The site of the CSF leak can be demonstrated on MRI with identification of CSF extending from the subarachnoid space into the sinonasal space with or without an associated cephalocele. Sensitivity of 56% to 94% and specificity of 57% to 100% have been reported for the identification of the site of the CSF leak [12- 14,55,58,61,63]. Given its superior soft-tissue contrast, MRI can also identify the contents of a cephalocele if present. MRI without IV contrast with inclusion of heavily T2-weighted images is typically sufficient for the evaluation of a CSF leak. However, MRI without and with IV contrast may be useful for identifying dural enhancement and distinguishing a meningoceles from sinus secretions [11]. Contrast-enhanced MR cisternogram is performed by spinal injection of intrathecal gadolinium, with thin-section T1-weighted images obtained before and after contrast injection. The postinjection images can be obtained immediately after contrast administration or at delayed intervals up to 24 hours after contrast administration. This technique allows for detection of both high-flow and slow-flow leaks and allows for simultaneous evaluation of cephaloceles that may be present. Sensitivity up to 100% has been reported for high-flow leaks and 60% to 70% for slow-flow leaks [12,65]. Studies have demonstrated contrast-enhanced MR cisternogram to have a higher sensitivity of 80% when compared with 33% to 72% of CT cisternogram [13,60]. Intrathecal administration of gadolinium contrast is not currently approved by the US Food and Drug Administration and requires off-label use consent [12]. Radiography Paranasal Sinuses There is no relevant literature to support the use of radiography in the evaluation of a sinonasal CSF leak. SPECT or SPECT/CT Paranasal Sinuses Three studies evaluating the efficacy of SPECT cisternography after the intrathecal injection of radiotracer reported a sensitivity of 94% with SPECT planar imaging and 94% to 100% for SPECT/CT fusion imaging for localization [13,66].
Sinonasal Disease. The site of the CSF leak can be demonstrated on MRI with identification of CSF extending from the subarachnoid space into the sinonasal space with or without an associated cephalocele. Sensitivity of 56% to 94% and specificity of 57% to 100% have been reported for the identification of the site of the CSF leak [12- 14,55,58,61,63]. Given its superior soft-tissue contrast, MRI can also identify the contents of a cephalocele if present. MRI without IV contrast with inclusion of heavily T2-weighted images is typically sufficient for the evaluation of a CSF leak. However, MRI without and with IV contrast may be useful for identifying dural enhancement and distinguishing a meningoceles from sinus secretions [11]. Contrast-enhanced MR cisternogram is performed by spinal injection of intrathecal gadolinium, with thin-section T1-weighted images obtained before and after contrast injection. The postinjection images can be obtained immediately after contrast administration or at delayed intervals up to 24 hours after contrast administration. This technique allows for detection of both high-flow and slow-flow leaks and allows for simultaneous evaluation of cephaloceles that may be present. Sensitivity up to 100% has been reported for high-flow leaks and 60% to 70% for slow-flow leaks [12,65]. Studies have demonstrated contrast-enhanced MR cisternogram to have a higher sensitivity of 80% when compared with 33% to 72% of CT cisternogram [13,60]. Intrathecal administration of gadolinium contrast is not currently approved by the US Food and Drug Administration and requires off-label use consent [12]. Radiography Paranasal Sinuses There is no relevant literature to support the use of radiography in the evaluation of a sinonasal CSF leak. SPECT or SPECT/CT Paranasal Sinuses Three studies evaluating the efficacy of SPECT cisternography after the intrathecal injection of radiotracer reported a sensitivity of 94% with SPECT planar imaging and 94% to 100% for SPECT/CT fusion imaging for localization [13,66].