Acceleration of ASL-based time-resolved MR angiography by acquisition of control and labeled images in the same shot (ACTRESS).

PURPOSE: Noncontrast 4D-MR-angiography (MRA) using arterial spin labeling (ASL) is beneficial because high spatial and temporal resolution can be achieved. However, ASL requires acquisition of labeled and control images for each phase. The purpose of this study is to present a new accelerated 4D-MRA approach that requires only a single control acquisition, achieving similar image quality in approximately half the scan time. METHODS: In a multi-phase Look-Locker sequence, the first phase was used as the control image and the labeling pulse was applied before the second phase. By acquiring the control and labeled images within a single Look-Locker cycle, 4D-MRA was generated in nearly half the scan time of conventional ASL. However, this approach potentially could be more sensitive to off-resonance and magnetization transfer (MT) effects. To counter this, careful optimizations of the labeling pulse were performed by Bloch simulations. In in-vivo studies arterial visualization was compared between the new and conventional ASL approaches. RESULTS: Optimization of the labeling pulse successfully minimized off-resonance effects. Qualitative assessment showed that residual MT effects did not degrade visualization of the peripheral arteries. CONCLUSION: This study demonstrated that the proposed approach achieved similar image quality as conventional ASL-MRA approaches in just over half the scan time. Magn Reson Med 79:224-233, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

[Clinical findings and macular lesions in basal laminar drusen].

PURPOSE: To investigate the clinical characteristics and accompanying macular lesions in Japanese patients with basal laminar drusen (BLD). DESIGN: Retrospective cross-sectional study. PATIENTS AND METHODS: Fifty four eyes of 27 Japanese patients with BLD were examined for the clinical characteristics of BLD and accompanying macular lesions using retro-mode imaging (Scanning Laser Ophthalmoscope F-10, Nidek) in addition to current methods such as fluorescein angiography (FA), indocyanine green angiography (IA), fundus autofluorescence (FAF) and spectral domain optical coherence tomography (SD-OCT). RESULTS: 1)BLD was more clearly identified using retro-mode imaging than any of the other current imaging methods, and was divided into two types: a crater type (relatively sparsely distributed BLD with many soft drusens) and a mesh type (uniformly distributed BLD). 2) BLD in both eyes was more common in female patients, and had the same type, distribution and similar macular lesions in both eyes. 3) Among the macular lesions, we observed macular atrophy, retinal angiomatous proliferation and vitelliform detachment in many patients, in contrast to few cases of choroidal neovascularization and no polypoidal choroidal vasculopathy. CONCLUSIONS: BLD may be regarded as a disease that is different from age-related macular degeneration (AMD).

[Problem of spectral attenuated with inversion recovery fat suppression method with respiratory-gated].

The purpose of this study was to investigate the effect of fat suppression when we use respiratory-gated spectral attenuated with inversion recovery (SPAIR) method with respiratory-gated. We experimented on phantom and in-vivo study using simulated wave of respiratory-gated SPAIR at 1.5 tesla and 3.0 tesla. As a result, the effect of fat suppression becomes wrong with longer intervals of inspiration and expiration by wave of respiratory-gated. The signal intensity also varies with each slice. This result had the same trend on phantom and in-vivo study. The longitudinal magnetization of fat becomes a stable state when SPAIR pulse is shot more than once. However, the SPAIR method with respiratory-gated collect signal before the longitudinal magnetization of fat to be stable state, and fat suppression effect becomes bad, because the inversion time does not match the null point of the fat. Therefore, when we use SPAIR method with respiratory-gated it always causes bad fat suppression.

[Detection for retinal pigment epithelial lesions in fellow eye of age-related macular degeneration by retro-mode].

