India ink artifact: the black outline on opposed-phase images
A thin black line around organs on opposed-phase gradient echo is expected, and it is useful. This is where it comes from.
Chemical shift type 2 (India ink / opposed-phase)
A thin black outline around organs and around fat-containing lesions on GRE images.
At an opposed-phase TE, voxels containing both fat and water cancel. GRE has no 180° pulse to rephase them.
- Choose an in-phase TE (about 4.4 ms at 1.5 T, 2.2 ms at 3 T)
- Use a spin-echo sequence
- Use fat suppression
This effect is also diagnostic: signal drop on opposed-phase proves intracellular fat (liver steatosis, adrenal adenoma). Do not remove it from those protocols.
This page is one entry from the MRI Technologist Reference
The full reference has 31 protocols, 9 dynamic study timelines, 19 artifacts, 16 scanner problems and 15 safety topics, as a PDF in English and Arabic plus an interactive tool.
Educational reference. It does not replace your site protocols, the radiologist's instructions, the MR safety officer, or the manufacturer's instructions for any implant, device or contrast agent. Parameter values are typical starting points at 1.5 T and must be adapted to the scanner, coil and patient.