Spontaneous intracerebral hematoma on diffusion-weighted images: influence of T2-shine-through and T2-blackout effects

Abstract

Background and purpose: On diffusion-weighted (DW) images, primary hematomas are initially mainly hyperintense, and then hypointense during the first few days after stroke onset. As in other brain disorders, variations in the T2 relaxation time of the hematoma influence the DW imaging signal intensity. Our aim was to evaluate the contribution of the T2 signal intensity and apparent diffusion coefficient (ADC) changes to signal intensity displayed by DW imaging through the course of hematoma.

Methods: The MR images of 33 patients with primary intracranial hemorrhage were retrospectively reviewed. Variations in T2-weighted echo planar images, DW imaging signal intensity, and apparent diffusion coefficient (ADC) ratios (core of hematoma/contralateral hemisphere) were analyzed according to the putative stages of hematoma, as seen on T1- and T2-weighted images.

Results: On both T2-weighted echo planar and DW images, the core of the hematomas was hyperintense at the hyperacute (oxyhemoglobin, n = 11) and late subacute stages (extracellular methemoglobin, n = 4), while being hypointense at the acute (deoxyhemoglobin, n = 11) and early subacute stages (extracellular methemoglobin, n = 7). There was a positive correlation between the signal intensity ratio on T2-weighted echo planar and DW images (r = 0.93, P < .05). ADC ratios were significantly decreased in the whole population and in each of the first three stages of hematoma, without any correlation between DW imaging findings and ADC changes (r = 0.09, P = .6).

Conclusion: Our results confirm that the core of hematomas is hyperintense on DW images with decreased ADC values at the earliest time point, and may thus mimic arterial stroke on DW images. T2 shine-through and T2 blackout effects contribute to the DW imaging findings of hyperintense and hypointense hematomas, respectively, while ADC values are moderately but consistently decreased during the first three stages of hematoma.

Fig 1.

Manual contouring of the hematoma. A, On the T2-weighted echo planar image (b = 0 mm²/s) on which the hematoma appears largest, the outer limit of the region of interest corresponded to the T2-hypointense ring. B, The region of interest is copied on the diffusion-weighted image (b = 1000 mm²/s). C, Mean absolute ADC values are computed in the region of interest. Mirror region of interest is placed on the contralateral hemisphere to compute the rADC.

Fig 2.

T2 shine-through (A, D) and T2 blackout effects (B, C) in intracerebral hematomas. A, Hyperacute hematoma in a 28-year-old man. The frontal lobe hematoma is isointense on a T1-weighted, hyperintense on a fluid-attenuated inversion recovery (not shown), T2-weighted, and DW image acquired with low ADC values. B, Acute hematoma in a 19-year-old woman. The right capsule–thalamic hematoma is isointense on a T1-weighted (not shown), hypointense on a T2-weighted, and hypointense on a DW image with low ADC values. C, Early subacute hematoma in a 54-year-old man. The right parietal lobe hematoma is hyperintense on a T1-weighted (not shown), hypointense on a T2-weighted, and hypointense on a DW image acquired with low ADC values. D, Late subacute hematoma in a 73-year-old man. The right temporo-occipital hematoma is hyperintense on a T1-weighted (not shown), hyperintense on a T2-weighted, and hyperintense on a DW image acquired with low ADC values.

Fig 3.

Signal intensity ratios according to the hematoma stages (mean ± SD). Throughout the course of the hematoma, the signal intensity ratio on DW (rS_DW) and on T2-weighted echo planar (rS_T2) images are positively correlated (r = 0.93, P <.05).

Fig 4.

Signal intensity ratio on DW images (rS_DW) and ADC ratio (rADC) according to the stage of intracerebral hematomas (mean ± SD). While rS_DW shows significant changes throughout the course of the hematoma, rADC values are moderately and significantly decreased throughout the course of hematoma (P < .001). No correlation is observed between rADC and rS_DW (r = 0.09, P = .6).