MRI of Soft-Tissue Tumors: What to Include in the Report

MRI serves as a critical step in the workup, local staging, and treatment planning of extremity soft-tissue masses. For the radiologist to meaningfully contribute to the management of soft-tissue masses, they need to provide a detailed list of descriptors of the lesion outlined in an organized report. While it is occasionally possible to use MRI to provide a diagnosis for patients with a mass, it is more often used to help with determining the differential diagnosis and planning of biopsies, surgery, radiation treatment, and chemotherapy (when provided). Each descriptor on the list outlined in this article is specifically aimed to assist in one or more facets of the overall approach to soft-tissue masses. This applies to all masses, but in particular sarcomas. Those descriptors are useful to help narrow the differential diagnosis and ensure concordance with a pathologic diagnosis and its accompanying grade assignment of soft-tissue sarcomas. These include a lesion's borders and shape, signal characteristics, and contrast enhancement pattern; the presence of peritumoral edema and peritumoral enhancement; and the presence of lymph nodes. The items most helpful in assisting surgical planning include a lesion's anatomic location, site of origin, size, location relative to a landmark, relationship to adjacent structures, and vascularity including feeding and draining vessels. The authors provide some background information on soft-tissue sarcomas, including their diagnosis and treatment, for the general radiologist and as a refresher for radiologists who are more experienced in tumor imaging. ©RSNA, 2024 See the invited commentary by Murphey in this issue.

Relationships between diagnostic imaging of first carpometacarpal osteoarthritis and pain, functional status, and disease progression: A systematic review

OBJECTIVE

To systematically review the association of pain, function, and progression in first carpometacarpal (CMC) osteoarthritis (OA) with imaging biomarkers and radiography-based staging.

DESIGN

Database searches in PubMed, Embase, and the Cochrane Library, along with citation searching were conducted in accordance with published guidance. Data on the association of imaging with pain, functional status, and disease progression were extracted and synthesized, along with key information on study methodology such as sample sizes, use of control subjects, study design, number of image raters, and blinding. Methodological quality was assessed using National Heart, Lung, and Blood Institute tools.

RESULTS

After duplicate removal, a total of 1969 records were screened. Forty-six articles are included in this review, covering a total of 28,202 study participants, 7263 with first CMC OA. Osteophytes were found to be one of the strongest biomarkers for pain across imaging modalities. Radiographic findings alone showed conflicting relationships with pain. However, Kellgren-Lawrence staging showed consistent associations with pain in various studies. Radiographic, sonographic, and MRI findings and staging showed little association to tools evaluating functional status across imaging modalities. The same imaging methods showed limited ability to predict progression of first CMC OA. A major limitation was the heterogeneity in the study base, limiting synthesis of results.

CONCLUSION

Imaging findings and radiography-based staging systems generally showed strong associations with pain, but not with functional status or disease progression. More research and improved imaging techniques are needed to help physicians better manage patients with first CMC OA.

Automated abdominal CT contrast phase detection using an interpretable and open-source artificial intelligence algorithm

OBJECTIVES

To develop and validate an open-source artificial intelligence (AI) algorithm to accurately detect contrast phases in abdominal CT scans.

MATERIALS AND METHODS

Retrospective study aimed to develop an AI algorithm trained on 739 abdominal CT exams from 2016 to 2021, from 200 unique patients, covering 1545 axial series. We performed segmentation of five key anatomic structures-aorta, portal vein, inferior vena cava, renal parenchyma, and renal pelvis-using TotalSegmentator, a deep learning-based tool for multi-organ segmentation, and a rule-based approach to extract the renal pelvis. Radiomics features were extracted from the anatomical structures for use in a gradient-boosting classifier to identify four contrast phases: non-contrast, arterial, venous, and delayed. Internal and external validation was performed using the F1 score and other classification metrics, on the external dataset "VinDr-Multiphase CT".

RESULTS

The training dataset consisted of 172 patients (mean age, 70 years ± 8, 22% women), and the internal test set included 28 patients (mean age, 68 years ± 8, 14% women). In internal validation, the classifier achieved an accuracy of 92.3%, with an average F1 score of 90.7%. During external validation, the algorithm maintained an accuracy of 90.1%, with an average F1 score of 82.6%. Shapley feature attribution analysis indicated that renal and vascular radiodensity values were the most important for phase classification.

CONCLUSION

An open-source and interpretable AI algorithm accurately detects contrast phases in abdominal CT scans, with high accuracy and F1 scores in internal and external validation, confirming its generalization capability.

CLINICAL RELEVANCE STATEMENT

Contrast phase detection in abdominal CT scans is a critical step for downstream AI applications, deploying algorithms in the clinical setting, and for quantifying imaging biomarkers, ultimately allowing for better diagnostics and increased access to diagnostic imaging.

KEY POINTS

Digital Imaging and Communications in Medicine labels are inaccurate for determining the abdominal CT scan phase. AI provides great help in accurately discriminating the contrast phase. Accurate contrast phase determination aids downstream AI applications and biomarker quantification.

Abdominal CT metrics in 17,646 patients reveal associations between myopenia, myosteatosis, and medical phenotypes: a phenome-wide association study

BACKGROUND

Deep learning facilitates large-scale automated imaging evaluation of body composition. However, associations of body composition biomarkers with medical phenotypes have been underexplored. Phenome-wide association study (PheWAS) techniques search for medical phenotypes associated with biomarkers. A PheWAS integrating large-scale analysis of imaging biomarkers and electronic health record (EHR) data could discover previously unreported associations and validate expected associations. Here we use PheWAS methodology to determine the association of abdominal CT-based skeletal muscle metrics with medical phenotypes in a large North American cohort.

METHODS

An automated deep learning pipeline was used to measure skeletal muscle index (SMI; biomarker of myopenia) and skeletal muscle density (SMD; biomarker of myosteatosis) from abdominal CT scans of adults between 2012 and 2018. A PheWAS was performed with logistic regression using patient sex and age as covariates to assess for associations between CT-derived muscle metrics and 611 common EHR-derived medical phenotypes. PheWAS P values were considered significant at a Bonferroni corrected threshold (α = 0.05/1222).

FINDINGS

17,646 adults (mean age, 56 years ± 19 [SD]; 57.5% women) were included. CT-derived SMI was significantly associated with 268 medical phenotypes; SMD with 340 medical phenotypes. Previously unreported associations with the highest magnitude of significance included higher SMI with decreased cardiac dysrhythmias (OR [95% CI], 0.59 [0.55-0.64]; P < 0.0001), decreased epilepsy (OR, 0.59 [0.50-0.70]; P < 0.0001), and increased elevated prostate-specific antigen (OR, 1.84 [1.47-2.31]; P < 0.0001), and higher SMD with decreased decubitus ulcers (OR, 0.36 [0.31-0.42]; P < 0.0001), sleep disorders (OR, 0.39 [0.32-0.47]; P < 0.0001), and osteomyelitis (OR, 0.43 [0.36-0.52]; P < 0.0001).

INTERPRETATION

PheWAS methodology reveals previously unreported associations between CT-derived biomarkers of myopenia and myosteatosis and EHR medical phenotypes. The high-throughput PheWAS technique applied on a population scale can generate research hypotheses related to myopenia and myosteatosis and can be adapted to research possible associations of other imaging biomarkers with hundreds of EHR medical phenotypes.

