Significant Difference In SNR Research Articles

Deep Learning-Based Super-Resolution Reconstruction on Undersampled Brain Diffusion-Weighted MRI for Infarction Stroke: A Comparison to Conventional Iterative Reconstruction.

DWI is crucial for detecting infarction stroke. However, its spatial resolution is often limited, hindering accurate lesion visualization. Our aim was to evaluate the image quality and diagnostic confidence of deep learning (DL)-based super-resolution reconstruction for brain DWI of infarction stroke. This retrospective study enrolled 114 consecutive participants who underwent brain DWI. The DWI images were reconstructed with 2 schemes: 1) DL-based super-resolution reconstruction (DWIDL); and 2) conventional compressed sensing reconstruction (DWICS). Qualitative image analysis included overall image quality, lesion conspicuity, and diagnostic confidence in infarction stroke of different lesion sizes. Quantitative image quality assessments were performed by measurements of SNR, contrast-to-noise ratio (CNR), ADC, and edge rise distance. Group comparisons were conducted by using a paired t test for normally distributed data and the Wilcoxon test for non-normally distributed data. The overall agreement between readers for qualitative ratings was assessed by using the Cohen κ coefficient. A P value less than .05 was considered statistically significant. A total of 114 DWI examinations constituted the study cohort. For the qualitative assessment, overall image quality, lesion conspicuity, and diagnostic confidence in infarction stroke lesions (lesion size <1.5 cm) improved by DWIDL compared with DWICS (all P < .001). For the quantitative analysis, edge rise distance of DWIDL was reduced compared with that of DWICS (P < .001), and no significant difference in SNR, CNR, and ADC values (all P > .05). Compared with the conventional compressed sensing reconstruction, the DL-based super-resolution reconstruction demonstrated superior image quality and was feasible for achieving higher diagnostic confidence in infarction stroke.

Use of Low Melting Point Alloy Mcp-96 Filter on Gammagraphic Optimization of Patient Position Verification with Telecobalt 60 Machine

Verification of the patient's position is a stage in external radiotherapy that aims to ensure the accuracy of radiation therapy administration according to plan. Equipment for the patient position verification process that is often used is Electronic Portal Image Devices (EPID) and film portals. However, not all Telecobalt 60 machines are equipped with EPID, so it requires alternative equipment to verify patient positions. One modality that can be utilized is Computed Radiography (CR). The study was conducted to analyze the use of MCP-96 low melting point alloy filters in imaging, verifying patient positions with CR devices on telecobalt 60 machine can calibrate radiation doses and provide good image quality and anatomical information. The study used a posttest-only control group design by comparing radiation dose, image quality, and anatomical information of the patient's position verification image. Imaging was performed using a phantom pelvis as an object and using CR equipment and low melting point alloy MCP-96 as a filter. The results showed that low melting points alloy MCP-96 with a thickness of 1 cm, 2 cm and 4 cm can calibrate the radiation dose output of the telecobalt 60 machine in accordance with recommendations for kilovoltage imaging. There was no significant difference in SNR and CNR images from imaging verification of patient positions with filter thicknesses of 1 cm, 2 cm, and 4 cm. Filter thickness of 1 cm produces images with optimal image quality and anatomical information in gammagraphic imaging verification of patient position using CR on telecobalt 60 machine. Thus, the use of low melting point alloy MCP-96 thickness of 1 cm and CR devices can be used in gammagraphic imaging of patient position verification on a telecobalt 60 machine as an alternative if you do not have EPID.

Functional Magnetic Resonance Urography in Children-Tips and Pitfalls.

