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Neuroradiology Case of the Week

Case 145

Alisa Johnson, Loris Cedeno, MD, Sudhir Kathuria, MD,
and PL Westesson MD, DDS, PhD

Clinical Presentation: Patient is a 50-year-old female with a history of liver transplant presenting with seizures.  This study was performed for the clinical suspicion of intracerebral hemorrhage .

Radiological Findings: On CT the right frontal lobe mass is hypo- to iso-intense and shows no enhancement.  Elsewhere within the brain there are features of volume loss with widening of ventricles, cortical sulci, Sylvian fissures and basal cisterns (Fig. 1).
     MRI Axial T1 images demonstrate hyperintense lesion in the right frontal lobe (Fig. 2) which enhances with contrast (Fig. 3).  T2-weighted and GRE images show heterogeneous hyperintensity with peripheral hypointense rim.  Mild surrounding edema and mass effect are noted (Figs. 4 & 5).
     Axial T1images show mild hyperintensity bilaterally in the globi pallidi representing chronic liver disease (Fig. 6). Hgb at time of imaging was 9.9.

Clinical Discussion: One of the first steps with a patient with a suspected stroke is to ascertain if it is an ischemic (80% of strokes) or hemorrhagic stroke (20% of stokes). The presence of gradual onset headache, vomiting, increased blood pressure, and decreased level of consciousness favor the diagnosis of intracerebral hemorrhage (ICH), while the abrupt onset of impaired cerebral function, headache, vomiting suggests the diagnosis of SAH. As the ICH becomes larger and causes a shift in intracranial contents the symptoms will increase. These are helpful but imperfect ways of determining if the patient has a ischemic or hemorrhagic stroke; therefore, it is essential that the patient is evaluated through noncontrast CT imaging for intracranial hemorrhage so that in the absence of an ICH, thrombolytic therapies can be considered. Thrombolytic therapies are most effective when used shortly after the onset of symptoms to restore blood flow and salvage ischemic brain parenchyma [1].
     Incidence of new stroke is approximately 160 cases per 100,000 population per year. Cerebral infarct is the third most common cause of death in the united states with a mortality rate between 15% - 35% with each episode. Intracerebral hemorrhage (ICH) is the cause of about 20% of cerebral vascular accidents. The most common causes of ICH are hypertension, trauma, bleeding diatheses, amyloid angiopathy, illicit drug use (i.e. amphetamines and cocaine), and vascular malformations. The pressure created by blood and surrounding brain edema is life-threatening; large hematomas have a high mortality and morbidity. The goal of treatment is to contain and limit the bleeding [1].

Neuroimaging Discussion: As mentioned above, CT is the first step in imaging a patient suspected to have an infarct to rule out hemorrhage. Acute hemorrhage usually appears as a hyperdense mass on CT. However, it can also appear isodense if Hgb <8-10 or if the patients has a bleeding diatheses such as hemophilia. Subacute hematoma will appear isodense for 1-6 weeks. Chronic hematoma will be hypodense.
     Once the stroke is classified as hemorrhagic, staging of the hematoma is based on T1 and T2 MRI imaging. On T1WI hyperacute (intracellular oxy-Hgb) and acute hematomas (intracellular deoxy-Hgb) are isointense. Both late and early subacute hematomas are hyperintense due to the met-Hgb. Early chronic hematomas are hyperintense due to the extracellular met-Hgb and ferritin/hemosiderin well. While late chronic hematomas become isodense as the hematoma is reduced to hemosiderin. T2WI have a somewhat different appearance than T1WI. The hyperacute hematomas appear hyperintense, while the acute stage is hypointense. The early and later subacute hematomas are hypointense and hyperintense respectively. In contrast the early and late chronic hematomas appear hyperintense and hypointense respectively. Since DWI utilizes T2 technique the findings are similar to T2WI. To summarize imaging of hematomas, CT is used initially to evaluate if the stroke is ischemic or hemorrhagic and MRI imaging is used to stage the hematoma [2].

References:

1. Nassisi, Denise, Hemorrhagic Stroke. EMedicine. Oct 2004.
2. Osborn AG. Diagnostic Imaging: Brain.1st ed. Amirsys Inc: Altona, 2004.