The obese emergency patient: imaging challenges and solutions

The impact of X-ray scatter correction software on abdomen radiography in terms of image quality and radiation dose

INTRODUCTION

The conventional anti-scatter grid is widely used in X-ray radiography to reduce scattered X-rays, but it increases patient dose. Scatter-correction software offers a dose-reducing alternative by correcting for scattered X-rays without a physical grid. Grids and software correction are necessary to reduce scatter radiation and improve image quality especially for the large body parts. The scatter correction can be beneficial in situations where the use of grid is challenging. The implementation of grids and advanced software correction techniques is imperative to ensure that radiographic images maintain high levels of clarity, contrast, and resolution, and ultimately facilitating more accurate diagnoses. This study compares image quality and radiation dose for abdomen exams using scatter correction software and physical grids.

METHODS

An anthropomorphic phantom (abdomen) underwent imaging with varying fat and lean tissue layers and body mass index (BMI) configurations. Imaging parameters included 70 kVp tube voltage, 110 cm SID, and Automatic Exposure Control (AEC) both lateral and central chambers. AP abdomen X-ray projections were acquired with and without an anti-scatter grid, and scatter correction software was applied. Image quality was assessed using contrast to noise ratio (CNR) and signal to noise ratio (SNR) metrics. The tube current mAs was considered an exposure factor that affected radiation dose and was used to compare the VG software and physical grid. Radiation dose was measured using Dose Area Products (DAP). The effective dose was estimated using Monte Carlo simulation-PCXMC software. Paired t-tests were used to investigate the image quality difference between the Gridless and VG software, Gridless and PG, and VG software and PG approaches. For the DAP and effective dose, paired t-test was used to investigate the difference between VG software and PG.

RESULTS

Images acquired with a grid had the highest mean CNR (71.3 ± 32) compared to Gridless (50 ± 33.8) and scatter correction software (59.3 ± 37.9). The mean SNR of the grid images was (82.7.3 ± 38.9), which is 18% higher than the scatter correction software images (70.4 ± 36.7) and 29% higher than in the Gridless images (62.9.3 ± 34). The mean DAP value was reduced by 81% when the scatter correction software was used compared to the grid (mean: 65.4 μGy.m2 and 338.2 μGy.m2, respectively) with a significant difference (p = 0.001). Scatter correction software resulted in a lower effective dose compared to physical grid use, (mean difference± SD = -0.3 ± 0.18 mSv) with a significant difference (P = 0.02).

CONCLUSION

Scatter correction software reduced the radiation dose required but images employing a grid yielded higher CNR and SNR. However, the radiation dose reduction might affect the image quality to a level that impacts the diagnostic information available. Thus, further research needs to be conducted to optimise the use of the scatter correction software.

IMPLICATION FOR PRACTICE

Objectively, X-ray scatter correction software might be promising in conditions where a grid cannot be applied.

Influence of spectral shaping and tube voltage modulation in ultralow-dose computed tomography of the abdomen

PURPOSE

Unenhanced abdominal CT constitutes the diagnostic standard of care in suspected urolithiasis. Aiming to identify potential for radiation dose reduction in this frequent imaging task, this experimental study compares the effect of spectral shaping and tube voltage modulation on image quality.

METHODS

Using a third-generation dual-source CT, eight cadaveric specimens were scanned with varying tube voltage settings with and without tin filter application (Sn 150, Sn 100, 120, 100, and 80 kVp) at three dose levels (3 mGy: standard; 1 mGy: low; 0.5 mGy: ultralow). Image quality was assessed quantitatively by calculation of signal-to-noise ratios (SNR) for various tissues (spleen, kidney, trabecular bone, fat) and subjectively by three independent radiologists based on a seven-point rating scale (7 = excellent; 1 = very poor).

RESULTS

Irrespective of dose level, Sn 100 kVp resulted in the highest SNR of all tube voltage settings. In direct comparison to Sn 150 kVp, superior SNR was ascertained for spleen (p ≤ 0.004) and kidney tissue (p ≤ 0.009). In ultralow-dose scans, subjective image quality of Sn 100 kVp (median score 3; interquartile range 3-3) was higher compared with conventional imaging at 120 kVp (2; 2-2), 100 kVp (1; 1-2), and 80 kVp (1; 1-1) (all p < 0.001). Indicated by an intraclass correlation coefficient of 0.945 (95% confidence interval: 0.927-0.960), interrater reliability was excellent.

CONCLUSIONS

In abdominal CT with maximised dose reduction, tin prefiltration at 100 kVp allows for superior image quality over Sn 150 kVp and conventional imaging without spectral shaping.

Generation of tissues outside the field of view (FOV) of radiation therapy simulation imaging based on machine learning and patient body outline (PBO)

BACKGROUND

It is not unusual to see some parts of tissues are excluded in the field of view of CT simulation images. A typical mitigation is to avoid beams entering the missing body parts at the cost of sub-optimal planning.

METHODS

This study is to solve the problem by developing 3 methods, (1) deep learning (DL) mechanism for missing tissue generation, (2) using patient body outline (PBO) based on surface imaging, and (3) hybrid method combining DL and PBO. The DL model was built upon a Globally and Locally Consistent Image Completion to learn features by Convolutional Neural Networks-based inpainting, based on Generative Adversarial Network. The database used comprised 10,005 CT training slices of 322 lung cancer patients and 166 CT evaluation test slices of 15 patients. CT images were from the publicly available database of the Cancer Imaging Archive. Since existing data were used PBOs were acquired from the CT images. For evaluation, Structural Similarity Index Metric (SSIM), Root Mean Square Error (RMSE) and Peak signal-to-noise ratio (PSNR) were evaluated. For dosimetric validation, dynamic conformal arc plans were made with the ground truth images and images generated by the proposed method. Gamma analysis was conducted at relatively strict criteria of 1%/1 mm (dose difference/distance to agreement) and 2%/2 mm under three dose thresholds of 1%, 10% and 50% of the maximum dose in the plans made on the ground truth image sets.

RESULTS

The average SSIM in generation part only was 0.06 at epoch 100 but reached 0.86 at epoch 1500. Accordingly, the average SSIM in the whole image also improved from 0.86 to 0.97. At epoch 1500, the average values of RMSE and PSNR in the whole image were 7.4 and 30.9, respectively. Gamma analysis showed excellent agreement with the hybrid method (equal to or higher than 96.6% of the mean of pass rates for all scenarios).

CONCLUSIONS

It was first demonstrated that missing tissues in simulation imaging could be generated with high similarity, and dosimetric limitation could be overcome. The benefit of this study can be significantly enlarged when MR-only simulation is considered.

Obesity bias in diagnostic radiography students: A survey of attitudes, perceptions and technical confidence

INTRODUCTION

Obesity bias exists in healthcare professionals and students from numerous disciplines and negatively impacts the quality of care, outcomes, engagement, and satisfaction of their patients. With obesity rates continuing to rise in the United Kingdom (UK), more patients will be affected than ever, and it is becoming an increasingly important issue to tackle. This study aims to assess the attitudes to obesity of student diagnostic radiographers and determine if obesity bias exists in this population.

METHOD

Student radiographers (n = 140) at a single university in the UK were invited to complete an online survey comprising measures designed to assess levels of bias and attitudes towards obesity, including the Attitude Towards Obese Persons (ATOP) scale. Likert-type scales were used to collect quantitative data, and data analysis included descriptive statistics, frequencies, and Spearman's rank correlation coefficient.

RESULTS

Responses were received from n = 38 students. The mean ATOP score for participants was 70.37 (SD = 19.26). With 26 % (n = 10) scoring below 60, demonstrating strong negative attitudes towards obese individuals. Additionally, students (76.3 %; n = 29) indicated that they observed high levels of obesity bias whilst on clinical placement. There was a statistically significant correlation between levels of weight bias and students' confidence in working with obese patients (r(36) = 0.4, p 0.01). Students who are less confident working with obese patients had higher levels of obesity bias.

CONCLUSIONS

Obesity bias exists in radiography students at levels comparable to those that have been found previously in other healthcare professionals and students. Furthermore, radiography students lacked confidence in their technical ability to work with obese patients and lower confidence levels were associated with higher levels of obesity bias.

IMPLICATIONS FOR PRACTICE

The findings of this study provide preliminary knowledge upon which future research can be built.

Evaluation of the impact of a novel denoising algorithm on image quality in dual-energy abdominal CT of obese patients

OBJECTIVES

Evaluate a novel algorithm for noise reduction in obese patients using dual-source dual-energy (DE) CT imaging.

METHODS

Seventy-nine patients with contrast-enhanced abdominal imaging (54 women; age: 58 ± 14 years; BMI: 39 ± 5 kg/m2, range: 35-62 kg/m2) from seven DECT (SOMATOM Flash or Force) were retrospectively included (01/2019-12/2020). Image domain data were reconstructed with the standard clinical algorithm (ADMIRE/SAFIRE 2), and denoised with a comparison (ME-NLM) and a test algorithm (rank-sparse kernel regression). Contrast-to-noise ratio (CNR) was calculated. Four blinded readers evaluated the same original and denoised images (0 (worst)-100 (best)) in randomized order for perceived image noise, quality, and their comfort making a diagnosis from a table of 80 options. Comparisons between algorithms were performed using paired t-tests and mixed-effects linear modeling.

