50 resultados para Gadolinium Anomaly
Resumo:
Double fenestration of the anterior communicating artery (ACoA) complex associated with an aneurysm is a very rare finding and is usually caused by ACoA duplication and the presence of a median artery of the corpus callosum (MACC). We present a patient in whom double fenestration was not associated with ACoA duplication or even with MACC, representing therefore, a previously unreported anatomic variation. A 43 year old woman experienced sudden headache and the CT scans showed subarachnoid haemorrhage (SAH). On admission, her clinical condition was consistent with Hunt and Hess grade II. Conventional digital subtraction angiography (DSA) was performed and revealed multiple intracranial aneurysms arising from both middle cerebral arteries (MCA) and from the ACoA. Three-dimensional rotational angiography (3D-RA) disclosed a double fenestration of the ACoA complex which was missed by DSA. The patient underwent a classic pterional approach in order to achieve occlusion of both left MCA and ACoA aneurysms by surgical clipping. The post-operative period was uneventful. A rare anatomical variation characterised by a double fenestration not associated with ACoA duplication or MACC is described. The DSA images missed the double fenestration which was disclosed by 3D-RA, indicating the importance of 3D-RA in the diagnosis and surgical planning of intracranial aneurysms.
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PURPOSE: To prospectively quantify in vitro the influence of gadopentetate dimeglumine and ioversol on the magnetic resonance (MR) imaging signal observed with a variety of musculoskeletal pulse sequences to predict optimum gadolinium concentrations for direct MR arthrography at 1.5 and 3.0 T. MATERIALS AND METHODS: In an in vitro study, T1 and T2 relaxation times of three dilution series of gadopentetate dimeglumine (concentration, 0-20.0 mmol gadolinium per liter) at ioversol concentrations with iodine concentration of 0, 236.4, and 1182 mmol iodine per liter (corresponding to 0, 30, and 150 mg of iodine per milliliter) were measured at 1.5 and 3.0 T. The relaxation rate dependence on concentrations of gadolinium and iodine was analytically modeled, and continuous profiles of signal versus gadolinium concentration were calculated for 10 pulse sequences used in current musculoskeletal imaging. After fitting to experimental discrete profiles, maximum signal-to-noise ratio (SNR), gadolinium concentration with maximum SNR, and range of gadolinium concentration with 90% of maximum SNR were derived. The overall influence of field strength and iodine concentration on these parameters was assessed by using t tests. The deviation of simulated from experimental signal-response profiles was assessed with the autocorrelation of the residuals. RESULTS: The model reproduced relaxation rates of 0.37-38.24 sec(-1), with a mean error of 4.5%. Calculated SNR profiles matched the discrete experimental profiles, with autocorrelation of the residuals divided by the mean of less than 5.0. Admixture of ioversol consistently reduced T1 and T2, narrowed optimum gadolinium concentration ranges (P = .004-.006), and reduced maximum SNR (P < .001 to not significant). Optimum gadolinium concentration was 0.7-3.4 mmol/L at both field strengths. At 3.0 T, maximum SNR was up to 75% higher than at 1.5 T. CONCLUSION: Admixture of ioversol to gadopentetate dimeglumine solutions results in a consistent additional relaxation enhancement, which can be analytically modeled to allow a near-quantitative a priori optimized match of contrast media concentrations and imaging protocol for a broad variety of pulse sequences.
Resumo:
OBJECTIVES: To study the three-dimensional (3D) T1 patterns in different types of femoroacetabular impingement (FAI) by utilizing delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and subsequent 3D T1 mapping. We used standard grading of OA by Tonnis grade on standard radiographs and morphological grading of cartilage in MRI for comparative analysis. METHODS: dGEMRIC was obtained from ten asymptomatic young-adult volunteers and 26 symptomatic FAI patients. MRI included the routine hip protocol and a dual-flip angle (FA) 3D gradient echo (GRE) sequence utilizing inline T1 measurement. Cartilage was morphologically classified from the radial images based on the extent of degeneration as: no degeneration, degeneration zone measuring <0.75 cm from the rim, >0.75 cm, or total loss. T1 findings were evaluated and correlated. RESULTS: All FAI types revealed remarkably lower T1 mean values in comparison to asymptomatic volunteers in all regions of interest. Distribution of the T1 dGEMRIC values was in accordance with the specific FAI damage pattern. In cam-types (n=6) there was a significant drop (P<0.05) of T1 in the anterior to superior location. In pincer-types (n=7), there was a generalized circumferential decrease noted. High inter-observer (intra-observer) reliability was noted for T1 assessment using intra-class correlation (ICC):intra-class coefficient=0.89 (0.95). CONCLUSIONS: We conclude that a pattern of zonal T1 variation does seem to exist that is unique for different sub-groups of FAI. The FA GRE approach to perform 3D T1 mapping has a promising role for further studies of standard MRI and dGEMRIC in the hip joint.
