Imaging spectrum of the operated bladder : P41

Multiple complex procedures involving the bladder have been developed by surgeons in both children and adults, with their own advantages and drawbacks. A greater knowledge of the anatomic changes induced by each category of procedure is mandatory in the follow-up of patients and detection of early and late postoperative complications. A retrospective review of 50 pediatric and adult patients referred or treated in our institution is presented. The combined use of plain films, IVP, MCUG, US, Doppler US, CT, 3DCT and MRI is described. The imaging features are compared with surgical and anatomopathological findings. The purpose of this pictorial essay is to present a wide spectrum of diagnostic imaging findings in children and adult patients with operated bladder. The imaging features of surgical procedures with preserved, partially replaced and totally replaced bladder are described, with emphasis on a systematic multimodality approach. Learning objectives: 1) To provide an in-depth review of bladder surgical procedures with their indications, anatomopathological and imaging features. 2) To describe optimal multimodality imaging techniques for evaluating the operated bladder.

Imagerie et arthrose [Imaging in osteoarthritis].

Plain radiography remains useful for the diagnosis of osteoarthritis, even if it is not always essential. It is moreover poorly correlated with symptoms, as it reflects rather the accumulation of damage then active processes. Similarly, it is a poor indicator of the progression of osteoarthritis. Modem imaging, particularly MRI, has allowed us to understand better the evolving processes, demonstrating a good correlation with symptoms and a better predictive value of clinical course. It has gradually replaced standard radiography in the study because it directly demonstrates sequelae and the active processes in all the structures of the joint. It remains clinically indicated only to exclude an alternative diagnosis or to determine a possible complication of osteoarthritis.

Relationship between motion of coronary arteries and diaphragm during free breathing: lessons from real-time MR imaging.

OBJECTIVE: Diaphragmatic navigators are frequently used in free-breathing coronary MR angiography, either to gate or prospectively correct slice position or both. For such approaches, a constant relationship between coronary and diaphragmatic displacement throughout the respiratory cycle is assumed. The purpose of this study was to evaluate the relationship between diaphragmatic and coronary artery motion during free breathing. SUBJECTS AND METHODS: A real-time echoplanar MR imaging sequence was used in 12 healthy volunteers to obtain 30 successive images each (one per cardiac cycle) that included the left main coronary artery and the domes of both hemidiaphragms. The coronary artery and diaphragm positions (relative to isocenter) were determined and analyzed for effective diaphragmatic gating windows of 3, 5, and 7 mm (diaphragmatic excursions of 0-3, 0-5, and 0-7 mm from the end-expiratory position, respectively). RESULTS: Although the mean slope correlating the displacement of the right diaphragm and the left main coronary artery was approximately 0.6 for all diaphragmatic gating windows, we also found great variability among individual volunteers. Linear regression slopes varied from 0.17 to 0.93, and r2 values varied from .04 to .87. CONCLUSION: Wide individual variability exists in the relationship between coronary and diaphragmatic respiratory motion during free breathing. Accordingly, coronary MR angiographic approaches that use diaphragmatic navigator position for prospective slice correction may benefit from patient-specific correction factors. Alternatively, coronary MR angiography may benefit from a more direct assessment of the respiratory displacement of the heart and coronary arteries, using left ventricular navigators.

Quantitative analysis of crystal/grain sizes and their distributions in 2D and 3D

We review methods to estimate the average crystal (grain) size and the crystal (grain) size distribution in solid rocks. Average grain sizes often provide the base for stress estimates or rheological calculations requiring the quantification of grain sizes in a rock's microstructure. The primary data for grain size data are either 1D (i.e. line intercept methods), 2D (area analysis) or 3D (e.g., computed tomography, serial sectioning). These data have been used for different data treatments over the years, whereas several studies assume a certain probability function (e.g., logarithm, square root) to calculate statistical parameters as the mean, median, mode or the skewness of a crystal size distribution. The finally calculated average grain sizes have to be compatible between the different grain size estimation approaches in order to be properly applied, for example, in paleo-piezometers or grain size sensitive flow laws. Such compatibility is tested for different data treatments using one- and two-dimensional measurements. We propose an empirical conversion matrix for different datasets. These conversion factors provide the option to make different datasets compatible with each other, although the primary calculations were obtained in different ways. In order to present an average grain size, we propose to use the area-weighted and volume-weighted mean in the case of unimodal grain size distributions, respectively, for 2D and 3D measurements. The shape of the crystal size distribution is important for studies of nucleation and growth of minerals. The shape of the crystal size distribution of garnet populations is compared between different 2D and 3D measurements, which are serial sectioning and computed tomography. The comparison of different direct measured 3D data; stereological data and direct presented 20 data show the problems of the quality of the smallest grain sizes and the overestimation of small grain sizes in stereological tools, depending on the type of CSD. (C) 2011 Published by Elsevier Ltd.

