Role of imaging in the evaluation of renal dysfunction in heart failure patients

Table 1 Advantages and limitations of renal imaging techniques

	Clinical relevance	Advantages	Limitations
Bidimensional ultrasonography	Morphological evaluation (dimensions; echogenicity; corticomedullary ratio)	Fast; highly feasible in clinical practice; excludes obstructive uropathy and some parenchymal abnormalities	Nonspecific
Arterial RI (Doppler)	Indirect evaluation of arterial hemodynamics (resistances and vascular compliance) and parenchymal alterations	Fast; highly feasible in clinical practice; prognostic value	Influenced by renal obstructive arterial disease; lower accuracy with irregular rhythms
Venous pattern (Doppler)	Indirect evaluation of venous congestion, right atrial function and parenchymal compliance	Fast; highly feasible in clinical practice; prognostic value	Lack of standardization
Computed tomography	Evaluation of GFR through measurement of contrast wash-out	High spatial resolution	Nephrotoxicity of contrast media; radiation exposure
Nuclear imaging	GFR and RBF estimation through DTPA and MAG3 99mTC labelled uptake intensity measurement	Low radiation dose	Radiation exposure
MRI		No radiation exposure	Time consuming; expensive
Phase-contrast MRI	Evaluation of RBF	No use of Gadolinium	Breathing movement artefacts
Dynamic MRI	Evaluation of GFR through measurement of signal attenuation	Reliable	Particularly time consuming (> 70 min)
BOLD MRI	Evaluation of renal parenchymal oxygenation exploiting superparamagnetic properties of desoxyHb	No use of Gadolinium; unique method to assess this parameter	Lack of standardization; low signal change of BOLD effect; no clinical applications
MRI detectable nanoparticles	Evaluation of single-glomerulus volume and structural changes	No use of Gadolinium; unique method to image renal parenchyma at microscopic level	Prone to movement artefacts; possible toxicity of nanoparticles; no clinical applications

BOLD: Blood oxygen level dependent; GFR: Glomerular filtration rate; MRI: Magnetic resonance imaging; RBF: Renal blood flow.