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At least 289 records · Page 16Linked to original sources
PubMed2003

A wavelet-based approximation of surface coil sensitivity profiles for correction of image intensity inhomogeneity and parallel imaging reconstruction.

We evaluate a wavelet-based algorithm to estimate the coil sensitivity modulation from surface coils. This information is used to improve the image homogeneity of magnetic resonance imaging when a surface coil is used for reception, and to increase image encoding speed by reconstructing images from under-sampled (aliased) acquisitions using parallel magnetic resonance imaging (MRI) methods for higher spatiotemporal image resolutions. The proposed algorithm estimates the spatial sensitivity profile of surface coils from the original anatomical images directly without using the body coil for additional reference scans or using coil position markers for electromagnetic model-based calculations. No prior knowledge about the anatomy is required for the application of the algorithm. The estimation of the coil sensitivity profile based on the wavelet transform of the original image data was found to provide a robust method for removing the slowly varying spatial sensitivity pattern of the surface coil image and recovering full FOV images from two-fold acceleration in 8-channel parallel MRI. The results, using bi-orthogonal Daubechies 97 wavelets and other members in this family, are evaluated for T1-weighted and T2-weighted brain imaging.

Algorithms↗
PubMed2003

Fast T2-weighted MR imaging: impact of variation in pulse sequence parameters on image quality and artifacts.

The purpose of this study was to quantitatively evaluate in a phantom model the practical impact of alteration of key imaging parameters on image quality and artifacts for the most commonly used fast T(2)-weighted MR sequences. These include fast spin-echo (FSE), single shot fast spin-echo (SSFSE), and spin-echo echo-planar imaging (EPI) pulse sequences. We developed a composite phantom with different T1 and T2 values, which was evaluated while stationary as well as during periodic motion. Experiments involved controlled variations in key parameters including effective TE, TR, echo spacing (ESP), receive bandwidth (BW), echo train length (ETL), and shot number (SN). Quantitative analysis consisted of signal-to-noise ratio (SNR), image nonuniformity, full-width-at-half-maximum (i.e., blurring or geometric distortion) and ghosting ratio. Among the fast T(2)-weighted sequences, EPI was most sensitive to alterations in imaging parameters. Among imaging parameters that we tested, effective TE, ETL, and shot number most prominently affected image quality and artifacts. Short T(2) objects were more sensitive to alterations in imaging parameters in terms of image quality and artifacts. Optimal clinical application of these fast T(2)-weighted imaging pulse sequences requires careful attention to selection of imaging parameters.

Artifacts↗
PubMed2005

Prone SPECT myocardial perfusion imaging is associated with less cardiac drift during the acquisition duration than imaging in the supine position.

BACKGROUND AND AIM: Cardiac cranial drift, a slow vertical upward displacement seen during the acquisition of myocardial single photon emission tomography (SPECT), is a source of image artefacts that may lead to erroneous interpretation. Changes in breathing pattern and depth throughout image acquisition are believed to cause cardiac cranial drift. As the physiology of respiration probably differs with postural changes, we hypothesized that cardiac drift may be different for supine vs. prone acquisitions. Our aim was to assess the magnitude of cardiac displacement for prone and supine SPECT acquisitions in patients undergoing stress myocardial perfusion imaging. METHODS: We enrolled prospectively 15 subjects undergoing exercise myocardial perfusion imaging. Subjects had post-stress images acquired in both the prone and supine positions. Motion was assessed in the horizontal (x) and vertical (y) axes for both camera heads at all 64 projections at which images were obtained. Pixel displacement (number of pixels from the baseline of zero) in either the cranial/caudal or left/right direction was quantified using the automated camera motion correction algorithm. RESULTS: Supine imaging was associated with more cranial drift than prone imaging (1.20+/-0.40 pixels vs. 0.92+/-0.24 pixels, P<0.05). There was no significant difference in cardiac displacement in the horizontal axis (1.03+/-0.5 pixels vs. 1.12+/-0.22 pixels, P=NS). CONCLUSIONS: Prone imaging is associated with less cardiac cranial drift than imaging in the supine position, suggesting that the former is associated with a more constant and reliable diaphragmatic breathing pattern. Acquisitions in the prone position may thus be associated with fewer motion artefacts than supine acquisitions for cardiac SPECT imaging.

