ESTRO 2024 - Abstract Book

S3828

Physics - Image acquisition and processing

ESTRO 2024

Table 1: MRI acquisition parameters for the study sequence. FA = flip angle, FoV = field of view, TE = time to echo, TR = repetition time.

Results:

5 non-patient volunteers and 20 patients with suspected HNSCC (median age 57yrs, range 36 to 76yrs, 16 men) were recruited. Study imaging took 10 minutes and was well tolerated. Volume of interest averaged T 1 times (figure 1) showed strong and consistent shortening with supplemental oxygen in the thyroid gland with median (range) ΔT 1 = - 9.1% (-13.8% to 0.4%). 15 histologically confirmed primary tumours (median volume 5.04ml range 0.54ml to 33.70ml) and 41 distinct malignant nodal masses (median volume 2.62ml, range 0.26ml to 20.56ml) were identified. Median (range) of ΔT 1 times for primary tumours were -3.5% (-6.3% to -0.5%) and -3.0% (-6.3% to 4.3%) for malignant nodes. Hypoxic fraction estimates had median (range) of 30.7% (6.5% to 78.6%) for primary tumours and 59.9% (11.6% to 89.5%) for malignant nodes (figure 2). 11/15 (73%) of patients with confirmed HNSCC proceeded to curative intent radiotherapy with 9 undergoing post treatment 19 FDG-PET scan (1 patient had post-treatment MRI scan). 70% (7/10) of these primary tumours were classed as radiotherapy responders with 30% (3/10) showing residual disease, confirmed histologically in 2 cases. Mean estimated hypoxic fractions were 37.7% (95% CI 18.0% to 57.3%) and 59.0% (95% CI 44.6% to 73.3%) for responding and non-responding primary tumours respectively (p=0.126 unequal variance t-test). VOI mean ΔT1 values were -3.5% (95% CI -5.4% to -1.6%) for responding and -3.1% (95% CI -3.9% to -2.3%) for residual disease (p=0.726 unequal variance t-test).

Figure 1: Notched box plots of volume of interest averaged changes in T1 times following commencement of supplemental oxygen delivery for 3 organs at risk and malignant tissue. Numbers in brackets indicate the number of distinct volumes contoured.