MR urography can be an alternative to other imaging methods of the urinary tract in children. However, this examination may present technical problems influencing further results. Special attention must be paid to the parameters of dynamic sequences to obtain valuable data for further functional analysis. The analysis of methodology for renal function assessment using 3T magnetic resonance in children. A retrospective analysis of MR urography studies was performed in a group of 91 patients. Particular attention was paid to the acquisition parameters of the 3D-Thrive dynamic with contrast medium administration as a basic urography sequence. The authors have evaluated images qualitatively and compared contrast-to-noise ratio (CNR), curves smoothness, and quality of baseline (evaluation signal noise ratio) in every dynamic in each patient in every protocol used in our institution. Quality analysis of the image (ICC = 0.877, p < 0.001) was improved so that we have a statistically significant difference in image quality between protocols (χ2(3) = 20.134, p < 0.001). The results obtained for SNR in the medulla and cortex show that there was a statistically significant difference in SNR in the cortex (χ2(3) = 9.060, p = 0.029). Therefore, the obtained results show that with the newer protocol, we obtain lower values of standard deviation for TTP in the aorta (in ChopfMRU: first protocol SD = 14.560 vs. fourth protocol SD = 5.599; in IntelliSpace Portal: first protocol SD = 15.241 vs. fourth protocol SD = 5.506). Magnetic resonance urography is a promising technique with a few challenges that arise and need to be overcome. New technical opportunities should be introduced for everyday practice to improve MRU results.

Analysis of image quality by regulating beta function of BSREM reconstruction algorithm and comparison with conventional reconstructions in carcinoma breast studies of PET CT with BGO detector.

The study aimed to evaluate the beta penalization factor of the BSREM reconstruction algorithm on a five-ring BGO-based PET CT system and compared it with conventional reconstructions. Retrospective study involves 30 breast cancer patient data of 18F-fluorodeoxyglucose ( 18 F-FDG) PET CT for reconstruction with OSEM, OSEM + PSF, and BSREM under variable β factors ranging from 200 to 600 in the steps of 50. Liver noise, lesion SUVmax, SBR, and SNR for each reconstruction were calculated. Quantitative parameters of each beta factor of BSREM were compared with OSEM and OSEM + PSF, using the Wilcoxon sign rank test with Bonferroni correction, a value of P < 0.002 was considered statistically significant. Visual scoring by two readers was also evaluated. Thirty lesions of mean size 1.91 ± 0.58 cm range (0.7-3.6 cm) were identified. Liver noise and SBR were reduced, whereas SNR was increased with an increasing β value of BSREM. In comparison with OSEM, liver noise was not significantly different from β200 and β250. SNR of OSEM was significantly lower than any other β factors and SBR of β factor less than 500 was significantly higher than OSEM. In comparison with OSEM + PSF, liver noise was not significantly different from β400 and β350-500 do not show a significant difference in SNR and SBR compared with OSEM + PSF. β350 scored highest under visual scoring with a moderate agreement. The study quantitatively indicates the optimum beta range of β250-450 and the qualitative evaluation indicates that β350 is an optimum beta factor of BSREM in breast cancer cases for 18 F-FDG WB-PET CT.

Feasibility of deep learning k-space-to-image reconstruction for diffusion weighted imaging in patients with breast cancers: Focus on image quality and reduced scan time

PurposeThis study aimed to evaluate the feasibility of accelerated DLR (deep learning reconstruction) single-shot echo planar imaging (ss-EPI) for diffusion-weighted image (DWI) in patients with breast cancers in comparison to conventional ss-EPI. MethodsBetween August 2021 and February 2022, eighty-seven patients with pathologically proven breast cancer underwent DCE breast MRI including ss-EPI and DLR ss-EPI DWI sequences (TA, 3:36 min and 1:54 min, respectively) at 3 Tesla. In a randomized and blinded manner, two radiologists independently performed qualitative analyses for overall image quality using a 5-point scale of the following components: homogeneous fat suppression, image blurring, artifact, and lesion conspicuity. Quantitative analyses were performed by measurement of ADC values, SNR, CNR, and lesion contrast. ResultsDLR ss-EPI showed better image quality scores, CNR, and lesion contrast than ss-EPI (all P < 0.05) while reducing scan time by 47.2 %. DLR ss-EPI showed no significant difference in SNR and tumor ADC values compared to –ss-EPI (P = 0.307 and P = 0.123, respectively). ConclusionsDLR ss-EPI showed better results in the qualitative and quantitative analysis than conventional ss-EPI despite reducing scan time by 47.2%.