Adult↗
PubMed2003

Accurate quantification of right ventricular mass at MR imaging by using cine true fast imaging with steady-state precession: study in dogs.

PURPOSE: To assess the accuracy of cine magnetic resonance (MR) imaging with a segmented true fast imaging with steady-state precession (FISP) technique for right ventricular (RV) mass quantification. MATERIALS AND METHODS: Fourteen dogs were imaged with a 1.5-T clinical MR imaging unit by using an electrocardiographically gated true FISP sequence. Contiguous segmented k-space cine images were acquired from the base of the RV to the apex during suspended respiration (repetition time msec/echo time msec, 3.2/1.6; section thickness, 5 mm; in-plane resolution, 1.0 x 1.3 mm2). After imaging, each dog was sacrificed, and the RV free wall was isolated and weighed. Each MR imaging data set was analyzed twice by each of two independent observers who were blinded to the results of RV mass measurement at autopsy, and the mass measurements at MR imaging were compared with the autopsy results by using linear regression and Bland-Altman analysis. RESULTS: RV mass measurements calculated by using the true FISP cine MR images were nearly identical to those at autopsy (R = 0.82, standard error of the estimate = 1.7 g, P >.05), with a mean difference between the autopsy and MR imaging measurements of 0.3 g +/- 1.7 (1.9% +/- 8.2) (P >.05). Inter- and intraobserver variations were small, with a mean interobserver variability of -0.1 g +/- 2.3 and a mean intraobserver variability of 0.2 g +/- 1.6 at every-section analysis. CONCLUSION: In this animal model, true FISP cine MR imaging enabled accurate quantification of RV mass.

Animals↗
PubMed1998

Gadolinium-enhanced MR imaging of temporomandibular disorders: improved lesion detection of the posterior disk attachment on T1-weighted images obtained with fat suppression.

OBJECTIVE: The purpose of this study was to assess the potential for improved lesion detection in the posterior disk attachment and its surrounding tissue in temporomandibular disorders when gadolinium-enhanced MR imaging performed with fat suppression is used. MATERIALS AND METHODS: Forty-five patients underwent MR imaging with conventional T1- and T2-weighted, gadolinium-enhanced T1-weighted, and gadolinium-enhanced fat-suppressed spin-echo imaging sequences. Qualitative and quantitative assessments of the contrast enhancement of each type of imaging were also performed. RESULTS: The contrast-enhanced fat-suppressed T1-weighted imaging sequence had several advantages over the other imaging techniques in detecting abnormalities of the posterior disk attachment and in detecting bone marrow lesions in the mandibular condyle. The most significant advantage was better enhancement of lesion conspicuity. The diagnostic accuracy of contrast-enhanced fat-suppressed imaging was 77% versus 70% for conventional contrast-enhanced imaging. The kappa value for interobserver agreement was .95 for contrast-enhanced fat-suppressed imaging and .72 for conventional contrast-enhanced imaging. CONCLUSION: Contrast-enhanced fat-suppressed T1-weighted spin-echo MR imaging is a valuable technique for visualizing the extent and degree of lesions in the posterior disk attachment and bone marrow lesions in the mandibular condyle.

Adolescent↗
PubMed2006

Does high-field MR imaging have an influence on the classification of patients with clinically isolated syndromes according to current diagnostic mr imaging criteria for multiple sclerosis?

