Sustainable volume sweep imaging lung teleultrasound in Peru: Public health perspectives from a new frontier in expanding access to imaging.

Background: Pulmonary disease is a common cause of morbidity and mortality, but the majority of the people in the world lack access to diagnostic imaging for its assessment. We conducted an implementation assessment of a potentially sustainable and cost-effective model for delivery of volume sweep imaging (VSI) lung teleultrasound in Peru. This model allows image acquisition by individuals without prior ultrasound experience after only a few hours of training. Methods: Lung teleultrasound was implemented at 5 sites in rural Peru after a few hours of installation and staff training. Patients were offered free lung VSI teleultrasound examination for concerns of respiratory illness or research purposes. After ultrasound examination, patients were surveyed regarding their experience. Health staff and members of the implementation team also participated in separate interviews detailing their views of the teleultrasound system which were systematically analyzed for key themes. Results: Patients and staff rated their experience with lung teleultrasound as overwhelmingly positive. The lung teleultrasound system was viewed as a potential way to improve access to imaging and the health of rural communities. Detailed interviews with the implementation team revealed obstacles to implementation important for consideration such as gaps in lung ultrasound understanding. Conclusions: Lung VSI teleultrasound was successfully deployed to 5 health centers in rural Peru. Implementation assessment revealed enthusiasm for the system among members of the community along with important areas of consideration for future teleultrasound deployment. This system offers a potential means to increase access to imaging for pulmonary illness and improve the health of the global community.

Volume sweep imaging lung teleultrasound for detection of COVID-19 in Peru: a multicentre pilot study.

OBJECTIVES: Pulmonary disease is a significant cause of morbidity and mortality in adults and children, but most of the world lacks diagnostic imaging for its assessment. Lung ultrasound is a portable, low-cost, and highly accurate imaging modality for assessment of pulmonary pathology including pneumonia, but its deployment is limited secondary to a lack of trained sonographers. In this study, we piloted a low-cost lung teleultrasound system in rural Peru during the COVID-19 pandemic using lung ultrasound volume sweep imaging (VSI) that can be operated by an individual without prior ultrasound training circumventing many obstacles to ultrasound deployment. DESIGN: Pilot study. SETTING: Study activities took place in five health centres in rural Peru. PARTICIPANTS: There were 213 participants presenting to rural health clinics. INTERVENTIONS: Individuals without prior ultrasound experience in rural Peru underwent brief training on how to use the teleultrasound system and perform lung ultrasound VSI. Subsequently, patients attending clinic were scanned by these previously ultrasound-naïve operators with the teleultrasound system. PRIMARY AND SECONDARY OUTCOME MEASURES: Radiologists examined the ultrasound imaging to assess its diagnostic value and identify any pathology. A random subset of 20% of the scans were analysed for inter-reader reliability. RESULTS: Lung VSI teleultrasound examinations underwent detailed analysis by two cardiothoracic attending radiologists. Of the examinations, 202 were rated of diagnostic image quality (94.8%, 95% CI 90.9% to 97.4%). There was 91% agreement between radiologists on lung ultrasound interpretation among a 20% sample of all examinations (κ=0.76, 95% CI 0.53 to 0.98). Radiologists were able to identify sequelae of COVID-19 with the predominant finding being B-lines. CONCLUSION: Lung VSI teleultrasound performed by individuals without prior training allowed diagnostic imaging of the lungs and identification of sequelae of COVID-19 infection. Deployment of lung VSI teleultrasound holds potential as a low-cost means to improve access to imaging around the world.

Optimizing low contrast volume thoracic CT angiography: From the basics to the advanced.

