Endocrine Abstracts

Introduction: Somatotroph Pituitary Neuroendocrine Tumor’s (sPitNET) signal intensity in T2-weighted MR images (SI) was reported as prognostic marker for tumor’s aggressiveness and poor response to 1^st generation somatostatin analogs (SSA). Tumors are arbitrary divided into 3 groups: hyperintensive (HYPER), isointensive (ISO) and hypointensive (HYPO).

Aim: Our aim was to quantitatively assess SI of sPitNETs and investigate its clinical implications.

Patients and methods: 116 consecutive patients newly diagnosed with acromegaly between 01.01.2012 and 31.12.2022 at the Department of Endocrinology, Jagiellonian University Medical College were evaluated. Patients with available coronal T2-weighted pituitary MRI images were included. Exclusion criterion was tumor’s cystic component preventing from SI assessment. Finally, 67 patients were in the analysis. SI of the solid part of sPitNETs, grey and white matter of the temporal lobe were measured. Patients were divided into 3 groups: HYPER, with SI higher than grey matter, ISO with SI higher than white matter, but lower than grey matter and HYPO with SI lower than white matter. Baseline and nadir GH after glucose load; IGF-1 and upper limit of normal range for age, sex ratio (IGF%ULN) before and after SSA treatment, tumor volume measured by manual delineation of Volume of Interest (TV), and baseline GH concentration to TV ratio (GH/TV) were compared. This study was approved by the Bioethics Committee (1072.6120.72.2020) and is part of statutory research (N41/DBS/000407).

Results: Median TV was 1.38 cm3 (IQR 4.51) for HYPER, 1.83 cm3 (IQR 6.44) for ISO and (0.58 cm3 IQR 0.73) for HYPO (P=0.005). TV was higher in HYPER than in HYPO (P=0.04) and in ISO than in HYPO (P=0.04), with no differences between HYPER and ISO(P=1.0). Differences in baseline GH, nadir GH in OGTT and IGF1%ULN before and after treatment with SSA, were not significant. GH/TV ratio was higher in HYPO (43.64 uIU/ml*cm³ IQR 48.35) than in HYPER (11.78 uIU/ml*cm³ IQR 15.75) (P= 0.037) and higher in HYPO than in ISO (20.38 uIU/ml*cm³; IQR 32.57)(P=0.005), with no significant differences between HYPER and ISO (P=1.0)

Conclusions: Both HYPER and ISO were larger than HYPO. HYPO may seem more biochemically active than HYPER and ISO tumors. In our cohort, no statistical differences were found between HYPER and ISO tumors. Whether HYPER and ISO tumors constitute two separate groups in terms of clinical significance, requires further research.