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Background It has often been argued that if patients' success with speech rehabilitation after laryngectomy is limited, it is the result of lacking motivation on their part. This project investigated the role of motivation in speech rehabilitation. Methods In a multicenter prospective cohort study, 141 laryngectomees were interviewed at the beginning of rehabilitation and 1 year after laryngectomy. Speech intelligibility was measured with a standardized test, and patients self-assessed their own motivation shortly after the surgery. Logistic regression, adjusted for several theory-based confounding factors, was used to assess the impact of motivation on speech intelligibility. Results Speech intelligibility 1 year after laryngectomy was not significantly associated with the level of motivation at the beginning of rehabilitation (odds ratio [OR], 1.3; 95% confidence interval [CI], 0.7-2.3; p = .43) after adjusting for the effect of potential confounders (implantation of a voice prosthesis, patient's cognitive abilities, frustration tolerance, physical functioning, and type of rehabilitation). Conclusions Motivation is not a strong predictor of speech intelligibility 1 year after laryngectomy. © 2012 Wiley Periodicals, Inc. Head Neck, 2012 [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to demonstrate the feasibility of cranial nerve (CN II-XII) imaging with 7 Tesla magnetic resonance imaging (MRI). Methods: In this study four sequences were evaluated in three healthy volunteers using magnetization preparation rapid gradient echo (MPRAGE), constructive interference in steady state (CISS), true fast imaging with steady state precession (TrueFISP) and proton density (PD) T2-weighted turbo spin echo (TSE) sequences. Results: It was found that MPRAGE did not always provide sufficient contrast to delineate in particular small CNs but displayed an overall good identification rate. The T2 sequence was not able to adequately differentiate the small CNs but showed a very good contrast between nerves and cerebrospinal fluid (CSF). As at lower magnetic fields steady state sequences displayed a high identification rate of all CNs in the axial plane but CISS suffered from susceptibility and pulsation artifacts, furthermore it was limited as no parallel imaging could be performed. The TrueFISP technique was reliable in identifying most CNs although suffering from banding artifacts. Conclusions: The TrueFISP sequence showed superior spatial resolution and contrast in comparison to the other sequences for imaging of CNs at 7 T. [ABSTRACT FROM AUTHOR]

Background: To obtain information on affected vessels in moyamoya disease (MMD), we analyzed the vascular morphological characteristics of MMD using three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance imaging (MRI). Methods: The population of this 3D-CISS MRI study consisted of 51 patients with MMD: 16 patients with atherosclerotic middle cerebral artery (MCA) stenosis or occlusion, 42 MRI control patients, and 28 control digital subtraction angiography (DSA) patients. We measured the outer diameters of the terminal portion of the internal carotid artery (ICA) and the proximal portion of the MCA (M1 portion). We evaluated the inner diameter as the relative value (%) obtained from magnified DSA images and analyzed these data. Results: The outer diameters of the ICA and M1 portions were significantly smaller in the MMD group than in the other two groups, while the M1 outer diameter of the atherosclerosis group was not significantly different compared to the control (ICA: MMD, 2.61 ± 0.46 mm vs. control, 4.04 ± 0.50 mm and M1: MMD, 1.92 ± 0.43 mm vs. control, 3.34 ± 0.54 mm vs. atherosclerosis, 3.45 ± 0.56 mm). Furthermore, in MMD patients, the outer diameter was unrelated to the progression of the luminal stenosis grade estimated by DSA. Conclusions: This is the first report that the outer diameters of both the ICA and M1 decrease in MMD patients. Our findings suggest that the vascular constrictive changes of the affected arteries are an important phenomenon reflecting MMD pathology. [ABSTRACT FROM AUTHOR]

Objectives: We examined the association between the size and cross-sectional area of the superior vestibular nerve as measured on constructive interference in steady-state (CISS) parasagittal magnetic resonance imaging (MRI) and the vestibular nerve function as measured by electronystagmography. Methods: The retrospective observational cohort study took place at an academic tertiary referral center. Twenty-six patients who met established clinical and electronystagmographic criteria for vestibular neuritis and who underwent parasagittal CISS MRI were identified. Two blinded investigators measured vestibular nerve height and width bilaterally at the level of the fundus of the internal auditory canal and calculated the cross-sectional nerve areas. The inter-rater reliability and agreement were analyzed. Symptom duration, age, and gender were also examined. Results: A statistically significant decrease was observed in both vestibular nerve cross-sectional area and height as compared to the contralateral vestibular nerve. A non-statistically significant trend was observed for a relative decreased cross-sectional nerve area with increased age, as well as a decrease in nerve area with an increase in symptom duration. Conclusions: Decreases in both vestibular nerve cross-sectional area and height are observed in patients with unilateral vestibular neuritis as measured on parasagittal CISS MRI. [ABSTRACT FROM AUTHOR]

