3D Fast Spoiled Gradient Echo Research Articles

Comparison between 2D FSE T2-weighted Dixon MRI and contrast-enhanced 2D FSE and 3D FSPGR T1-weighted Dixon MRI to quantify inflammation in hands of patients with early rheumatoid arthritis

PurposeThe purpose of this study was to compare two-dimensional (2D) T2-weighted, contrast-enhanced 2D T1-weighted and contrast-enhanced three-dimensional (3D) T1-weighted Dixon MRI sequences to assess disease activity using the RAMRIS scoring system in hands of patients with early rheumatoid arthritis. Materials and methodsTwenty-five patients (19 women, 6 men; mean age 51.4 years ± 12.7 years [SD], age range: 28–70 years) with rheumatoid arthritis prospectively underwent MRI examination of both hands at 1.5 T using 2D fast spin-echo (FSE) T2-weighted, contrast-enhanced 2D FSE T1-weighted and contrast-enhanced 3D fast spoiled gradient echo (FSPGR) T1-weighted Dixon sequences. Three radiologists independently assessed disease activity according to RAMRIS using Dixon water-only and fat-only images. Intraclass correlation coefficients (ICC) were calculated to assess inter-technique and interobserver agreements. ResultsAgreement to assess total RAMRIS score was very good between the MRI protocols (mean ICC ranging from 0.81 to 0.93) and between readers (mean ICC ranging from 0.91 to 0.94). Mean total RAMRIS scores of the three readers were significantly greater with contrast-enhanced 3D FSPGR T1-weighted (42.73 ± 29.39) than with contrast-enhanced 2D FSE T1-weighted (35.81 ± 25.48) and 2D FSE T2-weighted (32.20 ± 25.06) Dixon sequences. Conclusion2D FSE T2-weighted, contrast-enhanced 2D FSE T1-weighted Dixon and contrast-enhanced 3D FSPGR T1-weighted Dixon protocols are reproducible alternatives for the RAMRIS scoring in hands of patients with early rheumatoid arthritis. Coupling contrast-enhanced 3D FSPGR T1-weighted and 2D FSE T2-weighted sequences might be the most efficient option to completely assess the rheumatoid arthritis -related synovial and bone changes with the Dixon method.

Deep Learning Reconstruction to Improve the Quality of MR Imaging: Evaluating the Best Sequence for T-category Assessment in Non-small Cell Lung Cancer Patients.

Deep learning reconstruction (DLR) has been recommended as useful for improving image quality. Moreover, compressed sensing (CS) or DLR has been proposed as useful for improving temporal resolution and image quality on MR sequences in different body fields. However, there have been no reports regarding the utility of DLR for image quality and T-factor assessment improvements on T2-weighted imaging (T2WI), short inversion time (TI) inversion recovery (STIR) imaging, and unenhanced- and contrast-enhanced (CE) 3D fast spoiled gradient echo (GRE) imaging with and without CS in comparison with thin-section multidetector-row CT (MDCT) for non-small cell lung cancer (NSCLC) patients. The purpose of this study was to determine the utility of DLR for improving image quality and the appropriate sequence for T-category assessment for NSCLC patients. As subjects for this study, 213 pathologically diagnosed NSCLC patients who underwent thin-section MDCT and MR imaging as well as T-factor diagnosis were retrospectively enrolled. SNR of each tumor was calculated and compared by paired t-test for each sequence with and without DLR. T-factor for each patient was assessed with thin-section MDCT and all MR sequences, and the accuracy for T-factor diagnosis was compared among all sequences and thin-section CT by means of McNemar's test. SNRs of T2WI, STIR imaging, unenhanced thin-section Quick 3D imaging, and CE-thin-section Quick 3D imaging with DLR were significantly higher than SNRs of those without DLR (P < 0.05). Diagnostic accuracy of STIR imaging and CE-thick- or thin-section Quick 3D imaging was significantly higher than that of thin-section CT, T2WI, and unenhanced thick- or thin-section Quick 3D imaging (P < 0.05). DLR is thus considered useful for image quality improvement on MR imaging. STIR imaging and CE-Quick 3D imaging with or without CS were validated as appropriate MR sequences for T-factor evaluation in NSCLC patients.

Impairment of motor skills in children with achondroplasia-usefulness of brain and cranio-cervical junction evaluation by quantitative magnetic resonance imaging: a case-control study.

