Postoperative Extremity Tomosynthesis-A Superimposition-Free Alternative to Standard Radiography?

RATIONALE AND OBJECTIVES: This study investigates the performance of tomosynthesis in the presence of osteosynthetic implants, aiming to overcome superimposition-induced limitations in conventional radiograms. MATERIALS AND METHODS: After surgical fracture induction and subsequent osteosynthesis, 8 cadaveric fracture models (wrist, metacarpus, ankle, metatarsus) were scanned with the prototypical tomosynthesis mode of a multiuse x-ray system. Tomosynthesis protocols at 60, 80, and 116 kV (sweep angle 10°, 13 FPS) were compared with standard radiograms. Five radiologists independently rated diagnostic assessability based on an equidistant 7-point scale focusing on fracture delineation, intra-articular screw placement, and implant positioning. The intraclass correlation coefficient (ICC) was calculated to analyze interrater agreement. RESULTS: Radiation dose in radiography was 0.48 ± 0.26 dGy·cm2 versus 0.12 ± 0.01, 0.36 ± 0.02, and 1.95 ± 0.11 dGy·cm2 for tomosynthesis scans at 60, 80, and 116 kV. Delineation of fracture lines was superior for 80/116 kV tomosynthesis compared with radiograms (P ≤ 0.003). Assessability of intra-articular screw placement was deemed favorable for all tomosynthesis protocols (P ≤ 0.004), whereas superiority for evaluation of implant positioning could not be ascertained (all P's ≥ 0.599). Diagnostic confidence was higher for 80/116 kV tomosynthesis versus radiograms and 60 kV tomosynthesis (P ≤ 0.002). Interrater agreement was good for fracture delineation (ICC, 0.803; 95% confidence interval [CI], 0.598-0.904), intra-articular screw placement (ICC, 0.802; 95% CI, 0.599-0.903), implant positioning (ICC, 0.855; 95% CI, 0.729-0.926), and diagnostic confidence (ICC, 0.842; 95% CI, 0.556-0.934). CONCLUSIONS: In the postoperative workup of extremity fractures, tomosynthesis allows for superior assessment of fracture lines and intra-articular screw positioning with greater diagnostic confidence at radiation doses comparable to conventional radiograms.

The exercise-app Axia for axial spondyloarthritis enhances the home-based exercise frequency in axial spondyloarthritis patients - A cross-sectional survey.

BACKGROUND: Patients with axial spondyloarthritis (axSpA) benefit from regular home-based exercise (HbE). In spite of recommendations, a relevant proportion of German axSpA patients does not adhere to recommended HbE practices. To enhance HbE care, we developed the novel digital therapeutic (DTx) "Axia" compliant with the European medical device regulation (MDR). Axia offers a modern app-based HbE solution with patient educative content and further integrated features. OBJECTIVE: We aimed to assess Axia's efficacy, attractiveness, and functionality through a survey among axSpA-patients involved in the first user tests. METHODS: A mixed-method online questionnaire with 38 items was administered to 37 axSpA volunteers after using Axia. Numeric rating scales (NRS) and likelihood scales were primarily used. RESULTS: HbE frequency significantly increased from a median of 1 day/week to 6 days/week (p < 0.001) by using Axia. Existing HbE practitioners also increased their frequency (median of 4 days/week before, 6 days/week with Axia, p < 0.05). Axia received a median rating of 5 out of 5 stars. On NRS scales, Axia scored a median of 9 for intuitiveness and design, and a median of 8 for entertainment. 64.9% reported improved range of motion, 43.2% reported reduced pain, and 93.6% enhanced disease-specific knowledge. All users recommended Axia to other patients. CONCLUSION: Axia increases axSpA patients HbE frequency, possibly due to its good intuitiveness and design, leading to reduction in pain and subjective improvement of range of motion. This warrants further investigation in large randomized controlled interventional trials to establish its efficacy conclusively and patients adherence to HbE.

Tomosynthesis of the Appendicular Skeleton on a Twin Robotic X-ray System: A Cadaveric Fracture Study.