A number of neuropathological studies have demonstrated that the olfactory system is among the first brain regions affected in Parkinson's disease (PD). These findings correlate with pathophysiological and pathological data that show a loss in olfactory bulb (OB) volume in patients with PD. However, to date, MRI has not been a reliable method for the in vivo detection of this volumetric loss in PD. Using a 3.0-Tesla MRI constructive interference in the steady-state sequence, OB volume was evaluated in patients with PD (n = 16) and healthy control subjects (n = 16). A significant loss of OB volume was observed in patients with PD, compared to the healthy control group (91.2 ± 15.72 versus 131.4 ± 24.56 mm3, respectively). Specifically, decreased height of the left OB appears to be a reliable parameter that is adaptable to clinical practice and significantly correlates with OB volume loss in patients with idiopathic PD. Measuring both the volume and height of the OB by MRI may be a valuable method for the clinical investigation of PD. © 2012 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Object: To investigate the potential of a clinical 3 T scanner to perform MRI of small rodents. Materials and methods: Different dedicated small animal coils and several imaging sequences were evaluated to optimize image quality with respect to SNR, contrast and spatial resolution. As an application, optimal grey-white-matter contrast and resolution were investigated for rats. Furthermore, manganese-enhanced MRI was applied in mice with unilateral crush injury of the optic nerve to investigate coil performance on topographic mapping of the visual projection. Results: Differences in SNR and CNR up to factor 3 and more were observed between the investigated coils. The best grey-white matter contrast was achieved with a high resolution 3D T-weighted TSE (SPACE) sequence. Delineation of the retino-tectal projection and detection of defined visual pathway damage on the level of the optic nerve could be achieved by using a T-weighted, 3D gradient echo sequence with isotropic resolution of (0.2 mm). Conclusions: Experimental studies in small rodents requiring high spatial resolution can be performed by using a clinical 3 T scanner with appropriate dedicated coils. [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Journal of Medicine is the property of Ataturk University, School of Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The purpose of this study was to evaluate the potential of a high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 Tesla for the delineation of the cavernous sinus (CS) anatomy both under normal and under pathological conditions. Methods: Fifteen patients without pathologies in the CS and ten patients with pituitary adenomas were included. The CE-MRA was performed on a 3-Tesla scanner and analyzed collaboratively by two readers. The cranial nerves (CNs) within the CS, namely CNIII, CNIV, CNV1, CNV2, and CNVI, were identified in both patient groups. In the adenoma patients it was also assessed whether and to which extend the adenoma invaded the CS and the spatial relationship between tumor and CNs was determined. Results: In the patients with normal CS anatomy, CNIII could be identified in 100%, CNIV in 86.7%, and CNV1, CNV2, as well as CNVI in 100% of analyzed sides. Pituitary adenomas invaded the CS unilaterally (right side) in four patients, and bilaterally in six patients. In patients with adenomas, the CN could be identified and differentiated from the tumor in the following percentages: CNIII in 100%, CNIV in 70%, both CNV1 and CNV2 in 90%, and CNVI in 100%. In all these cases, the tumor-nerve spatial relationship could be visualized. Conclusions: 3-Tesla CE-MRA allows detailed imaging of the complex anatomy of the CS and its structures. In adenoma patients, it clearly visualizes the spatial relationship between tumor and CNs, and thus might be helpful to optimize presurgical planning. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) constructive interference in steady state (CISS) is a gradient-echo MRI sequence that is used to investigate a wide range of pathologies when routine MRI sequences do not provide the desired anatomic information. The increased sensitivity of the 3D CISS sequence is an outcome of the accentuation of the T2 values between cerebrospinal fluid (CSF) and pathological structures. Apart from its well-recognized applications in the evaluation of the cranial nerves, CSF rhinorrhea and aqueduct stenosis, we have found the CISS sequence to be useful for the cisternal spaces, cavernous sinuses and the ventricular system, where it is useful for detecting subtle CSF-intensity lesions that may be missed on routine spin-echo sequences. This information helps in the management of these conditions. After a brief overview of the physics behind this sequence, we illustrate its clinical applications with representative cases and discuss its potential role in imaging protocols. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: To correlate imaging and audiologic findings in patients with large vestibular aqueduct syndrome (LVAS). Study Design: Retrospective analysis. Methods: Thirty-eight patients with LVAS evident on magnetic resonance imaging with available clinical and audiometric data were selected from the databases of the study institution. Images were analyzed for endolymphatic sac and duct size, evidence of incomplete cochlear partitioning, and endolymphatic sac signal heterogeneity. The endolymphatic duct was measured in two different locations: near the vestibular aperture (EDVA) and at the midpoint between the common crus and the operculum (EDMID). Imaging data were correlated with audiologic variables. Results: There was significant correlation between ears for the audiologic and anatomic variables collected. Twenty-one (62%) patients had a fluctuating or progressive hearing loss, and 13 (38%) remained stable (four were not evaluable). At the time of the analysis, 41% of ears had a profound loss. Significant correlation was identified between the presence of endolymphatic signal heterogeneity and worse pure tone average (PTA). EDVA measures were significantly larger among ears with a progressive pattern of hearing loss when compared to those that were stable. Also, EDVA correlated with PTA and the presence of progressive hearing loss, but EDMID had no such a relationship. Conclusions: Evidence of endolymphatic sac signal heterogeneity and larger measures of endolymphatic width when measured near the vestibule (EDVA) are markers of poorer hearing in these patients. By contrast, midpoint measures of the endolymphatic duct (EDMID) have no correlation with audiometric parameters. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this longitudinal study is to describe the different intralabyrinthine lesions yielding high signal intensity on T1-weighted (T1W) images after intravenous gadolinium and then to analyze the follow-up of these patients.Methods: Thirty-seven patients were included and followed clinically and radiologically. A precise analysis of MR labyrinthine signals allowed exact depiction of the different lesions. Special interest is focused on the intralabyrinthine fluid signal on 3D high-resolution T2W images.Results: The enhanced T1W labyrinthine hyperintensities correspond to two different categories: intralabyrinthine enhancement (15 intralabyrinthine schwannomas, 13 labyrinthitis, 1 inflammatory granuloma) and spontaneous T1W hyperintensities (8 intralabyrinthine hemorrhages). Hemorrhagic lesions show a substantial decrease of the intralabyrinthine fluid signal on the 3D HRT2 that evolves to ossification. In labyrinthitis, the importance of the initial labyrinthine fluid signal decrease on the 3D HRT2 is well correlated with the hearing prognosis.Conclusion: A meticulous analysis of inner ear lesions allows various intralabyrinthine lesions, in particular schwannomas, to be differentiated from labyrinthitis. T1W imaging without gadolinium is essential for the correct diagnosis of rapidly evolving hearing loss. In labyrinthitis and intralabyrinthine hemorrhage, 3D HRT2 brings an interesting prognostic factor for the chance of hearing recovery. [ABSTRACT FROM AUTHOR]