FUNDING

National Institutes of Health, Stanford AIMI-HAI pilot grant, Stanford Precision Health and Integrated Diagnostics, Stanford Cardiovascular Institute, Stanford Center for Digital Health, and Stanford Knight-Hennessy Scholars.

Chronic Nonspinal Osteomyelitis in Adults: Consensus Recommendations on Percutaneous Bone Biopsies from the Society of Academic Bone Radiologists

The diagnosis and management of chronic nonspinal osteomyelitis can be challenging, and guidelines regarding the appropriateness of performing percutaneous image-guided biopsies to acquire bone samples for microbiological analysis remain limited. An expert panel convened by the Society of Academic Bone Radiologists developed and endorsed consensus statements on the various indications for percutaneous image-guided biopsies to standardize care and eliminate inconsistencies across institutions. The issued statements pertain to several commonly encountered clinical presentations of chronic osteomyelitis and were supported by a literature review. For most patients, MRI can help guide management and effectively rule out osteomyelitis when performed soon after presentation. Additionally, in the appropriate clinical setting, open wounds such as sinus tracts and ulcers, as well as joint fluid aspirates, can be used for microbiological culture to determine the causative microorganism. If MRI findings are positive, surgery is not needed, and alternative sites for microbiological culture are not available, then percutaneous image-guided biopsies can be performed. The expert panel recommends that antibiotics be avoided or discontinued for an optimal period of 2 weeks prior to a biopsy whenever possible. Patients with extensive necrotic decubitus ulcers or other surgical emergencies should not undergo percutaneous image-guided biopsies but rather should be admitted for surgical debridement and intraoperative cultures. Multidisciplinary discussion and approach are crucial to ensure optimal diagnosis and care of patients diagnosed with chronic osteomyelitis.

Body composition measurements and clinical outcomes in patients with resectable pancreatic adenocarcinoma - analysis from SWOG S1505

BACKGROUND

Sarcopenic obesity and muscle attenuation have been associated with survival in patients with borderline resectable and advanced pancreatic ductal adenocarcinoma (PDA); however, these relationships are unknown for patients with resectable PDA. This study examined the associations between skeletal muscle and adipose tissue as measured on baseline computed tomography (CT) and the overall survival (OS) of participants with resectable PDA in a secondary analysis of the Southwest Oncology Group S1505 clinical trial (identifier: NCT02562716).

METHODS

The S1505 phase II clinical trial enrolled patients with resectable PDA who were randomized to receive modified FOLFIRINOX or gemcitabine and nab-paclitaxel as perioperative chemotherapy, followed by surgical resection. Baseline axial CT images at the L3 level were analyzed with externally validated software, and measurements were recorded for skeletal muscle area and skeletal muscle density, visceral adipose tissue area (VATA) and density, and subcutaneous adipose tissue area and density. The relationships between CT metrics and OS were analyzed using Cox regression models, with adjustment for baseline participant characteristics.

RESULTS

Of 98 eligible participants with available baseline abdominal CT, 8 were excluded because of imaging quality (eg, orthopedic hardware), resulting in 90 evaluable cases: 51 men (57.0%; mean age, 63.2 years [SD, 8.5]; mean body mass index [BMI], 29.3 kg/m2 [SD, 6.4]), 80 White (89.0%), 6 Black (7.0%), and 4 unknown race (4.0%). Sarcopenia was present in 32 participants (35.9%), and sarcopenic obesity was present in 10 participants (11.2%). Univariable analyses for the 6 variables of interest indicated that the standardized mean difference (hazard ratio [HR], 0.75; 95% CI, 0.57-0.98; P = .04) was statistically significantly associated with OS. In models adjusted for sex, race, age, BMI, performance score, contrast use, sarcopenia, and sarcopenic obesity, VATA was statistically significantly associated with OS (HR, 1.58; 95% CI, 1.00-2.51; P = .05). No difference was observed in OS between participants according to sarcopenic obesity or sarcopenia categories. The median OS estimates were 25.1 months for participants without sarcopenic obesity, 18.6 months for participants with sarcopenic obesity, 23.6 months for participants without sarcopenia, and 27.9 months for participants with sarcopenia.

CONCLUSION

This was the first study to systematically evaluate body composition parameters in a prospective multicenter trial of patients with resectable PDA who received perioperative chemotherapy. Visceral adipose tissue was associated with survival; however, there was no association between OS and sarcopenia or sarcopenic obesity. Further studies should evaluate these findings in more detail.

Clinical, functional, and opportunistic CT metrics of sarcopenia at the point of imaging care: analysis of all-cause mortality

PURPOSE

This study examines clinical, functional, and CT metrics of sarcopenia and all-cause mortality in older adults undergoing outpatient imaging.

METHODS

The study included outpatients ≥ 65 years of age undergoing CT or PET/CT at a tertiary care institution. Assessments included screening questionnaires for sarcopenia (SARC-F) and frailty (FRAIL scale), and measurements of grip strength and usual gait speed (6 m course). Skeletal muscle area (SMA), index (SMI, area/height2) and density (SMD) were measured on CT at T12 and L3. A modified SMI was also examined (SMI-m, area/height). Mortality risk was studied with Cox proportional hazard analysis.

RESULTS

The study included 416 patients; mean age 73.8 years [sd 6.2]; mean follow-up 2.9 years (sd 1.34). Abnormal grip, SARC-F, and FRAIL scale assessments were associated with higher mortality risk (HR [95%CI] = 2.0 [1.4-2.9], 1.6 [1.1-2.3], 2.0 [1.4-2.8]). Adjusting for age, higher L3-SMA, T12-SMA, T12-SMI and T12-SMI-m were associated with lower mortality risk (HR [95%CI] = 0.80 [0.65-0.90], 0.76 [0.64-0.90], 0.84 [0.70-1.00], and 0.80 [0.67-0.90], respectively). T12-SMD and L3-SMD were not predictive of mortality. After adjusting for abnormal grip strength and FRAIL scale assessments, T12-SMA and T12-SMI-m remained predictive of mortality risk (HR [95%CI] = 0.83 [0.70-1.00] and 0.80 [0.67-0.97], respectively).

CONCLUSION

CT areal metrics were weaker predictors of all-cause mortality than clinical and functional metrics of sarcopenia in our older patient cohort; a CT density metric (SMD) was not predictive. Of areal CT metrics, SMI (area/height2) appeared to be less effective than non-normalized SMA or SMA normalized by height1.

MRI of patellar stabilizers: Anatomic visibility, inter-reader reliability, and intra-reader reproducibility of primary and secondary ligament anatomy

OBJECTIVE

To compare MRI features of medial and lateral patellar stabilizers in patients with and without patellar instability.

METHODS

Retrospective study of 196 patients (mean age, 33.1 ± 18.5 years; 119 women) after diagnosis of patellar instability (cohort-1, acute patellar dislocation; cohort-2, chronic patellar maltracking) or no patellar instability (cohort-3, acute ACL rupture; cohort-4, chronic medial meniscus tear). On MRI, four medial and four lateral stabilizers were evaluated for visibility and injury by three readers independently. Inter- and intra-reader agreement was determined.

