PURPOSE: Advances of magnetic resonance imaging (MRI), especially that of the Ultra-High Field (UHF) MRI will be reviewed. MATERIALS AND METHODS: Diffusion MRI data was obtained from a healthy adult young male of age 30 using a 7.0T research MRI scanner (Magnetom, Siemens) with 40 mT/m maximum gradient field. The specific imaging parameters used for the data acquisition were a single shot DW echo planar imaging. RESULTS: Three areas of the imaging experiments are focused on for the study, namely the anatomy, angiography, and tractography. CONCLUSION: It is envisioned that, in near future, there will be more 7.0T MRIs for brain research and explosive clinical application research will also be developed, for example in the area of connectomics in neuroscience and clinical neurology and neurosurgery.
Adult ; Angiography ; Brain ; Connectome ; Diffusion Magnetic Resonance Imaging ; Echo-Planar Imaging ; Humans ; Magnetic Resonance Imaging* ; Male ; Neurology ; Neurosciences ; Neurosurgery

OBJECTIVE: To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. MATERIALS AND METHODS: A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. RESULTS: The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p < 0.05). The sensitivity of the diagnostic performance was higher with an additional DWI in both 1.5T and 3T, but the sensitivities were similar with the addition of b values of 400 and 1000. The specificities of the diagnostic performances did not show significant differences (p value > 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. CONCLUSION: The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T.
Diffusion ; Echo-Planar Imaging ; Edema* ; Magnetic Resonance Imaging* ; Spine

PURPOSE: To determine changes in the signal intensity of intracerebral hemorrhagic lesions according to the time interval, between the onset of symptoms and MR imaging in the T1-weighted (T1W1), T2-weighted (T2W1) and diffusion-weighted modes. MATERIALS AND METHODS: Thirty-four patients with hemorrhagic stroke who underwent DWI and conventional MRI were involved in this study. Hemorrhagic phase was determined according to the time interval between the onset of symptoms and MR scanning, and was as follows: acute (3 days or less): eight patients); early subacute (7 days or less): ten patients; late subacute (4 weeks or less): seven patients; early chronic (3 months or less) : four patients); and late chronic (more than 3 months): five patients. Using a 1.5T MR imager and the single-shot echo-planar imaging technique, T1-weighted, fast spin-echo T2-weighted, and diffusion-weighted were obtained. In all cases qualitative signal intensity (SI) at the center of a lesion was recorded, and the ratio between this and normal brain parenchyma was calculated. RESULTS: SI at the center of a lesion was found to be iso or high/high/high (T1WI/T2WI/DWI) in five of eight acute-phase cases (interval of 24 hours or less) and low/low/low in the remaining three (interval of 72 hours or less). Other signal intensities were as follows: early subacute phase: high/low/low (all ten cases); late subacute phase: high/high/high (all seven cases); early chronic phase: high/high/high (all four cases); late chronic phase: low/high/low (all five cases). Mean SIRs were as follows: in the five acute-phase cases in which SI was iso or high: 1.42+/-0.78 / 2.58+/-0.84 / 1.35+/-0.08 (T1WI / T2WI / DWI); in the remaining three acute-phase cases: 0.94 +/-0.18 / 0.63+/-0.16 / 0.27+/-0.10; in the early subacute phase, 1.35+/-0.01 / 0.97+/-0.21 / 0.86+/-0.22 in early subacute phase, 1.58+/-0.04 / 1.54+/-0.09 / 1.44+/-0.14; in the early chronic phase: 1.26+/-0.11 / 1.06+/-0.14 / 0.97+/-0.12; and in the late chronic phase: 0.65+/-2.23 / 1.51+/-0.12 / 0.23+/-0.18. CONCLUSION: The DWI findings of intracerebral hemorrhage reflect the findings of T2WI. When interpreting the DWI findings in patients with intracerebral hemorrhage, an understanding of the temporal evolution of this is very helpful.
Brain ; Cerebral Hemorrhage ; Diffusion* ; Echo-Planar Imaging ; Humans ; Intracranial Hemorrhages* ; Magnetic Resonance Imaging ; Stroke

