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.

  • Often diagnostic in the appropriate clinical setting.

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  • 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

  • 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
  • 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

  • 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
  • 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

  • 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