Endocrine Abstracts

Objectives: i) To measure olfactory bulbs and sulci using dedicated magnetic resonance imaging (MRI) sequences in idiopathic isolated hypogonadotropic hypogonadism (IHH) patients with a well detailed phenotype characterization. ii) To correlate MRI findings with a clinical smell test.

Methods: SUB:Pituitary – Clinical (Generously supported by IPSEN)MRI was performed in 20 patients (all males, aged between 11 and 45 years, mean age of 26) with IHH and olfactory dysfunction was assessed using the smell identification test (UPSIT), a qualitative suprathreshold olfaction test obtained from the Universityof Pennsylvania. Coronal spin echo T2-weighted and volumetric T1-weighted gradient echo sequences were acquired in a 1.5T system. ImageJ software was used to obtain olfactory bulb volumes and olfactory sulcus depths and lengths. Data were analyzed with SPSS 15.0 and the Kappa index was used to evaluate the agreement between the UPSIT and MRI.

Results: The UPSIT revealed normosmia, hyposmia and anosmia in 10 (50%), 4 (20%) and 6 (30%) patients respectively. Fourteen patients (70%) had olfactory abnormalities in the MRI. Commonest abnormality was hypoplasia seen in 8 patients (40%). Five patients (25%) had olfactory bulb. One patient had unilateral hypoplasia with normal sense of smell. There was moderate agreement between the MRI quantitative evaluation and the UPSIT (overall Kappa =0.55).

Discussion: Olfactory bulb and sulcus aplasia were the most common findings in IHH patients (70%). We objectively demonstrated agreement between MRI findings and the smell test, especially the presence of bulb aplasia and anosmia, confirming the high specificity of MRI findings.

Conclusion: Therefore, our findings help ascertain MRI accuracy in the diagnosis of IHH, differentiating patients with hypogonadotropic hypogonadism with an apparently normal or difficult to evaluate sense of smell.