In vivo imaging of T cell delivery to tumors after adoptive transfer therapy.

Adoptive transfer therapy of in vitro-expanded tumor-specific cytolytic T lymphocytes (CTLs) can mediate objective cancer regression in patients. Yet, technical limitations hamper precise monitoring of posttherapy T cell responses. Here we show in a mouse model that fused single photon emission computed tomography and x-ray computed tomography allows quantitative whole-body imaging of (111)In-oxine-labeled CTLs at tumor sites. Assessment of CTL localization is rapid, noninvasive, three-dimensional, and can be repeated for longitudinal analyses. We compared the effects of lymphodepletion before adoptive transfer on CTL recruitment and report that combined treatment increased intratumoral delivery of CTLs and improved antitumor efficacy. Because (111)In-oxine is a Food and Drug Administration-approved clinical agent, and human SPECT-CT systems are available, this approach should be clinically translatable, insofar as it may assess the efficacy of immunization procedures in individual patients and lead to development of more effective therapies.

European Association of Veterinary Diagnostic Imaging : 4th European conferece : matkakertomus

Mirja Ruohoniemi

Steady-state equilibrium phase inversion recovery ON-resonant water suppression (IRON) MR angiography in conjunction with superparamagnetic nanoparticles. A robust technique for imaging within a wide range of contrast agent dosages.

PURPOSE: To investigate the ability of inversion recovery ON-resonant water suppression (IRON) in conjunction with P904 (superparamagnetic nanoparticles which consisting of a maghemite core coated with a low-molecular-weight amino-alcohol derivative of glucose) to perform steady-state equilibrium phase MR angiography (MRA) over a wide dose range. MATERIALS AND METHODS: Experiments were approved by the institutional animal care committee. Rabbits (n = 12) were imaged at baseline and serially after the administration of 10 incremental dosages of 0.57-5.7 mgFe/Kg P904. Conventional T1-weighted and IRON MRA were obtained on a clinical 1.5 Tesla (T) scanner to image the thoracic and abdominal aorta, and peripheral vessels. Contrast-to-noise ratios (CNR) and vessel sharpness were quantified. RESULTS: Using IRON MRA, CNR and vessel sharpness progressively increased with incremental dosages of the contrast agent P904, exhibiting constantly higher contrast values than T1 -weighted MRA over a very wide range of contrast agent doses (CNR of 18.8 ± 5.6 for IRON versus 11.1 ± 2.8 for T1 -weighted MRA at 1.71 mgFe/kg, P = 0.02 and 19.8 ± 5.9 for IRON versus -0.8 ± 1.4 for T1-weighted MRA at 3.99 mgFe/kg, P = 0.0002). Similar results were obtained for vessel sharpness in peripheral vessels, (Vessel sharpness of 46.76 ± 6.48% for IRON versus 33.20 ± 3.53% for T1-weighted MRA at 1.71 mgFe/Kg, P = 0.002, and of 48.66 ± 5.50% for IRON versus 19.00 ± 7.41% for T1-weighted MRA at 3.99 mgFe/Kg, P = 0.003). CONCLUSION: Our study suggests that quantitative CNR and vessel sharpness after the injection of P904 are consistently higher for IRON MRA when compared with conventional T1-weighted MRA. These findings apply for a wide range of contrast agent dosages.

Imagerie cardiaque non invasive: apport spécifique en clinique des nouvelles modalités (II). Evaluation fonctionnelle [Cardiac imaging: specific clinical role of newly developed non invasive techniques. Part II: functional evaluation].

