Table 3.
Modalities and techniques for cardiovascular and renal imaging related to cardiorenal syndrome.
| Ultrasonography | Magnetic Resonance Imaging | Computed Tomography | Nuclear Imaging | |
|---|---|---|---|---|
| Assessment of Heart | ||||
| Conventional | 1. 2-dimentioanl measurement of cardiac chamber size, estimation of ventricular function 2. Valvular morphology and function, ventricular wall motion 3. Estimation of hemodynamic biomarkers by Doppler imaging |
1. Gold-standard measurement of chamber size and volume, ventricular systolic function, myocardial mass by cine imaging 2. Moderate to severe valvular abnormalities 3. Quantification of myocardial perfusion with contrast agent and/or vasodilator 4. Quantification of myocardial fibrosis and infiltration by late gadolinium enhancement |
1. Calculation of calcium score 2. Evaluation of coronary artery morphology by CT coronary angiography using contrast agent |
1. SPECT myocardial perfusion imaging is the most commonly used tool to diagnose coronary artery disease in CKD 2. Absolute quantification of myocardial blood flow by PET 3. Coronary flow reserve and stress myocardial perfusion by PET |
| Advanced | 1. 3-dimentional measurement of ventricular volumes and myocardial mass 2. Ventricular strain quantified by speckle-tracking 3. Improved structural and functional evaluation using ultrasonic enhancing agent |
1. Non-contrast quantification of myocardial infiltration/deposition by T1 mapping and T2(*) mapping 2. Myocardial infiltration/deposition by extracellular volume fraction with contrast agent 3. Ventricular strain quantified by feature/tissue tracking 4. Non-contrast assessment of myocardial perfusion by dobutamine inotropic stress CMR, MR-compatible exercise stress CMR, myocardial ASL 4. Myocardial hypoxia by BOLD, diffusion by DWI, diffusion anisotropy by DTI |
1. Functional imaging and myocardial perfusion using contrast agent 2. CT angiography-based fractional flow reserve of coronary arteries 3. Myocardial infiltration/deposition by extracellular volume fraction with contrast agent |
1. PET quantitative analysis of myocardial glucose utilization 2. SPECT evaluation of myocardial fatty acid oxidation 3.Hybrid imaging such as SPECT-CT, PET-CT, PET-MRI can generate multiple biomarkers in one scan |
| Assessment of kidneys | ||||
| Conventional | 1. Kidney length, estimated volume and echogenicity of cortex and medulla 2. Identify obstruction 3. Renal resistive index |
1. Volumetric measurement 2. Depiction of renal cortex and medulla by conventional T1-weighted and T2-weighted imaging |
1. Preferred for evaluation of kidney stones 2. Quantification of renal perfusion and GFR using contrast enhanced CT |
1. Differential diagnosis of AKI (prerenal AKI or acute tubular necrosis or postrenal AKI) by renal scintigraphy 2. Measurement of GFR 3. Measurement of renal blood flow |
| Advanced | 1. Intrarenal blood flow pattern 2.Renal venous blood flow, renal venous impedance index, renal venous discontinuity 3. Ultrasonic enhancing agent to assess renal perfusion |
1. Parenchymal oxygenation by BOLD 2. Noncontrast renal perfusion by ASL 3. Microstructural changes evaluated by DWI, DTI and T1/T2 mapping 4. Quantification of renal perfusion and GFR using dynamic contrast enhancement |
1. Dual energy CT for tissue characterization | 1. Renal SPECT-CT for assessment of GFR 2. Renal PET with novel radiotracers for faster and more accurate quantification of GFR |
| Radiation | None | None | Yes | Yes |
| Contrast agent and safety | Mirobubbles to enhance ultrasound signals; safe |
Gadolinium-based contrast agents, associated with nephrogenic systemic fibrosis, not applicable in patients with AKI and ESRD | Iodinated contrast agents, increase the risk of contrast-induced nephropathy in patients with renal dysfunction | Radionuclide labeled agents, safe. |
| Strengths in assessment of cardiorenal syndrome | 1. Most versatile, accessible and cost effective modality to evaluate the heart and kidneys simultaneously. 2. Doppler imaging may generate hemodynamic biomarkers for diagnosis, prognosis and therapeutic evaluation, especially for acute CRS. 3. Suitable for serial imaging across the natural history of CRS |
1. The most promising one-stop modality to evaluate structure, function and microstructural alterations in both heart and kidneys 2. Unique ability of quantitative assessment of fibrosis in both organs. Multiparametric scan to evaluate diffused infiltration/deposition, changes in perfusion, diffusion and oxygenation of heart and kidneys. 2. With consistent scan parameters and no radiation, non-contrast MRI is ideal for longitudinal tracking of cardiac and renal pathophysiological changes |
Most widely used noninvasive technique for anatomical assessment of coronary artery disease | Important modality for evaluation of myocardial perfusion in coronary artery disease in patients with CKD, without the use of toxic contrast agent. |
| Limitations | Can be compromised by inadequate acoustic window, poor Doppler signals and operator-dependent variations | Expensive, prolonged acquisition time, requiring high compliance of patient, complicated post-processing procedures | Not suitable for longitudinal serial evaluation due to radiation, limited utility without contrast agent | Not suitable for longitudinal serial evaluation due to radiation, low spatial resolution, prolonged acquisition time, limited utility and accessibility |
SPECT, Single-photon emission computed tomography; PET, positron emission tomography; CMR, cardiovascular magnetic resonance; CT, computed tomography; BOLD, blood oxygen level dependent; ASL, arterial spin labeling; DWI, diffusion weighted imaging; DTI, diffusion tensor imaging; AKI, acute kidney injury; CKD, chronic kidney disease; ESRD, end stage renal disease; GFR, glomerular filtration rate.