Utilizing flip angle/TR equivalence to reduce breath hold duration in hyperpolarized 129 Xe 1-point Dixon gas exchange imaging.

To reduce scan duration in hyperpolarized 129 Xe 1-point Dixon gas exchange imaging by utilizing flip angle (FA)/TR equivalence. Images were acquired in 12 subjects (n = 3 radiation therapy, n = 1 unexplained dyspnea, n = 8 healthy) using both standard (TR = 15 ms, FA = 20°, duration = 15 s, 998 projections) and "fast" (TR = 5.4 ms, FA = 12°, duration = 11.3 s, 2100 projections) acquisition parameters. For the fast acquisition, 3 image sets were reconstructed using subsets of 1900, 1500, and 1000 projections. From the resulting ventilation, tissue ("barrier"), and red blood cell (RBC) images, image metrics and biomarkers were compared to assess agreement between methods. Images acquired using both FA/TR settings had similar qualitative appearance. There were no significant differences in SNR, image mean, or image SD between images. Moreover, the percentage of the lungs in "defect", "normal", and "high" bins for each image (ventilation, RBC, barrier) was not significantly different among the acquisition types. After registration, comparison of 3D image metrics (Dice, volume similarity, average distance) agreed well between bins. Images using 1000 projections for reconstruction had no significant differences from images using all projections. Using flip angle/TR equivalence, hyperpolarized 129 Xe gas exchange images can be acquired via the 1-point Dixon technique in as little as 6 s, compared to ~15 s for previously reported parameter settings. The resulting images from this accelerated scan have no significant differences from the standard method in qualitative appearance or quantitative metrics.

A Study on the Use of High Density Polyethylene Masks to Prevent Respiratory Infection in Magnetic Resonance Imaging

In this study, a high-density polyethylene (HDPE) nose wire was applied to a mask and then used during magnetic resonance imaging (MRI) examination to measure the change in SNR and evaluate satisfaction level. A phantom was used to measure SNR before and after the application of the HDPE mask, and to measure SNR before and after the application of a KF 94 mask. The techniques used were T1WI, T2WI, and DWI. In addition, after obtaining T2 mDixon and 3D T1 images of the HDPE mask group, SNR of the orbit and pons were measured and the degree of tightness and ease of breathing during the MRI examination were evaluated. The preference for the HDPE mask was assessed through a survey. The result of the phantom test showed that there was no significant difference in SNR before and after using the HDPE mask (p>0.05). However, results showed that there was a significant difference when using the KF 94 mask (p 0.05). The result of measuring the degree of tightness after wearing a mask showed that the wearing group and the non-wearing group had 3.53 ± 0.73 and 3.83 ± 0.75, respectively. Also, the result of measuring the ease of breathing was 3.10 ± 0.89 in the HDPE mask-wearing group, and 3.27 ± 0.91 in the non-wearing group and both findings showed no significant difference (p>0.05). The preference for the HDPE mask was 4.48 ± 0.54, indicating a high preference. The results of this study showed that the HDPE mask can be used without causing any signal change in the MRI images, and that patient satisfaction was high. Therefore, HDPE masks should be used to prevent respiratory infections during the examination.

The Influence of Alteration of kVp and mAs towards the Image Quality of Acrylic Using CBCT

