Optimising whole body computed tomography doses for paediatric trauma patients: a Swiss retrospective analysis.

We aimed to evaluate the impact of a low-dose whole-body computed tomography (WBCT) protocol on radiation doses in paediatric major trauma patients. Retrospective cohort study of paediatric trauma patients (<16 years) at a national level 1 paediatric trauma centre (PTC) over a 6 year period prior and post introduction of a low-dose WBCT protocol (2014-2019). Demographic data, patient characteristics, CT device, and exposure information including scan range, dose-length product, and volume CT dose index were collected. Effective dose (ED) and exposure parameters were compared before and after protocol introduction. Forty-eight patients underwent WBCT during the study period. Prior to introduction of the low-dose protocol (n= 18), the ED was 20.6 mSv (median 20.1 ± 5.3 mSv [range 12.5-30.7]). After introduction of the low-dose WBCT protocol (n= 30), mean ED was 4.8 mSv (median 2.6 ± 5.0 [range: 0.8-19.1]). This resulted in a reduction of 77% in mean ED (pvalue <0.001). Significant radiation dose reduction of 77% can be achieved with low-dose WBCT protocols in PTCs.

Impact of the incorrect use of lead drapes on staff and patient doses in interventional radiology.

To evaluate the usefulness of commercially available scatter reduction drapes in mitigating staff exposure in interventional radiology and the potential harmful effects of drape malpositioning in terms of exposure levels to both patients and staff. An anthropomorphic phantom was irradiated on an angiography device under three scenarios: no drape and correct and incorrect drape positioning. Different levels of incorrect drape positioning relative to the field-of-view (FOV) were evaluated: slight, mild and severe. Real-time dosimeter systems (positioned on the operator's eye, chest and thyroid) were used to evaluate accumulative doses and dose rates. Different obstruction levels were evaluated and compared to the observer's perception. Additionally, patient exposure was evaluated for all scenarios using a dose area product (DAP). Up to a mild obstruction, by using the drape a dose reduction of up to 86% was obtained while a severe obstruction produced a 1000% increase in exposure, respectively for all dosimeter positions compared to the use of no drape. A similar order of magnitude was observed for patient exposure. Good agreement was obtained for the observer perception of the FOV obstruction up to 25% of the FOV; for larger obstructions, an overestimate of the obstruction was observed. Patient lead drapes can reduce staff doses in interventional radiology procedures even when mildly malpositioned and obscuring the FOV. Special attention to protective drape positioning is necessary, since the severe obstruction of the FOV results in a large increase in both operator and patient exposure.

Minimum perceivable size difference: how well can radiologists visually detect a change in lung nodule size from CT images?

OBJECTIVE: The purpose of this study was to determine how well radiologists could visually detect a change in lung nodule size on the basis of visual image perception alone. SUBJECTS AND METHODS: Under IRB approval, 109 standard chest CT image series were anonymized and exported from PACS. Nine hundred forty virtual lung nodule pairs (six baseline diameters, six relative volume differences, two nodule types-solid and ground glass-and 14 repeats) were digitally inserted into the chest CT image series (same location, different sizes between the pair). These digitally altered CT image pairs were shown to nine radiologists who were tasked to visually determine which image contained the larger nodule using a two-alternative forced-choice perception experimental design. These data were statistically analyzed using a generalized linear mixed effects model to determine how accurately the radiologists were able to correctly identify the larger nodule. RESULTS: Nominal baseline nodule diameter, relative volume difference, and nodule type were found to be statistically significant factors (p < 0.001) in influencing the radiologists' accuracy. For solid (ground-glass) nodules, the baseline diameter needed to be at least 6.3 mm (13.2 mm) to be able to visually detect a 25% change in volume with 95 ± 1.4% accuracy. Accuracy was lowest for the nodules with the smallest baseline diameters and smallest relative volume differences. Additionally, accuracy was lower for ground-glass nodules compared to solid nodules. CONCLUSIONS: Factors that impacted visual size assessment were baseline nodule diameter, relative volume difference, and solid versus non-solid nodule type, with larger and more solid lesions offering a more precise assessment of change. KEY POINTS: • For solid nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 6.3-mm baseline diameter. • For ground-glass nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 13.2-mm baseline diameter. • Accuracy in detecting a change in nodule size began to stabilize around 90-100% for nodules with larger baseline diameters (> 8 mm for solid nodules, > 12 mm for ground-glass nodules) and larger relative volume differences (>15% for solid nodules, > 25% for ground-glass nodules).