The non-invasive evaluation of myocardial ischemia is a priority in cardiology. The preferred initial non-invasive test is exercise ECG, because of its high accessibility and its low cost. Stress radionuclide myocardial perfusion imaging or stress echocardiography are now routinely performed, and new non-invasive techniques such as perfusion-MRI, dobutamine stress-MRI or 82rubidium perfusion PET have recently gained acceptance in clinical practice. In the same time, an increasing attention has been accorded to the concept of myocardial viability in the decisional processes in case of ischemic heart failure. In this indication, MRI with late enhancement after intravenous injection of gadolinium and 18F-FDG PET showed an excellent diagnostic accuracy. This article will present these new imaging modalities and their accepted indications.

Three-dimensional ordered-subset expectation maximization iterative protocol for evaluation of left ventricular volumes and function by quantitative gated SPECT: a dynamic phantom study.

The purposes of this study were to characterize the performance of a 3-dimensional (3D) ordered-subset expectation maximization (OSEM) algorithm in the quantification of left ventricular (LV) function with (99m)Tc-labeled agent gated SPECT (G-SPECT), the QGS program, and a beating-heart phantom and to optimize the reconstruction parameters for clinical applications. METHODS: A G-SPECT image of a dynamic heart phantom simulating the beating left ventricle was acquired. The exact volumes of the phantom were known and were as follows: end-diastolic volume (EDV) of 112 mL, end-systolic volume (ESV) of 37 mL, and stroke volume (SV) of 75 mL; these volumes produced an LV ejection fraction (LVEF) of 67%. Tomographic reconstructions were obtained after 10-20 iterations (I) with 4, 8, and 16 subsets (S) at full width at half maximum (FWHM) gaussian postprocessing filter cutoff values of 8-15 mm. The QGS program was used for quantitative measurements. RESULTS: Measured values ranged from 72 to 92 mL for EDV, from 18 to 32 mL for ESV, and from 54 to 63 mL for SV, and the calculated LVEF ranged from 65% to 76%. Overall, the combination of 10 I, 8 S, and a cutoff filter value of 10 mm produced the most accurate results. The plot of the measures with respect to the expectation maximization-equivalent iterations (I x S product) revealed a bell-shaped curve for the LV volumes and a reverse distribution for the LVEF, with the best results in the intermediate range. In particular, FWHM cutoff values exceeding 10 mm affected the estimation of the LV volumes. CONCLUSION: The QGS program is able to correctly calculate the LVEF when used in association with an optimized 3D OSEM algorithm (8 S, 10 I, and FWHM of 10 mm) but underestimates the LV volumes. However, various combinations of technical parameters, including a limited range of I and S (80-160 expectation maximization-equivalent iterations) and low cutoff values (< or =10 mm) for the gaussian postprocessing filter, produced results with similar accuracies and without clinically relevant differences in the LV volumes and the estimated LVEF.

Robust volume-targeted balanced steady-state free-precession coronary magnetic resonance angiography in a breathhold at 3.0 Tesla: a reproducibility study.