RESULTS

Medial and lateral patellofemoral ligaments (MPFL and LPFL) were mostly or fully visualized in all cases (100%). Of the secondary patellar stabilizers, the medial patellotibial ligament was mostly or fully visualized in 166 cases (84.7%). Other secondary stabilizers were mostly or fully visualized in only a minority of cases (range, 0.5-32.1%). Injury scores for all four medial stabilizers were higher in patients with acute patellar dislocation than the other 3 cohorts (p < .05). Visibility inter- and intra-reader agreement was good for medial stabilizers (κ 0.61-0.78) and moderate-to-good for lateral stabilizers (κ 0.40-0.72). Injury inter- and intra-reader agreement was moderate-to-excellent for medial stabilizers (κ 0.43-0.90) and poor-to-moderate for lateral stabilizers (κ 0-0.50).

CONCLUSION

The MPFL and LPFL were well visualized on MRI while the secondary stabilizers were less frequently visualized. The secondary stabilizers were more frequently visualized medially than laterally, and patellotibial ligaments were more frequently visualized compared to the other secondary stabilizers. Injury to the medial stabilizers was more common with acute patellar dislocation than with chronic patellar maltracking or other knee injuries.

Biomarkers of Body Composition

The importance and impact of imaging biomarkers has been increasing over the past few decades. We review the relevant clinical and imaging terminology needed to understand the clinical and research applications of body composition. Imaging biomarkers of bone, muscle, and fat tissues obtained with dual-energy X-ray absorptiometry, computed tomography, magnetic resonance imaging, and ultrasonography are described.

Association of CT-Derived Skeletal Muscle and Adipose Tissue Metrics with Frailty in Older Adults

RATIONALE AND OBJECTIVES

Tools are needed for frailty screening of older adults. Opportunistic analysis of body composition could play a role. We aim to determine whether computed tomography (CT)-derived measurements of muscle and adipose tissue are associated with frailty.

MATERIALS AND METHODS

Outpatients aged ≥ 55 years consecutively imaged with contrast-enhanced abdominopelvic CT over a 3-month interval were included. Frailty was determined from the electronic health record using a previously validated electronic frailty index (eFI). CT images at the level of the L3 vertebra were automatically segmented to derive muscle metrics (skeletal muscle area [SMA], skeletal muscle density [SMD], intermuscular adipose tissue [IMAT]) and adipose tissue metrics (visceral adipose tissue [VAT], subcutaneous adipose tissue [SAT]). Distributions of demographic and CT-derived variables were compared between sexes. Sex-specific associations of muscle and adipose tissue metrics with eFI were characterized by linear regressions adjusted for age, race, ethnicity, duration between imaging and eFI measurements, and imaging parameters.

RESULTS

The cohort comprised 886 patients (449 women, 437 men, mean age 67.9 years), of whom 382 (43%) met the criteria for pre-frailty (ie, 0.10 < eFI ≤ 0.21) and 138 (16%) for frailty (eFI > 0.21). In men, 1 standard deviation changes in SMD (β = -0.01, 95% confidence interval [CI], -0.02 to -0.001, P = .02) and VAT area (β = 0.008, 95% CI, 0.0005-0.02, P = .04), but not SMA, IMAT, or SAT, were associated with higher frailty. In women, none of the CT-derived muscle or adipose tissue metrics were associated with frailty.

CONCLUSION

We observed a positive association between frailty and CT-derived biomarkers of myosteatosis and visceral adiposity in a sex-dependent manner.

Skeletal Muscle Area on CT: Determination of an Optimal Height Scaling Power and Testing for Mortality Risk Prediction

BACKGROUND. Sarcopenia is commonly assessed on CT by use of the skeletal muscle index (SMI), which is calculated as the skeletal muscle area (SMA) at L3 divided by patient height squared (i.e., a height scaling power of 2). OBJECTIVE. The purpose of this study was to determine the optimal height scaling power for SMA measurements on CT and to test the influence of the derived optimal scaling power on the utility of SMI in predicting all-cause mortality. METHODS. This retrospective study included 16,575 patients (6985 men, 9590 women; mean age, 56.4 years) who underwent abdominal CT from December 2012 through October 2018. The SMA at L3 was determined using automated software. The sample was stratified into two groups: 5459 patients without major medical conditions (based on ICD-9 and ICD-10 codes) who were included in the analysis for determining the optimal height scaling power and 11,116 patients with major medical conditions who were included for the purpose of testing this power. The optimal scaling power was determined by allometric analysis (whereby regression coefficients were fitted to log-linear sex-specific models relating height to SMA) and by analysis of statistical independence of SMI from height across scaling powers. Cox proportional hazards models were used to test the influence of the derived optimal scaling power on the utility of SMI in predicting all-cause mortality. RESULTS. In allometric analysis, the regression coefficient of log(height) in patients 40 years old and younger was 1.02 in men and 1.08 in women, and in patients older than 40 years old, it was 1.07 in men and 1.10 in women (all p < .05 vs regression coefficient of 2). In analyses for statistical independence of SMI from height, the optimal height scaling power (i.e., those yielding correlations closest to 0) was, in patients 40 years old and younger, 0.97 in men and 1.08 in women, whereas in patients older than 40 years old, it was 1.03 in men and 1.09 in women. In the Cox model used for testing, SMI predicted all-cause mortality with a higher concordance index using of a height scaling power of 1 rather than 2 in men (0.675 vs 0.663, p < .001) and in women (0.664 vs 0.653, p < .001). CONCLUSION. The findings support a height scaling power of 1, rather than a conventional power of 2, for SMI computation. CLINICAL IMPACT. A revised height scaling power for SMI could impact the utility of CT-based sarcopenia diagnoses in risk assessment.

Advanced Arthritis of the Carpus: Preoperative Planning Practices of 337 Hand Surgeons

Background  Surgical procedure selection for carpal arthritis depends on which articular surfaces are affected, but there is no consensus on how to preoperatively evaluate cartilage surfaces. Despite advances in cross-sectional imaging, the utility of advanced imaging for preoperative decision-making has not been well established. Objectives  Our objective was to assess if there is an added value to presurgical advanced imaging or diagnostic procedures in planning for carpal arthrodesis or carpectomy and to determine what imaging or diagnostic procedures influence surgical treatment options. Methods  A seven-question survey was sent to 2,400 hand surgeons. Questions assessed which articular surfaces surgeons consider important for decision-making, which imaging modalities surgeons employ, and how often surgeons utilize diagnostic arthroscopy before performing carpectomy or arthrodesis procedures. Results  A total of 337 (14%) surveys were analyzed. The capitolunate articulation (alone or in combination) was most frequently reported to impact surgical decision-making (48.1%). Most surgeons (86.6%) reported that standard plain radiographs are usually sufficient. Few surgeons reported always obtaining magnetic resonance imaging (MRI) or computed tomography (CT), with 44.2% of surgeons believing that MRI is never useful and 38.4% believing that CT is never useful. Most surgeons (68.2%) reported that they never perform wrist arthroscopy as part of their decision-making process. Conclusions  This study provides information on the decision-making process in the surgical management of carpal arthritis. Given advances in cross-sectional imaging, further studies are needed to determine the utility of MRI and CT for the planning of surgical procedures in the treatment of arthritis of the carpus. Level of Evidence  Level 4.

