In vivo imaging of apoptosis by 99mTc-Annexin V scintigraphy: visual analysis in relation to treatment response

Background and purpose: Anticancer therapy induces apoptosis in a dose- and time-dependent fashion. 99mTc-Hynic-rh-Annexin V scintigraphy (TAVS) enables non-invasive in vivo imaging of treatment-induced apoptosis. We identified the visual patterns of 99mTc-Hynic-rh-Annexin V tumour uptake and related these to treatment response. Patients and methods: Thirty-three patients with malignant lymphoma, leukaemia, NSCLC , H and NSCC, scheduled for radiotherapy, platinum-based chemotherapy or concurrent chemoradiation , underwent TAVS before and early after the start of treatment. Planar and SPECT images were visually examined to assess changes in tumour 99mTc-Hynic-rh-Annexin V uptake. Twenty-nine patients were eligible for further analysis. Annexin V uptake before (Ubaseline) and early after (Upost) the start of treatment was graded using a four-step scale: 0, absent; 1, weak; 2, moderate and 3, intense. The difference between these values (ΔU) was calculated and correlated to tumour response after therapy (Spearman rank correlation test). Results: Weak to moderate Ubaseline was detected in 13/15 patients with a complete response and Upost was markedly increased in all these cases. Partial response was associated with weak to moderate Ubaseline and a moderately increased Upost (ΔU range 1-2). In patients with stable disease, Ubaseline was predominantly weak, without considerable changes in uptake after the start of treatment (ΔU range 0-1). Finally, in case of progressive disease , either no tumour uptake or a decrease in Upost was detected . A statistically significant correlation was found between changes in 99mTc-Hynic-rh-Annexin V tumour uptake and clinical response Conclusions: Complete or partial tumour response was associated with a marked increase of 99mTc Hynic-rh-Annexin V accumulation early during treatment compared to baseline values. In case of stable or progressive disease, pretreatment scans demonstrated predominantly low 99mTc Hynic-rh-Annexin V tumour uptake and no significant increase early after treatment. These results indicate that TAVS might be useful as a predictive test for treatment response