The Effect of Pulse Sequence Parameters and Contrast Agent Dose on Percentage Signal Recovery in DSC-MRI: Implications for Clinical Applications

J.L. Boxerman; E.S. Paulson; M.A. Prah; K.M. Schmainda

doi:10.3174/ajnr.A3477

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Fig 1.
Three sample tumors (first column) with corresponding first-injection (middle column) and second-injection (third column) PSR maps. First-injection PSR progressively increases with increasing T1 weighting of methods A (first row), B (second row), and C (third row). Second-injection maps (all by using method D) have lower PSR with poor contrast between tumor and normal brain, despite flip angles and TEs identical to those in method C. Preload administration decreases T1 sensitivity and PSR contrast, regardless of flip angle and TE.
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Fig 2.
Sample first-injection (A) and second-injection (B) signal-time curves for tumor and normal brain by using methods C and D (α = 90°, TE = 30 ms). Without preload (A), tumor PSR is >100%, whereas with preload (B), tumor PSR is <100%. First-injection PSR (method C) is significantly larger than second-injection PSR (method D) for both tumor (C; P = .037) and normal brain (D; P < .001) by using the 2-tailed paired t test.
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Fig 3.
Comparison of PSR in tumor (A) and normal brain (C) for methods A-C and in tumor (B) and normal brain (D) for second-injection method D grouped by first-injection method. There is a significant main effect of method groupings on first-injection tumor PSR (A; P = .0012), with PSR monotonically increasing with T1 weighting and no significant main effect on first-injection normal brain PSR (C; P = .93). There is no significant main effect of first-injection method groupings on second-injection PSR for tumor (B; P = .95) or normal brain (D; P = .13).

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Table 1:
Summary of DSC-MRI pulse-sequence parameters compared in this study
MRI Method No. Preload (mmol/kg) Bolus (mmol/kg) α (°) TE (ms)
A 7 0 0.1 35 54
B^{^a} 5 0 0.1 72 30
C 10 0 0.1 90 30
D 22 0.1 0.2 90 30
↵a Second echo of a dual-echo acquisition (first-echo TE = 3.3 ms); other methods were single-echo acquisitions. All methods used gradient-echo EPI.

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Table 2:

Mean PSRs grouped by DSC-MRI acquisition method

MRI Method^{^a} (Inj1, Inj2)	Tumor Characteristics					Mean PSR (% ± SEM)
	Tumor Characteristics					1st Injection		2nd Injection
	No.	GIII	GIV	New	Rec	Tumor	Normal	Tumor	Normal
A, D	7	1	6	1	6	91 ± 10	96 ± 5	81 ± 10	96 ± 8
B, D	5	1	4	0	5	217 ± 32	103 ± 14	76 ± 8	78 ± 4
C, D	10	5	5	7	3	372 ± 122	95 ± 2	79 ± 8	80 ± 2

Note:—SEM indicates standard error of the mean; Inj1, injection 1; Inj2, injection 2; GIII, grade III gliomas; GIV, grade IV gliomas; New, treatment-naïve or residual postoperative; Rec, recurrent (after conventional chemoradiation).
↵a MRI methods refer to first-injection and second-injection acquisition techniques for each patient (Table 1).