Volumetric Acquisition Research Articles

Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source.

Endoscopic optical coherence tomography (OCT) instruments are mostly side viewing and rely on at least one proximal scan, thus limiting accuracy of volumetric imaging and en face visualization. Previous forward-viewing OCT devices had limited axial scan speeds. We report a forward-viewing fiber scanning 3D-OCT probe with 900μm field of view and 5μm transverse resolution, imaging at 1MHz axial scan rate in the human gastrointestinal tract. The probe is 3.3mm diameter and 20mm rigid length, thus enabling passage through the endoscopic channel. The scanner has 1.8kHz resonant frequency, and each volumetric acquisition takes 0.17s with 2 volumes/s display. 3D-OCT and angiography imaging of the colon was performed during surveillance colonoscopy.

SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT examinations in a 320 detector-row cone-beam scanner.

Low-cost Volumetric Ultrasound by Augmentation of 2D Systems: Design and Prototype.

Conventional two-dimensional (2D) ultrasound imaging is a powerful diagnostic tool in the hands of an experienced user, yet 2D ultrasound remains clinically underutilized and inherently incomplete, with output being very operator dependent. Volumetric ultrasound systems can more fully capture a three-dimensional (3D) region of interest, but current 3D systems require specialized transducers, are prohibitively expensive for many clinical departments, and do not register image orientation with respect to the patient; these systems are designed to provide improved workflow rather than operator independence. This work investigates whether it is possible to add volumetric 3D imaging capability to existing 2D ultrasound systems at minimal cost, providing a practical means of reducing operator dependence in ultrasound. In this paper, we present a low-cost method to make 2D ultrasound systems capable of quality volumetric image acquisition: we present the general system design and image acquisition method, including the use of a probe-mounted orientation sensor, a simple probe fixture prototype, and an offline volume reconstruction technique. We demonstrate initial results of the method, implemented using a Verasonics Vantage research scanner.

Video rate volumetric Ca2+ imaging across cortex using seeded iterative demixing (SID) microscopy.

Light-field microscopy (LFM) is a scalable approach for volumetric Ca2+ imaging with high volumetric acquisition rates (up to 100 Hz). Although the technology has enabled whole-brain Ca2+ imaging in semi-transparent specimens, tissue scattering has limited its application in the rodent brain. We introduce seeded iterative demixing (SID), a computational source-extraction technique that extends LFM to the mammalian cortex. SID can capture neuronal dynamics in vivo within a volume of 900 × 900 × 260 μm located as deep as 380 μm in the mouse cortex or hippocampus at a 30-Hz volume rate while discriminating signals from neurons as close as 20 μm apart, at a computational cost three orders of magnitude less than that of frame-by-frame image reconstruction. We expect that the simplicity and scalability of LFM, coupled with the performance of SID, will open up a range of applications including closed-loop experiments.

Magnetic Resonance Imaging of Hip Neuropathies: Beyond the Sciatica: A Practical Approach

Neural entrapments in the hip area represent a challenging diagnosis due to the complexity, deep location, and variable distribution of pelvic nerves. This paper aims to perform an anatomic and pathologic review of neural entrapment syndromes involving the pudendal, obturator, lateral cutaneous femoral, and femoral nerves at the pelvis. Among the etiologies for pelvic neuropathies, besides idiopathic and expansive processes, extrinsic compression by normal anatomical structures is also frequent, which relights the importance of the critic constriction points on nerves pathway. High-field 3-Tesla (3-T) magnetic resonance neurography is considered the best image method for such imaging investigation. At MR imaging neural disease may be appreciated by alterations in nerve signal intensity, size, and morphology. For such evaluation, three-dimensional images with isotropic volumetric data acquisition both on T1 and STIR sequences should be performed, enabling post-processing imaging on workstations, which improves the diagnostic sensibility an enables early therapeutic procedures.