BACKGROUND: Transient balanced steady-state free-precession (bSSFP) has shown substantial promise for noninvasive assessment of coronary arteries but its utilization at 3.0 T and above has been hampered by susceptibility to field inhomogeneities that degrade image quality. The purpose of this work was to refine, implement, and test a robust, practical single-breathhold bSSFP coronary MRA sequence at 3.0 T and to test the reproducibility of the technique. METHODS: A 3D, volume-targeted, high-resolution bSSFP sequence was implemented. Localized image-based shimming was performed to minimize inhomogeneities of both the static magnetic field and the radio frequency excitation field. Fifteen healthy volunteers and three patients with coronary artery disease underwent examination with the bSSFP sequence (scan time = 20.5 ± 2.0 seconds), and acquisitions were repeated in nine subjects. The images were quantitatively analyzed using a semi-automated software tool, and the repeatability and reproducibility of measurements were determined using regression analysis and intra-class correlation coefficient (ICC), in a blinded manner. RESULTS: The 3D bSSFP sequence provided uniform, high-quality depiction of coronary arteries (n = 20). The average visible vessel length of 100.5 ± 6.3 mm and sharpness of 55 ± 2% compared favorably with earlier reported navigator-gated bSSFP and gradient echo sequences at 3.0 T. Length measurements demonstrated a highly statistically significant degree of inter-observer (r = 0.994, ICC = 0.993), intra-observer (r = 0.894, ICC = 0.896), and inter-scan concordance (r = 0.980, ICC = 0.974). Furthermore, ICC values demonstrated excellent intra-observer, inter-observer, and inter-scan agreement for vessel diameter measurements (ICC = 0.987, 0.976, and 0.961, respectively), and vessel sharpness values (ICC = 0.989, 0.938, and 0.904, respectively). CONCLUSIONS: The 3D bSSFP acquisition, using a state-of-the-art MR scanner equipped with recently available technologies such as multi-transmit, 32-channel cardiac coil, and localized B0 and B1+ shimming, allows accelerated and reproducible multi-segment assessment of the major coronary arteries at 3.0 T in a single breathhold. This rapid sequence may be especially useful for functional imaging of the coronaries where the acquisition time is limited by the stress duration and in cases where low navigator-gating efficiency prohibits acquisition of a free breathing scan in a reasonable time period.

Imaging and therapy with monoclonal antibodies in non-hematopoietic tumors.

Although radiolabelled monoclonal antibodies are useful in tumor imaging, in our opinion their most important role is in the evaluation of the capacity of newly developed monoclonal antibodies to localize in tumors specifically. Intravenous injections of monoclonal antibody fragments, labelled with beta-emitting radionuclides, can completely eradicate large human colon carcinoma xenografts in nude mice whereas this is not achieved by unconjugated monoclonal antibodies. New strategies are being developed to make radioimmunotherapy applicable to carcinoma patients.

EEG Patterns and Imaging Correlations in Encephalopathy: Encephalopathy Part II.

SUMMARY:: The EEG patterns seen with encephalopathies can be correlated to cerebral imaging findings including head computerized tomography and MRI. Background slowing without slow-wave intrusion is seen with acute and chronic cortical impairments that spare subcortical white matter. Subcortical/white matter structural abnormalities or hydrocephalus may produce projected slow-wave activity, while clinical entities involving both cortical and subcortical regions (diffuse cerebral abnormalities) engender both background slowing and slow-wave activity. Triphasic waves are seen with hepatic and renal insufficiency or medication toxicities (e.g., lithium, baclofen) in the absence of a significant cerebral imaging abnormality, Conversely, subcortical/white matter abnormalities may facilitate the appearance of triphasic waves without significant hepatic, renal, or toxic comorbidities. More specific syndromes, such as Jakob-Creutzfeldt disease, autoimmune limbic encephalitis, autoimmune corticosteroid-responsive encephalopathy with thyroid autoimmunity, sepsis-associated encephalopathy, and acute disseminated encephalomyelitis, have imaging/EEG changes that are variable but which may include slowing and epileptiform activity. This overview highlighting EEG-imaging correlations may help the treating physician in the diagnosis, and hence the appropriate treatment, of patients with encephalopathy.

Combined functional and viability cardiac MR imaging in a single breathhold

The combination of cardiac viability and functional information enhances the identification of different heart tissues in the setting of ischemic heart disease. A method has recently been proposed for obtaining black-blood delayed-enhancement (DE) viability images using the stimulated-echo acquisition mode (STEAM) MRI pulse sequence in a single short breathhold. The method was validated against conventional inversion-recovery (IR) DE images for identifying regions of myocardial infarction (MI). The method was based on the acquisition of three consecutive images of the same anatomical slice. One image has T(1)-weighted contrast in which infarction appears bright. The two other images are used to construct an anatomical image of the heart, which is combined with the first image to produce a black-blood viability image. However, using appropriate modulation and demodulation frequencies, the latter two images bear useful information about myocardial deformation that results in a cardiac strain-encoding (SENC) functional image. In this work, a method is proposed for obtaining three consecutive SENC images in a single acquisition that can be combined to produce a composite image of the heart, which shows both functional and viability information. The proposed technique reduces scan time by one-half, compared with separate acquisitions of functional and viability images, and alleviates misregistration problems caused by separate breathholds.