RESULTS

Average CNR was 5.0 ± 1.9 (original), 31.1 ± 10.3 (comparison; p < 0.001), and 8.9 ± 2.9 (test; p < 0.001). Readers were in good to moderate agreement over perceived image noise (ICC: 0.83), image quality (ICC: 0.71), and diagnostic comfort (ICC: 0.6). Diagnostic accuracy was low across algorithms (accuracy: 66, 63, and 67% (original, comparison, test)). The noise received a mean score of 54, 84, and 66 (p < 0.05); image quality 59, 61, and 65; and the diagnostic comfort 63, 68, and 68, respectively. Quality and comfort scores were not statistically significantly different between algorithms.

CONCLUSIONS

The test algorithm produces quantitatively higher image quality than current standard and existing denoising algorithms in obese patients imaged with DECT and readers show a preference for it.

CLINICAL RELEVANCE STATEMENT

Accurate diagnosis on CT imaging of obese patients is challenging and denoising algorithms can increase the diagnostic comfort and quantitative image quality. This could lead to better clinical reads.

KEY POINTS

• Improving image quality in DECT imaging of obese patients is important for accurate and confident clinical reads, which may be aided by novel denoising algorithms using image domain data. • Accurate diagnosis on CT imaging of obese patients is especially challenging and denoising algorithms can increase quantitative and qualitative image quality. • Image domain algorithms can generalize well and can be implemented at other institutions.

Erect pelvic radiography with fat tissue displacement: Impact on radiation dose and image quality

INTRODUCTION

Pelvic radiography is one of the most frequent general radiography imaging procedures. Pelvic radiography is usually performed in the supine position, but in some cases erect imaging is performed. The aim of this study was to determine whether radiation dose and image quality differ between two different erect pelvic radiographic procedures in overweight and obese patients, with and without displacement of anterior adipose tissue.

METHODS

This research was a two-part study. The first part of the study was to determine a suitable fat displacement band that would not produce artifacts on the resulting radiograph when fat tissue was displaced. The second part of the study was performed in a clinical setting on 60 overweight or obese patients (BMI ≥25) referred for erect pelvic imaging. Patients were randomly divided into two equal groups, half of which displaced adipose tissue from the region of interest and the other group did not. Waist and hip circumference, height, weight, dose-area- product (DAP), primary field size, source-to-skin distance, mAs, and kV were measured. Body Mass Index (BMI), entrance surface dose (ESD), and effective dose (ED) were then calculated. The resulting images were evaluated by three radiologists.

RESULTS

It was found that a thin cotton triangular bandage produced no visible radiographic artefacts. In the group of patients using the fat displacement protocol, a statistically significant reduction in waist circumference (4.7%), DAP (38.5%), ESD (44%) and ED (38.7%) were observed (p < 0.05). In addition, a significant (p < 0.05) increase was found for all the observed image quality criteria and overall total image score with exception of sacroiliac joint, iliac crest and pubic/ischial rami.

CONCLUSION

Based on the results, the use of the adipose tissue displacement protocol for radiography of the pelvis and hip in the erect position in overweight and obese patients is recommended.

IMPLICATIONS FOR PRACTICE

The use of cotton bands to remove adipose tissue during pelvic imaging in obese and overweight patients results in a reduction of radiation dose received by the patient and improves image quality. This technique is quick, easy, and inexpensive.

An evaluation of radiation therapy patient body mass index trends and potential impact on departmental resource planning

INTRODUCTION

Radiation therapy (RT) offers a less invasive management option for bariatric cancer patients. As the proportion of Australians categorised overweight or obese approaches 70%, it is not well understood how this growth will impact RT departments. The aim of this study was to evaluate the current and potential future body mass index (BMI) of RT patients at one centre, with the purpose of identifying variables that may impact resource planning decisions.

METHODS

De-identified demographic data including gender, age, diagnosis code, activity code and BMI were obtained from MOSAIQ® oncology information system for 5548 courses of RT commenced between 2017 and 2020, and retrospectively analysed. Descriptive statistics were used to summarise the data. Simple and multiple linear regression was used to analyse for statistically significant relationships between variables.

RESULTS

Of all patient courses, 64% were overweight or obese. Average BMI increased over time by 0.3 kg/m² per year. Courses related to the young and elderly had a lower average BMI. Breast, brain/skull, and pelvis/prostate treatment sites had a significant association with a higher average BMI. Thorax treatment sites had a lower average BMI, but this average is increasing at the fastest rate of all treatment sites. Prone breast courses had an average BMI 5.58 kg/m² higher than IMRT/VMAT courses.

CONCLUSION

Results demonstrate that patient BMI is increasing. Resources related to breast courses (breast board, prone board) and thorax courses (lung board) may experience increased strain in the future. Modifications to department workflow and scheduling are likely required. Further research into staffing implications is recommended.

The reliability of video fluoroscopy, ultrasound imaging, magnetic resonance imaging and radiography for measurements of lumbar spine segmental range of motion in-vivo: A review

BACKGROUND

Lower back pain (LBP) is a principal cause of disability worldwide and is associated with a variety of spinal conditions. Individuals presenting with LBP may display changes in spinal motion. Despite this, the ability to measure lumbar segmental range of motion (ROM) non-invasively remains a challenge.

OBJECTIVE

To review the reliability of four non-invasive modalities: Video Fluoroscopy (VF), Ultrasound imaging (US), Magnetic Resonance Imaging (MRI) and Radiography used for measuring segmental ROM in the lumbar spine in-vivo.

METHODS

The methodological quality of seventeen eligible studies, identified through a systematic literature search, were appraised.

RESULTS

The intra-rater reliability for VF is excellent in recumbent and upright positions but errors are larger for intra-rater repeated movements and inter-rater reliability shows larger variation. Excellent results for intra- and inter-rater reliability are seen in US studies and there is good reliability within- and between-day. There is a large degree of heterogeneity in MRI and radiography methodologies but reliable results are seen.

CONCLUSIONS

Excellent reliability is seen across all modalities. However, VF and radiography are limited by radiation exposure and MRI is expensive. US offers a non-invasive, risk free method but further research must determine whether it yields truly consistent measurements.

Modification of [18F]-FDG PET/CT imaging protocols in obese oncology patients: A nationwide survey

INTRODUCTION

The use of medical imaging for diagnosis, staging and follow-up in Oncology context is incredibly important, being the use of [18F]-FDG PET/CT particularly advantageous in specific contexts like the case of obese patients. However, imaging the latter can be challenging sometimes, since their own body size may affect overall image quality and adds technical difficulties for the operator(s) performing the examination.

METHODS

This research project was developed with the aim of analysing the current personal practices of Portuguese Nuclear Medicine Technologists (NMTs) in the adaptation of ¹⁸F-FDG PET/CT oncological protocols for obese patients and comparing the results with parameters referenced in literature. A non-experimental research study was conducted using a survey delivered online to NMTs through social media platforms (Facebook® and LinkedIn®) and by sending the link directly to contacts within the research team professional and personal networks.

RESULTS

Answers from a total of 26 participants were obtained, with 88.5% of participants admitting modifying technical protocols in examinations for obese patients. Changes in PET protocols included an increase in the administered activity (60.9%), an increase in scan time per individual bed position (69.6%) and the use of Time-of-Flight (TOF) technology whenever available. Protocol changes in CT included increasing the mA (82.6%), raising the KVp (47.8%), the application of iterative reconstruction (69.6%) and the use of automatic exposure control (AEC) (52.2%). The remaining parameters (pitch, algorithm, slice thickness, display FOV, gantry rotation time and energy acceptance window) were claimed not to be modified by around 90% of professionals.

CONCLUSION

Portuguese NMTs tend to change the [18F]-FDG PET/CT protocols for obese patients. However, while some of the parameters appear to be contradictory or redundant, others require further optimisation, especially in the CT component.

IMPLICATIONS FOR PRACTICE

Efforts should be made to optimize acquisition protocols used in [18F]-FDG PET/CT scans for obese patients.

Improving plane wave ultrasound imaging through real-time beamformation across multiple arrays

Ultrasound imaging is a widely used diagnostic tool but has limitations in the imaging of deep lesions or obese patients where the large depth to aperture size ratio (f-number) reduces image quality. Reducing the f-number can improve image quality, and in this work, we combined three commercial arrays to create a large imaging aperture of 100 mm and 384 elements. To maintain the frame rate given the large number of elements, plane wave imaging was implemented with all three arrays transmitting a coherent wavefront. On wire targets at a depth of 100 mm, the lateral resolution is significantly improved; the lateral resolution was 1.27 mm with one array (1/3 of the aperture) and 0.37 mm with the full aperture. After creating virtual receiving elements to fill the inter-array gaps, an autoregressive filter reduced the grating lobes originating from the inter-array gaps by − 5.2 dB. On a calibrated commercial phantom, the extended field-of-view and improved spatial resolution were verified. The large aperture facilitates aberration correction using a singular value decomposition-based beamformer. Finally, after approval of the Stanford Institutional Review Board, the three-array configuration was applied in imaging the liver of a volunteer, validating the potential for enhanced resolution.

