Browsing by Subject "Image Enhancement"
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Item Open Access A 17-Year-Old Girl With Unilateral Headache and Double Vision.(Journal of investigative medicine high impact case reports, 2019-01) Rodriguez-Homs, Larissa G; Goerlitz-Jessen, Mark; Das, Samrat UTolosa-Hunt syndrome is characterized by a painful ophthalmoplegia secondary to a granulomatous inflammation in or adjacent to the cavernous sinus. Magnetic resonance imaging will show enhancement of the cavernous sinus and/or the orbital apex. Although this syndrome is extremely rare in children, it should be a diagnostic consideration in patients presenting with painful ophthalmoplegia with variable involvement of cranial nerves II to VI. The differential diagnosis for unilateral cavernous sinus lesion is broad, including vascular lesions (cavernous sinus thrombosis), inflammatory processes (sarcoidosis, autoimmune), neoplastic processes (schwannoma, lymphoma), as well as infectious etiologies. We describe a pediatric patient presenting with neurological symptoms from a unilateral cavernous sinus magnetic resonance imaging abnormality and the thorough diagnostic approach to arrive at the diagnosis of Tolosa-Hunt syndrome.Item Open Access Contrast in intracardiac acoustic radiation force impulse images of radiofrequency ablation lesions.(Ultrason Imaging, 2014-04) Eyerly, Stephanie A; Bahnson, Tristram D; Koontz, Jason I; Bradway, David P; Dumont, Douglas M; Trahey, Gregg E; Wolf, Patrick DWe have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 µm) than at ablated sites (6.06 ± 0.94 µm). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = -0.03 ± 0.28, CNR = 0.74 ± 0.68).Item Open Access Critical Review of Current Approaches for Echocardiographic Reproducibility and Reliability Assessment in Clinical Research.(Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography, 2016-12) Crowley, Anna Lisa; Yow, Eric; Barnhart, Huiman X; Daubert, Melissa A; Bigelow, Robert; Sullivan, Daniel C; Pencina, Michael; Douglas, Pamela SBackground
There is no broadly accepted standard method for assessing the quality of echocardiographic measurements in clinical research reports, despite the recognized importance of this information in assessing the quality of study results.Methods
Twenty unique clinical studies were identified reporting echocardiographic data quality for determinations of left ventricular (LV) volumes (n = 13), ejection fraction (n = 12), mass (n = 9), outflow tract diameter (n = 3), and mitral Doppler peak early velocity (n = 4). To better understand the range of possible estimates of data quality and to compare their utility, reported reproducibility measures were tabulated, and de novo estimates were then calculated for missing measures, including intraclass correlation coefficient (ICC), 95% limits of agreement, coefficient of variation (CV), coverage probability, and total deviation index, for each variable for each study.Results
The studies varied in approaches to reproducibility testing, sample size, and metrics assessed and values reported. Reported metrics included mean difference and its SD (n = 7 studies), ICC (n = 5), CV (n = 4), and Bland-Altman limits of agreement (n = 4). Once de novo estimates of all missing indices were determined, reasonable reproducibility targets for each were identified as those achieved by the majority of studies. These included, for LV end-diastolic volume, ICC > 0.95, CV < 7%, and coverage probability > 0.93 within 30 mL; for LV ejection fraction, ICC > 0.85, CV < 8%, and coverage probability > 0.85 within 10%; and for LV mass, ICC > 0.85, CV < 10%, and coverage probability > 0.60 within 20 g.Conclusions
Assessment of data quality in echocardiographic clinical research is infrequent, and methods vary substantially. A first step to standardizing echocardiographic quality reporting is to standardize assessments and reporting metrics. Potential benefits include clearer communication of data quality and the identification of achievable targets to benchmark quality improvement initiatives.Item Open Access Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: our 1 year experience.