CBCT is a modernized technology in producing radiograph image on dentistry. The image quality excellence is very important for clinicians to interpret the image, so the result of diagnosis produced becoming more accurate, appropriate, thus minimizing the working time. This research was aimed to assess the image quality using the blank acrylic phantom polymethylmethacrylate (PMMA) (C­5H8O2)n in the density of 1.185 g/cm3 for evaluating the homogeneity and uniformity of the image produced. Acrylic phantom was supported with a tripod and laid down on the chin rest of the CBCT device, then the phantom was fixed, and the edge of the phantom was touched by the bite block. Furthermore, the exposure of the X-ray was executed toward the acrylic phantom with various kVp and mAs, from 80 until 90, with the range of 5 kV and the variation of mA was 3, 5, and 7 mA respectively. The time exposure was kept constant for 25 seconds. The samples were taken from CBCT acrylic images, then as much as 5 ROIs (Region of Interest) was chosen to be analyzed. The ROIs determination was analyzed by using the ImageJ® software for recognizing the influence of kVp and mAs towards the image uniformity, noise and SNR. The lowest kVp and mAs had the result of uniformity value, homogeneity and signal to noise ratio of 11.22; 40.35; and 5.96 respectively. Meanwhile, the highest kVp and mAs had uniformity value, homogeneity and signal to noise ratio of 16.96; 26.20; and 5.95 respectively. There were significant differences between the image uniformity and homogeneity on the lowest kVp and mAs compared to the highest kVp and mAs, as analyzed with the ANOVA statistics analysis continued with the t-student post-hoc test with α = 0.05. However, there was no significant difference in SNR as analyzed with the ANOVA statistic analysis. The usage of the higher kVp and mAs caused the improvement of the image homogeneity and uniformity compared to the lower kVp and mAs.

DESIGN OF MODIFICATION EQUIPMENT TOOLS INVESTIGATION MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY PEDIATRIC PATIENTS IN HOSPITAL SANTO BORROMEUS BANDUNG

Background : On examination MRCP patient pediatric in Radiology Hospital Santo Borromeus using tools made of PVC. But the use of such aids has a deficiency, ie the size is too large so that there is a distance between objects to be checked with body coils that can reducing value of the signal generated. The purpose of this research is to know the design of equipment tools investigation MRCP pediatric examination, difference of image quality and anatomical information resulting from the use of standard hospital aids and modification aids. Methods : This research is a quantitative research with experimental approach to design of modification aids in water phantom and patient pediatric examination MRCP sequence T2 FRFSE axial. The test was performed on image quality that was statistically analyzed by paired T test using SPSS 22. Beside that, the test was also conducted on anatomy information which was assessed by 2 radiologists with qualitative assessment. Results : The results of this study there are significant differences in SNR between the use of standard hospital aids and modification tools with p value 0.001. CNR differences were also significant between the use of standard hospital aids and modification aids with p value 0.001 (p <0.05). Conclusion : The results of image quality and anatomical information showed the best results in the use of tools modifications.

Evaluation of prospective motion correction of high-resolution 3D-T2-FLAIR acquisitions in epilepsy patients

T2-FLAIR is the single most sensitive MRI contrast to detect lesions underlying focal epilepsies but 3D sequences used to obtain isotropic high-resolution images are susceptible to motion artefacts. Prospective motion correction (PMC) – demonstrated to improve 3D-T1 image quality in a pediatric population – was applied to high-resolution 3D-T2-FLAIR scans in adult epilepsy patients to evaluate its clinical benefit. Coronal 3D-T2-FLAIR scans were acquired with a 1mm isotropic resolution on a 3T MRI scanner. Two expert neuroradiologists reviewed 40 scans without PMC and 40 with navigator-based PMC. Visual assessment addressed six criteria of image quality (resolution, SNR, WM-GM contrast, intensity homogeneity, lesion conspicuity, diagnostic confidence) on a seven-point Likert scale (from non-diagnostic to outstanding). SNR was also objectively quantified within the white matter. PMC scans had near-identical scores on the criteria of image quality to non-PMC scans, with the notable exception that intensity homogeneity was generally worse. Using PMC, the percentage of scans with bad image quality was substantially lower than without PMC (3.25% vs. 12.5%) on the other five criteria. Quantitative SNR estimates revealed that PMC and non-PMC had no significant difference in SNR (P=0.07). Application of prospective motion correction to 3D-T2-FLAIR sequences decreased the percentage of low-quality scans, reducing the number of scans that need to be repeated to obtain clinically useful data.

