TABLE 1:

Delayed-Phase Ferumoxytol-Enhanced Neuroinflammatory MRI Protocol at 3 T

Characteristic	SWIa	T2-Weighteda	Contrast-Enhanced T1-Weighteda,b,c
Sequence	GRE	GE-EPI	TSEd
Plane	Axial	Axial	Any
Mode	3D	3D	3D
TR (ms)	26	> 2500	550–750
TE (ms)	20	80–120	Minimum
Inversion time (ms)	NA	NA	NA
Flip angle (°)	15	90/≥ 160	Defaulte
Matrix size
Frequency	≥ 256	≥ 256	256
Phase	≥ 256	≥ 256	256
No. of excitations	≥ 1	≥ 1	≥ 1
FOV (mm)f	210	240	256
Slice thickness (mm)	1	1	1
Interslice spacing (mm)	0	0	0
Other options	T2*-weighted sequence may be substituted but provides lower spatial resolution	NA	Consider fat saturation
Parallel imaging factorg	Up to 2	Up to 2	Up to 2
Estimated acquisition time (min)h	5–8	5–8	5–8

Note—Listed sequences are performed 24–48 hours after ferumoxytol contrast injection. Brain tumor imaging protocol–compliant MRI with gadolinium-based contrast agent performed before ferumoxytol infusion allows assessment of baseline T1 shortening, presence of SWI/T2* susceptibility, and gadolinium enhancement characteristics and allows calculation of ferumoxytol-based cerebral blood volume (CBV) and segregation and extravascular localization of ferumoxytol imaging (SELFI) maps. Ferumoxytol and gadolinium administration can occur within the same MRI examination because the times of brain parenchymal signal changes are dissimilar for the two agents. The dose of ferumoxytol depends on the clinical scenario. However, in the context of brain tumor neuroinflammation, a dose of 4–7 mg/kg (up to a total dose of 510 mg) provides for calculation of ferumoxytol-based CBV and SELFI maps and assessment of delayed enhancement on T1-weighted images. Ferumoxytol should be administered in a 1:4 ratio diluted with normal saline solution over 15 minutes. The patient should be observed for 30 minutes for contrast reaction. Ferumoxytol should be administered only when personnel and therapies are immediately available for the treatment of anaphylaxis and other hypersensitivity reactions. SWI = susceptibility-weighted imaging, GRE = gradient-recalled echo, GE-EPI = gradient-echo echo-planar imaging, TSE = turbo spin-echo, NA = not applicable. (Information derived from [40])

^aContrast-enhanced images should be obtained with parameters equivalent to those for unenhanced images.

^bTSE (Siemens Healthineers and Philips Healthcare) is equivalent to fast spin-echo (FSE; GE Healthcare, Hitachi, Toshiba Medical Systems).

^cObtained 24–48 hours after ferumoxytol contrast injection. Timing should be consistent across all MRI examinations.

^dAcceptable 3D T1-weighted TSE sequences include CUBE (GE Healthcare), SPACE (Siemens Healthineers), VISTA (Philips Healthcare), isoFSE (Hitachi), and 3D MVOX (Canon Medical Systems).

^eFlip angles for 3D TSE sequences (including CUBE and SPACE) are complicated because many use variable flip angle refocusing radiofrequency pulses to produce the desired image contrast. Investigators are encouraged to work with their vendors to determine the ideal parameters.

^fAs cited in prior consensus guidelines [40].

^gInvestigators are encouraged to work with their vendors to determine the best parallel imaging strategies, which may include simultaneous multislice imaging, controlled aliasing in parallel imaging resulting in higher acceleration, integrated parallel acquisition technique, GRAPPA, and turbo or other acceleration factors. High-performance MRI systems may be capable of higher acceleration factors.

^hImaging times provided are estimates only. Exact imaging times depend on individual MRI system and hardware performance capabilities.