Opportunistic assessment of ischemic heart disease risk using abdominopelvic computed tomography and medical record data: a multimodal explainable artificial intelligence approach

Current risk scores using clinical risk factors for predicting ischemic heart disease (IHD) events-the leading cause of global mortality-have known limitations and may be improved by imaging biomarkers. While body composition (BC) imaging biomarkers derived from abdominopelvic computed tomography (CT) correlate with IHD risk, they are impractical to measure manually. Here, in a retrospective cohort of 8139 contrast-enhanced abdominopelvic CT examinations undergoing up to 5 years of follow-up, we developed multimodal opportunistic risk assessment models for IHD by automatically extracting BC features from abdominal CT images and integrating these with features from each patient's electronic medical record (EMR). Our predictive methods match and, in some cases, outperform clinical risk scores currently used in IHD risk assessment. We provide clinical interpretability of our model using a new method of determining tissue-level contributions from CT along with weightings of EMR features contributing to IHD risk. We conclude that such a multimodal approach, which automatically integrates BC biomarkers and EMR data, can enhance IHD risk assessment and aid primary prevention efforts for IHD. To further promote research, we release the Opportunistic L3 Ischemic heart disease (OL3I) dataset, the first public multimodal dataset for opportunistic CT prediction of IHD.

Real-time MRI of the moving wrist at 0.55 tesla

OBJECTIVES

Magnetic resonance imaging (MRI) using 1.5T or 3.0T systems is routinely employed for assessing wrist pathology; however, due to off-resonance artifacts and high power deposition, these high-field systems have drawbacks for real-time (RT) imaging of the moving wrist. Recently, high-performance 0.55T MRI systems have become available. In this proof-of-concept study, we tested the hypothesis that RT-MRI during continuous, active, and uninterrupted wrist motion is feasible with a high-performance 0.55T system at temporal resolutions below 100 ms and that the resulting images provide visualization of tissues commonly interrogated for assessing dynamic wrist instability.

METHODS

Participants were scanned during uninterrupted wrist radial-ulnar deviation and clenched fist maneuvers. Resulting images (nominal temporal resolution of 12.7-164.6 ms per image) were assessed for image quality. Feasibility of static MRI to supplement RT-MRI acquisition was also tested.

RESULTS

The RT images with temporal resolutions < 100 ms demonstrated low distortion and image artifacts, and higher reader assessment scores. Static MRI scans showed the ability to assess anatomical structures of interest in the wrist.

CONCLUSION

RT-MRI of the wrist at a high temporal resolution, coupled with static MRI, is feasible with a high-performance 0.55T system, and may enable improved assessment of wrist dynamic dysfunction and instability.

ADVANCES IN KNOWLEDGE

Real-time MRI of the moving wrist is feasible with high-performance 0.55T and may improve the evaluation of dynamic dysfunction of the wrist.

Muscle Steatosis and Fibrosis in Older Adults, From the AJR Special Series on Imaging of Fibrosis

The purpose of this article is to review steatosis and fibrosis of skeletal muscle, focusing on older adults. Although CT, MRI, and ultrasound are commonly used to image skeletal muscle and provide diagnoses for a variety of medical conditions, quantitative assessment of muscle steatosis and fibrosis is uncommon. This review provides radiologists with a broad perspective on muscle steatosis and fibrosis in older adults by considering their public health impact, biologic mechanisms, and evaluation using CT, MRI, and ultrasound. Promising directions in clinical research that employ artificial intelligence algorithms and the imaging assessment of biologic age are also reviewed. The presented imaging methods hold promise for improving the evaluation of common conditions affecting older adults including sarcopenia, frailty, and cachexia.

Knee MRI: Meniscus Roots, Ramps, Repairs, and Repercussions

Menisci play an essential role in maintaining normal pain-free function of the knee. While there are decades of MRI literature on the tears involving the meniscus body and horns, there is now a surge in knowledge regarding injuries at the meniscus roots and periphery. The authors briefly highlight new insights into meniscus anatomy and then summarize recent developments in the understanding of meniscus injuries that matter, emphasizing meniscus injuries at the root and peripheral (eg, ramp) regions that may be missed easily at MRI and arthroscopy. Root and ramp tears are important to diagnose because they may be amenable to repair. However, if these tears are left untreated, ongoing pain and accelerated cartilage degeneration may ensue. The posterior roots of the medial and lateral menisci are most commonly affected by injury, and each of these injuries is associated with distinctive clinical profiles, MRI findings, and tear patterns. Specific diagnostic pitfalls can make the roots challenging to evaluate, including MRI artifacts and anatomic variations. As with root tears, MRI interpretation and orthopedic treatment have important differences for injuries at the medial versus lateral meniscus (LM) periphery (located at or near the meniscocapsular junction). Medially, ramp lesions typically occur in the setting of an anterior cruciate ligament rupture and are generally classified into five patterns. Laterally, the meniscocapsular junction may be injured in association with tibial plateau fractures, but disruption of the popliteomeniscal fascicles may also result in a hypermobile LM. Updated knowledge of the meniscus root and ramp tears is crucial in optimizing diagnostic imaging before repair and understanding the clinical repercussions. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available in the Online Learning Center.

Ultrasound Identifies First Rib Stress Fractures: A Case Series in National Collegiate Athletic Association Division I Athletes

Isolated first rib stress fractures in athletes are thought to be rare. In this case series, 3 National Collegiate Athletic Association Division I athletes developed isolated first rib stress fractures over the span of 1 year, indicating that these injuries may occur more often than previously understood. These fractures can be easily missed because of the low incidence, lack of clinical suspicion, and vague presentation. Further, radiographs can fail to reveal such fractures. To our knowledge, this is the largest case series of athletes with first rib stress fractures presenting with vague rhomboid interscapular pain. We also demonstrated that ultrasound successfully visualized these injuries; in the hands of an ultrasonographer or clinical provider trained in musculoskeletal ultrasound, this technique offers an advantageous point-of-care screening imaging modality.

Fast volumetric ultrasound facilitates high-resolution 3D mapping of tissue compartments

Volumetric ultrasound imaging has the potential for operator-independent acquisition and enhanced field of view. Panoramic acquisition has many applications across ultrasound; spanning musculoskeletal, liver, breast, and pediatric imaging; and image-guided therapy. Challenges in high-resolution human imaging, such as subtle motion and the presence of bone or gas, have limited such acquisition. These issues can be addressed with a large transducer aperture and fast acquisition and processing. Programmable, ultrafast ultrasound scanners with a high channel count provide an unprecedented opportunity to optimize volumetric acquisition. In this work, we implement nonlinear processing and develop distributed beamformation to achieve fast acquisition over a 47-centimeter aperture. As a result, we achieve a 50-micrometer -6-decibel point spread function at 5 megahertz and resolve in-plane targets. A large volume scan of a human limb is completed in a few seconds, and in a 2-millimeter dorsal vein, the image intensity difference between the vessel center and surrounding tissue was ~50 decibels, facilitating three-dimensional reconstruction of the vasculature.

