Combined evaluation of blood flow and tissue perfusion in diabetic feet by intra-arterial dynamic 4DCT imaging.

Critical limb ischemia is associated with high mortality and major amputations. Intra-arterial digital subtraction angiography (IADSA) has been the reference standard but has some shortcomings including the two-dimensional projection and the lack of tissue perfusion information. The aim of this exploratory study is to examine four-dimensional computed tomography (4DCT) angiography and perfusion imaging using low-volume intra-arterial contrast injections for an improved anatomic and hemodynamic assessment in patients with foot ulcers. Three patients underwent a low-volume (2 mL) intra-arterial contrast-enhanced 4DCT examination combined with a diagnostic IADSA. An automated assessment of blood flow and tissue perfusion from the 4DCT data was performed. Vascular structures and corresponding blood flows were successfully assessed and correlated well with the IADSA results. Perfusion values of the affected tissue were significantly higher compared to the unaffected tissue. The proposed 4DCT protocol combined with the minimal usage of contrast agent (2 mL) provides superior images compared to IADSA as three phases (arterial, perfusion, and venous) are captured. The obtained parameters could allow for an improved diagnosis of critical limb ischemia as both the proximal vasculature and the extent of the perfusion deficit in the microvasculature can be assessed.Relevance statementIntra-arterial 4DCT allows for assessing three phases (arterial, perfusion and venous) using minimal contrast (2 mL). This method could lead to an improved diagnosis of critical limb ischemia as both proximal vasculature and the extent of the perfusion deficit are assessed.Trial registrationISRCTN, ISRCTN95737449. Registered 14 March 2023-retrospectively registered, https://www.isrctn.com/ISRCTN95737449 Key points• Three phases (arterial, perfusion, and venous) are obtained from 2 mL intra-arterial 4DCT.• The obtained hemodynamic parameters correlated well with the IADSA findings.• 4DCT surpassed IADSA in terms of assessment of venous blood flow and inflammatory hyperperfusion.• The assessment of tissue perfusion could lead to optimizing the revascularization strategy.

Differentiation between Angiomatous Meningioma and Solitary Fibrous Tumors.

Teaching point: The presence of intralesional calcifications, a dural tail sign, adjacent hyperostosis, and early draining veins can help distinguish angiomatous meningiomas (AM) from solitary fibrous tumors (SFT).

Fast full-field modulation transfer function analysis for photographic lens quality assessment.

Full-field modulation transfer function (MTF) data based on the slanted-edge method can give useful insights on the performance of a photographic lens sample and its shortcomings. Decentering and other out-of-tolerance states are recognized easily. A process to derive accurate lens MTF from slanted-edge spatial frequency response measurements is presented, covering chart design and alignment, data capture by standard digital cameras, slanted-edge algorithm implementation requirements, sensor and chart MTF corrections, and also visualization of the results. It is demonstrated that the reliability of the measured MTF values is by far good enough to support automated quality assessment with a measurement accuracy of ≈0.02 MTF and repeatability of ≲0.005 up to 100 c/mm. The measured full-field MTF values provide an unambiguous numerical criterion for comparison with expectations based on lens design.

Geniculate Artery Embolization in Patients With Recurrent Hemarthrosis After Knee Arthroplasty: A Retrospective Study.

BACKGROUND: Recurrent hemarthrosis after knee arthroplasty is an uncommon and disabling complication of this frequently performed procedure. Selective endovascular embolization of the geniculate arteries is one of the therapeutic options to manage this complication. The purpose of this study is to analyze the effectiveness of this treatment in patients suffering from recurrent hemarthrosis after knee arthroplasty. METHODS: We performed a retrospective study of 31 patients (39 embolization procedures) with recurrent hemarthrosis after knee arthroplasty. There were 17 men and 14 women with a median age of 67 years (range 48-90). All patients were referred for geniculate artery embolization between January 2007 and November 2016. RESULTS: Twenty-seven procedures were executed on the right side and 12 on the left side. Total knee arthroplasty was performed on 29 patients, only 2 patients underwent unicompartmental knee arthroplasty. Embolization of the superior geniculate arteries was achieved in all patients. In 12 of 39 procedures (31%), at least 1 of the inferior geniculate arteries could not be catheterized, therefore embolization was achieved through collaterals. Symptomatic improvement was observed in 26 of 31 patients (84%). Discomfort or mild postprocedural pain was observed in most patients, needing only minor pain medication, mostly resolving within 24 hours. Two patients presented with a severe complication: a 48-year-old male patient developed septic arthritis and an 85-year-old hypertensive female patient treated with anticoagulants showed aseptic necrosis of the femoral condyles. CONCLUSION: Embolization of geniculate arteries is a safe and effective treatment in recurrent hemarthrosis post knee arthroplasty. Clinical improvement was seen in most patients.

Comparison of MTF measurements using edge method: towards reference data set.

A sensor's spatial resolution has traditionally been a difficult concept to define, but all would agree that it is inextricably linked to the Ground Sampling Distance (GSD) and Instantaneous Field of View (IFOV) of an imaging sensor system. As a measure of the geospatial quality of imagery, the Modulation Transfer Function (MTF) of the system is often used along with the signal-to-noise ratio (SNR). However, their calculation is not fully standardized. Further, consistent measurements and comparisons are often hard to obtain. Therefore, in the Infrared and Visible Optical Sensors (IVOS) subgroup of the Working Group on Calibration Validation (WGCV) of the Committee for Earth Observation Satellites (CEOS), a team from various countries and professional entities who are involved in MTF measurement was established to address the issue of on-orbit MTF measurements and comparisons. As a first step, a blind comparison of MTF measurements based on the slanted edge approach has been undertaken. A set of both artificial and actual satellite edge images was developed and a first comparison of processing results was generated. In all, seven organizations contributed to the experiment and several significant results were generated in 2016. No single participant produced the best results for all test images as measured by either the closest to the mean result, or closest to the truth for the synthetic test images. In addition, close estimates of the MTF value at Nyquist did not ensure the accuracy of other MTF values at other spatial frequencies. Some algorithm results showed that the accuracy of their estimates depended upon the type of MTF curve that was being analyzed. After the initial analysis, participants were allowed to modify their methodology and reprocess the test images since, in several cases, the results contained errors. Results from the second iteration, in 2017, verified that the anomalies in the experiment's first iteration were due to errors in either coding or methodology, or both. One organization implemented a third trial to fix software errors. This emphasizes the importance of fully understanding both methodology and implementation, in order to ensure accurate and repeatable results. To extend this comparison study, a reference data set, which is composed of edge images and corresponding MTF curves, will be built. A broader audience will be able to access the edge images through the CEOS CalVal Portal (http://calvalportal.ceos.org/). This paper, which is associated with the reference data set, can serve as a new tool to either implement or check, or both, the MTF measurement that relies on the slanted edge method.