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Category: Other Introduction/Purpose: Weightbearing CT (WBCT) has been proven to more precisely measure bone position than conventional weightbearing radiographic series (R) and conventional CT (CT). The purpose of this study was to assess the benefit of using WBCT instead of R and/or CT as the standard imaging modality, evaluating image acquisition time, radiation dose, and cost-effectiveness. Methods: All patients who obtained a WBCT as part of standard of care from July 1, 2013 until August 31, 2023 were included in the study. Image acquisition time (T), radiation dose (RD) per patient, and cost-effectiveness were analyzed and compared between the time period using WBCT (yearly average) and the parameters from 2012, i.e. before the availability of WBCT (RCT group). Results: 20,145 WBCT scans were obtained from 9,065 patients (9,056 scans (45%) before treatment; 11,080 scans (55%) at follow-up). On a yearly average, 1,975 WBCTs (bilateral scans) and an additional 11.5 CTs (bilateral feet and ankles) were obtained (WBCT group). In 2012, 1,850 Rs (bilateral feet, dorsoplantar and lateral, metatarsal head skyline view) and 254 CTs were obtained from 885 patients (RCT group). The mean yearly RD was 4.3/4.8uSv for the WBCT/RCT groups (mean difference of 0.5 uSv; a decrease of 10% for the WBCT group; p<.01). Yearly mean T was 115/494 hours in total (3.5/16.0 minutes per patient) for WBCT/RCT groups (mean difference of 379 hours; a 77% decrease for the WBCT group; p<.01). Yearly cost-effectiveness was a mean profit of 55,441/-723 Euro for WBCT/RCT. Conclusion: 20,145 WBCT scans from 9,065 patients over a period of 10.2 years at a foot and ankle department resulted in 10% decreased RD, 77% decreased T, and increased financial profit (65 Euros per patient) for the institution. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Weight-bearing CT (WBCT) has been proven to allow for more precise and valid measurement of bone position (angles) than conventional weight-bearing radiographs (R) and conventional CT without weight-bearing (CT)1. The measurement by hand (MBH) has demonstrated adequate inter- and intraobserver reliability but high time consumption1. Recently, a semi-automatic software-based angular measurement (SAM) has been developed (Disior Ltd, Helsinki, Finland). The purpose of this study was to compare SAM with MBH regarding angles values and time spent for the investigator. Methods: Fifteen bilateral WBCT scans (PedCAT, Curvebeam, Warrington, PA, USA) were randomly extracted from a local institutional database with more than 13,000 scans. Nineteen angles as shown in table 1 were measured with MBH as previously described and with SAM1. SAM includes software generated 3D models with semi-automatic bone specification of tibia, fibula, talus, calcaneus, navicular, cuboid, cuneiforms and metatarsals. The software automatically defines the longitudinal axes of these bones and automatically measures the angles between these axes. The time spent of the investigator for the measurements was recorded (total process MBH and specification of bones for SAM). The software calculation time for SAM was not measured or considered as investigator time spent. The angles and time spent of MBH and SAM were compared (t-test, homoscedatic). Results: Mean age of the subject was 58 years (range, 7-81), 12 (40%) were male. The pathologies were bilateral in 8 (54%), right in 4 (27%) and left in 3 (20%) subjects (23 feet in total) and were specified as follows, ankle osteoarthritis/instability in 6 (26%), Haglund deformity/Achillodynia in 4 (17%), Forefoot deformity in 7 (30%), Charcot arthropathy in 2 (9%), flatfoot in 4 (17%) feet. The angles did not differ between MBH and SAM (Table 1, each p>.05). The time spent for MBH / SAM was 780+-171s / 20+-8 s on average in total for 19 angles and 41+-9s / 1+-0.4 s per angle (p<.01). Conclusion: This is the first study comparing MBH with SAM. SAM shows similar angles as MBH and can be also considered as reliable measurement option. The investigator time spent is 97% lower for SAM (1 s per angle) than for MBH (41 s per angle). SAM is an important step forward for 3D-angle measurement of WBCT. The next desired is fully automatic software-based measurement. References1. Richter M, Seidl B, Zech S, Hahn S. PedCAT for 3D-Imaging in Standing Position Allows for More Accurate Bone Position (Angle) Measurement than Radiographs or CT. Foot Ankle Surg 2014;20:201-7. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Cone Beam Weight Bearing CT (WBCT) is gaining traction, particularly in the foot and ankle, due to the ability to perform natural stance weight bearing 3D scans. However, the resulting wealth of 3D data renders daily clinical use time consuming. Therefore, reliable automatic measurements are indispensable in order to make best use of the technology. The aim of this study was to evaluate a beta-version WBCT artificial intelligence (AI) automatic measurement system for the M1-M2 intermetatarsal angle (IMA), which is applicable in the absence of metallic hardware in the foot and ankle. We hypothesized that automatic measurements would correlate well with human measurements, and that software reproducibility would be better and close to perfect compared to manual measurements. Methods: In this retrospective case-control study, 90 feet were included from patients who underwent WBCT scans during routine follow up: 44 feet (90.9% female, mean age 54 years) with symptomatic hallux valgus (HV), 46 controls (76.1% female, mean age 49 years). Patients were excluded if they had history of surgery or trauma involving the first or second metatarsals, hallux rigidus, or presence of metal in their foot/ankle. IMA was measured manually on Digitally Reconstructed Radiographs (DRR IMA) and automatically with AI software producing auto 2D (ground plane projection) and 3D (multiplanar) measurements. Each IMA DRR was measured by two independent raters twice to calculate intraclass correlation coefficients (ICCs). To assess intrasoftware reliability, AI software measurements were made twice on each dataset. Manual and automatic measurements were compared between HV and control groups. Failures of the AI software to produce a measurement were recorded. Results: Mean values for controls were 8.6° +-1.8° (range, 5°-14°) for the manually measured DRR IMA, 9.3° +-2.8° (range, 3°- 17°) for auto 2D, and 9.2° +-2.6° (range, 3°-16°) for auto 3D IMA measurements. Compared to controls, HV patients demonstrated significantly increased IMA (p<0.0001): 14.2° +-2.7° (range, 8°-21°) for the manually measured DRR IMA, 15.4°+- 4.4° (range, 8°-26°) for auto 2D, and 15.1° +-4.1° (range 8°-28°) for auto 3D IMA measurements. There were strong correlations (r=0.75 and r=0.80) between manual and auto 2D and 3D measurements. Intraobserver and interobserver ICCs for DRR IMA were 0.96 and 0.90, respectively, and the intra-software ICCs for the AI were near 1.0 for both auto 2D and auto 3D IMA. The AI software failed in 32.3% cases. Conclusion: Our results demonstrated strong correlation between a WBCT Artificial Intelligence based automatic measurement for IMA with human measurements, with the ability to distinguish HV from control with close to 100% repeatability. However, the number of failures was still high due to the early stage beta-version of the algorithm tested. While these early results are promising, further developments are warranted in order to improve usability of this tool in daily practice, especially in the presence of metal hardware. [ABSTRACT FROM AUTHOR]