Osteoid osteoma: multimodality imaging with focus on hybrid imaging.

Osteoid osteoma is a painful, benign, osteoblastic lesion that occurs in younger patients and affects the extremities or the axial skeleton. While plain film findings may suggest the diagnosis, in complex anatomical regions such as the spine, pelvis, wrist and foot advanced imaging modalities are often required. A typical nidus surrounded by sclerosis or cortical thickening characterizes osteoid osteoma on plain radiography and CT. MR is the cross-sectional imaging modality of choice for most musculoskeletal disorders. Unfortunately, extensive accompanying bone marrow oedema, soft-tissue alterations, difficulty detecting the nidus, and lesion locations close to a joint (with reactive arthritis) may make a confident diagnosis of osteoid osteoma by MR imaging difficult. Hybrid imaging with bone-seeking tracers such as SPECT/CT with 99mTc-labelled bisphosphonates or PET/CT with 18F-labelled sodium fluoride (18F-NaF) combines high radionuclide uptake with morphological details and provides accurate diagnosis of osteoid osteoma and additional information for treatment planning. FDG is not the recommended PET tracer because osteoid osteoma is normally FDG-negative, although some osteoid osteomas may show increased FDG uptake. Osteoblastoma, Brodie's abscess and stress fractures may mimic osteoid osteoma on imaging and clinical presentation. Once identified as the pain generator, destruction of the osteoid osteoma nidus by ablation or resection techniques usually leads to complete healing. Image-guided drill excision and radiofrequency ablation are widely used interventions. We review the presentation of osteoid osteoma across all imaging modalities, with special focus on hybrid imaging techniques.

Multireader Determination of Clinically Significant Obstruction Using Hyperpolarized 129Xe-Ventilation MRI.

OBJECTIVE: The objective of our study was to identify the magnitude and distribution of ventilation defect scores (VDSs) derived from hyperpolarized (HP) 129Xe-MRI associated with clinically relevant airway obstruction. MATERIALS AND METHODS: From 2012 to 2015, 76 subjects underwent HP 129Xe-MRI (48 healthy volunteers [mean age ± SD, 54 ± 17 years]; 20 patients with asthma [mean age, 44 ± 20 years]; eight patients with chronic obstructive pulmonary disease [mean age, 67 ± 5 years]). All subjects underwent spirometry 1 day before MRI to establish the presence of airway obstruction (forced expiratory volume in 1 second-to-forced vital capacity ratio [FEV1/FVC] < 70%). Five blinded readers assessed the degree of ventilation impairment and assigned a VDS (range, 0-100%). Interreader agreement was assessed using the Fleiss kappa statistic. Using FEV1/FVC as the reference standard, the optimum VDS threshold for the detection of airway obstruction was estimated using ROC curve analysis with 10-fold cross-validation. RESULTS: Compared with the VDSs in healthy subjects, VDSs in patients with airway obstruction were significantly higher (p < 0.0001) and significantly correlated with disease severity (r = 0.66, p < 0.0001). Ventilation defects in subjects with airway obstruction did not show a location-specific pattern (p = 0.158); however, defects in healthy control subjects were more prevalent in the upper lungs (p = 0.014). ROC curve analysis yielded an optimal threshold of 12.4% ± 6.1% (mean ± SD) for clinically significant VDS. Interreader agreement for 129Xe-MRI was substantial (κ = 0.71). CONCLUSION: This multireader study of a diverse cohort of patients and control subjects suggests a 129Xe-ventilation MRI VDS of 12.4% or greater represents clinically significant obstruction.

