Comparison of the ultra-low-dose Veo algorithm with the gold standard filtered back projection for detecting pulmonary asbestos-related conditions: a clinical observational study

Diagnostic accuracy of low-dose and ultra-low-dose CT in detection of chest pathology: a systematic review

PURPOSE

Studies have evaluated imaging modalities with a lower radiation dose than standard-dose CT (SD-CT) for chest examination. This systematic review aimed to summarize evidence on diagnostic accuracy of these modalities - low-dose and ultra-low-dose CT (LD- and ULD-CT) - for chest pathology.

METHOD

Ovid-MEDLINE, Ovid-EMBASE and the Cochrane Library were systematically searched April 29th-30th, 2019 and screened by two reviewers. Studies on diagnostic accuracy were included if they defined their index tests as 'LD-CT', 'Reduced-dose CT' or 'ULD-CT' and had SD-CT as reference standard. Risk of bias was evaluated on study level using the Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted to compare the diagnostic accuracy measurements.

RESULTS

Of the 4257 studies identified, 18 were eligible for inclusion. SD-CT (3.17 ± 1.47 mSv) was used as reference standard in all studies to evaluate diagnostic accuracy of LD- (1.22 ± 0.34 mSv) and ULD-CT (0.22 ± 0.05 mSv), respectively. LD-CT had high sensitivities for detection of bronchiectasis (82-96%), honeycomb (75-100%), and varying sensitivities for nodules (63-99%) and ground glass opacities (GGO) (77-91%). ULD-CT had high sensitivities for GGO (93-100%), pneumothorax (100%), consolidations (90-100%), and varying sensitivities for nodules (60-100%) and emphysema (65-90%).

CONCLUSION

The included studies found LD-CT to have high diagnostic accuracy in detection of honeycombing and bronchiectasis and ULD-CT to have high diagnostic accuracy for pneumothorax, consolidations and GGO. Summarizing evidence on diagnostic accuracy of LD- and ULD-CT for other chest pathology was not possible due to varying outcome measures, lack of precision estimates and heterogeneous study design and methodology.

Wide-volume versus helical acquisition in unenhanced chest CT: prospective intra-patient comparison of diagnostic accuracy and radiation dose in an ultra-low-dose setting

OBJECTIVES

Diagnostic performance and potential radiation dose reduction of wide-area detector CT sequential acquisition ("wide-volume" acquisition (WV)) in unenhanced chest examination are unknown. This study aims to assess the image quality, the diagnostic performance, and the radiation dose reduction of WV mode compared with the classical helical acquisition for lung parenchyma analysis in an ultra-low-dose (ULD) protocol.

METHODS

After Institutional Review Board Approval and written informed consent, 64 patients (72% men; 67.6 ± 9.7 years old; BMI 26.1 ± 5.3 kg/m²) referred for a clinically indicated unenhanced chest CT were prospectively included. All patients underwent, in addition to a standard helical acquisition (120 kV, automatic tube current modulation), two ULD acquisitions (135 kV, fixed tube current at 10 mA): one in helical mode and one in WV mode. Image noise, subjective image quality (5-level Likert scale), and diagnostic performance for the detection of 9 predetermined parenchymal abnormalities were assessed by two radiologists and compared using the chi-square or Fisher non-parametric tests.

RESULTS

Subjective image quality (4.2 ± 0.7 versus 4.2 ± 0.8, p = 0.56), image noise (41.7 ± 8 versus 40.9 ± 8.7, p = 0.3), and diagnostic performance were equivalent between ULD WV and ULD helical. Radiation dose was significantly lower for the ULD WV acquisition (mean dose-length product 14.1 ± 1.3 mGy cm versus 15.8 ± 1.3, p < 0.0001).

CONCLUSION

An additional 11% dose reduction is achieved with the WV mode in ULD chest CT with fixed tube current, with equivalent image quality and diagnostic performance when compared with the helical acquisition.

