Preoperative pancreatic radiologic characteristics predict pancreatic-specific complications before pancreaticoduodenectomy: the pancreatic acinar radiologic score.

BACKGROUND: High acinar pancreatic contents are associated with a higher rate of postpancreatectomy acute pancreatitis and pancreatic fistula formation (POPF). Predicting acinar contents preoperatively might identify those at high risk of developing postoperative complications. METHODS: A multivariable analysis was performed to identify radiological factors associated with high pancreatic acinar content at histology in patients undergoing pancreaticoduodenectomy. Clinical and radiological variables identified were used to build a composite score predicting low, moderate, and high acinar pancreatic contents. RESULTS: Pancreatic density, wirsung caliber, and pancreatic thickness on preoperative CT-scan predicted acinar contents. These three variables predicted low, moderate, and high acinar content in 94 (26%), 122 (33.6%), and 147 (40.5%) patients, respectively. Patients with high radiological acinar scores compared with patients with intermediate-low risk scores were more frequently male (73.4% vs. 54.1%; p = 0.0003), obese (14% vs. 6%; p = 0.01), and had a statistically significant higher rate of pancreatic-specific complications (23.8% vs. 8.33%; p = 0.01), POPF (12.9% vs. 4.63%; p = 0.005) and pancreaticogastrostomy bleeding (10.8% vs. 4.17%; p = 0.01). CONCLUSION: A simple radiological score combining pancreatic thickness, density, and wirsung caliber at CT scan preoperatively predicts patients with pancreatic parenchyma that are at higher risk of postoperative pancreatic-specific complications.

Radiation dose and image quality in intraoperative CT (iCT) angiography of the brain with stereotactic head frames.

OBJECTIVES: Intraoperative CT (iCT) angiography of the brain with stereotactic frames is an integral part of navigated neurosurgery. Validated data regarding radiation dose and image quality in these special examinations are not available. We therefore investigated two iCT protocols in this IRB-approved study. METHODS: Retrospective analysis of patients, who received a cerebral stereotactic iCT angiography on a 128 slice CT scanner between February 2016 and December 2017. In group A, automated tube current modulation (ATCM; reference value 410 mAs) and automated tube voltage selection (reference value 120 kV) were enabled, and only examinations with a selected voltage of 120 kV were included. In group B, fixed parameters were applied (300 mAs, 120 kV). Radiation dose was measured by assessing the volumetric CT dose index (CTDIvol), dose length product (DLP) and effective dose (ED). Signal-to-noise ratio (SNR) and image noise were assessed for objective image quality, visibility of arteries and grey-white differentiation for subjective image quality. RESULTS: Two hundred patients (n = 100 in each group) were included. In group A, median selected tube current was 643 mAs (group B, 300 mAs; p < 0.001). Median values of CTDIvol, DLP and ED were 91.54 mGy, 1561 mGy cm and 2.97 mSv in group A, and 43.15 mGy, 769 mGy cm and 1.46 mSv in group B (p < 0.001). Image quality did not significantly differ between groups (p > 0.05). CONCLUSIONS: ATCM yielded disproportionally high radiation dose due to substantial tube current increase at the frame level, while image quality did not improve. Thus, ATCM should preferentially be disabled. KEY POINTS: • Automated tube current modulation (ATCM) yields disproportionally high radiation dose in intraoperative CT angiography of the brain with stereotactic head frames. • ATCM does not improve overall image quality in these special examinations. • ATCM is not yet optimised for CT angiography of the brain with major extracorporeal foreign materials within the scan range.

Submillisievert Computed Tomography of the Chest Using Model-Based Iterative Algorithm: Optimization of Tube Voltage With Regard to Patient Size.