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The purpose of this study was to assess if delayed gadolinium MRI of cartilage using postcontrast T(1) (T(1Gd)) is sufficient for evaluating cartilage damage in femoroacetabular impingement without using noncontrast values (T(10)). T(1Gd) and DeltaR(1) (1/T(1Gd) - 1/T(10)) that include noncontrast T(1) measurements were studied in two grades of osteoarthritis and in a control group of asymptomatic young-adult volunteers. Differences between T(1Gd) and DeltaR(1) values for femoroacetabular impingement patients and volunteers were compared. There was a very high correlation between T(1Gd) and DeltaR(1) in all study groups. In the study cohort with Tonnis grade 0, correlation (r) was -0.95 and -0.89 with Tonnis grade 1 and -0.88 in asymptomatic volunteers, being statistically significant (P < 0.001) for all groups. For both T(1Gd) and DeltaR(1), a statistically significant difference was noted between patients and control group. Significant difference was also noted for both T(1Gd) and DeltaR(1) between the patients with Tonnis grade 0 osteoarthritis and those with grade 1 changes. Our results prove a linear correlation between T(1Gd) and DeltaR(1), suggesting that T(1Gd) assessment is sufficient for the clinical utility of delayed gadolinium MRI of cartilage in this setting and additional time-consuming T(10) evaluation may not be needed.
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Factors such as instability and impingement lead to early cartilage damage and osteoarthritis of the hip joint. The surgical outcome of joint-preserving surgery about the hip joint depends on the preoperative quality of joint cartilage.For in vivo evaluation of cartilage quality, different biochemically sensitive magnetic resonance imaging (MRI) procedures have been tested, some of which have the potential of inducing a paradigm shift in the evaluation and treatment of cartilage damage and early osteoarthritis.Instead of reacting to late sequelae in a palliative way, physicians could assess cartilage damage early on, and the treatment intensity could be adequate and based on the disease stage. Furthermore, the efficiency of different therapeutic interventions could be evaluated and monitored.This article reviews the recent application of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and discusses its use for assessing cartilage quality in the hip joint. dGEMRIC is more sensitive to early cartilage changes in osteoarthritis than are radiographic measures and might be a helpful tool for assessing cartilage quality.
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PURPOSE: To determine the feasibility of assessing early osteoarthritis (OA) in hips with femoroacetabular impingement (FAI) using delayed Gadolinium enhanced MRI of Cartilage (dGEMRIC). MATERIALS AND METHODS: Thirty-seven hips in 30 patients who had a dGEMRIC scan and radiographic evidence of FAI were identified. Clinical symptoms were assessed. Radiographic measurements were performed to determine acetabular and femoral morphology. The severity of radiographic OA was determined using Tönnis grade and minimum joint space width (JSW). On MRI, the alpha angle was measured on the sagittal oblique slices. Correlations between dGEMRIC index, patient symptoms, morphologic measurements, radiographic OA, and age were determined. RESULTS: Significant correlations were observed between dGEMRIC index, pain (P < 0.05), and alpha angle (P < 0.05). The correlation of dGEMRIC with alpha angle suggests that hips with more femoral deformity show signs of early OA. CONCLUSION: The results of osteoplasty for FAI depend on the amount of pre-existing OA in the joint. dGEMRIC may be a useful technique for diagnosis and staging of early osteoarthritis in hips with impingement.
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The patent nasopalatine duct is a rare anomaly in the anterior maxilla. During the early fetal period, a bilateral and epithelium-lined duct is formed within the primary palatal process as an oro-nasal communication. However, the duct obliterates and degenerates before birth. A persisting patent or through-and-through nasoplatine duct is therefore considered a developmental anomaly. A patent nasopalatine duct normally presents as one (or two) tiny openings lateral or posterior to the incisive papilla. In such a case, the ducts can be partially or completely probed with gutta-percha points with subsequent radiographic imaging. The patients report strange sensations such as squeaking noise, palatal drainage, nasal regurgitation, or airway communication between nasal and oral cavities; however, patients rarely complain about pain. About 40 cases have been documented in the literature. We describe two patients who have been referred to our department for evaluation of "sinus tracts" in the anterior palate. Since a patent nasopalatine duct can become a diagnostic pitfall, a thorough inspection of the mucosa around the incisive papilla is essential to avoid unnecessary endodontic or surgical interventions in the area of the central maxillary incisors.
