Treatment Assessment of pNET and NELM after Everolimus by Quantitative MRI Parameters
Maria Ingenerf1, Sophia Kiesl1, Michael Winkelmann1
1Department of Radiology, University Hospital, LMU Munich, 81377 Munich, Germany.
Abstract:
Assessment of treatment response to targeted therapies such as everolimus is difficult, especially in slow-growing tumors such as NETs. In this retrospective study, 17 patients with pancreatic neuroendocrine tumors (pNETs) and hepatic metastases (NELMs) (42 target lesions) who received everolimus were analyzed. Intralesional signal intensities (SI) of non-contrast T1w, T2w and DCE imaging, and apparent diffusion coefficients (ADCmean and ADCmin) of DWI, were measured on baseline and first follow-up MRI after everolimus initiation. Response assessment was categorized according to progression-free survival (PFS), with responders (R) showing a PFS of ≥11 months. ADCmin of NELMs decreased in Rs whereas it increased in non-responders (NR). Percentual changes of ADCmin and ADCmean differed significantly between response groups (p < 0.03). By contrast, ADC of the pNETs tended to increase in Rs, while there was no change in NRs. Tumor-to-liver (T/L) ratio of T1 SI of NELMs increased in Rs and decreased in NRs, and percentual changes differed significantly between response groups (p < 0.02). T1 SI of the pNETs tended to decrease in Rs and increase in Ns. The quotient of pretherapeutic and posttherapeutic ADCmin values (DADCmin) and length of everolimus treatment showed significant association with PFS in univariable Cox analysis. In conclusion, quantitative MRI, especially DWI, seems to allow treatment assessment of pNETs with NELMs under everolimus. Interestingly, the responding NELMs showed decreasing ADC values, and there might be an opposite effect on ADC and T1 SI between NELMs and pNETs.
Insights
Quantitative MRI, particularly diffusion-weighted imaging (DWI), can assess treatment response in pancreatic neuroendocrine tumors (pNETs) and liver metastases (NELMs) receiving everolimus. Responding tumors showed decreased apparent diffusion coefficients (ADC).
Area of Science:
- Oncology
- Radiology
- Medical Imaging
Background:
- Assessing treatment response to targeted therapies like everolimus in slow-growing neuroendocrine tumors (NETs) is challenging.
- Pancreatic neuroendocrine tumors (pNETs) with hepatic metastases (NELMs) often require effective monitoring of therapy efficacy.
Purpose of the Study:
- To evaluate the utility of quantitative magnetic resonance imaging (MRI) parameters for assessing treatment response to everolimus in patients with pNETs and NELMs.
- To correlate MRI findings with progression-free survival (PFS) to determine early indicators of treatment efficacy.
Main Methods:
- Retrospective analysis of 17 patients with pNETs and NELMs treated with everolimus.
- Baseline and follow-up MRI included non-contrast T1w, T2w, dynamic contrast-enhanced (DCE) imaging, and diffusion-weighted imaging (DWI).
- Apparent diffusion coefficients (ADCmean, ADCmin) and signal intensities (SI) were measured; response was defined by PFS (≥11 months for responders).
Main Results:
- Decreased ADCmin in NELMs was observed in responders (R), while it increased in non-responders (NR); significant differences in ADC changes between groups (p < 0.03).
- Tumor-to-liver (T/L) ratio of T1 SI in NELMs increased in R and decreased in NR, with significant differences (p < 0.02).
- The quotient of pre- and post-therapeutic ADCmin (DADCmin) and treatment duration were associated with PFS.
Conclusions:
- Quantitative MRI, especially DWI, shows promise for early treatment assessment of pNETs with NELMs under everolimus therapy.
- Responding hepatic metastases exhibited decreasing ADC values, suggesting a potential inverse relationship between ADC and T1 SI changes in metastases versus primary tumors.
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