic resonance imaging (MRI) is ideal to assess the vocal cords in static and dynamic conditions. The aim of this study was to image the vocal cords in children post airway reconstruction for LTS on static and dynamic MRI and to compare these findings to voice outcome.

Methods and materials:

Patients filled out a voice-related questionnaire ((paediatric) voice handicap index (p)VHI), the quality of the voice was tested with the dysphonia severity index (DSI), and static and dynamic upper airway MRI during free-breathing, inspiration and phonation (3T GE scanner, 6CH carotid coil, spatial resolution 0.5x0.5 (in plane) x2 mm, temporal resolution: 240 ms) was performed. Post-surgical anatomy, areas, diameters, and movement of the vocal cords were analysed.

Results:

48 patients (age 14.4 (11.7-19.4) years) and 11 healthy volunteers (age 15.9 (8.4-20) years) were included. Patients showed a high score on the (p)VHI (26.2±18.6%) and a decrease in DSI score (-2.6±2.4 vs 0.68±2.9, p<0.001) compared to healthy volunteers, representing dysphonia. MRI showed vocal cord (80.9%) and arytenoid thickening (59.6%). Furthermore, impaired adduction during phonation (61.7%) was seen, highly correlated to both (p)VHI and DSI score (odds 1.05 (1.01-1.09), p=0.02 and 0.65 (0.48-0.88), p=0.006).

Conclusion:

Static and dynamic MRI is an excellent, non-invasive method to visualise the causes of dysphonia in combination with anatomy in paediatric patients with a history of LTS.

Limitations:

n/a

Ethics committee approval

Approval by the local medical ethics committee (MEC-2018-013) and written informed consent was obtained.

Funding:

Funded by the Vrienden van het Sophia Foundation.

Purpose:

To compare images from an experimental 1T permanent MRI scanner in the NICU to clinical 1.5T images.

Methods and materials:

This was a prospective, non-randomised, feasibility study. Stable premature infants born prior to 28th week, or born between the 28th-32nd week of pregnancy with IVH, US abnormalities, severe morbidity, or abnormal neurological exam, underwent scanning at near term equivalent age with both conventional 1.5T and dedicated neonatal 1T MRI. MRI scans included T1, T2, and diffusion-weighted imaging performed on a conventional 1.5T (Aera, Siemens) and on a novel 1T MRI (Embrace, Aspect) located in the NICU. No more than 72 hours elapsed between the two studies. 3 radiologists blindly reviewed the images for the following: 10 predetermined anatomical structures, bilateral measurement of ADC values in the supraventricular white matter and vitreous humour, and notation of pathological findings. Findings and comparisons were subject to statistical analysis.

Results:

55 neonates were included in the study. 17 were scanned only on the 1T NICU scanner due to lack of parental consent for a second scan. Identification of the anatomical structures was similar for all 10 locations (P=0.64). Normalised ADC values of the white matter were similar (P=0.31, 0.44 for left and right, respectively). Bland Altman analysis demonstrated excellent agreement. 131 pathological findings were noted involving the parenchyma and ventricles on both scanners. Conspicuity of haemorrhage was slightly better on the 1.5T scanner (P<0.01).

Conclusion:

The 1T neonatal scanner performs as well as a clinical scanner and is a potential clinical tool for use in the NICU.

Limitations:

At the time of the study, SWI imaging was not available on the 1T scanner.

Ethics committee approval

Approved by IRB. Parental consent required.

Funding:

Aspect Imaging.

Purpose:

To describe the brain elasticity of very preterm infants during development compared to term-born controls and to determine the diagnostic role of cerebral quantitative shear-wave elastography (SWE) in preterm children compared to standard cranial ultrasound (US) examination.

Methods and materials:

34 very preterm from 24 to 27+6 gestational weeks (GW) and 47 preterms (28 to 31+6 GW) underwent sequential brain US with elasticity measurement from birth to term.

18 term-born controls had the same protocol at birth.

On conventional US, frontal and parietal white matter (WM) was classified as normal or abnormal according to its echogenicity compared to plexus. Quantitative measurements of brain stiffness were performed with SWE in bilateral frontal and parietal WM and thalami.

Descriptive statistical analysis and multivariate analysis (ANOVA) for comparison between groups were performed.

Results:

A progressive increase of brain stiffness was demonstrated with increased gestational age in all brain areas.

Brain stiffness was higher in parietal than in frontal WM at any gestational age.

WM elasticity values measured at term remained significantly lower in both subgroups of preterms compared to controls (p=0.04 and p=0.003 in frontal WM; p=0.003 and p=0.09 in parietal WM).

Brain WM elasticity was similar between preterm infants with or without abnormal WM on standard US examination.

Conclusion:

Brain stiffness values change according to the gestational age with an anteroposterior gradient that might reflect normal brain maturation.

WM stiffness of very preterm infants remains lower than control newborns even at term.

Brain stiffness values do not seem to reflect the WM alterations found on conventional US but should be compared to MRI as the gold standard method.

Limitations:

The lack of interobserver correlation and the decreasing number of preterms throughout the study.

Ethics committee approval

Ethics committee approval obtained.

Funding:

No funding was received for this work.