BACKGROUND AND PURPOSE: Current MR imaging criteria for multiple sclerosis (MS) do not specify the magnetic field strength. The aim of this study was to investigate whether different MR imaging field strengths, specifically high-field MR imaging, have an impact on the classification of patients with clinically isolated syndromes suggestive of MS, according to MR imaging and diagnostic criteria. METHODS: In a prospective intraindividual comparative study, we examined 40 patients with clinically isolated syndromes (CIS) consecutively with a 1.5 T and 3T MR imaging system, including axial sections of T2 turbo spin-echo, fluid-attenuated inversion recovery, and T1 spin-echo, before and after injection of gadolinium-diethylene-triaminepentaacetic acid. Constant resolution parameters were used for both field strengths. High-signal-intensity white matter lesions with a size of >3 mm were counted and categorized according to their anatomic location in infratentorial, callosal, juxtacortical, periventricular, and other white matter areas. Assessment of the fulfilled Barkhof MR imaging and McDonald diagnostic criteria was made separately for both field strengths in every patient. RESULTS: Eleven patients fulfilled more MR imaging criteria at 3T. Two of these patients fulfilled the criterion of dissemination in space (DIS) according to the first definition of McDonald criteria, which is based on imaging criteria alone. Another patient had DIS only at 3T, according to the second definition of the McDonald criteria including CSF parameters. CONCLUSION: MR field strength, specifically high-field MR imaging, has a substantial influence on the classification of patients with CIS according to imaging and a mild influence on the classification according diagnostic criteria for MS, leading to consequences for prognostic classification, imaging guidelines, and clinical trials.

Adolescent↗
PubMed2006

Animal-specific positioning molds for registration of repeat imaging studies: comparative microPET imaging of F18-labeled fluoro-deoxyglucose and fluoro-misonidazole in rodent tumors.

INTRODUCTION: Comparative imaging of multiple radiotracers in the same animal can be invaluable in elucidating and validating their respective mechanisms of localization. Comparative imaging of PET tracers, particularly in small animals, is problematic, however: such tracers must be administered and imaged separately because simultaneously imaged positron emitters cannot be separated based on energy discrimination. OBJECTIVE: As part of our ongoing development of hypoxia imaging radiotracers, the intratumoral distributions of sequentially administered F18-fluoro-deoxyglucose (FDG) and the hypoxia tracer F18-fluoromisonidazole (FMiso) were compared in rats by registered microPET imaging with positioning of each animal in a custom-fabricated whole-body mold. METHODS: Nude rats with a hindlimb R3327-AT anaplastic rat prostate tumor xenograft and a hindlimb FaDu human squamous cell carcinoma (each up to 20 x 20 x 30 mm in size) were studied. Rapid-Foam (Soule Medical, Lutz, FL) was used to fabricate animal-specific molds for immobilization and reproducible positioning. Each rat was injected via the tail vein with approximately 33 MBq (900 microCi) of FDG and imaged in its mold at 1 h postinjection (pi) on the microPET. The next day, each rat was injected with approximately 22 MBq (600 microCi) of FMiso and positioned and imaged in its mold at approximately 2 h pi. Custom-manufactured germanium-68 rods (10 microCi each, 1 x 10 mm) were reproducibly positioned in the mold as fiduciary markers. RESULTS: The registered microPET images unambiguously demonstrated grossly similar though not identical distributions of FDG and FMiso in the tumors - a high-activity rim surrounding a lower-activity core. There were subtle but possibly significant differences in the intratumoral distributions of FDG and FMiso, however. These may not have been discerned without careful image registration. CONCLUSION: Animal-specific molds are inexpensive and straightforward to fabricate and use for registration (+/-1 to 2 mm) of sequential PET images and may aid image interpretation.

Animals↗
PubMed2006

Dual optical and nuclear imaging in human melanoma xenografts using a single targeted imaging probe.