RATIONALE AND OBJECTIVES: Aiming to offset image quality limitations in radiographs due to superimposition, this study investigates the diagnostic potential of appendicular skeleton tomosynthesis. MATERIALS AND METHODS: Eight cadaveric extremities (four hands and feet) were examined employing the prototypical tomosynthesis mode of a twin robotic X-ray scanner. 12 protocols with varying sweep angles (10, 20 vs. 40°), frame rates (13 vs. 26 fps), and tube voltages (60 vs. 80 kV) were compared to radiographs. Four radiologists separately evaluated cortical and trabecular bone visualization and fracture patterns. Interreader reliability was assessed based on the intraclass correlation coefficient (ICC). RESULTS: Radiation dose in radiography was 0.59 ± 0.20 dGy * cm2 versus 0.11 ± 0.00 to 2.46 ± 0.17 dGy * cm2 for tomosynthesis. Cortical bone display was inferior for radiographs compared to 40° and 20° tomosynthesis. Best results were ascertained for the 80 kV/40°/26 fps protocol. Trabecular bone depiction was also superior in tomosynthesis (p ≤ 0.009) and best with the 80 kV/10°/26 fps setting. Interreader reliability was moderate for cortical bone display (ICC 0.521, 95% confidence interval 0.356-0.641) and good for trabecular bone (0.759, 0.697-0.810). Diagnostic accuracy for articular involvement and multifragment situations was higher in tomosynthesis (93.8-100%/92.2-100%) vs. radiography (85.9%/82.8%.). Diagnostic confidence was also better in tomosynthesis (p ≤ 0.003). CONCLUSION: Compared to radiography, tomosynthesis allows for superior assessability of cortical and trabecular bone and fracture morphology, especially at high framerates. Operating on a multipurpose X-ray system, tomosynthesis of the appendicular skeleton can be performed without additional scanner hardware.

Upright Tomosynthesis of the Lumbar Spine.

RATIONALE AND OBJECTIVES: This experimental study investigates the potential of lumbar spine tomosynthesis to offset the traditional limitations of radiographic and computed tomography imaging, that is, superimposition of anatomy and disregard of physiological load-bearing. MATERIALS AND METHODS: A gantry-free twin robotic scanner was used to obtain lateral radiographs and tomosyntheses of the lumbar spine under weight-bearing conditions in eight body donors. Tomosynthesis protocols varied in terms of sweep angle (20 versus 40°), scan time (2.4 versus 4.8 seconds), and framerate (16 versus 30 fps). Image quality and vertebral endplate assessability were evaluated by five radiologists with 4-8 years of skeletal imaging experience. Aiming to identify potential diagnostic deterioration near the scan volume margins, readers additionally determined the craniocaudal extent of clinically acceptable image quality. RESULTS: Tomosynthesis scans effectuated a substantial dose reduction compared to standard radiographs (3.8 ± 0.2 to 15.4 ± 0.8 dGy*cm2 versus 77.7 ± 34.8 dGy*cm2; p ≤ 0.021). Diagnostic image quality and endplate assessability were deemed highest for the 30 fps wide-angle tomosynthesis protocol with good to excellent interrater reliability (intraclass correlation coefficients: 0.846 and 0.946). Accordingly, the craniocaudal extent of acceptable image quality was substantially larger compared to radiography (26.9 versus 18.9 cm; p < 0.001), whereas no significant difference was ascertained for the tomosynthesis protocols with 16 fps (15.3-22.1 cm; all p ≥ 0.058). CONCLUSION: Combining minimal radiation dose with superimposition-free visualization, 30 fps wide-angle tomosynthesis superseded radiography in all evaluated aspects. With superior diagnostic assessability despite significant dose reduction, load-bearing tomosynthesis appears promising as an alternative for first-line lumbar spine imaging in the future.

Rotational alignment of the lower extremity in the presence of total knee endoprosthesis: Reproducibility of torsion analyses using ultra-low-dose photon-counting CT.

PURPOSE: Leg torsion analysis can provide valuable information in symptomatic patients after total knee arthroplasty. However, extensive beam-hardening and photon-starvation artifacts limit diagnostic assessability and dose reduction potential. For this study, we investigated the reproducibility of rotational measurements in ultra-low-dose photon-counting CT with spectral shaping via tin prefiltration. MATERIAL AND METHODS: Employing a first-generation photon-counting CT, eight cadaveric specimens were examined with an established three-level scan protocol (hip: Sn 140, knee: Sn 100, ankle: Sn 100 kVp). In three body donors with unilateral knee endoprostheses, additional modified settings were applied (Sn 140 kVp at knee level). Protocols were executed with three dose levels (hip-knee-ankle, high-quality: 5.0-3.0-2.0 mGy, low-dose: 0.80-0.30-0.26 mGy, ultra-low-dose: 0.25-0.06-0.06 mGy). Six radiologists performed torsion analyses, additionally reporting their diagnostic confidence. Intraclass correlation coefficients (ICC) were calculated to assess interrater reliability. RESULTS: No significant differences were ascertained for femoral (p = 0.330), tibial (p = 0.177), and overall leg rotation measurements (p = 0.358) among high-quality, low-dose, and ultra-low-dose protocols. Interrater reliability was excellent for torsion of the femur (ICC 0.915, 95% confidence interval 0.871-0.947), tibia (0.960, 0.938-0.976), and overall leg (0.967, 0.945-0.981). In specimens with total knee endoprostheses, absolute rotational measurements were unaffected by dose level and tube voltage despite superior diagnostic confidence on the ipsilateral and contralateral sides with modified settings (p < 0.001). CONCLUSIONS: Combining the advantages of photon-counting CT and spectral shaping, reliable leg torsion analyses are feasible with ultra-low radiation exposure even in the presence of total knee endoprostheses.

