EMmedonline

TUMOR

• Brain tumors usually appears as hypodense, poorly defined lesions on noncontrast CT scans.

• It is estimated that 70 – 80% of brain tumors will be apparent on plain scan.

• Calcification and hemorrhage associated with a tumor can cause it to have a hyperdense appearance.

• Tumors should be suspected on a noncontrast CT when significant edema is associated with an ill defined mass.

• IV Contrast material can help to define tumors. Contrast media will leak through the incompetent blood brain barrier into extracellular space surrounding the mass lesion, resulting in a contrast enhanced ring.

ABSCESS

• Brain abscess will appear as an ill-defined hypodensity on non contrast CT scan.

• Ring enhancement is seen with administration of IV contrast.

ISCHEMIA

• Non hemorrhagic infractions can be seen as early as to 2-3 hrs following insult, but most will begin to be clearly evident on the CT scan for 12 – 2 4 hrs.

• Earliest change in ischemia

  • Loss of grey white differentiation

  • Insular ribbon sign

• Lacunar infract are seen as discrete non hemorrhagic lesions over basal ganglia region secondary to hypertension.

Picture 1 : Insular Ribbon Sign.Note the loss of definition of the insular cortex on the left side, compare with normal insular cortex on the right side.  Picture 2: Note the Hyperdense MCA on the right side indicating thrombus load and note the surronding area there is loss of grey white differentiation.

Updated on 19/7/2015