INTRODUCTION: Dual-labeled imaging agents that allow both nuclear and optical imaging after a single injection would be advantageous in certain applications. In this study, we synthesized and characterized a dual-labeled RGD (Arg-Gly-Asp) peptide and compared nuclear and optical images obtained with this agent. METHODS: 111In-DTPA-Lys(IRDye800)-c(KRGDf) composed of both the 111In chelator diethylenetriaminepentaacetic acid (DTPA) and the near-infrared (NIR) fluorescent dye IRDye800 (excitation/emission, 765/792 nm) was synthesized. The probe was characterized with regard to in vitro biological activity and in vivo pharmacokinetics and the ability to target integrin alphavbeta3. Tumors of mice injected with the dual-labeled probe were imaged both by gamma scintigraphy and NIR fluorescence optical camera. RESULTS: DTPA-Lys(IRDye800)-c(KRGDf), DTPA-Lys-c(KRGDf) and c(KRGDf) inhibited the adhesion of melanoma M21 cells to vitronectin-coated surface with the similar biological activity. Both 111In-DTPA-Lys(IRDye800)-c(KRGDf) and 111In-DTPA-Lys-c(KRGDf) had significantly higher uptakes in alphavbeta3-positive M21 melanoma than in alphavbeta3-negative M21-L melanoma at 4-48 h after their injection. Side-by-side comparison of images obtained using 111In-DTPA-Lys(IRDye800)-c(KRGDf) revealed that in living mice, both optical imaging and gamma scintigraphy enabled noninvasive detection of the bound probe to alphavbeta3-positive tumors, with optical images providing improved resolution and sensitive detection of the superficial lesions and gamma images providing sensitive detection of deeper structures. CONCLUSION: The dual-labeled imaging probe 111In-DTPA-Lys(IRDye800)-c(KRGDf) was found to specifically bind to alphavbeta3 in melanoma tumor cells. Employing both nuclear and optical imaging with a single imaging probe may facilitate translation of NIR fluorescence optical imaging into clinical applications.

Animals↗
PubMedDate not supplied

Benefits of reducing the cardiac cycle-triggering frequency of ultrasound imaging to increase myocardial opacification with FSO69 during fundamental and second harmonic imaging.

BACKGROUND: Recent work has shown significant enhancement in myocardial contrast intensity with brief ultrasound pulsing gated to a discrete portion of the cardiac cycle over conventional 30 Hz imaging. We hypothesized that limiting ultrasound imaging to less than every cardiac cycle would further intensity the myocardial echo-contrast effect. We therefore sought to determine the best pulsing frequency for ultrasound imaging to achieve optimal myocardial perfusion after the intravenous administration of FSO69 using fundamental and second harmonic imaging. METHODS AND RESULTS: In 13 male mongrel dogs, myocardial contrast opacification was determined while varying the cardiac cycle-triggering frequency of ultrasound imaging after intravenous injections of FSO69. Resulting myocardial echo-contrast intensities with a cardiac cycle-triggering frequency of every beat during end-diastole were compared with those with a cardiac cycle-triggering frequency of every third and fifth beat. Myocardial opacification, measured by background-subtracted peak intensity and visual scoring, was significantly greater when ultrasound imaging was triggered to every third and fifth beats compared with every beat. These benefits were seen with imaging in both the fundamental and second harmonic modes. Optimal myocardial opacification with FSO69 was achieved with injections as low as 0.1 ml, a dose that produced significant acoustic shadowing in only 24% of the injections. The degree of myocardial opacification was not significantly affected when the images were acquired during end-systole or end-diastole. CONCLUSIONS: Electrocardiogram-gated ultrasound imaging to every third or fifth cardiac cycle greatly improves myocardial opacification compared with imaging each cardiac cycle. This benefit was increased twofold to threefold with the use of second harmonic imaging as compared with fundamental imaging.

Albumins↗
PubMed2004

Is JPEG compression of videomicroscopic images compatible with telediagnosis? Comparison between diagnostic performance and pattern recognition on uncompressed TIFF images and JPEG compressed ones.

