Imaging
Imaging Patients with Kidney Disease—Weighing the Risks and Benefits Jeffrey M Turner, MD1
and Mark A Perazella, MD, FASN2 1. Instructor in Medicine; 2. Professor of Medicine, Section of Nephrology, Department of Medicine, Yale University School of Medicine
Abstract
In recent years, clinicians have attempted to develop a rational strategy for imaging patients with kidney disease. Weighing the high number of comorbidities prevalent in this population against specific imaging-associated risks, such as nephrogenic systemic fibrosis and radiocontrast-induced nephropathy, is a challenging balancing act. In response to adverse events, reflexive shifts in imaging practices, in an attempt to improve patient care and reduce complications, have sometimes missed their mark. In particular, the risk of underdiagnosing or completely missing serious diseases has not been well appreciated in this setting. When deciding upon the optimal imaging modality for patients with kidney disease, it is imperative to make decisions based on a critical review of available data. Only then can a logical approach be taken. In difficult, high-risk situations, a discussion of the risks and benefits with the patient is required. In this article, we highlight key concepts that will hopefully assist clinicians in identifying patients at high risk of developing contrast-related complications. We offer insights into available non-contrast alternative techniques and prophylactic measures.
Keywords
Chronic kidney disease, nephrogenic systemic fibrosis, radiocontrast-induced nephropathy, gadolinium, magnetic resonance imaging, computed tomography
Disclosure: The authors have no conflicts of interest to declare. Received: September 14, 2011 Accepted: October 28, 2011 Citation: US Nephrology, 2011;6(2):131–7 Correspondence: Mark A Perazella, MD, FASN, Professor of Medicine, Section of Nephrology, Department of Medicine, Yale University School of Medicine, Boardman Building 11, 330 Cedar Street, New Haven, CT 06520-8029. E:
mark.perazella@
yale.edu
Patients with acute or chronic kidney disease present unique concerns for the clinician when it comes to selecting an imaging modality. This population has a high incidence of life-threatening morbidities that require accurate imaging to make the correct diagnosis; however, they also have a significant risk for serious adverse events associated with the administration of image-enhancing agents, namely iodinated radiocontrast and gadolinium-based contrast agents (GBCAs). The challenge for the clinician is to accurately assess the risks and benefits for each patient when choosing between the available imaging modalities. This incorporates many complex variables, which unfortunately has left the medical community with numerous concerns and uncertainties that have ultimately impacted clinical practice.
The appropriate use of the various imaging options in patients with underlying kidney disease is a rapidly evolving area of clinical medicine. The focal point within this evolution was the identification, in 2006, of GBCAs as the causative agent for nephrogenic systemic fibrosis (NSF).1 Prior to 2006, magnetic resonance imaging (MRI) with GBCAs was considered a relatively safe procedure in all patients, including those with underlying kidney disease. It gave clinicians an excellent imaging option for patients who were otherwise unable to undergo radiocontrast exposure, a well-known cause of acute kidney injury (AKI) in these patients. However, with the recognition of the link between GBCAs and NSF, a swift change in imaging practices subsequently occurred, driven
© TOUCH BRIEFINGS 2011
by concerns about the devastating consequences of NSF and the aggressive litigation pursued by malpractice lawyers. The ramifications of this pendulum swing have resulted in an overly conservative approach to the imaging of patients with kidney disease. One of the unfortunate consequences is the increased risk for missed diagnoses due to the avoidance of MRI enhanced with GBCAs.
This avoidance of GBCAs has also led to a greater reliance on radiocontrast-enhanced computed tomography (CT) for imaging patients with underlying kidney disease. In many situations, this may be an appropriate alternative; however, in certain circumstances, this creates suboptimal image quality and hence missed diagnoses. In addition, increased radiation exposure as well as allergic reactions and nephrotoxicity from radiocontrast exposure occur. This last complication is very relevant, as it has a number of acute and chronic ramifications. This is compounded by the fact that the prevention of radiocontrast-induced nephropathy (RCIN) is suboptimal, as clinical studies examining the efficacy of various prophylactic agents have yielded inconsistent results.
As clinical practice regarding imaging patients with renal impairment continues to evolve, clinicians must critically assess the data available in this area, thereby allowing the medical community to develop a reasonable strategy to accurately and safely image these patients.
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