Optimising CT‐chest protocols and the added value of venous‐phase contrast timing; Observational case‐control

Abstract

Introduction To optimize CT chest protocol by comparing venous contrast timing with arterial timing for contrast opacification in vessels, qualitative image quality and radiologists’ satisfaction and diagnostic confidence in assessing for potential nodal, pleural and pulmonary disease in general oncology outpatients. Method Matched case−control study performed following CT protocol update. 92 patients with a range of primary malignancies with 2 CT chests in a 2‐year period, one with an arterial phase protocol and the second in the 60 second venous phase, were included. Contrast attenuation in aorta, pulmonary artery and liver were measured. Subjective measurements assessed perivenous artefact, confidence in nodal pleural and pulmonary assessment and presence of pulmonary emboli. Statistical analysis was performed using paired and unpaired t‐tests. Results Venous‐phase CT demonstrated more consistent enhancement of the vessels, with higher attenuation of the nodes, pulmonary and pleural lesions. There was a significant reduction in perivenous beam hardening artefact on venous‐phase CT (P < 0.001). Diagnostic confidence was significantly higher for nodal assessment and pleural abnormality visibility (P < 0.001) and pleural assessment (P < 0.05). There was no significant difference in pulmonary mass visibility. There was adequate enhancement to diagnose significant pulmonary emboli (PE) with 4 incidental PEs detected on the venous phase, extending to segmental vessels. Conclusion Venous‐phase CT chest performs better than arterial‐phase on all fronts, without compromising assessment of incidental pulmonary emboli. When intravenous contrast is indicated in a routine chest CT (excluding a CT‐angiogram), the default timing should be a venous or 60s phase.

Comparison of epicardial adipose tissue volume quantification between ECG-gated cardiac and non-ECG-gated chest computed tomography scans

“…The venous-phase enhanced chest CT images have been reported to have incremental value over arterial-phase enhancement for diagnostic purpose [ 40 ] and are increasingly acquired in clinical practice. However, the difference in EAT volume quantification between the venous-phase enhancement and the conventional arterial-phase enhancement has never been explored.…”

Assessment of a single‐pass venous phase CT chest, abdomen and pelvis and dual‐energy CT in general oncology outpatients

“…17 The venous phase in the chest allows time for pleural and pulmonary soft tissue masses and lymph nodes to enhance, with an additional reduction of perivenous artefact from the SVC and ascending aorta which can obscure mediastinal lymph nodes. [3][4][5][6][7] It is beneficial for assessing mesothelioma, pleural and chest wall metastases and complex effusions. [18][19][20] Our study demonstrated a significant increase in the visualisation of pleural masses on vCAP by Reader 1, with a trend to more clearly seen mediastinal nodes.…”

“…However, other publications have shown that the detection of incidental PE may be adequate in a venous chest protocol. [4][5][6][7] Due to the confirmed benefits of the vCAP protocol, following this study, we made this the default protocol across our network for all CT CAP studies for oncology and non-oncology indications and a venous phase CT chest for all non-angiographic postcontrast CT chests. The use of DECT in a subset of patients showed a statistically significant increase in the conspicuity of sub-centimetre and larger liver lesions by both readers.…”

“…There is evidence that a venous phase CT chest provides improved assessment in oncology, with a reduction of streak artefact from superior vena cava (SVC) contrast in the mediastinum, and improved enhancement of pleural and pulmonary masses and mediastinal lymph nodes. [3][4][5][6][7] The combination of a venous CT chest with portal venous CT abdomen and pelvis, allowing for an additional arterial upper abdomen only when required, is of likely benefit in oncological imaging, with optimised visualisation of tumours and lymph nodes in the chest and a reduction in radiation dose by avoiding unnecessary double imaging of the upper abdomen. While it is used in some centres, there is a paucity of literature regarding the comparative performance and optimal timing of a single-pass technique in general oncology imaging.…”

“…The traditional protocol for a contrast‐enhanced CT CAP in many departments in Australia and New Zealand is an arterial phase scan of the chest including all or part of the liver, followed by a portal venous phase scan from the diaphragm to the pubic symphysis. There is evidence that a venous phase CT chest provides improved assessment in oncology, with a reduction of streak artefact from superior vena cava (SVC) contrast in the mediastinum, and improved enhancement of pleural and pulmonary masses and mediastinal lymph nodes 3–7 …”