Diffusion weighted imaging in the liver

Diffusion weighted magnetic resonance imaging (DWI) is an imaging technique which provides tissue contrast by the measurement of diffusion properties of water molecules within tissues. Diffusion is expressed in an apparent diffusion coefficient (ADC), which reflects the diffusion properties unique to each type of tissue. DWI has been originally used in neuroradiology. More recently, DWI has increasingly been used in addition to conventional unenhanced and enhanced magnetic resonance imaging (MRI) in other parts of the body. The reason for this delay was a number of technical problems inherent to the technique, making DWI very sensitive to artifacts, which had to be overcome. With assessment of ADC values, DWI proved to be helpful in characterization of focal liver lesions. However, DWI should always be used in conjunction to conventional MRI since there is considerable overlap between ADC values of benign and malignant lesions. DWI is useful in the detection of hepatocellular carcinoma in the cirrhotic liver and detection of liver metastases in oncological patients. In addition, DWI is a promising tool in the prediction of tumor responsiveness to chemotherapy and the follow-up of oncological patients after treatment, as DWI may be capable of detecting recurrent disease earlier than conventional imaging.This review focuses on the most common applications of DWI in the liver.

Diffusion weighted imaging for the detection and evaluation of cholesteatoma

Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium.It is trapped in the middle ear and can lead to bony erosion.The disease is treated surgically often followed by a second-look procedure to check for residual tissue or recurrence.Cholesteatoma has specific signal-intensity characteristics on magnetic resonance imaging with very high signal intensity on diffusion weighted imaging(DWI).Various DWI techniques exist:Echo-planar imaging(EPI)-based and non-EPI-based techniques as well as new approaches like multi-shot EPI DWI.This article summarizes all techniques,discusses the significance in detecting cholesteatoma and mentions actual studies.Further recommendations for daily clinical practise are provided.

1H magnetic resonance spectroscopy and diffusion weighted imaging findings of medulloblastoma in 3.0T MRI A retrospective analysis of 17 cases

1H magnetic resonance spectroscopy and diffusion weighted imaging features of the cerebellar vermis in 17 medulloblastoma patients were retrospectively analyzed, and 17 healthy volunteers were selected as controls. 1H magnetic resonance spectroscopy showed that in all 17 medulloblastoma patients, N-acetyl aspartate and creatine peaks were significantly decreased, the choline peak was significantly increased, and there was evidence of a myo-inositol peak. Further, 11 patients showed a low taurine peak at 3.4 ppm, five patients showed a lipid peak at 0.9-1.3 ppm, and three patients showed a negative lactic acid peak at 1.33 ppm. Compared with the control group, the ratios of N-acetyl aspartate/choline and N-acetyl aspartate/creatine were significantly decreased, and the ratio of choline/creatine was increased, in medulloblastoma patients. Diffusion weighted imaging displayed hyperintensity and decreased apparent diffusion coefficient in medulloblastoma patients. These findings indicate that 1H magnetic resonance spectroscopy and diffusion weighted imaging are useful for qualitative diagnosis of medulloblastoma.

Value of MRI diffusion weighted imaging in localization of prostate cancer with whole-mount step section pathology

Objective To evaluate the value of MRI diffusion weighted imaging in localization of prostate cancer with whole-mount step section pathology. Methods We treated 36 patients using laparoscopic radical prostatectomy from Oct. 2009 to Jun. 2010. Patients who did not have an MRL /DWI examination or a surgical history of pros-

Diffusion weighted magnetic resonance imaging of liver: Principles, clinical applications and recent updates

Diffusion-weighted imaging(DWI), a functional imaging technique exploiting the Brownian motion of water molecules, is increasingly shown to have value in various oncological and non-oncological applications. Factors such as the ease of acquisition and ability to obtain functional information in the absence of intravenous contrast, especially in patients with abnormal renal function, have contributed to the growing interest in exploring clinical applications of DWI. In the liver, DWI demonstrates a gamut of clinical applications ranging from detecting focal liver lesions to monitoring response in patients undergoing serial follow-up after loco-regional and systemic therapies. DWI is also being applied in the evaluation of diffuse liver diseases such as non-alcoholic fatty liver disease, hepatic fibrosis and cirrhosis. In this review, we intend to review the basic principles, technique, current clinical applications and future trends of DW-MRI in the liver.