A novel digital pulse-shape analysis (DPSA) was performed for high-resolution position-sensitive gamma-ray spectroscopy with coaxial-type high-purity germanium (HpGe) detectors. The DPSA consisted of two stages that determined the pulse height, the interaction point and the start time by using the chi-square fitting the digitally recorded pulse shapes with calculated shapes. As the DPSA was applied to gamma-ray spectroscopy using HpGe coaxial detectors, we obtained the energy spectra, the time-difference spectra and the interaction depth profiles for the gamma rays emitted from ^133Ba and ^22Na standard sources. The efficiency of the spectroscopic analysis using the DPSA was compared with that using a conventional analog signal process (CASP). Furthermore, we determined the half-lifetime of the first excited state in ^133Cs by using the DPSA. [ABSTRACT FROM PUBLISHER]

Background: Although adhesive arachnoiditis of the spinal cord can cause progressive symptoms associated with syringomyelia or myelomalacia, its surgical resolution based on the imaging diagnosis is not well characterized. This study aims to describe the use of imaging for the diagnosis of focal adhesive arachnoiditis of the spinal cord and its surgical resolution using microsurgical arachnoidolysis. Materials and Methods: Four consecutive patients with symptomatic syringomyelia or myelomalacia caused by focal adhesive arachnoiditis underwent microsurgical arachnoidolysis. Comprehensive imaging evaluation using constructive interference in steady-state (CISS) magnetic resonance imaging (MRI) or myelographic MR imaging using true fast imaging with steady-state precession (TrueFISP) sequences was included before surgery to determine the surgical indication. Results: In all four patients a focal adhesion was identified at the cervical or thoracic level of the spinal cord, a consequence of infection or trauma. Three patients showed modest or minor improvement in neurological function, and one patient was unchanged after surgery. The syringomyelia or myelomalacia resolved after surgery and no recurrence was noted within the follow-up period, which ranged from 5 months to 30 months. Conclusions: MRI diagnosis of focal adhesive arachnoiditis is critical to determine the surgical indication. Microsurgical arachnoidolysis appears to be a straightforward method for stabilizing the progressive symptoms, though the procedure is technically demanding. [ABSTRACT FROM AUTHOR]