Most infants and children with achondroplasia show delayed motor skill development; however, some patients may have clinical consequences related to cranio-cervical junction stenosis and compression. To assess, using brain magnetic resonance imaging (MRI), quantitative variables linked to neuromotor impairment in achondroplasic children. In total, 24 achondroplasic children underwent pediatric neurological assessment and were grouped in two cohorts according to relevant motor skill impairment. Achondroplasic children with (n=12) and without (n=12) motor symptoms were identified, and brain MRI scans were quantitatively evaluated. 3D fast spoiled gradient echo T1-weighted images were used to assess: supratentorial intracranial volumes (SICV); supratentorial intracranial brain volume (SICBV); SICV/SICBV ratio; posterior cranial fossa volume (PCFV); posterior cranial fossa brain volume (PCBFV); PCFV/PCFBV ratio; ventricular and extra-ventricular cerebrospinal fluid (CSF) volumes; foramen magnum (FM) area; and jugular foramina (JF) areas. In both groups, SICV/SICBV ratio, supratentorial ventricular and extra-ventricular space volumes were increased while SICBV was increased only in the asymptomatic group (P < 0.05). PCFV/PCFBV ratio, IV ventricle, infratentorial extra-ventricular spaces volumes were reduced (P < 0.05) in the symptomatic group while PCFBV was increased only in the asymptomatic group (P < 0.05). Foramen magnum (FM) area was more reduced in the symptomatic group than the asymptomatic group (P < 0.05) but no correlation between FM area and ventriculomegaly was found (P > 0.05). Evaluation of the FM area together with infratentorial ventricular and extra-ventricular space volume reduction may be helpful in differentiating patients at risk of developing motor skill impairment. Further investigation is needed to better understand the temporal profile between imaging and motor function in order to propose possible personalized surgical treatment.

Quantitative volume and dynamic contrast-enhanced MRI derived perfusion of the infrapatellar fat pad in patellofemoral pain.

Patellofemoral pain (PFP) is a common knee condition and possible precursor of knee osteoarthritis (OA). Inflammation, leading to an increased perfusion, or increased volume of the infrapatellar fat pad (IPFP) may induce knee pain. The aim of the study was to compare quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters, as imaging biomarkers of inflammation, and volume of the IPFP between patients with PFP and controls and between patients with and without IPFP edema or joint effusion. Patients with PFP and healthy controls were included and underwent non-fat suppressed 3D fast-spoiled gradient-echo (FSPGR) and DCE-MRI. Image registration was applied to correct for motion. The IPFP was delineated on FSPGR using Horos software. Volume was calculated and quantitative perfusion parameters were extracted by fitting extended Tofts' pharmacokinetic model. Differences in volume and DCE-MRI parameters between patients and controls were tested by linear regression analyses. IPFP edema and effusion were analyzed identically. Forty-three controls and 35 PFP patients were included. Mean IPFP volume was 26.04 (4.18) mL in control subjects and 27.52 (5.37) mL in patients. Median Ktrans was 0.017 (0.016) min-1 in control subjects and 0.016 (0.020) min-1 in patients. None of the differences in volume and perfusion parameters were statistically significant. Knees with effusion showed a higher perfusion of the IPFP compared to knees without effusion in patients only. The IPFP has been implicated as source of knee pain, but higher DCE-MR blood perfusion, an imaging biomarker of inflammation, and larger volume are not associated with PFP. Patient's knees with effusion showed a higher perfusion, pointing towards inflammation.

Non-contrast MR angiography versus contrast enhanced MR angiography for detection of renal artery stenosis: a comparative analysis in 400 renal arteries.

In this study, we compared non-contrast MR angiography (NC-MRA) with conventional 3D contrast-enhanced MRA (CE-MRA) in patients suspected to have renal artery stenosis (RAS). From March 2014 to March 2020, patients who were evaluated for RAS and had a glomerular filtration rate > 30ml/min/1.73 m2 underwent MR imaging on a 3T MR Scanner (Signa Hdxt General Electrics, Milwaukee, USA) using a Torso PA coil. The NC-MRA sequence was performed using a 3D fat-suppressed inflow inversion recovery balanced steady state free precession (SSFP) sequence (Inhance 3D Inflow IR, GE Medical) whereas the CE-MRA sequence was a 3D fast spoiled gradient echo (FSPGR). Overall quality of images was rated 1 to 4. Stenosis was reported as grade 1 (Normal), 2 (< 50% narrowing), 3 (> 50% narrowing) and 4 (Total occlusion). Grade 3 and 4 were considered haemodynamically significant. During the study period, 201 patients were enrolled (400 renal arteries). For hemodynamically significant (grade 3/4) stenosis, NC-MRA correctly diagnosed 72 patients (95 arteries) while in 2 patients (2 arteries), NC-MRA underdiagnosed the stenosis as grade 2 (these were found to have grade 3 stenosis on CE-MRA). The kappa value of agreement between NC-MRA and CE-MRA for detection of RAS showing excellent agreement (p < 0.001). In one of the largest series of patients so far, we found that NC-MRA is a viable alternative to CE-MRA for detection of RAS, highly correlating with CE-MRA for grade of stenosis and with additional advantage of lack of gadolinium based contrast agents toxicity.