Differential diagnosis of metastasis from non-metastatic lymph nodes in cervical cancers： pilot study of diffusion weighted imaging with background suppression at 3T magnetic resonance

Background Diffusion weighted imaging with background suppression （DWIBS） is potentially useful in detecting metastatic lymph nodes. This study aimed to evaluate the efficacy of DWIBS at 3T magnetic resonance （MR） for diagnosing metastatic lymph nodes in cervical cancer.Methods This retrospective study included 25 patients with cervical cancer who underwent MR examination and were treated by hysterectomy and lymphadenectomy. The metastatic and non-metastatic lymph nodes were histologically proven by operation. Apparent diffusion coefficient （ADC） values, long-axis diameters, short-axis diameters, ratio of short- to long-axis diameters of all the identifiable lymph nodes were measured and compared.Results Twenty-five primary tumor lesions, 17 metastatic lymph nodes and 140 non-metastatic lymph nodes were pathologically confirmed in 25 cases with cervical cancer. The difference of ADC values between primary tumor lesions,metastatic and non-metastatic lymph nodes were statistically significant （F=7.93, P=0.001）. There was no statistically significant difference between primary tumor lesions of cervical cancer and metastatic lymph nodes （t=-0.75, P=-0.456）,and the difference between primary tumor lesions and non-metastatic lymph nodes was statistically significant （t =4.68, P〈0.001）. The ADC values, long-axis diameters, short-axis diameters, ratio of short- to long-axis diameters of metastatic and non-metastatic lymph nodes were （0.86±0.36）×10-3 mm2/s vs. （1.12±0.34）×10-3 mm2/s, （1.51±0.41） cm vs.（1.19±0.36） cm, （1.16±0.35） cm vs. （0.77±0.22） cm, 0.78±0.17 vs. 0.68±0.19 respectively, and statistically significant difference existed between two groups.Conclusions DWIBS at 3T MR has the distinct advantages in detecting pelvic lymph nodes of cervical cancer.Quantitative measurement of ADC values could reflect the degree of restriction of diffusion of metastatic and non-metastatic lymph nodes. The combination of size and ADC value would be useful in the accurate diagnosis of metastatic lymph nodes.

In vivo evaluation of renal function using diffusion weighted imaging and diffusion tensor imaging in type 2 diabetics with normoalbuminuria versus microalbuminuria

This work aims to estimate the value of diffusion weighted imaging （DWI） and diffusion tensor imaging （DTI） in detecting early-stage kidney injury in type 2 diabetic patients with normoalbuminuria （NAU） versus microalbuminuria （MAU） prospectively. A total of 30 T2DM patients with normal kidney function were recruited and assigned to the NAU group （n = 14） or MAU group （n = 16） according to 8 h overnight urinary albuminuria excretion rate （AER） results. A contemporary cohort of health check-up recipients were included as controls （n = 12）. DWI and DTI scans were performed on bilateral kidney using SE single-shot EPI, and apparent diffusion coefficient （ADC） and fractional anisotropy （FA） of the renal parenchyma was determined from ADC and FA maps of the three groups. ADC and FA values were compared among the three groups. According to DWI with a b value of 400 s/mm^2, the MAU and NAU groups showed significantly lowered mean ADC values compared with the healthy controls （P 〈 0.01）. The mean ADC in the MAU group [（2.22± 0.07） × 10^-3 mm^2/s] was slightly lower than that of the NAU group [（2.31 ± 0.22） × 10^- 3 mm^2/s], but this difference was not statistically significant （P 〉 0.05）. The FAvalue in the MAU group was higher than that in the control group （0.45 ± 0.07 vs. 0.3±0.03, P = 0.004） but did not differ from that in the NAU group （0.42 ± 0.03） （P 〉 0.05）. ADC and FA values may be more sensitive than urine AER in reflecting early-stage kidney injury and, hence, may facilitate earlier detection and quantitative evaluation of kidney injury in T2DM patients. Combined evaluation of ADC and FA values may provide a better quantitative approach for identifying diabetic nephropathy at early disease stages.

Diffusion-weighted magnetic resonance imaging reflects activation of signal transducer and activator of transcription 3 during focal cerebral ischemia/reperfusion

Signal transducer and activator of transcription（STAT）is a unique protein family that binds to DNA,coupled with tyrosine phosphorylation signaling pathways,acting as a transcriptional regulator to mediate a variety of biological effects.Cerebral ischemia and reperfusion can activate STATs signaling pathway,but no studies have confirmed whether STAT activation can be verified by diffusion-weighted magnetic resonance imaging（DWI）in rats after cerebral ischemia/reperfusion.Here,we established a rat model of focal cerebral ischemia injury using the modified Longa method.DWI revealed hyperintensity in parts of the left hemisphere before reperfusion and a low apparent diffusion coefficient.STAT3 protein expression showed no significant change after reperfusion,but phosphorylated STAT3 expression began to increase after 30 minutes of reperfusion and peaked at 24 hours.Pearson correlation analysis showed that STAT3 activation was correlated positively with the relative apparent diffusion coefficient and negatively with the DWI abnormal signal area.These results indicate that DWI is a reliable representation of the infarct area and reflects STAT phosphorylation in rat brain following focal cerebral ischemia/reperfusion.

