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Rationale and Objectives: To determine the most cost-effective strategy for pelvic bone marrow biopsies., Materials and Methods: A decision analytic model from the health care system perspective for patients with high clinical concern for multiple myeloma (MM) was used to evaluate the incremental cost-effectiveness of three bone marrow core biopsy techniques: computed tomography (CT) guided, and fluoroscopy guided, no-imaging (landmark-based). Model input data on utilities, costs, and probabilities were obtained from comprehensive literature review and expert opinion. Costs were estimated in 2023 U.S. dollars. Primary effectiveness outcome was quality adjusted life years (QALY). Willingness to pay threshold was $100,000 per QALY gained., Results: No-imaging based biopsy was the most cost-effective strategy as it had the highest net monetary benefit ($4218) and lowest overall cost ($92.17). Fluoroscopy guided was excluded secondary to extended dominance. CT guided biopsies were less preferred as it had an incremental cost-effectiveness ratio ($334,043) greater than the willingness to pay threshold. Probabilistic sensitivity analysis found non-imaging based biopsy to be the most cost-effective in 100% of simulations and at all willingness to pay thresholds up to $200,000., Conclusion: No-imaging based biopsy appears to be the most cost-effective strategy for bone marrow core biopsy in patients suspected of MM., Clinical Relevance: No imaging guidance is the preferred strategy, although image-guidance may be required for challenging anatomy. CT image interpretation may be helpful for planning biopsies. Establishing a non-imaging guided biopsy service with greater patient anxiety and pain support may be warranted., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Objective: To determine whether a simulated low-dose metal artifact reduction (MAR) CT technique is comparable with a clinical dose MAR technique for shoulder arthroplasty evaluation., Materials and Methods: Two shoulder arthroplasties in cadavers and 25 shoulder arthroplasties in patients were scanned using a clinical dose (140 kVp, 300 qrmAs); cadavers were also scanned at half dose (140 kVp, 150 qrmAs). Images were reconstructed using a MAR CT algorithm at full dose and a noise-insertion algorithm simulating 50% dose reduction. For the actual and simulated half-dose cadaver scans, differences in SD for regions of interest were assessed, and streak artifact near the arthroplasty was graded by 3 blinded readers. Simulated half-dose scans were compared with full-dose scans in patients by measuring differences in implant position and by comparing readers' grades of periprosthetic osteolysis and muscle atrophy., Results: The mean difference in SD between actual and simulated half-dose methods was 2.42 HU (95% CI [1.4, 3.4]). No differences in streak artifact grades were seen in 13/18 (72.2%) comparisons in cadavers. In patients, differences in implant position measurements were within 1° or 1 mm in 149/150 (99.3%) measurements. The inter-reader agreement rates were nearly identical when readers were using full-dose (77.3% [232/300] for osteolysis and 76.9% [173/225] for muscle atrophy) and simulated half-dose (76.7% [920/1200] for osteolysis and 74.0% [666/900] for muscle atrophy) scans., Conclusion: A simulated half-dose MAR CT technique is comparable both quantitatively and qualitatively with a standard-dose technique for shoulder arthroplasty evaluation, demonstrating that this technique could be used to reduce dose in arthroplasty imaging.

OBJECTIVE. The purpose of this study was to compare a combined dual-energy CT (DECT) and single-energy CT (SECT) metal artifact reduction technique with a SECT metal artifact reduction technique for detecting lesions near an arthroplasty in a phantom model. MATERIALS AND METHODS. Two CT phantoms with a cobalt chromium sphere attached to a titanium rod, simulating an arthroplasty, within a background of soft-tissue attenuation containing spherical lesions (range, 10-20 mm) around the head and stem of different attenuations from the background (range of attenuation, 10-70 HU) were scanned with a single CT scanner individually (unilateral) and together (bilateral) with the following three dose-equivalent techniques: the currently used clinical protocol (140 kVp, 300 Reference mAs); 100 kVp; and DECT (100 kVp and 150 kVp with a tin filter). Three radiologists reviewed the datasets to identify lesions. Nonparametric AUC was estimated for each reader with each technique. Multireader ANOVA was performed to compare AUCs. Multiple-variable logistic regression analysis was used to identify factors affecting sensitivity and specificity. RESULTS. Accuracy was lower ( p < 0.001) for the DECT 130-keV technique than for the 100-, 70-, and 140-kVp techniques. Sensitivity was higher with unilateral arthroplasties ( p = 0.037), with greater contrast differences from background ( p < 0.001), and with the SECT 100-kVp technique versus other techniques ( p < 0.001). The difference in specificities of modalities was not statistically significant ( p = 0.148). CONCLUSION. Combining DECT and SECT techniques does not provide additional benefits for lesion detection as opposed to using SECT alone.

