Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

Table 1 Clinical studies of intravoxel incoherent motion imaging in prostate cancer

Ref.	No. ofpatients	Pathologic reference	b-values(s/mm2)	MR parameters	PCa values1	Normal prostate values1	Significance
Döpfert et al[9]	13	TRUS biopsy	0, 50, 500, 800	3.0 T; TR/TE: 2600/66 ms; FOV: 204 mm × 204 mm; Matrix: 136 × 136; slice thickness: 3 mm; 8 averages	ADC: 1.01 ± 0.22 D: 0.84 ± 0.19 D*: 7.52 ± 4.77 f: 14.27 ± 7.10	ADC: 1.49 ± 0.17 D: 1.21 ± 0.22 D*: 6.82 ± 2.78 f: 21.25 ± 8.32	ADC, D, f significantly lower in PCa vs healthy prostate tissue Higher variation in maps of D and f compared to ADC
Shinmoto et al[10]	26	TRUS biopsy or RP	0, 10, 20, 30, 50, 80, 100, 200, 400, 1000	3.0 T; TR/TE: 5132/40 ms; Matrix: 80 × 80; slice thickness/gap: 3.5/0.1 mm; iPAT factor, 2; NEX = 2	ADC: 0.90 ± 0.16 D: 0.50 ± 0.15 D*: 5.35 ± 6.27 f: 35 ± 13	ADC: 1.76 ± 0.22 D: 0.89 ± 0.24 D*: 3.02 ± 0.86 f: 58 ± 11	ADC, D, f significantly lower in PCa vs noncancerous PZ Improved fit in 81% of study subjects for biexponential curve
Kuru et al[11]	27	MR-TRUS fusion biopsy	0, 50, 100, 150, 200, 250, 800	3.0 T; TR/TE: 3100/52 ms; FOV: 280 mm × 210 mm; Matrix: 128 × 96; slice thickness: 3 mm; iPAT factor, 2; 5 averages	ADC: 0.88 ± 0.29 D: 1.04 ± 0.23 D*: 31.1 ± 45.0 f: 9.5 ± 5.5	ADC: 1.56 ± 0.23 D: 1.44 ± 0.19 D*: 10.9 ± 4.0 f: 11.1 ± 5.0	Only D and ADC showed high AUC (≥ 0.90) for PCa vs normal Limited differentiation of PCa grade using f or D*
Pang et al[12]	33	MR-TRUS fusion biopsy	0, 188, 375, 563	3.0 T; TR/TE: 4584/59 ms; FOV:160 × 180 mm; slice thickness: 3.0 mm; iPAT factor, 2; 4+ averages	D: 0.99 ± 0.29 f: 7.2 ± 2.6 Ktrans: 0.39 ±0.22 Vp: 8.4 ± 6.6	D: 1.76 ± 0.35 f: 3.7 ± 1 .9 Ktrans: 0.18 ± 0.10 Vp: 3.4 ± 2.6	Significant increase in f for PCa vs normal prostate Pearson’s correlation coefficient (r) for f and Ktrans of 0.51

¹Values are mean ± SD [ADC: Apparent diffusion coefficient (μm²/ms); D: molecular diffusion coefficient (μm²/ms); D*: Perfusion-related diffusion coefficient (μm²/ms); f: Perfusion fraction (%); K^trans: Volume transfer constant (min^-1); V_p: Plasma fractional volume (%)]. AUC: Area under curve; FOV: Field of view; GS: Gleason score; iPAT: Integrated parallel acquisition techniques; IVIM: Intravoxel incoherent motion; MR: Magnetic resonance; NEX: Number of excitations; PCa: Prostate cancer; PZ: Peripheral zone; RP: Radical prostatectomy; T: Tesla; TE: Time of echo; TR: Time of repetition; TRUS: Transrectal ultrasound.

Table 2 Clinical studies of diffusion kurtosis imaging in prostate cancer

Ref.	No. ofpatients	Pathologic reference	b-values(s/mm2)	MR parameters	Quantitative parameters1	Significance
Quentin et al[14]	31	Biopsy	0, 300, 600, 1000	3.0 T; TR/TE: 1700/101 ms; FOV: 204 × 204 mm; Matrix: 136 × 136; slice thickness: 6 mm; iPAT factor, 2; 4 averages	Kaxial, PCa: 1.78 ± 0.39 Kaxial, TZ: 1.40 ± 0.12 Kaxial, PZ: 1.09 ± 0.12	DKI better fit than monoexponential; Difference for K between PCa and normal TZ/PZ is significant
Rosenkrantz et al[16]	47	Biopsy	0, 500, 1000, 1500, 2000	3.0 T; TR/TE: 3500/81 ms; FOV: 280 mm × 218 mm; Matrix: 100 × 100; slice thickness: 4 mm; iPAT factor, 2; 6 averages	K, high GS: 1.05 ± 0.26 K, low GS: 0.89 ± 0.20 K, PZ: 0.57 ± 0.07	Significant difference between K in high GS vs low GS sextants; K found to have better sensitivity, AUC than ADC or D for PCa
Suo et al[17]	19	RP	0, 500, 800, 1200, 1500, 2000	3.0 T; TR/TE: 3940/106 ms; FOV: 280 mm × 280 mm; Matrix: 128 × 128; slice thickness/gap: 3/1 mm; 4 averages	K, PCa: 0.96 ± 0.20 K, PZ: 0.59 ± 0.08	Significant difference for K between PCa and normal PZ; GS correlates significantly with K
Tamura et al[18]	20	RP	0, 10, 20, 30, 50, 80, 100, 200, 400, 1000, 1500	3.0 T; TR/TE: 5000/49 ms; FOV: 240 × 240 mm; Matrix: 80 × 80; slice thickness/gap: 3.5/0.1 mm; iPAT factor, 2; NEX = 2	K, PCa: 1.19 ± 0.24 K, BPH: 0.99 ± 0.28 K, PZ: 0.63 ± 0.23	Significant difference for K between PCa and normal PZ but marked overlap for K between PCa and BPH

¹Values are mean ± SD [K: Kurtosis parameter (unitless); K_axial: Axial kurtosis (unitless)]. AUC: Area under curve; BPH: Benign prostatic hyperplasia; DKI: Diffusional kurtosis imaging; FOV: Field of view; GS: Gleason score; iPAT: Integrated parallel acquisition techniques; MR: Magnetic resonance; NEX: Number of excitations; PCa: Prostate cancer; PZ: Peripheral zone; RP: Radical prostatectomy; T: Tesla; TE: Time of echo; TR: Time of repetition; TZ: Transitional zone.