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A prospective multi-model study on comparative analysis of MRI with 18F-FAPI or 18F-FDG PET/CT to detect intestinal fibrosis in Crohn’s disease
Zhoulei Li1, Yangdi Wang1, Ruonan Zhang1, Siyun Huang1, Chen Zhao2, Shi-Ting Feng1, and Xuehua Li1
1Radiology Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China, 2MR Research Collaboration Team, Shanghai, China

Synopsis

Motivation: The accurate diagnosis of intestinal fibrosis is very important for CD management.

Goal(s): The characterization of intestinal fibrosis by using non-invasive imaging techniques on intestinal lesions with various fibrosis and inflammation, to explore the optimal clinical applications for commonly used imaging techniques in clinical practice for fibrotic diagnosis, providing valuable insights for clinical decision-making.

Approach: PET/CT and MTI were performed on animal and patient to investigate their efficiency on analyzation of intestinal fibrosis.

Results: The diagnostic effect of 18F-FAPI PET/CT in detecting CD fibrosis surpasses that of 18F-FDG PET/CT, while comparable to MTI, and offers great potential in early detection of intestinal fibrosis.

Impact: MTI is the most accurate technique for detecting intestinal fibrosis. 18F-FAPI PET/CT represents an optimal imaging technique currently, in terms of early fibrosis detection. However, its interpretation with fibrosis still requires caution due to the slight susceptibility to co-existing inflammation.

Accurate and early detection of Crohn's disease (CD) induced intestinal fibrosis is crucial for effective clinical management, yet it remains an unmet requirement. The magnetization transfer MR Imaging (MTI) was reported to offer high accurancy for detection of intestinal fibrosis1. Recently, the utilization of fibroblast activating protein inhibitor (FAPI) PET/CT has emerged as a promising tool for assessing fibrosis2-4. The diagnostic efficacy of 18F-FAPI PET/CT in detecting intestinal fibrosis was compared with that of 18F-FDG PET/CT and MTI. To do so, twenty-two rats were treated with TNBS for 2-4 weeks to simulate fibrosis development, and multi-model quantitative imaging was performed during a week. The mean and maximum standardized uptake values (SUVmean and SUVmax) were calculated on 18F-FAPI and 18F-FDG PET/CT, as well as the normalized magnetization transfer ratio on MTI (normalized MTR). Pathological evaluation of intestinal fibrosis was performed, and MTI was used as the imaging standard for fibrotic analysis. Imaging and pathological criteria were used to compare the diagnostic effects of fibrosis imaging parameters. Ten patients with 34 cases of intestinal stenosis were prospectively recruited to validate their diagnostic performance using the same imaging protocol. In patients, the accuracy of MTI (AUCs=0.90-0.91, P≤0.05) was comparable to FAPI uptake (AUCs=0.80-0.87, both P≤0.01) but higher than that of FDG uptake in distinguishing between non-to-mild and moderate-to-severe fibrosis (AUCs=0.53-0.82, P=0.01-0.36). In rats, FAPI uptake showed a rapid response to intestinal fibrosis at an early disease phase (week 0-2) and demonstrated a significant increasing trend with prolonged treatment duration (week 0-4;). In contrast, normalized MTR and FDG uptake presented only a minimal response at week 2 and did not correlate so clearly with treatment duration. Consistently, in early disease phase (rats treated till week 2), the correlations of FAPI uptake (SUVmean: R=0.69) with fibrotic scores were stronger than those of FDG uptake (SUVmean: R=0.17) and normalized MTR (R=0.52). In late disease phase (rats treated till week 3 or 4), normalized MTR (R=0.93) showed stronger correlations with fibrotic scores than FAPI uptake (SUVmean: R=0.55) or FDG uptake (SUVmean: R=0.19). In conclusion, MTI and 18F-FAPI PET/CT offer equal performance for characterization of intestinal fibrosis in Crohn's disease and has significant advantages compared to 18F-FDG PET/CT. It is worth to note that in accurately identifying early-stage intestinal fibrosis, 18F-FAPI PET/CT demonstrates vast potential and outperforms the performance of the other two imaging modalities, warranting further research.

Acknowledgements

No acknowledgement found.

References

1. Li XH, Mao R, Huang SY, et al. Characterization of Degree of Intestinal Fibrosis in Patients with Crohn Disease by Using Magnetization Transfer MR Imaging. Radiology 2018; 287(2): 494-503.

2. Luo Y, Pan Q, Yang H, Peng L, Zhang W, Li F. Fibroblast Activation Protein-Targeted PET/CT with (68)Ga-FAPI for Imaging IgG4-Related Disease: Comparison to (18)F-FDG PET/CT. Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2021; 62(2): 266-71.

3. Röhrich M, Leitz D, Glatting FM, et al. Fibroblast Activation Protein-Specific PET/CT Imaging in Fibrotic Interstitial Lung Diseases and Lung Cancer: A Translational Exploratory Study. Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2022; 63(1): 127-33.

4. Scharitzer M, Macher-Beer A, Mang T, et al. Evaluation of Intestinal Fibrosis with (68)Ga-FAPI PET/MR Enterography in Crohn Disease. Radiology 2023; 307(3): e222389.

Proc. Intl. Soc. Mag. Reson. Med. 32 (2024)
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DOI: https://doi.org/10.58530/2024/5156