Purpose: Improved radiotherapy dose delivery techniques over the past decade have increased the necessity for accurate, independent verification of delivered dose. Compton camera imaging (CCI) systems may have the potential to quantitatively reconstruct three-dimensional dose delivered to the patient with little or no a priori information. Methods: In this work, the adequacy of a Compton camera imaging system for application to radiotherapy dose reconstruction is explored using analytical models of system spatial and dosimetric resolution. The effects of scatter and absorption detector energy resolution, initial photon energy, and detector separation distance on system performance were calculated with the goal of determining whether current detector technology is adequate for such an application. Results: Results indicate that the energy and spatial resolutions associated with current Si and Ge double-sided strip detectors in a planar configuration is sufficient to determine dose deposition to within an average of 1.9 mm and 2.5%. Minimum values of less than 0.5 mm and 1% are achievable under certain conditions. As the energy of the photon incident on the patient increases from 1.0 to 10 MeV, system performance improves at the expense of the range of patient and detector scattering angles over which the system is capable of reconstructing dose deposition to within the acceptable upper limits of 5 mm and 5%. System performance also improves with increasing distance between the scatter and absorption detectors, but is acceptable throughout the range of values likely to be associated with a gantry-mounted system (2–20 cm). Conclusions: The results indicate that Compton camera imaging systems based on current solid-state detector technology have the potential to provide independent verification of dose delivered to a patient during radiation therapy. Further consideration must be given to detector efficiency and image reconstruction algorithms for this application of CCI systems. [ABSTRACT FROM AUTHOR]

Recently available coronal fast magnetic resonance imaging (MRI) has very high spatial resolution with good contrast between the optic nerves and cerebrospinal fluid (CSF). The aim of this study was to evaluate the diagnostic value of coronal fast imaging in optic nerve diseases. Thirty-five patients with various Neuro-ophthalmic conditions including 9 with optic neuritis, 6 with optic atrophy, 5 with glaucoma, 4 with segmental optic nerve hypoplasia and 11 with other optic neuropathies including orbital apex syndrome were evaluated with the three-dimensional fast imaging employing steady-state acquisition (FIESTA) sequence in addition to standard MRI protocols. The optic nerve complexes were evaluated on coronal images of the orbits. Detailed demonstration of the optic nerve complex—the optic nerve, the perineural CSF space and dural sheath—could be readily obtained with FIESTA sequence. The acute phase of both optic neuritis and perineuritis showed enlargement of the perineural CSF space; the optic nerve was swollen in optic neuritis but not in perineuritis. Cases of optic atrophy and glaucoma showed perineural CSF space enlargement with normal optic sheath circumference and a thinner optic nerve, while optic nerve hypoplasia showed a smaller dural sheath circumference without perineural CSF space enlargement. In the cases of orbital apex syndrome optic nerve compression by the extraocular muscles was clearly shown. Coronal FIESTA imaging of the orbit is capable of delineating detailed structural changes in the optic nerve complex and is of diagnostic value for the differentiation of optic nerve diseases. [ABSTRACT FROM AUTHOR]

Hearing loss greater than 30 dB over three contiguous pure-tone frequencies occurring within a three day period is defined as sudden hearing loss. It is usually sensorineural (SS-NHL), unilateral and appears as an otologic emergency. SSNHL has many possibile etiologies such as: labyrinthine viral infection, ischemic or hemorrhagic illness, trauma, immuno-mediated inner ear disease, tumor, inner ear malformation, and an imbalance between perilymphatic and endolymphatic fluid pressure. Nevertheless in almost 80% of cases SSNHL belongs to the idiopathic category because the etiology is unknown. The aim of this study was to test the diagnostic impact of two MR devices. Fifteen cases of SSNHL studied with a 1.5 T unit in our hospital between January 2006 and December 2008 within two weeks of the onset were retrospectively evaluated. Since January 2009 three more patients affected by SSNHL have been scanned with a 3T MR unit. We discuss the diagnostic sensitivity, clinical usefulness and the cost-benefit ratio of the MR systems. [ABSTRACT FROM AUTHOR]