Association Functional MRI Studies of Resting-State Amplitude of Low Frequency Fluctuation and Voxel-Based Morphometry in Patients With Occupational Noise-Induced Hearing Loss.

To investigate changes in brain functional activity among occupational noise-induced hearing loss (NIHL) with tinnitus patients, using resting-state brain magnetic resonance imaging (Rs-fMRI) and voxel-based morphometry (VBM). Mild (27) and Relative severe (15) patient groups, 30 matched healthy group, scanned by Rs-fMRI and T1WI 3D fast spoiled gradient echo, FSPGR, using voxel-based morphometry and amplitude of low frequency fluctuation to analyze the differences. Brain gray matter volume was significantly different among the three groups in the left occipitotemporal lateral gyrus, the anterior cingulate gyrus, the bilateral angular gyrus, the precuneus, and near the midline area of the cerebellum. The Rs-fMRI changes showed that amplitude of low frequency fluctuation differed significantly among the three groups in the right superior temporal gyrus, the right inferior frontal gyrus, and the right angular gyrus. All this provides a new perspective for understanding the pathophysiological mechanism of occupational noise-induced hearing loss and provides some theoretical bases for subsequent treatment.

Evaluation of Long-term Fluctuation of Geometric Distortion in MRI for Radiation Therapy Planning by Using an Automatic Analysis Tool

High tissue contrast in magnetic resonance imaging (MRI) allows better radiotherapy planning. However, geometric distortion in MRI induces inaccuracies affecting such planning, making it necessary to evaluate the characteristics of such geometric distortion. Although many studies have considered geometric distortion, most of these involved measurements performed only a few times. In this study, we evaluated MRI device-specific geometric distortion over long term and measured its variation by using an automatic analysis tool. The result showed that geometric distortion increased with distance from the center along both lateral and longitudinal directions. Specifically, the average distortion rate and average diameter error over the full measurement period increased by up to 1.02% and 1.96 mm, respectively, when using T1 weighted Image (WI) 3D fast spoiled gradient echo (FSPGR) at R15. In the case of T2 WI 2D fast spin echo (FSE) at R15, the standard deviation of the distortion rate and diameter error increased up to 0.38%, 0.72 mm, respectively. We conclude that periodic quality assurance of geometric distortion should be performed in order to maintain geometric distortion within allowable values.

A Novel 3D-Printed Patient Positioning Platform to Accommodate Curved Couch of MR Scanner Optimizes Precision Treatment Planning Workflow for Abdominal Radiotherapy.

Magnetic Resonance Imaging (MR) is increasingly used in treatment planning (TP) owing to superior soft tissue contrast versus computed tomography (CT). Organ deformation in patient positioning on a curved MR couch versus a flat CT couch causes registration difficulties. This may lead to contour errors and tumor volume misjudgment, particularly in organs poorly visualized on CT (i.e. liver). MR-based simulation systems (MR-BSS) address this issue but are not widely available. In this study, we fabricated a 3D-printed platform (3D-PP) adapted to the MR couch and body array to enable scans in the TP position and optimize MR-guided TP in the absence of a dedicated MR-BSS. We demonstrate that a 3D-PP is low cost, does not interfere with image quality, and is easily implemented by radiology staff. The 3D-PP was drafted with computer-aided design to fit the table arc and 12 channel body array coil of a 1.5 T, 70 cm wide bore, MR scanner. The 3D-PP creates a flat surface to position an immobilization vacuum bag typically used in treatment. The 3D-PP consists of ¼” thick deck and 3/32” thick alignment wings mounted on ten risers. The deck and alignment wings are polyoxymethylene homopolymer laser-cut with a contact-free CO2 beam. Risers are fabricated from polylactide in a thermoplastic 3D printer. A urethane immobilization vacuum cushion (88 x 55 cm, 15 L fill) was fabricated for an 8-channel upper annular MR phantom. CT was acquired in an 85 cm bore simulation CT (120kVp, 512x512 in-plane dimensions, 0.11cm x 0.11cm pixel size, 2mm thickness). Standard body MR sequences were done including single shot fast spin echo (SS-FSE), 3D fast spoiled gradient echo with fat suppression(FSPGR FS), T2 fat suppression(T2 FS), balanced steady-state free precession (BSSFP), dual echo fast spin echo(DE FSE), and diffusion weight imaging (DWI). MR and CT scans were exported to a treatment planning system and fused using a local correlation algorithm capable of both rigid and deformable registration. An anthropomorphic phantom and quality control devices were employed for MR scans. SS-FSE, FSPGR, FSPGR FS, T2 FS, BSSFP, DEFSE, and DWI were analyzed to determine the effect of any artifacts contributed by the 3D-PP. Neither appreciable signal loss nor artifact were observed on any scan. Each MR-CT fusion required negligible computation time (< 2 seconds). In-plane registration was within sub-pixel accuracy for every slice in each sequence. We report a new, low cost approach to optimize MR-guided TP. A 3D-PP enables MR scans in the simulated TP position without appreciable loss of image quality or interruption of radiology workflow. A 3D-PP in a 70 cm wide bore MR system accommodates most treatment positions, including wing board. We are implementing this process into our abdominal SBRT workflow. The 3D-PP design and fabrication can be modified for the workflow of most clinics.

