Table 1.

“Ideal” recommended 3T metastatic brain tumor imaging protocol

	3D T1w TSE Preb	Ax 2D FLAIRj,q	Ax 2D DWIp,v		DSCa Perfusion (Optional)	Ax 2D T2wh,i,q	3D T1w TSE Postb
Sequence	TSEs	TSEc,s	SS-EPIg	Contrast Injection a	GE-EPI	TSEc,s	TSEs
Plane	Sagittal or Axial	Axial	Axial		Axial	Axial	Sagittal or Axial
Mode	3D	2D	2D		2D	2D	3D
TR [ms]	550–750	>6000	>5000		1000–1500	>2500	550–750
TE [ms]	Min	100–140	Min		25–35 ms	80–120	Min
TI [ms]		2000–2500k
Flip angle	Defaultt	90º/≥160º	90º/180º		30º	90º/≥160º	Defaultt
Frequency	256	≥256	128		≥96	≥256	256
Phase	256	≥256	128		≥96	≥256	256
NEX	≥1	≥1	≥1		1	≥1	≥1
FOV	256 mm	240 mm	240 mm		240 mm	240 mm	256 mm
Slice thickness	1 mm	3 mm	3 mm		3–5 mm as needed to cover tumor	3 mm	1 mm
Gap/spacing	0	0	0		0–1 mm as needed to cover tumor	0	0
Other options			b = 0, 500, 1000 s/mm2 ≥3 directions		30–60 pre-bolus time points; >120 total time points
Parallel imaging	Up to 3xu	Up to 2x	Up to 2x		Up to 2x	Up to 2x	Up to 3xu

Abbreviations: TR = repetition time; TE = echo time; TI = inversion time; NEX = number of excitations; FOV = field of view.

^a 0.1 mmol/kg dose injection with a gadolinium chelated contrast agent. Use of a power injector is desirable at an injection rate of 3–5 cc/sec. (Note: If DSC perfusion is collected, contrast injection is performed after starting DSC acquisition. DSC perfusion can be performed with the “ideal” protocol at 3T as well as with the minimum standard protocols at 3T and 1.5T.)

^b Post-contrast 3D T1-weighted images should be collected with equivalent parameters to pre-contrast 3D T1-weighted images.

^c TSE = turbo spin echo (Siemens & Philips) is equivalent to FSE (fast spin echo; GE, Hitachi, Toshiba).

^d FL2D = two-dimensional fast low angle shot (FLASH; Siemens) is equivalent to the spoil gradient recalled echo (SPGR; GE) or T1- fast field echo (FFE; Philips), fast field echo (FastFE; Toshiba), or the radiofrequency spoiled steady state acquisition rewound gradient echo (RSSG; Hitachi). A fast gradient echo sequence without inversion preparation is desired.

^e IR-GRE = inversion-recovery gradient-recalled echo sequence is equivalent to MPRAGE = magnetization prepared rapid gradient-echo (Siemens & Hitachi) and the inversion recovery spoiled gradient-echo (IR-SPGR or Fast SPGR with inversion activated or BRAVO; GE), 3D turbo field echo (TFE; Philips), or 3D fast field echo (3D Fast FE; Toshiba).

^f A 3D acquisition without inversion preparation will result in different contrast compared with MPRAGE or another IR-prepped 3D T1-weighted sequences and therefore should be avoided.

^g In the event of significant patient motion, a radial acquisition scheme may be used (eg, BLADE [Siemens], PROPELLER [GE], MultiVane [Philips], RADAR [Hitachi], or JET [Toshiba]); however, this acquisition scheme is can cause significant differences in ADC quantification and therefore should be used only if EPI is not an option. Further, this type of acquisition takes considerable more time.

^h Dual echo PD/T2 TSE is optional for possible quantification of tissue T2. For this sequence, PD is recommended to have a TE < 25ms.

ⁱ Advanced sequences can be substituted into this time slot, so long as 3D post-contrast T1-weighted images are collected between 4 and 8 min after contrast injection and this timing is constant across all MR exams performed in each patient.

^j 3D FLAIR is an optional alternative to 2D FLAIR, with sequence parameters as follows per EORTC guidelines: 3D TSE/FSE acquisition; TE = 90–140 ms; TR = 6000–10,000 ms; TI = 2000–2500 ms (chosen based on vendor recommendations for optimized protocol and field strength); GRAPPA≤2; Fat Suppression; Slice thickness ≤ 1.5mm; Orientation Sagittal or Axial; FOV ≤ 250 mm x 250 mm; Matrix ≥ 244x244.

^k Choice of TI should be chosen based on the magnetic field strength of the system (eg, TI ≈ 2000ms for 1.5T and TI ≈ 2500ms for 3T).

^l In order to ensure comparable SNR older 1.5T MR systems can use contiguous (no interslice gap) images with 5mm slice thickness or increase NEX for slice thickness ≤4mm.

^m For Siemens and Hitachi scanners. GE, Philips, and Toshiba scanners should use a TR = 5–15 ms for similar contrast.

ⁿ For Siemens and Hitachi scanners. GE, Philips, and Toshiba scanners should use a TI = 400–450 ms for similar contrast.

^p Older model MR scanners that are not capable of >2 b-values should use b = 0 and 1000 s/mm².

^q Axial 2D T2-weighted FLAIR and Axial 2D T2-weighted images can be interchanged pre- and post-contrast.

^r Sites may choose to perform the 3D T1w IR-GRE sequence prior to the 2D T1w TSE/SE because of the potential risk of patient movement and to help with patient comfort. However, there is less inherent lesion conspicuity in the 3D T1w IR-GRE sequence, so delaying this sequence to the end may be efficacious.

^s Acceptable 3D T1w TSE sequences include CUBE (GE), SPACE (Siemens), VISTA (Philips), isoFSE (Hitachi), or 3D MVOX (Canon)

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

^u Investigators are encouraged to work with their scanner vendors to determine the best parallel imaging strategies, which may include simultaneous multislice imaging (SMS), controlled aliasing in parallel imaging resulting in higher acceleration (CAIPI), iPAT, GRAPPA, as well as turbo or other acceleration factors.

^v While some sites may choose to collect DWI post-contrast, studies have suggested this can lower ADC measurements as much as 3%.¹⁵²