Single-breath clinical imaging of hyperpolarized (129)Xe in the airspaces, barrier, and red blood cells using an interleaved 3D radial 1-point Dixon acquisition.

PURPOSE: We sought to develop and test a clinically feasible 1-point Dixon, three-dimensional (3D) radial acquisition strategy to create isotropic 3D MR images of (129)Xe in the airspaces, barrier, and red blood cells (RBCs) in a single breath. The approach was evaluated in healthy volunteers and subjects with idiopathic pulmonary fibrosis (IPF). METHODS: A calibration scan determined the echo time at which (129)Xe in RBCs and barrier were 90° out of phase. At this TE, interleaved dissolved and gas-phase images were acquired using a 3D radial acquisition and were reconstructed separately using the NUFFT algorithm. The dissolved-phase image was phase-shifted to cast RBC and barrier signal into the real and imaginary channels such that the image-derived RBC:barrier ratio matched that from spectroscopy. The RBC and barrier images were further corrected for regional field inhomogeneity using a phase map created from the gas-phase (129)Xe image. RESULTS: Healthy volunteers exhibited largely uniform (129)Xe-barrier and (129)Xe-RBC images. By contrast, (129)Xe-RBC images in IPF subjects exhibited significant signal voids. These voids correlated qualitatively with regions of fibrosis visible on CT. CONCLUSIONS: This study illustrates the feasibility of acquiring single-breath, 3D isotropic images of (129)Xe in the airspaces, barrier, and RBCs using a 1-point Dixon 3D radial acquisition.

Maximum-Intensity-Projection and Computer-Aided-Detection Algorithms as Stand-Alone Reader Devices in Lung Cancer Screening Using Different Dose Levels and Reconstruction Kernels.

OBJECTIVE: The objective of our study was to evaluate lung nodule detection rates on standard and microdose chest CT with two different computer-aided detection systems (SyngoCT-CAD, VA 20, Siemens Healthcare [CAD1]; Lung CAD, IntelliSpace Portal DX Server, Philips Healthcare [CAD2]) as well as maximum-intensity-projection (MIP) images. We also assessed the impact of different reconstruction kernels. MATERIALS AND METHODS: Standard and microdose CT using three reconstruction kernels (i30, i50, i70) was performed with an anthropomorphic chest phantom. We placed 133 ground-glass and 133 solid nodules (diameters of 5 mm, 8 mm, 10 mm, and 12 mm) in 55 phantoms. Four blinded readers evaluated the MIP images; one recorded the results of CAD1 and CAD2. Sensitivities for CAD and MIP nodule detection on standard dose and microdose CT were calculated for each reconstruction kernel. RESULTS: Dose for microdose CT was significantly less than that for standard-dose CT (0.1323 mSv vs 1.65 mSv; p < 0.0001). CAD1 delivered superior results compared with CAD2 for standard-dose and microdose CT (p < 0.0001). At microdose level, the best stand-alone sensitivity (97.6%) was comparable with CAD1 sensitivity (96.0%; p = 0.36; both with i30 reconstruction kernel). Pooled sensitivities for all nodules, doses, and reconstruction kernels on CAD1 ranged from 88.9% to 97.3% versus 49.6% to 73.9% for CAD2. The best sensitivity was achieved with standard-dose CT, i50 kernel, and CAD1 (97.3%) versus 96% with microdose CT, i30 or i50 kernel, and CAD1. MIP images and CAD1 had similar performance at both dose levels (p = 0.1313 and p = 0.48). CONCLUSION: Submillisievert CT is feasible for detecting solid and ground-glass nodules that require soft-tissue kernels for MIP and CAD systems to achieve acceptable sensitivities. MIP reconstructions remain a valuable adjunct to the interpretation of chest CT for increasing sensitivity and have the advantage of significantly lower false-positive rates.

Characterizing search, recognition, and decision in the detection of lung nodules on CT scans: elucidation with eye tracking.