PURPOSE: To evaluate the usefulness of apparent diffusion coefficient (ADC) values using diffusion-weighted magnetic resonance imaging (DWI) in patients with ovarian cystic tumors. MATERIALS AND METHODS: During past 12 months, we studied 30 patients who were clinically suspected of having ovarian cystic tumors and who underwent DWI using a 1.5 T MR unit. Eight patients with small cystic ovarian lesions of less than 3 cm in diameter and insufficient DWI were excluded from the calculation of the ADC values. The remaining twenty-six cystic ovarian lesions in 22 patients were classified into four groups; ovarian cysts, cystadenomas, other benign tumors, and malignant tumors. DWI was obtained using single-shot spin echo planar imaging and two gradient steps (b values of 0, 800 sec/mm2). The ADC values were measured using regions-of-interest (ROI) in the cystic components of the DWI located in the same section as the T2-weighted image and away from the septation and solid components. RESULTS: The mean ADC values were 0.196+/-0.105x10(-3) mm2/sec in the ovarian cysts, 1.312+/-1.064x10(-3) mm2/sec in the cystadenomas, 0.274+/-0.124x10(-3) mm2/sec in the other benign tumors, and 1.011+/-0.080x10(-3) mm2/sec in the malignant tumors. The differences in the ADC values between the ovarian cysts and cystadenomas, the ovarian cysts and malignant tumors, the cystadenomas and other benign tumors, and the other benign tumors and malignant tumors were statistically significant (p < 0.01). There was no statistically significant difference in the ADC values between the ovarian cysts and other benign tumors, or between the cystadenomas and malignant tumors (p > 0.05). CONCLUSION: The calculated ADC values using DWI should be helpful in the differential diagnosis of cystic ovarian tumors.
Cystadenoma ; Diagnosis, Differential ; Diffusion* ; Echo-Planar Imaging ; Female ; Humans ; Magnetic Resonance Imaging* ; Ovarian Cysts* ; Ovary

PURPOSE: To assess the usefulness of diffusion-weighted MR imaging (DWI) and apparent diffusion coefficient (ADC) in the initial and follow-up studies of patients with neuro-Behcet's disease. MATERIALS AND METHODS: Six patients diagnosed with neuro-Behcet's disease were the subjects of this study. Initial and follow-up MR imaging were obtained in all six patients. Initial and follow-up DWI were also obtained in four of the six patients, with only an initial DWI in the other two. The DWI were obtained using multi-shot echo planar imaging, on a 1.5T MR unit, with two gradient steps (b values of 0, 1000 sec/mm2). The ADC value and ADC maps were obtained using commercial software. The locations and signal intensities of the lesions were analyzed on conventional MRI and DWI, respectively. The ADC values of the lesions were calculated on the initial and follow-up DWI, and compared those of lesions in the normal contralateral regions. RESULTS:The initial DWI showed iso-signal intensities in four of the six patients, with high signal intensities in the other two. In five of the six patients, including three of the four that showed isosignal intensities and the two that showed high signal intensities on the initial DWI, the ADC values of the involved lesions were higher than those of the normal contralateral regions. In three of four that showed isosignal intensities, the ADC values of the lesions were decreased and normalized on the follow-up DWI. CONCLUSION: Obtaining DWI and ADC values in patients with neuro-Behcet's disease may be helpful in the understanding of pathophysiology and differential diagnosis of this disease.
Diagnosis, Differential ; Diffusion ; Echo-Planar Imaging ; Follow-Up Studies* ; Humans ; Magnetic Resonance Imaging*

OBJECTIVE: To compare the diagnostic performance of readout-segmented echo-planar imaging (RS-EPI)-based diffusion kurtosis imaging (DKI) and that of diffusion-weighted imaging (DWI) for differentiating malignant from benign masses in head and neck region. MATERIALS AND METHODS: Between December 2014 and April 2016, we retrospectively enrolled 72 consecutive patients with head and neck masses who had undergone RS-EPI-based DKI scan (b value of 0, 500, 1000, and 1500 s/mm2) for pretreatment evaluation. Imaging data were post-processed by using monoexponential and diffusion kurtosis (DK) model for quantitation of apparent diffusion coefficient (ADC), apparent diffusion for Gaussian distribution (Dapp), and apparent kurtosis coefficient (Kapp). Unpaired t test and Mann-Whitney U test were used to compare differences of quantitative parameters between malignant and benign groups. Receiver operating characteristic curve analyses were performed to determine and compare the diagnostic ability of quantitative parameters in predicting malignancy. RESULTS: Malignant group demonstrated significantly lower ADC (0.754 ± 0.167 vs. 1.222 ± 0.420, p < 0.001) and Dapp (1.029 ± 0.226 vs. 1.640 ± 0.445, p < 0.001) while higher Kapp (1.344 ± 0.309 vs. 0.715 ± 0.249, p < 0.001) than benign group. Using a combination of Dapp and Kapp as diagnostic index, significantly better differentiating performance was achieved than using ADC alone (area under curve: 0.956 vs. 0.876, p = 0.042). CONCLUSION: Compared to DWI, DKI could provide additional data related to tumor heterogeneity with significantly better differentiating performance. Its derived quantitative metrics could serve as a promising imaging biomarker for differentiating malignant from benign masses in head and neck region.
Diffusion* ; Echo-Planar Imaging ; Head* ; Humans ; Magnetic Resonance Imaging ; Neck* ; Population Characteristics ; Retrospective Studies ; ROC Curve

PURPOSE: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. MATERIALS AND METHODS: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. RESULTS: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. CONCLUSIONS: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.
Magnetic Resonance Imaging, Cine*