Common and Uncommon Artifacts in T1 FLAIR SAG Sequences of MRI Brain

ObjectiveThis study aims at identifying, classifying, and measuring the frequency the different artifacts that show up in the images of the Sagittal T1 Fluid Attenuated Inversion Recovery (FLAIR) sequence. Materials and MethodsA total of 101 subjects underwent brain magnetic resonance imaging examination with the following sequences: Axial T1 FLAIR, Axial T2-weighted imaging, Diffusion Weighted Imaging, 2D Multiple Echo Recombined Gradient Echo, Sagittal T1 FLAIR, Coronal T2 Turbo Spin Echo, Spin Echo T1-weighted imaging, and 3D Fast Spoiled Gradient-echo. In these images, we observed the following categories of artifacts: (a) ghost artifacts, (b) aliasing behind the occipital bone, (c) aliasing inside the sphenoid cavity, (d) susceptibility artifacts, and (e) pulsation artifacts. In order to recognize and verify the artifacts, we used not only the Sagittal T1 FLAIR sequence, but also Sagittal reconstructions from the 3-dimensional Fast Spoiled Gradient-echo sequence and the other routine sequences. ResultsAliasing artifacts and especially aliasing of nose are present in 41% of the cases. In 45% of these cases the uncommon aliasing artifacts, which took place into the brain parenchyma (sphenoid cavity, subarachnoid bay, or pituitary) originated from nose. In 33% of the subjects, ghost artifacts are presented, which stem from the nose, the orbits, or other pulsating structures (pulsation artifacts) or even from fat tissue. Moreover, susceptibility artifacts comprise 8% of all the artifacts. Finally, 19% of brains were presented without artifact. ConclusionsWe suggest in addition to T1 FLAIR, the application of Sagittal SE or TSE sequences in magnetic resonance imaging examination of brain, trying to include the nose in the square of FOV.

Identifying cardiovascular risk factors that impact cerebrovascular reactivity: An ASL MRI study.

To maintain cerebral blood flow (CBF), cerebral blood vessels dilate and contract in response to blood supply through cerebrovascular reactivity (CR). Cardiovascular (CV) disease is associated with increased stroke risk, but which risk factors specifically impact CR is unknown. Prospective longitudinal. Fifty-three subjects undergoing carotid endarterectomy or stenting. 3T, 3D pseudo-continuous arterial spin labeling (PCASL) ASL, and T1 3D fast spoiled gradient echo (FSPGR). We evaluated group differences in CBF changes for multiple cardiovascular risk factors in patients undergoing carotid revascularization surgery. PRE (baseline), POST (48-hour postop), and 6MO (6 months postop) whole-brain CBF measurements, as 129 CBF maps from 53 subjects were modeled as within-subject analysis of variance (ANOVA). To identify CV risk factors associated with CBF change, the CBF change from PRE to POST, POST to 6MO, and PRE to 6MO were modeled as multiple linear regression with each CV risk factor as an independent variable. Statistical models were performed controlling for age on a voxel-by-voxel basis using SPM8. Significant clusters were reported if familywise error (FWE)-corrected cluster-level was P < 0.05, while the voxel-level significance threshold was set for P < 0.001. The entire group showed significant (cluster-level P < 0.001) CBF increase from PRE to POST, decrease from POST to 6MO, and no significant difference (all voxels with P > 0.001) from PRE to 6MO. Of multiple CV risk factors evaluated, only elevated systolic blood pressure (SBP, P = 0.001), chronic renal insufficiency (CRI, P = 0.026), and history of prior stroke (CVA, P < 0.001) predicted lower increases in CBF PRE to POST. Over POST to 6MO, obesity predicted lower (P > 0.001) and cholesterol greater CBF decrease (P > 0.001). The CV risk factors of higher SBP, CRI, CVA, BMI, and cholesterol may indicate altered CR, and may warrant different stroke risk mitigation and special consideration for CBF change evaluation. 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:734-747.

Radiomics Analysis of DTI Data to Assess Vision Outcome After Intravenous Methylprednisolone Therapy in Neuromyelitis Optic Neuritis.

