| Part I Clincal application value of dynamic contrast enhanced MR scanning in the diagnosis of focal hepatic lesions.Objective: To evaluate Propeller LAVA dynamic contrast enhanced MR scanning in the diagnosis of focal hepatic lesions.Methods: 86 patients with focal hepatic lesions ( 51 hepatocellular carcinomas, 2 intrahepatic peripheral cholangiocarcinomas, 5 metastasises, 3 focal nodular hyperplasias, 12 hemangiomas, 7 hepatic cysts and 6 liver abscesses ) underwent conventional MR scanning ( T1WI and T2WI ) and Propeller LAVA dynamic contrast enhanced MR scanning. After the scanning ,the images were pushed into the workstation ADW 4.2 and then the hepatic artery , portal vein and hepatic vein were reconstructed by maximum intensity projection, multiplanner reconstruction and volume render.Results: 84 of 126 HCC lesions showed strong enhancement in the arterial phase and washout in the portal venous phase and delay phase; 20 of 126 HCC lesions showed strong enhancement in the arterial phase and isointense to the surrounding hepatic parenchyma in the portal venous phase and delay phase; 14 of 126 HCC lesions were observed hypointense to the surrounding hepatic parenchyma only in the delay phase. The feeding artery(16/126), the pseudocapsule (67/126) and tumorthrombus in the portal vein(5/49)were seen in some case of HCC. The intrahepatic peripheral cholangiocarcinomas were observed slightly heterogeneous ring enhancement in the arterial phase and ring enhancement in the portal phase and delay phase. Metastasises were oberserved no enhancedment(19/27) or ring enhancement surrounding thelesions(8/27) in the arterial phase and ring enhancement in the portal enhancement and the delay phase. Focal nodular hyperplasias showed complete homogeneous hyperintense on early and delayed phase. 45 of 49 hemangiomas showed a nodular peripheral enhancement with centripetal filling in delayed phase plasias. The hepatic cysts showed no enhancement. The liver abscesses were observed slightly enhancement in the arterial phase and obvious ring enhancement in the portal phase and delay phase.Conclusions: Various hepatic focal lesions have different enhancement patterns on the dynamic scans. Propeller LAVA dynamic contrast enhanced MR scanning is a useful method in diagnosis of focal liver lesions.Part II Clincal application value of diffusion weighted imaging in the diagnosis of focal hepatic lesions.Objective: To study the differential diagnosis value of diffusion-weighted imaging and apparent diffusion coefficient in focal hepatic lesions.Methods: 10 healthy volunteers and 78 patients with focal hepatic lesions ( 28 hepatocellular carcinomas, 1 intrahepatic peripheral cholangiocarcinoma, 15 metastasises, 6 focal nodular hyperplasias, 12 hemangiomas, 11 hepatic cysts and 5 liver abscesses ) underwent DWI by using a SE-EPI sequence ( b=600 s/mm2 ) . Among of them, 10 healthy wolunteers ,10 hepatocellular carcinomas, 5 focal nodular hyperplasias, 8 hemangiomas, 8 hepatic cysts underwent DWI with four b value ( 400,600,800,1000 s/mm2 ). The scanning time was 1 min 55 s. After the scanning, the signal-to-noise ratio(SNR), contrast-to-noise(CNR) and apparent diffusion coefficient(ADC) value were calculated. Results: There were negative correlation between b value and the SNR of the healthy volunteers ( r = -0.969 ; P = 0.000 ) , between b value and the lesion-liver CNR ( hepatocellular carcinoma, focal nodular hyperplasia, hemangioma, hepatic cyst ;r=-0.974,-0.921,-0.976,-0.969;P=0.000 ), beween b value and the ADC Value of focal hepatic lesion(hepatocellular carcinoma, focal nodular hyperplasia, hemangioma, hepatic cysts ; r=-0.784,-0.905,-0.968,-0.814;P=0.000). when b was 600s/mm2 , the ADC values of primary hepatic carcinoma(PHC), metastasis, focal nodular hyperplasia, hemangioma, hepatic cyst and liver abscess were(0.86±0.29)×10-3 mm2/s,(0.91±0.23)×10-3 mm2/s,(1.22±0.49)×10-3 mm2/s,(1.52±0.36)×10-3 mm2/s,(2.39±0.41)×10-3 mm2/s and(3.22±0.17)×10-37 mm2/s, respectively. And the healthy volunteer was (1.49±0.11) mm2/s. ADC value of the PHC and metastasis was lower than that of the healthy volunteer. ADC value of the hemangioma and hepatic cyst was higher then that of the healthy volunteers. There were no statistic differences among focal nodular hyperplasia, hepatic cyst and the healthy volunteer. Use of a threshold ADC value less than 1.15×10-3 mm2/s for the diagnosis of malignant lesions resulted in sensitivity and specificity of 92.23% and 95.59%, respectively .Conclusions: The focal hepatic lesions can be easily diagnosed and distinguished according to DWI, ADC value and their changing characteristics. So, DWI has an important clinical value in the diagnosis of focal hepatic lesions.Part III Magnetic Resonance Spectroscopy Quantitative Analysis in the Differential diagnosis of focal hepatic lesionsObjective: To evaluate Magnetic Resonance Spectroscopy Quantitative Analysis in the diagnosis of focal hepatic lesions.Methods: 64 patients with focal hepatic lesions ( 28 hepatocellular carcinomas, 1 intrahepatic peripheral cholangiocarcinoma, 8 metastasises, 6 focal nodular hyperplasias, 12 hemangiomas, 7 hepatic cysts and 2 liver abscesses ) underwent conventional MR scanning ( T1WI and T2WI ) and MRS scanning. Localized proton MR spectra with a voxel size of 8 were obtain in the focal hepatic lesions and in the hepatic parenchyma in the same patient as control. After volume-seletive autoshimming of the voxels, the spectra was obtained with a point-resolve spectroscopy technique ( TR=1265 ms, TE=144 ms,NEX=8,scan time 1 min 11 s) with water suppresion. And then the peak value and the area under the peak of cho and lip were caculated.Result: Compared with the hepatic parenchyma ,The peak value and the area under the peak of cho in PHC was higher(t=5.4026,4.7484;P=0.000,0.000),the peak vule and the area under the peak of cho/lip was higher too(t=2.5711,2.1455;P=0.015,0.041);The peak value and the area under the peak of cho in metastasis was higher than the hepatic parenchyma(t=3.6583,8.9184;P=0.008,0.000); The the peak value and the area under the peak of lip in focal hepatic lesions was lower than the hepatic parenchyma(t=-3.6581,-3.1700;P=0.020,0.025); The the peak value of cho and lip and the area under the peak of lip in hemangioma was lowerr than the hepatic parenchyma(t=-4.4629,-5.9614,-3.1663;P=0.001,0.001,0.009), the area under the peak of cho/lip was higher then the hepatic parenchyma(t=3.4237,P=0.006); The cho and lip in hemangioma was lower than the hepatic parenchyma, the cho/lip was higher then the hepatic parenchyma.There was significent statistic difference between the malignant tumor and benign lesions in the peak value and the area under the peak of cho and lip(F=-5.2090,-5.4821,-4.9229,-5.4180;P=0.000,0.000,0.000,0.000).Conclusions: MRS may show the metabolic changes in the focal hepatic lesions noninvasingly, and it is helpful for the differential diagnosis between benign and malignant lesions.
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