Application Progress of Intravoxel Incoherent Motion Diffusion Weighted Magnetic Resonance Imaging in Pancreatic Cancer

Intravoxel incoherent motion imaging (IVIM), on the traditional diffusion weighted imaging (DWI) technology, uses the biexponential model and adopts the multi-b-value analysis to obtain the perfusion information of water molecule diffusion and microcirculation without the use of contrast agent. It is more and more used in pancreatic diseases, which is of great significance for the diagnosis and identification of pancreatic cancer. This article will review the principles of IVIM imaging and its application in pancreatic diseases, especially in pancreatic cancer diagnosis, the prediction of pathological grade of pancreatic ductal adenocarcinoma, the judgment of lymph node metastasis, and differentiation of pathological classification.

Monoexponential, biexponential and stretched-exponential models based diffusion weighted imaging: a comparative study in the differential diagnosis of benign and malignant breast lesions

Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A retrospective study was performed in 54 patients with pathologically confirmed malignant tumors(n=30),benign lesions(n=34)and normal fibroglandular

Value of Apparent Diffusion Coefficient(ADC) of Diffusion eighted Magnetic Resonance Imaging in Common Renal Disease Diagnosis

Objective：To find the value of the apparent diffusion coefficient （ADC） of diffusion weighted magnetic resonance imaging of common renal diseases. Methods： There were 30 healthy subjects and 81 patients with renal lesions （56 cases of renal carcinoma, 18 lesions of 12 cases of renal angiomyolipomal and 21 lesions of 13 cases of renal cysts）. Conventional magnetic resonance imaging and diffusion weighted magnetic resonance imaging were carried out. We measured the average ADC value of the renal lesions and normal kidneys. ADC maps from different b values were generated by a statistical package. Results： The ADC values of normal kidneys with three different motion-probing gradients（b=500, 800, 1000 sec/mm^2） were 2.78 ± 0.14 × 10^-3mm^2s^-1, 2.45 ± 0.13 × 10^3mm^2s^-1, 2.13 ± 0.14 × 10^-3mm^2s^-1, respectively. The ADC values of renal cell carcinoma with three different motion-probing gradients（b=500, 800, 1000 sec/mm^2） were 1.63 ± 0.14 × 10^3mm^2s^-1, 1.31 ± 0.18 × 10^3mm^2s^-, 1.07 ± 0.15 × 10^-3mm^2s^-1, respectively. Among the renal cell carcinoma, the ADC value of clear cell type were 1.67 ± 0.09 × 10^3mm^2s^-1, 1.36 ± 0.13 × 10^3mm^2s^-1, 1.15 ± 0.14 × 10^3mm^2s^-1,respectively; the ADC values of granular cell type were 1.59±0.19 × 10^3mm^2s^-1, 1.25 ± 0.22 × 10^3mm^2s^-1, 0.97 ± 0.12 × 10^3mm^2s^-1, respectively. The ADC values of renal angiomyolipoma with three different motion-probing gradients（b=500, 800,1000 sec/mm^2） were 0.88 ± 0.08 × 10^3mm^2s^-1, 0.63 ± 0.07 × 10^3mm^2s^-1, 0.43 ± 0.04 × 10^3mm^2s^-1, respectively. The ADC values of renal cystic lesions with three different motionprobing gradients（b=500, 800, 1000 sec/mm^2） were 3.73 ± 0.18 × 10^3mm^2s^-1, 3.44 ± 0.13 × 10^3mm^2s^-1, 3.09± 0.21 × 10^3mm^2s^-1, respectively. Statistically significant differences exists between the ADC values of normal kidney, renal carcinomas, renal angiomyolipomas and renal cysts when the b value is the same. Among the different cell types of renal carcinomas, the ADC value of granular cell carcinoma is lower than that of clear cell carcinomas. Conclusion： It is of benefit in diagnosing and distinguishing between benign and malignant renal tumors to know the ADC values in diffusion weighted magnetic resonance imaging. Furthermore, these values help to know the internal structure of the tumor and the tumor typel, which is helpful to the treatment and in predicting the patient＇ s prognosis.