Neuromyelitis optica-optic neuritis (NMO-ON) patients are routinely treated with intravenous methylprednisolone (IVMP). For the patients nonresponsive to IVMP, more effective but aggressive therapy of plasma exchange (PE) should be employed instead of IVMP in the first line. To assess the visual outcomes of NMO-ON patients after IVMP by radiomics analysis of whole brain diffusion tensor imaging (DTI) data. Retrospective. In all, 57 NMO-ON patients receiving IVMP therapy for 3 days. 3.0T; DTI images acquired by a single-shot echo planar image sequence; T1 images acquired by 3D fast spoiled gradient echo (3D-FSPGR) MRI. In all, 200 DTI measures were extracted from the DTI data and employed as features to construct a radiomics assessment model for visual outcomes of NMO-ON patients after IVMP. The assessment performance was evaluated by area under the receiver operating characteristic curve (AUC), classification accuracy (ACC), sensitivity, specificity, and positive and negative predicted values (PPV and NPV). The selected DTI measures would reveal the white matter impairments related to visual recovery of NMO-ON patients. The relationship between the selected DTI measures and the clinical visual characteristics were investigated by Pearson correlation, Spearman's rank correlation, and one-way analysis of variance analysis. The radiomics model obtained an ACC of 73.68% (P = 0.002), AUC of 0.7931, sensitivity of 0.6207, specificity of 0.8571, PPV of 0.8182, and NPV of 0.6857 in assessing visual outcomes of the NMO-ON patients after IVMP treatment. The selected DTI measures revealed white matter impairments related to the visual outcomes in the white matter tracts of vision-relevant regions, motor-related regions, and corpus callosum. The white matter impairments were found significantly correlated with the disease duration and the length of lesions in the optic nerve. Radiomics analysis of DTI data has great potential in assessing visual outcomes of NMO-ON patients after IVMP therapy. 2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:1365-1373.

A Comparison of Black-blood T2 Mapping Sequences for Carotid Vessel Wall Imaging at 3T: An Assessment of Accuracy and Repeatability.

Purpose:This study is to compare the accuracy of four different black-blood T2 mapping sequences in carotid vessel wall.Methods:Four different black-blood T2 mapping sequences were developed and tested through phantom experiments and 17 healthy volunteers. The four sequences were: 1) double inversion-recovery (DIR) prepared 2D multi-echo spin-echo (MESE); 2) DIR-prepared 2D multi-echo fast spin-echo (MEFSE); 3) improved motion-sensitized driven-equilibrium (iMSDE) prepared 3D FSE and 4) iMSDE prepared 3D fast spoiled gradient echo (FSPGR). The concordance correlation coefficient and Bland–Altman statistics were used to compare the sequences with a gold-standard 2D MESE, without blood suppression in phantom studies. The volunteers were scanned twice to test the repeatability. Mean and standard deviation of vessel wall T2, signal-to-noise (SNR), the coefficient of variance and interclass coefficient (ICC) of the two scans were compared.Results:The phantom study demonstrated that T2 measurements had high concordance with respect to the gold-standard (all r values >0.9). In the volunteer study, the DIR 2D MEFSE had significantly higher T2 values than the other three sequences (P < 0.01). There was no difference in T2 measurements obtained using the other three sequences (P > 0.05). iMSDE 3D FSE had the highest SNR (P < 0.05) compared with the other three sequences. The 2D DIR MESE has the highest repeatability (ICC: 0.96, [95% CI: 0.88–0.99]).Conclusion:Although accurate T2 measurements can be achieved in phantom by the four sequences, in vivo vessel wall T2 quantification shows significant differences. The in vivo images can be influenced by multiple factors including black-blood preparation and acquisition method. Therefore, a careful choice of acquisition methods and analysis of the confounding factors are required for accurate in vivo carotid vessel wall T2 measurements. From the settings in this study, the iMSDE prepared 3D FSE is preferred for the future volunteer/patient scans.

Fat suppression at three-dimensional T1-weighted MR imaging of the hands: Dixon method versus CHESS technique.

To compare the effectiveness of fat suppression and the image quality of the Dixon method with those of the chemical shift-selective (CHESS) technique in hands of normal subjects at non-enhanced three-dimensional (3D) T1-weighted MR imaging. Both hands of 14 healthy volunteers were imaged with 3D fast spoiled gradient echo (FSPGR) T1-weighted Dixon, 3D FSPGR T1-weighted CHESS and 3D T1-weighted fast spin echo (FSE) CHESS sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFSBM) and soft tissues (EFSST) in 20 joints per subject. One radiologist measured the signal-to-noise ratio (SNR) in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects (P<0.0083), paired t-test (P<0.05) and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and interobserver agreement. EFSBM was statistically significantly higher for the 3D FSPGR T1-weighted Dixon than for the 3D FSPGR T1-weighted CHESS sequence and the 3D FSE T1-weighted CHESS sequence (P<0.0001). EFSST was statistically significantly higher for the 3D FSPGR T1-weighted Dixon than for the 3D FSPGR T1-weighted CHESS sequence (P<0.0011) and for the 3D FSE T1-weighted CHESS sequence in the axial plane (P=0.0028). Mean SNR was statistically significantly higher for 3D FSPGR T1-weighted Dixon sequence than for 3D FSPGR T1-weighted CHESS and 3D FSE T1-weighted CHESS sequences (P<0.0001). The Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 3D T1-weighted MR imaging of the hands.

