MRI measurements of the normal pediatric optic nerve pathway.

The purpose of this work is to establish a reference scale of optic nerve pathway measurements in pediatric patients according to age using MRI. Optic nerve pathway measurements were retrospectively analyzed using an orbits equivalent sequence on brain MRI scans of 137 pediatric patients (72 male, 65 female, average age = 7.7 years, standard deviation  = 5.3). The examinations were performed on a 1.5-T or 3-T Siemens MR system using routine imaging protocols. Measurements include diameters of the orbital optic nerves (OON), prechiasmatic optic nerves (PON), optic tracts (OT), and optic chiasm (OC). Measurements were performed manually by 2 neuroradiologists, using post-processing software. Patients were stratified into five age groups for measurement analyses: (I) 0-1.49 years, (II) 1.5-2.99 years, (III) 3-5.99 years, (IV) 6-11.99 years, and (V) 12-18 years. The observed value range of OON mean diameter was 2.7 mm (Interquartile range (IQR) = 2.4-2.9), PON was 3.2 mm (IQR  =  3.05-3.5), OT 2.6 mm (IQR = 2-2.9). A strong positive correlation was established between age and mean diameter of OON (r = 0.73, p < .001), PON (r = 0.59, p < .001), and OT (r = 0.72, p < .001). A significant difference in mean OON diameters was found between age groups I-II (d = 0.3, p = .01), II-III (d = 0.5, p < .001), III-IV (d = 0.5, p < .001) followed by a plateau between IV-V (d = 0.l0, p = .19). OON/OT ratio maintained a steady mean value 1 (IQR = 0.93-1.1) regardless of age (p = .7). The diameter of optic pathways was found to increase as a function of age with consistent positive correlation between nerve and tract for all ages.

The quantitative evaluation of intracranial pressure by optic nerve sheath diameter/eye diameter CT measurement.

BACKGROUND: The changes of the optic nerve sheath diameter (ONSD) have been used to assess changes of the intracranial pressure for 20 years. The aim of this research was to further quantify the technique of measuring the ONSD for this purpose. METHODS: Retrospective study of computed tomographic (CT) data of 1766 adult patients with intracranial hypotension (n=134) or hypertension (n=1632) were analyzed. The eyeball transverse diameter (ETD) and ONSD were obtained bilaterally, and the ONSD/ETD ratio was calculated. The ratio was used to calculate the normal ONSD for patients and to estimate the intracranial pressure of the patients before and after the onset of the pathology. Correlation analysis was performed with invasively measured intracranial pressure, the presence or absence of papilledema, sex, and age. RESULTS: In hypotension cases, the ONSD by CT was 3.4±0.7 mm (P=.03 against normative 4.4±0.8 mm). In cases with hypertension, the diameter was 6.9±1.3 (P=.02, with a cutoff value ˃5.5 mm). The ONSD/ETD ratio was 0.29±0.04 against 0.19±0.02 in healthy adults (P=.01). CONCLUSION: The ONSD and the ONSD/ETD ratio can indicate low intracranial pressure, but quantification is impossible at intracranial pressure less than 13 mm Hg. In elevated intracranial pressure, the ONSD and the ratio provide readings that correspond to readings in millimeters of mercury. The ONSD method, reinforced with additional calculations, may help to indicate a raised intracranial pressure, evaluate its severity quantitatively, and establish quantitative goals for treatment of intracranial hypertension, but the limitations of the method are to be taken into account.

Should Intravenous Contrast be Administered in MRI Evaluation of Pediatric Outpatients with Chronic Headache?

BACKGROUND: The practice of administering intravenous contrast to children varies by institution depending on their routine. OBJECTIVES: To assess the necessity of routine contrast administration in brain magnetic resonance imaging (MRI) of pediatric outpatients referred for chronic headache workups. METHODS: We conducted a retrospective review of consecutive pediatric brain MRI examinations performed during January and February 2014 in 30 pediatric outpatients referred for evaluation of chronic headache. Independent review was performed by two board-certified neuroradiologists. The raters reviewed each MRI first as a non-contrast examination (without seeing the post-contrast images) and then with post-contrast images. RESULTS: No abnormalities were found in six patients. One patient had an indeterminate finding of a tubular cerebellar lesion requiring follow-up. In the remaining patients (n = 23), the findings were subclinical and included: mucosal thickening in the paranasal sinuses in 9 patients, cystic changes of the pineal gland in 8 (size 2-9 mm), small developmental venous anomalies in 6, non-specific FLAIR hyperintensities in 4, opacification of the mastoids in 2, and telangiectasia in 1 patient. The subclinical cases that were missed on pre-contrast images were: one small developmental venous anomaly, one telangiectasia and one small pineal cyst, none of which hold clinical significance. All kappa inter-rater and intra-rater agreement scores resulted in values above 0.75, excellent agreement according to Fleiss guidelines. CONCLUSIONS: There seems to be little reason to medically justify large-scale use of routine IV contrast administration to evaluate a brain MRI of pediatric patients referred for chronic headache.

Familial wandering spleen: a first instance.

We report on 2 sisters presenting with acute torsion of a wandering spleen within a 3-year interval. The diagnosis was made preoperatively by computed tomography (CT) in both cases. A high index of suspicion because of our experience with the first patient, who underwent splenectomy, enabled a correct early diagnosis in the sibling. On urgent surgery, reversible ischemic changes were found, and detorsion and splenopexy resulted in preservation of the spleen.