PURPOSE: To determine the effectiveness of radiologists' search, recognition, and acceptance of lung nodules on computed tomographic (CT) images by using eye tracking. MATERIALS AND METHODS: This study was performed with a protocol approved by the institutional review board. All study subjects provided informed consent, and all private health information was protected in accordance with HIPAA. A remote eye tracker was used to record time-varying gaze paths while 13 radiologists interpreted 40 lung CT images with an average of 3.9 synthetic nodules (5-mm diameter) embedded randomly in the lung parenchyma. The radiologists' gaze volumes ( GV gaze volume s) were defined as the portion of the lung parenchyma within 50 pixels (approximately 3 cm) of all gaze points. The fraction of the total lung volume encompassed within the GV gaze volume s, the fraction of lung nodules encompassed within each GV gaze volume (search effectiveness), the fraction of lung nodules within the GV gaze volume detected by the reader (recognition-acceptance effectiveness), and overall sensitivity of lung nodule detection were measured. RESULTS: Detected nodules were within 50 pixels of the nearest gaze point for 990 of 992 correct detections. On average, radiologists searched 26.7% of the lung parenchyma in 3 minutes and 16 seconds and encompassed between 86 and 143 of 157 nodules within their GV gaze volume s. Once encompassed within their GV gaze volume , the average sensitivity of nodule recognition and acceptance ranged from 47 of 100 nodules to 103 of 124 nodules (sensitivity, 0.47-0.82). Overall sensitivity ranged from 47 to 114 of 157 nodules (sensitivity, 0.30-0.73) and showed moderate correlation (r = 0.62, P = .02) with the fraction of lung volume searched. CONCLUSION: Relationships between reader search, recognition and acceptance, and overall lung nodule detection rate can be studied with eye tracking. Radiologists appear to actively search less than half of the lung parenchyma, with substantial interreader variation in volume searched, fraction of nodules included within the search volume, sensitivity for nodules within the search volume, and overall detection rate.

Suction/Inspiration against resistance or standardized Mueller maneuver : a new breathing technique to improve contrast density within the pulmonary artery: a pilot CT study.

OBJECTIVE: Our aim was to prospectively investigate whether the recently introduced suction/inspiration against resistance breathing method leads to higher computed tomography (CT) contrast density in the pulmonary artery compared to standard breathing. MATERIAL AND METHODS: The present study was approved by the Medical Ethics committee and all subjects gave written informed consent. Fifteen patients, each without suspicious lung emboli, were randomly assigned to four different groups with different breathing maneuvers (suction against resistance, Valsalva, inspiration, expiration) during routine CT. Contrast enhancement in the central and peripheral sections of the pulmonary artery were measured and compared with one another. RESULTS: Peripheral enhancement during suction yielded increased mean densities of 138.14 Hounsfield units (HU) (p = 0.001), compared to Valsalva and a mean density of 67.97 HU superior to inspiration (p = 0.075). Finally, suction in comparison to expiration resulted in a mean increase of 30.51 HU (p = 0.42). Central parts of pulmonary arteries presented significantly increased enhancement values (95.74 HU) for suction versus the Valsalva technique (p = 0.020), while all other mean densities were in favour of suction (versus inspiration: p = 0.201; versus expiration: p = 0.790) without reaching significance. CONCLUSION: Suction/Inspiration against resistance is a promising technique to improve contrast density within pulmonary vessels, especially in the peripheral parts, in comparison to other breathing maneuvers. KEY POINTS: • Suction/Inspiration against resistance is promising to improve contrast density within the pulmonary artery. • Patients potentially suffering pulmonary embolism are able to follow suction/inspiration against resistance. • Contrast density after suction is superior in comparison to other breathing maneuvers.

Lung nodule detection by microdose CT versus chest radiography (standard and dual-energy subtracted).

