Size-Controlled Synthesis of CoFe₂O₄ Nanoparticles Potential Contrast Agent for MRI and Investigation on Their Size-Dependent Magnetic Properties

Table 2

𝑇₁ and 𝑇₂ relaxivities (𝑟₁and 𝑟₂, resp.) measurements on CoFe₂O₄/H⁺/citrate NPs with different 𝐷_PCS, where the last two samples Feridex and Resovist are used as references.

D PCS/nm	Relaxivity at 20 MHz			Relaxivity at 60 MHz
	𝑟1 /s^−1mM^−1	𝑟2 /s^−1mM^−1	𝑟2/𝑟1	𝑟1 /s^−1mM^−1	𝑟2 /s^−1mM^−1	𝑟2/𝑟1
12.98	12.8	16.6	1.3	7.1	12.4	1.75
15.97	16.6	39.8	2.4	7.9	34.8	4.4
19.25	24.1	55.4	2.3	9.7	49.5	5.1
28.35	26.9	69.9	2.6	10	52	5.2
37.89	27.8	75.1	2.7	9.1	51	5.6
Feridex [36]	40	160	4	—	—	—
Resovist [37]	25	164	6.2	—	—	—