Contrast-enhanced CT angiography (CTA) is a widely used, noninvasive imaging technique for evaluating cardiovascular structures. Contrast-induced nephrotoxicity is a concern in renal disease; however, the true nephrotoxic potential of iodinated contrast media (CM) is unknown. If a renal impaired patient requires CTA, it is important to protect the kidneys from further harm by reducing total iodinated CM volume while still obtaining diagnostic quality imaging. These same reduced volume CM techniques can also be applied to nonrenal impaired patients in times of CM shortage. This educational review discusses several modifications to CTA that can be adapted to both conventional 64-slice and the newer generation CT scanners which enable subsecond acquisition with a reduced CM volume technique. Such modifications include hardware and software adjustments and changes to both the volume and flow rate of administered CM, with the goal to reduce the dose of CM without compromising diagnostic yield.

Vascular Imaging in the Asymptomatic High-risk Cancer Population: A Role for Thrombosis Screening and Therapy Management.

OBJECTIVES: We retrospectively examined the venous thromboembolism (VTE) events diagnosed in the Prophylaxis of High-Risk Ambulatory Cancer Patients Study (PHACS), a multi-center randomized trial, to assess the value of screening vascular imaging for the diagnosis of incidental VTE in high-risk cancer patients. METHODS: A total of 117 asymptomatic cancer patients with a Khorana score ≥3 starting a new systemic chemotherapy regimen were enrolled in a prospective randomized control trial. Patients underwent baseline venous ultrasound (US) of the lower extremities (LEs) and screening contrast-enhanced chest computed tomography (CT). Those without preexisting VTE were then randomized into observation or dalteparin prophylaxis groups and were screened with serial US every 4 weeks for up to 12 weeks and imaged with contrast-enhanced chest CT at 12 weeks. Any additional imaging performed during the study period was also evaluated for VTE. RESULTS: Baseline prevalence of incidental VTE was 9% (n = 10) with 58% percent of VTEs diagnosed by screening US. Incidence of VTE in the randomized phase of the trial was 16% (n = 16) with 21% (n = 10) of patients in the control arm and 12% (n = 6) of patients in the dalteparin arm developing VTE, a non-significant 9% absolute risk reduction (HR = 0.69, 95% CI 0.23-1.89). Sixty-nine percent of these patients were asymptomatic with 31% of patients diagnosed by screening US. CONCLUSIONS: Adding screening US to routine oncologic surveillance CT in high-risk ambulatory cancer patients with a Khorana score ≥3 can lead to increased VTE detection, with potential for decreased morbidity, mortality, and health care spending.

Lung ultrasound volume sweep imaging for respiratory illness: a new horizon in expanding imaging access.

BACKGROUND: Respiratory illness is a leading cause of morbidity in adults and the number one cause of mortality in children, yet billions of people lack access to medical imaging to assist in its diagnosis. Although ultrasound is highly sensitive and specific for respiratory illness such as pneumonia, its deployment is limited by a lack of sonographers. As a solution, we tested a standardised lung ultrasound volume sweep imaging (VSI) protocol based solely on external body landmarks performed by individuals without prior ultrasound experience after brief training. Each step in the VSI protocol is saved as a video clip for later interpretation by a specialist. METHODS: Dyspneic hospitalised patients were scanned by ultrasound naive operators after 2 hours of training using the lung ultrasound VSI protocol. Separate blinded readers interpreted both lung ultrasound VSI examinations and standard of care chest radiographs to ascertain the diagnostic value of lung VSI considering chest X-ray as the reference standard. Comparison to clinical diagnosis as documented in the medical record and CT (when available) were also performed. Readers offered a final interpretation of normal, abnormal, or indeterminate/borderline for each VSI examination, chest X-ray, and CT. RESULTS: Operators scanned 102 subjects (0-89 years old) for analysis. Lung VSI showed a sensitivity of 93% and a specificity of 91% for an abnormal chest X-ray and a sensitivity of 100% and a specificity of 93% for a clinical diagnosis of pneumonia. When any cases with an indeterminate rating on chest X-ray or ultrasound were excluded (n=38), VSI lung ultrasound showed 92% agreement with chest X-ray (Cohen's κ 0.83 (0.68 to 0.97, p<0.0001)). Among cases with CT (n=21), when any ultrasound with an indeterminate rating was excluded (n=3), there was 100% agreement with VSI. CONCLUSION: Lung VSI performed by previously inexperienced ultrasound operators after brief training showed excellent agreement with chest X-ray and high sensitivity and specificity for a clinical diagnosis of pneumonia. Blinded readers were able to identify other respiratory diseases including pulmonary oedema and pleural effusion. Deployment of lung VSI could benefit the health of the global community.