The AMADEUS score is not a sufficient predictor for functional outcome after autologous chondrocyte implantation (ACI) of the knee: data from the German Cartilage Registry (KnorpelRegister DGOU).

INTRODUCTION: The AMADEUS (Area Measurement And DEpth and Underlying Structures) score has advanced to a commonly used tool for MRI-based chondral defect severity grading prior to cartilage knee surgery. It was the intention of this study to assess the AMADEUS for a potential correlation with clinical data by patient-reported outcome measures (PROMs). METHODS: A total of 51 patients undergoing ACI (autologous chondrocyte implantation) between 2016 and 2022 were found eligible and retrospectively analyzed. All patients were registered in the German Cartilage Registry prior to surgery and follow-up data were collected using the Knee Osteoarthritis Outcome score (KOOS), the International Knee Documentation Committee (IKDC) Form and the numeric rating scale (NRS). Pre-operative MRI images were scored by three raters using the AMADEUS classification system, and an overall AMADEUS score was calculated which was subsequently correlated with pre- and post-operative PROMs. RESULTS: Mean patient age was 32.67 ± 8.37 years and mean defect size area 343.04 mm2 ± 139.45 mm2. No correlative capacity of the pre- and postoperative IKDC, KOOS or NRS scores was found with the AMADEUS final score or any of its subscores. From the pre- to postoperative visit, a significant improvement of the PROMs (IKDC: 45.53 ± 21.00 vs. 59.83 ± 17.93, p = 0.04; KOOS Pain: 58.00 ± 16.70 vs. 76.06 ± 19.20, p = 0.03; KOOS ADL: 64.17 ± 18.76 vs. 82.11 ± 16.68, p < 0.01; KOOS Sports: 26.11 ± 18.52 vs. 50.56 ± 23.94, p = 0.01; KOOS QOL: 25.50 ± 14.26 ± 45.28 ± 19.03, p = 0.00) was found. Intraclass correlation coefficients showed an overall good interrater agreement for the AMADEUS total score (ICC = 0.75). CONCLUSIONS: Study results suggest no correlative capacity of the AMADEUS with routinely used PROMs in patients undergoing ACI. Therefore, radiographically assessed cartilage defect characteristics poorly translate to pre- and postoperative patient-reported outcome data.

MRI-Based Evaluation of the Flexor Digitorum Superficialis Anatomy: Investigating the Prevalence and Morphometry of the "Chiasma Antebrachii".

Recent dissection studies resulted in the introduction of the term "chiasma antebrachii", which represents an intersection of the flexor digitorum superficialis (FDS) tendons for digits 2 and 3 in the distal third of the forearm. This retrospective investigation aimed to provide an MRI-based morphologic analysis of the chiasma antebrachii. In 89 patients (41 women, 39.3 ± 21.3 years), MRI examinations of the forearm (2010-2021) were reviewed by two radiologists, who evaluated all studies for the presence and length of the chiasma as well as its distance from the distal radioulnar and elbow joint. The chiasma antebrachii was identified in the distal third of the forearm in 88 patients (98.9%), while one intersection was located more proximally in the middle part. The chiasma had a median length of 28 mm (interquartile range: 24-35 mm). Its distances to the distal radioulnar and elbow joint were 16 mm (8-25 mm) and 215 mm (187-227 mm), respectively. T1-weighted post-contrast sequences were found to be superior to T2- or proton-density-weighted sequences in 71 cases (79.8%). To conclude, the chiasma antebrachii is part of the standard FDS anatomy. Knowledge of its morphology is important, e.g., in targeted injections of therapeutics or reconstructive surgery.

Ultra-High-Resolution Photon-Counting Detector CT Arthrography of the Ankle: A Feasibility Study.

This study was designed to investigate the image quality of ultra-high-resolution ankle arthrography employing a photon-counting detector CT. Bilateral arthrograms were acquired in four cadaveric specimens with full-dose (10 mGy) and low-dose (3 mGy) scan protocols. Three convolution kernels with different spatial frequencies were utilized for image reconstruction (ρ50; Br98: 39.0, Br84: 22.6, Br76: 16.5 lp/cm). Seven radiologists subjectively assessed the image quality regarding the depiction of bone, hyaline cartilage, and ligaments. An additional quantitative assessment comprised the measurement of noise and the computation of contrast-to-noise ratios (CNR). While an optimal depiction of bone tissue was achieved with the ultra-sharp Br98 kernel (S ≤ 0.043), the visualization of cartilage improved with lower modulation transfer functions at each dose level (p ≤ 0.014). The interrater reliability ranged from good to excellent for all assessed tissues (intraclass correlation coefficient ≥ 0.805). The noise levels in subcutaneous fat decreased with reduced spatial frequency (p < 0.001). Notably, the low-dose Br76 matched the CNR of the full-dose Br84 (p > 0.999) and superseded Br98 (p < 0.001) in all tissues. Based on the reported results, a photon-counting detector CT arthrography of the ankle with an ultra-high-resolution collimation offers stellar image quality and tissue assessability, improving the evaluation of miniscule anatomical structures. While bone depiction was superior in combination with an ultra-sharp convolution kernel, soft tissue evaluation benefited from employing a lower spatial frequency.