PURPOSE: Using the Retro-mode (RM), to detect drusen and other minute lesions of the retinal pigment epithelium (RPE) invisible in current imaging methods in the fellow eye of Japanese patients with exudative age-related macular degeneration(AMD). DESIGN: A retrospective cross-sectional study. PATIENTS AND METHODS: The fellow eyes of nineteen Japanese patients with unilateral exudative AMD were examined using RM imaging (F-10 fundus camera, Nidek), in contrast with fluorescein angiography, indocyanine green angiography, and optic coherence tomography (3D OCT-1000, Topcon Co). We were able to identify the type of drusen and minute granular lesions (MGLs) in the RPE. RESULTS: In all patients, RM imaging gave easier to identify images of all types of drusen than other current imaging methods. Moreover, MGLs of the RPE either adjacent to drusen or without drusen, invisible in other current methods, were detected by RM imaging. CONCLUSIONS: The RM provides clearer imaging of all kind of drusen, and MGLs of the RPE invisible with current methods. These MGLs are possible precursors of drusen.

Temperature measurement of intracranial cerebrospinal fluid using second-order motion compensation diffusion tensor imaging.

To reduce the determination errors of CSF pulsation in diffusion-weighted image (DWI) thermometry, we investigated whether applying second-order motion compensation diffusion tensor imaging (2nd-MC DTI) and fractional anisotropy (FA) processing improves the measurement of intracranial cerebrospinal fluid (CSF) temperature. In a phantom study, we investigated the relationship between temperature and FA in artificial CSF (ACSF) to determine the threshold for FA processing. The calculated temperatures of ACSF were compared with those of water. In a human study, 18 healthy volunteers were scanned using conventional DTI (c-DTI) and 2nd-MC DTI on a 3.0 T magnetic resonance imaging (MRI) system. A temperature map was created using diffusion coefficients from each DWI with/without FA processing. The temperatures of intracranial CSF were compared between each DTI image using Welch's analysis of variance and Games-Howell's multiple comparisons. In the phantom study, FA did not exceed 0.1 at any temperature. Consequently, pixels exceeding the threshold of 0.1 were removed from the temperature map. Intracranial CSF temperatures significantly differed between the four methods (p < 0.0001). The lowest temperature was 2nd-MC DTI with FA processing (mean, 35.62 °C), followed in order by c-DTI with FA processing (mean, 36.16 °C), 2nd-MC DTI (mean, 37.08 °C), and c-DTI (mean, 39.08 °C;p < 0.01 for each). Because the calculated temperature of ACSF was estimated to be lower than that of water, the temperature of 2nd-DTI with FA processing was considered reasonable. The method of 2nd-MC DTI with FA processing enabled determining intracranial CSF temperature with a reduction in CSF pulsation.

Visualization of Cerebrospinal Fluid Motion in the Whole Brain Using Three-dimensional Dynamic Improved Motion-sensitized Driven-equilibrium Steady-state Free Precession.

The feasibility of the 3D dynamic improved motion-sensitized driven-equilibrium steady-state free precession (3D dynamic iMSDE SSFP) was evaluated for visualizing CSF motion and the appropriate parameters were determined. Both flow phantom and volunteer studies revealed that linear ordering and the shortest acquisition duration time were optimal. 3D dynamic iMSDE SSFP provides good quality imaging of CSF motion in the whole brain and enables visualization of flow in arbitrary planes from a single 3D volume scan.

Optimal strategy for measuring intraventricular temperature using acceleration motion compensation diffusion-weighted imaging.

