Alternative Imaging Technique Research Articles

Oblique Chest X-Ray: An Alternative Way to Detect Pneumothorax.

Purpose: To identify occult pneumothorax with oblique chest X-ray (OCXR) in clinically suspected patients.Methods: In this retrospective study, we examined 1082 adult multitrauma patients who were admitted to our emergency service between January 2016 and January 2017. Clinical findings that suggest occult pneumothorax were rib fracture, flail chest, chest pain, subcutaneous emphysema, abrasion or ecchymosis and moderate to severe hypoxia in clinical parameters. All of these patients underwent anteroposterior chest X-ray (APCXR), but no pneumothorax could be detected. Upon this, OCXR was performed using mobile X-ray equipment.Results: Traumatic pneumothorax was observed in 421 (38.9%) of 1082 patients. We applied OCXR to 26 multitrauma patients. Occult pneumothorax was evaluated at 22 patients (2.03%) in 1082 multitrauma patients. The 22 patients who had multitrauma occult pneumothorax on OCXR were internated at intensive care unit (ICU) and follow-up was done using OCXR and APCXR.Conclusions: OCXR can be an alternative imaging technique to identify occult pneumothorax in some trauma patients at emergency room and also follow period at ICU.

Subdermal Ultrasound Contrast Agent Injection for Sentinel Lymph Node Identification: An Analysis of Safety and Contrast Agent Dose in Healthy Volunteers.

Mapping of the lymphatic chain for identification of the sentinel lymph node (SLN) is an important aspect of predicting outcomes for patients with breast cancer, and it is usually performed as an intraoperative procedure using blue dye and/or radiopharmaceutical agents. Recently, the use of contrast-enhanced ultrasound (CEUS) has been proposed as an alternative imaging technique for this mapping. The objective of this study was to evaluate the use of subdermal administration of the ultrasound (US) contrast agent Sonazoid (GE Healthcare, Oslo, Norway) in terms of patient safety and to select the dose to be used for lymphatic applications in humans. This study was performed in 12 female volunteers who received bilateral subdermal injections of Sonazoid (1 or 2 mL dose) in the mid-upper outer quadrant of their breasts at 2 different time points. Contrast-enhanced US examinations were performed 0, 0.25, 0.5, 1, 2, 4, 6, and 24 hours after injection to identify SLNs. Sentinel lymph nodes were identified within the first hour after injection as enhanced structures, and there was no significant difference by dose in the number of SLNs identified (P = .74). The volunteers only had minor adverse experiences (AEs) that resolved completely without intervention by study completion. The subdermal use of Sonazoid in this study showed only minor local and nonsignificant AEs that were completely resolved without any intervention. Two different doses were compared with no significant differences observed between them. Hence, the lower dose studied (1 mL) was selected for use in future clinical studies.

The role of sentinel lymph node mapping in small animal veterinary medicine: A comparison with current approaches in human medicine.

The relevance of regional lymph node (LN) assessment to quantify the metastatic spread of cancer is well recognized in veterinary oncology. Evaluation of LNs is critical for tumour staging. However, sampling the correct LN may not be possible without sentinel lymph node (SLN) mapping. Methods for diagnostic imaging and intraoperative detection of SLNs are well established in human medicine, in particular, the combination of lymphoscintigraphy and intraoperative application of blue dyes. Nevertheless, alternative imaging techniques are available and have gained increasing interest. Successful implementation of these techniques in dogs have been reported in both clinical and experimental studies. This review aims to provide an overview of SLN mapping techniques in human and veterinary medicine.

