Quantitative imaging in nephrology: limits and potentials of elastosonography

Abstract

Chronic kidney disease is characterized by increasingly amplified fibrotic processes regardless of etiology. The severity of renal fibrosis seems to correlate with an increased risk of end-stage renal disease; therefore, monitoring of renal fibrosis over time may play an important role in the follow-up of both focal and diffuse renal diseases and in evaluating the response to treatments. Renal biopsy is the only method capable of providing objective and comparable information on the extent of fibrosis, but it is not suitable for outpatient monitoring of chronic kidney disease due to its invasiveness. Elastosonography is an innovative and non-invasive ultrasound method that allows the measurement of tissue elasticity through the transmission of mechanical waves and the measurement of their propagation speed. Although some authors have demonstrated the usefulness of elastosonographic techniques for the quantification of liver fibrosis, few studies have investigated the applications of elastosonography in renal pathology. Furthermore, the depth of native kidneys, the high anisotropy of the renal tissue, and the possibility of examining only a small region of interest currently limit its spread in clinical practice. The aim of this review is to examine the physical principles of elastosonography and to review the latest evidence about the possible applications of the ARFI (acoustic radiation force impulse) technique in the study of kidney diseases.

Keywords: ultrasound, fibrosis, renal elastosonography, ARFI, quantitative imaging

Sorry, this entry is only available in Italian.

Introduzione

La malattia renale cronica (Chronic Kidney Disease, CKD) è una condizione patologica ad elevata prevalenza nella popolazione generale, caratterizzata da alterazioni della funzione renale e/o anomalie strutturali presenti per più di tre mesi, con variabile tendenza alla progressione verso forme più gravi di insufficienza d’organo [1]. Sebbene numerose patologie del parenchima, dei vasi o delle vie escretrici (sia primitive che secondarie) possano provocare la CKD, la fibrosi d’organo rappresenta la caratteristica comune a tutti i differenti meccanismi patogenetici responsabili di danno renale. Il grado di fibrosi sembra inoltre essere correlato con un maggior rischio di progressione verso l’End Stage Renal Disease (ESRD), pertanto possiede un elevato valore predittivo negativo per l’outcome delle patologie renali croniche [2]. 

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The new frontier in endovascular treatment of arteriovenous fistula stenosis: the role of ultrasound-guided percutaneous transluminal angioplasty

Abstract

Native arteriovenous fistula is the preferred vascular access because of it does not usually cause infections and seems to be closely related with prolonged patient survival, compared to prosthetic grafts and central venous catheters; it also is cost effective. Venous stenosis is one of the main causes of AVF failure. It is caused by a number of upstream and downstream events. The former group comprises hemodynamic and surgical stressors, inflammatory stimuli and uraemia, while downstream events involve the proliferation of smooth muscle cells and myofibroblasts and the development of neo-intimal hyperplasia. Percutaneous transluminal angioplasty is the gold standard for arteriovenous fistula stenosis. It allows the visualization of the whole vascular circuit and the immediate use of the vascular access for the next dialysis session. Ultrasound-guided percutaneous endovascular angioplasty is a feasible and safe alternative to conventional fluoroscopic technique: it is equally effective in treating arteriovenous fistula stenosis, but it presents the advantage of not using contrast media or ionizing radiation. The aim of this review is to report the latest evidence on cellular and molecular mechanisms that contribute to the development of neo-intimal hyperplasia, as well as the current and future therapeutic perspectives, especially concerning the use of anti-proliferative drugs, and the efficacy of the ultrasound-guided angioplasty in restoring and maintaining the vascular access patency over time.

Key words: Percutaneous angioplasty, ultrasound, arteriovenous fistula, hemodialysis, stenosis.

Sorry, this entry is only available in Italian.

Introduzione

La prevalenza della malattia renale cronica terminale aumenta di anno in anno. Nel 2010, il numero dei pazienti sottoposti a terapia emodialitica in tutto il mondo era pari a 2,618 milioni e, secondo alcune recenti stime, è destinato a crescere fino a 5,439 milioni entro il 2030 [1]. A livello nazionale, i dati estrapolati dal Report 2015 del Registro Italiano di Dialisi e Trapianto evidenziano un’incidenza e una prevalenza di 154 pazienti/pmp e di 770/pmp rispettivamente [2]. Indipendentemente dalla metodica utilizzata, il buon funzionamento dell’accesso vascolare (AV) rappresenta un requisito irrinunciabile per una ottimale adeguatezza dialitica. 

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Management of the incidental renal masses

Abstract

The diagnosis of renal masses has increased in the last decades owing to the widespread use of imaging (ultrasound, computed tomography and magnetic resonance).

Majority of the renal masses are detected incidentally on routine ultrasound examination.

Solid masses detected on ultrasound require further imaging evaluation with CT and/or MRI for suitable characterization. US-guided renal biopsy is a safe, effective and accurate method for evaluating the small renal masses with ambiguous radiologic findings.

Navigation technology and multimodality image fusion represent an important development in interventional radiology, especially for performing difficult percutaneous biopsies and ablations of small renal masses.

Multidisciplinary approach is required which results from experience and knowledge and in hard cases the use of serial imaging can be helpful.

 

Keywords: renal masses, imaging, ultrasound, renal biopsy, active surveillance

Sorry, this entry is only available in Italian.

Introduzione

Il riscontro di masse renali durante gli ultimi trent’anni è andato via via aumentando (1) grazie alla diffusione delle tecniche di imaging, in primo luogo l’ecografia (US), ma anche la tomografia assiale computerizzata (TC) e la risonanza magnetica nucleare (MRI).

 

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