How to Choose an MRI Shielding Vendor: Questions to Ask Before You Sign
The MRI shielding contractor you choose will have more influence over your scanner's long-term performance than almost any other installation decision you make. A failed RF cage, an under-designed passive shielding package, or a missed penetration discovered during acceptance testing can cost hundreds of thousands of dollars and months of delay. The contractor selection process is where you prevent those outcomes—not during remediation.
This guide gives you the specific questions to ask, qualifications to require, and red flags to watch for when evaluating MRI shielding vendors.
Why MRI Shielding Vendor Selection Is Different from Standard Construction Procurement
MRI shielding is a specialty trade with no close analog in general construction. RF cage installation requires precision metalwork, intimate knowledge of scanner-specific penetration requirements, and the ability to work within manufacturer tolerances that most general contractors have never encountered.
The consequences of poor vendor selection are also asymmetric. A failed RF shield can only be confirmed through testing—which happens after installation is complete. At that point, remediation involves disassembling completed work inside a room that may already have equipment in it. The cost and schedule impact typically dwarfs the original savings from selecting a cheaper contractor.
Essential Qualifications to Require From Any MRI Shielding Contractor
Manufacturer Approval and Experience Records
Major MRI scanner manufacturers—Siemens Healthineers, GE HealthCare, Philips, Canon Medical—maintain lists of approved shielding vendors for their products. Before evaluating any contractor, ask whether they have completed installations for your specific scanner model and manufacturer. Some manufacturers require contractor pre-approval for warranty purposes.
Require a minimum of 10–20 completed MRI shielding projects as a baseline. For 3T and above, require documented experience with that field strength specifically.
Reference Projects With Contact Information
Ask for three to five reference projects comparable to yours in scanner field strength, room complexity, and building type. Request names, institutions, and direct contact information—not just a project list. Call the references and ask specifically about whether the project met shielding performance specifications on first testing, and how the contractor handled any deficiencies.
Insurance and Bonding
MRI shielding contractors should carry general liability insurance of at least $2 million per occurrence, completed operations coverage, and workers' compensation. For projects involving design responsibility, verify that professional liability (errors and omissions) coverage is in place. Request certificates of insurance before contract execution, naming your organization as additional insured.
In-House Testing Capability
A contractor who can't test their own work creates a fundamental accountability problem. Require that the vendor perform acceptance testing using calibrated equipment traceable to NIST standards, and that they provide a formal shielding performance report referencing ASTM E1851 or equivalent methodology. Vendors who subcontract testing are not disqualified, but you should understand the relationship and who bears responsibility for deficiencies.
Technical Qualifications to Evaluate
Penetration Management Capability
The RF shield's integrity lives or dies at its penetrations—every pipe, conduit, HVAC duct, and cable entry point is a potential failure. Ask vendors how they document and manage penetrations during installation. A rigorous contractor maintains a penetration log that tracks every entry point, the waveguide filter or other treatment used, and the responsible tradesperson.
Door Specification Experience
RF shielded doors are the most mechanically complex and failure-prone element of the cage. Ask vendors which door manufacturers they work with, whether they install and adjust doors themselves or subcontract, and what their warranty process is for door-related shielding failures.
Passive Shielding Design Capability
If your project requires passive magnetic shielding, the contractor or their engineering team must be able to design a solution—not just install one. Ask whether they perform in-house passive shielding design, and if not, who their design engineering partner is and what that firm's credentials are. Fringe field modeling using finite element analysis should be standard for any 3T or above passive shielding project.
| Evaluation Criterion | Minimum Requirement | Best-in-Class Indicator |
|---|---|---|
| Completed MRI projects | 10+ projects | 50+ projects, documented by field strength |
| Reference availability | 3 references with direct contact | 5+ references, site visits offered |
| In-house testing | Performs own acceptance testing | NIST-traceable calibration records provided |
| Passive shielding design | Design partner named and qualified | In-house FEA modeling capability |
| Manufacturer relationships | Approved by scanner manufacturer | Preferred vendor status, multiple OEMs |
| Insurance | $2M GL, workers' comp, completed ops | Professional liability included |
Questions to Ask During the Interview Process
Beyond written qualifications, the vendor interview reveals how a contractor thinks about problems. Use these questions to separate experienced specialists from generalists attempting to enter the market.
