Purpose or Case Report: To measure early (within 3 months) and late (beyond 3 months) changes in ADC of the lumbosacral vertebral marrow following chemotherapy in children with abdomino-pelvic neoplasms and interpret them in the context of ADC measurement reproducibility.
Methods & Materials: 63 subjects aged 5-17 years with an abdominal or pelvic tumour without prior or concomitant radiotherapy to the spine, and who had MR scans pre- and post-chemotherapy including diffusion-weighted images (DWI) with at least two b values were studied. This was approved as a Service Evaluation by our institution.
Patients on any other type of medication, with bony illness or artefacts on DWI were exclueded. Analysable examinations were anonymised and stored on the XNAT platform.
For this cohort the agents administered, the overall dose, and number of cycles was recorded.
DWI was correlated with morphological axial and coronal T2-W images to identify the lumbosacral vertebrae. Circular regions of interest of approximately 8-10 mm in diameter were drawn within L3, L4, L5, and S1 on a midline slice of the highest b value DWI using the in-house software Adept^®.
Data from the entire volume of interest were obtained for descriptive statistical analysis performed using GraphPad Prism software.
Additionally, median, mean, 10^th, 25^th, 75^th, and 90^th percentile ADC values were recorded. As data at baseline and at the first post-treatment time-point were normally distributed (Shapiro-Wilk test), the change between baseline and this time-point used a paired t-test.
Results: The 11 patients available for analysis were affected by hepatoblastoma (1), pancreatoblastoma (1), Wilms' tumour (4), immature ovarian teratoma with or without gliomatosis peritonei (2), ovarian dysgerminoma (1), pelvic fibromatosis (1), and pelvic desmoplastic round cell tumour (1).
At 1-3 months after completion of chemotherapy a reduction in ADC in lumbar marrow beyond measurement variability in 70% of cases was noted with a significant reduction (p=0.04), this was sustained when measured at 4-12 months post-treatment.
Only 2 cases showed an early rise in ADC, one of which then fell to below baseline values.
Conclusions: The post-chemotherapy changes in the lumbosacral marrow predominantly showed a decrease of ADC by 3 months, which was then sustained without further change beyond that time-point. The stability of the data in individual patients indicates that the findings are likely to be reliable.