Patellar Tracking: An Old Problem with New Insights

Patellofemoral pain and instability are common indications for imaging that are encountered in everyday practice. The authors comprehensively review key aspects of patellofemoral instability pertinent to radiologists that can be seen before the onset of osteoarthritis, highlighting the anatomy, clinical evaluation, diagnostic imaging, and treatment. Regarding the anatomy, the medial patellofemoral ligament (MPFL) is the primary static soft-tissue restraint to lateral patellar displacement and is commonly reconstructed surgically in patients with MPFL dysfunction and patellar instability. Osteoarticular abnormalities that predispose individuals to patellar instability include patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Clinically, patients with patellar instability may be divided into two broad groups with imaging findings that sometimes overlap: patients with a history of overt patellar instability after a traumatic event (eg, dislocation, subluxation) and patients without such a history. In terms of imaging, radiography is generally the initial examination of choice, and MRI is the most common cross-sectional examination performed preoperatively. For all imaging techniques, there has been a proliferation of published radiologic measurement methods. The authors summarize the most common validated measurements for patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Given that static imaging is inherently limited in the evaluation of patellar motion, dynamic imaging with US, CT, or MRI may be requested by some surgeons. The primary treatment strategy for patellofemoral pain is conservative. Surgical treatment options include MPFL reconstruction with or without osseous corrections such as trochleoplasty and tibial tubercle osteotomy. Postoperative complications evaluated at imaging include patellar fracture, graft failure, graft malposition, and medial patellar subluxation. ^©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Generalizability of Deep Learning Segmentation Algorithms for Automated Assessment of Cartilage Morphology and MRI Relaxometry

BACKGROUND

Deep learning (DL)-based automatic segmentation models can expedite manual segmentation yet require resource-intensive fine-tuning before deployment on new datasets. The generalizability of DL methods to new datasets without fine-tuning is not well characterized.

PURPOSE

Evaluate the generalizability of DL-based models by deploying pretrained models on independent datasets varying by MR scanner, acquisition parameters, and subject population.

STUDY TYPE

Retrospective based on prospectively acquired data.

POPULATION

Overall test dataset: 59 subjects (26 females); Study 1: 5 healthy subjects (zero females), Study 2: 8 healthy subjects (eight females), Study 3: 10 subjects with osteoarthritis (eight females), Study 4: 36 subjects with various knee pathology (10 females).

FIELD STRENGTH/SEQUENCE

A 3-T, quantitative double-echo steady state (qDESS).

ASSESSMENT

Four annotators manually segmented knee cartilage. Each reader segmented one of four qDESS datasets in the test dataset. Two DL models, one trained on qDESS data and another on Osteoarthritis Initiative (OAI)-DESS data, were assessed. Manual and automatic segmentations were compared by quantifying variations in segmentation accuracy, volume, and T2 relaxation times for superficial and deep cartilage.

STATISTICAL TESTS

Dice similarity coefficient (DSC) for segmentation accuracy. Lin's concordance correlation coefficient (CCC), Wilcoxon rank-sum tests, root-mean-squared error-coefficient-of-variation to quantify manual vs. automatic T2 and volume variations. Bland-Altman plots for manual vs. automatic T2 agreement. A P value < 0.05 was considered statistically significant.

RESULTS

DSCs for the qDESS-trained model, 0.79-0.93, were higher than those for the OAI-DESS-trained model, 0.59-0.79. T2 and volume CCCs for the qDESS-trained model, 0.75-0.98 and 0.47-0.95, were higher than respective CCCs for the OAI-DESS-trained model, 0.35-0.90 and 0.13-0.84. Bland-Altman 95% limits of agreement for superficial and deep cartilage T2 were lower for the qDESS-trained model, ±2.4 msec and ±4.0 msec, than the OAI-DESS-trained model, ±4.4 msec and ±5.2 msec.

DATA CONCLUSION

The qDESS-trained model may generalize well to independent qDESS datasets regardless of MR scanner, acquisition parameters, and subject population.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Ageism in Society and Its Health Impact

Ageism is an increasingly recognized form of cognitive bias involving stereotypes, prejudice, and discrimination directed toward people on the basis of their age. Age-based bias influences how medicine is practiced and can result in profoundly negative but avoidable health outcomes. Awareness and education regarding ageism and its manifestations can improve the ability to identify and mitigate ageism. As this Viewpoint describes, radiologists are well situated to be part of the solution in addressing ageism.

Editorial Comment: Death and Taxes…and Artificial Intelligence

This Editorial Comment discusses the following AJR article: Technical Adequacy of Fully Automated Artificial Intelligence Body Composition Tools: Assessment in a Heterogeneous Sample of External CT Examinations.

Pre-operative imaging for surgical decision-making and the frequency of wrist arthrodesis and carpectomy procedures: a scoping review

OBJECTIVES

Our objectives were to (1) analyze the imaging modalities utilized pre-operatively that influence surgical decision-making for wrist arthrodesis and carpectomy procedures and (2) determine the type and frequency of these procedures for the treatment of wrist arthritis.

MATERIALS AND METHODS

This review was performed according to the guidelines of PRISMA Extension for Scoping Reviews. Using PubMed, Embase, and Scopus, peer-reviewed literature from 2011 to 2022 was searched for use of imaging in pre-operative decision-making for wrist arthrodesis and carpectomy surgical procedures. Data were compiled to determine the type(s) of imaging modalities used pre-operatively and types of surgical techniques reported in the literature.

RESULTS

Of 307 articles identified, 35 articles satisfied eligibility criteria, with a total of 1377 patients (68% men; age mean, 50.9 years [range, 10-81]) and 1428 wrist surgical interventions. Radiography was reported for pre-operative planning in all articles for all patients. Pre-operative cross-sectional imaging was reported in 2 articles (5.7%), but no articles reported detailed data on how CT or MRI influenced pre-operative wrist arthrodesis and carpectomy procedure decision-making. A dozen different types of surgical techniques were reported. The four most common procedures were four-corner arthrodesis with scaphoid excision (846, 59%), proximal row carpectomy (239, 17%), total wrist arthrodesis (130, 9%), and scaphocapitate arthrodesis (53, 4%).

CONCLUSION

Radiography is always used in pre-operative decision-making, but the literature lacks data on the influence of CT and MRI for selecting among a dozen different types of wrist arthrodesis and carpectomy procedures.

Imaging of Sarcopenia

Sarcopenia is currently underdiagnosed and undertreated, but this is expected to change because sarcopenia is now recognized with a specific diagnosis code that can be used for billing in some countries, as well as an expanding body of research on prevention, diagnosis, and management. This article focuses on practical issues of increasing interest by highlighting 3 hot topics fundamental to understanding sarcopenia in older adults: definitions and terminology, current diagnostic imaging techniques, and the emerging role of opportunistic computed tomography.

Sarcopenia in rheumatic disorders: what the radiologist and rheumatologist should know

Sarcopenia is defined as the loss of muscle mass, strength, and function. Increasing evidence shows that sarcopenia is common in patients with rheumatic disorders. Although sarcopenia can be diagnosed using bioelectrical impedance analysis or DXA, increasingly it is diagnosed using CT, MRI, and ultrasound. In rheumatic patients, CT and MRI allow "opportunistic" measurement of body composition, including surrogate markers of sarcopenia, from studies obtained during routine patient care. Recognition of sarcopenia is important in rheumatic patients because sarcopenia can be associated with disease progression and poor outcomes. This article reviews how opportunistic evaluation of sarcopenia in rheumatic patients can be accomplished and potentially contribute to improved patient care.

Rapidly progressive idiopathic arthritis of the hip: incidence and risk factors in a controlled cohort study of 1471 patients after intra-articular corticosteroid injection

OBJECTIVE

Rapidly progressive idiopathic arthritis of the hip (RPIA) is defined by progressive joint space narrowing of > 2 mm or > 50% within 1 year. Our aims were to assess (a) the occurrence of RPIA after intra-articular steroid injection, and (b) possible risk factors for RPIA including: patient age, BMI, joint space narrowing, anesthetic and steroid selections, bone mineral density, and pain reduction after injection.

