The accurate diagnosis and staging of hepatic fibrosis is crucial for treatment and prognosis of liver disease. The current gold standard is liver biopsy, but it cannot be used in population-based screening, and has well known drawbacks if used for monitoring of disease progression or treatment results. Functional MR, as a non-invasive method, is increasingly used in hepatic fibrosis and became the current hot spot. Most recently available functional MR imaging techniques including diffusion weighted imaging, perfusion weighted imaging and MR spectroscopy can detect cirrhosis or fibrosis reasonably accurately. However, to date only MR elastography has been able to stage fibrosis or diagnose mild disease. MR diffusion weighted appears next most promising.
Diffusion Magnetic Resonance Imaging ; Humans ; Liver Cirrhosis ; classification ; diagnosis ; Magnetic Resonance Imaging ; methods ; Magnetic Resonance Spectroscopy

OBJECTIVETo elaborate the role of quantitative magnetic resonance imaging (MRI) parameters in the evaluation of treatment response in malignant tumors.

DATA SOURCESData cited in this review were obtained mainly from PubMed in English from 1999 to 2014, with keywords "dynamic contrast-enhanced (DCE)-MRI," "diffusion-weighted imaging (DWI)," "microcirculation," "apparent diffusion coefficient (ADC)," "treatment response" and "oncology."

STUDY SELECTIONArticles regarding principles of DCE-MRI, principles of DWI, clinical applications as well as opportunity and aspiration were identified, retrieved and reviewed.

RESULTSA significant correlation between ADC values and treatment response was reported in most DWI studies. Most quantitative DCE-MRI studies showed a significant correlation between K trans values and treatment response. However, in different tumors and studies, both high and low pretreatment ADC or K trans values were found to be associated with response rate. Both DCE-MRI and DWI demonstrated changes in their parameters hours to days after treatment, showing a decrease in K trans or an increase in ADC associated with response in most cases.

CONCLUSIONSCombinations of quantitative MRI play an important role in the evaluation of treatment response of malignant tumors and hold promise for use as a cancer treatment response biomarker. However, validation is hampered by the lack of reproducibility and standardization. MRI acquisition protocols and quantitative image analysis approaches should be properly addressed prior to further testing the clinical use of quantitative MRI parameters in the assessment of treatments.

OBJECTIVE: We wanted to evaluate the effect of the number of diffusion-sensitizing gradient directions on the image quality for evaluating myocardial anisotropy and fiber tracking by using in vitro diffusion tensor MR imaging (DT-MRI). MATERIALS AND METHODS: The DT-MR images, using a SENSE-based echoplanar imaging technique, were acquired from ten excised porcine hearts by using a 3T MR scanner. With a b-value of 800 s/mm2, the diffusion tensor images were obtained for 6, 15 and 32 diffusion-sensitizing gradient directions at the midventricular level. The number of tracked fibers, the fractional anisotropy (FA), and the length of the tracked fibers were measured for the quantitative analysis. Two radiologists assessed the image quality of the fiber tractography for the qualitative analysis. RESULTS: By increasing the number of diffusion-sensitizing gradient directions from 6 to 15, and then to 32, the FA and standard deviation were significantly reduced (p < 0.01), and the number of tracked fibers and the length of the tracked fibers were significantly increased (p < 0.01). The image quality of the fiber tractography was significantly increased with the increased number of diffusion-sensitizing gradient directions (p < 0.01). CONCLUSION: The image quality of in vitro DT-MRI is significantly improved as the number of diffusion-sensitizing gradient directions is increased.
Animals ; Anisotropy ; Diffusion Magnetic Resonance Imaging/*methods ; Myocardium/*cytology ; Swine

No abstract available.
Diffusion Magnetic Resonance Imaging/*methods ; Humans ; Male ; Prostatic Neoplasms/*diagnosis

OBJECTIVETo explore the methodology as well as the features, quantificational index, and reference standard of 3.0 Tesla magnetic resonance (MR) diffusion-weighted imaging (DWI) on the normal rabbit's liver.

METHODSTwenty New Zealand white rabbits were enrolled and DWI was performed after anesthetics with multi-b values at 3.0 T MR scanner. Apparent diffusion coefficient (ADC) values as well as the difference between maximum and minimum ADC values, signal strength (SH), noise signal (SD), signal to noise ratio (SNR), and quality index (QI) were recorded and analyzed.