Weight-bearing gantry-free cone-beam CT of the lumbar spine: Image quality analysis and dose efficiency.

PURPOSE: The effect of static forces under load limits the prognostic value of lumbar spine CT in a horizontal position. Using a gantry-free scanner architecture, this study was designed to assess the feasibility of weight-bearing cone-beam CT (CBCT) of the lumbar spine and to establish the most dose-effective combination of scan parameters. METHODS: Eight formalin-fixated cadaveric specimens were examined with a gantry-free CBCT system in upright position with the aid of a dedicated positioning backstop. Cadavers were scanned with eight combinations of tube voltage (102 or 117 kV), detector entrance dose level (high or low), and frame rates (16 or 30 fps). Five radiologists independently analyzed datasets for overall image quality and posterior wall assessability. Additionally, image noise and signal-to-noise ratio (SNR) were compared based on region-of-interest (ROI) measurements in the gluteal muscles. RESULTS: Radiation dose ranged from 6.8 ± 1.6 (117 kV, dose level low, 16 fps) to 24.3 ± 6.3 mGy (102 kV, dose level high, 30 fps). Both image quality and posterior wall assessability were favored with 30 over 16 fps (all p ≤ 0.008). In contrast, both tube voltage (all p > 0.999) and dose level (all p > 0.096) did not significantly impact reader assessment. Image noise decreased considerably with higher frame rates (all p ≤ 0.040), while SNR ranged from 0.56 ± 0.03 to 1.11 ± 0.30 without a significant difference between scan protocols (all p ≥ 0.060). CONCLUSIONS: Employing an optimized scan protocol, weight-bearing gantry-free CBCT of the lumbar spine allows for diagnostic imaging at reasonable radiation dose.

Angiographic Characteristics Associated with Rupture of Small Intracranial Aneurysms.

OBJECTIVE: Contrary to previous assumptions, there is increasing evidence that small intracranial aneurysms carry a relevant risk of rupture. The aim of this study was to identify angiographic characteristics of small ruptured aneurysms ≤7 mm and to evaluate their significance for clinical decision making. METHODS: A total of 385 patients with 149 unruptured and 236 ruptured intracranial aneurysms were retrospectively compared. Two- and three-dimensional digital subtraction angiography was used to determine aneurysm location, various size parameters, angulations, and morphology, as well as parent artery diameter. RESULTS: Aneurysms of the anterior communicating artery, the posterior inferior cerebellar artery, and the internal carotid artery terminus had a significantly increased prevalence among ruptured aneurysms. Ruptured aneurysms were characterized by a significantly larger aneurysm height (area under the curve [AUC] 0.60, P < 0.01) and aneurysm inclination angle (AUC 0.61, P = 0.02) in addition to a smaller dome (AUC 0.44, P = 0.02) and neck width (AUC 0.38, P < 0.01). Calculation of size ratios increases the predictive value for aneurysm rupture, with AUC values of 0.77 for aspect ratio (P < 0.01) and 0.76 for size ratio (P < 0.01). Aneurysm morphology was not a significant factor after multivariable adjustment (P = 0.20). Arterial hypertension was the only clinical risk factor significantly associated with rupture (P < 0.01). CONCLUSIONS: Of the numerous factors associated with aneurysm rupture, we propose aneurysmal location, aspect ratio (cut-off: 1.5), and aneurysm inclination angle as the most important morphological factors for assessing the rupture risk of small aneurysms because these factors have high AUC values and are robust to changes after rupture.

Ultrahigh-Resolution Photon-Counting CT in Cadaveric Fracture Models: Spatial Frequency Is Not Everything.

In this study, the impact of reconstruction sharpness on the visualization of the appendicular skeleton in ultrahigh-resolution (UHR) photon-counting detector (PCD) CT was investigated. Sixteen cadaveric extremities (eight fractured) were examined with a standardized 120 kVp scan protocol (CTDIvol 10 mGy). Images were reconstructed with the sharpest non-UHR kernel (Br76) and all available UHR kernels (Br80 to Br96). Seven radiologists evaluated image quality and fracture assessability. Interrater agreement was assessed with the intraclass correlation coefficient. For quantitative comparisons, signal-to-noise-ratios (SNRs) were calculated. Subjective image quality was best for Br84 (median 1, interquartile range 1-3; p ≤ 0.003). Regarding fracture assessability, no significant difference was ascertained between Br76, Br80 and Br84 (p > 0.999), with inferior ratings for all sharper kernels (p < 0.001). Interrater agreement for image quality (0.795, 0.732-0.848; p < 0.001) and fracture assessability (0.880; 0.842-0.911; p < 0.001) was good. SNR was highest for Br76 (3.4, 3.0-3.9) with no significant difference to Br80 and Br84 (p > 0.999). Br76 and Br80 produced higher SNRs than all kernels sharper than Br84 (p ≤ 0.026). In conclusion, PCD-CT reconstructions with a moderate UHR kernel offer superior image quality for visualizing the appendicular skeleton. Fracture assessability benefits from sharp non-UHR and moderate UHR kernels, while ultra-sharp reconstructions incur augmented image noise.