OBJECTIVE: The aim of this study was to define optimal tube potential for soft tissue and vessel visualization in dose-reduced chest CT protocols using model-based iterative algorithm in average and overweight patients. METHODS: Thirty-six patients receiving chest CT according to 3 protocols (120 kVp/noise index [NI], 60; 100 kVp/NI, 65; 80 kVp/NI, 70) were included in this prospective study, approved by the ethics committee. Patients' physical parameters and dose descriptors were recorded. Images were reconstructed with model-based algorithm. Two radiologists evaluated image quality and lesion conspicuity; the protocols were intraindividually compared with preceding control CT reconstructed with statistical algorithm (120 kVp/NI, 20). Mean and standard deviation of attenuation of the muscle and fat tissues and signal-to-noise ratio of the aorta were measured. RESULTS: Diagnostic images (lesion conspicuity, 95%-100%) were acquired in average and overweight patients at 1.34, 1.02, and 1.08 mGy and at 3.41, 3.20, and 2.88 mGy at 120, 100, and 80 kVp, respectively. Data are given as CT dose index volume values. CONCLUSIONS: Model-based algorithm allows for submillisievert chest CT in average patients; the use of 100 kVp is recommended.

Quantitative evaluation of beam-hardening artefact correction in dual-energy CT myocardial perfusion imaging.

OBJECTIVES: To assess quantitatively the impact of a novel reconstruction algorithm ("kernel") with beam-hardening correction (BHC) on beam-hardening artefacts of the myocardium at dual-energy CT myocardial perfusion imaging (DE-CTMPI). METHODS: Rest-series of DE-CTMPI examinations from 14 patients were retrospectively analyzed. Six image series were reconstructed for each patient: a) 100 kV, b) 140 kV, and c) linearly blended MIX0.5, each with BHC (D33f kernel) and without (D30f kernel). Seven hundred and fifty-six myocardial regions were assessed. Seven equal regions of interest divided the myocardium in the axial section. Three subdivisions were created within these regions in areas prone to BHA. Reports of SPECT studies performed within 30 days of CT examination were used to confirm the presence and location of true perfusion defects. Paired student t-test was used for statistical evaluation. RESULTS: Overall mean myocardial attenuation was lower using BHC (D30f: 87.3 ± 24.1 HU; D33f: 85.5 ± 21.5 HU; p = 0.009). Overall relative difference from average myocardial attenuation (RDMA) was more homogeneous using BHC (D30f: -0.3 ± 11.4 %; D33f: 0.1 ± 10.1 %; p < 0.001). Changes in RDMA were greatest in the posterobasal myocardium (D30f: -16.2 ± 10.0 %; D33f: 3.4 ± 10.7 %; p < 0.001). CONCLUSIONS: A dedicated reconstruction algorithm with BHC can significantly reduce beam-hardening artefacts in DE-CTMPI. KEY POINTS: • Beam-hardening artefacts (BHA) cause interference with attenuation-based CT myocardial perfusion assessment (CTMPI). • BHA occur mostly in the posterobasal left ventricular wall. • Beam-hardening correction homogenized and decreased mean myocardial attenuation. • BHC can help avoid false-positive findings and increase specificity of static CTMPI.

State of the Art: Iterative CT Reconstruction Techniques.

Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limitations in CT imaging.

CT Evaluation of Small-Diameter Coronary Artery Stents: Effect of an Integrated Circuit Detector with Iterative Reconstruction.

PURPOSE: To use suitable objective methods of analysis to assess the influence of the combination of an integrated-circuit computed tomographic (CT) detector and iterative reconstruction (IR) algorithms on the visualization of small (≤3-mm) coronary artery stents. MATERIALS AND METHODS: By using a moving heart phantom, 18 data sets obtained from three coronary artery stents with small diameters were investigated. A second-generation dual-source CT system equipped with an integrated-circuit detector was used. Images were reconstructed with filtered back-projection (FBP) and IR at a section thickness of 0.75 mm (FBP75 and IR75, respectively) and IR at a section thickness of 0.50 mm (IR50). Multirow intensity profiles in Hounsfield units were modeled by using a sum-of-Gaussians fit to analyze in-plane image characteristics. Out-of-plane image characteristics were analyzed with z upslope of multicolumn intensity profiles in Hounsfield units. Statistical analysis was conducted with one-way analysis of variance and the Student t test. RESULTS: Independent of stent diameter and heart rate, IR75 resulted in significantly increased xy sharpness, signal-to-noise ratio, and contrast-to-noise ratio, as well as decreased blurring and noise compared with FBP75 (eg, 2.25-mm stent, 0 beats per minute; xy sharpness, 278.2 vs 252.3; signal-to-noise ratio, 46.6 vs 33.5; contrast-to-noise ratio, 26.0 vs 16.8; blurring, 1.4 vs 1.5; noise, 15.4 vs 21.2; all P < .001). In the z direction, the upslopes were substantially higher in the IR50 reconstructions (2.25-mm stent: IR50, 94.0; IR75, 53.1; and FBP75, 48.1; P < .001). CONCLUSION: The implementation of an integrated-circuit CT detector provides substantially sharper out-of-plane resolution of coronary artery stents at 0.5-mm section thickness, while the use of iterative image reconstruction mostly improves in-plane stent visualization.

