This document discusses using MRI to follow up on uterine fibroids treated with HIFU. It explains that HIFU induces coagulative necrosis in tumor tissue by rapidly raising the temperature. An MRI study assessed percentage of intralesional necrosis by measuring ADC values and contrast enhancement pre and post-treatment. The study found increased ADC values reflected liquefactive necrosis, while contrast enhancement decreased after treatment. Both dynamic contrast MRI and DWI can effectively assess the treatment response and reduction in tumor size and enhancement due to coagulative necrosis.

1. HIFU
The follow-up of uterine fibroids treated with HIFU: role
of DWI and Dynamic contrast-study MRI

2. Mechanism of action
• Tissue temperature within the local region is instantly raised to 65-
100°C during first second of HIFU exposure; coagulation necrosis is
therefore immediately induced in the tumor.
• The real benefit of this technique is to strike the target tissue with
precision while sparing the normal surrounding structures.

3. Aim of MRI study
•Assessment of the percentage of intralesional
necrosis:-
• ADC value.
• Percentage of contrast enhancement.
• pre and post-treatment data were compared.

4. ADC value`
• The increase of ADC after treatment reflects the liquefactive
necrosis, and low cellularity.

5. Contrast enhancement
Marked contrast enhancement before HIFU
treatment.
Central core of non enhancing necrotic
area after treatment.

6. Size reduction and signal alteration
after treatment.
Leiomyoma before and after HIFU treatment

7. Conclusion
• HIFU ablation is an effective and safe treatment in
reducing uterine fibroids volume.
• • Both dynamic study and DWI may serve as imaging
tools to assess treatment response.
• • There is reduction in the tumor volume and contrast
enhancement with elevation in the ADC values (related
to intralesional coagulative necrosis).