Pulse sequence considerations for simulation and postimplant dosimetry of prostate brachytherapy

PurposeThe purpose of this work is to present a brief review of MRI physics principles pertinent to prostate brachytherapy, and a summary of our experience in optimizing protocols for prostate brachytherapy applications. Methods and MaterialsWe summarized essential MR imaging characteristics and their interplays that need to be considered for prostate brachytherapy applications. These include spatial resolution, signal-to-noise ratio, image contrast, artifacts, geometric distortion, specific absorption rate, and total scan time. We further described the optimization of the protocols for three pulse sequences: three-dimensional (3D) fast-spoiled gradient echo sequence for T1-weighted imaging, 3D fast-spin echo sequence for T2-weighted imaging, and 3D fast imaging in steady-state precession sequence for combined T1 and T2-weighed imaging. The utilization of an endorectal coil was also described. ResultsUsing the optimized protocols, we acquired high-quality images of the entire prostate within 3–5 minutes for each sequence. These images display the desired image contrasts and a spatial resolution that is equal to or better than 0.59 mm × 0.73 mm × 1.2 mm. While 3D fast-spoiled gradient echo sequence and 3D fast-spin echo sequence depict radioactive seed markers and anatomic structures separately, 3D fast imaging in steady-state precession sequence demonstrates great promise for imaging both seed markers and prostate anatomy simultaneously in a single acquisition. ConclusionsWe have optimized current MRI protocols and demonstrated that the anatomic structures and positive contrast radioactive seed markers for prostate post-implant dosimetry can be adequately imaged either separately or simultaneously using different pulse sequences within a total scan time of 3–5 minutes each.

Correlation between MRI features and metal compositions of gallstones

Objective To analyze the correlation between the metal components and MRI signal intensities of gallstones, to investigate the causes of gallstone signal features on MRI. Methods The MRI data and the metal components of the gallstones in vivo and in vitro of 30 patients were retrospectively analyzed. The MR sequences, namely 3D fast spoiled gradient-echo with fat saturation T1-weighted imaging (3D-FSPGR-FS T1WI), fast spoiled gradient-echo with fat saturation T1-weighted imaging (FSPGR-FS T1WI), fast imaging employing steady-state acquisition (FIESTA) and fast spin-echo T2-weighted imaging with fat saturation (FSE-FS T2WI), were performed on the gallstones in vivo and in vitro. According to the characteristics of the surface and cross section, gallstones were divided into pigment gallstones(n=16) and cholesterol gallstones(n=14). The MR signal characteristics of the gallstones were observed and the signal intensity rates of the gallstones were calculated. Preoperatively, the signal intensity rates of cholesterol and pigment stones of each MR sequence were compared by using t test and Mann-Whiteney U test. Postoperatively, the signal intensity rates of the fresh, dried and re-soaked gallstones were compared by using paired t test and Wilcoxon test. The correlation between the signal intensity rates of gallstones on the 3D-FSPGR-FS sequence and their metal components was analyzed by using Linear Regression analysis. Results The pigment gallstones showed high signal intensity on the 3D-FSPGR-FS T1WI. The signal intensity rates of the pigment gallstones were higher than the rates of the cholesterol gallstones on the 3D-FSPGR-FS T1WI, which were 2.02±0.53 and 0.51±0.24 (t=10.26, P< 0.01), respectively. On the 3D-FSPGR-FS T1WI, the signal intensity rates of the drying pigment stones were significantly lower than the rates of the fresh ones, the rates of the two states of the pigment gallstones were 0.21±0.06 and 1.42±0.35(t= 13.49, P<0.01),respectively. The signal intensity rates of pigment gallstones showed significant rebound after re-soaking, the rates of the two states of the pigment gallstones were 0.21±0.06 and 1.68±0.86(t=-6.63, P< 0.01),respectively. The metal components of pigment gallstones were significantly higher than the cholesterol stones. In the pigment gallstones and cholesterol gallstones, the medians of the Calcium were 28.186 and 2.347 mg/g (Z=-4.66, P< 0.01), respectively. For pigment gallstones, there was a significant correlation between the calcium and the signal intensity rate on 3D-FSPGR-FS T1WI. The regression equation of linear regression analysis was SI= 65.40 logCa-166.67. Conclusions The pigment gallstones containing much more water and metal showed high signal intensity on 3D-FSPGR-FS T1WI. The Calcium in the pigment gallstones may be the main cause for this MR appearance. Key words: Cholelithiasis; Magnetic resonance imaging; Comparative study

Suitability of antral follicle counts and computer-assisted analysis of ultrasonographic and magnetic resonance images for estimating follicular reserve in porcine, ovine and bovine ovaries ex situ.