Accuracy of gadoteridol enhanced MR-angiography in the evaluation of carotid artery stenosis

To compare image quality and diagnostic performance of Gadoteridol-enhanced MR angiography (MRA) with Gadobutrol-enhanced MRA in the evaluation of carotid artery stenosis. MRA was performed in 30 patients with carotid stenosis diagnosed at DUS. Patients were randomly assigned to group A (Gadobutrol-enhanced MRA) or group B (Gadoteridol-enhanced MRA). All examinations were performed with a 3T MR system. Image quality was assessed qualitatively by a 3-grade scale and quantitatively with SNR measurements. Diagnostic performance in the assessment of stenosis, plaque length and morphology was evaluated in the two MRA groups by accuracy calculation and RoC curves analysis using CTA as reference standard. Statistically significant differences in SNR and quality scale were evaluated by the Independent-Samples T Test and Mann–Whitney test, while the Z-statistics was used to compare diagnostic accuracy in the two groups. Image quality was graded adequate to excellent for both GBCAs, without significant differences (p = 0.165). SNR values were not significantly different in group B (Gadoteridol-enhanced MRA) as compared to group A (Gadobutrol-enhanced MRA) (89.32 ± 70.4 vs 81.09 ± 28.38; p = 0.635). Diagnostic accuracy was 94 % for the evaluation of stenosis degree and 94 % for the identification of ulcerated plaques in group A, while it was 93 % for the evaluation of stenosis degree and 76 % for the identification of ulcerated plaques in group B, without statistically significant differences (p = 0.936). No significant difference in terms of image quality and diagnostic accuracy was observed between Gadoteridol-enhanced MRA and Gadobutrol-enhanced MRA in patients undergoing evaluation of carotid stenosis.

Optimalisasi Informasi Citra T1 W1 Post-Contrast Dengan Fat Saturation dan Pengaturan Time Repetition: Studi pada Pemeriksaan Magnetic Resonance Imaging Brain dengan Kasus Tumor

Background: Fat saturation is an alternative technique to improve image information in T1 WI post contrast MRI of brain tumor. It can increase lesion conspituity by suppressing normal tissue’s signal. To optimize image information by using fat saturation, selection of Fat Saturation type and Time Repetition (TR) value are important.Objectives: to analyze the differences in T1 WI post-contrast image information in MRI of brain tumor in various type of Fat Saturation and TR value.Methods: Experimental study with factorial design conducted in Telogorejo Hospital-Semarang. Nine combinations (9 groups) of three Fat Saturation types (none, weak, and strong) by three TR values (700 ms, 750 ms, and 800 ms) were given to 12 patients of MRI brain tumor. Image informations were assessed by measuring SNR (white matter, gray matter, lesions, surrounding tissue), CNR (white matter- gray matter, white matter-CSF, gray matter-CSF, lesion- surrounding tissue), lesion conspituity, artifacts, and contrast image in general.Results: The results showed that there were significant differences in SNR of white matter, gray matter, and in surrounding tissue (p 0.05); CNR of white matter-CSF, gray matter-CSF, lesion-tissue surrounding tissue (p 0.05); and lesion conspituity (p 0.05) between groups with no sat fat, weak fat sat, and strong fat sat. There were significant differences in SNR of white matter, gray matter, and surrounding tissue (p 0.05); and CNR of white matter-CSF, gray matter-CSF, and lesion- surrounding tissue (p 0.05) between group TR 700 ms, TR 750 ms, and TR 800 ms.Conclusion: Combination of strong fat saturation and TR 700 ms can produce the most optimal image information.

Evaluation of automated attenuation-based tube potential selection in combination with organ-specific dose reduction for contrast-enhanced chest CT examinations

To evaluate the influence of attenuation-based tube potential selection (ATPS) in combination with organ-specific dose reduction (OSDR) on radiation dose and image quality of contrast-enhanced chest computed tomography (CT) examinations. Seventy consecutive patients (59.2±16.1 years; 49 men; 21 women) were randomized into two groups and underwent contrast-enhanced chest CT using a 128 section CT scanner. CT examinations were performed as standard protocol in group A (n=35) and with the activated novel dose-saving devices, OSDR and ATPS, in group B (n=35). Objective [signal-to-noise (SNR) and contrast-to-noise ratio (CNR)] and subjective image quality (five-point scale; 1=non diagnostic; 5=excellent) as well as radiation dose (CTDIvol) were analysed. CTDIvol of the protocol using OSDR and ATPS was significantly lower than in standard chest CT examinations (3.4±1 versus 6.1±2.3mGy; p<0.001). Although the level of noise was slightly elevated in group B (14.1±1.7 versus 11.4±1.9HU; p<0.01), no significant differences in SNR (17.1±5 versus 16.3±4.7) or subjective image quality (mean score of 4.6 versus 4.4) were observed between both imaging protocols. Attenuation-based tube potential selection in combination with organ-specific dose reduction essentially reduces the dose of chest CT in patients with normal body mass index (BMI) in clinical routine while maintaining subjective and objective image quality.