Purpose:

A quantitative anatomical 3D sequence was optimised for paediatric application and used to build quantitative brain maturation atlases, mapping both the volumetric and T1-relaxometry changes. This allows for a comprehensive assessment of anatomy, morphometry, and a marker for brain microstructure (T1 relaxometry).

Methods and materials:

We performed a two-year single-centre prospective study recruiting infants aged 1-16 years from a university hospital to be scanned at 1.5T (MAGNETOM Aera, Siemens Healthcare, Erlangen, Germany) using a 20-channel head coil without sedation. A single prototype MP2RAGE scan (TI1/TI2=600/2,000 ms, TR=5,000 ms, voxel size=1.33x1.33x1.25 mm³ isotropic, TA=6:42 min) was performed. The supposed medical condition was an isolated headache with spontaneously favourable evolution. Brain maturation was modelled based on resulting T1 maps and volumetry (using the MorphoBox prototype adapted for paediatrics).

Results:

63 normal brain MRIs (33 female) were obtained. Automated segmentation and T1-mapping was successful in all scans. The evolution of volumes and T1 values were modelled over age to obtain reference ranges (without gender difference). The absolute volume of white matter increased continuously during childhood, with stable cortical grey matter volumes. Reference regional T1 values decreased rapidly during the first two years of age (supposedly showing myelinisation) and then more smoothly.

Conclusion:

In addition to anatomical T1 images, the 3D MP2RAGE sequence allows for automated morphometric and relaxometry assessment. Based on this data, we created reference brain maturation atlases covering the entire childhood which have the potential to quantitatively support clinical decision making in paediatrics.

Limitations:

A single-centre study with a limited sample of patients.

Ethics committee approval

Approved by the local ethics committee for human research (RNI-2017-093).

Funding:

GF Piredda, T Hilbert, B Maréchal, and T Kober are Siemens Healthineers employees.

Purpose:

To evaluate the association and correlation between blood pressure (BP) and posterior reversible encephalopathy syndrome (PRES) imaging severity in the paediatric population in whom radiological features and pathophysiology remains obscure.

Methods and materials:

A retrospective evaluation of paediatric patients diagnosed with PRES over the last 10 years at Aga Khan University was performed. Radiological findings were reviewed by two paediatric radiologists along with the clinical profile and outcome. Imaging severity was categorised into mild, moderate, and severe. The distribution of lesions, enhancement, diffusion restriction, and haemorrhage were assessed. Various conditions that may resemble PRES were excluded.

Results:

Out of 43 children, 20 were males and 23 were females with a mean age of 10.7 years. The most common primary disease was malignancy (28%) out of which lymphoma predominated. The mean systolic BP was 131.5 (70-205) mmHg and diastolic was 82.9 (35-170) mmHg. 14 children had hypertension higher than autoregulatory limits. Imaging showed a parieto-occipital lobe involvement pattern in 42% of cases, holohemisphereic pattern in 30.2%, cerebellar involvement in 23.3%, and superior frontal sulcus pattern in 2.3%. 4.7% had a haemorrhage, 25.6% had contrast enhancement, and 27.9% had a positive diffusion restriction (cytotoxic oedema). No statistically significant association of imaging severity with BP (P=0.70), imaging severity with haemorrhage (P=0.30), and diffusion restriction (P=0.64) with imaging severity and with each other (P=1) was seen.

Conclusion:

We did not find any statistically significant association of blood pressure with imaging severity, haemorrhage, and diffusion restriction (cytotoxic oedema). Further prospective studies are needed to determine the pathophysiological mechanisms and their correlation with imaging findings in PRES in children.

Limitations:

The retrospective study design and single-centre study.

Ethics committee approval

Ethics committee approval obtained.

Funding:

No funding was received for this work.

Purpose:

To evaluate the difference in apparent diffusion coefficient values (ADC) between foetuses with bilateral and unilateral isolated mild ventriculomegaly.

Methods and materials:

In this retrospective study, we included 64 foetuses with mild ventriculomegaly at our institution from January 2015-December 2018, of which 47 foetuses had isolated unilateral mild ventriculomegaly, 17 had bilateral mild ventriculomegaly, and the degree of ventricular dilatation was 10 mm-15 mm. Another 36 normal foetuses were selected as a control group. The ADC values of frontal white matter, temporal white matter, occipital white matter, parietal white matter, basal ganglia, thalamus, cerebellar hemisphere, pons, and cerebrospinal fluid were measured three times in each region, and the average ADC values were calculated. The differences in ADC values among the groups were compared.

Results:

There was no significant difference in the ADC values between the left and right brain regions of the 3 groups (P>0.05). The average ADC values of each brain region were calculated. Compared with the control group, the ADC value of the frontal white matter in foetuses with unilateral mild ventriculomegaly was decreased (p<0.001), the ADC value of the temporal white matter was reduced (p=0.027), and the difference was statistically significant. The ADC values between the bilateral mild ventriculomegaly and control groups were not significantly different.

Conclusion:

There are potential changes in frontal lobes of foetuses with isolated unilateral mild ventriculomegaly and the changes in ADC may be helpful to understand the damage to ventricular microstructures. Bilateral mild ventriculomegaly may have fewer effects on brain microstructures.

Limitations:

A single-centre, retrospective study. The study group on bilateral VM was relatively small.

Ethics committee approval

n/a

Funding:

Science and Technology Commission Shanghai Municipality [No. 19ZR1407200].