Solitary necrotic nodule of the liver: a single-centre retrospective CEUS study of 87 lesions

To retrospectively characterise the sonographic features of solitary necrotic nodules of the liver (SNNL) on conventional ultrasound (US) and contrast‑enhanced ultrasound (CEUS), and to identify imaging features supporting differential diagnosis. Eighty‑one consecutive patients with SNNL (32 males, 49 females; mean age 51.2 ± 12.0 years) were included from December 2014 to March 2018. Diagnosis was confirmed by histopathology ( n = 8), contrast‑enhanced CT/MRI with follow‑up ( n = 13), or US follow‑up ( n = 60). Two blinded radiologists independently evaluated all US and CEUS features, and discrepant results were resolved by a senior radiologist through consensus discussions. Group comparisons used chi‑square/Fisher’s exact, t‑test/Mann-Whitney U, and the phi correlation coefficient (φ) for correlation analysis. Eighty‑seven lesions were analysed (median diameter 26 mm; range 7–60). Most were irregular (77.0%, 67/87), including 55 with a tortuous cord‑like configuration. Central hyperechoic foci (“equal‑sign-like” or core‑type) occurred in 18.4% (16/87). Two CEUS patterns were identified: absence of enhancement throughout all phases (55.2%, 48/87) and peripheral arterial rim hyperenhancement with persistent central nonenhancement (44.8%, 39/87). The median thickness of the arterial enhancement rim was 3.1 mm (Interquartile Range, IQR 2.5–5.1), and thick rims (≥ 5 mm) were detecteded in 11/39 (28.2%). Round‑like lesions more often showed central microcystic structures (25.0% vs. 0%; p < 0.001; φ = 0.452) and central hyperechoic foci (60.0% vs. 6.0%; p < 0.0001; φ = 0.587) compared with irregular lesions. Portal‑phase washout was more frequent in thick‑rim lesions (45.5% vs. 3.6%; p = 0.01; φ = 0.522). Post‑contrast lesion enlargement on CEUS occurred more often in thick‑rim than thin‑rim lesions (72.7% vs. 28.6%; p = 0.027; φ = 0.404). SNNL exhibits characteristic US and CEUS imaging features. Tortuous cord‑like morphology and central “equal‑sign-like” echogenic foci may support diagnosis. A thick arterial rim (≥ 5 mm) correlated with prominent portal-phase washout and appreciable lesion size increase on CEUS, which may offer a novel exploratory perspective for the imaging characterization of solitary necrotic nodules and deserves clinical attention.