Characterization and therapy monitoring of head and neck carcinomas using diffusion-imaging-based intravoxel incoherent motion parameters—preliminary results

Abstract

Using the intravoxel incoherent motion (IVIM) model, diffusion-related coefficient (D) and perfusion-related parameter (f) can be measured. Here, we used IVIM imaging to characterize squamous cell carcinomas of head and neck (HNSCC) and evaluated its application in follow-up after nonsurgical organ preserving therapy. Twenty-two patients with locally advanced HNSCC (clinical stage III to IVb) were examined before treatment using eight different b values (b = 0, 50, 100, 150, 200, 250, 700, 800s/mm(2)). All patients were followed for at least 7.5months after conclusion of therapy. In 16 of these patients, follow-up MRI was available. Using the IVIM approach, f and D were extracted using a bi-exponential fit. For comparison, ADC maps were calculated. The initial values of f before therapy were located between 5.9% and 12.9% (mean: 9.4 ± 2.4%) except for two outliers (f = 17.9% and 18.2%). These two patients exclusively displayed poor initial treatment response. Overall, high initial f (13.1 ± 4.1% vs. 9.1 ± 2.4%) and ADC (1.17 ± 0.08 × 10(-3) mm(2)/s vs. 0.98 ± 0.19 × 10(-3) mm(2)/s) were associated with poor short term outcome (n = 6) after 7.5months follow-up. D values before treatment were 0.98 × 10(-3) ± 0.18mm(2)/s and ADC values were 1.03 × 10(-3) ± 0.18mm(2)/s. At follow-up, in all primary responders, D (69 ± 52%), f (65 ± 46%), and ADC (68 ± 49%) increased. Our preliminary evaluation indicates that an initial high f may predict poor prognosis in HNSCC. In responders, a significant increase of all IVIM parameters after therapy was demonstrated.