Endoleak and in-stent thrombus detection with CT angiography in a thoracic aortic aneurysm phantom at different tube energies using filtered back projection and iterative algorithms.

PURPOSE: To determine the lower limit of dose reduction with hybrid and fully iterative reconstruction algorithms in detection of endoleaks and in-stent thrombus of thoracic aorta with computed tomographic (CT) angiography by applying protocols with different tube energies and automated tube current modulation. MATERIALS AND METHODS: The calcification insert of an anthropomorphic cardiac phantom was replaced with an aortic aneurysm model containing a stent, simulated endoleaks, and an intraluminal thrombus. CT was performed at tube energies of 120, 100, and 80 kVp with incrementally increasing noise indexes (NIs) of 16, 25, 34, 43, 52, 61, and 70 and a 2.5-mm section thickness. NI directly controls radiation exposure; a higher NI allows for greater image noise and decreases radiation. Images were reconstructed with filtered back projection (FBP) and hybrid and fully iterative algorithms. Five radiologists independently analyzed lesion conspicuity to assess sensitivity and specificity. Mean attenuation (in Hounsfield units) and standard deviation were measured in the aorta to calculate signal-to-noise ratio (SNR). Attenuation and SNR of different protocols and algorithms were analyzed with analysis of variance or Welch test depending on data distribution. RESULTS: Both sensitivity and specificity were 100% for simulated lesions on images with 2.5-mm section thickness and an NI of 25 (3.45 mGy), 34 (1.83 mGy), or 43 (1.16 mGy) at 120 kVp; an NI of 34 (1.98 mGy), 43 (1.23 mGy), or 61 (0.61 mGy) at 100 kVp; and an NI of 43 (1.46 mGy) or 70 (0.54 mGy) at 80 kVp. SNR values showed similar results. With the fully iterative algorithm, mean attenuation of the aorta decreased significantly in reduced-dose protocols in comparison with control protocols at 100 kVp (311 HU at 16 NI vs 290 HU at 70 NI, P ≤ .0011) and 80 kVp (400 HU at 16 NI vs 369 HU at 70 NI, P ≤ .0007). CONCLUSION: Endoleaks and in-stent thrombus of thoracic aorta were detectable to 1.46 mGy (80 kVp) with FBP, 1.23 mGy (100 kVp) with the hybrid algorithm, and 0.54 mGy (80 kVp) with the fully iterative algorithm.

Emergency CT head and neck imaging: effects of swimmer's position on dose and image quality.

