Clincal Application Value Of Diffusion Weighted Imaging And Perfusion Weighted Imaging In The Diagnosis Of Focal Hepatic Lesions

Part I Clincal application value of diffusion weighted imaging with different b values and measurement regions in the diagnosis of focal hepatic lesions.Objective:To quantitatively investigate the parameters of diffusion-weighted imaging (DWI) in differential diagnosis of focal hepatic lesions with different b values and measurement regions.Methods:54 patients with focal hepatic lesions (14 hepatocellular carcinomas,20 liver metastasizes,8 hemangiomas,12 hepatic cysts underwent DWI by utilizing a SE-EPI sequence with the respiratory-triggered technique during free breathing and spatial pre-saturation technique. The DWI scanning time was 1 min 27 s. The ADC value and eADC value with low (50,150 s/mm2), moderate (400> 500 s/mm2), high (750,1000 s/mm2) b values was analyzed on the entire lesions, margins and center regions. The signal-to-noise ratio (SNR) was calculated. ADCper and eADCper was calculated with the differences in ADC and eADC values between low and high b values. The ratios of ADC value and eADC value of entire HCC and liver metastasis to adjacent hapatic parenchyma were measured with different b values. The differences of all measured parameters with different b values between liver focal lesions were compared between lesion margins and center regions. ADCperand eADCper values of HCC and liver metastasis were compared with different b values.Results:(1)With the increase of b values, the SNR of DWI image was decrease. Linear relationship between b values and SNR was found. (2) No difference in ADC or eADC value with low b value was found in liver focal lesions (p>0.05); the difference in both ADC and eADC values of the entire lesion, center regions and margins of between benign and malignant lesions with moderate b value was found (P<0.05); The differences in both ADC and eADC values with high b value between benign and malignant leisions of the entire lesion and margins and center regions was also significant (p<0.05). (3) The difference of both ADCPCT and eADCper of entire leisions, margins and center regions between benign and malignant lesions had statistical significance (P<0.05). (4) The differences in ADC1-to-1 ratio and eADC 1-to-1 of malignant lesions between margins and center was detected (P<0.05), but not for benign ones (P>0.05). (5) The differences of both ADCper and eADCper value between HCC and metastasizes with low, moderate, high b value was not found (P>0.05). (6) The difference of both ADC1-to-1 and eADC 1-to-1 ratio with high b value between entire HCC and liver metastasis was found(P<0.05).Conclusions:DWI is a effective and precise method for differentiating liver benign and malignant lesions with high b value. ADC1-to-1 and eADC 1-to-1 ratio of entire lesions are reliable indexes in differential diagnosis between HCC and liver metastasis. The ADCper and eADCper value could provide valuable information to distinguish hepatic malignant and benign lesions.Part II Clincal application value of perfusion weighted imaging in the diagnosis of focal hepatic lesionsObjective:The aim of this study is to explore the value of perfusion weighted imaging to the diagnosis and differentiation of hepatic focal diseases and the value of clinical application by analysising the characterization and perfusion parameters of PWI of different hepatic focal diseases.Methods:PWI was performed in 42 patients including 14 Hepatocellular carcinoma (HCC),20 metastases,8 hemangioma with FSPGR sequence. The PWI image was processed to produce time-intensity curve (TIC) of HCC, metastases and hemangioma at the Functool 2 software in the MR scanning machine. The perfusion parameters include time to peak (TTP), maximam slope of increase (MSI), signal enhancement ratio (SER), positive enhancement Integral (PEI), mean time to enhance (MTE) were calculated depending on the TIC of hepatic focal lesions. The rainbow images were reconstructed for every perfusion parameters.Results:(1) TIC curve:the TICs of most HCC were quickly rise and fall or quickly rise and slowly fall; The metastases were lack of blood supply. The TICs of metastases was a low and flat curve. The base line, the rise slope and its amplitude were very lower than that of hepatic parenchyma. The TICs of hemangioma was slowly rise and slowly fall or slowly rise without significant decrease curve. (2) The value of TTP of HCC was lower than adjacent hepatic parenchyma and normal liver, and there were statistical significance (P<0.05). The value of MSI of HCC was higher than adjacent hepatic parenchyma and normal liver, and there were statistical significance (P<0.05). The value of PEI of center region of HCC was significant lower than margins and there was statistical significance (P<0.05), so as to the value of SER. The value of SER of HCC was higher than adjacent hepatic parenchyma and normal liver and there was statistical significance (P<0.05). (3) The value of TTP of metastases was higher than adjacent hepatic parenchyma and normal liver, and there was statistical significance (P<0.05). The value of SER of center region of metastases was significant lower than margins and there was statistical significance (P<0.05). The value of SER of metastases and adjacent hepatic parenchyma was higher than normal liver, and there were statistical significance (P<0.05). (4) The value of MSI of center region of hemangioma was significant lower than margins and there was statistical significance (P<0.05). The value of PEI of center region of hemangioma was significant lower than margins and there was statistical significance(P<0.05). The value of PEI of hemangioma was higher than normal liver, and there were statistical significance (P<0.05). The value of SER of center region of hemangioma was significant lower than margins and there was statistical significance (P<0.05). The value of SER of hemangioma was higher than normal liver, and there were statistical signif icance (P<0.05). The value of MTE of hemangioma was higher than normal liver, and there were statistical significance (P<0.05). (5) The value of MSI of HCC is significantly higher than metastases, hemangioma and normal liver. The value of PEI of hemangioma is significantly higher than HCC, metastases and normal liver. The value of SER of HCC and metastases is higher than hemangioma and normal liver. The value of MTE of hemangioma Is higher than HCC, metastases and normal liver. The value of TTP of metastases is higher than HCC, hemangioma and normal liver.Conclusions:Perfusion weighted imaging in hepatic focal disease is a fast and safe imaging technique, which is helpful for diagnosis of hepatic focal diseases. It could reflect hemodynamic changes of hepatic focal diseases and detect the early liver metastases that could not be diagnosised only by naked eye. PWI also could provide valuable information for clinical treatment and prognosis.