Quantitative and qualitative image quality assessment in shoulder examinations with a first-generation photon-counting detector CT.

Photon-counting detector (PCD) CT allows for ultra-high-resolution (UHR) examinations of the shoulder without requiring an additional post-patient comb filter to narrow the detector aperture. This study was designed to compare the PCD performance with a high-end energy-integrating detector (EID) CT. Sixteen cadaveric shoulders were examined with both scanners using dose-matched 120 kVp acquisition protocols (low-dose/full-dose: CTDIvol = 5.0/10.0 mGy). Specimens were scanned in UHR mode with the PCD-CT, whereas EID-CT examinations were conducted in accordance with the clinical standard as "non-UHR". Reconstruction of EID data employed the sharpest kernel available for standard-resolution scans (ρ50 = 12.3 lp/cm), while PCD data were reconstructed with both a comparable kernel (11.8 lp/cm) and a sharper dedicated bone kernel (16.5 lp/cm). Six radiologists with 2-9 years of experience in musculoskeletal imaging rated image quality subjectively. Interrater agreement was analyzed by calculation of the intraclass correlation coefficient in a two-way random effects model. Quantitative analyses comprised noise recording and calculating signal-to-noise ratios based on attenuation measurements in bone and soft tissue. Subjective image quality was higher in UHR-PCD-CT than in EID-CT and non-UHR-PCD-CT datasets (all p < 0.001). While low-dose UHR-PCD-CT was considered superior to full-dose non-UHR studies on either scanner (all p < 0.001), ratings of low-dose non-UHR-PCD-CT and full-dose EID-CT examinations did not differ (p > 0.99). Interrater reliability was moderate, indicated by a single measures intraclass correlation coefficient of 0.66 (95% confidence interval: 0.58-0.73; p < 0.001). Image noise was lowest and signal-to-noise ratios were highest in non-UHR-PCD-CT reconstructions at either dose level (p < 0.001). This investigation demonstrates that superior depiction of trabecular microstructure and considerable denoising can be realized without additional radiation dose by employing a PCD for shoulder CT imaging. Allowing for UHR scans without dose penalty, PCD-CT appears as a promising alternative to EID-CT for shoulder trauma assessment in clinical routine.

Artificial-intelligence-enhanced synthetic thick slabs versus standard slices in digital breast tomosynthesis.

OBJECTIVES: Digital breast tomosynthesis (DBT) can provide additional information over mammography, albeit at the cost of prolonged reading time. This study retrospectively investigated the impact of reading enhanced synthetic 6 mm slabs instead of standard 1 mm slices on interpretation time and readers performance in a diagnostic assessment centre. METHODS: Three radiologists (R1-3; 6/4/2 years of breast imaging experience) reviewed 111 diagnostic DBT examinations. Two datasets were interpreted independently for each patient, with one set containing artificial-intelligence-enhanced synthetic 6 mm slabs with 3 mm overlap, while the other set comprised standard 1 mm slices. Blinded to histology and follow-up, readers noted individual BIRADS categories and diagnostic confidence while reading time was recorded. Among the 111 examinations, 70 findings were histopathologically correlated including 56 malignancies. RESULTS: No significant difference was found between BIRADS categories assigned based on 6 mm vs 1 mm datasets (p ≥ 0.317). Diagnostic accuracy was comparable for 6 mm and 1 mm readings (R1: 87.0% vs 87.0%; R2: 86.1% vs 87.0%; R3: 80.0% vs 84.4%; p ≥ 0.125) with high interrater agreement (intraclass correlation coefficient 0.848 vs 0.865). One reader reported higher confidence with 1 mm slices (R1: p = 0.033). Reading time was substantially shorter when interpreting 6 mm slabs compared to 1 mm slices (R1: 33.5 vs 46.2; R2: 49.1 vs 64.8; R3: 39.5 vs 67.2 sec; all p < 0.001). CONCLUSIONS: Artificial-intelligence-enhanced synthetic 6 mm slabs allow for substantial interpretation time reduction in diagnostic DBT without a decrease in reader accuracy. ADVANCES IN KNOWLEDGE: A simplified slab-only protocol instead of 1 mm slices may offset the higher reading time without a loss of diagnosis-relevant image information in first and second readings. Further evaluations are required regarding workflow implications, particularly in screening settings.

Ultrahigh-resolution computed tomography of the cervical spine without dose penalty employing a cadmium-telluride photon-counting detector.

