Molecular, Pathological, Clinical, and Therapeutic Aspects of Perihematomal Edema in Different Stages of Intracerebral Hemorrhage

Table 3

The merits and shortcomings of different quantitative methods of PHE after ICH.

Quantitative methods	Merits	Shortcomings	References
Preclinical studies
Brain water content	It is widely used to assess the severity of brain injury in animal ICH models.	It cannot accurately reflect PHE due to the difficulty in separating the perihematomal tissue from normal brain tissue directly.	[9, 101]
Brain swelling	It is a method most used to quantify the extent of brain edema in animals with stable volume of hematoma.	(i) It may be influenced by hematoma volume.; (ii) It cannot detect PHE directly and accurately.	[9, 34, 101]
MRI image	MRI may represent the gold standard for detecting and quantifying PHE in animals.	The access of small animals to high-field MRI is limited.	[53, 104–106]
Clinical studies
CT and MRI images	(i) CT images can be easily acquired.; (ii) MRI may represent the gold standard for detecting and quantifying PHE in humans.; (iii) Based on CT or MRI images, absolute PHE, rPHE, EED, and PHE growth rate have been developed to quantify PHE in humans.	(i) It is challenging to choose suitable thresholds to outline the rim of the PHE.; (ii) Absolute PHE, rPHE, EED, and PHE growth rate may be influenced by the quantification time point, the size, shape, and location of the hematoma.	[21, 108–115]
Other methods	Some noninvasive methods including midline shift on CT or MRI images, physical examination, and indirect estimation of ICP may also reflect brain edema after ICH.	They are not sufficient to detect or monitor brain edema and could not directly reflect PHE.	[117–119]

Abbreviations: PHE: perihematomal edema; ICH: intracerebral hemorrhage; CT: computerized axial tomography; MRI: magnetic resonance imaging; EED: edema extension distance; rPHE: relative perihematomal edema; ICP: intracranial pressure.