Percutaneous CT-guided superior mesenteric vein access for portal vein recanalization-transjugular intrahepatic portosystemic shunt

Portal vein recanalization-transjugular intrahepatic portosystemic shunt (PVR-TIPS) is a valuable technique in the treatment cirrhosis and portal vein (PV) thrombosis. Only a few studies have reported cases of utilizing the transmesenteric approach in the procedure's initial portal access. Here, we report the successful utilization of a CT-guided percutaneous puncture of the superior mesenteric vein (SMV) for PVR-TIPS in a patient with splenic vein thrombosis. A 54-year-old male with a history of morbid obesity (BMI: 44.67), hepatitis C, NASH cirrhosis, esophageal varices, and complete PV thrombosis presented for PVR-TIPS. An initial percutaneous transplenic approach was attempted, but was aborted due to the discovery of a splenic vein thrombosis. Subsequently, the patient was brought back into the hybrid-angio CT suite, and the SMV was accessed percutaneously with a 21-gauge needle under 4D CT-guidance. A 5-Fr micropuncture sheath was then placed. Additional portal venogram confirmed PV thrombosis. Right internal jugular vein (IJV) access was then obtained, and the right hepatic vein was catheterized. A loop snare was advanced from the SMV access into the right PV. A Colapinto needle was later positioned in the right hepatic vein, and the right PV was accessed using the loop snare as a target. A wire was then advanced and captured by the snare, and brought down through the PV. The tract was dilated with a 10 mm balloon, and a Viatorr stent was deployed. Balloon embolectomy of the SMV, splenomesenteric vein, and TIPS were then performed with a CODA balloon with improvement in flow through the TIPS on final portal venogram. Portosystemic gradient was 11 mmHg initially and 10 mmHg post-TIPS. Follow-up TIPS venogram in 3 weeks showed a widely patent TIPS. CT-guided percutaneous SMV access may serve as valuable technique in PVR-TIPS when traditional modes of initial portal access for recanalization are unobtainable.

Ultrasound-guided renal access and balloon dilation for PCNL in the prone position: results of a multicenter prospective observational study

PURPOSE

To investigate the safety and efficacy of ultrasound-guided renal access and tract dilation using balloon dilators, as well as to identify suitable patients for this technique.

METHODS

Consecutive patients undergoing ultrasound-guided PCNL using balloon dilators between December 2019 and June 2020 in seven large medical centers from China were prospectively enrolled. Demographic and perioperative parameters of the patients were collected. Logistic regression analysis was used to analyze factors that would affect the success rate of tract establishment using ultrasound-guided renal access and balloon dilation.

RESULTS

A total of 170 patients were included in this study, among whom, 91.18% of the (155/170) patients had a successful tract establishment under ultrasound guidance on the first attempt. The stone-free rate was 83.5% and postoperative complications occurred in 14 patients (8.23%). In univariate analysis, history of ipsilateral surgery (p = 0.026), and stone diameter (p = 0.01) were significantly associated with tract establishment failure, while a larger width of the target calyx (p = 0.016) and the presence of hydronephrosis (p = 0.001) were significantly associated with a successful tract establishment. In multivariate analysis, only hydronephrosis in target calyx (p = 0.027) was a favorable factor for successful tract establishment, and the history of ipsilateral renal surgery (p = 0.012) was the only independent risk factor for failure of tract establishment.

CONCLUSION

It was safe and effective to establish percutaneous renal access with balloon dilation under whole-process ultrasound monitoring during PCNL. Furthermore, patients with a hydronephrotic target calyx and without history of ipsilateral renal surgery were most suited to this technique. Trial registration CHiCTR1800014448.

Metal artefact reduction in low-dose computed tomography: Benefits of tin prefiltration versus postprocessing of dual-energy datasets over conventional CT imaging

INTRODUCTION

The purpose of this study was to determine the potential for metal artefact reduction in low-dose multidetector CT as these pose a frequent challenge in clinical routine. Investigations focused on whether spectral shaping via tin prefiltration, virtual monoenergetic imaging or virtual blend imaging (VBI) offers superior image quality in comparison with conventional CT imaging.

METHODS

Using a third-generation dual-source CT scanner, two cadaveric specimens with different metal implants (dental, cervical spine, hip, knee) were examined with acquisition protocols matched for radiation dose with regards to tube voltage and current. In order to allow for precise comparison, and due to the relatively short scan lengths, automatic tube current modulation was disabled. Specifically, the following scan protocals were examined: conventional CT protocols (100/120 kVp), tin prefiltration (Sn 100/Sn 150 kVp), VBI and virtual monoenergetic imaging (VME 100/120/150 keV). Mean attenuation and image noise were measured in hyperdense and hypodense artefacts, in artefact-impaired and artefact-free soft tissue. Subjective image quality was rated independently by three radiologists.

RESULTS

Objectively, Sn 150 kVp allowed for the best reduction of hyperdense streak artefacts (p < 0.001), while VME 150 keV and Sn 150 kVp protocols facilitated equally good reduction of hypodense artefacts (p = 0.173). Artefact-impaired soft tissue attenuation was lowest in Sn 150 kVp protocols (p ≤ 0.011), whereas all VME showed significantly less image noise compared to conventional or tin-filtered protocols (p ≤ 0.001). Subjective assessment favoured Sn 150 kVp regarding hyperdense streak artefacts and delineation of cortical bone (p ≤ 0.005). The intraclass correlation coefficient was 0.776 (95% confidence interval: 0.712-0.831; p < 0.001) indicating good interrater reliability.

CONCLUSION

In the presence of metal implants in our cadaveric study, tin prefiltration with 150 kVp offers superior artefact reduction for low-dose CT imaging of osseous tissue compared with virtual monoenergetic images of dual-energy datasets. The delineation of cortical boundaries seems to benefit particularly from spectral shaping.

IMPLICATIONS FOR PRACTICE

Low-dose CT imaging of osseous tissue in combination with tin prefiltration allows for superior metal artefact reduction when compared to virtual monoenergetic images of dual-energy datasets. Employing this technique ought to be considered in daily routine when metal implants are present within the scan volume as findings suggest it allows for radiation dose reduction and facilitates diagnosis relevant to further treatment.

Outcomes in Obese vs Non-Obese Injured Patients at a Level 1 Trauma Center and Bariatric Surgery Center of Excellence

BACKGROUND

We hypothesized that the outcomes of trauma patients with a body mass index (BMI) equal to or greater than 30 compared to patients with BMI less than 30 would not differ at a level 1 trauma center that is also a Metabolic and Bariatric Surgery Center of Excellence in the Metabolic and Bariatric Surgery Accreditation Quality Improvement Program (MBSAQIP).

STUDY DESIGN

Patients equal to and greater than 18 years old treated between 1/1/2018 and 12/31/2020 were included. Demographics, BMI, comorbidities, and outcomes (hospital-LOS, ICU-LOS, blood products used, and mortality) were compared between 2 groups: obese (BMI ≥30) vs non-obese (BMI <30).

RESULTS

Of the 4192 patients identified, 3821 met the inclusion criteria; 3019 patients had a BMI <30, and 802 had a BMI ≥30. There was a statistically significant difference between the 2 groups with respect to gender (females: 57% vs 47%, P < .0001) and age (median: 80 [IQR: 63-88] vs 69 [IQR: 55-81], P < .0001). When adjusted for age, sex, DM, dementia, ISS, and ICU admission, there was no statistically significant difference in hospital-LOS (4.30 [95% CI: 4.10, 4.52] vs 4.48 [95% CI: 4.18, 4.79]) or mortality. No statistical differences were seen between the 2 groups in blood product use.

CONCLUSIONS

Obesity did not correlate with poorer outcomes at an ACS-verified level 1 Trauma Center and Bariatric Surgery Center of Excellence. Further studies are needed to determine whether outcomes vary at hospitals without both designations.

Effect of Body Mass Index in Coronary CT Angiography Performed on a 256-Slice Multi-Detector CT Scanner

We aimed to investigate the effect of a patient’s body mass index (BMI) on radiation dose and image quality in prospectively ECG-triggered coronary CT angiography (CCTA) performed on a 256-slice multi-detector CT scanner. In total, 87 consecutive patients receiving CCTA examinations acquired with tube current modulation (TCM) and iterative reconstruction (IR) were enrolled in this study. The dose report recorded from the CT scanner console was used to derive the effective dose for patients. Subjective image quality scoring and objective noise measurements were conducted to quantify the impact of BMI on the image quality of CCTA. Because of the TCM technique, we expected tube current and radiation dose to increase as BMI increased. However, using TCM did not always guarantee sufficient radiation exposure to achieve consistent image quality for overweight or obese patients since the maximum X-ray tube output in milliamperes and kilovoltage peak was reached. The impact of photon starvation noise on image quality was not significant until BMI ≥ 27 kg/m2; this result could be due to IR’s noise reduction capability. Our results also suggest that using TCM with a noise index of 25 HU can reduce radiation dose without compromising image quality compared to images obtained based on the manufacturer’s default settings.