OBJECTIVES: To compare the effects of different arm positions on dose exposure and image quality (IQ) in cervical spine CT after trauma in different patient groups. METHODS: Patients in standard (STD = 126) and in swimmer's position (SWIM = 254) were included. Body mass index (BMI subgroup 1 = underweight to subgroup 4 = obese), anterior-posterior diameter (AP), left-right diameter (LR), area of an ellipse (AoE) and angle between the humeral heads (optimal STD < 3°, optimal SWIM > 10°) were used as grouping criteria. Computed tomography dose index (CTDI) was documented. Two radiologists rated the IQ at three levels (CV1/2, CV4/5, CV7/T1) using a semi-quantitative scale (0 = not diagnostic, 1 = diagnostic with limitations, 2 = diagnostic without limitations). The Mann-Whitney U test correlations of grouping criteria with dose effects and intra-class correlation (ICC) were calculated. RESULTS: ICC was 0.87. BMI grouping showed the strongest correlation with dose effects: CTDI of optimal STD versus optimal SWIM positioning was 3.17 mGy versus 2.46 mGy (subgroup 1), 5.47 mGy versus 3.97 mGy (subgroup 2), 7.35 mGy versus 5.96 mGy (subgroup 3) and 8.71 mGy versus 8.18 mGy (subgroup 4). Mean IQ at CV7/T1 was 1.65 versus 1.23 (subgroup 1), 1.27 versus 1.46 (subgroup 2), 1.06 versus 1.46 (subgroup 3), 0.79 versus 1.5 (subgroup 4). CONCLUSION: Patients with a BMI > 20 kg/m(2) benefited from both potential dose reduction and improved image quality at the critical cervicothoracic junction when swimmer's position was used. KEY POINTS: • BMI is a useful metric for personalized optimization in CT for the c-spine. • Using swimmer's position, patients can benefit from dose reduction. • In some patients a superior image quality can be achieved with swimmer's position. • For swimmer's positioning an angle of more than 10° is optimal.

Reduced radiation dose and improved image quality at cardiovascular CT angiography by automated attenuation-based tube voltage selection: intra-individual comparison.

OBJECTIVES: To evaluate the effect of automated tube voltage selection on radiation dose and image quality at cardiovascular CT angiography (CTA). METHODS: We retrospectively analysed paired studies in 72 patients (41 male, 60.5 ± 16.5 years), who had undergone CTA acquisitions of the heart or aorta both before and after the implementation of an automated x-ray tube voltage selection algorithm (ATVS). All other parameters were kept identical between the two acquisitions. Subjective image quality (IQ) was rated and objective IQ was measured by image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and figure of merit (FOM). Image quality parameters and effective dose were compared between acquisitions. RESULTS: Overall subjective image quality improved with the percentage of cases scored as adequate or higher increasing from 79 % to 92 % after implementation of ATVS (P = 0.03). SNR (14.1 ± 5.9, 15.7 ± 6.1, P = 0.009), CNR (11.6 ± 5.3, 13.2 ± 5.6, P = 0.011), and FOM (19.9 ± 23.3, 43.8 ± 51.1, P < 0.001) were significantly higher after implementation of ATVS. Mean image noise (24.1 ± 8.4 HU, 22.7 ± 7.1 HU, P = 0.048) and mean effective dose (10.6 ± 5.9 mSv, 8.8 ± 5.0 mSv, P = 0.003) were significantly lower after implementation of ATVS. CONCLUSIONS: Automated tube voltage selection can operator-independently optimize cardiovascular CTA image acquisition parameters with improved image quality at reduced dose. KEY POINTS: • Automatic tube voltage selection optimizes tube voltage for each individual patient. • In this population, overall radiation dose decreased while image quality improved. • This tool may become valuable for improving dose/quality ratio.

Automated quantification of epicardial adipose tissue using CT angiography: evaluation of a prototype software.

OBJECTIVES: This study evaluated the performance of a novel automated software tool for epicardial fat volume (EFV) quantification compared to a standard manual technique at coronary CT angiography (cCTA). METHODS: cCTA data sets of 70 patients (58.6 ± 12.9 years, 33 men) were retrospectively analysed using two different post-processing software applications. Observer 1 performed a manual single-plane pericardial border definition and EFVM segmentation (manual approach). Two observers used a software program with fully automated 3D pericardial border definition and EFVA calculation (automated approach). EFV and time required for measuring EFV (including software processing time and manual optimization time) for each method were recorded. Intraobserver and interobserver reliability was assessed on the prototype software measurements. T test, Spearman's rho, and Bland-Altman plots were used for statistical analysis. RESULTS: The final EFVA (with manual border optimization) was strongly correlated with the manual axial segmentation measurement (60.9 ± 33.2 mL vs. 65.8 ± 37.0 mL, rho = 0.970, P < 0.001). A mean of 3.9 ± 1.9 manual border edits were performed to optimize the automated process. The software prototype required significantly less time to perform the measurements (135.6 ± 24.6 s vs. 314.3 ± 76.3 s, P < 0.001) and showed high reliability (ICC > 0.9). CONCLUSIONS: Automated EFVA quantification is an accurate and time-saving method for quantification of EFV compared to established manual axial segmentation methods. KEY POINTS: • Manual epicardial fat volume quantification correlates with risk factors but is time-consuming. • The novel software prototype automates measurement of epicardial fat volume with good accuracy. • This novel approach is less time-consuming and could be incorporated into clinical workflow.