Lung Ultrasound: The Essentials.

Although US of the lungs is increasingly used clinically, diagnostic radiologists are not routinely trained in its use and interpretation. Lung US is a highly sensitive and specific modality that aids in the evaluation of the lungs for many different abnormalities, including pneumonia, pleural effusion, pulmonary edema, and pneumothorax. This review provides an overview of lung US to equip the diagnostic radiologist with knowledge needed to interpret this increasingly used modality. Supplemental material is available for this article. © RSNA, 2021.

Neoplastic pathology at the crossroads between neck imaging and cardiothoracic imaging.

The thoracic inlet is located at the crossroads between imaging of the neck and the chest. Its location is an important anatomic landmark, serving as the central conducting pathway for many vital structures extending from the neck into the chest and vice versa. Many critical body systems, including the respiratory, lymphatic, neurologic, enteric, musculoskeletal, endocrine, and vascular systems, are located within this region. Neoplasms, both benign and malignant, can arise in any of the body systems located in this area. Due to the small size of this anatomic location, pathology is easily overlooked and imagers should be aware of the imaging appearance of these neoplasms, as well as which imaging modality is the most appropriate for neoplasm evaluation. This article will present an image rich, system-based discussion of the neoplastic pathology that can occur in this region. The anatomy of the thoracic inlet and the non-neoplastic pathology of the thoracic inlet have been covered in our companion article.

Non-neoplastic pathology at the crossroads between neck imaging and cardiothoracic imaging.

The thoracic inlet is located at the crossroads between imaging of the neck and chest. It represents an important anatomic landmark, serving as the central conducting pathway for many vital structures extending from the neck into the chest and vice versa. Many important body systems are located within this region, including the enteric, respiratory, vascular, lymphatic, neurologic, and endocrine systems. A detailed examination of this region is essential when reviewing neck and thoracic imaging. This article will discuss the normal anatomic boundaries of the thoracic inlet and present an image-rich systematic discussion of the non-neoplastic pathology that can occur in this region. The neoplastic pathology of the thoracic inlet will be covered in a companion article.

Lung Ultrasound Volume Sweep Imaging for Pneumonia Detection in Rural Areas: Piloting Training in Rural Peru.

OBJECTIVE: Pneumonia is the leading cause of pediatric mortality worldwide among children 0-5 years old. Lung ultrasound can be used to diagnose pneumonia in rural areas as it is a portable and relatively economic imaging modality with ~95% sensitivity and specificity for pneumonia in children. Lack of trained sonographers is the current limiting factor to its deployment in rural areas. In this study, we piloted training of a volume sweep imaging (VSI) ultrasound protocol for pneumonia detection in Peru with rural health workers. VSI may be taught to individuals with limited medical/ultrasound experience as it requires minimal anatomical knowledge and technical skill. In VSI, the target organ is imaged with a series of sweeps and arcs of the ultrasound probe in relation to external body landmarks. METHODS: Rural health workers in Peru were trained on a VSI ultrasound protocol for pneumonia detection. Subjects were given a brief didactic session followed by hands-on practice with the protocol. Each attempt was timed and mistakes were recorded. Participants performed the protocol until they demonstrated two mistake-free attempts. RESULTS: It took participants a median number of three attempts (range 1-6) to perform the VSI protocol correctly. Time to mastery took 51.4 ± 17.7 min. There were no significant differences among doctors, nurses, and technicians in total training time (P = 0.43) or number of attempts to success (P = 0.72). Trainee age was not found to be significantly correlated with training time (P = 0.50) or number of attempts to success (P = 0.40). CONCLUSION: Rural health workers learned a VSI protocol for pneumonia detection with relative ease in a short amount of time. Future studies should investigate the clinical efficacy of this VSI protocol for pneumonia detection. KEY MESSAGE: A volume sweep imaging (VSI) protocol for pneumonia detection can be taught with minimal difficulty to rural health workers without prior ultrasound experience. No difference was found in training performance related to education level or age. VSI involves no significant knowledge of anatomy or technical skill.