Imaging the dynamics of cardiac fiber orientation in vivo using 3D Ultrasound Backscatter Tensor Imaging

The assessment of myocardial fiber disarray is of major interest for the study of the progression of myocardial disease. However, time-resolved imaging of the myocardial structure remains unavailable in clinical practice. In this study, we introduce 3D Backscatter Tensor Imaging (3D-BTI), an entirely novel ultrasound-based imaging technique that can map the myocardial fibers orientation and its dynamics with a temporal resolution of 10 ms during a single cardiac cycle, non-invasively and in vivo in entire volumes. 3D-BTI is based on ultrafast volumetric ultrasound acquisitions, which are used to quantify the spatial coherence of backscattered echoes at each point of the volume. The capability of 3D-BTI to map the fibers orientation was evaluated in vitro in 5 myocardial samples. The helicoidal transmural variation of fiber angles was in good agreement with the one obtained by histological analysis. 3D-BTI was then performed to map the fiber orientation dynamics in vivo in the beating heart of an open-chest sheep at a volume rate of 90 volumes/s. Finally, the clinical feasibility of 3D-BTI was shown on a healthy volunteer. These initial results indicate that 3D-BTI could become a fully non-invasive technique to assess myocardial disarray at the bedside of patients.

MP18-18 THREE-DIMENSIONAL VS. TWO-DIMENSIONAL SHEAR-WAVE ELASTOGRAPHY OF THE TESTES – PRELIMINARY STUDY ON A HEALTHY COLLECTIVE

You have accessJournal of UrologyImaging/Radiology: Uroradiology III1 Apr 2017MP18-18 THREE-DIMENSIONAL VS. TWO-DIMENSIONAL SHEAR-WAVE ELASTOGRAPHY OF THE TESTES – PRELIMINARY STUDY ON A HEALTHY COLLECTIVE Julian Marcon, Matthias Trottmann, Johannes Ruebenthaler, Melvin D'Anastasi, Christian G. Stief, Maximilian F. Reiser, and Dirk Andre Clevert Julian MarconJulian Marcon More articles by this author , Matthias TrottmannMatthias Trottmann More articles by this author , Johannes RuebenthalerJohannes Ruebenthaler More articles by this author , Melvin D'AnastasiMelvin D'Anastasi More articles by this author , Christian G. StiefChristian G. Stief More articles by this author , Maximilian F. ReiserMaximilian F. Reiser More articles by this author , and Dirk Andre ClevertDirk Andre Clevert More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.628AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Shear wave elastography (SWE) is a newer technique for the determination of tissue elasticity. The measured velocity of generated shear waves (SWV) has been shown to correlate positively with tissue stiffness. SWE is integrated into many modern ultrasound systems and has been used in different organ systems. Two-dimensional SWE (2D SWE) of the testes has been found to be a useful tool in recent studies on healthy volunteers. Three-dimensional SWE (3D SWE) is the latest development and is made possible by generation of a multiplanar 3D map via volumetric acquisition using a special ultrasound transducer. This technique allows the assessment of tissue elasticity in a fully accessible 3D organ map. The aim of this preliminary study was to both evaluate the feasibility of 3D SWE and to compare 2D and 3D SWE standard values in the testes of healthy subjects. METHODS We examined the testes of healthy male volunteers (n=32) with a mean age of 51.06 ± 17.75 years (range 25-77 years) by B-mode ultrasound, 2D and 3D SWE techniques. Volunteers with a history of testicular pathologies were excluded. For all imaging procedures the SL15-4 linear transducer (bandwidth 4-15 MHz) as well as the SLV16-4 volumetric probe (bandwidth 4-16 MHz) of the Aixplorer®? ultrasound device (SuperSonic Imagine, Aix-en-Provence, France) were used. Seven regions of interest (ROI, Q-Box®?) within the testes were evaluated for SWV using both procedures. SWV values were described in m/s. Furthermore, we calculated testicular volume using both techniques and the formula for ellipsoid forms (LxWxHx0.523). Results were statistically evaluated using univariate analysis. RESULTS Mean SWV values were 1.05 m/s for the 2D SWE and 1.12 m/s for the 3D SWE.Comparisons of local areas delivered no statistically significant differences (p=0.11 to p=0.66), except for one ROI in the central portion of the coronal plane (p=0.03). Testicular volume was significanty higher by a mean of 1.72 ml when measured with 3D SWE (p=0.001). CONCLUSIONS In the assessment of testicular tissue 3D SWE proved to be a feasible diagnostic tool, while delivering similar values compared to the 2D method. It provided the examiner with a fully accessible three-dimensional map in a multiplanar view. Using 3D ultrasound a more precise testicular imaging, especially if combined with the display of tissue stiffness in SWE, is available and therefore could improve the diagnostic work-up of scrotal masses and male infertility. Further studies for a better understanding in the context of various testicular pathologies will be required. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e227-e228 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Julian Marcon More articles by this author Matthias Trottmann More articles by this author Johannes Ruebenthaler More articles by this author Melvin D'Anastasi More articles by this author Christian G. Stief More articles by this author Maximilian F. Reiser More articles by this author Dirk Andre Clevert More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Wavefront sensorless adaptive optics OCT with the DONE algorithm for in vivo human retinal imaging [Invited

