Tuberous Sclerosis

Preliminary Diagnosis: Tuberous sclerosis

I. What imaging technique is first-line for this diagnosis

• MRI with contrast

• MR spectroscopy can be performed for accurately diagnosing associated cortical tubers and subependymal nodules

II. Describe the advantages and disadvantages of this technique for diagnosis of tuberous sclerosis.

Advantages

• Often diagnostic in the appropriate clinical setting.

• Useful as a surveillance imaging technique in young children and adolescents in monitoring for development of subependymal giant cell astrocytoma (SEGA)

• Able to localize anatomically and define the extent of disease better than any other imaging modality

• Does not utilize ionizing radiation

Disadvantages

• Expensive

• Time-consuming

• Prone to motion artifact

• Unable to differentiate quiescent tubers from active tubers that are associated with a seizure focus

• MR with contrast can be used only in patients with adequate renal function (i.e., GFR >30)

III. What are the contraindications for the first-line imaging technique?

• Patients with non-MR compatible metallic hardware and certain foreign bodies

IV. What alternative imaging techniques are available?

• Contrast enhanced and non-contrast enhanced CT

• PET/SPECT nuclear medicine imaging

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of tuberous sclerosis.

Contrast enhanced and non-contrast CT

Advantages

• Able to detect enhancing subependymal nodules (SEN) characteristic in tuberous sclerosis

• Can be used to follow enlarging SEN worrisome for developing SEGA

• Can be used to detect calcified SEN and cortical/subcortical tubers to better effect than MRI

• Faster than MRI and less susceptible to motion artifact

Disadvantages

• Lacks anatomic resolution of MRI

• Not as sensitive or specific as MRI in the detection of cranial lesions associated with tuberous sclerosis

• Exposes the patient to ionizing radiation

PET/SPECT nuclear medicine imaging

Advantages

• Able to differentiate active from non-active cortical/subcortical tubers, which in turn helps surgical planning if necessary

• Able to differentiate epileptogenic foci in tuberous sclerosis

• Able to differentiate SEGA from SEN

Disadvantages

• Lacks anatomic resolution compared with both CT and MR

• Easily misses lesions under 1.5 cm in size

• Exposes the patient to ionizing radiation

VI. What are the contraindications for the alternative imaging techniques?

Contrast enhanced and non-contrast CT

• Contraindicated in pregnant patients, especially during the first two trimesters.

• CT with contrast is contraindicated in patients with end-stage renal disease who are not on dialysis.

PET/SPECT nuclear medicine imaging

• Contraindicated in pregnant patients