Feasibility, Accuracy, and Reproducibility of Aortic Annular and Root Sizing for Transcatheter Aortic Valve Replacement Using Novel Automated Three-Dimensional Echocardiographic Software: Comparison with Multi–Detector Row Computed Tomography

In transcatheter aortic valve replacement (TAVR), multi-detector row computed tomography (MDCT) is currently the standard imaging modality for correct prosthesis sizing, despite risks of radiation and contrast-induced renal injury. Three-dimensional (3D) transesophageal echocardiography (TEE) has been proposed as a potential alternative imaging technique, and recently, automated 3D transesophageal echocardiographic software (Aortic Valve Navigator [AVN], an unreleased prototype from Philips) has been developed for assessment of the aortic annulus and root. The aim of this study was to assess the feasibility, accuracy, and reproducibility of AVN measurements in TAVR candidates by performing a comparison with MDCT. In 150 patients with severe, symptomatic aortic stenosis referred for TAVR, data on aortic annular and root dimensions prospectively acquired using 3D TEE and MDCT were retrospectively analyzed. Image quality on 3D TEE and the duration of analysis with AVN were recorded, as well as the aortic valve Agatston score on MDCT. Data were obtained using 3D TEE and MDCT in 100% of patients for aortic annular dimensions and in 89% for aortic root dimensions. The mean duration of analysis using AVN was 4.2±1.0min, but it was significantly shorter with better 3D echocardiographic image quality and lower Agatston score on MDCT. Correlation of measurements between 3D TEE and MDCT was good to excellent for all anatomic locations (sinotubular junction mean diameter, R=0.71; sinus of Valsalva mean diameter, R=0.87; aortic annular mean diameter, R=0.75; aortic annular perimeter, R=0.83; aortic annular area, R=0.91), with low inter- and intraobserver variability (intraclass correlation coefficient≥0.93 and r≥0.90 for all locations). Comparison based on conventional prosthesis sizing charts yielded excellent agreement in prosthesis size choice (κ=0.90). New automated 3D transesophageal echocardiographic software allows accurate modeling and reproducible quantification of aortic annular and root dimensions with high feasibility. An excellent correlation between measurements with AVN and MDCT and agreement in prosthesis sizing suggests the use of AVN in clinical practice as potential alternative to MDCT before TAVR.

Contrast-enhanced US Assessment of Focal Liver Lesions in Children.

Ultrasonography (US) is often the first line of imaging for the examination of children suspected of having liver lesions. However, gray-scale US with color Doppler imaging has limitations. The use of US contrast agents has recently been approved by the U.S. Food and Drug Administration (FDA). Compared with other imaging modalities, contrast material-enhanced US (CEUS) enables the assessment of contrast enhancement patterns with a higher temporal resolution and is therefore becoming a valuable alternative imaging technique. CEUS is advantageous owing to its high safety profile; lower cost, compared with the costs of conventional contrast-enhanced computed tomographic and magnetic resonance imaging examinations; reliability; and reproducibility. Furthermore, US examinations obviate the use of sedation, ionizing radiation, and iodinated or gadolinium-based contrast agents. All of these are desirable attributes for an imaging examination for children, the most vulnerable of patients. Focal liver lesions in children are commonly discovered incidentally, and this can pose a dilemma in terms of diagnosis and management. Owing to the FDA's recent approval of the use of a specific US contrast agent for evaluation of focal liver lesions in pediatric patients, CEUS can now be used as a problem-solving tool that complements conventional imaging examinations and aids in the follow-up of lesions. The temporal resolution with CEUS enables US images to readily depict the real-time internal vascularity of a lesion. The characterization of a lesion during different phases of enhancement improves diagnostic confidence and treatment. In this article, the authors review the composition, physiologic properties, and safety profile of CEUS; describe the technique for performing CEUS; and highlight the utility of this examination in the assessment of common focal liver lesions in children. Online supplemental material is available for this article. ©RSNA, 2017.