In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications. We demonstrate the correction of five aberrations using 70 iterations of the DONE algorithm performed over 2.8 s of continuous volumetric OCT acquisition. Data acquired from an imaging phantom and in vivo from human research volunteers are presented.

High-resolution in vivo diffusion imaging of the human brain with generalized slice dithered enhanced resolution: Simultaneous multislice (gSlider-SMS).

To develop an efficient acquisition for high-resolution diffusion imaging and allow in vivo whole-brain acquisitions at 600- to 700-μm isotropic resolution. We combine blipped-controlled aliasing in parallel imaging simultaneous multislice (SMS) with a novel slab radiofrequency (RF) encoding gSlider (generalized slice-dithered enhanced resolution) to form a signal-to-noise ratio-efficient volumetric simultaneous multislab acquisition. Here, multiple thin slabs are acquired simultaneously with controlled aliasing, and unaliased with parallel imaging. To achieve high resolution in the slice direction, the slab is volumetrically encoded using RF encoding with a scheme similar to Hadamard encoding. However, with gSlider, the RF-encoding bases are specifically designed to be highly independent and provide high image signal-to-noise ratio in each slab acquisition to enable self-navigation of the diffusion's phase corruption. Finally, the method is combined with zoomed imaging (while retaining whole-brain coverage) to facilitate low-distortion single-shot in-plane encoding with echo-planar imaging at high resolution. A 10-slices-per-shot gSlider-SMS acquisition was used to acquire whole-brain data at 660 and 760 μm isotropic resolution with b-values of 1500 and 1800 s/mm2 , respectively. Data were acquired on the Connectome 3 Tesla scanner with 64-channel head coil. High-quality data with excellent contrast were achieved at these resolutions, which enable the visualization of fine-scale structures. The gSlider-SMS approach provides a new, efficient way to acquire high-resolution diffusion data. Magn Reson Med 79:141-151, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

3D ultrasound estimation of the effective volume for popliteal block at the level of division

Abstract Local anaesthetic injection between the tibial and commmon peroneal nerves within connective tissue sheath results in a predictable diffusion and allows for a reduction in the volume needed to achieve a consistent sciatic popliteal block. Using 3D ultrasound volumetric acquisition, we quantified the visible volume in contact with the nerve along a 5 cm segment. Methods We included 20 consecutive patients scheduled for bunion surgery. Ultrasound guided popliteal block was performed using a posterior, out of plane approach at the level of division of the sciatic nerve. Thirty mL of mepivacaine 1.5% and levobupivacaine 0.5% were slowly injected while assessing the injection pressure and the diffusion of the local anaesthetic. Volumetric acquisition was performed before and after the block to quantify the volume of the sciatic nerve and the volume of the surrounding hypoechoic halo contained inside the connective tissue in a 5 cm segment. Results All blocks were successful within 20 min after the injection. The total estimated volume contained inside the common connective tissue sheath was 6.8 ± 2.6 cm 3 . Of this, the volume of the halo surrounding the nerve was 4.4 ± 1.7 cm 3 and the volume inside the sciatic nerve was 2.4 ± 1.7 cm 3 . Conclusions The volume of local anaesthetic in close contact with the sciatic nerve can be estimated by volumetric acquisition. Our results suggest that the effective volume of local anaesthetic needed for a successful sciatic popliteal block could be reduced to less than 7 mL.