Concepts in Musculoskeletal Bone and Soft Tissue Biopsy

Imaging-guided needle biopsy of musculoskeletal lesions is a high-yield and low-risk procedure that can be used for definitive characterization of indeterminate bone and soft tissue lesions. Familiarity with the preprocedural, technical, and postprocedural steps is vital for the appropriate management of these cases. Biopsy request triage requires an awareness of definitively benign conditions and other tumor mimics. A complete clinical, laboratory, and imaging work-up is essential for procedural planning and determining pathologic concordance. Consultation with an orthopaedic oncologist is a requisite step to ensure maximizing biopsy yield and to avoid interference with any future limb-sparing surgical intervention. Knowledge of the equipment, pertinent medications, and appropriate biopsy technique can minimize the risk of periprocedural complications. Finally, the radiologist may be required to discuss the concordance of histopathology with preprocedure imaging, perform repeat image-guided biopsy, and carefully interpret sarcoma surveillance imaging examinations.

Ultrasound Image Optimization for the Interventional Radiologist

Understanding the basics and nuances of the functionality of ultrasound (US) equipment and of its various knobs and modes will enable the interventional radiologist to acquire higher quality US images. This, in turn will potentially allow US-guided procedures to be performed safely, and with greater operator confidence, and may also allow certain procedures to be performed with US instead of CT or fluoroscopic guidance. In this article, we review the practical aspects of US image optimization for the interventional radiologist, including equipment and transducer selection, depth, focal zone and gain setting adjustment, as well as special considerations for imaging the obese patient. Color Doppler image optimization and recent developments in ultrasound imaging are briefly discussed.

Infrastructure Design: A Critical Element in the Care of the Patient With Obesity

ABSTRACT

The worldwide rate of obesity continues to rise, causing healthcare systems to morph to meet the demands posed by the concomitant increase in comorbidities associated with this condition. Increasing patient weight imposes its own constraints on the safety of patients and providers; therefore, a sound healthcare facility infrastructure is required to properly address the medical needs of patients with obesity. Currently, most healthcare systems-in their attitudes, equipment, and facility design-are ill equipped to meet the needs of this epidemic. In this article, we discuss the facilities and equipment design considerations in providing medical care to patients with obesity. Extending beyond the physical plant, we also touch on organizational elements that enable the healthcare provider to safely care for this challenging patient population. The rising prevalence and disease burden of excess adiposity highlight the obligation to recognize that the design needs common to all of our patients must include the particular needs of the patient with obesity.

An Approach to Standard Perioperative Transthoracic Echocardiography Practice for Anesthesiologists-Perioperative Transthoracic Echocardiography Protocols

The use of intraoperative transesophageal echocardiography (TEE) has become the standard of care for most cardiac surgical procedures. There are guidelines established for training, practice, and quality improvement in perioperative TEE by the joint efforts of the American Society of Echocardiography and Society of Cardiovascular Anesthesiologists. Cardiac point-of-care ultrasound (POCUS) increasingly is being incorporated into anesthesiologists' training and practice. While a special "certification in Critical Care Echocardiography" was created by the National Board of Echocardiography in 2019, there currently exist no guidelines for training, certification, and practice of perioperative TTE by anesthesiologists. In this review, the authors describe the categories, indications and applications of perioperative TTE and provide a recommended sequence for performing an examination tailored to the evaluation of perioperative patients. Although the authors describe a protocol utilized at their institution, there are no standards described in the literature for PTTE. Cardiac anesthesiologists and cardiac anesthesia societies (Society of Cardiovascular Anesthesiologists, European Association of Cardiothoracic Anesthesiologists) must come forward to establish standards working in collaboration with echocardiography societies (American Society of Echocardiography, European Society of Cardiology).

Understanding radiographic decision-making when imaging obese patients: A Think-Aloud study

Introduction

The incidence of obesity has been steadily rising over the last few decades and is having a significant impact upon the health system. In radiography, a particular challenge of imaging obese patients is implementing the as low as reasonably achievable (ALARA) principle when determining radiation dose, and technical and patient‐care adaptations. This study aimed to better understand the decision‐making strategies of experienced radiographers in determining imaging and exposure factor selection in the context of imaging obese patients.

Methods

This study employed a ‘think‐aloud,’ methodology, and eight experienced diagnostic radiographers working in clinical education were recruited to perform routine AP abdominal X‐ray projections on an anthropomorphic phantom. They were asked to simultaneously verbalise emerging thoughts as they considered positioning, exposure selection and image evaluation. This process was repeated with three different phantom sizes, each representing an increased BMI from ‘healthy,’ to, ‘morbidly obese.’ Audio recordings were transcribed and interpreted via Bowman’s (1997) theory of radiographic judgement and decision‐making.

Results

Analysis of interview transcripts identified 12 key concepts considered by experienced radiographers. Differences in radiographic concepts were considered when imaging phantoms of different sizes was demonstrated. A shift from segmental (e.g. positioning) to more environmental factors (e.g. patient comfort) and an increase in the number of verbal considerations with increasing phantom size were identified. The shift in focus of decision‐making stages identified the greater need to consider contextual factors such as patient comfort and repeatability when imaging obese patients.

Conclusion

Experienced radiographers find imaging obese patients challenging and alter their perception of image quality to accommodate for patient presentation. The findings will help inform future research, practice guidelines and learning resources to provide optimal imaging and care for obese patients, especially for student education.

Prediction of successful caudal epidural injection using color Doppler ultrasonography in the paramedian sagittal oblique view of the lumbosacral spine

Background

Ultrasound-guided caudal epidural injection (CEI) is limited in that it cannot confirm drug distribution at the target site without fluoroscopy. We hypothesized that visualization of solution flow through the inter-laminar space of the lumbosacral spine using color Doppler ultrasound alone would allow for confirmation of drug distribution. Therefore, we aimed to prospectively evaluate the usefulness of this method by comparing the color Doppler image in the paramedian sagittal oblique view of the lumbosacral spine (LS-PSOV) with the distribution of the contrast medium observed during fluoroscopy.

Methods

Sixty-five patients received a 10-mL CEI of solution containing contrast medium under ultrasound guidance. During injection, flow was observed in the LS-PSOV using color Doppler ultrasonography, following which it was confirmed using fluoroscopy. The presence of contrast image at L5-S1 on fluoroscopy was defined as “successful CEI.” We then calculated prediction accuracy for successful CEI using color Doppler ultrasonography in the LS-PSOV. We also investigated the correlation between the distribution levels measured via color Doppler and fluoroscopy.

Results

Prediction accuracy with color Doppler ultrasonography was 96.9%. The sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 100%, 100%, and 60.0%, respectively. In 52 of 65 patients (80%), the highest level at which contrast image was observed was the same for both color Doppler ultrasonography and fluoroscopy.

Conclusions

Our findings demonstrate that color Doppler ultrasonography in the LS-PSOV is a new method for determining whether a drug solution reaches the lumbosacral region (i.e., the main target level) without the need for fluoroscopy.

Pearls and Pitfalls for Soft-Tissue and Bone Biopsies: A Cross-Institutional Review

Management of soft-tissue and bone neoplasms depends on a definitive histologic diagnosis. Percutaneous image-guided biopsy of bone and soft-tissue tumors is a cost-effective and accurate method to obtain a histopathologic diagnosis. Biopsy requests must be approached thoughtfully to avoid numerous potential pitfalls. Hasty biopsy planning places the patient at increased risk for misdiagnosis, delayed therapy, repeated invasive procedures, and substantial morbidity. Biopsy planning begins with a thorough review of the relevant clinical history and pertinent imaging. The biopsy route must be planned in concert with the referring orthopedic oncologist to preserve limb-sparing options. Carefully selecting the most appropriate imaging modality to guide the biopsy increases the chances of reaching a definitive diagnosis. It is also critical to identify and target with expertise the part of the lesion that is most likely to yield an accurate diagnosis. Percutaneous biopsy is a safe procedure, and familiarity with preprocedural laboratory testing parameters, anticoagulation guidelines, and commonly used sedation medications minimizes the risk of complications while ensuring patient comfort. Nondiagnostic biopsy results are not infrequent and may still have value in guiding patient treatment. Awareness of the imaging manifestations of tumor recurrence is also important. The aim of this article is to provide a comprehensive review of pertinent preprocedural, periprocedural, and postprocedural considerations for bone and soft-tissue musculoskeletal biopsies.The online slide presentation from the RSNA Annual Meeting is available for this article.^©RSNA, 2020.

