Tube Voltage, DNA Double-Strand Breaks, and Image Quality in Coronary CT Angiography

Deep learning reconstruction allows for usage of contrast agent of lower concentration for coronary CTA than filtered back projection and hybrid iterative reconstruction

BACKGROUND

The demand for homogeneous and higher vascular contrast enhancement is critical to provide an appropriate interpretation of abnormal vascular findings in coronary computed tomography angiography (CTA).

PURPOSE

To evaluate the effect of various contrast media concentrations (Iohexol-370, Iohexol-300, Iohexol-240) and image reconstructions (filtered back projection [FBP], hybrid iterative reconstruction [IR], and deep learning reconstruction [DLR]) on coronary CTA.

MATERIAL AND METHODS

A total of 63 patients referred for coronary CTA between July and October 2021 were enrolled in this prospective study, and they randomly received one of three contrast media. CTA images were reconstructed with FBP, hybrid IR, and DLR. The CT attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated for all three images. The images were subjectively evaluated by two radiologists in terms of overall image quality, artifacts, image noise, and vessel wall delineation on a 5-point Likert scale.

RESULTS

The application of DLR resulted in significantly lower image noise; higher CT attenuation, SNR, and CNR; and better subjective analysis among the three different concentrations of contrast media groups (P < 0.001). There was no significant difference in the CT attenuation of the left ventricle (P = 0.089) and coronary arteries (P = 0.072) between hybrid IR at Iohexol-300 and DLR at Iohexol-240. Furthermore, application of DLR to the Iohexol-240 significantly improved SNR and CNR; it achieved higher subjective scores compared with hybrid IR at Iohexol-300 (P < 0.001).

CONCLUSION

We suggest that using DLR with Iohexol-240 contrast media is preferable to hybrid IR with Iohexol-300 contrast media in coronary CTA.

Does this patient have COVID-19? A practical guide for the internist

Coronavirus disease 2019 (COVID-19) is currently causing a pandemic and will likely persist in endemic form in the foreseeable future. Physicians need to correctly approach this new disease, often representing a challenge in terms of differential diagnosis. Although COVID-19 lacks specific signs and symptoms, we believe internists should develop specific skills to recognize the disease, learning its 'semeiotic'. In this review article, we summarize the key clinical features that may guide in differentiating a COVID-19 case, requiring specific testing, from upper respiratory and/or influenza-like illnesses of other aetiology. We consider two different clinical settings, where availability of the different diagnostic strategies differs widely: outpatient and inpatient. Our reasoning highlights how challenging a balanced approach to a patient with fever and flu-like symptoms can be. At present, clinical workup of COVID-19 remains a hard task to accomplish. However, knowledge of the natural history of the disease may aid the internist in putting common and unspecific symptoms into the correct clinical context.