DWI thermometry is affected by CSF pulsation. To achieve more accurate determination of intraventricular temperature, we compared conventional DWI (c-DWI), acceleration motion compensation DWI (aMC-DWI), and motion compensation DWI (MC-DWI) when using two different b values (commonly used b value [1000 s/mm2] and theoretically optimized b value according to the diffusion coefficient of the CSF [400 s/mm2]). Eight healthy volunteers were scanned using a 3.0-T magnetic resonance (MR) system. The temperature map was created using the diffusion coefficient from DWI with b = 1000 and 400 s/mm2, respectively. The intraventricular temperatures in the lateral ventricles (LV) with less CSF pulsation, and the third ventricle (TV), which has more CSF pulsation, were compared between three techniques using the Friedman test. We measured the body temperature in the axilla to compare it with the intraventricular temperature. With b = 1000 s/mm2, the intraventricular temperatures in TV for c-DWI were significantly higher (43.12 ± 2.86 °C) than those for the aMC-DWI (37.68 ± 1.66 °C; P < 0.05), whereas those in LV were not significantly different (P = 0.093). With b = 400 s/mm2, the intraventricular temperatures in TV for c-DWI (75.07 ± 5.48 °C) were significantly higher than those for the aMC-DWI (38.63 ± 0.92 °C; P < 0.05), whereas those in LV were not significantly different (P = 0.093). aMC-DWI provided an intraventricular temperature that was close to or slightly higher than the body temperature in either condition. However, c-DWI- and MC-DWI-measured temperatures were higher than the body temperature, particularly in the TV. Thus, aMC-DWI can accurately determine the intraventricular temperature.

Diffusion-weighted MR imaging of the liver at 3.0 Tesla using TRacking Only Navigator echo (TRON): a feasibility study.

PURPOSE: To assess the feasibility of TRacking Only Navigator echo (TRON) for diffusion-weighted magnetic resonance imaging (DWI) of the liver at 3.0T. MATERIALS AND METHODS: Ten volunteers underwent TRON, respiratory triggered, and free breathing DWI of the liver at 3.0 Tesla (T). Scan times were measured. Image sharpness, degree of stair-step and stripe artifacts for the three methods were assessed by two observers. RESULTS: Mean scan times of TRON and respiratory triggered DWI relative to free breathing DWI were 34% and 145% longer respectively. In four of eight comparisons (two observers, two b-values, two slice orientations), TRON DWI image sharpness was significantly better than free breathing DWI, but inferior to respiratory triggered DWI. In two of four comparisons (two observers, two b-values), degree of stair-step artifacts in TRON DWI was significantly lower than in respiratory triggered DWI. Degree of stripe artifacts between the three methods was not significantly different. CONCLUSION: DWI of the liver at 3.0T using TRON is feasible. Image sharpness in TRON DWI is superior to that in free breathing DWI. Although image sharpness of respiratory triggered DWI is still better, TRON DWI requires less scan time and reduces stair-step artifacts.

[Clinical features of vitreous hemorrhage after photodynamic therapy for age-related macular degeneration].

PURPOSE: To study the clinical features of vitreous hemorrhage (VH) after photodynamic therapy (PDT) for age-related macular degeneration(AMD). MATERIALS AND METHODS: Twelve patients (12 eyes: 1.7% of the 718 eyes on which PDT was performed) who had vitrectomy due to massive VH after PDT for AMD were studied. Their medical records were reviewed and courses and characteristics were studied. RESULTS: Eight eyes (67%) were diagnosed as polypoidal choroidal vasculopathy and 7 eyes showed multiple clusters of grape-like lesions. Average greatest linear dimension (GLD) was 4533 microm, larger than common AMD. After vitrectomy, some cases retained choroidal neovascularization. Five eyes had another PDT and 3 eyes had a second vitrectomy due to recurrent vitreous hemorrhage. CONCLUSIONS: Both PCV and a large GLD are risk factors for a massive vitreous hemorrhage after PDT therapy for AMD. As many cases retain choroidal neovascularization many patients require additional treatment. Continued observation after vitrectomy is essential.

[Development of fat suppressed three-dimensional T1-weighted image using linear filling order for K-space].

We have developed a sequence for abdominal examination that fat suppressed 3D-T1W by a linear filling order using an adiabatic pulse for frequency selective fat suppression. We simulated the change in fat signal using a linear method and checked the starting point of data filling for the null point using a phantom of different T1 values. We then checked the contrast between the fat signal and liver. After checking by using simulation, a clinical evaluation was done. The change in fat signal was mostly the same after the fourth shot, and we were able to estimate the null point of the fat signal by the following parameters: TR, FA, TFE factor, and shot interval. Consequently, we could control the starting point of data filling in k-space for fat suppression. The contrast between fat and liver was improved because noise was reduced by the linear method. The sequence developed with the linear filling order using frequency selective fat suppression pulse proved to be useful.

