Anna L. Falkowski

Bio: Anna L. Falkowski is an academic researcher from University Hospital of Basel. The author has contributed to research in topics: Medicine & Magnetic resonance imaging. The author has an hindex of 10, co-authored 27 publications receiving 324 citations. Previous affiliations of Anna L. Falkowski include University of Michigan & University of Basel.

Initial Results of a Single-Source Dual-Energy Computed Tomography Technique Using a Split-Filter: Assessment of Image Quality, Radiation Dose, and Accuracy of Dual-Energy Applications in an In Vitro and In Vivo Study.

Abstract: OBJECTIVE The aim of this study was to investigate the image quality, radiation dose, and accuracy of virtual noncontrast images and iodine quantification of split-filter dual-energy computed tomography (CT) using a single x-ray source in a phantom and patient study. MATERIALS AND METHODS In a phantom study, objective image quality and accuracy of iodine quantification were evaluated for the split-filter dual-energy mode using a tin and gold filter. In a patient study, objective image quality and radiation dose were compared in thoracoabdominal CT of 50 patients between the standard single-energy and split-filter dual-energy mode. The radiation dose was estimated by size-specific dose estimate. To evaluate the accuracy of virtual noncontrast imaging, attenuation measurements in the liver, spleen, and muscle were compared between a true noncontrast premonitoring scan and the virtual noncontrast images of the dual-energy scans. Descriptive statistics and the Mann-Whitney U test were used. RESULTS In the phantom study, differences between the real and measured iodine concentration ranged from 2.2% to 21.4%. In the patient study, the single-energy and dual-energy protocols resulted in similar image noise (7.4 vs 7.1 HU, respectively; P = 0.43) and parenchymal contrast-to-noise ratio (CNR) values for the liver (29.2 vs 28.5, respectively; P = 0.88). However, the vascular CNR value for the single-energy protocol was significantly higher than for the dual-energy protocol (10.0 vs 7.1, respectively; P = 0.006). The difference in the measured attenuation between the true and the virtual noncontrast images ranged from 3.1 to 6.7 HU. The size-specific dose estimate of the dual-energy protocol was, on average, 17% lower than that of the single-energy protocol (11.7 vs 9.7 mGy, respectively; P = 0.008). CONCLUSIONS Split-filter dual-energy compared with single-energy CT results in similar objective image noise in addition to dual-energy capabilities at 17% lower radiation dose. Because of beam hardening, split-filter dual-energy can lead to decreased CNR values of iodinated structures.

4D-SPECT/CT in orthopaedics: a new method of combined quantitative volumetric 3D analysis of SPECT/CT tracer uptake and component position measurements in patients after total knee arthroplasty

Abstract: Objective The purpose was to evaluate the intra- and inter-observer reliability of combined quantitative 3D-volumetric single-photon emission computed tomography (SPECT)/CT analysis including size, intensity and localisation of tracer uptake regions and total knee arthroplasty (TKA) position.

Comparison of image quality and radiation dose between split-filter dual-energy images and single-energy images in single-source abdominal CT.

Abstract: To compare image quality and radiation dose of abdominal split-filter dual-energy CT (SF-DECT) combined with monoenergetic imaging to single-energy CT (SECT) with automatic tube voltage selection (ATVS). Two-hundred single-source abdominal CT scans were performed as SECT with ATVS (n = 100) and SF-DECT (n = 100). SF-DECT scans were reconstructed and subdivided into composed images (SF-CI) and monoenergetic images at 55 keV (SF-MI). Objective and subjective image quality were compared among single-energy images (SEI), SF-CI and SF-MI. CNR and FOM were separately calculated for the liver (e.g. CNRliv) and the portal vein (CNRpv). Radiation dose was compared using size-specific dose estimate (SSDE). Results of the three groups were compared using non-parametric tests. Image noise of SF-CI was 18% lower compared to SEI and 48% lower compared to SF-MI (p 0.628). Subjective sharpness was equal between single-energy and monoenergetic images and diagnostic confidence was equal between single-energy and composed images. FOMliv was highest for SF-CI. FOMpv was equal for SEI and SF-MI (p = 0.78). SSDE was significant lower for SF-DECT compared to SECT (p < 0.022). The combined use of split-filter dual-energy CT images provides comparable objective and subjective image quality at lower radiation dose compared to single-energy CT with ATVS. • Split-filter dual-energy results in 18% lower noise compared to single-energy with ATVS. • Split-filter dual-energy results in 11% lower SSDE compared to single-energy with ATVS. • Spectral shaping of split-filter dual-energy leads to an increased dose-efficiency.