(Journal of applied clinical medical physics, 2012-07-05) Chang, Z; Bowsher, J; Cai, J; Yoo, S; Wang, Z; Adamson, J; Ren, L; Yin, FFAmerican Association of Physicists in Medicine (AAPM) task group (TG) 142 has recently published a report to update recommendations of the AAPM TG 40 report and add new recommendations concerning medical accelerators in the era of image-guided radiation therapy (IGRT). The recommendations of AAPM TG 142 on IGRT are timely. In our institute, we established a comprehensive imaging QA program on a medical accelerator based on AAPM TG 142 and implemented it successfully. In this paper, we share our one-year experience and performance evaluation of an OBI capable linear accelerator, Novalis Tx, per TG 142 guidelines.Item Open Access Intracardiac acoustic radiation force impulse (ARFI) and shear wave imaging in pigs with focal infarctions.(IEEE Trans Ultrason Ferroelectr Freq Control, 2013-08) Hollender, Peter; Bradway, David; Wolf, Patrick; Goswami, Robi; Trahey, GreggFour pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with focused acoustic radiation force (ARF) impulses and image the subsequent tissue response. Tissue displacement in response to the ARF excitation was calculated with a phase-based estimator, and transverse wave magnitude and velocity were each estimated at every depth. The excitation sequence was repeated rapidly, either in the same location to generate 40 Hz M-modes at a single steering angle, or with a modulated steering angle to synthesize 2-D displacement magnitude and shear wave velocity images at 17 points in the cardiac cycle. Both types of images were acquired from various views in the right and left ventricles, in and out of infarcted regions. In all animals, acoustic radiation force impulse (ARFI) and shear wave elasticity imaging (SWEI) estimates indicated diastolic relaxation and systolic contraction in noninfarcted tissues. The M-mode sequences showed high beat-to-beat spatio-temporal repeatability of the measurements for each imaging plane. In views of noninfarcted tissue in the diseased animals, no significant elastic remodeling was indicated when compared with the control. Where available, views of infarcted tissue were compared with similar views from the control animal. In views of the LVFW, the infarcted tissue presented as stiff and non-contractile compared with the control. In a view of the IVS, no significant difference was seen between infarcted and healthy tissue, whereas in another view, a heterogeneous infarction was seen to be presenting itself as non-contractile in systole.Item Open Access Intracardiac acoustic radiation force impulse imaging: a novel imaging method for intraprocedural evaluation of radiofrequency ablation lesions.(Heart Rhythm, 2012-11) Eyerly, Stephanie A; Bahnson, Tristram D; Koontz, Jason I; Bradway, David P; Dumont, Douglas M; Trahey, Gregg E; Wolf, Patrick DBACKGROUND: Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease postprocedure atrial fibrillation recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff RFA-treated myocardium. OBJECTIVE: To determine whether intraprocedure ARFI images can identify RFA-treated myocardium in vivo. METHODS: In 8 canines, an electroanatomical mapping-guided intracardiac echo catheter was used to acquire 2-dimensional ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the intracardiac echo transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, noncontiguous lesion, or contiguous lesion. For comparison, 3 separate reviewers confirmed RFA lesion presence and contiguity on the basis of functional conduction block at the imaging plane location on electroanatomical activation maps. RESULTS: Ten percent of ARFI images were discarded because of motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesions had 75.3% specificity and 47.1% sensitivity. CONCLUSIONS: Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation.Item Open Access Portable Pocket colposcopy performs comparably to standard-of-care clinical colposcopy using acetic acid and Lugol's iodine as contrast mediators: an investigational study in Peru.(BJOG : an international journal of obstetrics and gynaecology, 2018-09) Mueller, JL; Lam, CT; Dahl, D; Asiedu, MN; Krieger, MS; Bellido-Fuentes, Y; Kellish, M; Peters, J; Erkanli, A; Ortiz, EJ; Muasher, LC; Taylor, PT; Schmitt, JW; Venegas, G; Ramanujam, NObjective
Our goal was to develop a tele-colposcopy platform for primary-care clinics to improve screening sensitivity and access. Specifically, we developed a low-cost, portable Pocket colposcope and evaluated its performance in a tertiary healthcare centre in Peru.Design and setting
