Role for contrast-enhanced ultrasound in assessing complications after kidney transplant

Abstract

Kidney transplantation (KT) is an effective treatment for end-stage renal disease. Despite their rate has reduced over time, post-transplant complications still represent a major clinical problem because of the associated risk of graft failure and loss. Thus, post-KT complications should be diagnosed and treated promptly. Imaging plays a pivotal role in this setting. Grayscale ultrasound (US) with color Doppler analysis is the first-line imaging modality for assessing complications, although many findings lack specificity. When performed by experienced operators, contrast-enhanced US (CEUS) has been advocated as a safe and fast tool to improve the accuracy of US. Also, when performing CEUS there is potentially no need for further imaging, such as contrast-enhanced computed tomography or magnetic resonance imaging, which are often contraindicated in recipients with impaired renal function. This technique is also portable to patients’ bedside, thus having the potential of maximizing the cost-effectiveness of the whole diagnostic process. Finally, the use of blood-pool contrast agents allows translating information on graft microvasculature into time-intensity curves, and in turn quantitative perfusion indexes. Quantitative analysis is under evaluation as a tool to diagnose rejection or other causes of graft dysfunction. In this paper, we review and illustrate the indications to CEUS in the post-KT setting, as well as the main CEUS findings that can help establishing the diagnosis and planning the most adequate treatment.

Evolving Medical Imaging Techniques for the Assessment of Delayed Graft Function: A Narrative Review

“…A transplant affected by chronic rejection shows weaker, inhomogeneous contrast enhancement with a lower and delayed TTP, PI, and overall AUC. 60 Generally, in kidneys exhibiting DGF, the corticomedullary phase of the CEUS enhancement appears later and with lower AUC values than normal grafts, suggesting decreased vascular volume. 75 …”

“…The CEUS imaging is gaining ever-increasing acceptance to complement the low specificity of Doppler US imaging in the kidney transplantation setting. 60 The core premise behind CEUS is the use of US contrast agents as shown in Figure 4A . These are micrometer-sized (1-10 µm diameter) bubbles made from an inert lipophilic gas core, stabilized by a lipid, protein, or polymer outer shell.…”

“…The benefits of CEUS include (1) its portability allowing for examinations to be conducted at the patient’s bedside while MRI requires transport of patients to the radiology department where MRI machines are housed 60 ; (2) CEUS examinations are shorter and provide real-time representation of the distribution of the gas-filled contrast agents in the kidney microvasculature, whereas multiparametric MRI provides representative images at predefined timepoints; and (3) CEUS is more readily accessible. The MRI has a larger upfront expense and significant maintenance costs.…”

Thrombose veineuse précoce du greffon rénal : quelle prise en charge ?

“…Toutefois De plus, le délai de prise en charge n'a pas été relevé dans notre étude. Mais devant un probable doute à l'échographie (25), 41,8 % des patients ont bénéficié d'une autre imagerie (angioscanner ou IRM) ce qui prolonge le délai de prise en charge. On a donc évalué la survie du greffon en fonction du nombre d'examen radiologique réalisé.…”

Contrast-Enhanced Ultrasound in Children: Implementation and Key Diagnostic Applications

“…12)], demonstrate renal infarction, and diagnose pyelonephritis and renal abscess [91]. In adults, evaluation of renal transplant complications, including vascular complications, can be safely performed with CEUS, although further study is needed in children [92]. Additional future study in children should include the sensitivity of CEUS for nephrogenic rests and the ability to distinguish nephrogenic rest from Wilms tumor.…”