Neuroendocrine Carcinoma of the Urinary Bladder: CT Findings and Radiomics Signature.

Background : We present a case series of Neuroendocrine Carcinoma of the Urinary Bladder (NECB) to analyse their radiologic appearance on CT, find a "Radiomic signature", and review the current literature. Methods : 14 CT cases of NECB were reviewed and compared with a control group of 42 patients with high-grade non-neuroendocrine bladder neoplasm for the following parameters: ring enhancement; implantation site; dimensions; density; margins; central necrosis; calcifications; number of lesions; wall thickness; depth of invasion in the soft tissue; invasion of fat tissue; invasion of adjacent organs; lymph-node involvement; abdominal organ metastasis. To extract radiomic features, volumes of interest of bladder lesions were manually delineated on the portal-venous phase. The radiomic features of the two groups were identified and compared. Results : Statistical differences among NECB and control group were found in the prevalence of male sex (100% vs. 69.0%), hydronephrosis (71.4% vs. 33.3%), mean density of the mass (51.01 ± 15.48 vs. 76.27 ± 22.26 HU); product of the maximum diameters on the axial plane (38.1 ± 59.3 vs. 14.44 ± 12.98 cm2) in the control group, trigonal region involvement (78.57% vs. 19.05%). About the radiomic features, Student's t -test showed significant correlation for the variables: "DependenceNonUniformity" ( p : 0.048), "JointAverage" ( p : 0.013), "LargeAreaLowGrayLevelEmphasis" ( p : 0.014), "Maximum2DDiameterColumn" ( p : 0.04), "Maximum 2DDiameterSlice" ( p : 0.007), "MeanAbsoluteDeviation" ( p : 0.021), "BoundingBoxA" ( p : 0.022) and "CenterOfMassB" ( p : 0.007). Conclusions : There is a typical pattern (male patient, large mass, trigonal area involvement) of NECB presentation on contrast-enhanced CT. Certain morphological characteristics and encouraging results about Radiomic features can help define the diagnosis.