Dynamic CT myocardial perfusion imaging: performance of 3D semi-automated evaluation software.

OBJECTIVES: To evaluate the performance of three-dimensional semi-automated evaluation software for the assessment of myocardial blood flow (MBF) and blood volume (MBV) at dynamic myocardial perfusion computed tomography (CT). METHODS: Volume-based software relying on marginal space learning and probabilistic boosting tree-based contour fitting was applied to CT myocardial perfusion imaging data of 37 subjects. In addition, all image data were analysed manually and both approaches were compared with SPECT findings. Study endpoints included time of analysis and conventional measures of diagnostic accuracy. RESULTS: Of 592 analysable segments, 42 showed perfusion defects on SPECT. Average analysis times for the manual and software-based approaches were 49.1 ± 11.2 and 16.5 ± 3.7 min respectively (P < 0.01). There was strong agreement between the two measures of interest (MBF, ICC = 0.91, and MBV, ICC = 0.88, both P < 0.01) and no significant difference in MBF/MBV with respect to diagnostic accuracy between the two approaches for both MBF and MBV for manual versus software-based approach; respectively; all comparisons P > 0.05. CONCLUSIONS: Three-dimensional semi-automated evaluation of dynamic myocardial perfusion CT data provides similar measures and diagnostic accuracy to manual evaluation, albeit with substantially reduced analysis times. This capability may aid the integration of this test into clinical workflows. KEY POINTS: • Myocardial perfusion CT is attractive for comprehensive coronary heart disease assessment. • Traditional image analysis methods are cumbersome and time-consuming. • Automated 3D perfusion software shortens analysis times. • Automated 3D perfusion software increases standardisation of myocardial perfusion CT. • Automated, standardised analysis fosters myocardial perfusion CT integration into clinical practice.

Integrated cardiothoracic imaging with computed tomography.

The respiratory and the cardiovascular systems are intimately connected. Because of the high degree of morphological and functional interaction, pathophysiological processes in one compartment are likely to induce adaptive changes in the other. Computed tomography (CT) plays a central role in the diagnostic work up of both thoracic and cardiac disorders. Historically, these two systems have been evaluated separately; however, CT technology has evolved remarkably over recent decades. Up-to-date advanced imaging strategies allow for a combined assessment of the cardiopulmonary unit. Besides improved techniques of electrocardiogram (ECG)-synchronization for obtaining both morphological and functional information, latest advances of dual-source CT (DSCT) have shown great promise for even more comprehensive integrated cardiothoracic imaging.

The role of follow-up ultrasound and clinical parameters after abdominal MDCT in patients with multiple trauma.

BACKGROUND: Beside its value during the initial trauma work-up (focused assessment with sonography for trauma), ultrasound (US) is recommended for early follow-up examinations of the abdomen in multiple injured patients. However, multidetector CT (MDCT) has proven to reliably diagnose traumatic lesions of abdominal organs, to depict their extent, and to assess their clinical relevance. PURPOSE: To evaluate the diagnostic impact of follow-up US studies after MDCT of the abdomen and to identify possible clinical parameters indicating the need of a follow-up US. MATERIAL AND METHODS: During a 30-month period, patients with suspected multiple trauma were allocated. Patients with admission to the ICU, an initial abdominal MDCT scan, and an US follow-up examination after 6 and 24 h were included. Two patient cohorts were defined: patients with normal abdominal MDCT (group 1), patients with trauma-related pathologic abdominal MDCT (group 2). In all patients, parameters indicating alteration of vital functions or hemorrhage within the first 24 h were obtained by reviewing the medical charts. RESULTS: Forty-four of 193 patients were included: 24 were categorized in group 1 (mean age, 41.1 years; range, 21-90 years), 20 in group 2 (mean age, 36.6 years; range, 16-71 years). In group 1, US did not provide new information compared to emergency MDCT. In group 2, there were no contradictory 6- and 24-h follow-up US findings. In patients with positive MDCT findings and alterations of clinical parameters, US did not detect progression of a previously diagnosed pathology or any late manifestation of such a lesion. In none of the patients with negative abdominal MDCT and pathological clinical parameters US indicated an abdominal injury. CONCLUSION: Routine US follow-up does not yield additional information after abdominal trauma. In patients with MDCT-proven organ lesions, follow-up MDCT should be considered if indicated by abnormal clinical and/or laboratory findings.

