Investig Magn Reson Imaging.  2015 Jun;19(2):107-113. 10.13104/imri.2015.19.2.107.

Findings Regarding an Intracranial Hemorrhage on the Phase Image of a Susceptibility-Weighted Image (SWI), According to the Stage, Location, and Size

• Lee YJ
• Lee S
• Jang J
• Choi HS
• Jung SL
• Ahn KJ
• Kim BS
• Lee KH

• KMID: 2175590
• DOI: http://doi.org/10.13104/imri.2015.19.2.107

Abstract

PURPOSE
Susceptibility weighted imaging (SWI) is a new magnetic resonance technique that can exploit the magnetic susceptibility differences of various tissues. Intracranial hemorrhage (ICH) looks a dark blooming on the magnitude images of SWI. However, the pattern of ICH on phase images is not well known. The purpose of this study is to characterize hemorrhagic lesions on the phase images of SWI.
MATERIALS AND METHODS
We retrospectively enrolled patients with ICH, who underwent both SWI and precontrast CT, between 2012 and 2013 (n = 95). An SWI was taken, using the 3-tesla system. A phase map was generated after post-processing. Cases with an intracranial hemorrhage were reviewed by an experienced neuroradiologist and a trainee radiologist, with 10 years and 3 years of experience, respectively. The types and stages of the hemorrhages were determined in correlation with the precontrast CT, the T1- and T2-weighted images, and the FLAIR images. The size of the hemorrhage was measured by a one-directional axis on a magnitude image of SWI. The phase values of the ICH were qualitatively evaluated: hypo-, iso-, and hyper-intensity. We summarized the imaging features of the intracranial hemorrhage on the phase map of the SWI.
RESULTS
Four types of hemorrhage are observed: subdural and epidural; subarachnoid; parenchymal hemorrhage; and microbleed. The stages of the ICH were classified into 4 groups: acute (n = 34); early subacute (n = 11); late subacute (n = 15); chronic (n = 8); stage-unknown microbleeds (n = 27). The acute and early subacute hemorrhage showed heterogeneous mixed hyper-, iso-, and hypo-signal intensity; the late subacute hemorrhage showed homogeneous hyper-intensity, and the chronic hemorrhage showed a shrunken iso-signal intensity with the hyper-signal rim. All acute subarachnoid hemorrhages showed a homogeneous hyper-signal intensity. All parenchymal hemorrhages (> 3 mm) showed a dipole artifact on the phase images; however, microbleeds of less than 3 mm showed no dipole artifact. Larger hematomas showed a heterogeneous mixture of hyper-, iso-, and hypo-signal intensities.
CONCLUSION
The pattern of the phase value of the SWI showed difference, according to the type, stage, and size.

Keyword

Intracranial hemorrhage; Phase map; Susceptibility weighted imaging; Magnetic resonance imaging

MeSH Terms

Artifacts
Axis, Cervical Vertebra
Hematoma
Hemorrhage
Humans
Intracranial Hemorrhages*
Magnetic Resonance Imaging
Retrospective Studies
Subarachnoid Hemorrhage

Figure

• 

  Fig. 1 A case of acute to early subacute subdural hemorrhage. The crescent subdural hemorrhage, along the right cerebral convexity, is shown by a pre-contrast CT (a), a T1-weighted image (b), a T2-weighted image (c), and a phase image (d). The subdural hemorrhage appears gradated and hyperdense on a pre-contrast CT (a), isointense on T1-weighted image (b), gradated hypointense on T2-weighted image (c), and heterogeneously hyper-, iso-, and hypo-signal intensities on phase a b image (d).

• 

  Fig. 2 A case of late subacute subdural hemorrhage (arrows). The crescent subdural hemorrhages, along both anterior cerebral convexities, appears hypodense on the pre-contrast CT (a) , hyperintense on T1-weighted image (b) , hyperintense on T2-weighted image (c), and homogeneous iso- to hyperintense on phase image (d).

• 

  Fig. 3 A case of acute subarachnoid hemorrhage (arrows). High density in the right parietal sulci on the pre-contrast CT (a), not definitely delineated on T1- and T2-weighted images (b, c), and homogeneous hyper-signal intensity on phase image (d).

• 

  Fig. 4 Parenchymal hemorrhage, according to size, on the phase image. A 2 mm microbleed in the left temporal lobe (arrow) showing a homogeneous hyperintense dot without a dipole artifact (a). A 4 mm microbleed in the left temporal lobe (arrow), showing a homogeneous hypointense dot surrounded by a hyperintense rim at the mid-slice of the lesion (b).

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