PURPOSE: This cadaveric study compared image quality between a third-generation dual-source CT scanner with energy-integrating detector technology (EID) and a first-generation CT system employing a photon-counting detector (PCD) for the cervical spine in ultrahigh-resolution mode. METHODS: The cervical spine of eight formalin-fixed full-body cadaveric specimens was scanned with both CT systems using 140 kVp scan protocols matched for CTDIvol (full-dose; low-dose; ultralow-dose; 10 mGy; 3 mGy; 1 mGy). Images were reconstructed with 1 mm slice thickness and 0.5 mm increment. Three radiologists rated overall subjective image quality based on an equidistant five-point scale with the intraclass correlation coefficient (ICC) calculated for assessment of interobserver reliability. Contrast-to-noise ratios were calculated individually for bone (CNRbone) and muscle tissue (CNRmuscle) to provide objective criteria of image analysis. RESULTS: Subjective image quality, as well as CNRbone, and CNRmuscle were each superior for PCD-CT compared to EID-CT among dose-matched scan protocol pairs (all p < 0.05). Between full-dose EID-CT and low-dose PCD-CT, subjective image quality was equal (p = 0.903), while superior quantitative results regarding the latter were ascertained (both p < 0.001). Similarly, objective analysis determined higher CNRbone, and CNRmuscle in ultralow-dose PCD-CT compared to low-dose EID-CT (both p < 0.001), while readers considered the image quality of the respective studies comparable (p > 0.99). Interobserver reliability was good, denoted by an ICC of 0.861 (95 % confidence interval: 0.788 - 0.914; p < 0.001). CONCLUSIONS: In cervical spine examinations, both subjective and objective image quality of PCD-CT were superior to EID-CT in comparison of scan protocols with corresponding dose levels, suggesting potential for significantly reducing the radiation exposure without compromising image quality.

The AMADEUS score is not a sufficient predictor for functional outcome after high tibial osteotomy.

PURPOSE: The Area Measurement And Depth Underlying Structures (AMADEUS) classification system has been proposed as a valuable tool for magnetic resonance (MR)-based grading of preoperatively encountered chondral defects of the knee joint. However, the potential relationship of this novel score with clinical data was yet to determine. It was the primary intention of this study to assess the correlative relationship of the AMADEUS with patient reported outcome scores in patients undergoing medial open-wedge high tibial valgus osteotomy (HTO). Furthermore, the arthroscopic ICRS (International Cartilage Repair Society) grade evaluation was tested for correlation with the AMADEUS classification system. METHODS: This retrospective, monocentric study found a total of 70 individuals that were indicated for HTO due to degenerative chondral defects of the medial compartment between 2008 and 2019. A preoperative MR image as well as a pre-osteotomy diagnostic arthroscopy for ICRS grade evaluation was mandatory for all patients. The Knee Osteoarthritis Outcome Score (KOOS) including its five subscale scores (KOOS-ADL, KOOS-QOL, KOOS-Sports, KOOS-Pain, KOOS-Symptoms) was obtained preoperatively and at a mean follow-up of 41.2 ± 26.3 months. Preoperative chondral defects were evaluated using the AMADEUS classification system and the final AMADEUS scores were correlated with the pre- and postoperative KOOS subscale sores. Furthermore, arthroscopic ICRS defect severity was correlated with the AMADEUS classification system. RESULTS: There was a statistically significant correlation between the AMADEUS BME (bone marrow edema) subscore and the KOOS Symptoms subscore at the preoperative visit (r = 0.25, p = 0.04). No statistically significant monotonic association between the AMADEUS total score and the AMADEUS grade with pre- and postoperative KOOS subscale scores were found. Intraoperatively obtained ICRS grade did reveal a moderate correlative relation with the AMADEUS total score and the AMADEUS grade (r = 0.28, p = 0.02). CONCLUSIONS: The novel AMADEUS classification system largely lacks correlative capacity with patient reported outcome measures in patients undergoing HTO. The MR tomographic appearance of bone marrow edema is the only parameter predictive of the clinical outcome at the preoperative visit.

Twin Robotic Gantry-Free Cone-Beam CT in Acute Elbow Trauma.