"Walk me through how you would handle a penetration that wasn't on the drawings." A competent contractor describes a process: stop work, document the conflict, consult the shielding design, determine the correct waveguide filter or treatment, update the penetration log, and notify the project manager. An inexperienced contractor will describe improvising a solution.
"What would cause you to fail your own acceptance test, and what happens next?" Any contractor who claims they've never failed a test is either very new or not being candid. A good answer describes the specific causes of cage failures (usually doors or penetrations), the remediation process, and how warranty coverage works.
"How do you coordinate with the scanner manufacturer's site prep team?" MRI shielding installation must be precisely sequenced with magnet delivery, ramping, and site prep. A contractor who has done this before describes the coordination rhythm; one who hasn't will give a vague answer.
"What scanner-specific requirements does our model have that differ from your standard installation?" Different manufacturers have different requirements for waveguide filter specifications, minimum door dimensions, and penetration placement. A contractor familiar with your specific scanner model should be able to answer this from memory.
Contract Terms to Negotiate Before Signing
Shielding performance must be defined in the contract—not left to interpretation. Include specific acceptance criteria referencing the test standard (ASTM E1851 or equivalent), the required attenuation levels by frequency band, and what constitutes a passing result. Define who pays for re-testing if the cage fails initial acceptance.
Warranty terms should cover both materials and workmanship for a minimum of two years, with specific provisions for door mechanisms and gasket materials that are subject to wear. Penetration seals should be warranted for five years.
Retainage—typically 10%—should be withheld until after successful acceptance testing, not just substantial completion. This aligns the contractor's financial incentive with your performance standard.
Red Flags That Should End Vendor Consideration
Inability to provide direct reference contacts—only a project list—is a significant warning sign. Contractors with a strong track record have clients who will speak to them.
Subcontracting all testing to a third party with no accountability mechanism is problematic. The contractor should be responsible for the cage's performance, not just its installation.
Pricing that is 30% or more below the competitive range almost always means something is not included. Request a detailed scope breakdown to identify what's been omitted.
Unwillingness to specify acceptance criteria in the contract—or proposing criteria so vague they can't be failed—suggests the vendor expects deficiencies and is protecting themselves contractually.
Frequently Asked Questions About MRI Shielding Vendor Selection
How do I find qualified MRI shielding companies?
Start with your scanner manufacturer's list of approved or preferred shielding vendors. Ask your hospital architect or project manager for contractors they've worked with. Organizations like the American College of Radiology and ASHE (American Society for Health Care Engineering) can also provide referrals.
What MRI shielding contractor qualifications should I require?
At minimum: 10+ completed MRI installations, manufacturer approval for your scanner model, in-house acceptance testing capability with NIST-traceable equipment, general liability insurance of $2M+ per occurrence, and completed operations coverage. For 3T installations, require specific experience at that field strength.
What questions should I ask an MRI shielding vendor?
Ask about their penetration management process, how they handle discovered conditions, their experience with your specific scanner model, whether they've failed their own acceptance tests and how they resolved it, and how they coordinate with the scanner manufacturer's site prep team.
How do I evaluate an MRI shielding company's proposal?
Require itemized proposals that separate material costs, labor, door hardware, waveguide filters, testing, and commissioning. This makes scope comparison meaningful. Verify that acceptance criteria are explicitly stated and consistent across all proposals being compared.
Should I use a certified MRI shielding installer?
Manufacturer certification or approval is the most meaningful form of qualification for MRI shielding work—it indicates the contractor has installed that specific scanner model before. Industry-specific certifications can also be meaningful, but manufacturer approval is the more important threshold.
What is an MRI shielding RFP and what should it include?
An MRI shielding RFP is a formal request for proposal that solicits pricing and approach from qualified contractors. It should include site plans, structural drawings, scanner model and specifications, fringe field diagrams, proposed schedule, and specific requirements for qualifications, testing, and warranties.
How do I compare MRI shielding contractor bids?
Normalize bids by verifying scope inclusions: confirm each proposal covers the same materials (copper vs. steel, panel gauge), the same penetration count, the same door specification, testing, and warranty terms. Price differences that remain after normalization reflect labor rates, overhead, and margin—evaluate these in the context of the reference quality and track record.