This study was conducted to determine if correlations exist between the numbers of microscopic follicles comprising ovarian follicular reserve (OFR) and antral follicle counts (AFCs), and to assess the usefulness of computerized analyses of ovarian ultrasonograms and magnetic resonance (MR) images for estimating OFR in excised porcine, ovine and bovine ovaries. As a pre-requisite to these analyses, we characterized and compared ovarian cortical histomorphology and follicle populations in the three species varying in prolificacy and overall reproductive longevity, and hence the total number of microscopic and antral follicles. Ultrasonographic and MR images were obtained at the scanner settings optimized to provide opposing contrasts between antral follicles and the ovarian stroma. Commercially available ImageProPlus® analytical software was used to calculate numerical pixel values (NPVs) and pixel heterogeneity (standard deviation of the pixel values) along the computer-generated lines (4-6) placed in the area corresponding to the ovarian cortex. The numbers of primordial (r = 0.38, P < 0.01) and intermediate follicles (r = 0.37, P < 0.01) were correlated with the numbers of antral follicles in bovine ovarian sections. The numbers of primordial (r = 0.28, P < 0.05), intermediate (r = 0.31, P < 0.01) and primary follicles (r = 0.27, P < 0.05) correlated directly with mean NPVs of the ultrasonographic ovarian images in cattle. There was a negative correlation between primary follicle numbers and NPVs of MR images (3D FAST-SPOILED GRADIENT ECHO) of the porcine ovarian cortex (r = -0.31, P < 0.05). To summarize, the numbers of primordial and intermediate follicles could only be estimated from AFCs in cows. Using ultrasound NPVs, the numbers of primordial, intermediate and primary follicles could be directly estimated in bovine ovaries and the quantitative image attributes of MR images were useful for quantifying porcine primary follicles. The bovine ovarian model is compatible with human situation and hence future studies should be undertaken to ascertain the usefulness of AFCs and ultrasonographic image analyses for estimating OFR in women.

SU‐C‐17A‐02: Sirius MRI Markers for Prostate Post‐Implant Assessment: MR Protocol Development

Purpose:Currently, CT is used to visualize prostate brachytherapy sources, at the expense of accurate structure contouring. MRI is superior to CT for anatomical delineation, but the sources appear as voids on MRI images. Previously we have developed Sirius MRI markers (C4 Imaging) to replace spacers to assist source localization on MRI images. Here we develop an MRI pulse sequence protocol that enhances the signal of these markers to enable MRI‐only post‐implant prostate dosimetric analysis.Methods:To simulate a clinical scenario, a CIRS multi‐modality prostate phantom was implanted with 66 markers and 86 sources. The implanted phantom was imaged on both 1.5T and 3.0T GE scanners under various conditions, different pulse sequences (2D fast spin echo [FSE], 3D balanced steadystate free precession [bSSFP] and 3D fast spoiled gradient echo [FSPGR]), as well as varying amount of padding to simulate various patient sizes and associated signal fall‐off from the surface coil elements. Standard FSE sequences from the current clinical protocols were also evaluated. Marker visibility, marker size, intra‐marker distance, total scan time and artifacts were evaluated for various combinations of echo time, repetition time, flip angle, number of excitations, bandwidth, slice thickness and spacing, fieldof‐ view, frequency/phase encoding steps and frequency direction.Results:We have developed a 3D FSPGR pulse sequence that enhances marker signal and ensures the integrity of the marker shape while maintaining reasonable scan time. For patients contraindicated for 3.0T, we have also developed a similar sequence for 1.5T scanners. Signal fall‐off with distance from prostate to coil can be compensated mainly by decreasing bandwidth. The markers are not visible using standard FSE sequences. FSPGR sequences are more robust for consistent marker visualization as compared to bSSFP sequences.Conclusion:The developed MRI pulse sequence protocol for Sirius MRI markers assists source localization to enable MRIonly post‐implant prostate dosimetric analysis.S.J. Frank is a co‐founder of C4 Imaging (manufactures the MRI markers).