Comparison of Self-Gated and Prospectively Triggered Fast Low Angle Shot (FLASH) Sequences for Contrast-Enhanced Magnetic Resonance Imaging of the Liver at 9.4 T in a Rat Model of Colorectal Cancer Metastases

The aim of this study was to compare a retrospectively self-gated fast low angle shot sequence (RSG-FLASH) with a prospectively triggered fast low angle shot sequence (PT-FLASH) using an external trigger device for dynamic contrast-enhanced magnetic resonance imaging of the liver at 9.4 T in a rat model of colorectal cancer metastases. In 10 rats with hepatic metastases, we acquired an axial RSG-FLASH sequence through the liver. A FLASH sequence with prospective triggering (PT-FLASH) using an external trigger device was acquired at the same location with the same imaging parameters. After intravenous injection of 0.2 mmol/kg body weight of Gd-DTPA, alternating acquisitions of both sequences were performed at 4 consecutive time points.Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and lesion enhancement were obtained for liver tumors and parenchyma. In addition, we assessed the total acquisition times of the different imaging approaches for each acquisition, including triggering and gating. Two independent readers performed a qualitative evaluation of each sequence. Statistical analyses included paired t tests and Wilcoxon matched pairs signed rank tests. No statistically significant differences in SNR, CNR, or lesion enhancement were observed. Qualitative assessments of the sequences were comparable. However, acquisition times of PT-FLASH were significantly longer (mean [SD], 160.6 [25.7] seconds; P < 0.0001) and markedly variable (minimum, 120 seconds; maximum, 209 seconds), whereas the RSG-FLASH approach demonstrated a constant mean (SD) acquisition time of 59.0 (0) seconds. The RSG-FLASH and PT-FLASH sequences do not differ qualitatively or quantitatively regarding SNR, CNR, and lesion enhancement for magnetic resonance imaging of the liver in the rats at 9.4 T. However, the variability of acquisition times for the PT-FLASH sequences is a major factor of inconsistency, and we therefore consider this approach as inappropriate for dynamic contrast-enhanced studies with multiple-measurement time points. In contrast, the RSG-FLASH sequence represents a fast, consistent, and reproducible technique suitable for contrast-agent kinetic studies in experimental small-animal imaging of the abdomen.

Impact of Field Strength and Respiratory Motion Control on Diffusion-Weighted MR Imaging of the Liver

Purpose: To evaluate the impact of field strength and respiratory motion control on diffusion-weighted MR imaging (DWI) of the liver at 1.5 and 3 T. Material and Methods: Three DWI sequences using seven b-values from 20 - 400 s/mm2 were designed with identical parameters but with different handling of respiratory motion [respiratory triggered (RT), free breathing (FB), breath hold (BH)] on 3 T and 1.5 T. Thirteen volunteers were examined at a 3 T and six of them also at a 1.5 T magnet. DW images were analyzed quantitatively and qualitatively. Regions of interest were placed in cranial, middle and caudal parts of the right liver lobe (RLL) and ADC and SNR were calculated. Results: ADC in RLL tended to be lower at 3 T MRI. Least inter-subject ADC variability was found with RT in the middle RLL at 3 T. Highest ADCs were found caudally in the RLL. Significant differences in ADC between middle and caudal RLL were calculated in FB and RT at 3 T and FB and BH at 1.5 T, respectively. No significant difference in SNR was found between 3 T and 1.5 T. There were significantly more artifacts in the left liver lobe (LLL) compared to the RLL in all sequences and in the LLL at 3 T compared to 1.5 T. Conclusion: Our study suggests that longitudinal hepatic ADC measurements should be performed using equivalent field strength, b-values, and acquisition technique, given influence of these factors on ADC measurements.