Background Posttraumatic CT imaging of the elbow can be challenging when patient mobility is limited. Gantry-free cone-beam CT (CBCT) with a twin robotic radiography system offers greater degrees of positioning freedom for three-dimensional elbow scans over gantry-based multidetector CT (MDCT), but studies analyzing their clinical value remain lacking. Purpose To investigate the diagnostic performance of gantry-free CBCT versus two-dimensional radiography in adults and children with acute elbow trauma. Materials and Methods In a retrospective study, consecutive patients with elbow trauma and positioning difficulty in a gantry-based MDCT who underwent three-dimensional elbow imaging with a gantry-free CBCT after radiography were enrolled between January 2021 and April 2022 at a tertiary care university hospital. Imaging data sets were independently analyzed for fracture presence, articular involvement, and multi-fragment injuries by three radiologists. Diagnostic performance was calculated individually with surgical reports serving as the reference standard. Differences between radiography and CBCT were compared with the McNemar test. Diagnostic confidence was estimated subjectively by each reader, and results were compared with the Wilcoxon signed-rank test. Results Elbow examinations of 23 adults and children (mean age ± SD, 49 years ± 23; seven women) were included with individual assessment of humerus, radius, and ulna (69 bones; 36 fractured). Multi-fragmentary fracture patterns and involvement of articular surfaces were ascertained in 28 and 30 bones, respectively. CBCT allowed for similar or higher sensitivity compared with radiography in the assessment of fractures (range for three readers, 94%-100% vs 72%-81%; respectively, P ≤ .06-.008), articular surface involvement (90%-97% vs 73%-87%; P ≤ .25), and multi-fragmentary patterns (96%-96% vs 68%-75%; P ≤ .03). Readers' diagnostic confidence improved considerably with access to CBCT data sets versus radiographs (all P ≤ .001). For CBCT, the median dose-length product was 70.9 mGy · cm, and the volume CT dose index was 4.4 mGy. Conclusion In acute elbow injuries, gantry-free cone-beam CT enabled improved detection of fractures, articular involvement, and multi-fragmentary patterns compared with two-dimensional radiography. Published under a CC BY 4.0 license Online supplemental material is available for this article.

Accuracy of pedicle screw placement using neuronavigation based on intraoperative 3D rotational fluoroscopy in the thoracic and lumbar spine.

INTRODUCTION: In spinal surgery, precise instrumentation is essential. This study aims to evaluate the accuracy of navigated, O-arm-controlled screw positioning in thoracic and lumbar spine instabilities. MATERIALS AND METHODS: Posterior instrumentation procedures between 2010 and 2015 were retrospectively analyzed. Pedicle screws were placed using 3D rotational fluoroscopy and neuronavigation. Accuracy of screw placement was assessed using a 6-grade scoring system. In addition, screw length was analyzed in relation to the vertebral body diameter. Intra- and postoperative revision rates were recorded. RESULTS: Thoracic and lumbar spine surgery was performed in 285 patients. Of 1704 pedicle screws, 1621 (95.1%) showed excellent positioning in 3D rotational fluoroscopy imaging. The lateral rim of either pedicle or vertebral body was protruded in 25 (1.5%) and 28 screws (1.6%), while the midline of the vertebral body was crossed in 8 screws (0.5%). Furthermore, 11 screws each (0.6%) fulfilled the criteria of full lateral and medial displacement. The median relative screw length was 92.6%. Intraoperative revision resulted in excellent positioning in 58 of 71 screws. Follow-up surgery due to missed primary malposition had to be performed for two screws in the same patient. Postsurgical symptom relief was reported in 82.1% of patients, whereas neurological deterioration occurred in 8.9% of cases with neurological follow-up. CONCLUSIONS: Combination of neuronavigation and 3D rotational fluoroscopy control ensures excellent accuracy in pedicle screw positioning. As misplaced screws can be detected reliably and revised intraoperatively, repeated surgery for screw malposition is rarely required.

Tin-filtered 100 kV Ultra-low-dose Abdominal CT for Calculi Detection in the Urinary Tract: A Comparative Study of 510 Cases.

OBJECTIVES: For detection of urinary calculi, unenhanced low-dose computed tomography is the method of choice, outperforming radiography and ultrasound. This retrospective monocentric study aims to compare a clinically established, dedicated low-dose imaging protocol for detection of urinary calculi with an ultra-low-dose protocol employing tin prefiltration at a standardized tube voltage of 100 kVp. METHODS: Two study arms included a total of 510 cases. The "low-dose group" was comprised of 290 individuals (96 women; age 49 ± 16 years; BMI 27.23 ± 5.60 kg/m2). The "ultra-low-dose group" with Sn100 kVp consisted of 220 patients (84 women; age 47 ± 17 years; BMI 26.82 ± 5.62 kg/m2). No significant difference was ascertained for comparison of age (p = 0.132) and BMI (p = 0.207) between cohorts. For quantitative assessment of image quality, image noise was assessed. RESULTS: No significant difference regarding frequency of calculi detection was found between groups (p = 0.596). Compared to the low-dose protocol (3.08 mSv; IQR 2.22-4.02 mSv), effective dose was reduced by 62.35% with the ultra-low-dose protocol employing spectral shaping (1.16 mSv; IQR 0.89-1.54 mSv). Image noise was calculated at 18.90 (IQR 17.39-21.20) for the low-dose protocol and at 18.69 (IQR 17.30-21.62) for the ultra-low-dose spectral shaping protocol. No significant difference was ascertained for comparison between groups (p = 0.793). CONCLUSION: For urinary calculi detection, ultra-low-dose scans utilizing spectral shaping by means of tin prefiltration at 100 kVp allow for considerable dose reduction of up to 62% over conventional low-dose CT without compromising image quality.

