Usefulness of Wave-CAIPI for Postcontrast 3D T1-SPACE in the Evaluation of Brain Metastases

H.J. Baek; Y.J. Heo; D. Kim; S.Y. Yun; J.W. Baek; H.W. Jeong; H.J. Choo; J.Y. Lee; S.-I. Oh

doi:10.3174/ajnr.A7520

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FIG 1.
Brain MR imaging of a 62-year-old male patient with lung cancer. Postcontrast standard SPACE images (A, C, and E) show multiple variable-sized, enhancing lesions in both cerebral hemispheres. Multiple enhancing lesions are also well-visualized on postcontrast wave-T1-SPACE (B, D, and F), though more noise was present than in standard SPACE.
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FIG 2.
Brain MR imaging of a 68-year-old male patient with lung cancer. Postcontrast standard SPACE (A, C, and E) shows multiple tiny enhancing lesions in both cerebral hemispheres. Although these tiny enhancing lesions are also visible on postcontrast wave-T1-SPACE (B, D, and F), they are somewhat less pronounced (arrows).
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FIG 3.
Brain MR imaging of a 54-year-old male patient with lung cancer. Postcontrast standard SPACE (A, C, and E) shows a tiny enhancing lesion (arrows) in the right frontal lobe, but it is almost invisible on postcontrast wave-T1-SPACE (B, D, and F).
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FIG 4.
Brain MR imaging of a 77-year-old male patient with colorectal cancer. Postcontrast standard (A, C, and E) and wave-T1-SPACE (B, D, and F) show multiple large-sized, enhancing masses in both cerebral hemispheres, and there was no significant difference in the visualization of enhancing lesions, though more noise was observed in postcontrast wave-T1-SPACE.

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Table 1:

Parameters of postcontrast wave-T1-SPACE and standard SPACE

	Wave-T1-SPACE	Standard SPACE
FOV (mm)	230 × 230	230 × 230
Matrix size	256 × 256	256 × 256
Section thickness (mm)	0.9	0.9
TR/TE (ms)	700/12	700/28
Flip angle	T1 variable	T1 variable
Echo-train length	60	60
Acceleration factor	4 (phase: 2; section: 2)	2 (phase: 2)
No. of slices	200	192
Scan time	2 min 2 seconds	3 min 55 seconds

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Table 2:

Comparison of lesion detectability according to the types of MR images and enhancing lesion size

	Wave-T1-SPACE	Standard SPACE	P^{^a}
No. of enhancing lesions (<5 mm) (mean)
Observer 1	1.61 (SD, 0.29)	2.84 (SD, 0.47)	<.001
Observer 2	1.41 (SD, 0.19)	2.68 (SD, 0.43)	<.001
Interobserver agreement^{^b}	0.72 (0.59–0.84)	0.81 (0.74–0.88)	<.001
No. of enhancing lesions (>5 mm) (mean)
Observer 1	1.34 (SD, 0.28)	1.32 (SD, 0.27)	.66
Observer 2	1.29 (SD, 0.27)	1.29 (SD, 0.27)	.26
Interobserver agreement^{^b}	0.95 (0.91–1.00)	1.00 (0.99–1.00)	<.001

↵a P values derived from the Wilcoxon signed-rank test.
↵b Values were calculated using κ statistics and numbers in parentheses are 95% CIs.

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Table 3:

CNR_{lesion/parenchyma}, CNR_{white matter/gray matter}, and CR_{lesion/parenchyma} and image quality of postcontrast wave-T1-SPACE and standard SPACE

	Wave-T1-SPACE	Standard SPACE	P Value^{^a}
CNR (n = 21) (mean)
Lesion/parenchyma	23.03 (SD, 3.63)	53.74 (SD, 8.15)	<.001
White matter/gray matter	2.86 (SD, 0.47)	−0.99 (SD, 0.40)	<.001
CR, lesion/parenchyma (n = 21)	63.42 (SD, 8.68)	99.75 (SD, 10.88)	<.001
Overall image quality (mean)	4.27 (SD, 0.49)	4.98 (SD, 0.13)	<.001
Grade V	16 (28.6)^{^b}	55 (98.2)^{^b}
Grade IV	39 (69.6)^{^b}	1 (0.18)^{^b}
Grade III	1 (1.78)^{^b}	0 (0)^{^b}
Grade II	0 (0)^{^b}	0 (0)^{^b}
Grade I	0 (0)^{^b}	0 (0)^{^b}