Can patient characteristics explain variance in ultrasound strain elastography measures of the quadratus femoris and patellar tendons?

OBJECTIVES

To explore the associations between participant characteristics and magnitudes of difference in paired elastography measures of knee tendon from different ultrasound systems, and to compare strain elastography pattern description.

MATERIALS AND METHODS

Quadriceps and patellar tendons of 20 healthy volunteers (40 tendons) were examined by an experienced operator employing two ultrasound systems (GE S8 and Esaote MyLab 70XVG). Pearson/Spearman correlations explored the influence of participant characteristics (BMI, body fat %, leg circumference, activity level) on the magnitude of differences between measures. Paired-sample t test or Wilcoxon signed rank test were performed to compare repeated measures of individual ultrasound systems.

RESULTS

The quadriceps tendon was characteristically stiffer than the patellar tendon. Participant characteristics were associated with within machine differences of the distal quadriceps tendon (BMI; r = 0.49, p = 0.028-0.03 and body fat %; r = 0.43, p = 0.05-0.056) ER measures.

CONCLUSIONS

Anthropometric and body composition parameters were associated with within machine differences for elasticity measures, where high BMI and body fat % contribute to paired measurement variance at the distal quadriceps tendon. Strain elastography protocols should be standardised, repeated ER measures performed using the same US system and patient characteristics considered for future clinical applications.

The use of artificial intelligence in computed tomography image reconstruction - A literature review

BACKGROUND AND PURPOSE

The use of AI in the process of CT image reconstruction may improve image quality of resultant images and therefore facilitate low-dose CT examinations.

METHODS

Articles in this review were gathered from multiple databases (Google Scholar, Ovid and Monash University Library Database). A total of 17 articles regarding AI use in CT image reconstruction was reviewed, including 1 white paper from GE Healthcare.

RESULTS

DLR algorithms performed better in terms of noise reduction abilities, and image quality preservation at low doses when compared to other reconstruction techniques.

CONCLUSION

Further research is required to discuss clinical application and diagnostic accuracy of DLR algorithms, but AI is a promising dose-reduction technique with future computational advances.

The Crashing Obese Patient

The obesity pandemic now affects hundreds of millions of people worldwide. As obesity rates continue to increase, emergency physicians are called on with increasing frequency to resuscitate obese patients. This article discusses important anatomic, physiologic, and practical challenges imposed by obesity on resuscitative care. Impacts on hemodynamic monitoring, airway and ventilator management, and pharmacologic therapy are discussed. Finally, several important clinical scenarios (trauma, cardiac arrest, and sepsis), in which alterations to standard treatments may benefit obese patients, are highlighted.

Rapid kVp-switching DECT portal venous phase abdominal CT scans in patients with large body habitus: image quality considerations

PURPOSE

To assess the diagnostic image quality and material decomposition characteristics of portal venous phase abdominal CT scans performed on rapid kVp-switching DECT (rsDECT) in patients with large body habitus.

METHODS

We retrospectively included consecutive patients with large body habitus (≥ 90 kg) undergoing portal venous phase abdominal CT scans on rsDECT scanners between Sep 2014 and March 2018. Qualitative and quantitative assessment of the DECT data sets [65 keV monoenergetic, material density iodine (MD-I) and material density water (MD-W) images] was performed for determination of image quality (IQ) and image noise. Correlation of qualitative assessment scores with weight, BMI and patients' diameter were calculated using Pearson correlation test. Optimal thresholds were calculated using AUC and Youden index to define most appropriate size cut off, below which the IQ of material density images is largely acceptable.

RESULTS

The 65 keV monoenergetic images were of diagnostic quality (diagnostic acceptability, DA ≥ 3) in 97.8% of patients (n = 91/93). However, there was significant IQ degradation of MD-I images in 20.4% (n = 19/93, DA < 3) of patients. Similarly, there was significant degradation (DA < 3) of MD-W images in 26.9% (25/92). Clinically significant artifacts (PA ≥ 3/4) were seen in 31% (n = 29/93) and 32.3% (30/93) of MD-I and MD-W images respectively. Optimal threshold for diagnostic acceptability of MD-I images were 110 kg for weight and 33.5 kg/m² for BMI.

CONCLUSION

Rapid kVp-switching DECT provides diagnostically acceptable monoenergetic images for patients with large body habitus (≥ 90 kg). There is degradation of IQ in the material density specific images particularly in patients weighing > 110 kg and with BMI > 33.5 kg/m², due to higher number of artifacts.

Multi-energy CT imaging for large patients using dual-source photon-counting detector CT

Multi-energy CT imaging of large patients with conventional dual-energy (DE)-CT using an energy-integrating-detector (EID) is challenging due to photon starvation-induced image artifacts, especially in lower tube potential (80-100 kV) images. Here, we performed phantom experiments to investigate the performance of DECT for morbidly obese patients, using an iodine and water material decomposition task as an example, on an emulated dual-source (DS)-photon-counting-detector (PCD)-CT, and compared its performance with a clinical DS-EID-CT. An abdominal CT phantom with iodine inserts of different concentrations was wrapped with tissue-equivalent gel layers to emulate a large patient (50 cm lateral size). The phantom was scanned on a research whole-body single-source (SS)-PCD-CT (140 kV tube potential), a DS-PCD-CT (100/Sn140 kV; Sn140 indicates 140 kV with Sn filter), and a clinical DS-EID-CT (100/Sn140 kV) with the same radiation dose. Phantom scans were repeated five times on each system. The DS-PCD-CT acquisition was emulated by scanning twice on the SS-PCD-CT using different tube potentials. The multi-energy CT images acquired on each system were then reconstructed, and iodine- and water-specific images were generated using material decomposition. The root-mean-square-error (RMSE) between true and measured iodine concentrations were calculated for each system and compared. The images acquired on the DS-EID-CT showed severe artifacts, including ringing, reduced uniformity, and photon starvation artifacts, especially for low-energy images. These were largely reduced in DS-PCD-CT images. The CT number difference that was measured using regions-of-interest across field-of-view were reduced from 20.3 ± 0.9 (DS-EID-CT) to 2.5 ± 0.4 HU on DS-PCD-CT, showing improved image uniformity using DS-PCD-CT. Iodine RMSE was reduced from 3.42 ± 0.03 mg ml^-1 (SS-PCD-CT) and 2.90 ± 0.03 mg ml^-1 (DS-EID-CT) to 2.39 ± 0.05 mg ml^-1 using DS-PCD-CT. DS-PCD-CT out-performed a clinical DS-EID-CT for iodine and water-based material decomposition on phantom emulating obese patients by reducing image artifacts and improving iodine quantification (RMSE reduced by 20%). With DS-PCD-CT, multi-energy CT can be performed on large patients that cannot be accommodated with current DECT.

Deep Learning Versus Iterative Reconstruction for CT Pulmonary Angiography in the Emergency Setting: Improved Image Quality and Reduced Radiation Dose

To compare image quality and the radiation dose of computed tomography pulmonary angiography (CTPA) subjected to the first deep learning-based image reconstruction (DLR) (50%) algorithm, with images subjected to the hybrid-iterative reconstruction (IR) technique (50%). One hundred forty patients who underwent CTPA for suspected pulmonary embolism (PE) between 2018 and 2019 were retrospectively reviewed. Image quality was assessed quantitatively (image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR)) and qualitatively (on a 5-point scale). Radiation dose parameters (CT dose index, CTDI_vol; and dose-length product, DLP) were also recorded. Ninety-three patients were finally analyzed, 48 with hybrid-IR and 45 with DLR images. The image noise was significantly lower and the SNR (24.4 ± 5.9 vs. 20.7 ± 6.1) and CNR (21.8 ± 5.8 vs. 18.6 ± 6.0) were significantly higher on DLR than hybrid-IR images (p < 0.01). DLR images received a significantly higher score than hybrid-IR images for image quality, with both soft (4.4 ± 0.7 vs. 3.8 ± 0.8) and lung (4.1 ± 0.7 vs. 3.6 ± 0.9) filters (p < 0.01). No difference in diagnostic confidence level for PE between both techniques was found. CTDI_vol (4.8 ± 1.4 vs. 4.0 ± 1.2 mGy) and DLP (157.9 ± 44.9 vs. 130.8 ± 41.2 mGy∙cm) were lower on DLR than hybrid-IR images. DLR both significantly improved the image quality and reduced the radiation dose of CTPA examinations as compared to the hybrid-IR technique.

Weight-Adjusted Contrast Administration in the Computed Tomography Evaluation of Pulmonary Embolism

INTRODUCTION

Computed tomography pulmonary angiogram (CTPA) is widely considered the gold standard for diagnosis of pulmonary embolism (PE) with previous studies demonstrating high sensitivity and specificity. Despite this, nondiagnostic and indeterminate CTPA rates of 5%-26% remain a concern. As part of a continuing quality assurance program, a new weight-adjusted contrast dose and increased administration rate CTPA protocol was studied with an aim to improve diagnostic accuracy of PE evaluation.