Metal artifact reduction in ultra-high-resolution cone-beam CT imaging with a twin robotic X-ray system.

Cone-beam computed tomography (CBCT) has been shown to be a powerful tool for 3D imaging of the appendicular skeleton, allowing for detailed visualization of bone microarchitecture. This study was designed to compare artifacts in the presence of osteosynthetic implants between CBCT and multidetector computed tomography (MDCT) in cadaveric wrist scans. A total of 32 scan protocols with varying tube potential and current were employed: both conventional CBCT and MDCT studies were included with tube voltage ranging from 60 to 140 kVp as well as additional MDCT protocols with dedicated spectral shaping via tin prefiltration. Irrespective of scanner type, all examinations were conducted in ultra-high-resolution (UHR) scan mode. For reconstruction of UHR-CBCT scans an additional iterative metal artifact reduction algorithm was employed, an image correction tool which cannot be used in combination with UHR-MDCT. To compare applied radiation doses between both scanners, the volume computed tomography dose index for a 16 cm phantom (CTDIvol) was evaluated. Images were assessed regarding subjective and objective image quality. Without automatic tube current modulation or tube potential control, radiation doses ranged between 1.3 mGy (with 70 kVp and 50.0 effective mAs) and 75.2 mGy (with 140 kVp and 383.0 effective mAs) in UHR-MDCT. Using the pulsed image acquisition method of the CBCT scanner, CTDIvol ranged between 2.3 mGy (with 60 kVp and 0.6 mean mAs per pulse) and 61.0 mGy (with 133 kVp and 2.5 mean mAs per pulse). In essence, all UHR-CBCT protocols employing a tube potential of 80 kVp or more were found to provide superior overall image quality and artifact reduction compared to UHR-MDCT (all p < .050). Interrater reliability of seven radiologists regarding image quality was substantial for tissue assessment and moderate for artifact assessment with Fleiss kappa of 0.652 (95% confidence interval 0.618-0.686; p < 0.001) and 0.570 (95% confidence interval 0.535-0.606; p < 0.001), respectively. Our results demonstrate that the UHR-CBCT scan mode of a twin robotic X-ray system facilitates excellent visualization of the appendicular skeleton in the presence of metal implants. Achievable image quality and artifact reduction are superior to dose-comparable UHR-MDCT and even MDCT protocols employing spectral shaping with tin prefiltration do not achieve the same level of artifact reduction in adjacent soft tissue.

One-stop-shop CT arthrography of the wrist without subject repositioning by means of gantry-free cone-beam CT.

Modern cone-beam CT systems are capable of ultra-high-resolution 3D imaging in addition to conventional radiography and fluoroscopy. The combination of various imaging functions in a multi-use setup is particularly appealing for musculoskeletal interventions, such as CBCT arthrography (CBCTA). With this study, we aimed to investigate the feasibility of CBCTA of the wrist in a "one-stop-shop" approach with a gantry-free twin robotic scanner that does not require repositioning of subjects. Additionally, the image quality of CBCTA was compared to subsequent arthrograms on a high-end multidetector CT (MDCTA). Fourteen cadaveric wrists received CBCTA with four acquisition protocols. Specimens were then transferred to the CT suite for additional MDCTA. Dose indices ranged between 14.3 mGy (120 kVp/100 effective mAs; full-dose) and 1.0 mGy (70 kVp/41 effective mAs; ultra-low-dose) for MDCTA and between 17.4 mGy (80 kVp/2.5 mAs per pulse; full-dose) and 1.2 mGy (60 kVp/0.5 mAs per pulse; ultra-low-dose) for CBCTA. Subjective image quality assessment for bone, cartilage and ligamentous tissue was performed by seven radiologists. The interrater reliability was assessed by calculation of the intraclass correlation coefficient (ICC) based on a two-way random effects model. Overall image quality of most CBCTA was deemed suitable for diagnostic use in contrast to a considerable amount of non-diagnostic MDCTA examinations (38.8%). The depiction of bone, cartilage and ligaments in MDCTA with any form of dose reduction was inferior to any CBCTA scan with at least 0.6 mAs per pulse (all p < 0.001). Full-dose MDCTA and low-dose CBCTA were of equal quality for bone tissue visualization (p = 0.326), whereas CBCTA allowed for better depiction of ligaments and cartilage (both p < 0.001), despite merely one third of radiation exposure (MDCTA-14.3 mGy vs. CBCTA-4.5 mGy). Moderate to good interrater reliability was ascertained for the assessment all tissues (ICC 0.689-0.756). Overall median examination time for CBCTA was 5.4 min (4.8-7.2 min). This work demonstrates that substantial dose reduction can be achieved in CT arthrography of the wrist while maintaining diagnostic image quality by employing the cone-beam CT mode of a twin robotic X-ray system. The ability of the multi-use X-ray system to switch between fluoroscopy mode and 3D imaging allows for "one-stop-shop" CBCTA in minimal examination time without the need for repositioning.