Low-dose CT in body-packers: delineation of body packs and radiation dose in a porcine model.

PURPOSE: To compare low-dose computed tomography (CT) with standard CT and conventional radiography (CR) regarding delineation of body packs and radiation dose. METHODS: Nine samples of illicit drugs including cocaine, heroin, and hashish were positioned in the rectum of a 121.5 kg pig cadaver. Each sample was scanned on a 64-row MDCT with 120 kV: one standard modulated pelvic protocol (STD), and without modulation at 80 mA (LD80), 30 mA (LD30), and 10 mA (LD10). Additionally, conventional abdominal anterior-posterior radiographs (77 kV and 106 ± 13 mA) were taken. Body pack characteristics (wrapping, content, shape) were rated independently by two radiologists and summarized to a delineation score from 0 to 9 with scores ≥6 representing sufficient delineation. Mean delineation scores were calculated for CR and CT protocols. These were additionally differentiated for readings in soft tissue (S), lung (L), user defined, variable window settings (V), and in cumulative window evaluation including all the other window settings (SLV). Effective doses were calculated (mSv). RESULTS: The CR delineation score was insufficient (3.1 ± 2.5; 2.4 ± 0.3 mSv). For CT, the SLV window setting performed best (p < 0.01). Its score significantly (p < 0.01) declined with decreasing effective radiation doses: STD (8.8 ± 0.5; 10.6 mSv), LD80 (8.2 ± 0.7; 2.6 mSv), LD30 (6.8 ± 1.3; 1.0 mSv), and LD10 (4.6 ± 1.9; 0.3 mSv). Thus, LD30 was the protocol using the lowest but sufficient dose. Moreover, for LD30 further differentiation between the particular window settings resulted in scores of 6.4 ± 1.3 (L), 6.3 ± 1.2 (V), and 3.1 ± 1.0 (S). CONCLUSIONS: With appropriate window settings, low-dose CT at 30 mA allowed for sufficient body-pack delineation below the dose of CR, which itself performed insufficient.

Position of polyaxial versus monoaxial screws in locked plating for proximal humeral fractures: analysis of a prospective randomized study.

BACKGROUND: Aim of the study was to compare the chosen position of polyaxial locking screws with the position of monoaxial screws in the humeral head of proximal humeral fractures treated by locked plating. METHODS: In a prospective randomized observational study, 124 consecutive patients (mean age 70.9±14.8 years) sustaining a displaced proximal humeral fracture were treated with either monoaxial or polyaxial screw-inserted locking plate fixation. The chosen positions of locking screws were identified from standardized postoperative radiographs in anteroposterior and outlet-view, with regard to a regional mapping of the humeral head. RESULTS: In monoaxial locking technique, a mean of 6 screws purchased the humeral head (95% CI 5.1-6.2), and in polyaxial locking technique, a mean of 4 screws (95% CI 3.3-4.5), respectively. Screws were placed in the regions superolateral: monoaxial 24.8%, polyaxial 20.7% (p=0.49); superomedial: monoaxial 21.9%, polyaxial 20.0% (p=0.433); inferolateral: monoaxial 32.5%, polyaxial 35.0% (p=0.354); inferomedial: monoaxial 20.8%, polyaxial 24.2% (p=0.07), superoposterior: monoaxial 45.5%, polyaxial 30.8% (p=0.57); superoanterior: monoaxial 4.4%, polyaxial 8.3% (p=0.33); inferoposterior: monoaxial 22.5%, polyaxial 29.8% (p=0.49) and inferoanterior: monoaxial 27.5%, polyaxial: 31.2% (p=0.09). CONCLUSION: The chosen screws' position in monoaxial and polyaxial locking plate fixation of displaced proximal humeral fractures do not differ significantly. However, loss of fixation is observed more frequently if the fixation did not include at least one screw within the superoposterior region of the humeral head, suggesting that a screw purchasing the superoposterior region is beneficial in locked plating of proximal humeral fractures. LEVEL OF EVIDENCE: Treatment Study, Level II.

