Contrast-Enhanced Ultrasound CEUS: Protocol, Safety, and Indications AIUM 2024
What the AIUM 2024 Practice Parameter Changes
AIUM Practice Parameter for the Performance of Contrast-Enhanced Ultrasound, 2024 establishes CEUS as a standardized ultrasound examination, rather than an optional addition to grayscale scanning. The document outlines requirements for indications, preparation, technique, safety, dosing of ultrasound contrast agents, and reporting. The practical implication for the department: CEUS must have an indication, contrast administration protocol, trained performer, access to emergency care, and reproducible recording of key enhancement phases.
Clinical Indications
AIUM considers CEUS as a method for real-time perfusion assessment. The most typical clinical tasks: characterization of focal liver lesions, clarification of cystic-solid structure and vascularization of kidney and other organ formations, assessment of vascular complications, inflammatory and traumatic changes, intervention monitoring, and detection of active perfusion where conventional B-mode and Doppler are insufficient.
A separate registered direction is contrast-enhanced ultrasound cystourethrography in children with known or suspected vesicoureteral reflux. In cardiology, microbubble agents are used to enhance visualization of cardiac chambers and endocardial borders. For each organ, it is important to distinguish between registered use of a specific drug and locally permissible off-label use: the latter requires compliance with the institution's internal rules.
Who and Where to Perform CEUS
The examination is performed by a physician skilled in conventional ultrasound of the relevant anatomical area and principles of contrast-specific imaging. The facility must have equipment with CEUS mode, the ability to save cine loops, means for intravenous access or sterile intravesical administration, and a kit for managing hypersensitivity reactions. The department protocol pre-defines the drugs used, standard doses, flushing method, observation rules, and adverse event recording procedures.
Preparation Before Contrast Administration
Before contrast, conventional ultrasound of the area of interest is performed: B-mode, color and spectral Doppler if necessary, lesion measurements, description of echostructure, cystic and solid components, calcifications, gas, vascular network, and technical limitations. Then the clinical question, previous imaging, allergy history, and known hypersensitivity to the specific agent or its components are reviewed. Reliable venous access is required for intravenous CEUS, allowing bolus administration and flushing. For intravesical CEUS, bladder catheterization is performed under sterile conditions.
Routine creatinine measurement before CEUS is not required: microbubble ultrasound contrasts do not have the nephrotoxicity characteristic of iodine-based CT contrasts and are not gadolinium-based MRI agents. This is one of the key advantages of the method for patients for whom radiation exposure or contrast CT/MRI is undesirable.
Doses and Registered Regimens
AIUM emphasizes the need to use the drug, administration route, and dose according to the agent's instructions and the institution's policy. Below are the main numerical regimens important for general CEUS practice.
| Clinical Task | Agent and Route | AIUM 2024 Dose |
|---|---|---|
| Focal liver lesions, adults | Suspension sulfur hexafluoride lipid-type A microspheres, intravenous bolus | 2.4 ml |
| Focal liver lesions, children | Same agent, intravenously | 0.03 ml/kg, maximum 2.4 ml |
| Vesicoureteral reflux in children | Same agent, intravesically with bladder filling | 1 ml |
| Left heart chamber contrast, adults | Same agent, intravenously | 2 ml |
| Left heart chamber contrast, adults | Perflutren lipid microspheres, intravenously | 10 μl/kg |
| Left heart chamber contrast, adults | Perflutren protein-type A microspheres, intravenously | 0.5 ml |
The dose should not be automatically transferred between drugs: microbubbles have different shells, gas composition, concentration, and registered indications. If visualization is insufficient, repeat administration is possible only within the framework of the drug's instructions and local protocol.
Scanning Technique
After selecting the area of interest, the contrast-specific mode with low acoustic impact is activated to preserve microbubbles and visualize their nonlinear signal. Gain, focus, depth, and dynamic range are adjusted before injection. A dual-screen mode is useful: the grayscale image helps maintain anatomical orientation, while the contrast window shows perfusion.
Contrast is administered as a bolus followed by flushing, simultaneously starting cine loop recording or a timer. For liver and kidney lesions, it is important not to stop observation immediately after early enhancement: both the accumulation pattern and washout are diagnostically significant. If there are multiple lesions, an index area is selected in advance; panoramic scanning after the bolus may lead to missing the early phase in a key lesion. For intravesical studies, the appearance of microbubbles in the ureters and calyceal system during filling and voiding is recorded.
Safety and Contraindications
The main contraindication is known or suspected hypersensitivity to the chosen ultrasound contrast agent or its components. CEUS is not associated with ionizing radiation and does not require iodine-based or gadolinium contrast. Microbubbles are primarily excreted through the lungs as a gas phase and do not create clinically significant nephrotoxic load.
Nevertheless, CEUS remains a pharmaceutical intervention. The facility should have trained personnel, the ability to monitor as clinically necessary, and medications for treating hypersensitivity reactions. Any itching, urticaria, bronchospasm, hypotension, chest pain, dyspnea, or vasovagal episode should be documented in the medical record with the agent and dose specified. Decisions on CEUS in pregnant, lactating, and unstable patients are made based on the balance of benefit and risk, considering the specific drug's instructions and alternative methods.
Documentation and Conclusion
The CEUS report should be standalone and verifiable. It must include the indication, organ and area scanned, agent used, dose, administration route, number of administrations, technical quality, complications or their absence. In the lesion description, record the size on baseline ultrasound, enhancement pattern relative to surrounding tissue, presence or absence of washout, necrosis, septa, solid components, vascular pedicle, mural nodules.
The conclusion should answer the clinical question: for example, typical benign pattern, suspicion of malignancy, absence of perfusion in the cystic component, viable tissue post-ablation, signs of reflux. If the study is limited by depth, gas, obesity, motion, inability to maintain focus, or inadequate contrast, this should be explicitly reflected in the protocol.
Practical Implementation Checklist
- Approve the list of indications and drugs for each facility.
- Set up CEUS presets and report templates for liver, kidneys, urinary tract, and interventions.
- Train staff in contrast preparation, bolus administration, flushing, and cine loop recording.
- Store in the report the dose, administration route, and information on adverse reactions.
- Regularly compare CEUS with CT, MRI, surgical, and morphological data for quality control.
Frequently asked questions
Is it necessary to check creatinine before CEUS?
Routinely no. Ultrasound microbubble contrasts are not iodine-based or gadolinium-based agents and do not have clinically significant nephrotoxicity.
Can the same dose be used for different ultrasound contrasts?
No. The dose depends on the specific agent, its concentration, registered indication, and administration route. AIUM requires following the drug's instructions and local protocol.
What must be included in the CEUS protocol?
Indication, organ examined, contrast name, dose, route and number of administrations, technical limitations, enhancement and washout characteristics, complications or their absence, and the final diagnostic conclusion.