Abstract 3262: Alternative strategies of screening and surveillance of patients with Von-Hippel Lindau syndrome to reduce radiation exposure and potential subsequent cancer risk

Abstract Background: Von-Hippel Lindau (VHL) syndrome is a rare genetic disorder that predisposes individuals to benign and malignant tumors, including pancreatic neuroendocrine tumors and renal cell carcinoma. Guidelines recommend abdominal Computed Tomography (CT) scans to be performed every one or two years starting in adolescence or young adulthood for screening or surveillance for these tumors. Objective: To assess radiation exposures resulting from alternative strategies of screening and surveillance by abdominal CT scans, and projecting potential cancer risks subsequent to these exposures. Methods: Organ radiation doses were estimated using a dedicated computational solution for CT dosimetry, on the basis of protocols routinely used at one U.S. cancer research center in 2012-2015. Subsequent Lifetime Attributable Risks (LARs) of cancer incidence were projected for lifelong nonsmokers, using a dedicated radiation risk assessment tool and accounting for the reduced life expectancy of individuals diagnosed with VHL. We assumed additive effects between VHL gene mutation and radiation exposures. Results: Based on a standard CT protocol, annual scans over a lifetime starting at age 15 are associated with cumulative colon doses of 1.8 Gy at age 30, 3.8 Gy at age 50. The associated LARs of cancer incidence would be 1–2% at age 50, and 11–32% at age 80. Delaying age at screening start to 21 years would reduce the projected risks to <1% at age 50 and <15% at age 80. A frequency of one scan every two years (as used for surveillance of cystic pancreatic lesions) would be associated with LARs of <1% at age 50 and <10% at age 80. The current use of a new CT protocol (dual energy virtual non-contrast CT) at the department would reduce radiation exposures and potential subsequent risks by more than 50%. Conclusion: Annual CT screening and surveillance for pancreatic and renal tumors in VHL patients can be associated with high radiation exposures. When Magnetic Resonance Imaging is not appropriate as an alternative imaging technique, delaying age at surveillance start or reducing the frequency of CT scans could significantly reduce the potential radiation-related risks, provided that these strategies remain beneficial for patients. Optimized CT protocols can also dramatically reduce radiation exposures. The present study is currently extended to confirm our dose estimates based on CT protocols against individual radiology data, and consider other genetic syndromes. Ultimately, this study should help defining surveillance strategies with optimal risk-benefit balance. Citation Format: Neige MY Journy. Alternative strategies of screening and surveillance of patients with Von-Hippel Lindau syndrome to reduce radiation exposure and potential subsequent cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3262. doi:10.1158/1538-7445.AM2017-3262

Value of quantitative magnetic resonance imaging T1-relaxometry in predicting contrast-enhancement in glioblastoma patients.

SUMMARIZING THE IMPORTANCE OF THE STUDYThe repetitive usage of gadolinium-based contrast agents (GBCA) is critical for magnetic resonance imaging (MRI) evaluation of tumor burden in glioblastoma patients. It is also a crucial tool for determination of radiographical response to treatment. GBCA injection, however, comes with a 2.4% rate of adverse events including life-threatening conditions such as nephrogenic systemic fibrosis (NSF). Moreover, GBCA have been shown to be deposited in brain tissue of patients even with an intact blood-brain barrier (BBB). The present study explores quantitative T1 relaxometry as an alternative non-invasive imaging technique detection of tumor burden and determination of radiographical response. This technique exploits specific properties of brain tissue with impaired BBB. With a sensitivity and specificity as high as 86% and 80%, respectively, quantitative T1-relaxometry allows for detecting contrast-enhancing areas without the use of GBCA. This method could make it unnecessary to subject patients to the risk of adverse events associated with the use of GBCA. Nonetheless, a large-scale analysis is needed to confirm our findings.BackgroundGadolinium-based contrast agents (GBCA) are crucial for magnetic resonance imaging (MRI)-based evaluation of tumor burden in glioblastoma (GBM). Serious adverse events of GBCA, even though uncommon, and gadolinium deposition in brain tissue could be avoided by novel imaging techniques not requiring GBCA. Altered tissue composition in areas with impaired blood-brain-barrier also alters the quantified T1 relaxation time (qT1), so that qT1 analysis could replace GBCA-based MRI for the analysis of tumor burden and response.MethodsAs a part of a prospective pilot MRI-relaxometry trial, patients with newly-diagnosed GBM who relapsed under standard radiochemotherapy were selected for this study. At recurrence, subtraction of qT1 maps pre and post-GBCA application (ΔqT1 maps) was used to determine areas of contrast-enhancement. With the contrast-enhancement on ΔqT1 maps as reference, ROC analysis served to detect an optimal qT1 cut-off on qT1 maps prior to GBCA to distinguish between contrast-enhancing tissue and its surroundings.ResultsTen patients were included. A qT1 value >2051ms predicted contrast-enhancing tumor tissue with a sensitivity of 86% and specificity of 80% (AUC, 0.92; p<0.0001). Interestingly, qT1 prolongation >2051 ms that did not overlap with contrast-enhancing area transformed into contrast-enhancement later on (n=4).ConclusionT1-relaxometry may be a useful technique to assess tissue properties equivalent to contrast-enhancement without the need for GBCA application. It may also provide information on sites with future tumor progression. Nonetheless, large-scale studies are needed to confirm these findings.

