Evaluation of experimentally induced early hepatic alveolar echinococcosis in rats with MRI-DWI Zeng Hongchun，Liu Wenya* Imaging center, The First affiliated hospital, Xinjiang medical university, Urumqi, China Innovation for the Management of Echinococcosis Symposium, Besançon, March 27, 2014

Background Early diagnosis Dynamic follow-up Hepatic Alveolar Echinococcosis (HAE) is a potentially fatal parasitic inflection like malignant disease Early diagnosis The disease remains thus underdiagnosed It’s like an infectious cancer, so early diagnosis would be vital Dynamic follow-up Chemotherapy with benzimidazoles have increasiongly been used in treatment of AE

Imaging method for HAE Us Computed tomography（CT) Magnetic Resonance Imaging(MRI) PET-CT SPECT Now

Technology comparison PET SPECT CT MR Information Functional Anatomical Both Anatomical Detail Poor Good Excellent Soft Tissue Differentiation - - - Ionizing Radiation Yes No Spatial Resolution (clinical) 3-8 mm 8-15 mm 1 mm Activity of HAE Poor*

Background Staging diagnosis Activity Early MR-DWI A promising technique for characterizing HAE Staging diagnosis Early Activity With recent developments in gradient technol- ogy, multichannel coils, echo-planar sequences, and parallel imaging techniques, diffusion- weighted imaging has become a promising technique for characterizing lesions. Diffusion- weighted imaging exploits the microscopic ran- dom mobility of water protons to measure the diffusion of fluid in tissue (34,37–39).Tissue regions with restricted water diffusion (eg, malig- nant lesions) are displayed as regions of high signal intensity. Signal intensity at diffusion-weighted imaging can be quantified by calculating the apparent diffusion coefficient (ADC), a valuable indicator for the diagnosis and characterization of focal hepatic lesions (34,40,41).The movement of water molecules in malignant tumors, unlike that in alveolar echinococcosis lesions, is restricted because of increased cellularity and reduced ex- tracellular space (42). Alveolar echinococcosis lesions can be reliably identified on diffusion- weighted images obtained with b values of 0, 50, 400, and 800 sec/mm2 and qualitatively assessed on ADC maps. Typically, the lesions appear hypointense on T1-weighted and T2-weighted images, as well as on diffusion-weighted images，obtained with a b value of 800 sec/mm2, which results in a subjectively higher ADC in the lesion than in liver parenchyma (Fig 12). Restricted dif- fusion due to a superinfection (ie, an abscess) may be observed in the necrotic central part of par- ticularly large alveolar echinococcosis lesions.The general lack of diffusion restriction in alveolar echinococcosis lesions is an important finding that helps differentiate them from malignancies that have similar clinical features and imaging findings, including invasion and metastases. Ta- ble 1 summarizes characteristic imaging features that are helpful for diagnosing hepatic alveolar echinococcosis. Mecit K, et al. RSNA 2012, 2053.

? Diagnosis –Anatomic and Metabolic Imaging of DWI Application of DWI for HAE Early diagnose Differentiation Follow up exploit

Purpose To find the best scanning parameter in early detection of HAE infected rats with MR-DWI Characterizing the features of HAE of rat with MRI-DWI To verify the value of MRI-DWI in detecting early HAE of rat Ethics committee approval of a study

Material & Methods The experimentally induced HAE in 40 rats were studied after testified by US MR-DWI scans(GE 3. 0 T Signa Eexcite) Routing T1WI and T2WI DWI obtained with b values of 300~800sec/mm2 with internal 100 sec/mm2 ADC measuring ROI were placed on the marginal zone, center area of the lesion as well as nearby liver perenchyma, Avoiding calcification, vessels and bile duct Follow up: early(9 weeks), middle(28 weeks), late(50weeks) Pathological exam of removed liver ：ROI were placed on the marginal zone, solid component area of the lesion as well as nearby liver perenchyma

Material & Methods Anesthesia and injection MR Scan with wrist coil Under oper surgery looking Anesthesia and injection MR Scan with wrist coil (GE 3.0T Signa HDx System)

(Intermediate and advanced stage) Results The detection rate of MR for HAE in rats HAE (Early stage) (Intermediate and advanced stage) MR-T2WI 82.5% (33/40) 100%(40/40) MR-DWI(b=500) MR-DWI(b=700) 77.5%（31/40） 97.5%（39/40）

Results MRI-T1\T2 findings of different stage of HAE in rats Early stage(9 weeks)

Results MRI-T1\T2 findings of different stage of HAE in rats Middle stage (28 weeks)

Results MRI-T1\T2 findings of different stage of HAE in rats Later stage (50 weeks)

Results MRI-DWI of different stage of HAE in rats b value of 500 sec/mm2

Results Macropathology of different stage of HAE in rats

Results Pathological changes of different stage of HAE in rats

Normal liver parenchyma Results Comparison of ADC value between the marginal zone, center area of the lesion and normal liver parenchyma Early stage Middle stage Later stage Marginal zone ++ + Center area Normal liver parenchyma

Results ADC value vs Pathologic features Margin zone The lower signal surrounding the lesion is the inflammatory belt in early stage, which was rich in micro-blood vessels and fibrotic tissue, as well as inflammatory cells Fibrosis ADC value Areas of low signal intensity of DWI correspond to fibrotic or collagenous components. DWI Margin zone Pathology

Results Dynamic presentation of MR imaging of HAE in rats Early stage Middle stage Later stage T1WI low signal T2WI Uniformity high signal heterogeneous signal intensity DWI high signal Marginal zone:ring lower signal ，lunar halo sign Marginal zone: Slightly high signal High signal (areas of low and high signal intensity reflect the

Summary MR-DWI can be used in rat model of HAE MRI-DWI can demonstrate the characteristic features of early HAE in animal atudy ADC value can reflect the fibrosis degree of HAE in rats

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Author and correspondence address Zeng Hongchun Email:398023151@qq.com TEL: +86–991–15026031812