Diffusion-weighted MRI in abdominal oncology:Clinical applications

Diffusion-weighted magnetic resonance imaging(DWI) provides image contrast that is different from that obtained by conventional magnetic resonance techniques.Although previously,DWI has been used to evaluate various diseases of the central nervous system,several technical advances have expanded the clinical applications of DWI beyond the central nervous system.As a result,many reports have been published on the use of DWI in abdominal diseases.Particularly,abdominal DWI has now being focused on evaluation of patients with abdominal cancer.DWI can be used for pretreatment tumor detection,characterization including predicting tumor response to therapy,monitoring tumor response during therapy,and follow-up study after treatment to detect possible tumor recurrence.

Susceptibility weighted imaging in the evaluation of hemorrhagic diffuse axonal injury

Diffuse axonal injury（DAI）is axonal and small vessel injury produced by a sudden acceleration of the head by an external force,and is a major cause of death and severe disability（Paterakis et al.,2000）.Prognosis is poorer in patients with apparent hemorrhage than in those without（Paterakis et al.,2000）.Therefore,it is important to identify the presence and precise position of hemorrhagic foci for a more accurate diagnosis.CT and magnetic resonance imaging（MRI）have long been applied in the diagnosis of DAI, but they are not sensitive enough for the detection of small hemorrhagic foci, and cannot meet the requirements for early diagnosis. A major advance in MRI has been the development of susceptibility weighted imaging （SWI）, which has greatly increased the ability to detect small hemorrhagic foci after DAI （Ashwal et al., 2006）.

Complementary comments on diagnosis,severity and prognosis prediction of acute pancreatitis

The radiological differential diagnosis of acute pancreatitis includes diffuse pancreatic lymphoma,diffuse autoimmune pancreatitis and groove located mass lesions that may mimic groove pancreatitis.Dual energy computed tomography and diffusion weighted magnetic resonance imaging are useful in the early diagnosis of acute pancreatitis,and dual energy computed tomography is also useful in severity assessment and prognosis prediction.Walled off necrosis is an important complication in terms of prognosis,and it is important to know its radiological findings and distinguish it from pseudocyst.

Apparent diffusion coefficient evaluation for secondary changes in the cerebellum of rats after middle cerebral artery occlusion

Supratentorial cerebral infarction can cause functional inhibition of remote regions such as the cerebellum, which may be relevant to diaschisis. This phenomenon is often analyzed using positron emission tomography and single photon emission CT. However, these methods are expensive and radioactive. Thus, the present study quantified the changes of infarction core and remote regions after unilateral middle cerebral artery occlusion using apparent diffusion coefficient values. Diffu- sion-weighted imaging showed that the area of infarction core gradually increased to involve the cerebral cortex with increasing infarction time. Diffusion weighted imaging signals were initially in- creased and then stabilized by 24 hours. With increasing infarction time, the apparent diffusion co- efficient value in the infarction core and remote bilateral cerebellum both gradually decreased, and then slightly increased 3-24 hours after infarction. Apparent diffusion coefficient values at remote regions （cerebellum） varied along with the change of supratentorial infarction core, suggesting that the phenomenon of diaschisis existed at the remote regions. Thus, apparent diffusion coefficient values and diffusion weighted imaging can be used to detect early diaschisis.

Advances in the imaging of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms comprise a heterogeneous group of tumors that differ in their pathogenesis,hormonal syndromes produced,biological behavior and consequently,in their requirement for and/or response to specific chemotherapeutic agents and molecular targeted therapies.Various imaging techniques are available for functional and morphological evaluation of these neoplasms and the selection of investigations performed in each patient should be customized to the clinical question.Also,with the increased availability of cross sectional imaging,these neoplasms are increasingly being detected incidentally in routine radiology practice.This article is a review of the various imaging modalities currently used in the evaluation of neuroendocrine neoplasms,along with a discussion of the role of advanced imaging techniques and a glimpse into the newer imaging horizons,mostly in the research stage.

