Objective To analyze the correlation and difference of axial length (AL) measurements by comparing magnetic resonance imaging (MRI) of different pulse sequence with IOL Master of normal eyes. Methods The 67 emmetropic volunteers were selected by the slit lamp microscope, direct ophthalmoscope and refractive examination in this study. The patients included 30 males and 37 females. The patientsprime; ages ranged from eight to 21 years, with a mean age of 14.9 years. Fast spin echo (FSE) T1WI, FSE T2WI, fluid attenuated inversion recovery (FLAIR) T2WI, FSPGR T1WI were performed. The axial (AX) and oblique sagittal (OS) sections were taken and the AL from MRI section with different sequences were measured. The AL taken by IOL-Master was used as standard. The difference and correlation between measurements of two methods were analyzed. Results The AL of AX FSE T1WI, AX FSE T2WI, AX FLAIR T2WI, AX FSPGR T1WI, OS FSE T1WI, OS FSE T2WI, OS FLAIRT2WI and OS FSPGR T1WI were (24.14plusmn;0.81), (24.26plusmn;0.81), (23.87plusmn;0.79), (24.11plusmn;0.82), (24.08plusmn;0.86), (24.22plusmn;0.81), (23.84plusmn;0.79) and (24.03plusmn;0.81) mm, respectively. The AL of IOLMaster was (23.91plusmn;0.80) mm. The differences of AL between IOL-Master and various MRI sequences were statistically significant (t=－13.54,－23.20, 4.08, －15.55, －8.00, －23.22, 5.25, －10.62;P＜0.01). There were excellent correlations between IOL-Master and various MRI sequences (r=0.97, 0.96, 0.98, 0.97, 0.96, 0.80, 0.98, 0.97;P＜0.01). Conclusion There are differences and significant correlations between MRI sequences and IOL-Master.
Objective To investigate the value of magnetic resonance (MR) imaging for diagnosing typeⅠ congenital choledochocele and its complications. Methods The MR imaging data of 13 cases with proved typeⅠ congenital choledochocele associated with complications were retrospectively reviewed and compared with operative findings. MR imaging sequences included axial T2W and T1W plain scan, true-FISP coronal images, 2D-MRCP, and Gd-enhanced T1W images. Results All patients had cystic dilatation of the common bile ducts to various degrees. In 6 patients complicated with stone and infection, the bile duct showed uniform wall thickening with marked enhancement, and calculus were depicted within the duct lumen with dilatation of the proximal biliary duct. In 7 cases complicated with carcinoma of biliary duct, a polypoid soft tissue mass or nodule was seen inside the ductal lumen in 3 cases, or the duct wall was irregularly thickened in 4 patients. Six cases received curative operation, but one patient with extensive local infiltration, vascular encasement and lymphadenopathy had only palliative treatment. MR imaging observations were verified by surgery findings in all 13 patients.Conclusion MR imaging is very valuable not only in diagnosing typeⅠ congenital choledochocele, but also in revealing its complications.
Objective To assess value and limitations of non-invasive methods in assessing liver fibrosis．Methods By summarized current situation and advancement of serum fibrotic markers, ultrasound, CT and MRI in assessing liver fibrosis, we investigated their value and limitations. Results In addition to diagnosis, non-invasive methods of assessing liver fibrosis assess severity of liver fibrosis. For liver fibrosis, however, non-invasive methods can not monitor effectively reaction to therapy and progression. Conclusion Non-invasive methods play important roles in diagnosis and assessing severity of liver fibrosis, and reduce the need of liver biopsy.
Magnetic resonance imaging (MRI) is an important medical imaging method, whose major limitation is its long scan time due to the imaging mechanism, increasing patients’ cost and waiting time for the examination. Currently, parallel imaging (PI) and compress sensing (CS) together with other reconstruction technologies have been proposed to accelerate image acquisition. However, the image quality of PI and CS depends on the image reconstruction algorithms, which is far from satisfying in respect to both the image quality and the reconstruction speed. In recent years, image reconstruction based on generative adversarial network (GAN) has become a research hotspot in the field of magnetic resonance imaging because of its excellent performance. In this review, we summarized the recent development of application of GAN in MRI reconstruction in both single- and multi-modality acceleration, hoping to provide a useful reference for interested researchers. In addition, we analyzed the characteristics and limitations of existing technologies and forecasted some development trends in this field.