[Visualization of the posterior vitreous membrane in diabetic macular edema patients using three-dimensional optical coherence tomography].

PURPOSE: To study the visualization of the vitreoretinal interface in diabetic macular edema patients using three-dimensional optical coherence tomography (3 D-OCT) and to compare it to surgical findings. METHODS: We prospectively examined the medical records of 25 patients (30 eyes) with diabetic macular edema measured by 3 D-OCT (optic disc and macular lesions) who received vitrectomy between August 2006 and February 2007. We compared the findings of 3 D-OCT to the findings during surgery using triamcinolone acetonide. RESULTS: Posterior vitreous membrane was found in 18 eyes using 3 D-OCT. The findings in all cases corresponded to operative findings. Six cases were characterized by posterior vitreous membrane attached to the optic disc and macular area. Twelve cases were characterized by posterior vitreous membrane diffusely attached to the posterior pole. CONCLUSIONS: Vitreoretinal interfaces were visualized using 3D-OCT and confirmed by operative findings. 3 D-OCT is an effective tool to determine the pathogenesis of diabetic macular edema.

[Multifocal choroiditis associated with serpiginous choroiditis and choroidal neovascularization: a case report].

BACKGROUND: We treated a patient with multifocal choroiditis (MFC) associated with serpiginous choroiditis and choroidal neovascularization (CNV). CASE: In a 27-year-old woman whose left eye showed serpiginous choroiditis near the optic disc and multiple irregular chorioretinal scars and exudates in peripheral and near-peripheral zones, fluorescein angiography demonstrated diffusely scattered hyperfluorescent dots and late leakage from retinal vessels. The lesion near the optic disc showed hypofluorescence in the early venous phase, and hyperfluorescence in the late phase. Sub-Tenon injection of triamcinolone acetonide did not effectively treat the CNV secondary to serpiginous choroiditis, but direct laser photocoagulation was successful, achieving improved visual acuity. CONCLUSIONS: We suggest that this patient's MFC and serpiginous choroiditis represented a single process rather than independent events. With lesions at the posterior pole, CNV developed secondarily. In this case, direct laser photocoagulation proved useful.

[Basic examination of CEMRA with 4D time-resolved angiography using keyhole (4D-TRAK) in 3T pelvic region].

Time-resolved MRA has recently been reported, and high-resolution MRA that does not miss timing is possible. In this examination, CEMRA that used 4D time-resolved angiography using keyhole (4D-TRAK) at 3T for the pelvic region was studied. 4D-TRAK is a method of using keyhole imaging together with sensitivity encoding (SENSE) and contrast-enhanced timing robust angio (CENTRA). The method changed flip angle (FA) and examined relative signal intensity, TR, TE, dynamic keyhole scan duration (DKSD) of the dilution contrast media, and keyhole% (KP). Image quality was examined with a blood vessel phantom. The presence of the partial echo method (PE) was examined in all cases. Relative signal intensity rose when FA increased. It has decreased in the PE method. TR did not show a difference by the PE method in FA15 degrees or more. DKSD was extended by the PE method. In the blood vessel Phantom, the PE method made the ringing artifacts remarkable. The artifacts that originated in keyhole imaging were observed. Shortening TR is difficult because of peculiar SAR to 3T. The PE method is not effective and becomes useless. It is necessary to note a point different from the parameter setting by 1.5T.

[Trial of artifact reduction in body diffusion weighted imaging development and basic examination of "TRacking Only Navigator"(TRON method)].