Objective: To determine whether a 3D magnetic resonance imaging (MRI) sequence with postprocessing applied to simulate computed tomography (CT) ("pseudo-CT") images can be used instead of CT to measure acetabular version and alpha angles and to plan for surgery in patients with femoroacetabular impingement (FAI)., Materials and Methods: Four readers retrospectively measured acetabular version and alpha angles on MRI and CT images of 40 hips from 20 consecutive patients (9 female patients, 11 male patients; mean age, 26.0 ± 6.5 years) with FAI. 3D models created from MRI and CT images were assessed by 2 orthopedic surgeons to determine the need for femoroplasty and/or acetabuloplasty. Interchangeability of MRI with CT was tested by comparing agreement between 2 readers using CT (intramodality) with agreement between 1 reader using CT and 1 using MRI (intermodality)., Results: Intramodality and intermodality agreement values were nearly identical for acetabular version and alpha angle measurements and for surgical planning. Increases in inter-reader disagreement for acetabular version angle, alpha angle, and surgical planning when MRI was substituted for CT were - 2.1% (95% confidence interval [CI], - 7.7 to + 3.5%; p = 0.459), - 0.6% (95% CI, - 8.6 to + 7.3%; p = 0.878), and 0% (95% CI, - 15.1 to + 15.1%; p = 1.0), respectively, when an agreement criterion ≤ 5° was used for angle measurements., Conclusion: Pseudo-CT MRI was interchangeable with CT for measuring acetabular version and highly favorable for interchangeability for measuring alpha angle and for surgical planning, suggesting that MRI could replace CT in assessing patients with FAI.

OBJECTIVE. Dual-energy CT (DECT) involves the acquisition of CT attenuation data at two different energy levels. In musculoskeletal imaging, gout detection is the most validated clinical indication for DECT. However, there is emerging evidence for several other clinical musculoskeletal applications, including metal artifact reduction and bone marrow imaging for traumatic, neoplastic, and inflammatory processes. CONCLUSION. In this article, we review the current role of DECT in musculoskeletal imaging, primarily focusing on nongout entities.

Background: Detection of postoperative component position and implant shift following total shoulder arthroplasty (TSA) can be challenging using routine imaging. The purpose of this study was to evaluate glenoid component position over time using 3-dimensional computed tomography (CT) analysis with minimum 2-year follow-up., Methods: Twenty patients underwent primary TSA with sequential CT scanning of the shoulder: a preoperative study, an immediate postoperative study within 2 weeks of surgery, and a postoperative study performed at minimum 2-year follow-up (CT3). Postoperative glenoid component position and central peg osteolysis were assessed across the immediate postoperative CT scan and CT3. Glenoids with evidence of component shift and/or grade 1 central peg osteolysis on CT3 were considered at risk of loosening., Results: Of the patients, 7 (35%) showed evidence of glenoid components at risk of loosening on CT3, 6 with component shift (3 with increased inclination alone, 1 with increased retroversion alone, and 2 with both increased inclination and retroversion). Significantly more patients with glenoid component shift had grade 1 central peg osteolysis on CT3 compared with those without shift (83% vs 7%, P = .002). One clinical failure occurred, with the patient undergoing revision to reverse TSA for rotator cuff deficiency., Conclusions: Three-dimensional CT imaging analysis following TSA identified changes in glenoid component position over time, with inclination being the most common direction of shift and grade 1 central peg osteolysis commonly associated with shift. These findings raise concern for glenoids at risk of loosening, but further follow-up is needed to determine the long-term clinical impact of these findings., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Objective: To determine the diagnostic yield of CT-guided percutaneous biopsy of densely sclerotic bone lesions., Materials and Methods: We retrospectively analyzed CT-guided percutaneous bone biopsies performed at our institution from September 2008 through August 2011 (329 cases) and from September 2012 through August 2015 (324 cases) after adoption of a battery-powered drill system (OnControl). Bone lesions were included in the analysis if they were >70% sclerotic by visual inspection, had a density > 2 times that of adjacent trabecular bone, and had an attenuation of ≥250 HU. Pathological fractures, diskitis-osteomyelitis, and osteoid osteomas were excluded. Eligible cases were characterized by lesion location, maximum lesion diameter, mean density, biopsy needle type and gauge, reported complications, and histological diagnosis. Clinical and imaging follow-up was used to confirm histological diagnosis. Cases in which a benign histological diagnosis could not be confirmed by imaging over a minimum period of 1 year were excluded., Results: A total of 37 biopsies of sclerotic bone lesions met the inclusion criteria, 17 of which were performed with a power drill needle and 20 of which were performed with a manually driven needle. The mean lesion density was 604.1 HU. The overall diagnostic yield was 78.4%; overall diagnostic accuracy was 94.6%, and the false-negative rate was 5.4%. Diagnostic yield and accuracy were 82.4% and 100% respectively, with a power drill and 75% and 90% respectively, with a manual device. Diagnostic yield for lesions ≥700 HU was 90% (9 out of 10)., Conclusion: Densely sclerotic bone lesions are amenable to percutaneous needle biopsy.