Early melanoma diagnosis is an important goal for dermatologists. Polarized light systems are increasingly employed for dermatoscopic diagnosis of melanocytic lesions. For the purpose of teledermoscopy, whose importance is increasingly growing for consultation and teaching purposes, it is of utmost importance to establish whether, after compression, polarized light images maintain their informativeness. The aim of our study was to check the effects of compression on melanocytic lesion images acquired by means of a digital videomicroscope on the identification of morphological details of the image and on diagnostic accuracy. A total of 170 50-fold-magnified pigmented skin lesion images, acquired in Tagged Image File Format (TIFF) by a digital videomicroscope, were compressed using Joint Photographic Experts Group (JPEG) algorithms (compression factor 30). Two experts in videomicroscopy evaluated both original and compressed images twice by describing single lesion features and expressing a diagnosis. Reproducibility in the assessment of dermoscopic parameters and observer performance were studied by kappa statistics and Receiver Operating Characteristic (ROC) analysis. Both intra- and interobserver reproducibility in the assessment of morphological details were higher when TIFF images were considered, indicating a better image quality. Nonetheless, there was no significant difference in the diagnostic accuracy between uncompressed images and compressed ones, although the intraobserver reproducibility in the diagnostic judgement was higher for uncompressed images. Despite loss in image details, factor 30 compressed videomicroscopic images enable a good diagnostic accuracy.

Algorithms↗
PubMedDate not supplied

Contrast in rapid MR imaging: T1- and T2-weighted imaging.

Partial saturation (PS) is an imaging technique that is useful in applications that require rapid image acquisitions (imaging time less than 1 min). Image contrast in PS imaging, as in other magnetic resonance methods, depends on the often conflicting effects of differences in proton density, T1, and T2. Previous analyses of pulse sequence optimization to maximize image contrast have assumed 90 degrees pulses and examined the effects of varying repetition times (TR) and echo times (TE). In this paper we present theoretical calculations and images made with a 0.6 T imager to show that the radiofrequency pulse tip angle alpha, and not the pulse sequence timing parameters, is the most important parameter for producing image contrast. For large tip angles (alpha greater than or equal to 60 degrees), contrast is primarily determined by differences in T1, but for small tip angles (alpha approximately equal to 25 degrees), contrast is primarily due to differences in T2. The T2-weighted images can be produced as quickly as T1-weighted images by using a small pulse angle and a long TE; it is not necessary to use a long TR to reduce the effects of T1 differences. Optimum pulse angles are calculated, and the potential advantages and disadvantages of T2-weighted and T1-weighted PS imaging are discussed.

Humans↗
PubMed2004

The addition of computer simulated noise to investigate radiation dose and image quality in images with spatial correlation of statistical noise: an example application to X-ray CT of the brain.

This study validates a method to add spatially correlated statistical noise to an image, applied to transaxial X-ray CT images of the head to simulate exposure reduction by up to 50%. 23 patients undergoing routine head CT had three additional slices acquired for validation purposes, two at the same clinical 420 mAs exposure and one at 300 mAs. Images at the level of the cerebrospinal fluid filled ventricles gave readings of noise from a single image, with subtraction of image pairs to obtain noise readings from non-uniform tissue regions. The spatial correlation of the noise was determined and added to the acquired 420 mAs image to simulate images at 340 mAs, 300 mAs, 260 mAs and 210 mAs. Two radiologists assessed the images, finding little difference between the 300 mAs simulated and acquired images. The presence of periventricular low density lesions (PVLD) was used as an example of the effect of simulated dose reduction on diagnostic accuracy, and visualization of the internal capsule was used as a measure of image quality. Diagnostic accuracy for the diagnosis of PVLD did not fall significantly even down to 210 mAs, though visualization of the internal capsule was poorer at lower exposure. Further work is needed to investigate means of measuring statistical noise without the need for uniform tissue areas, or image pairs. This technique has been shown to allow sufficiently accurate simulation of dose reduction and image quality degradation, even when the statistical noise is spatially correlated.

Aged↗
PubMed2002

Optical on-line running reconstruction of MR-images in the phase-scrambling Fourier-imaging technique.