Feasibility of establishing cerebral ischemia models by using aerocyst-blocking bilateral ascending pharyngeal artery of piglets Imaging assessment

BACKGROUND： The cerebral ischemia and ischemia/reperfusion animal models are used to simulate the human cerebrovascular diseases is one of the popular topics of neurological science recently. To study the pathophysiology, pathogenesis, prophylaxis and treatment of ischemic cerebrovascular diseases and to establish the ideal animal model that is the most similar to the human cerebral ischemia, are the topics that the people generally cared about. OBJECTIVE： To evaluate the effects of aerocyst-blocking bilateral ascending pharyngeal artery on the establishment of cerebral ischemia models by using digital subtraction angiography （DSA）, magnetic resonance diffusion-weighted imaging （DWI） and magnetic resonance perfusion-weighted imaging （PWI）. DESIGN： Repetitive measure animal experiment. SETTING： Zhongshan Hospital Affiliated to Dalian University. MATERIALS： The experiment was carried out in the Animal Laboratory （Provincial Laboratory）, Zhongshan Hospital of Dalian Univeristy from January to May 2006. A total of 14 domestic piglets, of 6 months old, weighing 12-15 kg, of either gender, were selected from Animal Experimental Center, Dalian University. Multistar T.O.P digital subtraction angiography machine was provided by Siemens Company, German. METHODS： Aerocyst-blocking bilateral ascending pharyngeal artery was used to establish cerebral ischemia models. And then, Multistar T.O.P. DSA was used for imaging of cerebral vessels before blocking, during blocking and at 0.5 and 2 hours after ischemia perfusion. GE Signa 1.5 T supraconduction magnetic resonance imaging was used for DWI examination; in addition, PWI was used based on focal sites and areas. Otherwise, magnetic resonance imaging （MRI） was used to detect signal changes of T1WI and T2WI in ischemic areas. MAIN OUTCOME MEASURES： Analytic results of DSA, DWI, PWI and MRI. RESULTS： All 14 experimental piglets were involved in the final analysis. ① DSA： The blood flow of bilateral ascending pharyngeal arteries and its branch were blocked at blocking phase, which restored 0.5 and 2 hours after reperfusion. ② DWI and PWI： There were no observable abnormalities in PWI and DWI at pre-blocking. Abnormal increased signals were found on both DWI and PWI at during and post-blocking. There were reduction in ADC and rCBF and delay in rTTP at all time points except pre-blocking. ③ MRI： There were no abnormal signals observable at any time of pre- and post-blocking in T1WI and T2WI. CONCLUSION： It is feasible to establish this kind of animal experimental models, and it can simulate the ischemic state; meanwhile, the existence and extent can be showed directly by DSA, DWI, and PWI.

Role of diffusion-weighted imaging in early ankylosing spondylitis

Background With the advanced MRI techniques, pathologic features can be detected at an early stage and quantitatively evaluated, resulting in the advantages of early diagnosis and prompt treatment. This study aimed to determine the value of diffusion-weighted MR imaging （DWI） in detection of early ankylosing spondylitis （AS） and investigate the characteristic manifestations of AS on whole body DWl （WB-DWl）. Methods Twenty patients with the diagnosis of early AS, twenty patients with low back pain （LBP）, and twenty-five healthy volunteers were included in this study. The subchondral bone apparent diffusion coefficients （ADC） among these groups in the bilateral ilia and sacrum along the sacroiliac joints were compared. An independent sample t-test was utilized to analyze ADC value differences among groups. P-values less than 0.05 denoted statistical significance. The mean ADC values of focal DWl lesions in AS patients were also measured. Whole body diffusion-weighted imaging was performed in fifteen additional AS patients, and analyzed with MIP and MPR techniques in comparison to conventional MR images in order to evaluate the ability to detect AS lesions with whole body DWI. Results Mean ADC values in AS patients were （0.518±0.122）×10^-3 mm2/s in the ilium and （0.503＋0.168）x103 mm2/s in the sacrum. These were significantly greater than the values measured in the ilium and sacrum of LBP patients, （0.328±0.053）×10^-3 mm2/s in the ilium and （0.311±0.081）×10^-3 m2/s in the sacrum, and control group, （0.325±0.015）×10-3 mm2/s in the ilium and （0.318±0.011）×10^-3 mm2/s in the sacrum respectively. No statistically significant differences were found between LBP group and control group. The mean ADC value of focal DWI lesions in early AS patients was （0. 899±0.265）×10^-3 mm2/s, which was significantly higher than that of adjacent normal-appearance areas （（0.454±0.079）×10^-3 mm2/s）. WB-DWl detected abnormalities in the 15 additional AS patients both within the sacroiliac joints and at other sites mean ADC value of focal DWl lesions of this patient （1.220±0.299） ×10^-3 mm2/s in the ilium. corresponding to the clinical symptoms of the patients. The cohort was （1.286±0.311）×10^-3 mm2/s in the sacrum and Conclusions Subchondral marrow ADC values of subchondral marrows near the sacroiliac joints allow for the differentiation of patients with early AS from normal volunteers and LBP patients. Combined with post-processing techniques such as MIP and MPR, WB-DWl allows for the comprehensive assessment of AS patients, an evaluation potentially helpful in determining prognosis and following the therapeutic response.