Three-dimensional vs. two-dimensional shear-wave elastography of the testes - preliminary study on a healthy collective.

Shear wave elastography (SWE) and its derivative Supersonic Shear Imaging (SSI) are newer techniques for the determination of tissue elasticity by measuring the velocity of generated shear waves (SWV), which correlates positively with tissue stiffness.The techniques are integrated into many modern ultrasound systems and have been examined in the evaluation of viscoelastic properties of different organ systems. Two-dimensional shear wave elastography (2D SWE) of the testes has been found to be a useful tool in recent studies which included the determination of standard values in healthy volunteers. Three-dimensional shear wave elastography (3D SWE) is the latest development in elastography and is made possible by generation of a multiplanar three-dimensional map via volumetric acquisition with a special ultrasound transducer. This technique allows the assessment of tissue elasticity in a three-dimensional, fully accessible organ map.The aim of this preliminary study was to both evaluate the feasibility of 3D SWE and to compare 2D and 3D SWE standard values in the testes of healthy subjects. We examined the testes of healthy male volunteers (n = 32) with a mean age of 51.06±17.75 years (range 25-77 years) by B-mode ultrasound, 2D and 3D SWE techniques in September of 2016. Volunteers with a history of testicular pathologies were excluded. For all imaging procedures the SL15-4 linear transducer (bandwidth 4-15 MHz) as well as the SLV16-4 volumetric probe (bandwidth 4-16 MHz) of the Aixplorer® ultrasound device (SuperSonic Imagine, Aix-en-Provence, France) were used. Seven regions of interest (ROI, Q-Box®) within the testes were evaluated for SWV using both procedures. SWV values were described in m/s. Results were statistically evaluated using univariateanalysis. Mean SWV values were 1.05 m/s for the 2D SWE and 1.12 m/s for the 3D SWE.Comparisons of local areas delivered no statistically significant differences (p = 0.11 to p = 0.66), except for the region in the central portion in the superior part of the coronal plane (p = 0.03). Testicular volume was significanty higher by a mean of 1.72 ml when measured with 3D SWE (p = 0.001). 3D SWE proved to be a feasible diagnostic tool in the assessment of testicular tissue, providing the examiner with a fully accessible three-dimensional map in a multiplanar or multislice view. With this technique a more precise testicular imaging - especially if combined with the display of tissue stiffness in SWE - is available and therefore could improve the diagnostic work-up of scrotal masses or the routine investigation of infertile men. Further studies for a better understanding in the context of various testicular pathologies will be required.

Sexual Dimorphism of Maxillary Sinus: A Morphometric Analysis using Cone Beam Computed Tomography.

Age and sex determination in forensic sciences are primary components of any skeletal analysis. As most bones used for sex determination are recovered in incomplete state, it is often necessary to use bones that are recovered intact e.g., the maxillary sinus. Cone Beam Computed Tomography (CBCT) can provide precise information about complex anatomical structures, as it is characterized by rapid volumetric image acquisition with high resolution. The present study was designed to evaluate the size and volume of Maxillary Sinus (MS) in determining gender by CBCT. Bilateral maxillary sinus images (left and right) were acquired for 100 patients (50 females and 50 males) and different parameters (width, length, height, area, perimeter and volume) were measured and evaluated. Mean and standard deviation of both maxillary sinuses measurements were calculated and compared. The data was subjected to discriminative statistical analysis and analysed using unpaired t-test. Comparison between male and female groups showed statistically insignificant differences on both the right and left sides with respect to the maxillary sinus length, height, area, volume and perimeter. However, the female group showed statistically significant higher values for left side MS width (p=0.041) and left side MS width can be used to determine gender with an overall accuracy of 60%. The final result of discriminative analysis shows that the ability of the maxillary sinus to identify gender was 68% in males and 74% in females with an overall accuracy of 71%. Maxillary sinus width can be used as an aid in forensic anthropology for gender determination.

