ObjectivesTo compare radiologists’ performance reading CTs independently with their performance using radiographers as concurrent readers in lung cancer screening.Methods369 consecutive baseline CTs performed for the UK Lung Cancer Screening (UKLS) trial were double-read by radiologists reading either independently or concurrently with a radiographer. In concurrent reading, the radiologist reviewed radiographer-identified nodules and then detected any additional nodules. Radiologists recorded their independent and concurrent reading times. For each radiologist, sensitivity, average false-positive detections (FPs) per case and mean reading times for each method were calculated.Results694 nodules in 246/369 (66.7%) studies comprised the reference standard. Radiologists’ mean sensitivity and average FPs per case both increased with concurrent reading compared to independent reading (90.8 ± 5.6% vs. 77.5 ± 11.2%, and 0.60 ± 0.53 vs. 0.33 ± 0.20, respectively; p < 0.05 for 3/4 and 2/4 radiologists, respectively). The mean reading times per case decreased from 9.1 ± 2.3 min with independent reading to 7.2 ± 1.0 min with concurrent reading, decreasing significantly for 3/4 radiologists (p < 0.05).ConclusionsThe majority of radiologists demonstrated improved sensitivity, a small increase in FP detections and a statistically significantly reduced reading time using radiographers as concurrent readers.Key Points• Radiographers as concurrent readers could improve radiologists’ sensitivity in lung nodule detection. • An increase in false-positive detections with radiographer-assisted concurrent reading occurred. • The false-positive detection rate was still lower than reported for computer-aided detection. • Concurrent reading with radiographers was also faster than single reading. • The time saved per case using concurrently reading radiographers was relatively modest. Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-017-4903-z) contains supplementary material, which is available to authorized users.
ObjectiveHigh-pitch protocols are increasingly used in cardiovascular CT assessment for transcatheter aortic valve implantation (TAVI), but the impact on diagnostic image quality is not known.MethodsWe reviewed 95 consecutive TAVI studies: 44 (46%) high-pitch and 51 (54%) standard-pitch. Single high-pitch scans were performed regardless of heart rate. For standard-pitch acquisitions, a separate CT-aortogram and CT-coronary angiogram were performed with prospective gating, unless heart rate was ≥70 beats/min, when retrospective gating was used. The aortic root and coronary arteries were assessed for artefact (significant artefact=1; artefact not limiting diagnosis=2; no artefact=3). Aortic scans were considered diagnostic if the score was >1; the coronaries, if all three epicardial arteries scored >1.ResultsThere was no significant difference in diagnostic image quality for either the aorta (artefact-free high-pitch: 31 (73%) scans vs standard-pitch: 40 (79%), p=0.340) or the coronary tree as a whole (10 (23%) vs 15 (29%), p=0.493). However, proximal coronary arteries were less well visualised using high-pitch acquisitions (16 (36%) vs 30 (59%), p=0.04). The median (IQR) radiation dose was significantly lower in the high-pitch cohort (dose-length product: 347 (318–476) vs 1227 (1150–1474) mGy cm, respectively, p<0.001), and the protocol required almost half the amount of contrast.ConclusionsThe high-pitch protocol significantly reduces radiation and contrast doses and is non-inferior to standard-pitch acquisitions for aortic assessment. For aortic root assessment, the high-pitch protocol is recommended. However, if coronary assessment is critical, this should be followed by a conventional standard-pitch, low-dose, prospectively gated CT-coronary angiogram if the high-pitch scan is non-diagnostic.
Cardiovascular computed tomography (CCT) is a cutting-edge imaging technique providing important, non-invasive, diagnostic information. Concerns exist regarding radiation exposure to patient populations, but achieving optimal image quality at the lowest doses can be challenging. This guide provides practical advice about how quality can be assured in any CCT unit or radiology department. Illustrated by real-world vignettes and data analysis from our own experience, we highlight a multidisciplinary team approach to each stage of the patient journey, the effectiveness of regular dose audit overseen by a CT optimisation group, and the importance of underused systolic scanning techniques, in order to drive significant dose reduction without loss of image quality or clinical confidence.
PurposeTo evaluate image quality and diagnostic confidence of a raw-data-based iterative reconstruction technique (SAFIRE) in reduced-dose CCTA images in comparison with standard-dose filtered back projection (FBP) images.Materials and methods107 consecutive patients (72 males; 35 females), referred for a CCTA were prospectively included using a dual-source CT system in a high pitch (n = 51) or a sequential mode (n = 56) according to heart rate (mean DLP = 204.6 mGy.cm). From each acquisition, three series of images were reconstructed: standard-dose images reconstructed with FBP and considered as the reference standard (Group 1); and two series of reduced-dose images obtained with prototype software simulating a 30% dose reduction, and reconstructed with FBP (Group 2) or SAFIRE (Group 3). Two readers blindly evaluated each series for (a) objective noise and CNR; (b) coronary border sharpness, lesion severity; and (c) diagnostic confidence level using a 5-point scale.ResultsIn Group 2, there was a significant increase in noise compared to Group 1 (36.8 HU ±6.73 vs 30.4 HU ±5.20; p < 0.0001) and a CNR impairment (15.6 ± 4.3 vs 18.7 ± 4.5; p < 0.0001). In Group 3, despite the 30% dose reduction, SAFIRE restored the objective image quality: mean noise = 31.1 HU ±5.4 (p = 0.8) and CNR = 18.5 ± 5.0 (p = 0.7). However the diagnostic confidence was altered when compared with Group 1 (p < 0.0001), mainly rated as moderate with a blurred aspect of the coronary borders (81/107 [75.7%], p < 0.0001) and a significant number of artefactual non-flow-limiting soft plaques described in vessels considered as normal in Group 1 (105/428 [24.5%], p < 0.0001).ConclusionRaw-data-based iterative reconstruction allowed significant noise reduction but may be associated with blurring of the coronary luminal borders, which can decrease diagnostic confidence. When reporting reduced-dose CCTA with iterative reconstruction, false smooth plaque artefacts must be considered in diagnostic assessment and subsequent patient management.
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