Free-breathing dynamic contrast-enhanced MRI of the abdomen and chest using a radial gradient echo sequence with K-space weighted image contrast (KWIC)

To evaluate the feasibility of free-breathing, dynamic contrast-enhanced (DCE) MRI of the abdomen and thorax using the radial-gradient-echo sequence with k-space weighted image contrast (KWIC) reconstruction. Institutional review board approval was obtained. Fourteen patients underwent free-breathing radial DCE-MRI. Radial MRI yielded full-frame images by gridding all k-space data and time-resolved subframe images by using KWIC reconstruction technique. Using subframe KWIC images, voxel-wise perfusion maps were created. For comparison, the breath-hold conventional Cartesian 3D-gradient-echo sequence (VIBE) was also performed during the equilibrium phase. The image qualities of radial and conventional VIBE images were compared quantitatively and qualitatively. Radial DCE-MRI provided high spatial resolution (1.4 × 1.4 mm) and temporal resolution (4.1 s for subframe images) allowing voxel-wise perfusion mapping with negligible motion or streaking artefacts. There were no significant differences in SNR between full-frame radial images and conventional VIBE images (79.08 vs 74.80, P > 0.05). Overall image quality score of full-frame radial images was slightly lower than that of conventional VIBE images (3.88 ± 0.59 vs. 4.31 ± 0.97, P < 0.05), but provided clinically useful images. The free-breathing radial DCE-MRI can provide high spatial and temporal resolution while maintaining reasonably high image quality and thus is a feasible technique for DCE-MRI in the abdomen and thorax. • Dynamic contrast-enhanced magnetic resonance imaging (DCE) MRI is important in oncological imaging • Radial MRI with k-space weighted image contrast (KWIC) reconstruction offers potential improvements • Radial DCE-MRI provides good image quality, reduced artefacts and high spatial/temporal resolution.

SU‐E‐I‐24: Determining the Optimal B‐Values to Use in Diffusion Weighted Imaging for Differentiating Benign and Malignant Breast Lesions

To investigate and determine the optimal b-values for Diffusion Weighted Imaging(DWI) for Apparent Diffusion Coefficient(ADC) maps in differentiating normal, benign and malignant breast tissue. Twenty-five patients underwent diffusion-weighted magnetic resonance imaging (DWI-MRI) and conventional breast MRI with suspicious breast fmdings(BIRADS >4). Breast lesions were defined by pathology. The DWI was acquired with different b-values ranging from 0,500, 600,750 and 1000s/mm2 . Apparent Diffusion Coefficient(ADC) maps of breast tissue were constructed using different b-values, e.g., using either 2 b-values(0- 1000) or combinations of 3 or more (0,500,1000 or 0,600,750,1000). Quantitative analyses of the ADC maps of glandular, fatty and lesion tissue were obtained. Ratios of lesion to glandular tissue(L/GT) and signal to noise(SNR) were assessed. Paired t-tests were performed for statistical significance. Eighteen patients had invasive ductal carcinoma and 7 had benign breast lesions. The mean ADC value for malignant lesions using all b values was 1.17±0.16×10-3mm2 /s with a lesion to glandular(L/GT) ratio=0.65. The benign lesions, ADC map value was 1.86±0.03×10-3mm2 /s with L/GT=0.98. There was a significant difference(P<0.05) between benign and malignant lesions ADC map value.The lowest SNR(12±6) was with single b-values. There was a significant difference(P<0.05) in SNR with multiple b-values(34±6) compared to single b-values. The highest SNR was given by using two b values greater than 500. Finally, the background noise for all combinations was surprising stable and ranged between 60±20%. This is the first study to investigate the effect of changing different b values in DWI breast imaging. There were significant differences in the SNR between single and multiple b values. Our data show suggest that the recommended b-values for DWI in breast are 0, and two that are 500 or greater. Therefore use of at least 3 b-values in DWI/ADC mapping of breast lesions are needed for better characterization of benign and malignant breast tissue. P50CA88843, Avon Foundation for Women:01-2008-012, U01CA070095, andU01CA140204.

