Patients from general practice with non-specific cancer symptoms: a retrospective study of symptoms and imaging.

BACKGROUND: Patients with non-specific symptoms or signs of cancer (NSSC) present a challenge as they are a heterogeneous population who are not candidates for fast-track work-up in an organ-specific cancer pre-planned pathway (CPP). Denmark has a cancer pre-planned pathway for this population (NSSC-CPP), but several issues remain unclarified, for example, distribution and significance of symptoms and findings, and choice of imaging. AIM: To investigate symptoms, cancer diagnoses, and diagnostic yield of computed tomography (CT) and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in patients on NSSC-CPP to improve the overall diagnostic process. DESIGN & SETTING: A retrospective medical chart review in a 1-year consecutive cohort (2020). METHOD: A total of 802 referrals were reviewed for diagnostic imaging in patients with NSSP from general practices, specialist practices, or the local hospital diagnostic centre responsible for NSSC-CPP. RESULTS: The study included 248 patients; 21% had cancer, most frequently gastrointestinal cancer (27%). The most frequent symptom was weight loss (56%). CT had a sensitivity of 85%, specificity of 87%, positive predictive value (PPV) of 65%, and negative predictive value (NPV) of 96%. For 18F-FDG-PET/CT, the numbers were sensitivity 82%, specificity 62%, PPV 33%, and NPV 94%. Patients frequently underwent subsequent examinations following initial imaging. CONCLUSION: The findings were in accordance with the literature. Patients with NSSC had a cancer prevalence of 21%, most frequently gastrointestinal. The most frequent symptom was weight loss and, even as the only symptom, it is a potential marker for cancer. CT and 18F-FDG-PET/CT were sensitive with high NPV, whereas PPV was superior in CT. Better stratification by symptoms or findings is an obvious focus point for future studies to further optimise the NSSC-CPP work-up strategy.

Potential for Dose Reduction in CT-Derived Left Ventricular Ejection Fraction: A Simulation Study.

BACKGROUND: Measuring left ventricular ejection fraction (LVEF) is important for detecting heart failure, e.g., in treatment with potentially cardiotoxic chemotherapy. MRI is considered the reference standard for LVEF, but availability may be limited and claustrophobia or metal implants still present challenges. CT has been shown to be accurate and would be advantageous, as LVEF could be measured in conjunction with routine chest-abdomen-pelvis oncology CT. However, the use of CT is not recommended due to the excessive radiation dose. This study aimed to explore the potential for dose reduction using simulation. Using an anthropomorphic heart phantom scanned at 13 dose levels, a noise simulation algorithm was developed to introduce controlled Poisson noise. Filtered backprojection parameters were iteratively tested to minimise differences in myocardium-to-ventricle contrast/noise ratio, as well as structural similarity index (SSIM) differences between real and simulated images at all dose levels. Fifty-one clinical CT coronary angiographies, scanned with full dose through end-systolic and -diastolic phases, were located retrospectively. Using the developed algorithm, noise was introduced corresponding to 25, 10, 5 and 2% of the original dose level. LVEF was measured using clinical software (Syngo.via VB50) with papillary muscles in and excluded from the LV volume. At each dose level, LVEF was compared to the 100% dose level, using Bland-Altman analysis. The effective dose was calculated from DLP using a conversion factor of 0.026 mSv/mGycm. RESULTS: In the clinical images, mean CTDIvol and DLP were 47.1 mGy and 771.9 mGycm, respectively (effective dose 20.0 mSv). Measurements with papillary muscles excluded did not exhibit statistically significant LVEF bias to full-dose images at 25, 10 and 5% simulated dose. At 2% dose, a significant bias of 4.4% was found. With papillary muscles included, small but significant biases were found at all simulated dose levels. CONCLUSION: Provided that measurements are performed with papillary muscles excluded from the LV volume, the dose can be reduced by a factor of 20 without significantly affecting LVEF measurements. This corresponds to an effective dose of 1 mSv. CT can potentially be used for LVEF measurement with minimal excessive radiation.

COMBINING HI-RESOLUTION SCAN MODE WITH DEEP LEARNING RECONSTRUCTION ALGORITHMS IN CARDIAC CT.