Monitoring the Progression of Renal Fibrosis by T2-weighted Signal Intensity and Diffusion Weighted Magnetic Resonance Imaging in Cisplatin induced Rat Models

Background：Diffusion weighted imaging （DWI）,with the applying of intravoxel incoherent motion model,has showed promising results in obtaining additional information about microperfusion and tubular flow associated with morphologic changes in chronic kidney diseases.The study aims to evaluate the potential of T2-weighted signal intensity （SI） and DWI with mono-and bi-exponential models to reflect the serial changes on cisplatin （CP） induced rat renal fibrosis models.Methods：Magnetic resonance exams were performed prior to and 2nd day,4th day,6th day,8th day,2nd week,3rd week and 4th week after CP injection at a 3.0T with an animal coil.Besides T2-weighted images （T2WI）,DWI of 13 b values from 0 to 1500 s/mm^2 was acquired.Apparent diffusion coefficient （ADC）,fluid fraction f,pure diffusivity D and pseudodiffusivity D＊ values were calculated.The regions of interest were placed on cortex （CO）,outer stripe of the outer medulla （OM） and inner stripe of the outer medulla （OM）,parameters were measured and compared among different time points.Five rats were scarified at each time point for pathological examination.Results：OM revealed remarkable hyperintense and broadened before it became an obscure thread,while CO demonstrated moderate hyperintense and IM didn＇t show significant change on T2WI.On all three stripes,ADC values decreased firstly then kept increasing since the 4th day;f values decreased on all stripes; D values had a tendency to increase with fluctuations but the changes didn＇t achieve statistical significance; D＊ values increased at the 2nd day then tended to be steady thereafter.Pathological findings revealed tubules epitheliums swelling followed by inflammation cells infiltration,interstitial fibrosis was observed since the 2nd week.Conclusions：All of T2-weighted SI,ADC,and biexponential models parameters vary during fibrotic process; biexponential model is superior to monoexponential model in separating changes of microperfusion together with tubular flow from pure diffusion.

Magnetic resonance diffusion-weighted imaging in the diagnosis of diffuse liver diseases in rats

Background The diagnosis of diffuse hepatic lesions in early stage is a tough task at any time for clinical conventional imaging. Magnetic resonance diffusion-weighted imaging (MR DWI) can detect the changes of tissue structure at molecular level. This study was designed to determine the value of DWI in the diagnosis of diffuse liver lesions in early stage. Methods Diffuse liver lesions were induced by diethylnitrosamine in 42 rats of test group. Fourteen rats in control group were fed with pure water. Dynamic changes of MR DWI were observed every week in both groups during the early stage of diffuse liver lesions (1 to 12 weeks after drug administration in the test group). Apparent diffusion coefficient (ADC) values of liver parenchyma in different stages and pathologic changes were analyzed. Results The process of diffuse hepatic lesions in the test group was classified into three stages according to pathological changes, namely hepatitis, hepatic fibrosis and cirrhosis. No obvious morphological changes were shown by conventional imaging in both groups during this stage. But MR DWI demonstrated heterogeneous signal changes in early stage of hepatic cirrhosis in the test group. No significant change of ADC values was found in the control group between different weeks ( P >0.05). The ADC values of the test group declined from the fifth week, and after the tenth week the ADC values were significantly different between the test and control groups at gradient factor (b) value 300 sec/mm 2 ( P <0.05). At b value 600 and 1000 sec/mm 2, significant difference was seen between the two groups from the sixth week onward. The range of ADC value of the groups was (1.7-0.9)±(0.40-0.04) mm 2/sec (b=600) and (1.38-0.75)±(0.07-0.35) mm 2/sec (b=1000), respectively. Dominant pathological changes included swelled hepatocytes within 1 to 4 weeks after the administration of diethylnitrosamine in the test group, hyperplasia of fibrous tissues in 5-8 weeks and formation of cirrhotic nodules in 9-12 weeks. Conclusions MR functional DWI could detect diffuse liver lesions earlier than conventional morphological imaging. ADC value as a marker for early diagnosis of diffuse liver lesions could also be used to inspect changes of the lesions