Microvascular compression of the vestibulocochlear nerve is known to cause disabling tinnitus and vertigo. A review of the literature shows that the compression is usually located in the cerebellopontine angle, and that it is usually caused by an artery. The authors add the case of a 46-year-old man with venous compression of the vestibulocochlear nerve inside the internal auditory canal (IAC). The patient presented with a 2-year history of recurrent attacks of disabling vertigo and intermittent high-frequency tinnitus on the right side. Magnetic resonance images showed a small, contrast-enhancing lesion in the fundus of the right IAC, which was suspicious for vestibular schwannoma. During surgical exploration, a large venous loop was found extending into the IAC and compressing the vestibulocochlear nerve. The vessel was mobilized and rerouted out of the IAC. The presumed vestibular schwannoma at the cochlear fossa was left in situ. The patient's symptoms resolved immediately after surgery. Hearing was unchanged postoperatively. On follow-up, there has been no growth of the contrast-enhancing lesion in the IAC for 3 years so far. Disabling vertigo can also be caused by venous microvascular compression of the vestibulocochlear nerve inside the IAC and may be treated successfully by microvascular decompression. A sensitive, conservative approach to lesions in the fundus may be justified in the presence of an additional, more prominent pathology that causes compression of the vestibulocochlear nerve. [ABSTRACT FROM AUTHOR]

Conclusion: Recent advances in clinical MR imagers, such as the 3-Tesla, multi-channel phased-array coil and novel pulse sequences, allow the evaluation of subtle alterations in the inner ear fluid environments and breakdown of the blood-labyrinthine barrier. Intratympanic injection of Gd-DTPA allows the imaging detection of endolymphatic hydrops in patients. Objectives: To describe the current status of inner ear MRI and future directions for imaging. Materials and methods: Based on our experiences and literature research, a brief review of the history and recent developments of inner ear MRI is presented. Results: The 3D-FLAIR technique can detect abnormalities that could not be visualized previously in many inner ear diseases, such as sudden deafness, otosclerosis, lupus erythematosus, mumps, and Ramsay-Hunt syndrome. Imaging techniques, indications, and findings for the visualization of endolymphatic hydrops after intratympanic injection of Gd-DTPA are also discussed. This procedure enabled the visualization of endolymphatic hydrops in vivo. Newly developed 3D-real IR techniques and utilities of 32 channel coil are also presented. [ABSTRACT FROM AUTHOR]

The feasibility of using a Compton camera for multitracer imaging has been demonstrated with the results of two biological sample imaging experiments. The distribution of the multitracer administered to a soybean sample and a tumor-bearing mouse has been visualized for each nuclide simultaneously. 3D images of the multitracer have been obtained even though the samples were measured from a fixed direction. [ABSTRACT FROM AUTHOR]

Abstract Introduction  The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. Methods  In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. Results  The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. Conclusion  There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells. [ABSTRACT FROM AUTHOR]

Purpose To examine the ability of TrueFISP imaging for evaluating tumor size in mouse brain at high field. Materials and Methods Brains of healthy and glioma-implanted nude mice were imaged at 4.7T and 9.4T. 3D imaging was performed with TrueFISP and T2w-RARE. Radiofrequency pulses with alternating phase and the sum-of-squares reconstruction method were used in TrueFISP imaging. The contrast-to-noise ratio (CNR) was evaluated in healthy and in tumoral brain regions. Results Banding artifact was correctly suppressed in TrueFISP images thanks to the method used. The signal-to-noise ratio (SNR) and CNR were comparable in TrueFISP and T2w-RARE images at 4.7T, but acquisition was around 4 times shorter with TrueFISP. Tumor was well detected at 4.7T with TrueFISP, but CNR between tumor and healthy tissue was low at 9.4T. Conclusion TrueFISP is efficient and fast to perform brain imaging at 4.7T. Multiple TrueFISP acquisitions with phase-cycled radiofrequency (RF) pulses and sum-of-squares reconstruction allow suppression of banding artifact. Tumoral regions were well detected and the method allows longitudinal studies of tumor growth. J. Magn. Reson. Imaging 2008;28:497-503. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate whether the parenchymal lung damage in patients suffering from cystic fibrosis (CF) can be equivalently quantified by the Chrispin-Norman (CN) scores determined with low-field magnetic resonance imaging (MRI) and conventional chest radiography (CXR). Both scores were correlated with pulmonary function tests (PFT) and the Shwachman-Kulczycki method (SKM). To evaluate the comparability of MRI and CXR for different states of the disease, all scores were applied to patients divided into three age groups. Seventy-three CF patients (mean SKM score: 62 +/- 8) with a median age (range) of 14 years (7-32) were included. The mean CN scores determined with both imaging methods were comparable (CXR: 12.1 +/- 4.7; MRI: 12.0 +/- 4.5) and showed high correlation (P < 0.05, R = 0.97). Only weak correlations were found between imaging, PFT, and SKM. Both imaging modalities revealed significantly more severe disease expression with age, while PFT and SKM failed to detect early signs of disease. We conclude that imaging of the lung in CF patients is capable of detecting subtle and early parenchymal destruction before lung function or clinical scoring is affected. Furthermore, low-field MRI revealed high consistency with chest radiography and may be used for a thorough follow-up while avoiding radiation exposure. [ABSTRACT FROM AUTHOR]