METHODS

A total of 2,398 CTPA examinations were reviewed to assess pulmonary arterial enhancement and PE yield in this retrospective study. Between 1 August 2014 and 1 August 2015, 1,133 patients received a fixed-volume (60 mL) contrast dose technique at 4 mL/s (protocol A). A new protocol was then implemented as part of a continuing quality assurance program. Between 15 September 2015 and 15 September 2016, 1,265 patients received a weight-adjusted contrast dose (1 mL/kg) and increased administration rate (5 mL/s) CTPA technique (protocol B). Studies were classed into categories based on quality of study; diagnostic: HU > 211, nondiagnostic: HU < 211 and PE yield; positive, negative, and indeterminate. These variables were compared with cross-sectional surface area to assess the relationship between patient habitus, CTPA diagnostic quality, and PE yield.

RESULTS

A weight-adjusted contrast dose and increased administration rate CTPA protocol (protocol B) resulted in a significant increase in mean PA enhancement (P < .0001), 55.23% decrease in nondiagnostic studies and 43.04% decrease in indeterminate studies. Protocol B demonstrated increased positive and negative CTPA rates with decreased indeterminate rates from 12.38% to 7.04%. Comparison with cross-sectional area demonstrated significant increase in proportion of diagnostic studies and reduction in nondiagnostic and indeterminate CTPAs using protocol B in obese patients.

CONCLUSIONS

A weight-adjusted contrast dose and increased administration rate CTPA protocol can significantly increase PA enhancement, especially in obese patients, resulting in greater high-quality and fewer nondiagnostic and indeterminate CTPA examinations. A CTPA protocol with a higher rate of conclusive examinations can provide greater confidence in PE evaluation for reporting radiologists and accurate clinical decision-making pathways for referring physicians.

[Diagnostic and therapeutic management of venous thromboembolic disease in obese patients]

Despite the high proportion of obese patients this population remains understudied in the field of venous thromboembolic disease (VTE). Obesity is a risk factor for pulmonary embolism and/or deep vein thrombosis, especially when it is associated with other risk factors for VTE. Currently there is no validated diagnostic algorithm for VTE in the population of obese patients. Moreover, imaging examinations can be of poor quality and inconclusive. In the prevention of VTE, data concerning obese patients are mainly based on low-level studies. Apart from the context of bariatric surgery, an adjustment of heparin doses according to the weight of the patient is proposed only on a case-by-case basis. According to the current guidelines, therapeutic fixed dose oral anticoagulants should not be prescribed for patients with weights exceeding 120kg or a body mass index>40kg/m². Heparin doses should be weight adjusted and monitored with anti-Xa activity. Anti vitamin K can be prescribed but require INR monitoring. Therefore, new studies specifically dedicated to obese patients are required in the field of VTE for better diagnostic and therapeutic management.

The Challenges of Ultrasound-guided Thoracic Paravertebral Blocks in Rib Fracture Patients

Thoracic paravertebral blocks (TPVBs) provide an effective pain relief modality in conditions where thoracic epidurals are contraindicated. Historically, TPVBs were placed relying solely on the landmark-based technique, but the availability of ultrasound imaging makes it a valuable and practical tool during the placement of these blocks. TPVBs also provide numerous advantages over thoracic epidurals, namely, minimal hypotension, absence of urinary retention, lack of motor weakness, and remote risk of an epidural hematoma. Utilization of both landmark-based and ultrasound-guided techniques may increase the successful placement of a TPVB. This article reviews relevant sonoanatomy as it pertains to TPVBs. However, certain patient-related issues, including pneumothoraces, surgical emphysema, body habitus, and transverse process fractures, all may make imaging with ultrasound challenging. The changes noted on ultrasound imaging as a result of these issues will be further described in this review.

Non-enhanced magnetic resonance imaging as a surveillance tool for hepatocellular carcinoma: Comparison with ultrasound

BACKGROUND & AIMS

Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that patients with inadequate ultrasonography be assessed by alternative imaging modalities. Non-enhanced MRI has potential as a surveillance tool based on the short scan times required and the absence of contrast agent-associated risks. This study compared the performance of non-enhanced MRI and ultrasonography for HCC surveillance in high-risk patients.

METHODS

We included 382 high-risk patients in a prospective cohort who underwent 1 to 3 rounds of paired gadoxetic acid-enhanced MRI and ultrasonography. Non-enhanced MRI, consisting of diffusion-weighted imaging (DWI) and T2-weighted imaging, was simulated and retrospectively analyzed, with results considered positive when lesion(s) ≥1 cm showed diffusion restriction or mild-moderate T2 hyperintensity. Ultrasonography results were retrieved from patient records. HCC was diagnosed histologically and/or radiologically. Sensitivity, positive predictive value (PPV), specificity, and negative predictive value (NPV) were evaluated using generalized estimating equations.

RESULTS

Forty-eight HCCs were diagnosed in 43 patients. Per-lesion and per-exam sensitivities of non-enhanced MRI were 77.1% and 79.1%, respectively, which were higher than those achieved with ultrasonography (25.0% and 27.9%, respectively, p <0.001). Specificities of non-enhanced MRI (97.9%) and ultrasonography (94.5%) differed significantly (p <0.001). NPV was higher for non-enhanced MRI (99.1%) than ultrasonography (96.9%). Per-lesion and per-exam PPVs were higher for non-enhanced MRI (56.9% and 61.8%, respectively) than for ultrasonography (16.7% and 17.7%, respectively). The estimated scan time of non-enhanced MRI was <6 min.

CONCLUSION

Based on its good performance, short scan times, and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients.

LAY SUMMARY

Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that selected patients with inadequate surveillance on ultrasonography be assessed by alternative imaging modalities such as computed tomography or magnetic resonance imaging (MRI). Herein, we show that MRI without contrast agents performed significantly better than ultrasonography for HCC surveillance in high-risk patients. Given this good performance, as well as short scan times and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients.

Application of Low Tube Voltage, Low-concentration Contrast Agent Using a 320-row CT in Coronary CT Angiography: Evaluation of Image Quality, Radiation Dose and Iodine Intake

The effect of low voltage and low concentration contrast agent on image quality of coronary CT angiography, radiation dose and iodine intake was evaluated. A total of 121 patients with body mass index (BMI) <26 kg/m² and heart rate (HR) <70 beats/min were randomly divided into four groups: group A (n=31, 80 kVp, 270 mgI/mL); group B (n=33, 100 kVp, 270 mgI/mL); group C (n=30, 100 kVp, 320 mgI/mL); group D (n=27, 100 kVp, 400 mgI/mL). The automatic current modulation system and the iterative algorithm for reconstruction were adopted in each group. The CT values and SD values of the aortic root (AR), subcutaneous fat, left coronary artery opening (LCA), and right coronary artery opening (RCA) were measured in all groups, the signal-to-noise ratio (SNR) and contrast noise ratio (CNR) were calculated, and effective radiation dose and iodine intake were recorded. The subjective assessment for image quality was performed by two physicians using a 4-point scale. The results were compared using the one-way ANOVA and rank sum tests. The image quality of the four groups met the clinical diagnostic requirements. The CT values of AR in groups A, B, C, and D were 537.6±71.4, 447.2±81.9, 445.2±64.9 and 518.5±94.9 Hu, respectively, with no significant difference between group A and group D, or between group B and group C, while CT values in groups B and C were significantly lower than those in groups A and D (P<0.05). In groups A, B, C, and D, the LCA SNR values were 22.7±9.1, 23.3±9.1, 23.3±7.7 and 26.6±8.9, and the RCA CNR values were 26.9±9.8, 28.5±11.4, 27.7±8.8 and 32.1±10.6, respectively. The AR visual scores in groups A, B, C and D were 3.8±0.2, 3.9±0.3, 3.9±0.3 and 4.0±0.3, respectively. There were no significant differences in SNR, CNR and visual score among the four groups (P>0.05). The radiation doses in groups A, B, C and D were 2.6±1.4, 3.6±1.8, 4.9±3.5 and 4.9±2.8 mSv, respectively. The radiation dose in group A was significantly less than that in the rest three groups (P<0.05). The iodine intakes in groups A, B, C and D were 14.9±1.5, 15.0±1.5, 17.7±2.0 and 18.1±2.5 g, respectively. There was no significant difference in the intake of iodine between groups C and D, or between groups A and B, while iodine intake in groups A and B were significantly reduced as compared with that in groups C and D (P<0.05). It was concluded that for patients with low BMI and controlled HR, compared to 100 kVp tube voltage combined with multiple concentration contrast agents, 80 kVp combined with 270 mgI/mL contrast agent is enough to ensure the quality of the images, and can reduce the radiation dose significantly, while reducing the amount of iodine intake notably, thus reducing the incidence of adverse reaction.