Avances en el diagnóstico por imagen de la endocarditis infecciosa izquierda

Infective endocarditis remains a clinical condition that requires early detection due to its high mortality rate. Diagnosis is based on clinical, microbiological and echocardiographic findings. Nevertheless, in some scenarios, such as prosthetic endocarditis, the diagnostic performance of echocardiography is limited. For this reason, recent clinical practice guidelines recommend the use of alternative imaging techniques to assist in the evaluation of doubtful cases. Three-dimensional transesophageal echocardiography has shown to be useful in improving the accuracy to measure and locate the signs of endocarditis. Likewise, due to the absence of the acoustic window limitation, cardiac computed tomography has become a valuable technique to evaluate peri-annular complications of endocarditis. Several radiotracers have been used in nuclear medicine to detect the inflammatory/infectious activity in endocarditis. Even though positron emission tomography with 18-fluorodeoxyglucose has demonstrated an outstanding sensitivity to visualize signs of infection in prosthetic valves, it still has not been shown to be as useful in native valves. Although scintigraphy with labelled leucocytes is a laborious technique, it has shown an excellent specificity in previous studies. Finally, there is no current evidence to support the routine use of cardiac magnetic resonance in endocarditis; nevertheless, tissue characterisation is an interesting research area.

Peering through the flames: imaging techniques for reacting aluminum powders.

Combusting metals burn at high temperatures and emit high-intensity radiation in the visible spectrum, which can oversaturate regular imaging sensors and obscure the field of view. Filtering the luminescence can result in limited information and hinder thorough combustion characterization. A method for "seeing through the flames" of a highly luminescent aluminum powder reaction is presented using copper vapor laser (CVL) illumination, synchronized with a high-speed camera. A statistical comparison of combusting aluminum particle agglomerates imaged using various filtration techniques shows the effectiveness of the high-speed camera with a CVL diagnostic approach. When ignited by an electrically induced plasma, aluminum particles are entrained as solid agglomerates that rotate about their centers of mass and are surrounded by emitted, burning gases. The average agglomerate diameter appears to be 160 μm when viewed with standard illumination and a high-speed camera. However, a significantly reduced diameter of 50 μm is recorded when imaged with CVL illumination coupled with a high-speed camera and a 511 nm notch filter. These results indicate alternative imaging techniques are required to resolve the complexities of metal particle combustion.

