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AJNR - American Journal of Neuroradiology

Published ahead of print on December 13, 2007
doi: 10.3174/ajnr.A0885

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CSF Leaks: Correlation of High-Resolution CT and Multiplanar Reformations with Intraoperative Endoscopic Findings

V. La Fata^a, N. McLean^b, S.K. Wise^b, J.M. DelGaudio^b and P.A. Hudgins^a

^a Department of Radiology, Emory University School of Medicine, Atlanta, Ga
^b Department of Otolaryngology, Emory University School of Medicine, Atlanta, Ga

View larger version (65K): [in this window] [in a new window]   Fig 1. Patient 5. CT and endoscopy are concordant. Coronal (A) and oblique sagittal (B) MPR images generated from a 0.625-mm axial dataset demonstrate a 6-mm defect in a pneumatized pterygoid recess of the left sphenoid bone. There is mucosal thickening and an air-fluid level was present (other images) in the sphenoid sinus. At endoscopy, CSF was actively leaking at this site and the maximum size of the skull base defect (anteroposterior dimension), was identical to the CT measurement (6 mm).

View larger version (93K): [in this window] [in a new window]   Fig 2. Patient 4. CT underestimates defect size by 2 mm. Sagittal MPR image from 1.25-mm axial dataset demonstrates a 13-mm defect in the posterior wall of the right frontal sinus with soft tissue suggestive of encephalocele protruding through the defect. At endoscopy, this was a 15-mm defect. MR was performed preoperatively and showed no encephalocele.

View larger version (113K): [in this window] [in a new window]   Fig 3. Patient 12. Both readers missed a defect found at endoscopy. Coronal MPR image from 0.625-mm axial dataset missed a subtle defect of the right cribriform plate, measuring 3 mm endoscopically and 2 mm by imaging. Two defects were present on the right in this patient; readers detected the first, but not the second, defect. In retrospect, a small amount of soft tissue or fluid attenuation extends medially along the horizontal insertion of the middle turbinate, or olfactory recess, through the skull base defect.

View larger version (114K): [in this window] [in a new window]   Fig 4. Patient 3. CT shows a defect but no CSF leak at endoscopy. Axial image from 1.25-mm axial dataset demonstrates a 3-mm defect in the right sphenoid bone. During endoscopy, after mucosa was elevated off the defect, no egress of CSF was seen from the defect.

View larger version (61K): [in this window] [in a new window]   Fig 5. Patient 6. CT overestimated the size of the defect. Coronal (A) and sagittal (B) MPR images generated from a 0.625-mm axial dataset demonstrate a 5-mm defect in the right ethmoid roof. This patient has had a total ethmoidectomy, and the right middle turbinate has been resected at the skull base. There is mild mucosal thickening below the defect. At endoscopy, the CSF leak localized to this defect but measured only 2 mm.

View larger version (129K): [in this window] [in a new window]   Fig 6. Patients 13 (A and B) and 19 (C and D). Coronal and sagittal MPR images in A1 and A2 and B1 and B2 are generated from 0.625-mm and 1.25-mm axial datasets, respectively. Although both of these MPR images resulted in accurate measurements of the CSF leaks, a 2.0-mm defect of the left sphenoid roof in patient 13 is better appreciated than the larger, 5.0-mm defect of the left sphenoid roof in patient 19 because of the overall improved resolution of submillimeter axial collimation.