OBJECTIVE: The purpose of this study was to investigate the feasibility of microdose CT using a comparable dose as for conventional chest radiographs in two planes including dual-energy subtraction for lung nodule assessment. MATERIALS AND METHODS: We investigated 65 chest phantoms with 141 lung nodules, using an anthropomorphic chest phantom with artificial lung nodules. Microdose CT parameters were 80 kV and 6 mAs, with pitch of 2.2. Iterative reconstruction algorithms and an integrated circuit detector system (Stellar, Siemens Healthcare) were applied for maximum dose reduction. Maximum intensity projections (MIPs) were reconstructed. Chest radiographs were acquired in two projections with bone suppression. Four blinded radiologists interpreted the images in random order. RESULTS: A soft-tissue CT kernel (I30f) delivered better sensitivities in a pilot study than a hard kernel (I70f), with respective mean (SD) sensitivities of 91.1%±2.2% versus 85.6%±5.6% (p=0.041). Nodule size was measured accurately for all kernels. Mean clustered nodule sensitivity with chest radiography was 45.7%±8.1% (with bone suppression, 46.1%±8%; p=0.94); for microdose CT, nodule sensitivity was 83.6%±9% without MIP (with additional MIP, 92.5%±6%; p<10(-3)). Individual sensitivities of microdose CT for readers 1, 2, 3, and 4 were 84.3%, 90.7%, 68.6%, and 45.0%, respectively. Sensitivities with chest radiography for readers 1, 2, 3, and 4 were 42.9%, 58.6%, 36.4%, and 90.7%, respectively. In the per-phantom analysis, respective sensitivities of microdose CT versus chest radiography were 96.2% and 75% (p<10(-6)). The effective dose for chest radiography including dual-energy subtraction was 0.242 mSv; for microdose CT, the applied dose was 0.1323 mSv. CONCLUSION: Microdose CT is better than the combination of chest radiography and dual-energy subtraction for the detection of solid nodules between 5 and 12 mm at a lower dose level of 0.13 mSv. Soft-tissue kernels allow better sensitivities. These preliminary results indicate that microdose CT has the potential to replace conventional chest radiography for lung nodule detection.

Effects of model-based iterative reconstruction on image quality for low-dose computed tomographic angiography of the thoracic aorta in a Swine model.

PURPOSE: The aim of the study was to assess the image quality of multi-detector-row computed tomography (CT) angiographic images of the thoracic aorta reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction, and model-based iterative reconstruction (MBIR) at different kVp and mA settings. METHODS: A healthy 56.1-kg Yorkshire pig underwent sequential arterial CT angiograms on a 64-slice multi-detector-row CT scanner (Discovery CT 750HD; GE Healthcare Inc, Milwaukee, Wis) at progressively lower kVp and mA settings. At 120-, 100-, and 80-kVp levels, the pig was scanned at 700, 400, 200, 100, and 50 mA at, for a total of 15 scans. Each scan was reconstructed with FBP, adaptive statistical iterative reconstruction (50% blend), and MBIR. Relative noise and contrast-to-noise ratio (CNR) were calculated from regions of interest over the aorta and paraspinous muscle. In addition, selected axial and oblique sagittal images were scored subjectively for both aortic wall visibility and for overall image quality. RESULTS: Averaged across all kVp and mA variations, MBIR reduced relative noise by 73.9% and improved CNR by 227% compared with FBP; MBIR reduced relative noise by 63.4% and improved CNR by 107% compared with ASIR. The effects were more pronounced in lower tube output settings. At 100 kVp/700 mA, MBIR reduced noise by 57% compared with FBP and 40% compared with ASIR. At 100 kVp/50 mA, MBIR reduced noise by 82% compared with FBP and 75% compared with ASIR. Subjective improvements in image quality were noted only in higher noise settings. CONCLUSIONS: Model-based iterative reconstruction reduces relative noise and improves CNR compared with ASIR and FBP at all kVp and mA settings, which were significantly greater at lower mA settings.

Suction against resistance: a new breathing technique to significantly improve the blood flow ratio of the superior and inferior vena cava.