Reduced Frontal Activations at High Working Memory Load in Mild Cognitive Impairment: Near-Infrared Spectroscopy

Background: Some functional magnetic resonance imaging studies have reported altered activations in the frontal cortex during working memory (WM) performance in individuals with mild cognitive impairment (MCI), but the findings have been mixed. The objective of the present study was to utilize near-infrared spectroscopy (NIRS), an alternative imaging technique, to examine neural processing during WM performance in individuals with MCI. Methods: Twenty-six older adults with MCI (7 males; mean age 69.15 years) were compared with 26 age-, gender-, handedness-, and education-matched older adults with normal cognition (NC; 7 males; mean age 68.87 years). All of the participants undertook an n-back task with a low (i.e., 0-back) and a high (i.e., 2-back) WM load condition while their prefrontal dynamics were recorded by a 16-channel NIRS system. Results: Although behavioral results showed that the two groups had comparable task performance, neuroimaging results showed that the MCI group, unlike the NC group, did not exhibit significantly increased frontal activations bilaterally when WM load increased. Compared to the NC group, the MCI group had similar frontal activations at low load (p > 0.05 on all channels) but reduced activations at high load (p < 0.05 on 4 channels), thus failing to demonstrate WM-related frontal activations (p < 0.05 on 9 channels). In addition, we found a positive correlation between the left WM-related frontal activations and WM ability primarily in the NC group (r_s = 0.42, p = 0.035), suggesting a relationship between frontal hypoactivation and WM difficulties. Conclusion: The present findings suggest the presence of frontal dysfunction that is dependent on WM load in individuals with MCI.

Diagnosis of Aortic Graft Infection: A Case Definition by the Management of Aortic Graft Infection Collaboration (MAGIC)

The management of aortic graft infection (AGI) is highly complex and in the absence of a universally accepted case definition and evidence-based guidelines, clinical approaches and outcomes vary widely. The objective was to define precise criteria for diagnosing AGI. A process of expert review and consensus, involving formal collaboration between vascular surgeons, infection specialists, and radiologists from several English National Health Service hospital Trusts with large vascular services (Management of Aortic Graft Infection Collaboration [MAGIC]), produced the definition. Diagnostic criteria from three categories were classified as major or minor. It is proposed that AGI should be suspected if a single major criterion or two or more minor criteria from different categories are present. AGI is diagnosed if there is one major plus any criterion (major or minor) from another category. (i) Clinical/surgical major criteria comprise intraoperative identification of pus around a graft and situations where direct communication between the prosthesis and a nonsterile site exists, including fistulae, exposed grafts in open wounds, and deployment of an endovascular stent-graft into an infected field (e.g., mycotic aneurysm); minor criteria are localized AGI features or fever≥38°C, where AGI is the most likely cause. (ii) Radiological major criteria comprise increasing perigraft gas volume on serial computed tomography (CT) imaging or perigraft gas or fluid (≥7 weeks and ≥3 months, respectively) postimplantation; minor criteria include other CT features or evidence from alternative imaging techniques. (iii) Laboratory major criteria comprise isolation of microorganisms from percutaneous aspirates of perigraft fluid, explanted grafts, and other intraoperative specimens; minor criteria are positive blood cultures or elevated inflammatory indices with no alternative source. This AGI definition potentially offers a practical and consistent diagnostic standard, essential for comparing clinical management strategies, trial design, and developing evidence-based guidelines. It requires validation that is planned in a multicenter, clinical service database supported by the Vascular Society of Great Britain & Ireland.

Sparse tomographic acoustic imaging for environmental noise-source mapping

Environmental noise has become a major problem in large cities, increasing health risks for the urban population. Current methods are overly expensive for city-wide noise-monitoring as they generally require dense deployment of fixed microphones for noise-level measurements. We present here alternative sparse tomographic acoustic imaging techniques using arrays with relatively few number of microphones for large-region acoustic noise mapping. We first demonstrate that the locations and sound pressure levels of fixed noise sources sparsely located in a large field are recovered by collecting acoustic data at multiple locations with a portable microphone array for tomographic reconstruction. We then introduce a nonstationary tomographic imaging approach using fixed microphone arrays, which can also capture the intermittent changes in the acoustic field due to transient and/or moving noise sources. We test both the sparse static and dynamic imaging models with acoustic measurements collected with a circular microphone array mounted on an electric vehicle and two prepositioned circular arrays, respectively. The experimental results show the promise of the proposed methodology for low-cost and time-efficient large-scale noise-monitoring.

