Magnetic resonance-based total liver volume and magnetic resonance-diffusion weighted imaging for staging liver fibrosis in mini-pigs

AIM:To determine whether and how magnetic resonance imaging(MRI)-based total liver volume(TLV) and diffusion weighted imaging(DWI) could predict liver fibrosis.METHODS:Sixteen experimental mature mini-pigs(6 males,10 females),weighing between 20.0 and 24.0 kg were prospectively used to model liver fibrosis induced by intraperitoneal injection of 40% CCl4 dissolved in fat emulsion twice a week for 16 wk,and by feeding 40% CCl4 mixed with maize flour twice daily for the subsequent 5 wk.All the survival animals underwent percutaneous liver biopsy and DWI using b = 300,500 and 800 s/mm2 followed by abdominal gadolinium-enhanced MRI at the 0,5th,9th,16th and 21st weekend after beginning of the modeling.TLV was obtained on enhanced MRI,and apparent diffusion coefficient(ADC) was obtained on DWI.Hepatic tissue specimens were stained with hematoxylin and Masson' s trichrome staining for staging liver fibrosis.Pathological specimens were scored using the human METAVIR classification system.Statistical analyses were performed to determine whether and how the TLV and ADC could be used to predict the stage of liver fibrosis.RESULTS:TLV increased from stage 0 to 2 and decreased from stage 3(r = 0.211;P < 0.001).There was a difference in TLV between stage 0-1 and 2-4(P = 0.03) whereas no difference between stage 0-2 and 3-4(P = 0.71).TLV could predict stage ≥ 2 [area under receiver operating characteristic curve(AUC) = 0.682].There was a decrease in ADC values with increasing stage of fibrosis for b = 300,500 and 800 s/mm2(r =-0.418,-0.535 and-0.622,respectively;all P < 0.001).Differences were found between stage 0-1 and 2-4 in ADC values for b = 300,500 and 800 s/mm2,and between stage 0-2 and 3-4 for b = 500 or 800 s/mm2(all P < 0.05).For predicting stage ≥ 2 and ≥ 3,AUC was 0.803 and 0.847 for b = 500 s/mm2,and 0.848 and 0.887 for b = 800 s/mm2,respectively.CONCLUSION:ADC for b = 500 or 800 s/mm2 could be better than TLV and ADC for b = 300 s/mm2 to pre-dict fibrosis stage ≥ 2 or ≥ 3.

Wedge and needle liver biopsies show discordant histopathology in morbidly obese patients undergoing Roux-en-Y gastric bypass surgery

Background:Controversy exists over whether or not single-needle liver biopsies are sufficient to compare histological parameters in patients with non-alcoholic fatty liver disease.Aims:To identify sampling variability,we biopsied four liver specimens per patient,based on biopsy size(needle vs wedge)and location(left vs right lobe),immediately prior to bariatric Roux-en-Y gastric bypass surgery.Methods:Ten prospectively enrolled,morbidly obese patients underwent 40 laparoscopy-guided biopsies;two needle and two wedge from each of 16 left and 16 right liver lobes.The Kappa coefficient for concordance compared histological parameters from left and right lobe needle-and wedge biopsies.Wedge biopsies were considered our‘Gold Standard’.Results:Each patient had two wedge-and two needle liver biopsies.Kappa concordance between all needle and wedge biopsies from right and left lobes showed variability.Wedge-and needle liver biopsies from contralateral lobes had higher concordance with each other,compared to ipsilateral needle/wedge biopsy pairs.Contralateral wedge pairs had higher concordance than contralateral needle/needle pairs.There were no biopsy complications.Conclusions:Wedge biopsy pairs had the best Kappa concordance but contralateral needle/needle biopsy pairs had good Kappa concordance.There were no complications from the 40 needle-and wedge liver biopsies,confirming the safety of laporoscopic multi-biopsy in both liver lobes.