Zsolt Szucs-Farkas

OBJECTIVE. The purpose of this article is to investigate the magnitude of dose optimization for a manufacturer-recommended urolithiasis protocol in a second-generation dual-source CT scanner. MATERIALS AND METHODS. Custom renal phantoms with 24 stones were scanned using the manufacturer-provided dual-energy CT protocol (tube A, 100 kVp and 210 reference mAs; tube B, 140 kVp and 162 reference mAs) and seven dose-optimized protocols in which the reference tube current–time product setting of tube A was reduced stepwise by 20 mAs. Detection and characterization of the stones was assessed. In the patient study, 25 patients underwent the manufacturer-provided dual-energy protocol and 25 patients underwent imaging with a dose-optimized protocol (tube A, 100 kVp and 90 reference mAs; tube B, 140 kVp and 70 reference mAs). Dose-length product (DLP), image noise, and contrast-to-noise ratio (CNR) were assessed. Subjective image quality was analyzed by three independent radiologists. RESULTS. In the phantom study, the reference tube current–time product of tube A could be reduced from 210 to 90 mAs without losing the accuracy of detection or characterization of the calculi. In the patient study, the dose-optimized protocol resulted in a significant reduction of the average DLP by 51% compared with the standard protocol (219.4 vs 443.5 mGy·cm, respectively; p = 0.0001). The image noise was higher, and the CNR was lower, in the dose-optimized group than in the standard-dose group (p < 0.05). The subjective overall image quality of the dose-optimized CT examinations was rated as good, and that of the standard-dose CT examinations was rated as excellent (p = 0.001). CONCLUSION. The in vitro and in vivo assessment revealed a potential for a 51% dose reduction of the manufacturer-recommended dual-energy CT protocol for urolithiasis without compromising the accuracy.

To study the effect of a nonlinear noise filter on the detection of simulated endoleaks in a phantom with 80- and 100-kVp multidetector computed tomographic (CT) angiography. An aortic aneurysm phantom, including iodinated endoleaks, was constructed. Multidetector CT angiography with use of 80-, 100-, and 120-kVp tube voltages was performed for simulated intermediate-sized and large patients (estimated body weights, 72-85 kg and 118-142 kg, respectively). Images obtained with 80 and 100 kVp were postprocessed by using a nonlinear noise filter. CT images containing 1152 endoleaks and images with no endoleaks were randomized and independently analyzed by three radiologists blinded to the location of the endoleaks. Diagnostic confidence and image quality were rated by using subjective scales. Analysis of variance was used for statistical assessment. In simulated intermediate-sized patients, energy reduction from 120 to 100 kVp and from100 to 80 kVp did not decrease image quality when images with reduced kilovoltage were filtered (P = .2692 and P > .99, respectively). Readers detected more endoleaks on the filtered 100-kVp images than on the nonfiltered images in simulated large patients (83 vs 75 lesions, P = .041). The number of detected endoleaks and the confidence rate were similar at 100 kVp with a filter and at 120 kVp in simulated large patients (P = .339 and P = .211, respectively). In a phantom, the nonlinear noise filter can prevent decreased image quality with use of 80- and 100-kVp abdominal multidetector CT angiography at a wide range of simulated body weights and may facilitate a better detection rate of endoleaks in heavy patients.

OBJECTIVE. The objective of our study was to compare the performance of low-dose linear slit digital radiography (DR) with computed radiography (CR) for the detection of trauma sequelae in the chest including rib fractures, pneumothorax, and lung contusion.MATERIALS AND METHODS. Eighty trauma victims (62 males, 18 females; mean age, 51.5 years) with a total of 612 rib fractures and 80 consecutive patients without rib fractures (59 males, 21 females; mean age, 39.5 years) were retrospectively analyzed. All patients had undergone whole-body linear slit DR and consecutive chest CT, and 87 patients underwent follow-up CR of the chest within 24 hours of DR and CT. Four blinded readers assessed image quality, rib fracture localization with diagnostic confidence, and the presence of pneumothorax and lung contusion on linear slit DR and CR images. Sensitivity for rib fractures and image quality were compared using the Wilcoxon's test. For the detection of pneumothorax and lung contusion, the difference in the are...

The detection rate of pulmonary emboli (PE) with computed tomography angiography (CTA) using either a standard or a low-dose protocol, combining reduced radiation exposure and iodine delivery rate, was retrospectively analyzed in a matched cohort of 120 patients

To retrospectively analyze the performance of a commercial computer-aided diagnosis (CAD) software in the detection of pulmonary nodules in original and energy-subtracted (ES) chest radiographs. Original and ES chest radiographs of 58 patients with 105 pulmonary nodules measuring 5–30 mm and images of 25 control subjects with no nodules were randomized. Five blinded readers evaluated firstly the original postero-anterior images alone and then together with the subtracted radiographs. In a second phase, original and ES images were analyzed by a commercial CAD program. CT was used as reference standard. CAD results were compared to the readers’ findings. True-positive (TP) and false-positive (FP) findings with CAD on subtracted and non-subtracted images were compared. Depending on the reader’s experience, CAD detected between 11 and 21 nodules missed by readers. Human observers found three to 16 lesions missed by the CAD software. CAD used with ES images produced significantly fewer FPs than with non-subtracted images: 1.75 and 2.14 FPs per image, respectively (p = 0.029). The difference for the TP nodules was not significant (40 nodules on ES images and 34 lesions in non-subtracted radiographs, p = 0.142). CAD can improve lesion detection both on energy subtracted and non-subtracted chest images, especially for less experienced readers. The CAD program marked less FPs on energy-subtracted images than on original chest radiographs.

OBJECTIVE. In this experimental study we assessed the diagnostic performance of digital linear slit scanning radiography compared with computed radiography (CR) for the detection of urinary calculi in an anthropomorphic phantom imitating patients weighing approximately 58–88 kg. CONCLUSION. Compared with CR, linear slit scanning radiography is superior for the detection of urinary stones and may be used for pretreatment localization and follow-up at a lower patient exposure.

The purpose of this retrospective study was to intra-individually compare the image quality of computed radiography (CR) and low-dose linear-slit digital radiography (LSDR) for supine chest radiographs. A total of 90 patients (28 female, 62 male; mean age, 55.1 years) imaged with CR and LSDR within a mean time interval of 2.8 days ± 3.0 were included in this study. Two independent readers evaluated the image quality of CR and LSDR based on modified European Guidelines for Quality Criteria for chest X-ray. The Wilcoxon test was used to analyse differences between the techniques. The overall image quality of LSDR was significantly better than the quality of CR (9.75 vs 8.16 of a maximum score of 10; p < 0.001). LSDR performed significantly better than CR for delineation of anatomical structures in the mediastinum and the retrocardiac lung (p < 0.001). CR was superior to LSDR for visually sharp delineation of the lung vessels and the thin linear structures in the lungs. We conclude that LSDR yields better image quality and may be more suitable for excluding significant pathological features of the chest in areas with high attenuation compared with CR.