Visualization of the Internal Structure of Volcanoes with Cosmic-ray Muons

High-energy muons that are produced via the reaction between primary cosmic rays and the Earth’s atmosphere can be used as a radiographic probe to explore the density distribution in gigantic objects including shallow parts of a volcano’s interior. This new subterranean imaging technique is called muography. So far, muographic results have been acquired from eight volcanoes around the world as well as various targets including limestone caves, fault zones, industrial plants, and historical ruins. Taking all of the observational data together, it appears that muography can serve as a new and alternative high-resolution imaging technique, providing a fresh approach to Earth studies. This review describes observational studies in which muography has been used to explore the Earth’s interior. Particular attention is paid to muography of magma convection and pathways in volcanoes around the world. The results are summarized here, and an outlook regarding anticipated future observations is briefly discussed.

On the use of knee functional calibration to determine the medio-lateral axis of the femur in gait analysis: Comparison with EOS biplanar radiographs as reference

Accurate calibration of the medio-lateral axis of the femur is crucial for clinical decision making based on gait analysis. This study proposes a protocol utilizing biplanar radiographs to provide a reference medio-lateral axis based on the anatomy of the femur. The biplanar radiographs allowed 3D modelling of the bones of the lower limbs and the markers used for motion capture, in the standing posture. A comprehensive analysis was performed and results from biplanar radiographs were reliable for 3D marker localization (±0.35mm) and for 3D localization of the anatomical landmarks (±1mm), leading to a precision of 1° for the orientation of the condylar axis of the femur and a 95% confidence interval of ±3° after registration with motion capture data. The anatomical condylar axis was compared to a conventional, marker-based, axis and three functional calibration techniques (axis transformation, geometric axis fit and DynaKAD). Results for the conventional method show an average difference with the condylar axis of 15° (SD: 6°). Results indicate DynaKAD functional axis was the closest to the anatomical condylar axis, mean: 1° (SD: 5°) when applied to passive knee flexion movement. However, the range of the results exceeded 15° for all methods. Hence, the use of biplanar radiographs, or an alternative imaging technique, may be required to locate the medio-lateral axis of the femur reliably prior to clinical decision making for femur derotational osteotomies.

Ultrasonography and Low-field Magnetic Resonance Imaging of the Common Calcanean Tendon in a Rabbit Model for Tendinopathy Research: a Descriptive Study of Normal Anatomy.

In spite of recent advances in treatment protocols, tendinopathies continue to challenge orthopaedists and surgeons. Due to the complexity of both tendon injuries and the healing processes, animal models are essential for addressing fundamental questions in tendinopathy research. Diagnostic imaging could contribute to the evaluation of animal models, thus providing information, which could be translated to human tendinopathies. The objective of our study was to evaluate in situ appearance of the rabbit common calcanean tendon with ultrasonography and magnetic resonance imaging. Additionally, we sought to assess and compare the feasibility and usefulness of these techniques in a rabbit model while focusing on the imaging of the particular structures involved in calcaneal tendon disorders. Eight California rabbits were used for post-mortem sonographic and low-field magnetic resonance examination. Morphometry was performed on longitudinal sonograms and sagittal MRI scans. The craniocaudal diameter of the tendon was measured at four points of interest. Ultrasonography and magnetic resonance provided good visualisation of the tendon origin, the paratenon and the pre-Achilles fat pad. Magnetic resonance images presented in more detail the structure of the calcaneal insertion. Both modalities failed to visualise the individual components of the common calcanean tendon and the bursa of the calcaneal tendon. Statistical analysis of measurements obtained showed that the craniocaudal diameter of the common calcanean tendon in a rabbit increases significantly with a growing length from the calcaneal tuber. Both magnetic resonance and ultrasonography are feasible, and should be considered complementary, not alternative imaging techniques in a rabbit common calcanean tendon model.