Objective To investigate the application of the dynamic contrast enhanced MRI (DCE-MRI ) combined with magnetic resonance spectroscopy (MRS) in the diagnosis of prostate cancer. Method A total of 60 patients with prostate cancer and 60 patients with benign prostatic hyperplasia diagnoses in Sichuan Cancer Hospital from January 2011 to January 2014 were included as prostate cancer group and proliferative group respectively. Sixty healthy individuals during the same period were included as the control group. We used Siemens Avanto 1.5 T high field superconducting MRI for DCE-MRI scan and MRS scan. After the MRS scan was finished, we used the workstation spectroscopy tab spectral analysis. Eventually we got the crest lines of prostate metabolites choline (Cho), creatine (Cr) and citrate (Cit). Then we calculated Cho/Cit, (Cho+Cr)/Cit and their average. Results Comparing the signal value in 21 seconds, 1 minute, 2 minutes of DCE-MRI, the differences among the three groups were statistically significant (P<0.05). Comparing the results of spectral analysis, the differences among the three groups were statistically significant (P<0.05). The sensitivity was 89.67%, the specificity was 95.45% and the accuracy was 94.34% when using DCE-MRI combined with MRS. Conclusion DCE-MRI combined with MRS greatly improves the sensitivity, specificity and accuracy of the diagnosis of prostate cancer; it has a great application value in the diagnosis of prostate cancer.
Solitary pulmonary nodule (SPN) is defined as a rounded opacity≤3 cm in diameter surrounded by lung parenchyma. The majority of smokers who undergo thin-section CT have SPNs, most of which are smaller than 7 mm. In the past, multiple follow-up examinations over a two-year period, including CT follow-up at 3, 6, 12, 18, and 24 months, were recommended when such nodules are detected incidentally. This policy increases radiation burden for the affected population. Nodule features such as shape, edge characteristics, cavitation, and location have not yet been found to be accurate for distinguishing benign from malignant nodules. When SPN is considered to be indeterminate in the initial exam, the risk factor of the patients should be evaluated, which includes patients' age and smoking history. The 2005 Fleischner Society guideline stated that at least 99% of all nodules 4 mm or smaller are benign; when nodule is 5-9 mm in diameter, the best strategy is surveillance. The timing of these control examinations varies according to the nodule size (4-6, or 6-8 mm) and the type of patients, specifically at low or high risk of malignancy concerned. Noncalcified nodules larger than 8 mm diameter bear a substantial risk of malignancy, additional options such as contrast material-enhanced CT, positron emission tomography (PET), percutaneous needle biopsy, and thoracoscopic resection or videoassisted thoracoscopic resection should be considered.
ObjectiveTo compare the effectiveness of T2 weighted image (T2WI) and some compounded MRI techniques, including T2WI combined with magnetic resonance spectroscopy (T2WI+MRS), T2WI combined with diffusion weighted imaging (T2WI+DWI) and T2WI combined with dynamic contrast-enhancement [T2WI+(DCE-MRI)] respectively, with 1.5 T MR scanner in diagnosing prostate cancer through a blinding method. MethodsBetween March 2011 and April 2013, two observers diagnosed 59 cases with a blinding method. The research direction of radiologist A was to diagnose prostate cancer. The observers diagnosed and scored the cases with T2WI, T2WI+(DCE-MRI), T2WI+MRS, T2WI+DWI and compositive method respectively. The data were statistically analyzed with receiver operating characteristic (ROC) curve. ResultsAccording to the ROC curve, both observers got the sequence of area under curve (AUC) as T2WI+DWI > T2WI+(DCE-MRI) > T2WI+MRS > T2WI. On the basis of the result from observer A, the AUC from each technique was similar. The AUC of T2+DWI was slightly bigger than others. The specificity of single T2WI was the lowest; the sensitivity of T2WI was slightly higher. The AUC of the compositive method was marginally larger than T2WI+DWI. According to the result from observer B, the AUC of T2WI+DWI was obviously larger than the others. The AUC of single T2WI was much smaller than the other techniques. The single T2WI method had the lowest sensitivity and the highest specificity. The AUC of T2WI+DWI was slightly larger than the compositive method. The AUC of T2WI+(DCE-MRI), T2WI+MRS, single T2WI methods from observer A was obviously higher than those from the score of observer B. The AUC of T2WI+DWI from the two observers was similar. ConclusionThe method of combined T2WI and functional imaging sequences can improve the diagnosing specificity when a 1.5 T MR scanner is used. T2WI+DWI is the best method in diagnosing prostate cancer with least influence from the experience of observers in this research. The compositive method can improve the diagnosis of prostate cancer effectively, but when there are contradictions between different methods, the T2WI+DWI should be considered as a key factor.
