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MR Imaging Evaluation of Seizures¹

¹ From the Departments of Radiology (W.G.B.) and Neurology (R.B.S.), Long Beach Memorial Medical Center, 403 E Columbia St, Long Beach, CA 90806. Received January 29, 1999; revision requested March 31; revision received May 24; accepted July 13. Address reprint requests to W.G.B. (e-mail: wgbradley@pol.net).

View larger version (145K): [in a new window]   Figure 1a. New-onset seizures from an acute infarct in a 57-year-old man. (a) Transverse single-shot echo-planar diffusion MR image (b = 1,000) demonstrates focal areas of high signal intensity that represent acute ischemia and cytotoxic edema from occlusion of the right middle cerebral artery 4 hours after a seizure. The regions of interest (1, 2, 3) were drawn to measure the volume of the ischemic lesion for a quantitative stroke protocol. (b) Transverse T2-weighted spin-echo MR image (3,000/80 [repetition time msec/echo time msec]) obtained at the same level as a is essentially normal.

View larger version (162K): [in a new window]   Figure 1b. New-onset seizures from an acute infarct in a 57-year-old man. (a) Transverse single-shot echo-planar diffusion MR image (b = 1,000) demonstrates focal areas of high signal intensity that represent acute ischemia and cytotoxic edema from occlusion of the right middle cerebral artery 4 hours after a seizure. The regions of interest (1, 2, 3) were drawn to measure the volume of the ischemic lesion for a quantitative stroke protocol. (b) Transverse T2-weighted spin-echo MR image (3,000/80 [repetition time msec/echo time msec]) obtained at the same level as a is essentially normal.

View larger version (133K): [in a new window]   Figure 2a. New-onset seizures from a metastatic sarcoma in a 12-year-old boy. (a) Transverse T2-weighted spin-echo MR image (3,000/90) shows that the only definite cortical (ie, seizure-producing) focus (short arrow) is isointense to the gray matter. The intraventricular (long arrow) and subependymal (arrowhead) masses are also isointense to the gray matter, but they should not produce seizures. (b) Transverse enhanced T1-weighted spin-echo MR image (500/22) demonstrates three enhancing metastases. With this technique, the cortically based lesion (arrow) is now clearly distinguished from the gray matter. (Although the large central mass could also produce seizures by means of venous occlusion, there was no evidence of this on images of adjacent sections [not shown]).

View larger version (145K): [in a new window]   Figure 2b. New-onset seizures from a metastatic sarcoma in a 12-year-old boy. (a) Transverse T2-weighted spin-echo MR image (3,000/90) shows that the only definite cortical (ie, seizure-producing) focus (short arrow) is isointense to the gray matter. The intraventricular (long arrow) and subependymal (arrowhead) masses are also isointense to the gray matter, but they should not produce seizures. (b) Transverse enhanced T1-weighted spin-echo MR image (500/22) demonstrates three enhancing metastases. With this technique, the cortically based lesion (arrow) is now clearly distinguished from the gray matter. (Although the large central mass could also produce seizures by means of venous occlusion, there was no evidence of this on images of adjacent sections [not shown]).

View larger version (168K): [in a new window]   Figure 3. New-onset seizures from leptomeningeal carcinomatosis (carcinoma of the lung) in a 59-year-old woman. Although this transverse enhanced T1-weighted spin-echo MR image (500/20) depicts multiple enhancing lesions, only the largest lesions were seen on the nonenhanced T2-weighted images (not shown) because of the presence of vasogenic edema.

View larger version (158K): [in a new window]   Figure 4. New-onset seizures from glioblastoma multiforme in a 42-year-old man. Transverse enhanced T1-weighted spin-echo MR image (500/20) demonstrates a large enhancing mass with a nonenhancing necrotic region (arrow). (Necrosis is the distinguishing characteristic of glioblastoma.)

View larger version (163K): [in a new window]   Figure 5a. New-onset seizures from hemorrhagic metastases (breast carcinoma) in a 45-year-old woman. (a) Transverse nonenhanced T1-weighted spin-echo MR image (500/22) demonstrates a small high-signal-intensity lesion (short solid arrow), a larger high-signal-intensity lesion with a surrounding dark rim (long solid arrow), and a nearly isointense lesion with a subtle fluid level (open arrow). (b) Transverse enhanced T1-weighted spin-echo MR image (500/22) demonstrates tumor enhancement (arrow) along the superior margin of the nearly isointense lesion shown in a. (c) Transverse T2-weighted spin-echo MR image (3,000/90) shows that the two high-signal-intensity lesions in a can now be identified as extracellular methemoglobin surrounded by low-signal-intensity hemosiderin. The low-signal-intensity dependent portion of the previously isointense lesion is intracellular deoxyhemoglobin (arrowhead). Another acutely hemorrhagic lesion (containing deoxyhemoglobin) is noted in the right insular cortex (arrow). (Both T1- and T2-weighted images are required to adequately stage hemorrhage [7]).

