Analysis of Cystic Intracranial Lesions Performed with Fluid-Attenuated Inversion Recovery MR Imaging
Italo Aprile
,a,
Francesca Iaizaa,
Antonino Lavaronia,
Riccardo Budaia,
Pierluigi Dolsoa,
Cathryn A. Scotta,
Carlo A. Beltramia and
Giuliano Fabrisa
a From the Departments of Neuroradiology (I.A., F.I., A.L., P.D., G.F.) and Neurology-Clinical Neurophysiology (R.B.), S. Maria della Misericordia General Hospital, and the Institute of Pathology (C.A.S., C.A.B.), University of Udine, Udine, Italy.
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FIG 1. Graphic representation of the probability distribution of cystic intracranial lesions being clustered around the center of two groups: free water-like and non-free water-like–filled lesions. The x axis indicates the distance of each case from the center of each of the two groups. The y axis represents the contrast resolution between CSF and cystic intracranial lesion content. The z axis represents the probability of being clustered in one of the two groups. As the distance from the center of one of the two clusters increases, the probability coefficient decreases.
A, Calculated on T1-weighted images (R-T1).
B, Calculated on T2-weighted images (R-T2).
C, Calculated on PD-weighted images (R-PD).
D, Calculated on FLAIR images (R-FLAIR).
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FIG 2. Distribution of the ratio in signal intensity difference between content of cystic inracranial lesions and CSF using the Box-Jenkins method on the two groups of lesions: free water-like and non-free water-like.
A, PD-weighted sequences.
B, FLAIR sequences.
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FIG 3. Left temporal glioblastoma.
A, T1-weighted sequence. The tumor has a central part (arrow) with a dyshomogeneous but mostly hyperintense signal in comparison with cysternal and ventricular CSF.
B, T2-weighted image. The solid part of the tumor (arrowhead) is hypointense, and the necrotic part (arrow) and perilesional edema are hyperintense, similar to CSF. The region of interest was taken from the central, necrotic part (arrow) in all the images.
C, PD-weighted image. Necrosis (arrow) is easily distinguished from the solid neoplastic tissue (arrowhead) but with less resolution than that achieved using the T2-weighted image. The necrotic area appears slightly hyperintense in comparison with CSF.
D, FLAIR sequence. Both the necrotic tissue (arrow) and perilesional edema remain hyperintense. The tumor tissue (arrowhead) remains hypointense and the necrotic material (arrow) is highly hyperintense, whereas CSF has a low signal.
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FIG. 4. Right frontal recurrence of an oligodendroglioma. The difference in signal intensity between CSF and cystic content is probably attributable to protein debris, typical of neoplastic lesions. This feature is evident on all sequences but is more obvious with the FLAIR sequence. With this pulse sequence, both the neoplastic tissue and peritumoral edema are appreciated more easily considering the saturation of the CSF signal in the sulci.
A, T1-weighted image. The cystic content (arrow) is slightly hyperintense in comparison with CSF (in the cortical sulci).
B, T2-weighted image. The neoplastic cystic content (arrow) has an elevated signal intensity in comparison with CSF.
C, PD-weighted image. The cystic content signal intensity is slightly hyperintense (arrow) in comparison with CSF.
D, FLAIR pulse sequence. The cystic content (arrow) shows an elevated signal intensity.
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FIG 5. Right temporal arachnoid cyst. The cyst's content (arrow) is isointense to CSF (see controlateral cortical cysterns, fourth ventricle, lateral ventricles) in all of the sequences. This appearance is attributable to the similarity of CSF and cystic content.
A, T1-weighted sequence.
B, T2-weighted sequence.
C, PD-weighted sequence.
D, FLAIR sequence. On the FLAIR image, the hyperintensity seen in the fourth ventricle is owing to flow artifact.
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FIG 6. Left temporal choroidal fissure cyst. The cystic content (arrow) is very similar to CSF, and, for this reason, its signal intensity is equivalent to CSF (see interpedunclar and other cisterns) in all of the sequences.
A, T1-weighted sequence.
B, T2-weighted sequence.
C, PD-weighted sequence. On the PD-weighted image, the lesion is not clearly evident because its content is isointense to the temporal cortex.
D, FLAIR sequence.
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FIG 7. Right pontocerebellar cistern epidermoid cyst.
A, T1-weighted image. The cystic content (arrow) is slightly hyperintense to CSF (see compressed fourth ventricle).
B, T2-weighted image. The cystic content (arrow) is isointense to CSF. The T2-weighted image also shows a right temporal gliotic area (arrowhead).
C, PD-weighted sequence. The cystic content (arrow) is slightly hyperintense to CSF.
D, FLAIR sequence. The cystic content (arrow) is markedly hyperintense when compared with CSF. In this case, the content of the cyst was not saturated from using FLAIR and the lesion was misclassified as non-free water<<014>>like. The FLAIR image also shows a right temporal gliotic area (arrowhead).
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