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Role of  whole-body DWI in  detection of tumour recurrence and metastasis by comparison with 18FDG PET-CT in patients with gastrointestinal cancer
Sikandar Mohd Shaikh1
1Yashoda Hospitals, Hyderabad, India

Synopsis

Twenty one patients with pathologically confirmed, newly diagnosed, untreated nodal metastases were included. DW images T2-weighted and T2-weighted SPAIR images were evaluated first, We used (18)F-FDG PET/CT as the standard of reference. True-positive, false-positive, and false-negative values were evaluated on a per-lesion basis. Tumor staging based on T2-weighted and T2-weighted SPAIR imaging without DWI and then with DWI was compared. True-positive lesions were increased from 89% to 97%, false-positive lesions were increased from 3% to 6%, and false-negative lesions were decreased from 11% to 3% by the addition of DWI.

AIMS AND OBJECTIVES: The primary aim of our study was to evaluate the diagnostic performance of conventional whole-body MRI and with diffusion-weighted imaging (DWI) in the detection of known (18)F-FDG-avid nodal metastases. The conventional whole-body MRI protocol consisted of a T2-weighted sequence and a T2-weighted sequence with frequency-selective fat suppression. The second protocol used the same sequences as the first protocol but also included DWI. MATERIAL AND METHODS: Twenty one patients with pathologically confirmed, newly diagnosed, untreated nodal metastases were included. T2-weighted and T2-weighted SPAIR images were evaluated first, separate from the DW images, and then were evaluated with the DW images. We used (18)F-FDG PET/CT as the standard of reference. True-positive, false-positive, and false-negative values were evaluated on a per-lesion basis. Tumor staging based on T2-weighted and T2-weighted SPAIR imaging without DWI and then with DWI was compared. RESULTS: True-positive lesions were increased from 89% to 97%, false-positive lesions were increased from 3% to 6%, and false-negative lesions were decreased from 11% to 3% by the addition of DWI. Diagnostic sensitivity was significantly increased (p = 0.002) by adding DWI. Lesions detected on DWI but not on T2-weighted and T2-weighted SPAIR imaging were located in pararenal (n = 1), paraaortic (n = 6), and pelvic (n = 3) lymph nodes. On DWI, 47% of the lesions (n = 55) were more conspicuous than on T2-weighted and T2-weighted SPAIR imaging; most of these lesions (58%, n = 32) were from in the pelvic or abdominal regions and bone marrow. No difference was found between T2-weighted and T2-weighted SPAIR imaging without DWI and T2-weighted and T2-weighted SPAIR imaging with DWI in nodal metastases for staging, being consistent with PET/CT in 88% of the patients (n = 15). CONCLUSION: DWI adds diagnostic value to conventional whole-body MRI sequences With technical optimization, whole-body MRI with DWI, as a nonionizing imaging modality, is significantlyuseful as an alternative method to PET/CT in the management of nodal metastases.

Acknowledgements

- Dr.Rammurti

References

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Proc. Intl. Soc. Mag. Reson. Med. 28 (2020)
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