Blood finds a way: pictorial review of thoracic collateral vessels.

In the healthy patient, blood returns to the heart via classic venous pathways. Obstruction of any one of these pathways will result in blood flow finding new collateral pathways to return to the heart. Although significant anatomic variation exists and multiple collateral vessels are often present in the same patient, it is a general rule that the collateral pathways formed are a function of the site of venous blockage. Therefore, knowledge of typical collateral vessel systems can provide insight in localizing venous obstruction and characterizing its severity and chronicity. In addition, knowledge of collateral anatomy can be essential in interventional procedural and/or surgical planning, especially when placing catheters in patients with venous blockage. In this pictorial review, we provide a systematic approach to understanding collateral pathways in patients with venous obstruction in the upper body.

Accuracy of Non-Electrocardiographically Gated Thoracic CT Angiography for Right Atrial and Right Ventricular Enlargement.

PURPOSE: To assess the role of long-axis (LA) and short-axis (SA) measurements of the right atrium (RA) and right ventricle (RV) at non-electrocardiographically (ECG) gated thoracic CT angiography for identification of RA enlargement and RV enlargement. MATERIALS AND METHODS: This study was a retrospective case review of 138 patients who underwent both non-ECG-gated CT angiography and ECG-gated CT angiography concurrently from November 2016 through November 2018. The SA and LA of the RA and RV were measured by two observers blinded to the ECG-gated CT angiography data. ECG-gated CT angiography-derived RA end-systolic and RV end-diastolic volumes were used as standard of reference to derive cutoff values for diagnosis of RA and RV enlargement. RESULTS: In this study, 138 patients were evaluated (70 men, 68 women; mean age, 70.0 years ± 18.4 [standard deviation]; mean body mass index, 29.3 kg/m2 ± 8.1). Of these patients, ECG-gated CT angiography revealed 36.2% had RA enhancement and 19.0% had RV enhancement. The best predictor of RA enhancement was the product of atrial LA and SA measurements, for which a threshold value of 3210 mm2 yielded a 94% sensitivity and 81.8% specificity (area under the curve [AUC], 0.92). A threshold of 55.5 mm for LA diameter had 86% sensitivity and 78.4% specificity in identifying RA enlargement. RV enlargement could be predicted if the SA diameter was greater than 48.5 mm (76.9% sensitivity and 64.9% specificity) and with a body surface area indexed value of 27.0 mm/m2 (92.3% sensitivity and 74.8% specificity [AUC, 0.87]). CONCLUSION: RA and RV enlargement can be accurately diagnosed by using non-ECG-gated CT angiography.© RSNA, 2019Supplemental material is available for this article.

Pictorial review of the pulmonary vasculature: from arteries to veins.

