Cochlear implantation in a 10-year old boy with Pendred syndrome and extremely enlarged endolymphatic sacs.

A 10-year-old boy with fluctuating sensorineural hearing loss (SNHL) and biallelic mutations in the SLC26A4 gene and with inner ear anomalies received a cochlear implantation. SLC26A4 mutations are associated with variable degrees of SNHL and enlarged vestibular aqueducts (EVA), identified either as non-syndromic EVA or classic Pendred syndrome; the latter also associated with thyroid dysfunction. The inner ear malformations in this group of patients have been considered a relative contraindication against cochlear implantation because of the potential per- and postoperative complications such as peroperative cerebrospinal fluid leak or postoperative vestibular symptoms. In the current case there were no surgical or postoperative complications, indicating that extremely enlarged endolymphatic sacs are not as such a contraindication for cochlear implantation. This case also illustrates the management dilemma of an appropriate timing for cochlear implantation.

Hepatic galactose metabolism quantified in humans using 2-18F-fluoro-2-deoxy-D-galactose PET/CT.

UNLABELLED: Accurate quantification of regional liver function is needed, and PET of specific hepatic metabolic pathways offers a unique method for this purpose. Here, we quantify hepatic galactose elimination in humans using PET and the galactose analog 2-(18)F-fluoro-2-deoxy-d-galactose ((18)F-FDGal) as the PET tracer. METHODS: Eight healthy human subjects underwent (18)F-FDGal PET/CT of the liver with and without a simultaneous infusion of galactose. Hepatic systemic clearance of (18)F-FDGal was determined from linear representation of the PET data. Hepatic galactose removal kinetics were determined using measurements of hepatic blood flow and arterial and liver vein galactose concentrations at increasing galactose infusions. The hepatic removal kinetics of (18)F-FDGal and galactose and the lumped constant (LC) were determined. RESULTS: The mean hepatic systemic clearance of (18)F-FDGal was significantly higher in the absence than in the presence of galactose (0.274 ± 0.001 vs. 0.019 ± 0.001 L blood/min/L liver tissue; P < 0.01), showing competitive substrate inhibition of galactokinase. The LC was 0.13 ± 0.01, and the (18)F-FDGal PET with galactose infusion provided an accurate measure of the local maximum removal rate of galactose (V(max)) in liver tissue compared with the V(max) estimated from arterio-liver venous (A-V) differences (1.41 ± 0.24 vs. 1.76 ± 0.08 mmol/min/L liver tissue; P = 0.60). The first-order hepatic systemic clearance of (18)F-FDGal was enzyme-determined and can thus be used as an indirect estimate of galactokinase capacity without the need for galactose infusion or knowledge of the LC. CONCLUSION: (18)F-FDGal PET/CT provides an accurate in vivo measurement of human galactose metabolism, which enables the quantification of regional hepatic metabolic function.