0.55T cine, T1 and T2 mapping of the heart (iHEALTH)

Information for Users

Scanner

The MRI scanner used to acquire the data is the MAGNETOM Free.Max 0.55T commercial system manufactured by Siemens Healthineers (Erlangen, Germany), which received FDA clearance in July 2021 (510(k) Number: K210611). The scanner was designed to be compact, lightweight, cost-effective and is intended for orthopedic practices and routine musculoskeletal imaging applications.

The scanner employs a superconducting magnet with DryCool technology to generate a main magnetic field (B₀) of approximately 0.55 T at the field of view. The magnet assembly weighs less than 3.5 metric tons, and the system has a height of less than 80 inches. The bore diameter is 80 cm, providing improved patient comfort and accessibility, which can be particularly beneficial for patients with claustrophobia or anatomical challenges. The large bore also facilitates heart imaging with flexible coil positioning.

The gradient system employs actively shielded gradient technology, with a maximum gradient amplitude of 22–26 mT/m, a maximum slew rate of 45–55 T/m/s, and a maximum field of view (FOV) of up to 50 cm. The Tx/Rx RF coil used to acquire the heart data is the Contour S Coil (Part Number: 11407176), a commercial 6-channel flexible receive coil manufactured by Siemens Healthineers (Erlangen/Forchheim, Germany).

The Contour S Coil has a blanket-like flexible design with dimensions of 45 cm × 27 cm (17.7 in × 10.6 in), providing patient comfort by adapting to body contours without the need for straps. The coil features an ultra-lightweight construction using soft materials. Its flexibility allows it to conform closely to the heart improving coil-to-tissue coupling and potentially maximizing the signal-to-noise ratio (SNR) compared with rigid coil alternatives.

The coil operates at the proton Larmor frequency corresponding to a magnetic field strength of 0.55 T (approximately 23.6 MHz). Its 6-element phased-array design enables parallel imaging acceleration, allowing reduced scan times while maintaining diagnostic image quality.

Control system and data acquisition

The MR system is controlled through the manufacturer's proprietary software platform, syngo MR XA60, which manages synchronized pulse-sequence execution and data acquisition. User interaction with the system is handled through the syngo MR user interface. Raw data was acquired in ISMRMRD format, while reconstructed images are available in DICOM format.

Subjects information

A total of 110 subjects were recruited for this dataset, and cardiac MRI scans were acquired from each subject. Written informed consent was obtained from all volunteers prior to imaging. Anonymous information regarding the sex, age, height, weight, and smoking status (smoker/non-smoker) of the volunteers included in the database is provided in the accompanying "csv" file (Metadata DB MRI - Heart_Zenodo). The subject numbering corresponds to the numbering specified in the folder and file names in this database.

Pulse sequences

The volunteers were scanned using a 10-minute protocol, as detailed in Table 1. The protocol was acquired using ECG triggering with the MRI-compatible Schiller MAGLIFE Serenity monitor and disposable electrodes (Cleartrace RTL 1700C-050). For each volunteer, the complete examination can be divided into two groups of sequences: (a) a 2D cardiac cine protocol and (b) a 2D mapping protocol.

The 2D cardiac cine protocol consists of three consecutive CINE sequences with Cartesian trajectories and optimized parameters to acquire cardiac cine images in four-chamber, two-chamber, and short-axis views.

The 2D mappinng protocol consists of two sets of images: (1) 2D Modified Look-Locker inversion recovery (MOLLI) imaging for T1 mapping, and (2) a T2-prepared balanced steady-state free precession (T2p-bSSFP) sequence for T2 mapping. Both sequences were acquired in the short-axis view. The 2D T1 and T2 maps were generated using the vendor's software package with deep learning (DL)-based reconstruction for the T1 and T2 contrasts, respectively, by fitting a three-parameter model to the MOLLI images and a T2 decay model to the T2p-bSSFP images. The calculated maps and their corresponding image contrasts are provided in this dataset. 

The acquisition times for each sequence included in both protocols are listed in Table 1. The main acquisition parameters for the sequences included in both protocols are listed in Tables 2 and 3. Representative example images for the qualitative and quantitative protocols are shown in Figures 1 and 2.

Table 1. Acquisition time per sequence.

Table 2. Sequence parameters for 2D cardiac cine protocol.