To investigate the impact of combining the high-resolution (Hi-res) scan mode with deep learning image reconstruction (DLIR) algorithm in CT. Two phantoms (Catphan600® and Lungman, small, medium, large size) were CT scanned using combinations of Hi-res/standard mode and high-definition (HD)/standard kernels. Images were reconstructed with ASiR-V and three levels of DLIR. Spatial resolution, noise and contrast-to-noise ratio (CNR) were assessed. The radiation dose was recorded. The spatial resolution increased using Hi-res & HD. Image noise in the Catphan600® (69%) and the Lungman (10-70%) significantly increased when Hi-res & HD was applied. DLIR reduced the mean noise (54%). The CNR was reduced (64%) for Hi-res & HD. The radiation dose increased for both small (+70%) and medium (+43%) Lungman phantoms but decreased slightly for the large ones (-3%) when Hi-res was applied. In conclusion, the Hi-res scan mode improved the spatial resolution. The HD kernel significantly increased the image noise. DLIR improved the image noise and CNR and did not affect the spatial resolution.

The impact of ASiR-V on abdominal CT radiation dose and image quality - A phantom study.

INTRODUCTION: To investigate how ASiR-V and kVp changes in Computed tomography (CT) affect radiation dose and image quality, when using automatic tube current modulation (ATCM) for different sized phantoms. METHODS: A liver-phantom with two different liver inserts (QRM, Moehrendorf, Germany), with extension rings, representing fat, were additionally applied to the phantom to simulate patients of different sizes (small: 30cm diameter, medium: 35cm and large: 40cm). Abdominal scans were performed on a 256 slice CT scanner (GE Healthcare, Milwaukee, WI, USA), with consistent pitch (0.992), rotation time (0.5s), slice thickness (0.625mm) and collimation (80mm), while other parameters were varied (kVp: 80/100/120/140; Noise Index: 13/22; mA interval 80-720, ASiR-V: 30/60/100%). CTDI and DLP was recorded for each scan and image quality was assessed using objective metrics in predefined anatomic areas (HU and noise). Radiation dose and image quality metrics were compared between protocols. RESULTS: CTDI decreased by 80% from ASIR-V 30% to ASiR-V 100% for prescribed NI 13, and by 79% for the prescribed NI of 22. For 100% ASiR-V and a prescribed NI of 22 the CTDI remained the same regardless of phantom size for the different kVp settings. Pairwise comparison revealed significant differences in CTDI (p < 0.0001) for all combinations of prescribed NI and ASIR-V levels, except the difference between ASIR-V levels of 30 and 60%, with a prescribed NI of 13 (p = 0.124). When data from the three phantom sizes were combined, increasing ASIR-V from 30-100%, resulted in noise decreases of 22% for NI of 13 and by 8% for NI of 22. Notably, image quality in the low contrast area of the liver insert was impaired when the large phantom was scanned with 100% ASiR-V and either 80/100kVp (NI 22), because of the large reduction in tube current applied (down to 80 mA). CONCLUSION: Substantial radiation dose reductions (up to 80%) resulted from increasing ASiR-V levels. However, image quality deteriorates when 100% ASiR-V is applied due to low applied tube current by the ATCM.

Coronary CT angiography-derived fractional flow reserve in-stable angina: association with recurrent chest pain.

AIMS: The aim of this study was to evaluate the association between coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFRCT) and recurrent chest pain (CP) at 1-year follow-up in patients with stable angina pectoris (SAP). METHODS AND RESULTS: Study of patients (n = 267) with SAP who underwent CCTA and FFRCT testing; 236 (88%) underwent invasive coronary angiography; and 87 (33%) were revascularized. Symptomatic status at 1-year follow-up was gathered by a structured interview. Three different FFRCT algorithms were applied using the following criteria for abnormality: (i) 2 cm-FFRCT ≤0.80; (ii) d-FFRCT ≤0.80; and (iii) a combination in which both a d-FFRCT ≤0.80 and a ΔFFRCT ≥0.06 must be present in the same vessel (c-FFRCT). Patients were classified into two groups based on the FFRCT test result and revascularization: completely revascularized/normal (CRN), patients in whom all coronary arteries with an abnormal FFRCT test result were revascularized or patients with completely normal FFRCT test results, and incompletely revascularized (IR), patients in whom ≥1 coronary artery with an abnormal FFRCT test result was not revascularized. Recurrent CP was present in 62 (23%) patients. Classification of patients (CRN or IR) was significantly associated with recurrent CP for all applied FFRCT interpretation algorithms. When applying the c-FFRCT algorithm, the association with recurrent CP was found, irrespective of the extent of coronary calcification and the degree of coronary stenosis. A negative association between per-patient minimal d-FFRCT and recurrent CP was demonstrated, P < 0.005. CONCLUSION: An abnormal FFRCT test result is associated with an increased risk of recurrent CP in patients with new-onset SAP.

