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

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1 The follow-up of uterine fibroids treated with HIFU: role of DWI and Dynamic contrast-study MRI Poster No.: C-1137 Congress: ECR 2011 Type: Authors: Keywords: DOI: Scientific Exhibit V. Zampa, V. Vallini, S. Ortori, F. Porcelli, C. Bartolozzi; Pisa/IT Treatment effects, MR-Diffusion/Perfusion, MR, Pelvis, Interventional non-vascular, Genital / Reproductive system female, Ablation procedures, Neoplasia /ecr2011/C-1137 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 15

2 Purpose To evaluate the role of MRI: diffusion-weighted imaging (DWI) Dynamic contrast-study in assessing the response of uterine fibroids to high intensity focused ultrasound (HIFU) treatment. Methods and Materials From December 2008 to February 2010: 8 patients (mean age, 48 years, age range 46-52) with symptomatic uterine fibroids free of other pelvic pathology that required surgical intervention all patients underwent HIFU patients underwent MRI before and 6 months after treatment MAGNETIC RESONANCE IMAGING (MRI): multiplanar capacity and excellent soft tissue contrast resolution reflecting pathology Imaging protocol: 1.5-T MRI scanner and a multi-phased array coil (cardiac, 8 channels) T2-weighted FSE in the sagittal, axial; coronal planes when needed Dynamic-contrast study (FSPGR) DW imaging (b value= 500 sec/mm 2 ) images in the axial and sagittal planes MRI sequences parameters (Table 1) For each fibroid the following parameters were assessed: percentage of intralesional necrosis ADC value Percentage of contrast enhancement pre and post-treatment data were compared Page 2 of 15

3 DIFFUSION WEIGHTED IMAGING (DWI): Exploits the random motion of water molecules, a phenomenon otherwise known as Brownian motion or free diffusion. Within biologic tissue, the movement of water is impeded by interaction with tissue compartments, cell membranes and intracellular organelles. Water movement in tissues may be: intravascular, intracellular, extracellular The apparent diffusion coefficient (ADC) relates to the molecular translation movement of water molecules: decreased ADC values therefore correlate with increased tumor cellularity and total nuclear area, which act to restrict water diffusion an increase of ADC reflect the liquefactive necrosis, low cellularity [1] The mean ADC values of the lesion were measured in a circular region of interest (ROI) in one representative region as large as possible within the lesions from ADC maps on the Workstation. DYNAMIC CONTRAST STUDY: Contrast-enhanced MRI reflects the fibroid vascularity and allows to evaluate if the leiomyoma targeted for treatment is well vascularized (perfused), because leiomyomas with large areas of degeneration (no perfusion) would not benefit from HIFU treatment [2]. HIGH INTENSITY FOCUSED ULTRASOUND (HIFU): The HIFU technique is a new, non-invasive high precision procedure, considered as a valid alternative to surgery in the treatment of uterine fibroids. Ultrasound has two unique properties which allow it to be used for the ablation of solid tumors: it passes harmlessly through soft tissues may deposit enough energy in the focal region to cause localized tissue ablation. Page 3 of 15

4 The fine balance between transmission and deposition of energy is utilized to ablate leiomyomas in a non-invasive way. Tissue temperature within the local region is instantly raised to C during firstsecond of HIFU exposure; coagulation necrosis is therefore immediately induced in the tumor. Another important mechanism, through which cellular necrosis is obtained is an inert cavitation process resulting cell membranes rupture by jet phenomenon. Small tumor blood vessels of less than 2 mm diameter can be completely destroyed by HIFU [3]. Leiomyoma ablation is therefore caused by ischemic and mechanicalhyperthermic injury. The real benefit of this technique is to strike the target tissue with precision while sparing the normal surrounding structures [4, 5, 6]. Images for this section: Page 4 of 15

5 Fig. 1: Table 1 Page 5 of 15

6 Results Size before treatment: - Range : 5,2 cm to 15 cm - Mean : 7.8 cm Symptom presentation of 8 patients: - abdominal pain, menorrhagia, dysmenorrheal - 1,10 e -9 The mean ADC value of fibroids before treatment was: - range 0,42-1,40 e e -9 The mean ADC value of fibroids after treatment increased and was: - range 1,60-2,00 e -9 Median reduction in tumor size as a percentage of initial tumor volume at 6 months after HIFU treatment was of 65% Mean fibroid enhancement before treatment was: - 72% - range 54% to 83% Mean fibroid enhancement after treatment decreased to: - 22% - range 0% to 62% Results (Table 2) No severe complications were observed after HIFU ablation. Page 6 of 15