MATERIALS AND METHODS

A retrospective search of our imaging database identified 1471 patients who had undergone fluoroscopically guided hip injection of triamcinolone acetonide (Kenalog) and anesthetic within a 10-year period. Patient data, including hip DXA results and patient-reported pain scores, were recorded. Pre-injection and follow-up radiographs were assessed for joint space narrowing, femoral head deformity, and markers of osteoarthritis. Osteoarthritis was graded by Croft score. Associations between patient characteristics and outcome variables were analyzed.

RESULTS

One hundred six of 1471 injected subjects (7.2%) met the criteria for RPIA. A control group of 161 subjects was randomly selected from subjects who underwent hip injections without developing RPIA. Compared to controls, patients with RPIA were older, had narrower hip joint spaces, and higher Croft scores before injection (p < 0.05). Patients who developed RPIA did not differ from controls in sex, BMI, hip DXA T-score, anesthetic and steroid injectates, or pain improvement after injection.

CONCLUSION

We found that approximately 7% of patients undergoing steroid hip injection developed RPIA. More advanced patient age, greater joint space narrowing, and more severe osteoarthritis are risk factors for the development of RPIA after intra-articular steroid injection.

Assessment of Myofascial Trigger Points via Imaging: A Systematic Review

ABSTRACT

This study systematically reviewed the published literature on the objective characterization of myofascial pain syndrome and myofascial trigger points using imaging methods. PubMed, Embase, Ovid, and the Cochrane Library databases were used, whereas citation searching was conducted in Scopus. Citations were restricted to those published in English and in peer-reviewed journals between 2000 and 2021. Of 1762 abstracts screened, 69 articles underwent full-text review, and 33 were included. Imaging data assessing myofascial trigger points or myofascial pain syndrome were extracted, and important qualitative and quantitative information on general study methodologies, study populations, sample sizes, and myofascial trigger point/myofascial pain syndrome evaluation were tabulated. Methodological quality of eligible studies was assessed based on the Quality Assessment of Diagnostic Accuracy Studies criteria. Biomechanical properties and blood flow of active and latent myofascial trigger points assessed via imaging were found to be quantifiably distinct from those of healthy tissue. Although these studies show promise, more studies are needed. Future studies should focus on assessing diagnostic test accuracy and testing the reproducibility of results to establish the best performing methods. Increasing methodological consistency would further motivate implementing imaging methods in larger clinical studies. Considering the evidence on efficacy, cost, ease of use and time constraints, ultrasound-based methods are currently the imaging modalities of choice for myofascial pain syndrome/myofascial trigger point assessment.

The Biomechanical Effects of Augmentation With Flat Braided Suture on Dorsal Intercarpal Ligament Capsulodesis for Scapholunate Instability

PURPOSE

Selecting treatment for scapholunate (SL) instability is notoriously difficult. Many methods of reconstruction have been described, but no procedure demonstrates clear superiority. New methods proposed use internal bracing (IB) with suture anchors and flat braided suture (FBS), alone or as an augmentation with tendon autograft for SL ligament injuries. Our goal was to use computed tomography (CT) to analyze alignment of the SL joint after 3 different modes of fixation of SL instability: after reconstruction with IB incorporating either tendon autograft or the dorsal intercarpal ligament (DICL), or DICL capsulodesis without FBS.

METHODS

Ten fresh-frozen, matched-pair, forearm-to-hand specimens were used. Serial sectioning of the SL stabilizing ligaments was performed and the SL interval was measured with CT. We reconstructed the SL ligament with DICL capsulodesis alone (DICL) or with IB augmented with either tendon autograft (IB plus T) or DICL (DICL plus IB). The SL interval was measured with CT. Specimens underwent 500 weighted cycles on a jig and were reimaged. Differences in SL interval after repair and cycling were compared.

RESULTS

Dorsal intercarpal ligament capsulodesis augmented with IB best maintained the SL interval before and after cycling. Dorsal intercarpal ligament capsulodesis alone was inferior to DICL plus IB and IB plus T both before and after cycling.

CONCLUSIONS

Dorsal intercarpal ligament capsulodesis augmented with IB appears to maintain better SL joint reduction than IB with tendon autograft.

CLINICAL RELEVANCE

This work serves as a necessary step for further study of the biomechanical strength and clinical application of FBS technology in the reconstruction of SL instability. Flat braided suture augmentation of DICL capsulodesis may provide another option to consider for reconstruction of SL instability.

Feasibility of dual-phase 99mTc-MDP SPECT/CT imaging in rheumatoid arthritis evaluation

Background

To prospectively demonstrate the feasibility of performing dual-phase SPECT/CT for the assessment of the small joints of the hands of rheumatoid arthritis (RA) patients, and to evaluate the reliability of the quantitative and qualitative measures derived from the resulting images.

Methods

A SPECT/CT imaging protocol was developed in this pilot study to scan both hands simultaneously in participants with RA, in two phases of ^99mTc-MDP radiotracer uptake, namely the soft-tissue blood pool phase (within 15 minutes after radiotracer injection) and osseous phase (after 3 hours). Joints were evaluated qualitatively (normal vs. abnormal uptake) and quantitatively [by measuring a newly developed metric, maximum corrected count ratio (MCCR)]. Qualitative and quantitative evaluations were repeated to assess reliability.

Results

Four participants completed seven studies (all four were imaged at baseline, and three of them at follow-up after 1-month of arthritis therapy). A total of 280 joints (20 per hand) were evaluated. The MCCR from soft-tissue phase scans was significantly higher for clinically abnormal joints compared to clinically normal ones; P<0.001, however the MCCR from the osseous phase scans were not different between the two joint groups. Intraclass Correlation Coefficient (ICC) for MCCR was excellent [0.9789, 95% confidence interval (CI): 0.9734-0.9833]. Intra-observer agreement for qualitative SPECT findings was substantial for both the soft-tissue phase (kappa =0.78, 95% CI: 0.72-0.83) and osseous-phase (kappa =0.70, 95% CI: 0.64-0.76) scans.

Conclusions

Extracting reliable quantitative and qualitative measures from dual-phase 99mTc-MDP SPECT/CT hand scans is feasible in RA patients. SPECT/CT may provide a unique means for assessing both synovitis and osseous involvement in RA joints using the same radiotracer injection.

Computed Tomography Measurements of Sarcopenia Predict Length of Stay in Older Burn Patients

Sarcopenia and frailty are associated with aging. In older burn patients, frailty has been associated with mortality and discharge disposition, but sarcopenia has not been examined. This study aims to investigate the relationship between frailty and computed tomography (CT)-derived sarcopenia with length of stay and mortality in older burn patients. Burn patients ≥60 years old admitted between 2008 and 2017 who had chest or abdomen CT scans within 1 week of admission were evaluated. Frailty was assessed using the Canadian Study of Health and Aging Clinical Frailty Scale (CFS). Sarcopenia was assessed on CT exams by measuring skeletal muscle index (SMI) of paraspinal muscles at T12 and all skeletal muscles at L3. The relationship between frailty scores and SMI with length of stay (LOS) and mortality was determined using logistic regression. Eighty-three patients (59 men; mean age 70.2 ± 8.5 years) had chest (n = 50) or abdomen (n = 60) CT scans. Mean TBSA = 14.3 ± 14.0%, LOS = 25.8 ± 21.3 days, CFS = 4.36 ± 0.99. Sixteen patients (19.3%) died while in the hospital. CT-derived measurement of SMI at T12 was significantly associated with LOS (P < .05), but not with mortality (P = .561). CT-derived metrics at L3 were not significantly associated with outcomes. CFS was not associated with LOS (P = .836) or mortality (P = .554). In older burn patients, low SMI of the paraspinal muscles at T12 was associated with longer LOS.