COMPARISON OF CONVENTIONAL HAND EXAMINATION ON SIX OPTIMISED DR SYSTEMS.

The purpose of this study was to investigate the challenges in comparing digital radiography (DR) systems from different vendors for various combinations of exposure factors in posterior-anterior hand radiographs. Image quality was evaluated for a range of tube voltages and tube current-time products using a technical contrast-detail (CDRAD) phantom and an anthropomorphic hand phantom. 900 technical CDRAD images were analysed providing quality figures of merit (IQFinv) and two experienced reporting radiographers using visual grading analysis (VGA) scored 108 anthropomorphic images. This study demonstrates the differences between the DR systems included. When compensating for variations in dose, Canon showed superior results for technical image quality and Fuji for visual image quality for a standard dose point at DR hand examination (ln(DAP) 1.1, 50 kV and 2.5 mAs).

CAN SCATTER CORRECTION SOFTWARE REPLACE A GRID IN DR PELVIC EXAMINATIONS?

The purpose was to examine if scatter correction software could replace a grid while maintaining image quality and reducing radiation dose for pelvic DR examinations. Grid images was produced with 70 kV and 16mAs. Anthropomorphic- and Contrast Detail RADiography (CDRAD) non-grid images were produced with 60 kV, 80 kV and 90 kV combined with five different mAs and scatter correction software. The anthropomorphic images were analyzed by absolute Visual Grading Analysis (VGA). The CDRAD images were analyzed using the CDRAD analysis software. The results showed a total of 54.6% non-grid images were evaluated as unsuitable for diagnostic use by the VGA. The CDRAD grid images showed that the IQF_inv values were significantly different (p = 0.0001) when compared to every group of non-grid images. Hereby, the conclusion stated that the scatter correction software did not compensate for the loss in image quality due to scattered radiation at the exposure levels included in a pelvic examination.

CT triage for lung malignancy: coronal multiplanar reformation versus images in three orthogonal planes.

BACKGROUND: Generation of multiplanar reformation (MPR) images has become automatic on most modern computed tomography (CT) scanners, potentially increasing the workload of the reporting radiologists. It is not always clear if this increases diagnostic performance in all clinical tasks. PURPOSE: To assess detection performance using only coronal multiplanar reformations (MPR) when triaging patients for lung malignancies with CT compared to images in three orthogonal planes, and to evaluate performance comparison of novice and experienced readers. MATERIAL AND METHODS: Retrospective study of 63 patients with suspicion of lung cancer, scanned on 64-slice multidetector computed tomography (MDCT) with images reconstructed in three planes. Coronal images were presented to four readers, two novice and two experienced. Readers decided whether the patients were suspicious for malignant disease, and indicated their confidence on a five-point scale. Sensitivity and specificity on per-patient basis was calculated with regards to a reference standard of histological diagnosis, and compared with the original report using McNemar's test. Receiver operating characteristic (ROC) curves were plotted to compare the performance of the four readers, using the area under the curve (AUC) as figure of merit. RESULTS: No statistically significant difference of sensitivity and specificity was found for any of the readers when compared to the original reports. ROC analysis yielded AUCs in the range of 0.92-0.93 for all readers with no significant difference. Inter-rater agreement was substantial (kappa = 0.72). CONCLUSION: Sensitivity and specificity were comparable to diagnosis using images in three planes. No significant difference was found between experienced and novice readers.