The purpose of this work was to implement autocalibrating GRAPPA-based parallel imaging (PI) for in vivo high-resolution (HR) MRI of cartilage and trabecular bone micro-architecture at 7T and to evaluate its performance based on comparison of MR-derived morphology metrics between accelerated and conventional images and comparison of geometry factor measures between 3T and 7T. Using an eight channel coil array for trabecular MRI at the ankle, a higher maximum feasible acceleration (R) = 6 and lower geometry factor values than that at 3T were observed. The advantages of two-dimensional acceleration were also demonstrated. In knee cartilage and bone acquisitions, feasibility of PI with a dual-channel quadrature coil was investigated. Robust quantification of bone and cartilage metrics could be derived from accelerated ankle and knee acquisitions. PI can enhance the clinical feasibility of in vivo bone and cartilage HR-MRI for osteoporosis and osteoarthritis at 7T. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Imaging of the temporal bone is under continous developement. In the recent decades the technical advances of magnetic resonance imaging and computed tomography have contributed to improved imaging quality in assessment of the temporal bone. Dedicated imaging protocols have been developed and are routinely employed in most institutions. However, imaging interpretation remains challenging, since the temporal bone is an anatomically highly complex region and most diseases of the inner ear occur with low incidence, so that even radiologists experienced in the field may be confronted with such entities for the first time. The current review gives an overview about symptoms and imaging appearance of malformations and acquired lesion of the inner ear. [ABSTRACT FROM AUTHOR]

The timing performance of a Compton PET device for very high resolution small animal imaging was investigated using Monte Carlo simulation data and timing simulations. The PET instrument was designed with an inner cylindrical silicon detector for scattering, surrounded by an outer cylindrical BGO scintillation detector for absorption. The time intervals between adjacent decay events of the annihilation photon source were extracted in accordance with the Poisson distribution for various source activities. Interaction time was estimated by adding the time of flight (TOF) obtained from Monte Carlo simulation data and timing uncertainty of the silicon and BGO detector to the decay time intervals. A Gaussian distribution (5 ns FWHM) and mono-exponential model (1.0 photoelectron/ns) were used for timing uncertainties of the silicon and BGO detectors, respectively. Maximizing the noise equivalent count rate (NECR) resulted in an energy window of ±50% of total energy sum and a timing window of 7 ns. Additional constraints imposed by the use of Compton kinematics information in this device proved valuable in rejecting random coincidences, object scatter and misclassified events. The improvement is most pronounced at high source activity. [ABSTRACT FROM AUTHOR]