Do Chondral Lesions of the Knee Correlate with Bone Tracer Uptake by Using SPECT/CT?

Abstract: Chondral lesions with osseous involvement represented by grades 3 and 4 showed higher SPECT/CT bone tracer uptake than those without osseous involvement (grades 1 and 2).

Isolated pancreatic tuberculosis: A case report and radiological comparison with cystic pancreatic lesions

Abstract: Pancreatic tuberculosis is rare and can occur in the absence of evidence of tuberculosis elsewhere in the body. Here we review the radiological appearance of pancreatic tuberculosis and compare it with other cystic pancreatic lesions, including common lesions (pseudocysts, serous or mucinous cystadenomas, intraductal papillary mucinous neoplasm) and rare lesions such as solid pseudopapillary tumors, etc. Their typical localizations within the pancreas and their malignant potential are presented. Knowledge of these can assist radiologists and clinicians in selecting the best approach towards making the correct diagnosis.

Orthopaedic biofilm infections

Abstract: Many infections of the musculoskeletal system are biofilm infections that develop on non-living surfaces. Microorganisms adhere either on dead bone (sequesters) or implants. As a rule for a curative concept, chronic osteomyelitis or implant-associated bone infection must be treated with a combination of surgery and antimicrobial therapy. If an implant is kept in place, or a new device is implanted before complete healing of infection, a biofilm-active antibiotic should be used. Rifamycins are active against biofilms of staphylococci, and fluoroquinolones against those of Gram-negative bacilli. In this review, the management of chronic osteomyelitis, periprosthetic joint infection and implant-associated osteomyelitis of long bones is presented.

Intermanufacturer Comparison of Dual-Energy CT Iodine Quantification and Monochromatic Attenuation: A Phantom Study.

Abstract: Purpose To determine the accuracy of dual-energy computed tomographic (CT) quantitation in a phantom system comparing fast kilovolt peak-switching, dual-source, split-filter, sequential-scanning, and dual-layer detector systems. Materials and Methods A large elliptical phantom containing iodine (2, 5, and 15 mg/mL), simulated contrast material-enhanced blood, and soft-tissue inserts with known elemental compositions was scanned three to five times with seven dual-energy CT systems and a total of 10 kilovolt peak settings. Monochromatic images (50, 70, and 140 keV) and iodine concentration images were created. Mean iodine concentration and monochromatic attenuation for each insert and reconstruction energy level were recorded. Measurement bias was assessed by using the sum of the mean signed errors measured across relevant inserts for each monochromatic energy level and iodine concentration. Iodine and monochromatic errors were assessed by using the root sum of the squared error of all measurements. Results At least one acquisition paradigm per scanner had iodine biases (range, -2.6 to 1.5 mg/mL) with significant differences from zero. There were no significant differences in iodine error (range, 0.44-1.70 mg/mL) among the top five acquisition paradigms (one fast kilovolt peak switching, three dual source, and one sequential scanning). Monochromatic bias was smallest for 70 keV (-12.7 to 15.8 HU) and largest for 50 keV (-80.6 to 35.2 HU). There were no significant differences in monochromatic error (range, 11.4-52.0 HU) among the top three acquisition paradigms (one dual source and two fast kilovolt peak switching). The lowest accuracy for both measures was with a split-filter system. Conclusion Iodine and monochromatic accuracy varies among systems, but dual-source and fast kilovolt-switching generally provided the most accurate results in a large phantom. © RSNA, 2017 Online supplemental material is available for this article.