Filtered back projection, adaptive statistical iterative reconstruction, and a model-based iterative reconstruction in abdominal CT: an experimental clinical study.

PURPOSE: To compare objective and subjective image quality parameters of three image reconstruction algorithms of different generations at routine multidetector computed tomographic (CT) examinations of the abdomen. MATERIALS AND METHODS: This institutional review board-approved study included 22 consecutive patients (mean age, 56.1 years ± 15.8 [standard deviation]; mean weight, 79.1 kg ± 14.8) who underwent routine CT examinations of the abdomen. A low-contrast phantom was used for objective quality control. Raw data sets were reconstructed by using filtered back projection (FPB), adaptive statistical iterative reconstruction (ASIR), and a model-based iterative reconstruction (MBIR). Radiologists used a semiquantitative scale (-3 to +3) to rate subjective image quality and artifacts, comparing both FBP and MBIR images with ASIR images. The Wilcoxon test and the intraclass correlation coefficient were used to evaluate the data. Measurements of objective noise and CT numbers of soft tissue structures were compared with analysis of variance. RESULTS: The phantom study revealed an improved detectability of low-contrast targets for MBIR compared with ASIR or FBP. Subjective ratings showed higher image quality for MBIR, with better resolution (median value, 2; range, 1 to 3), lower noise (2; range, 1 to 3), and finer contours (2; range, 1 to 2) compared with ASIR (all P < .001). FBP performed inferiorly (0, range, -2 to 0]; -1 [range, -3 to 0]; 0 [range, -1 to 0], respectively; all, P < .001). Mean interobserver correlation was 0.9 for image perception and 0.7 for artifacts. Objective noise for FBP was 14%-68% higher and for MBIR was 18%-47% lower than that for ASIR (P < .001). CONCLUSION: The MBIR algorithm considerably improved objective and subjective image quality parameters of routine abdominal multidetector CT images compared with those of ASIR and FBP.

Polytrauma: optimal imaging and evaluation algorithm.

Traumatic injuries are the leading cause of death in adults < 45 years of age. Musculoskeletal trauma accounts for a substantial number of injuries in patients sustaining polytrauma. The diagnostic work-up of those patients is challenging, complex, and requires a structured and interdisciplinary workflow. Multidetector CT (MDCT) is considered the imaging modality of choice due to remarkable technical developments in recent years. Besides the evaluation of cranial, chest, and abdominal injuries, MDCT allows for integrated imaging of musculoskeletal trauma within a single CT examination. In this context, CT angiography facilitates the detection of coexisting vascular injuries after trauma of the skeleton. In addition, recent technologies (e.g., dual-energy CT) provide promising applications such as metal artifact reduction. This article summarizes the basic principles of interdisciplinary management of polytrauma patients, reviews recent advances of CT technology that have enabled comprehensive trauma imaging, provides appropriate scan protocols, and discusses the radiologic evaluation of musculoskeletal findings.

Incidence of delayed and missed diagnoses in whole-body multidetector CT in patients with multiple injuries after trauma.

