DNA double-strand breaks in blood lymphocytes induced by two-day Tc-MIBI myocardial perfusion scintigraphy.

OBJECTIVES

To investigate DNA double-strand breaks (DSBs) in blood lymphocytes induced by two-day Tc-MIBI myocardial perfusion scintigraphy (MPS) using y-H2AX immunofluorescence microscopy and to correlate the results with Tc activity in blood samples.

METHODS

Eleven patients who underwent two-day MPS were included. DSB blood sampling was performed before and 5min, 1h and 24h after the first and second radiotracer injections. Tc activity was measured in each blood sample. For immunofluorescence microscopy, distinct foci representing DSBs were quantified in lymphocytes after staining for the phosphorylated histone variant y-H2AX.

RESULTS

The Tc-MIBI activity measured on days one and two was similar (254±25 and 258±27 MBq; p=0.594). Compared with baseline DSB foci (0.09±0.05/cell), a significant increase was found at 5min (0.19±0.04/cell) and 1h (0.18±0.04/cell) after the first injection and at 5min and 1h after the second injection (0.21±0.03 and 0.19±0.04/cell, respectively; p=0.003 for both). At 24h after the first and second injections, the number of DSB foci had returned to baseline (0.06±0.02 and 0.12±0.05/cell, respectively). Tc activity levels in peripheral blood samples correlated well with DSB counts (r=0.451).

CONCLUSIONS

DSB counts reflect Tc-MIBI activity after injection for two-day MPS, and might allow individual monitoring of biological effects of cardiac nuclear imaging.

KEY POINTS

• Myocardial perfusion scintigraphy using Tc induces time-dependent double-strand breaks (DSBs) • γ-H2AX immunofluorescence microscopy shows DSB as an early response to radiotracer injection • Activity measurements of Tc correlate well with detected DSB • DSB foci induced by Tc return to baseline 24h after radiotracer injection.