In recent years, the utility of body diffusion weighted imaging as represented by diffusion weighted whole body imaging with background body signal suppression (DWIBS), the DWIBS method, is very high. However, there was a problem in the DWIBS method involving the artifact corresponding to the distance of the diaphragm. To provide a solution, the respiratory trigger (RT) method and the navigator echo method were used together. A problem was that scan time extended to the compensation and did not predict the extension rate, although both artifacts were reduced. If we used only navigator real time slice tracking (NRST) from the findings obtained by the DWIBS method, we presumed the artifacts would be ameliorable without the extension of scan time. Thus, the TRacking Only Navigator (TRON) method was developed, and a basic examination was carried out for the liver. An important feature of the TRON method is the lack of the navigator gating window (NGW) and addition of the method of linear interpolation prior to NRST. The method required the passing speed and the distance from the volunteer's diaphragm. The estimated error from the 2D-selective RF pulse (2DSRP) of the TRON method to slice excitation was calculated. The condition of 2D SRP, which did not influence the accuracy of NRST, was required by the movement phantom. The volunteer was scanned, and the evaluation and actual scan time of the image quality were compared with the RT and DWIBS methods. Diaphragm displacement speed and the quantity of displacement were determined in the head and foot directions, and the result was 9 mm/sec, and 15 mm. The estimated error was within 2.5 mm in b-factor 1000 sec/mm(2). The FA of 2DSRP was 15 degrees, and the navigator echo length was 120 mm, which was excellent. In the TRON method, the accuracy of NRST was steady because of line interpolation. The TRON method obtained image quality equal to that of the RT method with the b-factor in the volunteer scanning at short actual scan time. The TRON method can obtain image quality equal to that of the RT method in body diffusion weighted imaging within a short time. Moreover, because scan time during planning becomes actual scan time, inspection can be efficiently executed.

Time-spatial Labeling Inversion Pulse (Time-SLIP) with Pencil Beam Pulse: A Selective Labeling Technique for Observing Cerebrospinal Fluid Flow Dynamics.

We assessed labeling region selectivity on time-spatial labeling inversion pulse (Time-SLIP) with pencil beam pulse (PB Time-SLIP) for the use of visualizing cerebrospinal fluid (CSF) flow dynamics. We compared the selectivity of labeling to the third and fourth ventricles between PB Time-SLIP and conventional Time-SLIP (cTime-SLIP) in eight volunteers and one patient using a 1.5T MRI. PB Time-SLIP provided more selective labeling in CSF than cTime-SLIP, particularly in complex anatomical regions.

Photodynamic therapy for age-related macular degeneration in Japanese patients: results after one year.

PURPOSE: To evaluate the effects of photodynamic therapy (PDT) with verteporfin 1 year after treatment in Japanese patients with age-related macular degeneration (AMD) and subfoveal choroidal neovascularization. METHODS: Between May 2004 and March 2005, PDT was performed on 102 eyes of 98 patients (60 men and 38 women) with AMD and subfoveal choroidal neovascularization. Patients were followed for at least 12 months after PDT. RESULTS: The mean visual acuities in logarithm of the minimum angle of resolution (logMAR) units were 0.978 at baseline, 0.919 at 3 months, 0.895 at 6 months, 0.892 at 9 months, and 0.874 at 12 months. After PDT, the logMAR visual acuity improved by >0.3 logMAR units or more in 28 eyes (27%) and deteriorated by >0.3 logMAR units or more in 13 eyes (13%). Stable or improved vision was achieved in 93% of patients with polypoidal choroidal vasculopathy (PCV). CONCLUSIONS: The visual outcome in our patients was similar to that of an earlier major Japanese study, and similar to or better than outcomes in Western studies. Differences between Caucasians and Japanese might influence the characteristics of PCV. It is possible that PDT is more effective for AMD patients with PCV than for other AMD patients. Further observations and longer follow-up are necessary.

[Vitrectomy for chronic macular edema associated with branch retinal vein occlusion].

