LGE gadobutrol dose CMR in chronic MI (San Donato)

A retrospective single-centre cohort from IRCCS Policlinico San Donato near Milan of patients with chronic myocardial infarction who had contrast-enhanced cardiac MRI with gadobutrol between March 2014 and May 2018. The study compared how well the infarct scar stands out on late gadolinium enhancement (LGE) images when the patient received 0.10, 0.15 or 0.20 mmol/kg of contrast agent. The dose depended on the attending physician, not on the patient. A Zenodo record with the study title was published in February 2021; its files are restricted and not listed, and the data are shared on a motivated request.

Composition

79 patients with one examination each: 22 received 0.10 mmol/kg, 26 received 0.15 mmol/kg and 31 received 0.20 mmol/kg. Of 124 patients first retrieved, 35 were dropped because the infarct was not transmural and 10 because of artefacts on the LGE images. Patients with oedema (acute infarction) or small scars were not included. Most patients were men (90 to 95% per dose group), and median age per group ranged from 60 to 68 years.

Acquisition

All scans ran on a 1.5 T Siemens Magnetom Aera with an 18-channel coil, breath-holding and ECG gating. The protocol had short- and long-axis balanced SSFP cine images and a 2D segmented inversion-recovery gradient-echo LGE sequence covering the left ventricle (slice thickness 8 mm, flip angle 25 degrees). The delay before LGE was adapted to the dose.

Annotations

Left ventricular volumes, mass and ejection fraction were measured from cine images in QMass. On LGE images, scar was segmented with a 6 standard deviation threshold and corrected by hand, then given as a percentage of myocardium. Signal- and contrast-to-noise ratios were computed from regions of interest, and each exam received a four-level visual quality score.

Known limitations

• The image files are not openly available, and neither the record nor the paper says whether shared data include images.
• Single centre, single scanner and a single contrast agent; transmural infarcts only.
• Dose was not randomised.