Automated Muscle Measurement on Chest CT Predicts All-Cause Mortality in Older Adults From the National Lung Screening Trial

BACKGROUND

Muscle metrics derived from computed tomography (CT) are associated with adverse health events in older persons, but obtaining these metrics using current methods is not practical for large datasets. We developed a fully automated method for muscle measurement on CT images. This study aimed to determine the relationship between muscle measurements on CT with survival in a large multicenter trial of older adults.

METHOD

The relationship between baseline paraspinous skeletal muscle area (SMA) and skeletal muscle density (SMD) and survival over 6 years was determined in 6,803 men and 4,558 women (baseline age: 60-69 years) in the National Lung Screening Trial (NLST). The automated machine learning pipeline selected appropriate CT series, chose a single image at T12, and segmented left paraspinous muscle, recording cross-sectional area and density. Associations between SMA and SMD with all-cause mortality were determined using sex-stratified Cox proportional hazards models, adjusted for age, race, height, weight, pack-years of smoking, and presence of diabetes, chronic lung disease, cardiovascular disease, and cancer at enrollment.

RESULTS

After a mean 6.44 ± 1.06 years of follow-up, 635 (9.33%) men and 265 (5.81%) women died. In men, higher SMA and SMD were associated with a lower risk of all-cause mortality, in fully adjusted models. A one-unit standard deviation increase was associated with a hazard ratio (HR) = 0.85 (95% confidence interval [CI] = 0.79, 0.91; p < .001) for SMA and HR = 0.91 (95% CI = 0.84, 0.98; p = .012) for SMD. In women, the associations did not reach significance.

CONCLUSION

Higher paraspinous SMA and SMD, automatically derived from CT exams, were associated with better survival in a large multicenter cohort of community-dwelling older men.

Accurate prediction of lumbar microdecompression level with an automated MRI grading system

OBJECTIVE

Lumbar spine MRI interpretations have high variability reducing utility for surgical planning. This study evaluated a convolutional neural network (CNN) framework that generates automated MRI grading for its ability to predict the level that was surgically decompressed.

MATERIALS AND METHODS

Patients who had single-level decompression were retrospectively evaluated. Sagittal T2 images were processed by a CNN (SpineNet), which provided grading for the following: central canal stenosis, disc narrowing, disc degeneration, spondylolisthesis, upper/lower endplate morphologic changes, and upper/lower marrow changes. The grades were used to calculate an aggregate score. The variables and the aggregate score were analyzed for their ability to predict the surgical level. For each surgical level subgroup, the surgical level aggregate scores were compared with the non-surgical levels.

RESULTS

A total of 141 patients met the inclusion criteria (82 women, 59 men; mean age 64 years; age range 28-89 years). SpineNet did not identify central canal stenosis in 32 patients. Of the remaining 109, 96 (88%) patients had a decompression at the level of greatest stenosis. The higher stenotic grade was present only at the surgical level in 82/96 (85%) patients. The level with the highest aggregate score matched the surgical level in 103/141 (73%) patients and was unique to the surgical level in 91/103 (88%) patients. Overall, the highest aggregate score identified the surgical level in 91/141 (65%) patients. The aggregate MRI score mean was significantly higher for the L3-S1 surgical levels.

CONCLUSION

A previously developed CNN framework accurately predicts the level of microdecompression for degenerative spinal stenosis in most patients.

Preoperative MRI of Articular Cartilage in the Knee: A Practical Approach

Articular cartilage of the knee can be evaluated with high accuracy by magnetic resonance imaging (MRI) in preoperative patients with knee pain, but image quality and reporting are variable. This article discusses the normal MRI appearance of articular cartilage as well as the common MRI abnormalities of knee cartilage that may be considered for operative treatment. This article focuses on a practical approach to preoperative MRI of knee articular cartilage using routine MRI techniques. Current and future directions of knee MRI related to articular cartilage are also discussed.

Capsular thinning on magnetic resonance arthrography is associated with intra-operative hip joint laxity in women

Hip microinstability is a recognized cause of hip pain in young patients. Intra-operative evaluation is used to confirm the diagnosis, but limited data exist associating magnetic resonance arthrography (MRA) findings with hip microinstability. To determine if a difference exists in the thickness of the anterior joint capsule and/or the width of the anterior joint recess on MRA in hip arthroscopy patients with and without an intra-operative diagnosis of hip laxity. Sixty-two hip arthroscopy patients were included in the study. Two musculoskeletal radiologists blinded to surgical results reviewed the MRAs for two previously described findings: (i) anterior joint capsule thinning; (ii) widening of the anterior joint recess distal to the zona orbicularis. Operative reports were reviewed for the diagnosis of joint laxity. In all patients with and without intra-operative laxity, there were no significant differences with either MRA measurement. However, twenty-six of 27 patients with intra-operative laxity were women compared with 11 of 35 patients without laxity (P < 0.001). In subgroup analysis of women, the intra-operative laxity group had a higher rate of capsular thinning compared with the non-laxity group (85% versus 45%; P = 0.01). A 82% of women with capsular thinning also had intra-operative laxity, compared with 40% without capsular thinning (P = 0.01). There were no differences regarding the width of the anterior joint recess. In this study, there was an association between capsular thinning and intra-operative laxity in female patients. Measuring anterior capsule thickness on a pre-operative MRA may be useful for the diagnosis of hip microinstability.

Subchondroplasty of the Ankle and Hindfoot for Treatment of Osteochondral Lesions and Stress Fractures: Initial Imaging Experience

Objective:To describe the imaging findings of patients treated with subchondroplasty (SCP) of the ankle and hindfoot. Materials and Methods: Eighteen patients (10 men, 8 women; age mean 43.1 years [range 20.1-67.7 years]) underwent ankle and hindfoot SCP at a single center over a 14-month period. Imaging data were reviewed retrospectively by 2 radiologists by consensus interpretation, including preoperative radiography (18), computed tomography (CT) (11), and magnetic resonance imaging (MRI) (13) and postoperative radiography (10), CT (4), and MRI (6). Follow-up imaging was acquired 1 month to 1.6 years following SCP. Results: Indications for SCP included symptomatic bone marrow lesions (BMLs) secondary to an osteochondral lesion (OCL) (16/18) or stress fracture (2/18). While focal radiodensity related to the SCP procedure was retrospectively identifiable on postoperative radiography in all except 1 case (10/11), postprocedural findings were not described by the interpreting radiologist in 6/11 cases. On CT, the average injected synthetic calcium phosphate (CaP) volume was 1.15 cm³ (SD = 0.33 cm³); mean CT attenuation of the injectate was 1220 HU (range 1058-1465 HU). In all patients who had pre- and postoperative MRI (5/18), BML size decreased on follow-up MRI. Extra-osseous extrusion of CaP was not seen on postoperative radiography, CT, or MRI. Conclusion: Physicians should be aware of the expanding preoperative indications and postoperative imaging findings of SCP, which is being performed with increasing frequency in the ankle and hindfoot.Levels of Evidence: Diagnostic, Level III: Retrospective cohort study.