KEY POINTS

• Image quality and diagnostic performance of ultra-low-dose unenhanced chest CT are identical between wide-volume mode and the reference helical acquisition. • Wide-volume mode allows an additional radiation dose reduction of 11% (mean dose-length product 14.1 ± 1.3 mGy cm versus 15.8 ± 1.3, p < 0.0001).

Work Addiction Test Questionnaire to Assess Workaholism: Validation of French Version

BACKGROUND

Work addiction is a significant public health problem with a growing prevalence. The Work Addiction Risk Test (WART) is the gold standard questionnaire to detect workaholism.

OBJECTIVE

The main objective of this study was to validate the French version of the WART.

METHODS

Questionnaires were proposed to voluntary French workers using the WittyFit software. There were no exclusion criteria. The questionnaire was administered anonymously for initial validity testing and readministered one week later for test-retest reliability. We also assessed the workers' sociodemographic characteristics, as well as other measurements for external validity, such as stress, well-being, and coaddictions to tobacco, alcohol, and cannabis. Several psychometric properties of the French-WART were explored: acceptability, reliability (internal consistency [Cronbach alpha coefficient] and reproducibility [Lin concordance coefficient]), construct validity (correlation coefficients and principal component analysis), and external validity (correlation coefficients).

RESULTS

Among the 1580 workers using WittyFit, 187 (11.83%) agreed to complete the WART questionnaire. Of those, 128 completed the test-retest survey (68.4%). Acceptability found that all respondents had fully completed the questionnaire, with few floor or ceiling effects. Reliability was very good with a Cronbach alpha coefficient at .90 (internal consistency) and Lin concordance coefficient at .90 (95% CI .87-.94] with a difference on the retest of .04 (SD 4.9) (95% CI -9.6 to 9.7) (reproducibility). We identified three main dimensions (construct validity). Relationships between WART and stress and well-being confirmed its external validity.

CONCLUSIONS

The French version of the WART is a valid and reliable instrument to assess work addiction with satisfactory psychometric properties. Used in occupational medicine, this tool would allow the diagnosis of work addiction and can be easily implemented in current practice.

Low-voltage chest CT: another way to reduce the radiation dose in asbestos-exposed patients

AIM

To assess whether low voltage chest computed tomography (CT) can be used to successfully diagnose disease in patients with asbestos exposure.

MATERIALS AND METHODS

Fifty-six former employees of the shipbuilding industry, who were candidates to receive a standard-dose chest CT due to their occupational exposure to asbestos, underwent a routine CT. Immediately after this initial CT, they underwent a second acquisition using low-dose chest CT parameters, based on a low potential (80 kV) and limited tube current. The findings of the two CT protocols were compared based on typical diseases associated with asbestos exposure. The kappa coefficient for each parameter and for an overall rating (grouping them based on mediastinal, pleural, and pulmonary findings) were calculated in order to test for correlations between the two protocols.

RESULTS

A good correlation between routine and low-dose CT was demonstrated for most parameters with a mean radiation dose reduction of up to 83% of the effective dose based on the dose-length product between protocols.

CONCLUSIONS

Low-dose chest CT, based on a limited tube potential, is useful for patients with an asbestos exposure background. Low-dose chest CT can be successfully used to minimise the radiation dose received by patients, as this protocol produced an estimated mean effective dose similar to that of an abdominal or pelvis plain film.

[What future for chest x-ray against ultra-low-dose computed tomography?]

Technological improvements, with iterative reconstruction at the foreground, have lowered the radiation dose of a chest CT close to that of a PA and lateral chest x-ray. This ultra-low dose chest CT (ULD-CT) has an image quality that is degraded on purpose, yet remains diagnostic in many clinical indications. Thus, its effectiveness is already validated for the detection and the monitoring of solid parenchymal nodules, for the diagnosis and monitoring of infectious lung diseases and for the screening of pleural lesions secondary to asbestos exposure. Its limitations are the analysis of the mediastinal structures, the severe obesity (BMI>35) and the detection of interstitial lesions. If it can replace the standard chest CT in these indications, all the more in situations where radiation dose is a major problem (young patients, repeated exams, screening), it progressively emerges as a first line alternative for chest radiograph, providing more data at a similar radiation cost.