PURPOSE: To study the outcome after vitrectomy for chronic and acute macular edema associated with branch retinal vein occlusion (BRVO). MATERIALS AND METHODS: Medical charts of fifty-five patients (55 eyes) who underwent vitrectomy for macular edema associated with BRVO were reviewed retrospectively. Patients were followed up for more than one year after the vitrectomy. We compared the visual and structural outcome between an early group (i. e., edema lasting less than one year) and a late group (i.e., edema lasting more than one year). RESULTS: The mean visual acuity improved significantly from 0.088 to 0.163 in the early group and from 0.147 to 0.132 in the late group. Seventy percent of the cases improved in angiographic findings and eighty percent of the cases improved in optical coherence tomography findings. CONCLUSIONS: Vitrectomy for chronic macular edema even lasting more than one year after BRVO seems to be effective, depending on the case.

[Study of the causes of poor visual prognosis in photodynamic therapy for age-related macular degeneration].

PURPOSE: To study the factors for poor visual outcome in photodynamic therapy(PDT) for age-related macular degeneration (AMD) patients with subfoveal choroidal neovascularization. MATERIALS AND METHODS: Medical charts of eighty-five patients (88 eyes) who had AMD with subfoveal choroidal neovascularization were reviewed in the study. All patients were followed up by visual acuity assessment, angiography, and optical coherence tomography at least 6 months after PDT. RESULTS: Out of 11 cases of poor visual outcome, 7 cases showed cystoid macular edema (CME) before treatment and 4 cases showed massive subretinal hemorrhage and/or vitreous hemorrhage after treatment. Some cases with CME had a worse visual outcome than cases without CME. CONCLUSIONS: Some of the factors for poor visual outcome after PDT for AMD are the existence of CME before treatment and polypoidal choroidal vasculopathy (PCV). In some cases, PCV caused massive subretinal hemorrhage and/or vitreous hemorrhage after treatment.

T1ρ mapping improvement using stretched-type adiabatic locking pulses for assessment of human liver function at 3T.

PURPOSE: The purpose of this study is to investigate the performance of stretched-type adiabatic spin lock pulses for homogeneous spin locking with a flexible spin lock time (TSL) setting. METHODS: T1ρ values were obtained from 61 patients and five normal volunteers who were categorized using the Child-Pugh classification and scanned using each spin lock pulse type. The pulses used were the block and two kinds of hyperbolic secant (HS); HS8_10, and HS8_5. Visual scoring was categorized using a four point scale (1:Severe, 2:Moderate, 3:Mild and 4:None) to evaluate the homogeneity of the T1ρ map and the source images obtained by each spin lock pulse. Mean T1ρ values among the patient groups with different Child-Pugh classification were compared. RESULTS: The visual assessment scores were 1.98 ± 1.05 for block pulse locking, 3.87 ± 0.39 for HS8_10 pulse locking, and 3.83 ± 0.45 for HS8_5 pulse locking, respectively. The scores between block pulse and HS8_10 were significantly different (p < 0.001), as were those between block pulse and HS8_5 (p < 0.001). The median T1ρ values of normal liver function, Child-Pugh A, and Child-Pugh B or C were 37.00 ms, 40.77 ms, and 42.20 ms for block pulse, 46.75 ms, 50.78 ms, and 55.60 ms for HS8_10, and 48.80 ms, 55.42 ms, and 57.80 ms for HS8_5, respectively. CONCLUSION: The spin locking sequence using stretched-type adiabatic pulses provides homogeneous liver T1ρ maps with reduced artifact and is necessary for a robust evaluation of liver function using T1ρ.

Volume isotropic simultaneous interleaved black- and bright-blood imaging: a novel sequence for contrast-enhanced screening of brain metastasis.

We introduced and optimized a novel sequence of fast (about 4 min), volumetric, high resolution, simultaneous bright- and black-blood imaging with sufficient T1 contrast between enhanced metastasis and surrounding brain parenchyma for their differentiation. This proposed sequence can be used for 3-dimensional volumetric T1-weighted bright- and black-blood imaging in contrast-enhanced studies and may be promising for detecting small brain metastases by improving differentiation between blood vessels and small brain metastases.