MRI Site Planning & Installation Guide

Why Site Planning Matters

1. Site Layout & Room Design

Every MRI installation starts from a detailed site drawing covering the magnet room, control room, equipment room, and the access route from receiving to final position. For practical reasons the magnet room should sit near an exterior wall — the magnet is the heaviest piece of equipment that will ever pass through your facility, and exterior placement keeps delivery (and future replacement) simpler and cheaper.

The technologist must keep continuous visual contact with the patient, so a large RF-shielded observation window, a two-way intercom, and an emergency stop at the console are essential. Room layout should also support patient safety screening before anyone enters the magnet room.

Avoid carpet in the magnet, control, and equipment rooms — specify thin non-conductive vinyl (VCT) for clean magnet-skid movement, no static buildup, and easy cleaning.

2. RF Shielding

The RF shield is a continuous, electrically conductive copper or galvanized-steel envelope around the magnet room that blocks external RF noise and contains the MRI’s own transmissions. Done right it is invisible; done wrong it shows up as ghosting and banding in every image. The shield is grounded at a single point, continuous across walls/ceiling/floor, and fitted with a finger-stock RF door that opens outward for quench pressure equalization.

Every penetration is a potential antenna: electrical lines route through RF low-pass filters, gases and water through RF-sealed waveguides, HVAC through honeycomb waveguides, and data through fiber. The shield is tested twice — before delivery and after magnet placement — to a typical 90–100 dB shielding effectiveness across the imaging band.

3. Magnetic Shielding & Fringe Field

The 5-gauss line is the safety boundary for the magnetic fringe field and must be entirely contained within a controlled-access area — it cannot extend into a public corridor or occupied office. Unshielded, a 1.5T system’s 5-gauss line extends roughly 5 m radially and 9 m axially; on a 3T system those distances roughly double. Fringe fields are three-dimensional, so floors above and below need evaluation too.

Moving ferromagnetic mass (elevators, vehicles, HVAC chillers, light rail, structural steel) degrades magnet homogeneity and shows up as artifacts. Vibration sources — mechanical rooms, loading docks, traffic-bearing structures — must be designed around with isolation pads or reinforced slabs.

4. Electrical Requirements

A high-field MRI is one of the most electrically demanding systems in any facility, pulling continuous power for cooling plus sharp spikes during acquisition. All work must comply with the NEC and be performed by a contractor experienced with imaging installations.

A practical tip that pays off later: size the electrical service for a higher-performance gradient package than your initial purchase, so a future gradient upgrade does not require re-pulling conductors and disturbing the RF shield.

5. HVAC & Chilled Water

HVAC must run 24/7 — loss of cooling can trigger a gradient thermal shutdown or, in the worst case, helium boiloff or quench. Each room gets independent thermostatic control.

Most systems require continuous chilled water to the RCA cabinet: typically 5–15 GPM, 45–50°F supply, 40–80 PSI, pH 6.5–8.5, hardness below 100 ppm. A redundant chiller sized for the full load is strongly recommended — far cheaper than a quench and re-fill.

6. Cryogen Management & Quench Pipe

Superconducting magnets are cooled by liquid helium at ~4 Kelvin. During a quench, helium converts almost instantly from liquid to gas, expanding roughly 750-fold — it must vent safely outside through a dedicated quench pipe or it will displace breathable air in seconds.

Typical quench pipe: 8–12 inch stainless or aluminum, pitched to drain, discharging at least 10 ft above grade away from windows and intakes. An oxygen monitor in the magnet room alarms if levels drop during a release event.

7. Rigging & Delivery Day

A 1.5T magnet weighs 8,000–15,000 lb (3T systems 18,000+). Hire a rigger specifically experienced with MRI magnet handling, and have the OEM service engineer on site to oversee cold-head power continuity — loss of power lets the magnet warm and boil off helium, forcing a costly re-cool and re-fill. The rigger should walk the full route 4–6 weeks ahead.

8. MRI Safety Zones (ACR)

• Zone I — Unrestricted public area (waiting, reception); no screening required.
• Zone II — Reception & screening interface; patients screened for contraindications and metal.
• Zone III — Controlled operator area (console, control room); MR personnel only.
• Zone IV — The magnet room itself; the most restricted zone, active magnetic field, signage at every entry.

9. Project Timeline

A typical refurbished 1.5T installation runs 8 to 16 weeks from signed contract to first patient scan — a few weeks of equipment work and the majority site preparation: site survey and permits (wk 1–2), demolition and long-lead orders (wk 2–4), RF enclosure and rough-ins (wk 4–6), magnet delivery and rigging (wk 6–8), calibration and image-quality validation (wk 8–10), applications training and physicist inspection (wk 10–12), first patient scan (wk 12+).