Impact of Patient Size and Radiation Dose on Accuracy and Precision of Iodine Quantification and Virtual Noncontrast Values in Dual-layer Detector CT-A Phantom Study

RATIONALE AND OBJECTIVES

Iodine quantification (IQ) and virtual noncontrast (VNC) images produced by dual-energy CT (DECT) can be used for various clinical applications. We investigate the performance of dual-layer DECT (DLDECT) in different phantom sizes and varying radiation doses and tube voltages, including a low-dose pediatric setting.

MATERIALS AND METHODS

Three phantom sizes (simulating a 10-year-old child, an average, and a large-sized adult) were scanned with iodine solution inserts with concentrations ranging 0-32 mg/ml, using the DLDECT. Each phantom size was scanned with CTDIvol 2-15 mGy at 120 and 140 kVp. The smallest phantom underwent additional scans with CTDIvol 0.9-1.8 mGy. All scans were repeated 3 times. Each iodine insert was analyzed using VNC and IQ images for accuracy and precision, by comparison to known values.

RESULTS

For scans from 2 to 15 mGy mean VNC attenuation and IQ error in the iodine inserts in the small, medium, and large phantoms was 1.2 HU ± 3.2, -1.2 HU ± 14.9, 2.6 HU ± 23.6; and +0.1 mg/cc ± 0.4, -0.9 mg/cc ± 0.9, and -1.8 mg/cc ± 1.8, respectively. In this dose range, there were no significant differences (p ≥ 0.05) in mean VNC attenuation or IQ accuracy in each phantom size, while IQ was significantly less precise in the small phantom at 2 mGy and 10 mGy (p < 0.05). Scans with CTDIvol 0.9-1.8 mGy in the small phantom showed a limited, but statistically significantly lower VNC attenuation precision and IQ accuracy (-0.5 HU ± 5.3 and -0.3 mg/cc ± 0.5, respectively) compared to higher dose scans in the same phantom size.

CONCLUSION

Performance of iodine quantification and subtraction by VNC images in DLDECT is largely dose independent, with the primary factor being patient size. Low-dose pediatric scan protocols have a significant, but limited impact on IQ and VNC attenuation values.

Body mass index and B-lines on lung ultrasonography in chronic and acute heart failure

AIMS

Increased body mass index (BMI) is common in heart failure (HF) patients and is associated with lower levels of N-terminal pro-brain natriuretic peptide (NT-proBNP). We evaluated the influence of BMI on lung ultrasonography (LUS) findings indicative of pulmonary congestion (i.e. B-lines) in patients with chronic and acute HF (AHF).

METHODS AND RESULTS

We analysed ambulatory chronic HF (n = 118) and hospitalized AHF (n = 177) patients (mean age 70 years, 64% men, mean BMI 29 kg/m² , mean ejection fraction 42%) undergoing echocardiography and LUS in eight chest zones. B-lines and chest wall thickness (skin to pleura) on ultrasound were quantified offline and blinded to clinical findings. NT-proBNP was available in AHF patients (n = 167). In chronic HF, B-line number decreased by 18% per 5 unit increase in BMI [95% confidence interval (CI) -35% to +5%, P = 0.11]. In AHF, the number of B-lines decreased by 12% per 5 unit increase in BMI (95% CI -19% to -5%, P = 0.001), whereas NT-proBNP concentration decreased by 28% per 5 unit increase in BMI (95% CI -40% to -16%, P < 0.001). For AHF, B-line number declined to a lesser degree than NT-proBNP concentration with increasing BMI (P = 0.020), and >6 B-lines were observed in half of AHF patients with severe obesity. There was an inverse relationship between B-line number and chest wall thickness, and this association varied by chest region.

CONCLUSIONS

Despite an inverse relationship between B-lines and BMI, B-lines declined to a lesser degree than NT-proBNP with increasing BMI. These data suggest that LUS may be useful in patients with HF despite obesity.

Challenges and impact of patient obesity in radiation therapy practice

INTRODUCTION

The prevalence of obesity is rapidly increasing globally and has tripled between 1975 and 2016. Obesity is reported within the literature as having a significant impact on medical practice, professionals, imaging departments and healthcare systems. It is not known how this epidemic will impact radiation therapists' working environment and practice. The aim of this study is to explore the perceived challenges and impacts of patient obesity on radiation therapy practice from the perception of radiation therapists.

METHODS

All radiation therapists working in the Republic of Ireland were invited to participate. Two focus groups were conducted with 6 and 7 participants respectively. A seven staged method of analysis, using a computerised long table approach was developed and used to analyse the data and create themes related to radiation therapists' perception of managing obese patients.

RESULTS

Perceived challenges from the radiation therapists were difficulties; (1) Setting up the patient (2) Imaging (3) communication and emotional impact.

CONCLUSION

An array of concerns were raised during this research about the increase and impact of obese patients on radiation therapists working environment. This study suggests that obese patients can present additional challenges to radiation therapists' current work practices. It is imperative that we recognise the additional challenges this patient cohort add to daily workflow. Further research is needed to identify the common key issues and how to manage this specific patient group.

IMPLICATIONS FOR PRACTICE

At the moment there are no specific management strategies/policies in place for managing obese patients; this study suggests that it is something we need to consider implementing as standard in radiation therapy departments.

Obesity is associated with a reduced odds for blunt intra-abdominal injuries in children

OBJECTIVES

Children with obesity may possess unique injury characteristics that may affect their emergency care. To better understand this relationship, we investigated the association of obesity in pediatric trauma patients and intra-abdominal injuries (IAIs) and routinely utilized emergency department (ED) diagnostic procedures (computed tomography (CT) scans and ultrasound (US) examinations).

METHODS

This secondary data analysis utilized Pediatric Emergency Care Applied Research Network (PECARN) data from 2007 to 2010. Since height data were not available, children (2-17 years) with obesity were defined using weight-for-age percentiles. Non-parametric testing determined potential confounders. Adjusted odds ratios (aOR) were calculated using binary logistic regression for weight status and IAIs and diagnostic procedures.

RESULTS

There were 3846 patients with actual weight recorded: 3301 (85.8%) children without obesity and 545 (14.2%) with obesity. Children with obesity had decreased odds for IAI after adjusting for race, mechanical force injury (MFI) type, vomiting, and abdominal wall trauma (adjusted odds ratio (aOR)=0.58 (95% CI 0.35-0.97); p-value=0.04). Patients with obesity had reduced odds for a CT examination. No association was found between obesity status and US utilization. African-American patients had decreased odds for IAIs, CT scans and US examinations after adjustment which could be related to MFI type.

CONCLUSIONS

Obesity appears to reduce the odds for pediatric IAIs and CT scans, but not for US examinations. Selection bias is possible due to injury severity and missing or excluded weight data. Further research is needed in other pediatric populations with obesity and blunt injuries.

Role of CT imaging in left atrial appendage occlusion for the WATCHMAN™ device

Computed tomography (CT) plays a key role in the peri-procedural planning of left atrial appendage occlusion (LAAO) device placement and post-procedural evaluation. The geometric variability of the interatrial septum, left atrium, and the left atrial appendage morphology can be fully visualized and intuitively appreciated through CT-derived, patient-specific 3D model unique to each individual's anatomy. This review further defines the strengths and limitations of CT peri-procedural imaging in the planning of LAAO.

Radioprotective garment-inspired biodegradable polymetal nanoparticles for enhanced CT contrast production

Numerous formulations of nanoparticle-based X-ray computed tomography (CT) contrast agents made of heavy metal elements are under investigation for their ability to provide improved CT imaging. Thus far, most experimental nanoparticle-based CT contrast agents have been developed with atoms of a single element. However, inspired by the composites formed from multiple elements used in radioprotective garments, we hypothesized that contrast agents made of several elements whose K-edge energies are spaced out in the high photon flux region could achieve high, broadband X-ray attenuation across the energies used in X-ray source spectra. Herein, we synthesized sub-5 nm core inorganic nanoparticles containing gold, tantalum, and cerium, and encapsulated them in polymeric nanoparticles to form polymetal nanoparticles (PMNP). We found that PMNP with multiple payload elements generate higher and more stable CT contrast than contrast agents made from a single contrast generating material, demonstrating the potential benefits of incorporating multiple suitable elements as CT contrast payloads.

Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy

OBJECTIVES

To compare clinical outcomes in patients who underwent percutaneous nephrolithotomy (PCNL) with renal tract dilatation performed under fluoroscopic guidance vs renal tract dilatation with ultrasound guidance.

PATIENTS AND METHODS

We conducted a prospective observational cohort study, enrolling successive patients undergoing PCNL between July 2015 and March 2018. Included in this retrospective analysis were cases where the renal puncture was successfully obtained with ultrasound guidance. Cases were then grouped according to whether fluoroscopy was used to guide renal tract dilatation or not. All statistical analyses were performed using Stata version 15.1 including univariate (Fisher's exact test, Welch's t-test) and multivariate analyses (binomial logistic regression, ordinal logistic regression, and linear regression).