Improvement of material decomposition and image quality in dual-energy radiography by reducing image noise

Although digital radiography has been widely used for screening human anatomical structures in clinical situations, it has several limitations due to anatomical overlapping. To resolve this problem, dual-energy imaging techniques, which provide a method for decomposing overlying anatomical structures, have been suggested as alternative imaging techniques. Previous studies have reported several dual-energy techniques, each resulting in different image qualities. In this study, we compared three dual-energy techniques: simple log subtraction (SLS), simple smoothing of a high-energy image (SSH), and anti-correlated noise reduction (ACNR) with respect to material thickness quantification and image quality. To evaluate dual-energy radiography, we conducted Monte Carlo simulation and experimental phantom studies. The Geant 4 Application for Tomographic Emission (GATE) v 6.0 and tungsten anode spectral model using interpolation polynomials (TASMIP) codes were used for simulation studies and digital radiography, and human chest phantoms were used for experimental studies. The results of the simulation study showed improved image contrast-to-noise ratio (CNR) and coefficient of variation (COV) values and bone thickness estimation accuracy by applying the ACNR and SSH methods. Furthermore, the chest phantom images showed better image quality with the SSH and ACNR methods compared to the SLS method. In particular, the bone texture characteristics were well-described by applying the SSH and ACNR methods. In conclusion, the SSH and ACNR methods improved the accuracy of material quantification and image quality in dual-energy radiography compared to SLS. Our results can contribute to better diagnostic capabilities of dual-energy images and accurate material quantification in various clinical situations.

Insufficient accuracy of the ultrasound-based determination of Achilles tendon cross-sectional area

The accurate assessment of the Achilles tendon cross-sectional area (CSA) is a crucial prerequisite to investigate tendon adaptation and to calculate the tendon Young׳s modulus. Besides magnetic resonance imaging (MRI), ultrasonography emerged as an alternative imaging technique. The purpose of the present study was to assess the objectivity and reliability of the ultrasound-based methodology and its validity with respect to the established MRI-based assessment.The Achilles tendon CSA from 17 healthy males was assessed by ultrasonography at the proximal, medial and distal position five times each on two separate days and three observers segmented the CSAs. For the validation, MRI-based CSA measurements were provided accordingly.The analysis of the ultrasound-based method revealed significant observer and day effects (p<0.05), despite high intra-class correlation coefficients for the three observers (>0.93) and both days (>0.89), respectively. The mean typical percentage error of both days was 7.1%. Comparing both methods, ultrasonography underestimated (19%) the CSA values obtained by MRI (p<0.05). Although the correlation coefficients of both methods were high in all three positions (>0.88), the respective absolute difference of in average 12mm2 and limits of agreement of up to +28mm2 and −2mm2 (~37% of the mean CSA) evidence considerable inconsistency.Besides the dependency of the CSA determination from the observer, the ultrasound method is not sensitive enough to detect physiological changes in tendon morphology of the magnitude that is reported by intervention studies. Furthermore, the validity analysis revealed a lack of agreement between both methods. Therefore, the ultrasound-based methodology cannot be recommended for an accurate Achilles tendon CSA determination in vivo.

Performance improvement and patient safety program-guided quality improvement initiatives can significantly reduce computed tomography imaging in pediatric trauma patients.