Contour and Angle-Function Based Scoliosis Monitoring: Relaxing the Requirement on Image Quality in the Measurement of Spinal Curvature.

A method for measuring spinal curvature that provides a useful analog to the Cobb angle and is tolerant of degraded image quality is proposed. Conventional methods require a higher standard of discernibility for vertebra features and suffer high variability. Assumption is made that the natural representation of the spine for the purpose of scoliosis monitoring is that of a continuous curved contour rather than a series of discrete vertebral bodies with individual orientations. The angle that a tangent line to this contour makes with the vertical, expressed as a continuous function of height, is proposed as a metric for characterization of the curve. The Cobb angle can be approximated as the difference between the extrema of this function, and details of the function shape can provide additional markers for tracking curve variation and evolution. A method for deriving the angle function from coronal images of the spine is proposed, and both manual and automatic variants of the procedure are described. The method is applied to conventional coronal radiographs and to magnetic resonance (MR) coronal views derived from volumetric acquisitions of the spine. Included in the latter category is an image exhibiting poor discrimination of vertebra features due to motion artifacts. The method permits extraction of the curve and Cobb angles in all cases. Because the spine contour is discernible even in low quality images where vertebral endplates may be obscured or poorly contrasted from surrounding tissue, the approach offers improved reliability, applicability across imaging modalities, and, in the case of x-rays, the possibility of a reduced radiation dose. Moreover, since it relies on larger image features and exploits the continuity of the spine, the contour-based approach is expected to reduce the variability associated with Cobb angle measurement.

Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Symptomatic Uterine Fibroids and Normal Uterus: A Feasibility Study

Background: Dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) is a relatively new imaging technique that provides additional information on vascularity and permeability of the uterine tissues to improve decision making in patient management. Objectives: The purpose of this study was to obtain the quantitative DCE-MRI parameters of symptomatic uterine fibroids and compare to the parameters obtained from normal myometrium, endometrium, and cervix. Patients and Methods: Nineteen patients (aged 40 ± 5 years) with the clinical diagnosis of uterine fibroids were recruited. After routine MRI pelvis scan, DCE-MRI was performed using T1 volumetric liver acquisition with volume acceleration (LAVA) sequence. The data were post-processed using an independent DCE-MRI analysis software. ROI was drawn on the fibroid and the quantitative DCE-MRI parameters i.e. Ktrans (volume transfer between the blood plasma and extracellular fluid), Kep [flux rate constant between the extracellular extravascular space (EES) and blood plasma], Ve (EES fractional volume), and semi-quantitative parameters i.e. TTP (time to peak), and IAUGC (initial area under the gadolinium concentration-time curve) were determined. The patients then underwent hysterectomy and uterine fibroids were confirmed in all the patients by histopathology results. In the control group, fifteen healthy volunteers (aged 32 ± 6 years) who did not have uterine fibroid confirmed by sonography examination were recruited. The volunteers underwent the same DCE-MRI scan as the patients and the quantitative DCE-MRI parameters of the normal myometrium, endometrium and cervix were obtained. The DCE-MRI parameters from these two groups were then compared. Results: The median Ktrans in the myometrium, endometrium and cervix of the healthy volunteers were 0.26 ± 0.13, 0.20 ± 0.15, and 0.30 ± 0.13 min-1, respectively. No statistical significant difference was found in all the DCE-MRI parameters between the myometrium, endometrium and cervix of the healthy volunteers. The median Ktrans in fibroids was 0.50 ± 0.25 min-1. There were statistically significant differences (P < 0.05) found in Ktrans and Ve between the normal myometrium and fibroid tissue. Conclusions: The Ktrans and Ve of fibroid tissue were statistically significantly higher than those obtained from the normal myometrium, whereby the suggested cut-off values were 0.47 min-1 (sensitivity 64.7%, specificity 92.3%) and 0.62 (sensitivity 70.6%, specificity 78.6%), respectively. Quantitative DCE-MRI findings from this study may provide a foundation for assessment of other uterine pathologies.