Objective: The objective of this study was to compare reader accuracy detecting lesions near hardware in a CT phantom model at different radiation exposures using an advanced metal artifact reduction (MAR) algorithm and standard filtered back projection (FBP) techniques and to determine if radiation exposure could be decreased using MAR without compromising lesion detectability., Materials and Methods: A CT phantom manufactured with spherical lesions of various sizes (10-20 mm) and attenuations (20-50 HU) embedded around cobalt-chromium spheres attached to titanium rods, simulating an arthroplasty, was scanned on a single CT scanner (FLASH, Siemens Healthcare) at 140 kVp and 0.6-mm collimation using clinical-dose (300 Quality Reference mAs [Siemens Healthcare]), low-dose (150 Quality Reference mAs), and high-dose (600 Quality Reference mAs) protocols. Images reconstructed with iterative MAR, advanced modeled iterative reconstruction (ADMIRE), and FBP with identical parameters were anonymized and independently reviewed by three radiologists. Accuracies for detecting lesions, measured as AUC, sensitivity, and specificity, were compared., Results: Accuracy using MAR was significantly higher than that using FBP at all exposures (p values ranged from < 0.001 to 0.021). Sensitivity was also higher for MAR than for FBP at all exposures. Specificity was very high for both reconstruction techniques at all exposures with no significant differences. Accuracy of low-dose MAR was higher than and not inferior to standard-dose and high-dose FBP. MAR was significantly more sensitive than FBP in detecting smaller lesions (p = 0.021) and lesions near high streak artifact (p < 0.001)., Conclusion: MAR improves reader accuracy to detect lesions near hardware and allows significant reductions in radiation exposure without compromising accuracy compared with FBP in a CT phantom model.

The purpose of this study was to demonstrate feasibility of a clinical CT imaging and analysis technique to quantify regional variations in trabecular bone architecture and mineralization of glenoid bones. Specifically, our objective was to determine to what extent clinical CT imaging of intact upper extremities can describe variations of trabecular bone architectures at anatomic and peri-implant regions by comparing trabecular bone architectures as measured by high-resolution, micro CT imaging of same excised glenoid bones. Bone volume fraction (BVF), trabecular bone thickness (TbTh), number of trabecular bone (TbN), spacing (TbS), pattern factor (TbPf), bone surface area (BSA), and skeletal connectivity (Conn.), in addition to bone mineral content (BMC) and bone mineral density (BMD), were quantified from both clinical and micro CT images using whole bone, anatomic, and peri-implant bone masks. Strong correlations of BVF, TbTh, TbSp, BMC, and BMD were found between clinical CT and micro CT imaging methods. The variations in BVF, TbTh, TbSp, TbN, BMC, and BMD at anatomical and peri-implant regions were larger than those at whole bone regions. In this study, we have demonstrated that this clinical CT imaging methodology can be used to quantify variations of a patient's glenoid bone at anatomic and peri-implant levels. Statement of Clinical Significance. An in vivo quantitative assessment of glenoid trabecular bone architecture in the anatomic and peri-implant regions may improve our understanding on the role of bone quality on glenoid component loosening following total shoulder arthroplasty. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:85-96, 2018., (© 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Objective: The purpose of this study was to compare iterative metal artifact reduction (iMAR), a new single-energy metal artifact reduction technique, with filtered back projection (FBP) in terms of attenuation values, qualitative image quality, and streak artifacts near shoulder and hip arthroplasties and observer ability with these techniques to detect pathologic lesions near an arthroplasty in a phantom model., Materials and Methods: Preoperative and postoperative CT scans of 40 shoulder and 21 hip arthroplasties were reviewed. All postoperative scans were obtained using the same technique (140 kVp, 300 quality reference mAs, 128 × 0.6 mm detector collimation) on one of three CT scanners and reconstructed with FBP and iMAR. The attenuation differences in bones and soft tissues between preoperative and postoperative scans at the same location were compared; image quality and streak artifact for both reconstructions were qualitatively graded by two blinded readers. Observer ability and confidence to detect lesions near an arthroplasty in a phantom model were graded., Results: For both readers, iMAR had more accurate attenuation values (p < 0.001), qualitatively better image quality (p < 0.001), and less streak artifact (p < 0.001) in all locations near arthroplasties compared with FBP. Both readers detected more lesions (p ≤ 0.04) with higher confidence (p ≤ 0.01) with iMAR than with FBP in the phantom model., Conclusion: The iMAR technique provided more accurate attenuation values, better image quality, and less streak artifact near hip and shoulder arthroplasties than FBP; iMAR also increased observer ability and confidence to detect pathologic lesions near arthroplasties in a phantom model.

