Medical Metrology

MRI lab

In Berlin-Charlottenburg PTB's MRI group is running a 3-tesla whole-body MRI scanner. Technical developments and phantom measurements are either done autonomously or in cooperation with external partners from science or industry. Clinical studies or other investigations involving human volunteers are carried out together with medical research groups.

3-tesla scanner
Transmit and receive system
RF coils
CW transmit system for SAR measurements
Laboratory for RF technology and coil development

3-tesla MRI scanner

Siemens Verio whole-body scanner

Manufacturer	Siemens
Installation	December 2009
Static field	2.89 T
Mass	8.3 t
Dimensions	L × W × H = 163 cm × 230 cm × 222 cm
Free bore	70 cm
He reservoir	1500 L
ΔB₀/B₀	±1.4 ppm (ø 40 cm)
Drift	0.1 ppm/h
Gradients	45 mT/m
Slew rate	200 T/m/s
¹H frequency	125.2 MHz

Transmit and receive system

Single-channel transmission (¹H)

Frequency	123,2 MHz
RF amplifier	Astex RFPA
Peak power	35 kW

Single-channel transmission (X nuclei)

Frequency range	30 − 130 MHz
RF amplifier	Dressler LPPA 13080W
Peak power	8 kW

Transmit array (¹H)

Channel	8
Frequency	123,2 MHz
RF amplifier	Analogic AN8135-S8
Peak power	8 kW per channel
Special features	each channel individually programmable in amplitude, frequency, and phase
	8-channel RF supervisor for patient safety
Installation	February 2010

Receive system

Channel	32
Frequency range	500 Hz − 1 MHz
Sampling rate	10 MHz
Resolution	32 Bit
Preamplifier	Noise factor > 0,5 dB
	Bandwidth 665 kHz

RF coils

Description	Manufacturer	Type	Properties
Body coil	Siemens	Tx/Rx	16-rung high-pass birdcage, circularly (head) or elliptically (body) polarized
12-channel head coil	Siemens	Rx
32-channel head coil	Siemens	Rx
4-channel neck coil	Siemens	Rx
24-channel spine coil	Siemens	Rx
16-channel cardio coil	In Vivo	Rx	front part
4-channel flex coil big	Siemens	Rx
4-channel flex coil small	Siemens	Rx
15-channel knee coil	QED	Tx/Rx
Ring coil	Siemens	Rx	ø 11 cm
CP head coil	Rapid Biomedical	Tx/Rx	16-rung birdcage

Broadband CW transmit system

Channels	2
2-channel synthesizer	PTS D310, 1 − 310 MHz
RF amplifier I	2 x Ophir 5052, 0.15 − 230 MHz, 200 W
RF amplifier II	2 x home built, 100 − 500 MHz, 200 W
Year of installation/upgrade	2001/2005
Applications	RF induced heating of phantoms by MRI transmit coils (B₀ = 0 − 11.7 T) in order to characterize these coils with respect to the SAR distributions they generate. The specific absorption rate SAR is a measure for the potential safety hazard due to RF-power absorption.

Laboratory for RF technology and coil development

Tasks

Development and manufacturing of receive- and transmit coils for high and ultrahigh field MRI
Testing and characterization of MRI coils, especially multi-channel transmit coils
Assembly and characterization of specific RF components (preamps, tuning and matching circuitry, ...)
Measurements of dielectric properties of phantoms
Maintenance and service for the MRI scanner

Contact

Frank Seifert