Objective: To identify specific quantitative contrast-enhanced ultrasound (CEUS) parameters that could distinguish kidney transplants with significant histopathological injury.Methods: Sixty-four patients were enrolled in this prospective observational study.Biopsies were performed following CEUS and blood examination.Results: 28 biopsy specimens had minimal changes (MC group), while 36 had significant injury (SI group). Of these, 12 had rejection (RI group) and 24 non-rejection injury (NRI group). In RI and NRI groups, temporal difference in time to peak (TTP) between medulla and cortex (ΔTTPm-c) was significantly shorter compared to the MC group (5.77, 5.92, and 7.94 s, P = 0.048 and 0.026, respectively). Additionally, RI group had significantly shorter medullary TTP compared to the MC group (27.75 vs. 32.26 s; P = 0.03). In a subset of 41 patients with protocol biopsy at 1-year post-transplant, ΔTTPm-c was significantly shorter in the SI compared to the MC group (5.67 vs. 7.67 s; P = 0.024). Area under receiver operating characteristic curves (AUROCs) for ΔTTPm-c was 0.69 in all patients and 0.71 in patients with protocol biopsy.Conclusions: RI and NRI groups had shorter ΔTTPm-c compared to the MC group.AUROCs for both patient groups were good, making ΔTTPm-c a promising CEUS parameter for distinguishing patients with significant histopathological injury.

The purpose of this review is to become familiar with the terminology and typical presentation of vascular anomalies in children and to present the imaging approach to these anomalies. Vascular anomalies are the most common cause of soft-tissue masses in children. Many physicians are not familiar with the correct terminology for vascular anomalies which results in errors in diagnosis, prognosis, and treatment. The updated International Society for the Study of Vascular Anomalies classification, based on the original Hamburg classification, divides vascular anomalies into two types: vascular tumours (haemangiomas) and vascular malformations (venous, lymphatic, arteriovenous). Grey-scale and Doppler ultrasound (US) are the initial imaging modalities in suspected vascular anomalies. Grey-scale US is highly nonspecific. Therefore, a diagnostic algorithm based on grey-scale and Doppler signs is proposed. Spectral Doppler analysis reveals the type of vascular flow present within the lesion: high-flow is typical for infantile haemangiomas and arteriovenous malformations, low-flow for venous and noflow for lymphatic malformations. Magnetic resonance imaging with angiography is indicated only when US has not been diagnostic, when the lesion is too big or lies too deeply, and when information about the accurate anatomic location and possible infiltration of surrounding structures is necessary. Digital subtraction angiography is performed when interventional treatment is considered. Conclusion − The new terminology of vascular anomalies should be used in everyday clinical practice to avoid misunderstandings. Grey-scale and Doppler US are the most important imaging modalities for the accurate diagnosis and follow-up of vascular anomalies in children.