Dual-energy CT based monitoring of treatment-induced bone marrow changes in lung cancer patients: preliminary results.

Abstract

Systemic lung cancer treatment-induced changes in bone marrow attenuation assessed via dual-energy CT-based virtual non-calcium (VNCa) imaging of the axial skeleton and their relationship to hematological laboratory have not yet been investigated. VNCa bone marrow images of the axial skeleton derived from 93 unenhanced reduced dose dual-energy CTs of the thorax and abdomen of 31 patients were retrospectively analyzed. Each patient had received one pre-therapy baseline exam and two consecutive follow-up exams (FU1 and FU2) at a mean of 7.7 and 11.7 weeks after start of therapy. Concurrent hematologic laboratory data were available for every exam. Seven regions of interest were placed in the spine and pelvis and mean VNCa bone marrow attenuation was measured. Twenty-two Patients receiving highly myelotoxic treatment (Group A) were compared to 9 patients receiving less toxic substances (Group B). Median bone marrow attenuation in Group A/Group B was -31.8 HU (IQR 12.7)/40.6 HU (IQR, 12.2) at baseline, -46.5 HU (IQR, 12.5)/-43.8 HU (15.7) at FU1 and -46.9 HU (IQR, 22.0)/-38.5 HU (IQR, 18.5) at FU2. In both subgroups the reduction of the mean attenuation between baseline and FU1 was statistically significant although in Group A it was more pronounced; no significant difference was found between FU1 and FU2. The differences between Groups were not statistically significant. Leukopenia rates at FU1 and FU 2 were 50% and 54.5% in Group A and 0% and 22% in Group B. Anemia rates rose from 31.8% at baseline to 90% at FU1 and 86.4% at FU2 in Group A and fell from 77.8% at baseline to 66.7% at FU1 and further to 55.6% at FU2 in Group B. Both highly myelotoxic as well as-to a smaller degree-less myelotoxic systemic therapy led to a significant drop in bone marrow attenuation with no significant tendency towards subsequent elevation irrespective of the treatment's degree of toxicity or the presence of myelosuppression and not even under hematological supportive therapy. The results suggest that in this clinical setting an increase in bone marrow attenuation should be regarded as suspicious for tumor infiltration.