An increasing number of joint replacements are being performed in the United States. Patients undergoing these procedures can have various complications. Imaging is one of the primary means of diagnosing these complications. Cross-sectional imaging techniques, such as computed tomography (CT) and MR imaging, are more sensitive than radiographs for evaluating complications. The use of CT and MR imaging in patients with metallic implants is limited by the presence of artifacts. This review discusses the causes of metal artifacts on MR imaging and CT, contributing factors, and conventional and novel methods to reduce the effects of these artifacts on scans., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Preoperative quantitative assessment of glenoid bone loss, selection of the glenoid component, and definition of its desired location can be challenging. Placement of the glenoid component in the desired location at the time of surgery is difficult, especially with severe glenoid pathological conditions., Methods: Forty-six patients were randomly assigned to three-dimensional computed tomographic preoperative templating with either standard instrumentation or with patient-specific instrumentation and were compared with a nonrandomized group of seventeen patients with two-dimensional imaging and standard instrumentation used as historical controls. All patients had postoperative three-dimensional computed tomographic metal artifact reduction imaging to measure and to compare implant position with the preoperative plan., Results: Using three-dimensional imaging and templating with or without patient-specific instrumentation, there was a significant improvement achieving the desired implant position within 5° of inclination or 10° of version when compared with two-dimensional imaging and standard instrumentation., Conclusion: Three-dimensional assessment of glenoid anatomy and implant templating and the use of these images at the time of surgery improve the surgeon's ability to place the glenoid implant in the desired location., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Objective: Iterative metal artifact reduction (IMAR) is a sinogram inpainting technique that incorporates high-frequency data from standard weighted filtered back projection (WFBP) reconstructions to reduce metal artifact on computed tomography (CT). This study was designed to compare the image quality of IMAR and WFBP in total shoulder arthroplasties (TSA); determine the optimal amount of WFBP high-frequency data needed for IMAR; and compare image quality of the standard 3D technique with that of a faster 2D technique., Materials and Methods: Eight patients with nine TSA underwent CT with standardized parameters: 140 kVp, 300 mAs, 0.6 mm collimation and slice thickness, and B30 kernel. WFBP, three 3D IMAR algorithms with different amounts of WFBP high-frequency data (IMARlo, lowest; IMARmod, moderate; IMARhi, highest), and one 2D IMAR algorithm were reconstructed. Differences in attenuation near hardware and away from hardware were measured and compared using repeated measures ANOVA. Five readers independently graded image quality; scores were compared using Friedman's test., Results: Attenuation differences were smaller with all 3D IMAR techniques than with WFBP (p < 0.0063). With increasing high-frequency data, the attenuation difference increased slightly (differences not statistically significant). All readers ranked IMARmod and IMARhi more favorably than WFBP (p < 0.05), with IMARmod ranked highest for most structures. The attenuation difference was slightly higher with 2D than with 3D IMAR, with no significant reader preference for 3D over 2D., Conclusions: IMAR significantly decreases metal artifact compared to WFBP both objectively and subjectively in TSA. The incorporation of a moderate amount of WFBP high-frequency data and use of a 2D reconstruction technique optimize image quality and allow for relatively short reconstruction times.