OBJECTIVES: Optimal contrast within the pulmonary artery is achieved by the maximum amount of contrast-enhanced blood flowing through the superior vena cava (SVC), while minimum amounts of non-contrasted blood should originate from the inferior vena cava (IVC). This study aims to clarify whether "suction against resistance" might optimise this ratio. METHODS: Phase-contrast pulse sequences on a 1.5T MRI magnet were used for flow quantification (mean flow (mL/s), stroke volume (Vol) in the SVC and IVC in volunteers. Different breathing manoeuvers were analysed repeatedly: free breathing; inspiration; expiration; suction against resistance, and Valsalva. To standardise breathing commands, volunteers performed suction and Valsalva manoeuvers with an MR-compatible manometer. RESULTS: Suction against resistance was associated with a significant drop of the IVC/SVC flow quotient (1.63 [range 1.3-2.0] p < 0.05 at -10 mmHg and 1.48 [1.1-1.9] p < 0.01 at -20 mmHg) corresponding to increased blood flow from SVC and diminished flow originating from the IVC. The remaining breathing commands (free breathing 2.2; inspiration 2.4; expiration 2.4; Valsalva 10 mmHg 2.3; Valsalva 20 mmHg 2.6; and Valsalva 30 mmHg 2.2) showed no differences (p > 0.05). CONCLUSIONS: Suction against resistance caused a significant drop in the IVC/SVC quotient. Theoretically, this breathing manoeuver might significantly improve the enhancement characteristics of CT angiography. KEY POINTS: Suction provokes reduction in blood flow in the inferior vena cava. Ratio between the inferior and superior vena cava blood flow diminished during suction. Manometer used during breathing standardises MR phase-contrast blood flow measurements.

Impact of image quality, radiologists, lung segments, and Gunnar eyewear on detectability of lung nodules in chest CT.

BACKGROUND: Despite the increasingly higher spatial and contrast resolution of CT, nodular lesions are prone to be missed on chest CT. Tinted lenses increase visual acuity and contrast sensitivity by filtering short wavelength light of solar and artificial origin. PURPOSE: To test the impact of Gunnar eyewear, image quality (standard versus low dose CT) and nodule location on detectability of lung nodules in CT and to compare their individual influence. MATERIAL AND METHODS: A pre-existing database of CT images of patients with lung nodules >5 mm, scanned with standard does image quality (150 ref mAs/120 kVp) and lower dose/quality (40 ref mAs/120 kVp), was used. Five radiologists read 60 chest CTs twice: once with Gunnar glasses and once without glasses with a 1 month break between. At both read-outs the cases were shown at lower dose or standard dose level to quantify the influence of both variables (eyewear vs. image quality) on nodule sensitivity. RESULTS: The sensitivity of CT for lung nodules increased significantly using Gunnar eyewear for two readers and insignificantly for two other readers. Over all, the mean sensitivity of all radiologist raised significantly from 50% to 53%, using the glasses (P value = 0.034). In contrast, sensitivity for lung nodules was not significantly affected by lowering the image quality from 150 to 40 ref mAs. The average sensitivity was 52% at low dose level, that was even 0.7% higher than at standard dose level (P value = 0.40). The strongest impact on sensitivity had the factors readers and nodule location (lung segments). CONCLUSION: Sensitivity for lung nodules was significantly enhanced by Gunnar eyewear (+3%), while lower image quality (40 ref mAs) had no impact on nodule sensitivity. Not using the glasses had a bigger impact on sensitivity than lowering the image quality.

Usefulness of augmented reality in radiological protection education and training for interventional radiologists.

OBJECTIVE: The aim of this work is to evaluate the usefulness of using augmented reality (AR) to train medical professionals in radiological protection (RP) in fluoroscopy. METHODS: A Microsoft HoloLens 2 device has been used to simulate a fluoroscopic device. The teaching scenario considers a Philips Azurion able to rotate to pre-defined gantry positions,a dorsal decubitus patient and a ceiling shield. Radiation exposures were simulated using the FLUKA Monte Carlo code. 11 radiologists were asked to reproduce their positioning as per a clinical procedure and to correctly position the ceiling shield. Then, they were presented with the radiation exposure of their choices and were able to further optimise it. After the session, they were asked to complete a questionnaire. RESULTS: Users rated the AR educational approach as Intuitive and relevant to RP education (35%) and inspiring to deepen their knowledge (18%). Nevertheless, a negative aspect was mainly the difficulty in dealing with the system (58%). Although the participants were radiologists, a minority recognised themselves as having accurate knowledge of the RP (18%), indicating a relevant knowledge gap. CONCLUSION: The usefulness of using AR in RP education for radiologists has been shown. The visual aid of such technology is likely to improve the consolidation of practical knowledge. ADVANCES IN KNOWLEDGE: The use of interactive teaching techniques has the possibility to both help radiology professionals consolidate their radiation protection training and confidence in their practices.