RESULTSWith b value increased, the ADC values decreased accordingly (P < 0.001). The difference between maximum and minimum ADC values with b = 1000 s/mm2 was the least (good stability), b = 600 s/mm2 was the second least, and b = 300 s/mm2 was greatest (bad stability). The SH decreased at the same time (P < 0.001), but the difference among DWI with b =600, 800, and 1000 s/mm2 was not statistically significant (P > 0.05). The SD decreased at the same time (P < 0.001), but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm2 was not statistically significant (P > 0.05). The SNR decreased at the same time (P < 0.001), but there were no significant differences between DWI with b = 600 s/mm2 and b = 800 s/mm2 or b = 600 s/mm2 and b = 1000 s/mm2 (P > 0.05). The SNR of DWI with b = 800 s/mm2 and b = 1000 s/mm2 was lower. The QI decreased at the same time (P < 0. 001) , but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm was not statistically significant (P > 0.05).

CONCLUSIONWhen 3.0 T MR DWI is applied for rabbit liver, it is better to use b = 600 s/mm2 for reducing scanning time and assuring better diffusion weights, quantity of images, and stability of ADC measurement.

Magnetic resonance imaging has became the major method for rectal cancer diagnosis. As a novel magnetic resonance functional imaging technique, diffusion-weighted imaging has improved the lesion detection sensitivity and provided more information on changes in body functions. The past two decades have witnessed the increasing application of this technique in clinical practices. This article summarizes the application of diffusion weighted imaging in rectal cancer diagnosis.
Diffusion Magnetic Resonance Imaging ; methods ; Humans ; Rectal Neoplasms ; diagnosis

With the capability of measuring the water molecular diffusion qualitatively and quantitatively, diffusion weighted imaging (DWI) is currently the optimal and the only magnetic resonance method to observe water molecular diffusion motion in living tissues. Along with the advances in magnetic resonance technology, particularly the development of fast imaging sequences, DWI has been widely used in the imaging of liver, pancreas, kidneys and other solid organs. In recent years, DWI has been applied in the stomach. This article summarizes recent research on the application of DWI for the diagnosis and treatment of gastric cancer.
Diffusion Magnetic Resonance Imaging ; methods ; Humans ; Stomach Neoplasms ; diagnosis ; therapy

BACKGROUND AND OBJECTIVES: This study was to done to determine the value of PROPELLER diffusion-weighted imaging in detecting cholesteatoma. SUBJECTS AND METHOD: Sixty-five patients were evaluated by preoperative magnetic resonance imaging (MRI) with PROPELLER diffusion-weighted imaging. Of 65 patients, 16 patients had chronic otitis media without cholesteatoma and 49 patients with cholesteatoma. Surgical and pathologic findings were compared with the preoperative findings by PROPELLER diffusion-weighted imaging to assess the sensitivity, specificity, positive and negative predictive values. RESULTS: In 49 patients with cholesteatoma, high signal intensity compatible with cholesteatoma was found in 46 patients, whereas in 16 patients without cholesteatoma, high signal intensity was not detected in any of them. The sensitivity, specificity, positive and negative predictive values for PROPELLER diffusion-weighted imaging were 94.1%, 100%, 100%, and 84.2%, respectively. CONCLUSION: PROPELLER diffusion-weighted imaging can be a useful tool in detecting cholesteatoma.
Cholesteatoma* ; Diffusion Magnetic Resonance Imaging ; Humans ; Magnetic Resonance Imaging ; Methods ; Otitis Media ; Sensitivity and Specificity

In this paper, the MRI manifestations of 15 patients with benzene toxic encephalopathy were analyzed, and the lesion location, shape, scope and signal were observed. The clinical manifestations of 15 patients were mainly central nervous system damage, and the MRI manifestations were characteristic, with a wide range of lesions, and the shapes were "sunflower-like", "flame-like", "bracket-like" and "butterfly-like", and the MRI signal was sheet-like long T(1), long T(2), fluid attenuated inversion recovery (FLAIR) sequence and diffusion weighted imaging (DWI) high signal, apparent diffusion coeffecient (ADC) map low, equal or high signals. When the patient's diagnosis is unclear, MRI examination may provide clinical basis for diagnosis.
Benzene ; Diffusion Magnetic Resonance Imaging/methods* ; Humans ; Magnetic Resonance Imaging ; Neurotoxicity Syndromes/etiology*

Diffusion time and diffusion gradient magnetic strength are two important parameters of the pulsed gradient spin echo (PGSE) that is the most commonly used method in diffusion-weighted magnetic resonance imaging. However, the effects of the diffusion time on the apparent diffusion coefficient (ADC) in previous studies are controversial, and the effects of the diffusion gradient magnetic strength have received little attention. In this study, a new experimental protocol was designed to evaluate the effects of the two parameters on ADC. It was found that ADC decreased significantly with the increase of diffusion time or increase of diffusion gradient magnetic strength, which cannot be explained by the previous theories. Through theoretical analysis, we found the flaw of PGSE method, which is on explanation for the controversial results of diffusion time in former literatures.
Diffusion ; Diffusion Magnetic Resonance Imaging ; methods ; Electromagnetic Fields ; Image Processing, Computer-Assisted ; methods ; Water ; chemistry