Rationale and Objectives: New tests are typically assessed by estimating their technical and diagnostic performance through comparisons with a reference standard. A valid reference standard, however, is not always available and is not required for assessing the interchangeability of a new test with an existing one., Materials and Methods: To show interchangeability of a new test with an existing test, one compares the differences in diagnoses between the new and existing tests to differences between diagnoses made with the existing test on several occasions. We illustrate the test for interchangeability with two studies. In a transcatheter aortic valve replacement study, we test whether semiautomated analysis can be used interchangeably with manual reconstructions from three-dimensional computed tomography (CT) images. In patients with femoroacetabular impingement, we test whether magnetic resonance imaging (MRI) can replace CT to measure acetabular version., Results: Although the semiautomated method agreed often with the manual measurement of aortic valve size (87.6%), interchanging the semiautomated method with manual measurements by an expert would lead to a 1.7%-12.2% increase in the frequency of disagreement. Interchanging MRI for CT to measure acetabular version would lead to differences in angle measurements of 2.0° to 3.1° in excess of the differences we would expect to see with CT alone., Conclusions: Testing for agreement or correlation between a new and an existing test is not sufficient evidence of the performance of a new test. A formal evaluation of interchangeability can be conducted in the absence of a reference standard., (Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to optimize CT arthrography technique and determine if dual energy CT (DECT) can provide any benefit over single energy CT (SECT). Iodinated contrast attenuation at different concentrations was measured using DECT and SECT at different beam energies (140, 120, and 80 kVp). Dose and noise were measured on phantoms at different tube currents. Three bovine femoral condyles with artificially created cartilage defects were scanned with dose-equivalent protocols. Contrast-to-noise ratio (CNR) between cartilage and iodine was measured, and the appearance of cartilage defects was graded by two readers. DECT scans were post-processed for iodine quantification. The beam energy 80 kVp had the highest iodine signal, 50% greater than DECT, 75% greater than 120 kVp, and 100% greater than 140 kVp. Noise was nearly identical for all techniques when dose was matched. The 80 kVp level had the highest CNR, 25% higher than 120 kVp and DECT, and 33% greater than 140 kVp. The 80 kVp technique was also preferred by both readers. DECT iodine quantification was significantly limited by the post-processing application, noise, and beam hardening. In this in-vitro study, the SECT 80 kVp CT arthrography technique was superior to currently performed 120 and 140 kVP SECT techniques and DECT.

Hypothesis: Humeral version is highly variable in human beings. Accurate assessment of humeral version may allow for more anatomic reconstruction at shoulder arthroplasty. Two-dimensional (2D) computed tomography (CT) has been used to measure humeral version but has limitations of poor interobserver reproducibility and strict dependence on arm positioning during image acquisition. This study evaluated a new technique, 3-dimensional (3D) volume rendering, for measuring humeral version., Materials and Methods: Eight dried human humerus specimens were included in the study. Gold standard measurements of humeral version were obtained by use of metallic beads and fluoroscopy. The specimens were then scanned at CT in 2 different positions, 1 neutral to the table and 1 angled at 20 degrees . The image data sets were used to measure humeral version in each bone with both the standard 2D technique and the new 3D technique. Measurements were performed by 3 readers at 2 different time points. Readers were blinded to the gold standard results and each others' measurements., Results: For all readers, 3D measurements averaged within 4.3 degrees of the gold standard. For 2 of the 3 readers, 3D measurements were more accurate than 2D measurements. For all 3 readers, intraobserver variability was better with the 3D technique. For all reader pairs, interobserver variability was better with the 3D technique., Conclusions: This study shows a 3D volume-rendering CT technique to measure humeral version accurately and consistently that is independent of patient positioning., ((c) 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

The role of 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in combination with computed tomography (CT) in the evaluation of pelvic malignancies has been rapidly growing in recent years. FDG PET has proved to be valuable in the evaluation of a variety of pelvic malignancies, including colorectal cancer, uterine cervical cancer, ovarian cancer, endometrial cancer, and non-Hodgkin lymphoma. However, a number of pitfalls are commonly encountered at FDG PET, including normal physiologic activity in bowel, ovaries, endometrium, and blood vessels and focal retained activity in ureters, bladder diverticula, pelvic kidneys, and urinary diversions. The use of an in-line FDG PET-CT system, with special attention given to proper patient preparation and scanning protocol, often provides valuable information to help localize and define disease and avoid potential diagnostic pitfalls.

Nephrogenic rests (NR) are persistent benign remnants of embryonic renal tissue. A small percentage of these may develop into Wilms' tumor (WT). Radiologic imaging is relied upon to differentiate between these entities, with the hallmark of malignant transformation being growth on serial imaging studies. There is, however, considerable overlap in their imaging characteristics. The authors present a case of two biopsy-proven NR in a 2-year-old girl with sporadic aniridia that were indistinguishable from WT on initial radiologic studies. One of the NR grew on serial imaging studies mimicking a WT, but after resection was confirmed to be a benign hyperplastic NR on pathologic examination.