Incorporation of CAD (computer-aided detection) with thin-slice lung CT in routine 18F-FDG PET/CT imaging read-out protocol for detection of lung nodules.

OBJECTIVE: To evaluate the detection rate and performance of 18F-FDG PET alone (PET), the combination of PET and low-dose thick-slice CT (PET/lCT), PET and diagnostic thin-slice CT (PET/dCT), and additional computer-aided detection (PET/dCT/CAD) for lung nodules (LN)/metastases in tumor patients. Along with this, assessment of inter-reader agreement and time requirement for different techniques were evaluated as well. METHODS: In 100 tumor patients (56 male, 44 female; age range: 22-93 years, mean age: 60 years) 18F-FDG PET images, low-dose CT with shallow breathing (5 mm slice thickness), and diagnostic thin-slice CT (1 mm slice thickness) in full inspiration were retrospectively evaluated by three readers with variable experience (junior, mid-level, and senior) for the presence of lung nodules/metastases and additionally analyzed with CAD. Time taken for each analysis and number of the nodules detected were assessed. Sensitivity, specificity, positive and negative predictive value, accuracy, and Receiver operating characteristic (ROC) analysis of each technique was calculated. Histopathology and/or imaging follow-up served as reference standard for the diagnosis of metastases. RESULTS: Three readers, on an average, detected 40 LN in 17 patients with PET only, 121 LN in 37 patients using ICT, 283 LN in 60 patients with dCT, and 282 LN in 53 patients with CAD. On average, CAD detected 49 extra LN, missed by the three readers without CAD, whereas CAD overall missed 53 LN. There was very good inter-reader agreement regarding the diagnosis of metastases for all four techniques (kappa: 0.84-0.93). The average time required for the evaluation of LN in PET, lCT, dCT, and CAD was 25, 31, 60, and 40 s, respectively; the assistance of CAD lead to average 33% reduction in time requirement for evaluation of lung nodules compared to dCT. The time-saving effect was highest in the less experienced reader. Regarding the diagnosis of metastases, sensitivity and specificity combined of all readers were 47.8%/96.2% for PET, 80.0%/81.9% for PET/lCT, 100%/56.7% for PET/dCT, and 95.6%/64.3% for PET/CAD. No significant difference was observed regarding the ROC AUC (area under the curve) between the imaging methods. CONCLUSION: Implementation of CAD for the detection of lung nodules/metastases in routine 18F-FDG PET/CT read-out is feasible. The combination of diagnostic thin-slice CT and CAD significantly increases the detection rate of lung nodules in tumor patients compared to the standard PET/CT read-out. PET combined with low-dose CT showed the best balance between sensitivity and specificity regarding the diagnosis of metastases per patient. CAD reduces the time required for lung nodule/metastasis detection, especially for less experienced readers.

Evaluation of the anti-peristaltic effect of glucagon and hyoscine on the small bowel: comparison of intravenous and intramuscular drug administration.

