Assessment of digital ischaemia and evaluation of response to therapy by 99mTc sestamibi limb scintigraphy after local cooling of the hands in patients with vasospastic Raynaud's syndrome.

Aim: Cold induced arteriolar constriction in patients with vasospastic Raynaud's syndrome (VRS) produces temporary digital ischaemia. The aim of this study was to ascertain whether 99mTc sestamibi scintigraphy is useful in the diagnosis and the monitoring of treatment in VRS.

Methods: Fifteen patients with VRS and 20 matched normal controls underwent examination. Twelve patients with VRS received therapy. For each patient, one hand was immersed in iced water for 30s while the other hand served as a control. Ten minutes after cooling, 99mTc sestamibi was injected and imaging was performed 60min later. The per cent decrease of the perfusion (%DP) was calculated by semiquantitative analysis to determine the severity of hypoperfusion.

Results: In all patients with VRS, moderate or marked hypoperfusion were seen in 99mTc sestamibi images after exposure to the iced water, while there was minimal or mild hypoperfusion in the control groups. Values for %DP were 46.86 +/- 19.04 and 7.85 +/- 4.53 for the VRS group and normal subjects, respectively. The difference between both groups was statistically significant (P = 0.0000). In 12 treated patients with VRS, pre-treatment and post-treatment %DP values were 51.16 +/- 18.42 and 33.58 +/- 17.83, respectively, and a significant difference was seen between both values (P = 0.001). However, there was still a statistically significant difference between control subjects and post-therapy values (7.85 +/- 4.53 vs. 33.58 +/- 17.83, P = 0.0000). The +/- 95% confidence interval of DP for control subjects was 5.7-10% (chi-squared, P = 0.000). When a DP of 10% was used as a cut-off point, sensitivity, specificity and diagnostic accuracy were 100%, 70% and 83%, respectively, for the 99mTc sestamibi scan. There was also a strong correlation between %DP and the duration of the disease (r = 0.80, P = 0.0003).

Conclusion: The results of this study indicate that a 99mTc sestamibi scan is a valuable imaging method for the determination of digital ischaemia in vasospastic Raynaud's syndrome, and may play a role in evaluating the response to therapy.