BasicMRITF2-Acute Hematoma

Clinical Profile:

Patient presented with right hemiplegia and speech disturbances 

Findings:

There is evidence of a well-defined space-occupying lesion in the left temporo-occipito-parietal lobes. This lesion is predominantly isointense to brain parenchyma on the T1W images and turns hypointense on the T2W images. The periphery of this lesion is markedly hypointense on the gradient echo/rephased images (GRE). This lesion would represent an acute hematoma/bleed. Fluid signal intensity area anterior to the bleed would most likely represent serum due to clot retraction. Perilesional edema is noted with compression upon the adjacent left lateral ventricle. Prominent blood vessels are seen posterior to this lesion (vascular malformation).   

Discussion: 

Hyperacute hematoma is seen in the first few hours.
Acute hematoma is seen after several hours to several days following the ictus.

Causes of Intracerebral Hematoma :

• Traumatic.

• Hypertensive.

• Vascular Malformations.

• Aneurysm.

• Intratumoral Bleeds.

• Bleeding Diathesis.

• Hemorrhagic Infarcts (Arterial/Venous).

• Fragile Arteries - Amyloid Angiopathy or Arteritis.

  MRI Appearance :

  Hyperacute Hematoma :

  Freshly extravasated erythrocytes contain fully oxygenated hemoglobin and other components of blood.  The oxyhemoglobin is diamagnetic. It appears slightly hypointense on the short TR/TE images (T1W) and of high intensity on the long TR/TE images (T2W). In theory the hyperacute hematomas may not be distinguished from other intracranial mass lesions.  A clue to the presence of hyperacute hematoma may be a rim of marked hypointensity on the GRE images at the periphery of the lesion.

  Acute Hematoma :

The MR appearance of hematomas depends upon the pathophysiologic state of the hematoma, the technical factors used and changes  which occur over a period of time. The most important factor that determines the signal intensity of  blood is dependent upon the  magnetic properties of iron and it's breakdown products. In an acute hematoma the iron is in the form of deoxyhemoglobin as the deoxygenation of the extravasated blood occurs.  It is in the form of intracellular deoxyhemoglobin which is paramagnetic.  A cerebral hematoma causes compression of the surrounding tissue and thus reduces oxygen perfusion and therefore oxygen delivery. In the underperfused surrounding tissue lower partial pressure of oxygen promotes dissociation of oxygen from hemoglobin.  Acute hematomas which contain intracellular deoxyhemoglobin appear as isointense or minimally hypointense on short TR/TE images and markedly hypointense on long TR/TE images. For the diagnosis of an acute hematoma, Gradient Echo imaging is also useful.  At low field strength  acute hematomas  usually appear isointense with brain on the T2 Weighted images, at high field strength the hematoma appears to be of low signal intensity on the long TR/TE images.  At the early stage of hematoma formation  surrounding edema and serum which is formed due to clot retraction give a high intensity perimeter around the hemorrhage on T2 weighted sequences.

The peripheral hypointense rim on the T2W or GRE images may represent susceptibility effect at the border between a hematoma and brain or ? deposition of hemosiderin. 

MRI Features of Hemorrhagic Intracranial Tumors: (Primary and Secondary)

  Hemorrhages in intracranial malignancies (Primary and Secondary) account for approximately 10% of spontaneous intracranial hematomas. Those most prone to hemorrhages include metastasis from melanomas, choriocarcinomas, renal cell carcinoma, bronchogenic carcinoma and thyroid carcinoma. Among the primary malignancies, glioblastoma multiforme, oligodendroglioma and ependymomas are most likely to demonstrate significant hemorrhages. MR signal intensity pattern of hemorrhagic intracranial malignancies is different from benign intracerebral hematomas. Signal intensity patterns are more heterogeneous and complex as compared to non-neoplastic hematomas. They are usually in multiple concurrent stages with atypical pattern. Associated non-hemorrhagic tumor tissue and cystic changes with hemorrhagic fluid levels may be seen.  Nodular enhancement  following administration of gadolinium  DTPA may be useful in the diagnosis of a neoplastic source of hemorrhage. Vasogenic edema tends to persists longer in neoplastic than in non-neoplastic hemorrhages. 

References:

• Edelman RR, Hesselink JR, Zlatkin MB: Clinical Magnetic Resonance Imaging, Volume 1, 2nd ed. W.B. Saunders Company, 1996.
  a. Biochemical Basis of the MRI Appearance of Cerebral Hemorrhage.
  b. Spontaneous and Traumatic Hemorrhage.

 Primary Text for the Discussion submitted by: Dr. Rajiv Jaiswal, MD, Clinical Assistant.

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