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UNLABELLED The abnormal development of the tricuspid valve in patients with Ebstein's anomaly results in several activation abnormalities including delayed intraatrial conduction, right bundle branch block (RBBB), and ventricular preexcitation. The aim of the present study was to define the ECG characteristics before and after ablation of an accessory A-V pathway (AP) in patients with Ebstein's anomaly. METHODS A series of 226 consecutive patients with Ebstein's anomaly was studied. Sixty-four patients (28%) had documented tachycardia. Thirty-three patients with recurrent tachycardia were found to have a single right-sided AP that was successfully ablated (study group). Thirty patients without tachycardia served as the control group. RESULTS Only 21 of 33 patients (62%) had a typical ECG pattern of preexcitation. In addition, none of the patients had an ECG pattern of RBBB during sinus rhythm. In contrast, 28 of 30 (93%) patients in the control group had RBBB (P < 0.001). Radiofrequency catheter ablation resulted in appearance of RBBB in 31 of 33 (94%) patients. The absence of RBBB in patients with Ebstein's anomaly and recurrent tachycardia had a 98% sensitivity and 92% specificity for the diagnosis of an AP. The positive predictive value was 91% (0.77, 0.97 CI 95%) and the negative predictive value was 98% (0.85, 0.99 CI 95%). CONCLUSION One-third of patients with Ebstein's anomaly and symptomatic tachyarrhythmias have minimal or absent ECG features of ventricular preexcitation. In these patients, the absence of RBBB pattern is a strong predictor of an AP.
Electroweak gauge-boson and Higgs production at Small qT: Infrared safety from the collinear anomaly
Resumo:
We discuss the differential cross sections for electroweak gauge-boson and Higgs production at small and very small transverse momentum q_T. Large logarithms are resummed using soft-collinear effective theory. The collinear anomaly generates a non-perturbative scale q^∗, which protects the processes from receiving large long-distance hadronic contributions. A numerical comparison of our predictions with data on the transverse-momentum distribution in Z-boson production at the Tevatron and LHC is given.
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The formation of electric potential over lunar magnetized regions is essential for understanding fundamental lunar science, for understanding the lunar environment, and for planning human exploration on the Moon. A large positive electric potential was predicted and detected from single point measurements. Here, we demonstrate a remote imaging technique of electric potential mapping at the lunar surface, making use of a new concept involving hydrogen neutral atoms derived from solar wind. We apply the technique to a lunar magnetized region using an existing dataset of the neutral atom energy spectrometer SARA/CENA on Chandrayaan-1. Electrostatic potential larger than +135 V inside the Gerasimovic anomaly is confirmed. This structure is found spreading all over the magnetized region. The widely spread electric potential can influence the local plasma and dust environment near the magnetic anomaly.
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A search for direct chargino production in anomaly-mediated supersymmetry breaking scenarios is performed in p p collisions at root s = 7 TeV using 4.7 fb(-1) of data collected with the ATLAS experiment at the LHC. In these models, the lightest chargino is predicted to have a lifetime long enough to be detected in the tracking detectors of collider experiments. This analysis explores such models by searching for chargino decays that result in tracks with few associated hits in the outer region of the tracking system. The transverse-momentum spectrum of candidate tracks is found to be consistent with the expectation from the Standard Model background processes and constraints on chargino properties are obtained.
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We show that nonperturbative effects are logarithmically enhanced for transverse-momentum-dependent observables such as qT spectra of electroweak bosons in hadronic collisions and jet broadening at e+e− colliders. This enhancement arises from the collinear anomaly, a mechanism characteristic for transverse observables, which induces logarithmic dependence on the hard scale in the product of the soft and collinear matrix elements. Our analysis is based on an operator product expansion and provides, for the first time, a systematic, model-independent way to study nonperturbative effects for this class of observables. For the case of jet broadening, we relate the leading correction to the nonperturbative shift of the thrust distribution.
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The Toledoth Yeshu, the “Generation,” or “Life of Jesus,” have been described as an anti-Gospel, or a parody of the Gospel. This protean tradition, witnessed in more than hundred manuscripts and printed editions, offers a “counter-history” of the life of Jesus and the origins of Christianity. According to this mischievous narrative Jesus was an illegitimate child turned charlatan, and his disciples a bunch of violent and senseless rogues who continued to stir up trouble in Israel even following their leader’s shameful hanging. The Toledoth Yeshu is the story of an anomaly (Jesus and the birth of Christianity). It is also a story about confusion: marital confusion, social confusion, and religious confusion. As an exercise in “historical imagination,” the Toledoth Yeshu offers a narrative of religions compared, and a reflection on social and religious borders, on their instability and fragility, and ultimately on their necessity. The present paper will explore the normative dimension of the Toledoth Yeshu tradition: the way the “disorder of things” the narrative relates also conveys a powerful discourse on social and religious norms. We will also seek to map this tradition in the broader context of medieval Jewish discussions on Jesus (particularly Maimonides) as a “case” in the religious history of mankind, addressing issues of false prophecy, religious deviation, transgression, and heresy.