Microwave breast imaging: A review of clinical potential and technological advances

Table 5 System specifications and clinical readiness of institution-based radar-based microwave breast imaging systems

Institution	Antenna setup	Frequency range (GHz)	Patient orientation	Coupling medium	System configuration	Imaging technique	Development phase
Bristol (United Kingdom)-MARIA[25]	60 wide-slot antennas	3.0-8.0	Prone	Paraffin oil, wax, aqueous media	Stationary, 16-port Keysight VNA	Modified delay-and-sum	Near product launch
Calgary (Canada)-TSAR[26]	Monostatic antipodal Vivaldi	0.05-15.0	Prone	Canola oil	PC-controlled synthetic array, laser	Confocal DAS, skin artifact correction	Verification and validation
McGill (Canada)[44]	16 resistively-loaded traveling wave antennas	2.0-4.0	Prone	Ultrasound gel	Oscilloscope and pulse generator array	Delay-multiply-and-sum	Early feasibility
Galway (Ireland)-Wavelia[45]	18-element Vivaldi array	1.0-4.0	Prone	Liquid	Stationary array with VNA	TR-MUSIC (time-reversal method)	Verification and validation
Chalmers (Sweden)[46]	20 monopole antennas	0.2-3.0/0.5-6.0	Prone	Air or oil-filled phantom	Off-the-shelf SDR components	Confocal DAS or no imaging	Feasibility
Perugia (Italy)–Mammowave[47]	1 horn + 1 microstrip monopole	1.0-9.0	Prone	Air	Cobalt C1209 and Copper M. VNA	Huygens-based approach	Verification and validation
Hiroshima (Japan)[48]	4 × 4 dome-shaped array	3.1-10.6	Supine	Glycerine	UWB CMOS synthetic array	Confocal DAS	Verification and validation
São Paulo (Brazil)[49]	Dual-patch bistatic array	5.0-7.0	Fowler	Silicone rubber interface	UWB transceiver setup	Enhanced confocal DAS	Feasibility

VNA: Vector network analyzer; DAS: Delay-and-sum; TR-MUSIC: Time-reversal multiple signal classification; SDR: Software defined radio; UWB: Ultra-wideband; CMOS: Complementary metal-oxide-semiconductor; MBI: Microwave breast imaging.