Diagnostic Performance of Ultra-Low-Dose Computed Tomography for Detecting Asbestos-Related Pleuropulmonary Diseases: Prospective Study in a Screening Setting

Objective

To evaluate the diagnostic performance of Ultra-Low-Dose Chest CT (ULD CT) for the detection of any asbestos-related lesions (primary endpoint) and specific asbestos-related abnormalities, i.e. non-calcified and calcified pleural plaques, diffuse pleural thickening, asbestosis and significant lung nodules (secondary endpoints).

Material and Methods

55 male patients (55.7±8.1 years old) with occupational asbestos exposure for at least 15 years and where CT screening was indicated were prospectively included. They all underwent a standard unenhanced chest CT (120kV, automated tube current modulation), considered as the reference, and an ULD CT (135kV, 10mA), both with iterative reconstruction.

Two chest radiologists independently and blindly read the examinations, following a detailed protocol. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy and error rate of ULD CT were calculated using the exact method of Pearson with a confidence interval of 95%.

Results

Radiation dose was 17.9±1.2mGy.cm (0.25mSv) for the ULD-CT versus 288.8 ±151mGy.cm (4mSv); p <2.2e^-16.

Prevalence of abnormalities was 20%. The ULD CT’s diagnostic performance in joint reading was high for the primary endpoint (sensitivity = 90.9%, specificity = 100%, positive predictive value = 100%, negative predictive value = 97.8%), high for lung nodules, diffuse pleural thickening and calcified pleural plaques (sensitivity, specificity, PPV and NPV = 100%) and fair for asbestosis (sensitivity = 75%, specificity = 100%, PPV = 00%, NPV = 98.1%).

Intra-reader accuracy between the ULD CT and the reference CT for the primary endpoint was 98% for the senior and 100% for the junior radiologist. Inter-reader agreement for the primary endpoint was almost perfect (Cohen’s Kappa of 0.81).

Conclusion

ULD CT in the screening of asbestos exposure related diseases has 90.9% sensitivity and 100% specificity, and could therefore be proposed as a first line examination.

Ultra-low-dose, low-dose, and standard-dose CT of the kidney, ureters, and bladder: is there a difference? Results from a systematic review of the literature

AIM

To investigate whether reducing the radiation dose of computed tomography (CT) of the kidney, ureters, and bladder (KUB) for acute renal colic impacts upon the specificity, sensitivity, and detection of urolithiasis.

MATERIALS AND METHODS

A systematic review of the literature over a 20-year period between 1995 and 2015 was conducted of all prospective studies in the English language reporting on adult patients who underwent CT KUB or non-contrast CT for renal colic or urolithiasis. Retrospective studies and those that included pregnant females, children, non-human test subjects, cadaveric use, and simulations were excluded. Data were collected using an Excel spreadsheet and ultra-low-dose (ULD CT) and low-dose CT KUB (LD CT) was defined as a radiation dose ≤1.9 and <3.5 mSv, respectively.

RESULTS

A total of 417 articles were identified, and after screening, seven articles (1,104 patients) were included in the present study with a male:female ratio of 3:2. Of the four studies with ULD CT for both males and females, the prevalence of urolithiasis ranged from 36% and 73%, with additional pathologies found in 12-15%. The effective radiation dose of ULD CT ranged from 0.5-1.9 mSv. Overall, ULD CT and LD CT had a sensitivity of 90-100% and a specificity of 86-100% across all studies.

CONCLUSIONS

ULD CT and LD CT are effective techniques and yield high sensitivity and specificity. Although they yield comparable results against standard-dose CT KUB in detecting alternative diagnoses, they may not be as effective in detecting stones <3 mm in size or in patients with a body mass index of >30 kg/m²; however, this should be the first-line investigation for the majority of renal colic patients in the modern era.