Objective To observe the results of function MRI and perimetry in patients with visual pathway diseases.Methods Three patients (6 eyes) with pituitary adenoma and craniopharyngioma diagnosed via pathological examination and three healthy volunteers aged from 24 to 30 were collected. The best corrected visual acuity was nonlight perception1.0 in the 6 sick eyes and 1.0 in the healthy eyes; all the involved individuals had no other ocular diseases except myopia and without any contraindications of MRI. Common tests including the best visual acuity, fundus test by direct or indirect ophthalmoscope, center static visual field tested by Octopus 101 perimeter, program 32, tendency oriented perimetry were performed. The visual stimulation subtended a field of view of about 12 degrees，consisted of high contrast and drifting checkerboards. MRI parameters: GE signa VH/i 30T scanner. Functional data: GRE-EPI sequence，20 slices lying perpendicular to the calcarine sulcus. Anatomical data was obtained using 3DSPGR sequence to acquire high resolution. The cortical surface was unfolded and then cut and inflated. Functional data was presented to the inflated surface and subsequently analyzed by AFNI software.Results In six eyes, three had temporal defects, two had upper temporal visual field defects, and the other one did not finish the visual field test. The retinotopic representations of health adults were obtained by using the phaseencoded visual stimulation. The Eccentricity coordinate maps showed that foveal representations lay in the occipital poles and the representations appeared further anterior as eccentricity increased. The polar angle coordinate maps showed that early retinotopically organized areas had a representation of visual field. The visual cortex beneath the calcarine sulcus matched with the upper visual field of the opposite side and which upon the calcarine sulcus matched with the under visual field of the opposite side. Less or no visual cortex response was revealed in the patients′ function MRI or the response in injury side was vanished. The visual cortex response related with the visual field defects could not be induced in function MRI.Conclusion There is a good correlation between function MRI data and the results of perimetric evaluation. The function MRI can show the visual cortex response correlated with the visual field defects of the patients with visual pathway diseases.
Objective To review the current status of magnetic resonance imaging (MRI) techniques in the evaluation of hepatic fibrosis. Methods The application and recent advances of various kinds of MRI techniques in evaluating hepatic fibrosis were summarized by literature review. Results The state-of-the-art of MRI evaluating of hepatic fibrosis included common contrast-enhanced MRI, double contrast-enhanced MRI, and various functional MRI techniques. Common contrast-enhanced MRI could detect morphological changes of the liver, but little value in phasing. Double contrast-enhanced MRI markedly increased the contrast to noise ratio. Except diagnosis liver fibrosis, functional MRI also could phase it by its serverity. Conclusion MRI techniques, especially those functional MRI techniques, are advancing very fast and have very great potentiality in both the diagnosis and severity assessment of hepatic fibrosis.
ObjectiveTo investigate the diagnostic value of MRI hip joint unilateral oblique coronary scanning in the diagnosis of femoroacetabular impingement (FAI).MethodsFrom February to October 2014, 75 patients with hip joint pain who were highly suspected of FAI after X-ray or CT examination were selected as subjects. Using Siemens 1.5 T MR, fat-suppressed T2-weighted imaging sequences, T1-weighted imaging sequences, and proton density-weighted imaging sequences were used. For each patient two scan methods were used. Method A: on the sagittal image of the hip joint, the line of sight was parallel to the oblique coronal plane scan of the (one-sided) long axis of the femoral neck. Method B: on the cross-sectional image of the hip joint, the positioning line was parallel to the conventional hip joint coronal scan of the left and right femoral heads. McNemar test was used to compare the detection rates of FAI of the two methods.ResultThe detection rate of FAI of A-scanning [62.6% (47/75)] was higher than that of B-scanning [30.6% (23/75)], and the difference was statistically significant (P<0.001).ConclusionAn image obtained from a diagonal coronal scan parallel to the long axis of the femoral neck can more fully display the pathological changes of the acetabular labrum and the anatomy of the femoral head and neck joints, and the damage of the femoral head and neck junction, which provides a more reliable imaging basis for the clinician to diagnose FAI.