Table 1.

Potential modifications to CT and MRI technique in the presence of metal artefact after surgery for rotator cuff disease

Technique	Modifications
CT	Acquisition factors to be considered:a decrease pitch; increase peak kilovoltage; increase milliamperage per second; use large focal spot
	Reconstruction algorithms: use soft tissue filter; reconstruct thicker slices, iterative reconstruction
	Display: use wide display window; create multiplanar three-dimensional images to reduce the display of artefact
MRI	3 T is feasible, but with extensive metal artefact use 1.5 T
	Avoid parallel imaging as there is a reduction in signal-to-noise ratio
	Pulse sequence choice:
	Fast spin echo favoured over gradient echo (although gradient echo is not as commonly used in shoulder protocols)
	Intermediate-weighted images are used for maximal signal-to-noise ratio, with echo times in the mid-30 s to mid-40 s
	Fat-suppression technique choice:
	Frequency selective fat suppression is feasible, but always compared with non-fat-suppressed images
	Inversion recovery favoured over frequency-selective fat suppression with the presence of heavy metal; however, in many cases, fat-suppressed imaging can still be used without sacrificing detail around the rotator cuff
	Pulse sequence parameter choices:
	Frequency and phase direction can be swapped
	Use longer echo train length
	Use shorter echo time
	Field of view, slice thickness, and matrix size altered to create small voxels (high spatial resolution)
	Increase bandwidth
	Increase signal averages
	Consider contrast (MR arthrography)
	Consider another modality: CT or ultrasound

Other modifications to the reconstruction and display should be favoured over increasing the dose.

^aModifications to acquisition parameters should be made sparingly, as these increase the radiation dose delivered to the patient.