Added Value of 3D Proton-Density Weighted Images in Diagnosis of Intracranial Arterial Dissection

BackgroundAn early and reliable diagnosis of intracranial arterial dissection is important to reduce the risk of neurological complication. The purpose of this study was to assess the clinical usefulness of three-dimensional high-resolution MRI (3D-HR-MRI) including pre- and post-contrast T1-weighted volumetric isotropic turbo spin echo acquisition with improved motion-sensitized driven equilibrium preparation (3D-iMSDE-T1) and proton-density weighted image (3D-PD) in detecting dissection and to evaluate the added value of 3D-PD in diagnosing intracranial arterial dissection.MethodsWe retrospectively recruited patients who underwent 3D-HR-MRI with clinical suspicion of arterial dissection. Among them, we selected patients who were diagnosed with definite dissection according to the Spontaneous Cervicocephalic Arterial Dissections Study criteria. For each patient, the presence of intimal flap, intramural hematoma, and vessel dilatation were evaluated independently by two neuroradiologists on each sequence. Interobserver agreement was assessed.ResultsSeventeen patients (mean age: 41 ± 10 [SD] years; 13 men) were diagnosed with definite dissection. The intimal flaps were more frequently detected on 3D-PD (88.2%, 15/17) than on 3D-iMSDE-T1 (29.4%, 5/17), and post-contrast 3D-iMSDE-T1 (35.3%, 6/17; P = 0.006 and P = 0.004, respectively). No significant difference was found in the detection rate of intramural hematomas (59–71%) and vascular dilatations (47%) on each sequence. Interobserver agreement for detection of dissection findings showed almost perfect agreement (k = 0.84–1.00), except for detection of intimal flaps on pre-contrast 3D-iMSDE-T1 (k = 0.62). After addition of 3D-PD to pre- and post-contrast 3D-iMSDE-T1, more patients were diagnosed with definite dissection with the initial MRI (88.2% vs. 47.1%; P = 0.039).ConclusionsThe intimal flap might be better visualized on the 3D-PD sequence than the 3D-iMSDE-T1 sequences, allowing diagnosis of definite dissection without follow-up imaging.

Intracranial arterial wall enhancement using gadolinium-enhanced 3D black-blood T1-weighted imaging

PurposeWe investigated the enhancement of the intracranial arterial walls with gadolinium-enhanced, black-blood three-dimensional T1-weighted imaging (Gd-3DBB) by using an improved motion-sensitized driven-equilibrium (iMSDE)—prepared volumetric isotropic turbo spin-echo acquisition (VISTA). MethodsA total of 115 patients underwent FLAIR, 3D-TOF-MRA and Gd-3DBB with a 1.5-T scanner. The degree and distribution of the arterial wall enhancement on Gd-3DBB was assessed. The association of the degree of wall enhancement with brain infarction/ischemic lesions on FLAIR, luminal changes on 3D-TOF-MRA, and cardiovascular risk factors (CVRFs) was investigated by univariate and multiple logistic regression analyses. ResultsStrong enhancement of the arterial walls was observed in 77 vertebral arteries (33.5%), 4 basilar arteries (3.5%), 31 supraclinoid internal carotid arteries (ICAs) (13.5%) and 8 middle cerebral arteries (3.5%). In addition, 221 intrapetrous ICAs (96.1%) showed strong enhancement. After adjusting for confounding factors, multivariate analyses showed that the patient age was independently associated with the strong wall enhancement of the arteries for both the posterior (OR, 1.088; 95% CI, 1.034–1.146) and the anterior circulation (OR, 1.098, 95% CI 1.029–1.172). In addition, the presence of the supratentorial brain infarctions was independently associated with the strong wall enhancement in the anterior circulation excluding the intrapetrous ICAs (OR, 4.097; 95% CI, 1.483–11.319). ConclusionsAlthough the arterial wall enhancement on the Gd-3DBB probably reflects normal aging, the enhancement in the anterior circulation might be related to brain infarctions. On the other hand, the intrapetrous ICA enhancement is considered a nonspecific finding and should not be mistaken for arterial pathologies such as atherosclerosis or arteritis.

