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• Presynaptic dopaminergic SPECT imaging is useful when the correct clinical question is being asked
  Vicky L Marshall
  Published on: 13 April 2016

• Published on: 13 April 2016

  Presynaptic dopaminergic SPECT imaging is useful when the correct clinical question is being asked

  • Vicky L Marshall, Research Fellow in Parkinson's Disease and Neurology Specialist Registrar
  • Other Contributors:
    • Donald G Grosset

  Dear Editor,

  We were very interested in the clinical experience of Eerola and colleagues in applying Beta-CIT SPECT to aid movement disorder diagnosis. However, in posing the question: “How Beta-CIT SPECT differentiates idiopathic Parkinson’s disease from other conditions” they have tested the ability of the technique to differentiate patients with Parkinson’s disease (PD) from those with Dementia with Lewy Bodies...

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  Dear Editor,

  We were very interested in the clinical experience of Eerola and colleagues in applying Beta-CIT SPECT to aid movement disorder diagnosis. However, in posing the question: “How Beta-CIT SPECT differentiates idiopathic Parkinson’s disease from other conditions” they have tested the ability of the technique to differentiate patients with Parkinson’s disease (PD) from those with Dementia with Lewy Bodies (DLB), Parkinson’s plus (P+) disorders, vascular parkinsonism, essential tremor, psychogenic parkinsonism, drug-induced parkinsonism or dystonia, and found a low specificity for the technique. Since presynaptic dopaminergic SPECT cannot accurately differentiate PD from DLB or P+ disorders, a higher specificity has been shown when the more clinically meaningful question: “Does this patient have degenerative parkinsonism or non-degenerative parkinsonism?” was asked.[1-3] The higher incidence of P+ and DLB in older patients (reflected in the mean age over 65 years exceeding that of their other diagnostic groups) compounded the issue, leading to the conclusion that the technique is less useful in older patients. Another report concludes the opposite, namely that FP-CIT SPECT dopamine transporter imaging is probably more helpful in the older patient.[4]

  As a separate point, we would welcome information regarding their gold-standard clinical diagnosis at follow-up; was the assessor blinded to clinical progression, treatment and SPECT results? Increasing congruence over time between baseline imaging and clinical diagnosis from blinded video review at up to 4 years reinforces the validity of the SPECT technique (Marek K, International Congress on Parkinson’s Disease and Related Disorders, Berlin, 2005).

  References

  1. Benamer HT, Oertel WH, Patterson J, Hadley DM, Pogarell O, Hoffken H, Gerstner A, Grosset DG. Prospective study of presynaptic dopaminergic imaging in patients with mild parkinsonism and tremor disorders: part 1. Baseline and 3-month observations. Mov Disord. 2003;18:977-84.

  2. Catafau AM, Tolosa E, DaTSCAN Clinically Uncertain Parkinsonian Syndromes Study Group. Impact of dopamine transporter SPECT using 123I- Ioflupane on diagnosis and management of patients with clinically uncertain Parkinsonian syndromes. Mov Disord. 2004;19:1175-82.

  3. Parkinson Study Group. A multicentre assessment of dopamine transporter imaging with DOPASCAN/SPECT in parkinsonism. Neurology 2000;55:1540-7.

  4. Seenan, P., MacPhee, G., Stewart, D, and Patterson, J. Retrospective analysis of the utility of FP-CIT SPECT scanning in the diagnosis of movement disorders in old age. Parkinsonism and Related Disorders 11(Supp 2), 152 [PT013-12]. 2005.

  DG has received consultancy fees from GE Healthcare

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  Conflict of Interest:
  None declared.

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