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. 2020 Apr 16;20(1):326.
doi: 10.1186/s12885-020-06836-y.

Treatment-related changes in neuroendocrine tumors as assessed by textural features derived from 68Ga-DOTATOC PET/MRI with simultaneous acquisition of apparent diffusion coefficient

Manuel Weber  1 , Lukas Kessler  2 , Benedikt Schaarschmidt  3 , Wolfgang Peter Fendler  2 , Harald Lahner  4 , Gerald Antoch  5 , Lale Umutlu  3 , Ken Herrmann  2 , Christoph Rischpler  2
Affiliations

Treatment-related changes in neuroendocrine tumors as assessed by textural features derived from 68Ga-DOTATOC PET/MRI with simultaneous acquisition of apparent diffusion coefficient

Manuel Weber et al. BMC Cancer. .

Abstract

Background: Neuroendocrine tumors (NETs) frequently overexpress somatostatin receptors (SSTRs), which is the molecular basis for 68Ga-DOTATOC positron-emission tomography (PET) and radiopeptide therapy (PRRT). However, SSTR expression fluctuates and can be subject to treatment-related changes. The aim of this retrospective study was to assess, which changes in PET and apparent diffusion coefficient (ADC) occur for different treatments and if pre-therapeutic 68Ga-DOTATOC-PET/MRI was able to predict treatment response to PRRT.

Methods: Patients with histopathologically confirmed NET, at least one liver metastasis > 1 cm and at least two 68Ga-DOTATOC-PET/MRI including ADC maps were eligible. 68Ga-DOTATOC-PET/MRI of up to 5 liver lesions per patients was subsequently analyzed. Extracted features comprise conventional PET parameters, such as maximum and mean standardized uptake value (SUVmax and SUVmean) and ADC values. Furthermore, textural features (TFs) from both modalities were extracted. In patients with multiple 68Ga-DOTATOC-PET/MRI a pair of 2 scans each was analyzed separately and the parameter changes between both scans calculated. The same image analysis was performed in patients with 68Ga-DOTATOC-PET/MRI before PRRT. Differences in PET and ADC maps parameters between PRRT-responders and non-responders were compared using Mann-Whitney test to test differences among groups for statistical significance.

Results: 29 pairs of 68Ga-DOTATOC-PET/MRI scans of 18 patients were eligible for the assessment of treatment-related changes. In 12 cases patients were treated with somatostatin analogues between scans, in 9 cases with PRRT and in 2 cases each patients received local treatment, chemotherapy and sunitinib. Treatment responders showed a statistically significant decrease in lesion volume and a borderline significant decrease in entropy on ADC maps when compared to non-responders. Patients treated with standalone SSA showed a borderline significant decrease in mean and maximum ADC, compared to patients treated with PRRT. No parameters were able to predict treatment response to PRRT on pre-therapeutic 68Ga-DOTATOC-PET/MRI.

Conclusions: Patients responding to current treatment showed a statistically significant decrease in lesion volume on ADC maps and a borderline significant decrease in entropy. No statistically significant changes in PET parameters were observed. No PET or ADC maps parameters predicted treatment response to PRRT. However, the sample size of this preliminary study is small and further research needed.

Keywords: DOTATOC; NET; PET/MRI; Radiomics; Radiopeptide therapy; Textural features.

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Conflict of interest statement

Wolfgang P. Fendler and Ken Herrmann are Editorial Board Member of BMC Cancer.

Figures

Fig. 1
Fig. 1
Boxplots and charts displaying changes in DOTATOC-PET parameters, when comparing patients showing treatment response to their current treatment with patients with disease progression
Fig. 2
Fig. 2
Boxplots and charts displaying changes DOTATOC-PET parameters, when comparing patients undergoing SSA vs. patients undergoing PRRT
Fig. 3
Fig. 3
Boxplots and charts showing changes in ADC map, when comparing patients showing treatment response to their current treatment with patients with disease progression
Fig. 4
Fig. 4
Boxplots and charts displaying changes in ADC map, when comparing patients undergoing SSA vs. patients undergoing PRRT
Fig. 5
Fig. 5
Boxplots and charts showing the differences in pre-PRRT SSTR expression as assessed by 68Ga-DOTATOC-PET/MRI between patients who would later respond to treatment and patients who would not. SUVmean, mean standardized uptake value; SUVstd, standard deviation of standardized uptake value; SUV max, maximum standardized uptake value; cov, coefficient of variance; TLRE, total lesion receptor expression\
Fig. 6
Fig. 6
Boxplots and charts showing the differences in pre-PRRT ADC maps between patients who would later respond to treatment and patients who would not. ADCmean, mean apparent diffusion coefficient; ADCstd, standard deviation of apparent diffusion coefficient; ADCmax, maximum apparent diffusion coefficient; COV, coefficient of variance; TLADC, total lesion apparent diffusion coefficient
See this image and copyright information in PMC

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