Estimación del volumen de anestésico local en contacto con el nervio ciático en el bloqueo poplíteo

Local anaesthetic injection between the tibial and commmon peroneal nerves within connective tissue sheath results in a predictable diffusion and allows for a reduction in the volume needed to achieve a consistent sciatic popliteal block. Using 3D ultrasound volumetric acquisition, we quantified the visible volume in contact with the nerve along a 5cm segment. MethodsWe included 20 consecutive patients scheduled for bunion surgery. Ultrasound guided popliteal block was performed using a posterior, out of plane approach at the level of división of the sciatic nerve. Thirty ml of mepivacaine 1.5% and levobupivacaine 0.5% were slowly injected while assessing the injection pressure and the diffusion of the local anaesthetic. Volumetric acquisition was performed before and after the block to quantify the the volume of the sciatic nerve and the volume of the surrounding hypoechoic halo contained inside the connective tissue in a 5cm segment. ResultsAll blocks were successful within 20min after the injection. The total estimated volume contained inside the common connective tissue sheath was 6.8±2.6cm3. Of this, the volume of the halo sorrounding the nerve was 4.4±1.7cm3 and the volume inside the sciatic nerve was 2.4±1.7cm3. ConclusionsThe volume of local anaesthetic in close contact with the sciatic nerve can be estimated by volumetric acquisition. Our results suggest that the effective volume of local anaesthetic needed for a successful sciatic popliteal block could be reduced to less than 7ml.

Emerging Clinical Applications of 4D Flow MR in the Heart and Aorta

Review the current literature, focusing on potential clinical applications of time-resolved 3-dimensional phase contrast imaging (4D flow) in the thorax. Magnetic resonance imaging has become an important diagnostic tool in the evaluation of the heart and great vessels, complimenting echocardiography in routine clinical practice. Advances in 4D flow now allow for comprehensive modeling of blood flow in the thorax in a single ECG-gated and respiratory-gated volumetric acquisition. 4D Flow modeling of preferential flow through shunts, eccentric jets related to valvular disease, helical flow in aneurysms, shear wall stress around atherosclerotic plaque, and pulse wave pressures within the aorta is now possible, and may lead to improved prognostication and management of complex cardiovascular pathology. The physiologic data obtained with 4D flow MR has provided new insight into a wide range of cardiovascular pathology, from congenital heart disease, bicuspid aortopathy, and aortic coarction to aortic aneurysms, atherosclerotic plaque, and aortic dissection.

3D T1-weighted black blood sequence at 3.0 Tesla for the diagnosis of cervical artery dissection

ObjectiveWe aimed to investigate the value of three-dimensional (3D) T1 volumetric isotropic turbo spin echo acquisition (VISTA) in the diagnosis of cervical artery dissection (CAD).MethodsWe prospectively included patients who were...

Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography.

Volumetric acquisition with anterior segment optical coherence tomography (ASOCT) is necessary to obtain accurate representations of the tissue structure and to account for asymmetries of the anterior eye anatomy. Additionally, recent interest in imaging of anterior segment vasculature and aqueous humor flow resulted in application of OCT angiography techniques to generate en face and 3D micro-vasculature maps of the anterior segment. Unfortunately, ASOCT structural and vasculature imaging systems do not capture volumes instantaneously and are subject to motion artifacts due to involuntary eye motion that may hinder their accuracy and repeatability. Several groups have demonstrated real-time tracking for motion-compensated in vivo OCT retinal imaging, but these techniques are not applicable in the anterior segment. In this work, we demonstrate a simple and low-cost pupil tracking system integrated into a custom swept-source OCT system for real-time motion-compensated anterior segment volumetric imaging. Pupil oculography hardware coaxial with the swept-source OCT system enabled fast detection and tracking of the pupil centroid. The pupil tracking ASOCT system with a field of view of 15 x 15 mm achieved diffraction-limited imaging over a lateral tracking range of +/- 2.5 mm and was able to correct eye motion at up to 22 Hz. Pupil tracking ASOCT offers a novel real-time motion compensation approach that may facilitate accurate and reproducible anterior segment imaging.