Images of the cervix were captured with a standard-of-care and Pocket colposcope at la Liga Contra el Cáncer in Lima, Peru.Population
Two hundred Peruvian women with abnormal cytology and/or human papillomavirus positivity were enrolled.Methods
Images were collected using acetic acid and Lugol's iodine as contrast agents. Biopsies were taken as per standard-of-care procedures.Main outcome measures
After passing quality review, images from 129 women were sent to four physicians who provided a diagnosis for each image.Results
Physician interpretation of images from the two colposcopes agreed 83.1% of the time. The average sensitivity and specificity of physician interpretation compared with pathology was similar for the Pocket (sensitivity = 71.2%, specificity = 57.5%) and standard-of-care (sensitivity = 79.8%, specificity = 56.6%) colposcopes. When compared with a previous study where only acetic acid was applied to the cervix, results indicated that adding Lugol's iodine as a secondary contrast agent improved the percent agreement between colposcopes for all pathological categories by up to 8.9% and the sensitivity and specificity of physician interpretation compared with pathology by over 6.0 and 9.0%, respectively.Conclusions
The Pocket colposcope performance was similar to that of a standard-of-care colposcope when used to identify precancerous and cancerous lesions using acetic acid and Lugol's iodine during colposcopy examinations in Peru.Tweetable abstract
The Pocket colposcope performance was similar to that of a standard-of-care colposcope when identifying cervical lesions.Item Open Access Target localization using scanner-acquired SPECT data.(Journal of applied clinical medical physics, 2012-05-10) Roper, Justin R; Bowsher, James E; Wilson, Joshua M; Turkington, Timothy G; Yin, Fang-FangTarget localization using single photon emission computed tomography (SPECT) and planar imaging is being investigated for guiding radiation therapy delivery. Previous studies on SPECT-based localization have used computer-simulated or hybrid images with simulated tumors embedded in disease-free patient images where the tumor position is known and localization can be calculated directly. In the current study, localization was studied using scanner-acquired images. Five fillable spheres were placed in a whole body phantom. Sphere-to-background 99mTc radioactivity was 6:1. Ten independent SPECT scans were acquired with a Trionix Triad scanner using three detector trajectories: left lateral 180°, 360°, and right lateral 180°. Scan time was equivalent to 4.5 min. Images were reconstructed with and without attenuation correction. True target locations were estimated from 12 hr SPECT and CT images. From the 12 hr SPECT scan, 45 sets of orthogonal planar images were used to assess target localization; total acquisition time per set was equivalent to 4.5min. A numerical observer localized the center of the targets in the 4.5 min SPECT and planar images. SPECT-based localization errors were compared for the different detector trajectories. Across the four peripheral spheres, and using optimal iteration numbers and postreconstruction smoothing, means and standard deviations in localization errors were 0.90 ± 0.25 mm for proximal 180° trajectories, 1.31 ± 0.51 mm for 360° orbits, and 3.93 ± 1.48 mm for distal 180° trajectories. This rank order in localization performance is predicted by target attenuation and distance from the target to the collimator. For the targets with mean localization errors < 2 mm, attenuation correction reduced localization errors by 0.15 mm on average. The improvement from attenuation correction was 1.0 mm on average for the more poorly localized targets. Attenuation correction typically reduced localization errors, but for well-localized targets, the detector trajectory generally had a larger effect. Localization performance was found to be robust to iteration number and smoothing. Localization was generally worse using planar images as compared with proximal 180° and 360° SPECT scans. Using a proximal detector trajectory and attenuation correction, localization errors were within 2 mm for the three superficial targets, thus supporting the current role in biopsy and surgery, and demonstrating the potential for SPECT imaging inside radiation therapy treatment rooms.