Recently, the use of magnetic-resonance-guided navigation to improve the safety and effectiveness of surgical procedures has shown great promise. The purpose of the present study was to develop and demonstrate an imaging strategy that allows surgeons to continue operating without delays caused by imaging. The phase-scrambling Fourier-imaging technique has two prominent characteristics: localized image reconstruction and holographic image reconstruction. The combination of these characteristics allows images to be observed even during the data-acquisition period, because the acquired signal is converted into a hologram and the image is reconstructed instantly in the coherent optical image-processing system. Experimental studies have shown that the phase-scrambling Fourier-imaging technique enables the motion of objects to be imaged more quickly than the standard fast imaging. The proposed running reconstruction strategy can be easily implemented in the well-established magnetic-resonance imaging equipment that is currently in use.

Journal Article↗
PubMed2000

Breath-hold 3D gradient-echo MR imaging of the lung parenchyma: evaluation of reproducibility of image quality in normals and preliminary observations in patients with disease.

This study evaluates the reproducibility and image quality of a three-dimensional (3D) gradient-echo sequence for imaging the lung parenchyma, with and without gadolinium administration, using a 2D spoiled gradient-echo sequence for comparison. Twenty patients without lung disease (normals) and five patients with lung disease (lung disease) underwent paired 2D and 3D gradient-echo sequences, without contrast (24 patients) and with contrast (18 patients). Images were retrospectively reviewed independently in a blinded fashion by two investigators. Artifacts and demonstration of central lung, peripheral lung, heart, pulmonary arteries, and esophagus were evaluated. Image quality of the central lung was rated as fair or good in 5 and 4 (reader one and two) patients with non-contrast 2D gradient-echo, 24 and 25 patients with non-contrast 3D gradient-echo, 3 and 1 patient(s) with contrast-enhanced 2D gradient-echo, and 19 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in image quality between 2D and 3D sequences were significant (P < 0.001). Heart-related phase artifacts were negligible in 2 and 0 patients with non-contrast 2D gradient-echo, 23 and 25 patients with non-contrast 3D gradient-echo, 0 and 0 patients with contrast-enhanced 2D gradient-echo, and 17 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in heart-related phase artifact in the central lung between 2D and 3D sequences were significant (P = 0.001). Infiltrates, lung cancer, and pulmonary metastasis were better shown on the gadolinium-enhanced 3D gradient-echo sequences than on the other sequences. Breath-hold 3D gradient-echo imaging results in good image quality and negligible image artifacts and is superior to 2D spoiled gradient-echo imaging. Preliminary results in patients with disease appear promising.

Artifacts↗
PubMed2004

Echo planar MR imaging of the liver: comparison of images with and without motion probing gradients.

PURPOSE: To determine whether MR images with motion-probing gradients (MPGs) usefully improve lesion detection in comparison with MR images without MPGs. MATERIALS AND METHODS: Echo planar (EP) images without MPGs and with small and intermediate MPGs (gradient factor b = 2, 18, and 188 second/mm(2), respectively) were acquired for 61 hepatic lesions (21 hepatocellular carcinomas (HCCs), 19 metastases, eight hemangiomas, and 13 cysts). The lesion-to-liver signal intensity ratios (SIRs) of these lesions were calculated using EP images with and without MPGs. Qualitative analysis for detection of HCCs and metastases were also performed between the images without MPGs and with small MPGs. RESULTS: The SIRs of HCCs and metastases for the images with small MPGs were significantly higher than the values for the images without MPGs (P < 0.05), although no significant differences were found in the case of hemangiomas and cysts. In comparison to images without MPGs, images with small MPGs improved lesion detection of three metastases and six HCCs, and worsened lesion detection of two HCCs. CONCLUSION: Images with small MPGs may improve HCC and metastasis detection over images without MPGs.