BACKGROUND: Whole-body CT (WBCT) is the imaging modality of choice during the initial diagnostic work-up of multiple injured patients in order to identify serious injuries and initiate adequate treatment immediately. However, delayed diagnosed or even missed injuries have been reported frequently ranging from 1.3% to 47%. PURPOSE: To highlight commonly missed lesions in WBCT of patients with multiple injuries. MATERIAL AND METHODS: A total of 375 patients (age 42.8 ± 17.9 years, ISS 26.6 ± 17.0) with a WBCT (head to symphysis) were included. The final CT report was compared with clinical and operation reports. Discrepant findings were recorded and grouped as relevant and non-relevant to further treatment. In both groups, an experienced trauma radiologist read the CT images retrospectively, whether these lesions were missed or truly not detectable. RESULTS: In 336 patients (89.6%), all injuries in the regions examined were diagnosed correctly in the final reports of the initial CT. Forty-eight patients (12.8%) had injuries in regions of the body that were not included in the CT. Fourteen patients (3.7%) had injuries that did not require further treatment. Twenty-five patients (6.7%) had injuries that required further treatment. With secondary interpretation, 85.4% of all missed lesions could be diagnosed in retrospect from the primary CT data-set. Small pancreatic and bowel contusions were identified as truly non-detectable. CONCLUSION: In multiple traumas, only a few missed injuries in initial WBCT reading are clinically relevant. However, as the vast majority of these injuries are detectable, the radiologist has to be alert for commonly missed findings to avoid a delayed diagnosis.

Management of a rare mandibular giant cell tumor of bone by neoadjuvant denosumab therapy and surgery: A 4-year follow-up case report.

INTRODUCTION: Giant cell tumor of bone (GCTB) is a very rare tumor encountered in the jaws and its histology is quite similar to the more common giant cell granuloma of the jaws (GCGJ). These two entities can be easily confused in maxillofacial region. They are classically managed surgically, but in some localizations and in specific medical-surgical contexts, neoadjuvant therapy with denosumab may be indicated. This report tends to reinforce existing evidence in favor of the use of a neoadjuvant approach, particularly for localization of GCTB in the orofacial region. PRESENTATION OF CASE: This is a 57-year-old female patient, an alcoholic smoker, in whom a voluminous mandibular radiolucent lesion was discovered during a routine X-ray by her dentist. After medical imaging assessment and incisional biopsy, diagnosis of GCTB was established. A neoadjuvant denosumab therapy was proposed first followed by a secondary surgical curettage. After 4 years' follow-up, complete healing was observed with no recurrence of the lesion. DISCUSSION: Surgical management of aggressive GCTB is risky particularly in localizations involving the sacrum, spine or craniofacial skeleton with a high residual recurrence rate. The use of denosumab to stop tumor progression and facilitate secondary excision surgery is a recent approach that is now well documented in the literature showing promising results with a low rate of side effects. CONCLUSION: This case of mandibular GCTB is to our knowledge the unique case described in this localization and treated by denosumab neoadjuvant therapy followed by surgery with a 4-year follow-up showing a complete healing.

p16 Immunohistochemical Expression as a Surrogate Assessment of CDKN2A Alteration in Gliomas Leading to Prognostic Significances.

CDKN2A is a tumor suppressor gene encoding the p16 protein, a key regulator of the cell cycle. CDKN2A homozygous deletion is a central prognostic factor for numerous tumors and can be detected by several techniques. This study aims to evaluate the extent to which immunohistochemical levels of p16 expression may provide information about CDKN2A deletion. A retrospective study was conducted in 173 gliomas of all types, using p16 IHC and CDKN2A fluorescent in situ hybridization. Survival analyses were performed to assess the prognostic impact of p16 expression and CDKN2A deletion on patient outcomes. Three patterns of p16 expression were observed: absence of expression, focal expression, and overexpression. Absence of p16 expression was correlated with worse outcomes. p16 overexpression was associated with better prognoses in MAPK-induced tumors, but with worse survival in IDH-wt glioblastomas. CDKN2A homozygous deletion predicted worse outcomes in the overall patient population, particularly in IDH-mutant 1p/19q oligodendrogliomas (grade 3). Finally, we observed a significant correlation between p16 immunohistochemical loss of expression and CDKN2A homozygosity. IHC has strong sensitivity and high negative predictive value, suggesting that p16 IHC might be a pertinent test to detect cases most likely harboring CDKN2A homozygous deletion.