Pathology of the pulmonary vasculature involves an impressive array of both congenital and acquired conditions. While some of these disorders are benign, disruption of the pulmonary vasculature is often incompatible with life, making these conditions critical to identify on imaging. Many reviews of pulmonary vascular pathology approach the pulmonary arteries, pulmonary veins and bronchial arteries as individual topics. The goal of this review is to provide an integrated overview of the high-yield features of all major disorders of the pulmonary vasculature. This approach provides a more cohesive and comprehensive conceptualisation of respiratory pathology. In this review, we present both the salient clinical and imaging features of congenital and acquired disorders of the pulmonary vasculature, to assist the radiologist in identifying pathology and forming a robust differential diagnosis tailored to the presenting patient. TEACHING POINTS: • Abnormalities of the pulmonary vasculature are both congenital and acquired. • Pathology of a single pulmonary vascular territory often affects the entire pulmonary vasculature. • Anomalous pulmonary venous flow is named as a function of its location and severity. • Bronchial arteries often undergo dilatation secondary to cardio-respiratory pathology.

Every second counts: signs of a failing heart on thoracic CT in the ED.

Impending cardiac failure is often difficult to recognize and requires a multidisciplinary approach. Upon arrival in the emergency department, patients are promptly screened for potentially life-threatening conditions through a history and physical examination. In many cases, the diagnosis is not clear until confirmatory laboratory or imaging tests are performed. Unfortunately, patients can rapidly decompensate as this diagnostic information is being obtained. Emergent CT plays a key role in identifying conditions that may result in cardiovascular collapse, including severe congestive heart failure, myocardial infarction, cardiac tamponade, and impending cardiac failure. Characteristic imaging findings can prompt the physician to take immediate action and prepare for resuscitation.

Identification of Left Ventricle Failure on Pulmonary Artery CTA: Diagnostic Significance of Decreased Aortic & Left Ventricle Enhancement.

PURPOSE: This study aimed to identify findings on non-ECG-gated CT pulmonary angiography (CTPA) indicating decreased left ventricle (LV) systolic function, later confirmed by echocardiogram. METHODS: After obtaining institutional review board approval, review was performed of emergency department (ED) patients who had CTPA and follow-up echocardiogram within 48 h, over 18 months. Patients with pulmonary embolus, suboptimal CTPA, arrhythmias or pericardial tamponade were excluded. One hundred thirty-seven patients were identified and divided into cases (LVEF <40%, n = 52) and controls (LVEF >50%, n = 85). Two reviewers performed these analyses: measurement of enhancement in main pulmonary artery (MPA), LV, and aorta; subjective enhancement of LV and aorta (Ao) relative to MPA using a four-point Likert scale; contrast transit time (TD) to trigger CTPA and LV short & long axis dimensions. When available, the most recent N-terminal pro-B-type natriuretic peptide (NT-proBNP) level was recorded. RESULTS: Decreased aortic and LV subjective enhancement were the best predictors of LV systolic dysfunction. For Ao/MPA ratio, an optimal cutoff value of 0.20 resulted in a sensitivity of 0.54 and specificity of 0.93 (AUC = 0.83, 0.78-0.88 95% CI). A threshold of 86.7 HU for Ao enhancement resulted in a sensitivity of 0.68 and specificity of 0.90 (AUC = 0.82, 0.77-0.88 95% CI). A LV short axis diameter of more than 54.3 mm had a sensitivity of 0.62 and specificity of 0.98 (AUC = 0.88, 0.83-0.92 95% CI). For the LV long axis diameter, a cutoff of 87.5 mm resulted in a sensitivity of 0.66 and specificity of 0.84 (AUC = 0.78, 0.72-0.84 95% CI). With bolus timing, cases had a longer TD (13.4 vs. 10.4 s, p < 0.0001). CONCLUSION: Unsuspected LV systolic dysfunction can be recognized on a CTPA by identification of decreased aortic enhancement, LV enlargement and increased TD. This has important diagnostic implications for the patient presenting with shortness of breath, chest pain, or dyspnea.

Imaging of the oesophagus: beyond cancer.