Reduction of gray and white matters in patients with temporal lobe epilepsy and its correlation with disease duration

To measure the volumetric changes of gray and white matters in patients with temporal lobe epilepsy(TLE)using voxel-based morphometric study(VBM)and correlate the changes with clinical parameters. A total of 71 TLE patients were enrolled in the study,and 22 healthy subjects served as normal controls. Routine brain MRI and 3D fast spoiled gradient echo(FSPGR)T1-weighted images of all the subjects were acquired. The 3D structural images were co-registered,segmented and smoothed,and then the images were analyzed using the optimized VBM with preprocessed using Diffeomorphic Anatomical Registration using Exponentiated Lie algebra(DARTEL)algorithm. The global and local gray matter and white matter volume of each subject were calculated and compared between the TLE patients and normal controls. The potential correlations between the changes of the global and local gray and white matters in the TLE patients and the clinical parameters including the age at onset and the duration of epilepsy were explored. Compared to the normal controls,the TLE patients had diffuse volumetric reduction of gray and white matters in cerebrum both ipsilateral and contralateral to the seizure focus(P<0.05). Local gray matter reduction was found extensively in bilateral cerebral lobes,especially in the temporal and frontal lobes. Local white matter reduction was found in bilateral temporal,parietal and frontal lobes,in addition to the cingulate gyrus. The global gray matter volume(Global GMV)and the global white matter volume(Global WMV)were negatively correlated to the duration of epilepsy with the most significant change occurring in the first year of epilepsy. Global WMV dropped more quickly than Global GMV during the prolonged disease course. TLE patients have diffuse gray matter and white matter reduction,particularly in the early stage of epilepsy. The reduction of the white matter is more obvious than the gray matter.

Relationships of ultrasonographic and magnetic resonance image attributes to the histomorphology of ram testes

Declining male fertility has prompted investigations into the diagnostic methods that would permit frequent, non-invasive and accurate detection of changes in testicular histomorphology and the reproductive status of individuals. Ultrasonographic (U/S) and magnetic resonance (MR) imaging both have the potential to be used in this manner as associations have previously been described between the U/S and MR image attributes and histopathological changes in testicular tissue. The present study set out to determine if correlations exist between quantitative U/S and MR image attributes and histomorphological characteristics (total and luminal seminiferous tubule, ST area, and parenchymal cell density) of the excised ram testes, and to compare relative sensitivities of the imaging techniques. The echotextural/MR (input variables) and histological parameters (output variables) were analyzed by the Pearson's product moment correlations. Significant correlations were found for all imaging modalities, with the strongest overall correlation recorded for the T2 FAST SPIN ECHO (T2FSE) MR series (between mean numerical pixel values (NPVs) and total ST area; r=−0.93, p<0.001). The greatest number of significant correlations among quantitative image characteristics and histological attributes of testicular tissue were found for the 3 PLANE LOCALIZER (3 PLANE LOC) MR series, followed by the T2FSE MR, 3D FAST-SPOILED GRADIENT ECHO (3D FSPGRE) MR, U/S (7.5MHz) imaging, and finally T1 SPIN ECHO (T1SE) MR series. No significant correlations were recorded between the quantitative attributes of T1SE images and ST lumen area or parenchymal cell density, or between the attributes of the 3D FSPGRE images and cell density. We concluded that there existed a potential practical application for both U/S and MR image techniques, combined with computer-assisted image analysis, to monitor the changes in testicular histomorphology and male reproductive health and fertility. Scrotal U/S remains a first-line imaging technique for the assessment of male reproductive health due mainly to its versatility and lower cost.

MRI of the temporo-mandibular joint: which sequence is best suited to assess the cortical bone of the mandibular condyle? A cadaveric study using micro-CT as the standard of reference

To determine the best suited sagittal MRI sequence out of a standard temporo-mandibular joint (TMJ) imaging protocol for the assessment of the cortical bone of the mandibular condyles of cadaveric specimens using micro-CT as the standard of reference. Sixteen TMJs in 8 human cadaveric heads (mean age, 81 years) were examined by MRI. Upon all sagittal sequences, two observers measured the cortical bone thickness (CBT) of the anterior, superior and posterior portions of the mandibular condyles (i.e. objective analysis), and assessed for the presence of cortical bone thinning, erosions or surface irregularities as well as subcortical bone cysts and anterior osteophytes (i.e. subjective analysis). Micro-CT of the condyles was performed to serve as the standard of reference for statistical analysis. Inter-observer agreements for objective (r = 0.83-0.99, P < 0.01) and subjective (κ = 0.67-0.88) analyses were very good. Mean CBT measurements were most accurate, and cortical bone thinning, erosions, surface irregularities and subcortical bone cysts were best depicted on the 3D fast spoiled gradient echo recalled sequence (3D FSPGR). The most reliable MRI sequence to assess the cortical bone of the mandibular condyles on sagittal imaging planes is the 3D FSPGR sequence. MRI may be used to assess the cortical bone of the TMJ. • Depiction of cortical bone is best on 3D FSPGR sequences. • MRI can assess treatment response in patients with TMJ abnormalities.