RESULTS

A total of 176 patients underwent PCNL with successful ultrasonography-guided renal puncture, of whom 38 and 138 underwent renal tract dilatation with fluoroscopic vs ultrasound guidance, respectively. There were no statistically significant differences in patient age, gender, body mass index (BMI), preoperative hydronephrosis, stone burden, procedure laterality, number of dilated tracts, and calyceal puncture location between the two groups. Among ultrasound tract dilatations, a higher proportion of patients were placed in the modified dorsal lithotomy position as opposed to prone, and a significantly shorter operating time was observed. Only modified dorsal lithotomy position remained statistically significant after multivariate regression. There were no statistically significant differences in postoperative stone clearance, complication rate, or intra-operative estimated blood loss. A 5-unit increase in a patient's BMI was associated with 30% greater odds of increasingly severe Clavien-Dindo complications. A 5-mm decrease in the preoperative stone burden was associated with 20% greater odds of stone-free status. No variables predicted estimated blood loss with statistical significance.

CONCLUSIONS

Renal tract dilatation can be safely performed in the absence of fluoroscopic guidance. Compared to using fluoroscopy, the present study demonstrated that ultrasonography-guided dilatations can be safely performed without higher complication or bleeding rates. This can be done using a variety of surgical positions, and future studies centred on improving dilatation techniques could be of impactful clinical value.

PATIENT DOSE IN DIGITAL RADIOGRAPHY UTILISING BMI CLASSIFICATION

Dose audit is important towards optimisation of patients' radiation protection in diagnostic radiography. In this study, the effect of the body mass index (BMI) on radiation dose received by 1869 adult patients undergoing chest, abdomen, lumbar spine, kidneys and urinary bladder (KUB) and pelvis radiography in an X-ray room with a digital radiography system was investigated. Patients were categorised into three groups (normal, overweight and obese) based on the BMI values. The patients' entrance surface air kerma (ESAK) and the effective dose (ED) were calculated based on the X-ray tube output, exposure parameters and technical data, as well as utilising appropriate conversion coefficients of the recorded kerma area product (KAP) values. The local diagnostic reference levels (LDRLs) were established at the 75th percentile of the distribution of ESAK and KAP values. Statistically, a significant increase was found in ESAK, KAP and ED values, for all examinations, both for overweight and obese patients compared to normal patients (Mann-Whitney test, p < 0.0001). Regarding the gender of the patients, a statistically significant increase was found in the dose values for male patients compared to female patients, except for the chest LAT examinations (Mann-Whitney test, p = 0.06). The percentage increase for chest PA, chest LAT, abdomen AP, lumbar spine AP, lumbar spine LAT, pelvis AP and KUB AP in overweight patients was 75%, 100%, 136%, 130%, 70%, 66% and 174% for median ESAK, 67%, 81%, 135%, 134%, 85%, 63% and 172% for median KAP, as well as 89%, 54%, 146%, 138%, 82%, 57% and 183% for median ED values, respectively. For obese patients, the corresponding increases were 200%, 186%, 459%, 345%, 203%, 150% and 785% for median ESAK, 200%, 185%, 423%, 357%, 227%, 142% and 597% for median KAP, as well as 222%, 156%, 446%, 363%, 218%, 136% and 625% for median ED. The corresponding LDRLs for overweight patients were 0.17 mGy, 1.21 mGy, 3.74 mGy, 7.70 mGy, 7.99 mGy, 4.07mGy, 5.03 mGy and 0.13 Gy cm2, 0.69 Gy cm2, 2.35 Gy cm2, 2.10 Gy cm2, 2.59 Gy cm2, 2.13 Gy cm2, 2.49 Gy cm2 in terms of ESAK and KAP values, respectively, while in the case of obese patients were 0.28 mGy, 1.82 mGy, 7.26 mGy, 15.10 mGy, 13.86 mGy, 6.89 mGy, 13.40 mGy and 0.21 Gy cm2, 1.10 Gy cm2, 4.68 Gy cm2, 4.01 Gy cm2, 4.80 Gy cm2, 3.27 Gy cm2, 6.02 Gy cm2, respectively. It can be concluded that overweight and obese patients received a significantly increased radiation dose. Careful adjustment of imaging protocols is needed for these patients to reduce patient dose, while keeping the image quality at an acceptable level. Additional studies need to be conducted for these patient groups, that could further contribute to the development of radiation protection culture in diagnostic radiography.

In vivo photoacoustic imaging of major blood vessels in the pancreas and liver during surgery

Abdominal surgeries carry considerable risk of gastrointestinal and intra-abdominal hemorrhage, which could possibly cause patient death. Photoacoustic imaging is one solution to overcome this challenge by providing visualization of major blood vessels during surgery. We investigate the feasibility of in vivo blood vessel visualization for photoacoustic-guided liver and pancreas surgeries. In vivo photoacoustic imaging of major blood vessels in these two abdominal organs was successfully achieved after a laparotomy was performed on two swine. Three-dimensional photoacoustic imaging with a robot-controlled ultrasound (US) probe and color Doppler imaging were used to confirm vessel locations. Blood vessels in the in vivo liver were visualized with energies of 20 to 40 mJ, resulting in 10 to 15 dB vessel contrast. Similarly, an energy of 36 mJ was sufficient to visualize vessels in the pancreas with up to 17.3 dB contrast. We observed that photoacoustic signals were more focused when the light source encountered a major vessel in the liver. This observation can be used to distinguish major blood vessels in the image plane from the more diffuse signals associated with smaller blood vessels in the surrounding tissue. A postsurgery histopathological analysis was performed on resected pancreatic and liver tissues to explore possible laser-related damage. Results are generally promising for photoacoustic-guided abdominal surgery when the US probe is fixed and the light source is used to interrogate the surgical workspace. These findings are additionally applicable to other procedures that may benefit from photoacoustic-guided interventional imaging of the liver and pancreas (e.g., biopsy and guidance of radiofrequency ablation lesions in the liver).

Optimizing Projectional Radiographic Imaging of the Abdomen of Obese Patients: An e-Delphi Study

PURPOSE

Obesity is increasing in prevalence globally, with increased demands placed on radiology departments to image obese patients to assist with diagnosis and management. The aim of this study was to determine perceived best practice techniques currently used in clinical practice for projectional radiography of the abdomen for obese patients with the aim to help elucidate areas for future research and education needs in this field.

EXPERIMENTAL DESIGN

A two round e-Delphi study was undertaken to establish a consensus within a reference group of expert Australian clinical educator diagnostic radiographers (CEDRs). Initially, a conceptual map of issues regarding imaging obese patients was undertaken by analysing interview transcripts of 12 CEDRs. This informed an online questionnaire design used in Delphi rounds 1 and 2. A consensus threshold was set <75% "agreement/disagreement", with 15 and 14 CEDRs participating in rounds 1 and 2, respectively.

RESULTS

Seven of the 11 statements reach consensus after round 2. Consensus on using a combination of higher peak kilovoltage (kVp) and milliampere-seconds (mAs) to increase radiation exposure increased source-to-image distance and tighter collimation was achieved. There was no consensus regarding patient positioning practices or patient communication strategies. The expert group reported the importance of personal confidence and treating patients as individuals when applying techniques.

CONCLUSION

Diversity of experts' opinions and current practice may be due to the variations in obese patients' size and presentation. Therefore, there is a need for extensive empirical evidence to underpin practice and education resources for radiographers when imaging obese patients.

Dual-energy CT in the obese: a preliminary retrospective review to evaluate quality and feasibility of the single-source dual-detector implementation

PURPOSE

To determine the feasibility of performing dual-energy CT with a single-source spectral detector system in obese patients.

MATERIALS AND METHODS

Retrospective, IRB-approved review of 28 patients weighing ≥ 270 lbs (122 kg) who underwent CT of the abdomen on a single-source spectral detector system was performed. Two blinded, independent radiologists rated relative preference between conventional CT images taken at 120 kVp (CCT120) and monoenergetic 70 keV equivalent (MonoE70) as well as iodine map image quality in the spleen, pancreas, kidneys, and liver. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between conventional CT and MonoE70 images and correlated with body habitus markers of weight, height, and abdominal diameter.

RESULTS

MonoE70 images were preferred by radiologists 100% of the time (1-sample t test, p < 0.0001) over conventional CCT120 images. Noise was significantly lower; SNR and CNR were significantly higher in MonoE70 images than in CCT120 images (paired t tests, p < 0.0001). Mean iodine map rating (scale 1-5) was 4.54 ± 0.58, denoting near homogenous and complete iodine mapping through the spleen, pancreas, kidneys, and liver for the majority of patients. Body habitus markers were not significantly correlated with image preference score; noise; MonoE70 SNR; MonoE70 CNR; change in noise, SNR, or CNR from CCT120 to MonoE70, or iodine map quality; ordinal and linear regression, p = 0.2547, p = 0.6837, p =  0.1888, p = 0.5489, p = 0.9830, p = 0.8849, p = 0.8741, p = 0.1522, respectively.

CONCLUSION

The single-source spectral detector implementation of dual-energy CT provides viable, high-quality imaging for obese patients.