Non-malignant oesophageal diseases are critical to recognize, but can be easily overlooked or misdiagnosed radiologically. In this paper, we cover the salient clinical features and imaging findings of non-malignant pathology of the oesophagus. We organize the many non-malignant diseases of the oesophagus into two major categories: luminal disorders and wall disorders. Luminal disorders include dilatation/narrowing (e.g. achalasia, scleroderma, and stricture) and foreign body impaction. Wall disorders include wall thickening (e.g. oesophagitis, benign neoplasms, oesophageal varices, and intramural hematoma), wall thinning/outpouching (e.g. epiphrenic diverticulum, Zenker diverticulum, and Killian-Jamieson diverticulum), wall rupture (e.g. iatrogenic perforation, Boerhaave Syndrome, and Mallory-Weiss Syndrome), and fistula formation (e.g. pericardioesophageal fistula, tracheoesophageal fistula, and aortoesophageal fistula). It is the role of the radiologist to recognize the classic imaging patterns of these non-malignant oesophageal diseases to facilitate the delivery of appropriate and prompt medical treatment. TEACHING POINTS: • Nonmalignant oesophageal disease can be categorised by the imaging appearance of wall and lumen. • Scleroderma and achalasia both cause lumen dilatation via different pathophysiologic pathways. • Oesophageal wall thickening can be inflammatory, neoplastic, traumatic, or vascular in aetiology.

Dalteparin thromboprophylaxis in cancer patients at high risk for venous thromboembolism: A randomized trial.

BACKGROUND: Ambulatory cancer patients at high-risk for venous thromboembolism (VTE) can be identified using a validated risk score (Khorana score). We evaluated the benefit of outpatient thromboprophylaxis with dalteparin in high-risk patients in a multicenter randomized study. METHODS: Cancer patients with Khorana score≥3 starting a new systemic regimen were screened for VTE and if negative randomized to dalteparin 5000units daily or observation for 12weeks. Subjects were screened with lower extremity ultrasounds every 4weeks on study and with chest CT at 12weeks. The primary efficacy endpoint was all VTE over 12weeks and primary safety endpoint was clinically relevant bleeding events over 13weeks. The study was terminated early due to low accrual. RESULTS: Of 117 enrolled patients, 10 (8.5%) had VTE on baseline screening and were not randomized. Of 98 randomized patients, VTE occurred in 12% (N=6/50) of patients on dalteparin and 21% (N=10/48) on observation (hazard ratio, HR 0.69, 95% CI 0.23-1.89). Major bleeding was similar (N=1) in each arm but clinically relevant bleeding was higher in dalteparin arm (N=7 versus 1 on observation) (HR=7.0, 95% CI 1.2-131.6). There was no difference in overall survival. CONCLUSIONS: Thromboprophylaxis is associated with a non-significantly reduced risk of VTE and significantly increased risk of clinically relevant bleeding in this underpowered study. The Khorana score successfully identifies patients with high incidence of VTE both at baseline and during treatment. Future studies should continue to focus on risk-adapted approaches to reduce the burden of VTE in cancer. TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT00876915.

Contrast opacification on thoracic CT angiography: challenges and solutions.

Contrast flow and enhancement patterns seen on thoracic CT angiography (CTA) can often be challenging and may often reveal more than is immediately apparent. A non-diagnostic CTA following the initial contrast injection can be secondary to many causes; these include both extrinsic factors, such as injection technique/equipment failure (iv cannula, power injector), and intrinsic, patient-related factors. Contrast pressure and flow graphs often contain useful information regarding the etiology of a non-diagnostic scan. Understanding these graphs will help the radiologist plan a repeat contrast injection to overcome the deficiencies of the first injection and thus obtain a diagnostic scan. The current review article outlines normal and abnormal intravenous contrast dynamics, discusses how to recognize etiologies of non-diagnostic scans, and ultimately addresses techniques to overcome obstacles towards obtaining normal contrast opacification of the target vessel. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. Key Points • Using contrast enhancement and flow patterns to identify the cause of a non-diagnostic CTA.• Recognize life threatening causes of altered contrast dynamics such as cardiac asystole.• Non-target vessel opacification may hold key to underlying pathophysiology.