The timing of ischemia onset is the key factor for selecting appropriate treatment strategies for patients [1,2].Both apparent diffusion coefficients (ADC) and T1 relaxation time in the rotating frame (T1ρ) have been employed to evaluate ischemia stages[3].Although reduced ADC has been revealed to be associated with brain ischemia, the value of ADC in staging ischemia is still controversial[4].And recent studies, in animal models, using quantitative T2 [5]or in combination with T1ρ MRI[6,7]have shown great promise in staging ischemia. However, the relationship between T1ρ values and ischemia stages in human was rarely reported. Here we exploit the characteristics of magnetic resonance imaging (MRI) with ADC and T1ρin various stages of ischemia, and expect to uncover their relationships with ischemia stages in human.73 subjects (49 males aged 29–78 years and 24 females aged 22–94years) were identified from a database of ischemic stroke patients who had been collected between March 2014 and February 2015.The ischemia stage was clinically defined according to time of ischemia. ADC (b-values of 0 and 1000 s/mm2) and T1ρ MRI experiments were performed on a Philips Achieva TX 3.0-T scanner, using an eight-channel head coil.T1ρ was performed using turbo field echo (TFE) sequence, scanning parameters were as follows: TR/TE/TI= 4800 ms/220ms/1600ms; matrix= 140×140; slice thickness= 1.8 mm; number of slices= 100; spinlock frequency= 500 Hz; spin lock time= 0, 20, 40, 60,80and 100 ms respectively. T1ρ relaxation map was generated by fitting different spin lock data with a mono-exponential decaying function, and ADC map was calculated with a mono-exponential model. Statistical significance was estimated using Student's t-test for MR parametric results between different ischemia stages. Correlation analysis was used between the parametric results and the time of ischemia. All participants were scanned successfully. The ipsilateral-contralateral differences in ∆T1ρ (ipsilateral-contralateral differences inT1ρ) ,∆ADC(ipsilateral-contralateral differences in ADC) and other values measured in stroke patients are given in Table 1. ∆T1ρ and T1ρipsi (ipsilateral T1ρ value)were elevated in the ischemic lesion from hyperacute to chronic stages; this value increased linearly as a function of time of ischemia (Figure1, Figure 2A and Figure 2B). Similar trend was not observed in the ipsilateral ADC values (ADCipsi), which seemed to be slightly lower in the early subacute stage than in the acute stage (Figure-1). The sensitivity of different MR parametric results to time of ischemia was quantified by analyzing respective correlations. For ∆T1ρ and ∆T1ρipsi with time of ischemia, the R2 values were high (0.956 and 0.941respectively,Figure-2A,2B);the ∆ADC and ADCipsi with time of ischemia had lower R2values (-0.410 and 0.550,Figure-2C,2D),The slopes of correlation between ∆T1ρ and T1ρipsi was steeper than that of ∆ADC and ADCipsi with time of ischemia, due to the excellent correspondence between T1ρ and the onset of ischemia. T1ρ and ADC both increased in the ischemic lesions with increased time from onset. Significant differences in ∆T1ρ and T1ρipsi between the acute stage and early subacute stage were observed, but not in ∆ADC and ADCipsi. Figure 3 shows representative images of at 5differents ischemia stages, respectively. Our results indicate that ∆T1ρ and T1ρipsi were elevated in the ischemiclesion, and increased over time of ischemia in a linear fashion. These measurements can provide estimates for the time of onset of ischemia in patients, especially for differential diagnosis of acute stage and early subacute stage.T1ρ MRI has the potential to be an index of ischemia in a single time point examination, with improved sensitivity over diffusion MRI (ADC) in predicting ischemic outcome.