Morbidity and mortality of cervical spine (C-spine) injury in pediatric trauma patients are high, necessitating quick and accurate diagnosis. Best practices emphasize minimizing radiation exposure through decreased reliance on computed tomography (CT), instead using clinical assessment, physical examination, and alternate imaging techniques. We implemented an institutional performance improvement and patient safety (PIPS) program initiative for C-spine clearance in 2010 because of high rates of CT scans among pediatric trauma patients. A retrospective review of pediatric trauma patients, aged 0 years to 14 years, in the pre- and post-PIPS implementation periods was conducted. Rates of C-spine CT, overall CT, other imaging modalities, radiation exposure, patient characteristics, and injury severity were compared, and compliance with PIPS protocol was reviewed. Patient characteristics and injury severity were similar before and after PIPS implementation. C-spine CT rates decreased significantly between groups (30% vs. 13%, p < 0.001), whereas C-spine plain x-ray rates increased significantly (7% vs. 25%, p < 0.001). There was no difference in C-spine magnetic resonance imaging between groups (12% vs. 10%, p = 0.11). In 2007, 71% of patients received a CT scan for any reason. However, the overall CT rate decreased significantly between groups (60% vs. 45%, p < 0.001). There was an estimated 22% decrease in lifetime attributable risk (LAR) for any cancer due to ionizing imaging exposure in males and 38% decrease in females between the pre- and post-PIPS groups. There was a 54% decrease in LAR for thyroid cancer in males and females between groups; 2014 compliance with the protocol was excellent (82-90% per quarter). Performance improvement and patient safety program-generated protocol can significantly decrease ionizing radiation exposure. We demonstrate that a simple protocol focused on C-spine imaging has high compliance, decreased C-spine CT scans, and decreased LAR for thyroid cancer. A secondary benefit is a reduction in total CT imaging, with an associated decrease in LAR for all cancers. Therapeutic study, level IV; diagnostic study, level III.

Potential of Hyperspectral Imaging for Label‐free Tissue and Pathology Classification

The ultimate goal of this project is to develop a novel imaging system that allows classification of both normal and pathogenic tissues based on fluorescence excitation spectra. Current imaging diagnostic techniques have limited capacity to classify normal tissue or detect pathogenic states. In vivo imaging suffers from poor signal to noise ratios and excessive data acquisition times while most alternative imaging techniques offer little molecular specificity. Our previous research has shown that excitation scanning hyperspectral imaging produces image data with high signal to noise ratios, fast acquisition times, and the potential to determine molecular composition. Here, we present data comparing characteristic spectral signatures for a range of tissue types. These data serve as a basis for establishing normal tissue spectra and characterizing molecular composition per tissue type. Tissues from Sprague Dawley rats were collected as 2 cm cubes and stored in cold PBS. Immediately following harvest, a custom inverted microscope (TE‐2000, Nikon Instruments) with a Xe arc lamp and an array of thin film tunable filters (VersaChrone, Semrock, Inc.) were used to collect hyperspectral image data from each sample. Scans utilized excitation wavelengths from 360nm to 600nm in 5nm increments. Three fields of view were recorded for each sample. Hyperspectral images were analyzed with custom Matlab scripts including linear spectral unmixing (LSU), principal component analysis (PCA), and Gaussian mixture modeling (GMM). Spectra were examined for potential characteristic features such as unique intensity peaks at specific wavelengths or ratios between intensity peaks. The resultant spectra vary among tissues types, which alludes to a unique spectral signature per tissue type. Additionally, excitation spectra appear to be a mixture of pure endmembers with commonalities in multiple tissue types, potentially identifiable through GMM. These results suggest that most tissues have common molecules and that intensity ratios of these molecules may serve as a signature for characterizing tissue composition. In addition, variations in signatures could indicate a change in molecular composition coincident with changes in pathology. Thus, excitation scanning hyperspectral imaging may be a potential diagnostic tool with the ability to distinguish tissues of varying pathology.Support or Funding InformationThis work is supported by P01HL066299 and the Abraham Mitchell Cancer Research Fund.

Imaging patients with renal impairment.

Imaging with intravascular contrast media is generally considered safe, particularly in patients without renal failure. However, as renal function deteriorates, the potential risk of nonallergic-type adverse events increases. This presents a unique challenge, particularly when the use of intravenous contrast media is deemed essential for diagnostic purposes. Following a discussion regarding the definition and epidemiology of kidney injury, this review focuses on the evolving understanding of both contrast-induced nephropathy and nephrogenic systemic fibrosis and discusses preventative strategies aimed at minimizing the risk of developing these entities. Alternative non-contrast imaging techniques are also discussed.