An echo planar imaging (EPI)-based spin-echo sequence is often used to obtain diffusion tensor imaging (DTI) data on most of the clinical MRI systems. However, this sequence is confounded with the susceptibility artifacts, especially on the temporal lobe in the human brain. Therefore, the objective of this study was to design a pulse sequence that relatively immunizes the susceptibility artifacts, but can map diffusion tensor components in a single-shot mode. A multi-slice multi-echo pulsed-gradient spin-echo (MePGSE) sequence with eight echoes wasdeveloped with selective refocusing pulses for all slices to map the full tensor. The first seven echoes in the train were diffusion-weighted allowing for the observation of diffusion in several different directions in a single experiment and the last echo was for crusher of the residual magnetization. All components of diffusion tensor were measured by a single shot experiment. The sequence was applied in diffusive phantoms. The preliminary experimental verification of the sequence was illustrated by measuring the apparent diffusion coefficient (ADC) for tap water and by measuring diffusion tensor components for watermelon. The ADC values in the series of the water phantom were reliable. The MePGSE sequence, therefore, may be useful in human brain studies.
Artifacts ; Brain ; Citrullus ; Diffusion Tensor Imaging* ; Diffusion* ; Echo-Planar Imaging ; Humans ; Magnetic Resonance Imaging* ; Temporal Lobe ; Water

PURPOSE: To evaluate the clinical usefulness of diffusion weighted MR imaging(DWI) in the differential diagnosis of brain tumors. MATERIALS AND METHODS: DWI and conventional MR images of nineteen patients with brain tumors(10 metastatic tumors, 4 high grade gliomas , 4 low grade astrocytomas, one oligodendroglioma)were obtained on 1.5T unit. DWI was obtained using single shot spin echo planar imaging with b-value near 1000. We analyzed the signal intensities of lesions including solid portion, necrotic or cystic portion and peritumoral edema of brain tumors (classified five grades comparison with the signal intensities of brain parenchyma and CSF)and calculate the SIR(signal intensity ratio)of lesions to the contralateral normal brain parenchyma. We analyzed statistically the signal intensities and SIR of tumors using independence T test. RESULTS: In solid portions of tumors, all the metastatic tumors and high grade gliomas showed high signal intensities, but low grade astrocytomas and oligodendroglioma showed iso or slight high signal intensities to the normal brain parenchyma. The SIR of solid portion has positive correlation with malignant potential(metastatic tumors 1.52, high grade gliomas 1.38, low grade astrocytomas 1.16, oligodendroglioma 1.31)(p<0.05). In peritumoral edema where seen in 14 tumors, seven of 10 metastatic tumors and two of 4 high grade gliomas showed iso signal intensities, whereas edemas in other 5 brain tumors showed hyperintense to the normal brain parenchyma. The SIRs of peritumoral edemas in metastatic tumors(1.14) was lower than high grade gliomas(1.31),but statistically insignificant. The SIR of cystic or necrotic portion of brain tumors was 0.63. In non enhancing solid portions, three of six cases showed hyperintense to the adjacent peritumoral edema. CONCLUSION: On DWI, the signal intensities of solid portion has positive correlation with malignant potential, and perilesional edema of brain tumors appear various signal intensities owing to "T2 shine through effect" and the extensiveness of vasogenic edema. Another merit using DWI on the evaluation of brain tumors is to improved better delineation of tumor margins from the adjacent edemas, especially at the non enhancing solid portion of the tumors.
Astrocytoma ; Brain Neoplasms* ; Brain* ; Diagnosis, Differential ; Diffusion ; Echo-Planar Imaging ; Edema ; Glioma ; Humans ; Magnetic Resonance Imaging* ; Oligodendroglioma

OBJECTIVE: To compare apparent diffusion coefficients (ADCs) of brain segments by using two diffusion-weighted imaging acquisition modes, single-shot echo-planar imaging (ss-EPI) and read-out-segmented echo-planar imaging (rs-EPI), and to assess their correlation and agreement in healthy controls. MATERIALS AND METHODS: T2-weighted (T2W) images, rs-EPI, and ss-EPI of 30 healthy subjects were acquired using a 3T magnetic resonance scanner. The T2W images were co-registered to the rs-EPI and ss-EPI, which were then segmented into the gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) to generate masking templates. ADC maps of rs-EPI and ss-EPI were also segmented into the GM, WM, and CSF by using the generated templates. ADCs of rs-EPI and ss-EPI were compared using Student's t tests and correlated using Pearson's correlation coefficients. Bland-Altman plots were used to assess the agreement between acquisitions.
Brain ; Cerebrospinal Fluid ; Diffusion ; Echo-Planar Imaging ; Gray Matter ; Healthy Volunteers ; Magnetic Resonance Imaging ; Masks ; White Matter