Radiologic Diagnosis of Asbestosis in Korea

Asbestosis is the most important change noted in the lung parenchyma after environmental and occupational exposure to asbestos fibers. It is characterized by diffuse interstitial pulmonary fibrosis. In Korea, the incidence of asbestosis will continue to increase for many years to come and the government enacted the Asbestos Damage Relief Law in 2011 to provide compensation to those suffering from asbestos-related diseases. Radiologic evaluation is necessary for diagnosis of asbestosis, and radiologists play a key role in this process. Therefore, it is important for radiologists to be aware of the various imaging features of asbestosis.

[Ultra-low dose chest CT: The end of chest radiograph?]

Ultra-low dose chest CT (ULD-CT) is acquired at a radiation dose lowered to that of a PA and lateral chest X-ray. Its image quality is degraded, yet remains diagnostic in many clinical indications. Technological improvements, with iterative reconstruction at the foreground, allowed a strong increase in the image quality obtained with this examination, which is achievable on most recent (<5 years) scanner. Established clinical indications of ULD-CT are increasing, and its non-inferiority compared to the reference "full dose" chest CT are currently demonstrated for the detection of solid nodules, for asbestos-related pleural diseases screening and for the monitoring of infectious pneumonia. Its current limitations are the obese patients (BMI>35) and the interstitial pneumonia, situations in which their performances are insufficient.

Medical imaging in occupational and environmental lung disease

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date summary of developments in medical imaging in the diagnosis, surveillance, treatment, and screening of occupational and environmental lung diseases, focusing on articles published within the past 2 years.

RECENT FINDINGS

Many new exposures resulting in lung disease have been described worldwide; medical imaging, particularly computed tomography (CT), is often pivotal in recognition and characterization of these new patterns of lung injury. Chest radiography remains important to surveillance studies tracking the long-term evolution of disease and effectiveness of air quality regulation. Finally, studies are proving the utility of screening with low-dose CT, and technical advances offer the prospect of further CT dose reduction with ultra-low-dose CT.

SUMMARY

In understanding the best practices and new developments in medical imaging, the occupational and environmental medicine clinician can optimize diagnosis and management of related lung diseases.

Lung cancer screening: Computed tomography or chest radiographs?

Worldwide, lung cancer is the leading cause of mortality due to malignancy. The vast majority of cases of lung cancer are smoking related and the most effective way of reducing lung cancer incidence and mortality is by smoking cessation. In the Western world, smoking cessation policies have met with limited success. The other major means of reducing lung cancer deaths is to diagnose cases at an earlier more treatable stage employing screening programmes using chest radiographs or low dose computed tomography. In many countries smoking is still on the increase, and the sheer scale of the problem limits the affordability of such screening programmes. This short review article will evaluate the current evidence and potential areas of research which may benefit policy making across the world.

CT brush and CancerZap!: two video games for computed tomography dose minimization

BACKGROUND

X-ray dose from computed tomography (CT) scanners has become a significant public health concern. All CT scanners spray x-ray photons across a patient, including those using compressive sensing algorithms. New technologies make it possible to aim x-ray beams where they are most needed to form a diagnostic or screening image. We have designed a computer game, CT Brush, that takes advantage of this new flexibility. It uses a standard MART algorithm (Multiplicative Algebraic Reconstruction Technique), but with a user defined dynamically selected subset of the rays. The image appears as the player moves the CT brush over an initially blank scene, with dose accumulating with every "mouse down" move. The goal is to find the "tumor" with as few moves (least dose) as possible.

RESULTS

We have successfully implemented CT Brush in Java and made it available publicly, requesting crowdsourced feedback on improving the open source code. With this experience, we also outline a "shoot 'em up game" CancerZap! for photon limited CT.

CONCLUSIONS

We anticipate that human computing games like these, analyzed by methods similar to those used to understand eye tracking, will lead to new object dependent CT algorithms that will require significantly less dose than object independent nonlinear and compressive sensing algorithms that depend on sprayed photons. Preliminary results suggest substantial dose reduction is achievable.