View larger version (159K): [in a new window]   Figure 5b. New-onset seizures from hemorrhagic metastases (breast carcinoma) in a 45-year-old woman. (a) Transverse nonenhanced T1-weighted spin-echo MR image (500/22) demonstrates a small high-signal-intensity lesion (short solid arrow), a larger high-signal-intensity lesion with a surrounding dark rim (long solid arrow), and a nearly isointense lesion with a subtle fluid level (open arrow). (b) Transverse enhanced T1-weighted spin-echo MR image (500/22) demonstrates tumor enhancement (arrow) along the superior margin of the nearly isointense lesion shown in a. (c) Transverse T2-weighted spin-echo MR image (3,000/90) shows that the two high-signal-intensity lesions in a can now be identified as extracellular methemoglobin surrounded by low-signal-intensity hemosiderin. The low-signal-intensity dependent portion of the previously isointense lesion is intracellular deoxyhemoglobin (arrowhead). Another acutely hemorrhagic lesion (containing deoxyhemoglobin) is noted in the right insular cortex (arrow). (Both T1- and T2-weighted images are required to adequately stage hemorrhage [7]).

View larger version (157K): [in a new window]   Figure 5c. New-onset seizures from hemorrhagic metastases (breast carcinoma) in a 45-year-old woman. (a) Transverse nonenhanced T1-weighted spin-echo MR image (500/22) demonstrates a small high-signal-intensity lesion (short solid arrow), a larger high-signal-intensity lesion with a surrounding dark rim (long solid arrow), and a nearly isointense lesion with a subtle fluid level (open arrow). (b) Transverse enhanced T1-weighted spin-echo MR image (500/22) demonstrates tumor enhancement (arrow) along the superior margin of the nearly isointense lesion shown in a. (c) Transverse T2-weighted spin-echo MR image (3,000/90) shows that the two high-signal-intensity lesions in a can now be identified as extracellular methemoglobin surrounded by low-signal-intensity hemosiderin. The low-signal-intensity dependent portion of the previously isointense lesion is intracellular deoxyhemoglobin (arrowhead). Another acutely hemorrhagic lesion (containing deoxyhemoglobin) is noted in the right insular cortex (arrow). (Both T1- and T2-weighted images are required to adequately stage hemorrhage [7]).

View larger version (142K): [in a new window]   Figure 6. Worsening seizures due to hemorrhage from a arteriovenous malformation in a 31-year-old man. Transverse, T2-weighted spin-echo MR image (3,000/80) shows both intraparenchymal (large arrow) and intraventricular hemorrhage (small arrow). The low signal intensity of the hemorrhage on this image is consistent with acute hemorrhage (deoxyhemoglobin) 48 hours after a seizure.

View larger version (148K): [in a new window]   Figure 7a. Chronic seizures from a cavernous angioma in a 55-year-old man. (a) Transverse T2-weighted spin-echo MR image (3,000/90) demonstrates a classic mulberry lesion (arrow), that is, low-signal-intensity hemosiderin that surrounds multilobulated high-signal-intensity methemoglobin. (b) Sagittal T1-weighted spin-echo MR image (500/22) demonstrates high-signal-intensity methemoglobin (arrow).

View larger version (134K): [in a new window]   Figure 7b. Chronic seizures from a cavernous angioma in a 55-year-old man. (a) Transverse T2-weighted spin-echo MR image (3,000/90) demonstrates a classic mulberry lesion (arrow), that is, low-signal-intensity hemosiderin that surrounds multilobulated high-signal-intensity methemoglobin. (b) Sagittal T1-weighted spin-echo MR image (500/22) demonstrates high-signal-intensity methemoglobin (arrow).

View larger version (141K): [in a new window]   Figure 8. Cortical dysplasia in a 26-year-old man with chronic seizures. Transverse T2-weighted spin-echo MR image (3,000/90) shows thickened, disordered gray matter in several locations, including the left frontal lobe (arrow).

View larger version (149K): [in a new window]   Figure 9a. New-onset complex partial seizures due to mesial temporal sclerosis in a 23-year-old man. (a) Parasagittal T1-weighted spin-echo MR image (500/20) demonstrates the hippocampus (arrow). To optimally visualize the hippocampus, the superior part of the coronal sections should be angled 30° forward in the plane of the arrow. (b) Angled coronal fast FLAIR image (10,000/147/2,200 [repetition time msec/echo time msec/inversion time msec]; echo train length, eight) obtained through the interpeduncular cistern (open arrow) demonstrates an enlarged temporal horn (arrowhead) and a high-signal-intensity gliotic left hippocampus (solid arrow).

View larger version (193K): [in a new window]   Figure 9b. New-onset complex partial seizures due to mesial temporal sclerosis in a 23-year-old man. (a) Parasagittal T1-weighted spin-echo MR image (500/20) demonstrates the hippocampus (arrow). To optimally visualize the hippocampus, the superior part of the coronal sections should be angled 30° forward in the plane of the arrow. (b) Angled coronal fast FLAIR image (10,000/147/2,200 [repetition time msec/echo time msec/inversion time msec]; echo train length, eight) obtained through the interpeduncular cistern (open arrow) demonstrates an enlarged temporal horn (arrowhead) and a high-signal-intensity gliotic left hippocampus (solid arrow).

View larger version (19K): [in a new window]   Figure 10. Diagram shows the seizure evaluation algorithm.