With a high likelihood of clinical improvement and low rates of complications, minimally invasive neuroendoscopic surgery is becoming the treatment of choice for symptomatic or growing arachnoid cysts. In neuroendoscopic surgery, visualization of anatomical landmarks is essential in achieving successful fenestration without complications. Because of the restricted visual field in neuroendoscopic surgery, preoperative anatomical assessment is very helpful. Magnetic resonance cisternography (MRC) with high spatial resolution and contrast, using for example 3-D Fourier transformation constructive interference in steady state (CISS) or fast imaging employing steady-state acquisition (FIESTA) sequences, is able to detect the arachnoid cyst wall and neighboring anatomical structures as the anatomical landmarks. We retrospectively reviewed T2-weighted (T2-W) fast spin-echo images, and the MRC and intraoperative findings. Axial and coronal T2-W images (6 and 3 mm thickness, respectively) and axial and coronal 0.8 mm thick MRC images with CISS or FIESTA were obtained from four patients with arachnoid cysts treated by neuroendoscopic surgery. Intraoperative findings were reviewed on videotape recorded during the procedures. At the brain surface, the arachnoid cyst wall could be detected clearly in any of the four patients on MRC images, and was only partly seen in the fourth patient T2-W images. Adjacent important anatomical structures including vessels and cranial nerves, and an enough space for cystocisternostomy were identified on MRC images, and the findings were consistent with the findings during neuroendoscopic surgery. Preoperative identification of the arachnoid cyst wall and surrounding anatomical structures by MRC may help avoid complications and allow safer neuroendoscopic surgery. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate three-dimensional Fourier transformation-constructive interference in steady-state (CISS) imaging as a preoperative anatomical evaluation of the relationship between the placode, spinal nerve roots, CSF space, and the myelomeningocele sac in neonates with lumbosacral myeloschisis. Five consecutive patients with lumbosacral myeloschisis were included in this study. Magnetic resonance (MR) CISS, conventional T1-weighted (T1-W) and T2-weighted (T2-W) images were acquired on the day of birth to compare the anatomical findings with each sequence. We also performed curvilinear reconstruction of the CISS images, which can be reconstructed along the curved spinal cord and neural placode. Neural placodes were demonstrated in two patients on T1-W images and in three patients on T2-W images. T2-W images revealed a small number of nerve roots in two patients, while no nerve roots were demonstrated on T1-W images. In contrast, CISS images clearly demonstrated neural placodes and spinal nerve roots in four patients. These findings were in accordance with intraoperative findings. Curvilinear CISS images demonstrated the neuroanatomy around the myeloschisis in one slice. The resulting images were degraded by a band artifact that obstructed fine anatomical analysis of the nerve roots in the ventral CSF space. The placode and nerve roots could not be visualized in one patient in whom the CSF space was narrow due to the collapse of the myelomeningocele sac. MR CISS imaging is superior to T1-W and T2-W imaging for demonstrating the neural placode and nerve roots, although problems remain in terms of artifacts. [ABSTRACT FROM AUTHOR]

The feasibility of using a Compton camera for multitracer imaging has been demonstrated with the results of two biological sample imaging experiments. The distribution of the multitracer administered to a soybean sample and a tumor-bearing mouse has been visualized for each nuclide simultaneously. Three-dimensional images of the multitracer have been obtained even though the samples were measured from a fixed direction. [ABSTRACT FROM AUTHOR]

AbstractBackground: The diagnosis of benign paroxysmal positional vertigo (BPPV) is easy when typical nystagmus is present. However, diagnostic doubts arise when faced with cases presenting atypical features of the positional paroxysmal nystagmus as well as the clinical course and disease evolution. Methods: A morphological evaluation of inner ear structures via high-resolution magnetic resonance (HR-MR) studies has been performed in 2 patients that did not respond to traditional therapeutic manoeuvres. Results: In 1 patient, a filling defect at the level of the middle portion of the right lateral semicircular canal (LSC) has been demonstrated, while in the second one, a geometric-architectural abnormality – a ‘fold’ in the LSC – has been observed. Conclusion: HR-MR study of the inner ear offers a meaningful contribution to interpreting the physiopathogenesis of atypical cases of BPPV. HR-MR of the inner ear is a safe and useful tool to investigate patients with atypical and intractable BPPV.Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In this work the generalized autocalibrating partially parallel acquisition (GRAPPA) technique was implemented with modified reconstruction and applied to in vivo high-resolution (HR) magnetic resonance imaging (MRI) of the trabecular bone microarchitecture at 3 Tesla (T) with a multiple-acquisition balanced steady-state free precession (b-SSFP) sequence. Trabecular bone is made up of a network of microstructures (80-140 μm), and its structural deterioration is associated with the skeletal metabolic disorder osteoporosis. HR-MRI is a promising noninvasive tool for assessing the trabecular microarchitecture in vivo, but it involves long acquisition times. Using partially parallel imaging (PPI) to accelerate the acquisition may help mitigate this shortcoming and allow more flexibility in protocol design. In this study the effects of GRAPPA-based reconstruction on image characteristics and the measurement of trabecular bone structural parameters were evaluated. Initial studies showed that image quality and depiction of microstructure were preserved in the GRAPPA-based reconstruction, indicating the feasibility of PPI in HR-MRI of trabecular bone. The results also demonstrated the potential of PPI for increasing the signal-to-noise ratio (SNR) efficiency of multiple-acquisition b-SSFP imaging protocols. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Clinical MRI at a field strength of 3.0T is finding increasing use. However, along with the advantages of 3.0T, such as increased SNR, there can be drawbacks, including increased levels of imaging artifacts. Although every imaging artifact observed at 3.0T can also be present at 1.5T, the intensity level is often higher at 3.0T and thus the artifact is more objectionable. This review describes some of the imaging artifacts that are commonly observed with 3.0T imaging, and their root causes. When possible, countermeasures that reduce the artifact level are described. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clinical Neuroradiology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to compare the ability of T2-weighted three-dimensional turbo spin-echo (TSE) images, maximum intensity projections and three-dimensional volume-rendered images for delineation of semicircular canal dehiscence. In 26 patients with dehiscence of the superior and/or posterior semicircular canal and 26 control patients, TSE images were obtained with two different resolutions and maximum intensity projection (MIP) and 3D volume-rendered images reconstructed. All images were evaluated by two radiologists in consensus regarding the visualization of anatomical structures and dehiscence of the semicircular canals. Computed tomography was used to confirm or exclude dehiscence. Dehiscence of the semicircular canals was delineated on axial MR images and on 3D volume-rendered images, but not on MIP images. The number of false positive cases was reduced from 3 to 0 with an increase in matrix, rendering results similar to those obtained with CT. Dehiscence of the semicircular canals can be assessed on high resolution MR images. Volume-rendered 3D images allow for immediate perception of the location of defects in semicircular canal dehiscence. These images may facilitate understanding of the extent and location of the defects. [ABSTRACT FROM AUTHOR]

Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to the canalolithiasis theory, benign paroxysmal vertigo (BPPV) is caused by gravity-dependent movements of otoconial debris that collects in the endolymph of the posterior semicircular canal. Other parts of the vestibular organ are rarely affected, and it is mainly the horizontal canal that is affected by this atypical form of BPPV. Canalolithiasis of the superior semicircular canal must be considered an anomaly because the superior semicircular canal is the highest point of the vestibular organ and debris normally cannot collect in this special location. Until now, BPPV of the superior canal has mainly been dealt with theoretically in the literature. The authors present three patients with canalolithiasis of the superior semicircular canal and offer direct proof of the condition using high-resolution 3D MRI. [ABSTRACT FROM AUTHOR]

Correct diagnosis of intracanalicular neoplasms is important to avoid unnecessary operations or an unsuitable surgical approach. We investigated the capability of high-resolution three-dimensional MR imaging in predicting the origin of intracanalicular neoplasms. Twenty cases underwent three-dimensional Fourier-transformation (3DFT) constructive interference in steady state and contrast-enhanced 3DFT-fast low angled shot MR imaging and surgery. Seventeen cases underwent caloric test. MR diagnosis on the origin of intracanalicular neoplasms was compared with surgical results. For MR diagnosis, the origin of intracanalicular neoplasms was predicted according to the location of the tumor in the internal auditory canal (IAC) in two ways, i.e., determining (1) a single specific nerve of origin and (2) whether the tumor originated from the superior or inferior aspect of the IAC. Surgery could determine the nerve of origin in 16 cases (14 inferior and 2 superior vestibular schwannomas), but it was indeterminate in 4. Comparison between MR prediction and surgical results on a single nerve origin revealed exact agreement in five, but inconsistent in three. Regarding whether the tumor was derived from superior or inferior aspect of the IAC, agreement was found in 10 of the 16 cases (62.5%). Caloric test was abnormal in all patients examined but one with superior vestibular schwannoma. 3DFT-MR imaging was not particularly useful in predicting a precise nerve of origin of intracanalicular neoplasms. The prediction on whether the tumor originated in the superior or inferior aspect of the IAC was superior to caloric test, which might have clinical significance in treatment planning especially for hearing preservation surgery. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the potential of fully-balanced steady-state free-precession (SSFP) sequences in in vivo high-resolution (HR) MRI of trabecular bone at field strengths of 1.5 and 3 T by simulation and experimental methods. Materials and Methods Using simulation studies, refocused SSFP acquisition was optimized for our imaging purposes with a focus on signal-to-noise ratio (SNR) and SNR efficiency. The signal behavior in trabecular bone was estimated using a magnetostatic model of the trabecular bone and marrow. Eight normal volunteers were imaged at the proximal femur, calcaneus, and the distal tibia on a GE Signa scanner at 1.5 and at 3 T with an optimized single-acquisition SSFP sequence (three-dimensional FIESTA) and an optimized multiple-acquisition SSFP sequence (three-dimensional FIESTA-c). Images were also acquired with a fast gradient echo (FGRE) sequence for evaluation of the SNR performance of SSFP methods. Results Refocused SSFP images outperformed FGRE acquisitions in both SNR and SNR efficiency at both field strengths. At 3 T, susceptibility effects were visible in FIESTA and FGRE images and much reduced in FIESTA-c images. The magnitude of SNR boost at 3 T was closely predicted by simulations. Conclusion Single-acquisition SSFP (at 1.5 T) and multiple-acquisition SSFP (at 3 T) hold great potential for HR-MRI of trabecular bone. J. Magn. Reson. Imaging 2005;21:818-825. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]