PURPOSE: To evaluate prospectively duration and effectiveness of aperistalsis achieved by glucagon(GLU) or hyoscine N-butylbromide(HBB) following various administration routes. MATERIALS AND METHODS: Six volunteers underwent Magnetic Resonance Imaging (MRI) after standardized oral preparation in random order five separate MR examinations with both spasmolytic agents (HBB intravenous(i.v.) or intramuscular(i.m.), GLU i.v. or i.m., and a combined scheme). The MR protocol included a sagittal 2D cross-section of the small bowel with a temporal resolution of 0.55 s acquired over 60 to 90 min. To quantify bowel motility, small bowel cross-sectional areas were summated over time. RESULTS: The anti-peristaltic i.v. effects of HBB and glucagon started on average after 85 s/65 s and ended after 21 min/23.3 min, respectively. By comparison, the anti-peristaltic effects of i.m. HBB and glucagon started significantly later 5.1/11.6 min (P = 0.001; Wilcoxon signed ranks test) and lasted for 17.7/28.2 min with greater inter-individual differences (P = 0.012; Brown-Forsythe test). The combined scheme resulted in a rapid onset after 65 s with effect duration of 31 min. CONCLUSION: Anti-peristaltic effects on the small bowel are drug dependant, i.e., their onset is faster and more reliable when administering i.v. than i.m.. Combining i.v. GLU with i.m. HBB provides an early onset of effect, sustained spasmolysis and the highest degree of motility impairment. KEY POINTS: • Anti-persitaltic agents are widely used before various diagnostic procedures of the abdomen. • The combination of iv-glucagon with im-hyoscine provides reliable spasmolysis with early onset. • Intravenous spasmolysis is more reliable compared to intramuscular administration. • Intravenous glucagon has a prolonged spasmolytic effect compared to intravenous hyoscine.

Multidetector CT and postprocessing in planning and assisting in minimally invasive bronchoscopic airway interventions.

A widening spectrum of increasingly advanced bronchoscopic techniques is available for the diagnosis and treatment of various bronchopulmonary diseases. The evolution of computed tomography (CT)-multidetector CT in particular-has paralleled these advances. The resulting development of two-dimensional and three-dimensional (3D) postprocessing techniques has complemented axial CT interpretation in providing more anatomically familiar information to the pulmonologist. Two-dimensional techniques such as multiplanar recontructions and 3D techniques such as virtual bronchoscopy can provide accurate guidance for increasing yield in transbronchial needle aspiration and transbronchial biopsy of mediastinal and hilar lymph nodes. Sampling of lesions located deeper within the lung periphery via bronchoscopic pathways determined at virtual bronchoscopy are also increasingly feasible. CT fluoroscopy for real-time image-guided sampling is now widely available; electromagnetic navigation guidance is being used in select centers but is currently more costly. Minimally invasive bronchoscopic techniques for restoring airway patency in obstruction caused by both benign and malignant conditions include mechanical strategies such as airway stent insertion and ablative techniques such as electrocauterization and cryotherapy. Multidetector CT postprocessing techniques provide valuable information for planning and surveillance of these treatment methods. In particular, they optimize the evaluation of dynamic obstructive conditions such as tracheobronchomalacia, especially with the greater craniocaudal coverage now provided by wide-area detectors. Multidetector CT also provides planning information for bronchoscopic treatment of bronchopleural fistulas and bronchoscopic lung volume reduction for carefully selected patients with refractory emphysema.

The Columbus steerable guidewire in neurointerventions: early clinical experience and applications.

OBJECTIVE: To report our early experience in using the steerable 'Columbus' guidewire, also known as 'Drivewire' in the USA, and its potential applications in neurovascular interventions. METHODS: Neurointerventions in 36 patients (20 female, 16 male) using the steerable Columbus guidewire were recorded from August 2019 to December 2020 and included a variety of neurovascular procedures: Treatment of aneurysms (n=17), thrombectomy in acute ischemic stroke (n=12), and others (n=7), such as treatment of stenosis and embolization procedures. Immediate follow-up with digital subtraction angiography and tracking of each patient's clinical outcome was performed. RESULTS: In 35 out of 36 cases, the target vessel was reached with Columbus, including advancement of the appropriate microcatheter. In 14 cases, additional wires were used, mainly because of the nature of the procedures (eg, use of multiple wires/buddy wires or exchange maneuvers). In five cases, the Columbus wire was damaged by the operator and had to be replaced. Peri-interventional complications occurred in two patients, neither attributed to the Columbus guidewire. CONCLUSIONS: The new Columbus neurovascular guidewire has the unique ability to be shaped within the patient. Currently available versions lack torquability compared with other available guidewires but offer tremendous support at the tip, allowing maneuvers which are impossible with other wires on the market.