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. 2023 Jul 1;44(7):613-621.
doi: 10.1097/MNM.0000000000001703. Epub 2023 May 3.

Baseline and early digital [ 18 F]FDG PET/CT and multiparametric MRI contain promising features to predict response to neoadjuvant therapy in locally advanced rectal cancer patients: a pilot study

Floris A Vuijk  1 , Shirin Feshtali Shahbazi  2 , Wyanne A Noortman  3   4 , Floris H P van Velden  3 , Petra Dibbets-Schneider  3 , Andreas W K S Marinelli  5 , Peter A Neijenhuis  6 , Roderick Schmitz  7 , Eidrees Ghariq  2 , Laura A Velema  8 , Femke P Peters  8   9 , Frits Smit  3 , Koen C M J Peeters  1 , Sofieke J D Temmink  1 , Stijn A L P Crobach  10 , Hein Putter  11 , Alexander L Vahrmeijer  1 , Denise E Hilling  1   12   13 , Lioe-Fee de Geus-Oei  3   4   14
Affiliations

Baseline and early digital [ 18 F]FDG PET/CT and multiparametric MRI contain promising features to predict response to neoadjuvant therapy in locally advanced rectal cancer patients: a pilot study

Floris A Vuijk et al. Nucl Med Commun. .

Abstract

Objective: In this pilot study, we investigated the feasibility of response prediction using digital [ 18 F]FDG PET/computed tomography (CT) and multiparametric MRI before, during, and after neoadjuvant chemoradiation therapy in locally advanced rectal cancer (LARC) patients and aimed to select the most promising imaging modalities and timepoints for further investigation in a larger trial.

Methods: Rectal cancer patients scheduled to undergo neoadjuvant chemoradiation therapy were prospectively included in this trial, and underwent multiparametric MRI and [ 18 F]FDG PET/CT before, 2 weeks into, and 6-8 weeks after chemoradiation therapy. Two groups were created based on pathological tumor regression grade, that is, good responders (TRG1-2) and poor responders (TRG3-5). Using binary logistic regression analysis with a cutoff value of P ≤ 0.2, promising predictive features for response were selected.

Results: Nineteen patients were included. Of these, 5 were good responders, and 14 were poor responders. Patient characteristics of these groups were similar at baseline. Fifty-seven features were extracted, of which 13 were found to be promising predictors of response. Baseline [T2: volume, diffusion-weighted imaging (DWI): apparent diffusion coefficient (ADC) mean, DWI: difference entropy], early response (T2: volume change, DWI: ADC mean change) and end-of-treatment presurgical evaluation MRI (T2: gray level nonuniformity, DWI: inverse difference normalized, DWI: gray level nonuniformity normalized), as well as baseline (metabolic tumor volume, total lesion glycolysis) and early response PET/CT (Δ maximum standardized uptake value, Δ peak standardized uptake value corrected for lean body mass), were promising features.

Conclusion: Both multiparametric MRI and [ 18 F]FDG PET/CT contain promising imaging features to predict response to neoadjuvant chemoradiotherapy in LARC patients. A future larger trial should investigate baseline, early response, and end-of-treatment presurgical evaluation MRI and baseline and early response PET/CT.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Fig. 1
Fig. 1
Forrest plot of investigated features. Figure shows odds ratio for TRG1-2 with 95% confidence intervals from binary logistical regression analyses on logarithmic scale (x-axis). ADC mean, mean apparent diffusion coefficient; DWI entropy, tumor entropy on diffusion-weighted imaging series; DWI volume, tumor volume on diffusion-weighted imaging series; MTV, metabolic tumor volume; SULpeak, peak standardized uptake value corrected for lean body mass; SUVmax, maximum standardized uptake value; T2 entropy, tumor entropy on T2 series; T2 volume, tumor volume on T2 series; TLG, total lesion glycolysis.
Fig. 2
Fig. 2
[18F]FDG PET/CT and T2 weighted MRI images of a poor responder before, during, and after neoadjuvant chemoradiotherapy. A fifty-eight-year-old woman with cT4aN2M0 rectal cancer had a partial response to chemoradiotherapy to a yiT3N1M0. Pathological examination showed a ypT3N0M0 tumor and pTRG of 4. SUVmax was 17.8 at baseline, 17.8 at interim assessment, and 6.5 at reevaluation. Figure shows [18F]FDG PET/CT fusion (a–c) and PET-only (d–f) images as well as T2 weighted MRI (g–i) images before (a, d, g), during (b, e, h) and after (c, f, i) neoadjuvant chemoradiotherapy. CT, computed tomography; pTRG, pathological tumor regression grade; SUVmax, maximum standardized uptake value.
Fig. 3
Fig. 3
[18F]FDG PET/CT and T2 weighted MRI images before, during, and after neoadjuvant therapy of a patient with clinical complete response. A sixty-two-year-old man with cT4bN2M0 rectal cancer had a good response to a yiT1-2N0M0 which further regressed to a yiT0N0M0 6 months after chemoradiotherapy, and is currently still followed in the watch-and-wait after 12 months of recurrence-free follow-up. SUVmax was 18.1 at baseline, 10.4 at interim assessment, and too low to measure at reevaluation. Figure shows [18F]FDG PET/CT fusion (a–c) and PET-only (d–f) images as well as T2 weighted MRI (g–i) images before (a, d, g), during (b, e, h) and after (c, f, i) neoadjuvant chemoradiotherapy. CT, computed tomography; SUVmax, maximum standardized uptake value.
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