The cardiac I-123 MIBG (metaiodobenzylguanidine) scan is a nuclear medicine imaging test that assesses sympathetic cardiac innervation. MIBG is a norepinephrine analog that is taken up by sympathetic nerve endings via the norepinephrine transporter. In neurodegenerative diseases, loss of sympathetic innervation produces characteristic patterns that help differentiate between tauopathies and synucleinopathies[1].
| Pattern | Disease | H/M Ratio | Interpretation |
|---|---|---|---|
| Reduced | Parkinson's disease | <1.6 | Sympathetic denervation — synucleinopathy |
| Reduced | Dementia with Lewy bodies | <1.6 | Sympathetic denervation — synucleinopathy |
| Reduced | Multiple system atrophy | <1.6 | Sympathetic denervation — synucleinopathy |
| Normal | Corticobasal syndrome | >1.8 | Intact sympathetic — tauopathy |
| Normal | Progressive supranuclear palsy | >1.8 | Intact sympathetic — tauopathy |
| Normal | Alzheimer's disease | >1.8 | Intact sympathetic |
| Parameter | Normal | Abnormal |
|---|---|---|
| Early H/M ratio | >1.8 | <1.6 |
| Delayed H/M ratio | >1.8 | <1.6 |
| Washout rate | <10%/hr | May be elevated |
Given this patient's:
Cardiac MIBG scan would be expected to show:
This test can help determine if there is mixed pathology (tau + synuclein) if uptake is borderline.
| Component | Cost (USD) |
|---|---|
| Procedure | $1,500-2,500 |
| Insurance | Often requires pre-authorization |
| Availability | University hospitals with nuclear medicine |
Cardiac MIBG scintigraphy provides unique information about post-ganglionic sympathetic neurons that complements other autonomic assessments. Each test evaluates different components of the autonomic nervous system[2].
| Test | Target | What It Measures | MIBG Advantage |
|---|---|---|---|
| Cardiac MIBG | Post-ganglionic sympathetic | Cardiac sympathetic innervation | Direct visualization of sympathetic nerve terminals |
| HRV Analysis | Parasympathetic + sympathetic | Heart rate variability | Non-invasive, no radiation |
| Orthostatic Hypotension | Central autonomic | BP response to standing | Identifies neurogenic OH severity |
| QSART/TST | Post-ganglionic sudomotor | Sweat response | Evaluates peripheral autonomic fibers |
| Urodynamic Studies | Pelvic autonomic | Bladder function | Direct assessment of detrusor function |
MIBG is particularly valuable when:
Consider other tests when:
| Center | Location | Notes |
|---|---|---|
| Mayo Clinic | Rochester, MN; Phoenix, AZ; Jacksonville, FL | Leading center for movement disorders, offers MIBG |
| Massachusetts General Hospital | Boston, MA | Autonomic disorders program |
| University of Pennsylvania | Philadelphia, PA | Parkinson's disease center |
| Cleveland Clinic | Cleveland, OH | Movement disorders program |
| UCLA Medical Center | Los Angeles, CA | Lewy body dementia program |
| Mount Sinai | New York, NY | Autonomic testing available |
| Johns Hopkins | Baltimore, MD | Movement disorders center |
| Center | Location | Notes |
|---|---|---|
| Royal Free Hospital | London, UK | Autonomic unit |
| University College London | London, UK | PSP Research Centre |
| Karolinska Institutet | Stockholm, Sweden | Movement disorders |
| Tokyo Metropolitan Institute | Tokyo, Japan | High-volume center |
| Università di Bologna | Italy | Autonomic research |
| University of Tübingen | Germany | Movement disorders |
Goldstein DS, et al. Cardiac sympathetic denervation in Parkinson disease. Ann Intern Med. 2000. ↩︎
Treister R, et al. Autonomic function testing in neurodegenerative diseases. J Neurol Sci. 2023. ↩︎