7 Follow up were performed in all patients with MRI 6 months after treatment. We show pre and post-treatment MRI data in one patient (Fig. 2, 3, 4, 5, 6, 7). Images for this section: Fig. 1: Table 2 Page 7 of 15

8 Fig. 2: a: Pretreatment MRI. Fast T2-weighted (FSE) image in the sagittal plane, shows a large, well circumscribed fibroid with inhomogeneous low signal intensity. b: Posttreatment MRI. On fat-suppressed FSE T2w image in the sagittal plane, signal intensity changes of the fibroid are appreciable; note the hypointense semilunar area in the posterior portion of the lesion (arrow). Page 8 of 15

9 Fig. 3: Pre-treatment and post-treatment axial DWI images and ADC maps. On pretreatment image (a) the lesion has low signal while post-treatment (b) the lesion displays change of the signal particularly in the anterior portion (arrow). On the ADC colorimetric maps pre (c) and post-treatment (d) the site of the ROIs are shown. In this case the ADC values resulted respectively 1,40 e-9 and 1,60 e-9. Page 9 of 15

10 Fig. 4: Pretreatment dynamic study. On the graph, green curve (1) reflects the fibroid enhancement. (2 miometrium, 3 muscle). Page 10 of 15

11 Fig. 5: Post-treatment dynamic study reveals an overall marked decrease of the enhancement of the lesion. (1 fibroid enhancement, 2 miometrium, 3 muscle). Page 11 of 15

12 Fig. 6: Post-treatment dynamic study. On the graph, the green curve (1) reflects the peripheral portion of the lesion still vascularized. (3 miometrium, 4 necrotic portion of the fibroid). Page 12 of 15

13 Fig. 7: Example of necrotic area calculation. The total fibroid area (a) and intralesional necrosis area (b) selected and measured on T1W-postcontrast images on pre and posttreatment images, respectively. Page 13 of 15

14 Conclusion HIFU ablation appears to be an effective and safe treatment in reducing uterine fibroids volume. Both dynamic study and DWI may serve as imaging tools to assess treatment response. In spite of the expected reduction of ADC values related to coagulative necrosis, we observed an increase of ADC values. This data should be confirmed in a larger study group and can be a matter of speculation in understanding the cellular effect of HIFU. Further studies are needed to understand the reliability of DWI and, particularly, if this technique can replace the dynamic study, thus avoiding the need of contrast media injection. References [1]. O. Kilickesmez, et al. Quantitative Diffusion-Weighted Magnetic Resonance Imaging of Noral and Diseased Uterine Zones. Acta Radiol 2009(3) [2]. Sala E, et al. The role of dynamic contrast-enhanced and diffusion weighted magnetic resonance imaging in the female pelvis. Eur J Radiol (2010), doi: / j.ejrad [3]. MITSUYOSHI I, et al. BLOOD FLOW OCCLUSION VIA ULTRASOUND IMAGE- GUIDED HIGHINTENSITY FOCUSED ULTRASOUND AND ITS EFFECT ON TISSUE PERFUSION. Ultrasound in Med. & Biol., Vol. 33, No. 3, pp , 2007 [4]. J E KENNEDY, et al. High intensity focused ultrasound: surgery of the future? The British Journal of Radiology, 76 (2003), [5]. Stewart EA, Gedroyc WM, Tempany CM, et al. Focused ultrasound treatment of uterine fibroid tumors: safety and feasibility of a noninvasive thermoablative technique. Am J Obstet Gynecol 2003; 189:48-54 [6]. Ren XL, Zhou XD, Zhang J, et al. Extracorporeal Ablation of Uterine Fibroids With High-Intensity Focused Ultrasound: Imaging and Histopathologic Evaluation. J Ultrasound Med 2007; 26: Page 14 of 15

15 Personal Information Dr Virna Zampa, Dr Valentina Vallini Diagnostic and Interventional Radiology Department of Oncology, Transplants and Advanced Technologies in Medicine University of Pisa via Paradisa 2, Pisa Page 15 of 15