High‐resolution ZTE imaging of human teeth

MRI with zero echo time (ZTE) is achieved by 3D radial centre-out encoding and hard-pulse RF excitation while the projection gradient is already on. Targeting short-T(2) samples, the efficient, robust and silent ZTE approach was implemented for high-bandwidth high-resolution imaging requiring particularly rapid transmit-receive switching and algebraic image reconstruction. The ZTE technique was applied to image extracted human teeth at 11.7T field strength, yielding detailed depictions with very good delineation of the mineralised dentine and enamel layers. ZTE results are compared with UTE (ultra-short echo time) MRI and micro-computed tomography (μCT), revealing significant differences in SNR and CNR yields. Compared to μCT, ZTE MRI appears to be less susceptible to artefacts caused by dental fillings and to offer superior sensitivity for the detection of early demineralisation and caries lesions.

Cranial CT with Adaptive Statistical Iterative Reconstruction: Improved Image Quality with Concomitant Radiation Dose Reduction

To safeguard patient health, there is great interest in CT radiation-dose reduction. The purpose of this study was to evaluate the impact of an iterative-reconstruction algorithm, ASIR, on image-quality measures in reduced-dose head CT scans for adult patients. Using a 64-section scanner, we analyzed 100 reduced-dose adult head CT scans at 6 predefined levels of ASIR blended with FBP reconstruction. These scans were compared with 50 CT scans previously obtained at a higher routine dose without ASIR reconstruction. SNR and CNR were computed from Hounsfield unit measurements of normal GM and WM of brain parenchyma. A blinded qualitative analysis was performed in 10 lower-dose CT datasets compared with higher-dose ones without ASIR. Phantom data analysis was also performed. Lower-dose scans without ASIR had significantly lower mean GM and WM SNR (P = .003) and similar GM-WM CNR values compared with higher routine-dose scans. However, at ASIR levels of 20%-40%, there was no statistically significant difference in SNR, and at ASIR levels of ≥60%, the SNR values of the reduced-dose scans were significantly higher (P < .01). CNR values were also significantly higher at ASIR levels of ≥40% (P < .01). Blinded qualitative review demonstrated significant improvements in perceived image noise, artifacts, and GM-WM differentiation at ASIR levels ≥60% (P < .01). These results demonstrate that the use of ASIR in adult head CT scans reduces image noise and increases low-contrast resolution, while allowing lower radiation doses without affecting spatial resolution.

Macrophage imaging by USPIO-enhanced MR for the differentiation of infectious osteomyelitis and aseptic vertebral inflammation

The purpose of this study was to prospectively evaluate USPIO-enhanced MR imaging for the differentiation of vertebral infectious osteomyelitis and sterile inflammation. Vertebral osteomyelitis and sterile vertebral inflammation were induced in two groups of six rabbits each. MRI examinations were performed including unenhanced and gadolinium-enhanced fat-saturated SE T1w sequences. Once endplate enhancement was observed on the T1 gadolinium-enhanced MR sequence, a second MRI examination (SE T1w sequence) was performed 24 h after USPIO administration (45 micromol Fe/kg). MR imaging was correlated with histopathological findings (macrophage immunostaining and Perls Prussian blue staining). On gadolinium-enhanced T1 sequences, a significant SNR increase in vertebral endplates was present in both groups without significant difference between the two groups (P = 0.26). On USPIO-enhanced T1 sequences, a significant SNR increase was only observed in the infection group (P = 0.03) with a significant difference in SNR between the infection and the sterile-inflammation groups (P = 0.002). Infected areas presented replacement of bone marrow by an intense macrophage infiltration, some being iron-loaded. Sterile inflammation showed a replacement of bone marrow by inflammatory tissue with only rare macrophages without any Perls blue staining. USPIO-enhanced MR imaging can distinguish infectious osteomyelitis from sterile vertebral inflammation due to different macrophage distributions in the two lesions.