Adult↗
PubMed1998

The Department of Veterans Affairs integration of imaging into the healthcare enterprise using the VistA Hospital Information System and Digital Imaging and Communications in Medicine.

The United States Department of Veterans Affairs is integrating imaging into the healthcare enterprise by using the Digital Imaging and Communication in Medicine (DICOM) standard protocols. Image management is directly integrated into the VistA Hospital Information System (HIS) software and clinical database. Radiology images are acquired with DICOM and are stored directly in the HIS database. Images can be displayed on low-cost clinician's workstations throughout the medical center. High-resolution diagnostic quality multimonitor VistA workstations with specialized viewing software can be used for reading radiology images. Two approaches are used to acquire and handle images within the radiology department. Some sites have a commercial Picture Archiving and Communications System (PACS) interfaced to the VistA HIS, whereas other sites use the direct image acquisition and integrated diagnostic display capabilities of VistA itself. A small set of DISCOM services has been implemented by VistA to allow patient and study text data to be transmitted to image producing modalities and the commercial PACS, and to enable images and study data to be transferred back. DICOM has been the cornerstone in the ability to integrate imaging functionality into the healthcare enterprise. Because of its openness, it allows the integration of system components from commercial and noncommercial sources to work together to provide functional cost-effective solutions.

Computer Communication Networks↗
PubMed1998

Radiologist evaluation of a multispectral image compression algorithm for magnetic resonance images.

With the advent of teleradiology and picture archiving and communication systems (PACS), the expense and time required for image transmission and long term image archiving become important. The use of validated image compression algorithms can greatly reduce these costs. A lossy, multispectral image compression scheme at compression ratios (CR) of 25:1 and 32:1 was used for a set of 26 different patient MR exams. The original and compressed/decompressed (CD) images sets were evaluated in a blinded fashion by four radiologists in two phases. The main objective was to determine whether radiologic interpretation would vary between the two types of CD image sets and the corresponding originals. In general, the compression algorithm caused a slight decrease in image quality; however, the interpretation of pathology did not change between the original and CD image sets. In only one case at the maximum CR = 32 did one of four radiologists change the interpretation of pathology after CD. In this study, lossy multispectral image compression of MR images at CR = 25 maintained diagnostic integrity. This could play a significant role in image storage and communications.

Algorithms↗
PubMed2005

Influence of high magnetic field strengths and parallel acquisition strategies on image quality in cardiac 2D CINE magnetic resonance imaging: comparison of 1.5 T vs. 3.0 T.

The aim of this paper is to examine signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and image quality of cardiac CINE imaging at 1.5 T and 3.0 T. Twenty volunteers underwent cardiac magnetic resonance imaging (MRI) examinations using a 1.5-T and a 3.0-T scanner. Three different sets of breath-held, electrocardiogram-gated (ECG) CINE imaging techniques were employed, including: (1) unaccelerated SSFP (steady state free precession), (2) accelerated SSFP imaging and (3) gradient-echo-based myocardial tagging. Two-dimensional CINE SSFP at 3.0 T revealed an SNR improvement of 103% and a CNR increase of 19% as compared to the results obtained at 1.5 T. The SNR reduction in accelerated 2D CINE SSFP imaging was larger at 1.5 T (37%) compared to 3.0 T (26%). The mean SNR and CNR increase at 3.0 T obtained for the tagging sequence was 88% and 187%, respectively. At 3.0 T, the duration of the saturation bands persisted throughout the entire cardiac cycle. For comparison, the saturation bands were significantly diminished at 1.5 T during end-diastole. For 2D CINE SSFP imaging, no significant difference in the left ventricular volumetry and in the overall image quality was obtained. For myocardial tagging, image quality was significantly improved at 3.0 T. The SNR reduction in accelerated SSFP imaging was overcompensated by the increase in the baseline SNR at 3.0 T and did not result in any image quality degradation. For cardiac tagging techniques, 3.0 T was highly beneficial, which holds the promise to improve its diagnostic value.

Adult↗