DOI: 10.5281/zenodo.18460613
title: i3M data for A4IM project

description: The images obtained at i3M (Valencia, Spain) has been acquired in a MRI prototype called Physio1. This system is a compact low-field MRI scanner based on a 72 mT Halbach permanent magnet, with a total weight of 250 kg. It is conceived as a portable and low cost (<50 k€) system, suitable for operation indoors, outdoors, and even at a patient’s home, and specifically designed for musculoskeletal imaging, particularly of joints, arms, and legs. The control system is built upon the MaRCoS project and is managed using a RedPitaya 122-16 together with an OCRA1 board, enabling flexible pulse sequence development and hardware control. User interaction with the system is performed through the MARGE environment. Physio1 is equipped with three cylindrical gradient coils capable of delivering gradient strengths of 25 mT/m along the x-axis and 40 mT/m along the y- and z-axes. For knee imaging, the system employs two single-channel RF coil designs based on Litz wire—one stretchable and one rigid—both used for transmission and reception. The qualitative data here presented have been acquired using the streachable coil, meanwhile data for relaxation mapping was measured using the rigid model.

All the data were generated using seven volunteers. Anonymized information on the sex, age, height, and possible knee injuries of the volunteers scanned for this database is provided below. The subject numbering used here corresponds to the numbering specified in the folder and file names of this database.Subject 1: Female. 34 years. 170 cm. Without injuries/anomalies in any knee.Subject 2: Female. 27 years. 160 cm. Without injuries/anomalies in any knee.Subject 3: Male. 31 years. 174 cm. Baker cyst in the upper region of left knee.BSubject 4: Male. 24 years. 185 cm. Without injuries/anomalies in any knee.Subject 5: Male. 24 years. 185 cm. Remanences of Osgood-Schlatter in right knee.Subject 6: Male. 30 years. 172 cm. Slight wear of both menisci due to sports practices.Subject 7: Female. 36 years. 160 cm. Without injuries/anomalies in any knee.

For a given subject acting as a volunteer, we distinguish between the application of (a) a qualitative protocol and (b) a quantitative protocol. The qualitative protocol consists of running three consecutive 3D RARE sequences, conveniently optimized to obtain PD-, T1-, and T2-weighted images. This protocol requires approximately 25 minutes of sequence execution time. The quantitative protocol consists of acquiring two sets of images: (1) five 3D RARE sequences with varying effective echo times (TEeff) to obtain a three-dimensional T2 map, and (2) seven 3D STIR sequences with varying inversion times to obtain a T1 map. Each image set is acquired for the same subject in separate sessions due to the long scanning times required for the quantitative protocol. In the tables below are listed the main parameters of the sequences performed for both protocols.

Table 1. Sequence parameters for qualitative protocol






 



PD-w



T1-w



T2-w





Naverages



1



8



2





FOV (cm)



(24, 18, 16)



(24, 18, 16)



(24, 18, 16)





Matrix size



(160, 120, 32)



(160, 120, 32)



(160, 120, 32)





Resolution (mm)



(1.5, 1.5, 5)



(1.5, 1.5, 5)



(1.5, 1.5, 5)





{Rd, Ph, Sl}



{x,y,z}



{x,y,z}



{x,y,z}





ETL



4



6



10





RF phase convetion



CPMG



CPMG



CPMG





TE/TEeff (ms)



10/10



20/20



20/100





k-Space trayectory



Center-out



Center-out



Out-center





Inversion time (ms)



0



0



0





Repetition time (ms)



800



150



1000





Acquisition time (ms)



4



4



4





BWacq (kHz)



40



40



40





Dummy pulses



5



20



0





Greph, rd time (ms)



5.5



5.5



5.5





Gdep, rd time (ms)



1



1



1





Gdep, ph/sl time (ms)



1



1



1





Slice zero filling (%)



35



35



35





Tscan (min)



8.3



8.3



8.3





 

Table 1. Sequence parameters for quantitative protocol






 



3D STIR for T1 mapping



3D RARE for T2 mapping





Naverages



1



1





FOV (cm)



(24, 18, 16)



(24, 18, 16)





Matrix size



(160, 120, 32)



(160, 120, 32)





Resolution (mm)



(1.5, 1.5, 5)



(1.5, 1.5, 5)





{Rd, Ph, Sl}



{x,y,z}



{x,y,z}





ETL



4



4





TE (ms)



10



{10, 25, 50, 75, 100}





TEeff



10



{10, 25, 50, 75, 100}





k-Space trayectory



Center-out



Center-out





Inversion time (ms)



{0, 40, 80, 120, 160, 200, 500}



0





Repetition time (ms)



800



800





Tacq (ms)



4



4





BWacq (kHz)



40



40





Dummy pulses



5



5





Greph, rd time (ms)



5.5



5.5





Gdep, rd time (ms)



1



1





Gdep, ph/sl time (ms)



1



1





Slice zero filling (%)



35



35





Tscan (min)



8.3



8.3





Number of images



7



5





Tprotocol (min)



58



41





 

Deeper details can be found in the couple of files attached here:

1) Useful information for data users.pdf

2) In vivo imaging with MRILab’s Physio 1 Scanner