Association of adipose tissue and skeletal muscle metrics with overall survival and postoperative complications in soft tissue sarcoma patients: an opportunistic study using computed tomography

Background

To determine the relationship between adipose tissue and skeletal muscle measurements on computed tomography (CT) and overall survival and major postoperative complications in patients with soft-tissue sarcoma (STS).

Methods

The retrospective study included 137 STS patients (75 men, 62 women; mean age, 53 years, SD 17.7; mean BMI, 28.5, SD 6.6) who had abdominal CT exams. On a single CT image, at the L4 pedicle level, measurements of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and skeletal muscle area and attenuation were obtained using clinical PACS and specialized segmentation software. Clinical information was recorded, including STS characteristics (size, depth, grade, stage, and site), overall survival, and postoperative complications. The relationships between CT metrics and survival were analyzed using Cox proportional hazard models and those between CT metrics and postoperative complications using logistic regression models.

Results

There were 33 deaths and 41 major postoperative complications. Measured on clinical PACS, the psoas area (P=0.003), psoas index (P=0.006), psoas attenuation (P=0.011), and total muscle attenuation (P=0.023) were associated with overall survival. Using specialized software, psoas attenuation was also associated with overall survival (P=0.018). Adipose tissue metrics were not associated with survival or postoperative complications.

Conclusions

In STS patients, CT-derived muscle size and attenuation are associated with overall survival. These prognostic biomarkers can be obtained using specialized segmentation software or routine clinical PACS.

Opportunistic muscle measurements on staging chest CT for extremity and truncal soft tissue sarcoma are associated with survival

BACKGROUND AND OBJECTIVES

Computed tomography (CT) measurements of sarcopenia have been proposed as biomarkers associated with outcomes in various cancers and have typically been evaluated at the L3 vertebral level. However, staging imaging for patients with extremity and truncal soft tissue sarcoma (STS) often only includes chest CT imaging which precludes evaluation at L3. Therefore, we sought to evaluate muscle metrics at T12 on standard staging chest CT scans and evaluate for correlation with overall and event-free survival in patients with STS.

METHODS

CT chest imaging for 89 patients with intermediate and high-grade STS (53 male, 36 female; 58.5 ± 19.0 years old, follow-up 37.4 ± 27.1 months) was reviewed on PACS at T12 for skeletal muscle density (SMD) and skeletal muscle index (SMI).

RESULTS

Overall survival increased with increased SMD on univariate (hazard ratio [HR] = 0.61 [0.43, 0.86]) and age-adjusted analysis (HR = 0.65 [0.42, 0.89]. Event-free survival also increased with increased SMD in univariate analyses (HR = 0.68 [0.49, 0.95]) but did not maintain significance after adjusting for age (HR = 0.68 [0.43, 1.07]). SMI was not a predictor of overall or event-free survival.

CONCLUSIONS

Higher SMD measured on routinely obtained staging chest CTs in STS patients is associated with improved survival.

Approaches to Assessment of Muscle Mass and Myosteatosis on Computed Tomography: A Systematic Review

BACKGROUND/OBJECTIVE

There is increasing use of computed tomography (CT) in sarcopenia research using a wide variety of techniques. We performed a systematic review of the CT literature to identify the differences between approaches used.

METHODS

A comprehensive search of PubMed from 1983 to 2017 was performed to identify studies that used CT muscle measurements to assess muscle mass and myosteatosis. The CT protocols were evaluated based on anatomic landmark(s), thresholding, muscle(s) segmented, key measurement (ie, muscle attenuation, cross-sectional area, volume), derived variables, and analysis software. From the described search, 657 articles were identified and 388 studies met inclusion criteria for this systematic review.

RESULTS

Muscle mass was more commonly assessed than myosteatosis (330 vs. 125). The most commonly assessed muscle or muscle groups were total abdominal wall musculature (142/330 and 49/125 for muscle mass and myosteatosis, respectively) and total thigh musculature (90/330 and 48/125). The most commonly used landmark in the abdomen was the L3 vertebra (123/142 and 45/49 for muscle mass and myosteatosis, respectively). Skeletal muscle index and intermuscular adipose tissue were the most commonly used measures of abdominal wall muscle mass (114/142) and myosteatosis (27/49), respectively. Cut points varied across studies. A significant majority of studies failed to report important CT technical parameters, such as use of intravenous contrast and slice thickness (94% and 63%, respectively).

CONCLUSIONS

There is considerable variation in the CT approaches used for the assessment of muscle mass and myosteatosis. There is a need to develop consensus for CT-based evaluation of sarcopenia and myosteatosis.

Tears in the distal superficial medial collateral ligament: the wave sign and other associated MRI findings

OBJECTIVE

To analyze the MRI characteristics of distal superficial medial collateral ligament (sMCL) tears and to identify features of tears displaced superficial to the pes anserinus (Stener-like lesion (SLL)).

MATERIALS AND METHODS

Knee MRI examinations at four institutions were selected which showed tears of the sMCL located distal to the joint line. MRIs were evaluated for a SLL, a wavy contour to the sMCL, and the location of the proximal sMCL stump. Additional coexistent knee injuries were recorded.

RESULTS

The study included 51 patients (mean age, 28 years [sd, 12]). A SLL was identified in 20 of 51 cases. The proximal stump margin was located significantly (p < 0.01) more distal and more medial with a SLL (mean = 33 mm [sd = 11 mm] and mean = 6.5 mm [sd = 2.5 mm], respectively), than without a SLL (mean = 19 mm [sd = 16 mm] and mean = 4.8 mm [sd = 2.4 mm], respectively). Medial compartment osseous injury was significantly (p < 0.05) more common with a SLL (75%) than without a SLL (42%). The frequency of concomitant injuries in the group (ACL tear, 82%; PCL tear, 22%; deep MCL tear, 61%; lateral compartment osseous injury, 94%) did not differ significantly between patients with and without a SLL.

CONCLUSION

A distal sMCL tear should be considered when MRI depicts a wavy appearance of the sMCL. Distal sMCL tears have a frequent association with concomitant knee injuries, especially ACL tears and lateral femorotibial osseous injuries. A SLL is particularly important to recognize because of implications for treatment.

Opportunistic Measurement of Skeletal Muscle Size and Muscle Attenuation on Computed Tomography Predicts 1-Year Mortality in Medicare Patients

BACKGROUND

Opportunistic assessment of sarcopenia on CT examinations is becoming increasingly common. This study aimed to determine relationships between CT-measured skeletal muscle size and attenuation with 1-year risk of mortality in older adults enrolled in a Medicare Shared Savings Program (MSSP).

METHODS

Relationships between skeletal muscle metrics and all-cause mortality were determined in 436 participants (52% women, mean age 75 years) who had abdominopelvic CT examinations. On CT images, skeletal muscles were segmented at the level of L3 using two methods: (a) all muscles with a threshold of -29 to +150 Hounsfield units (HU), using a dedicated segmentation software, (b) left psoas muscle using a free-hand region of interest tool on a clinical workstation. Muscle cross-sectional area (CSA) and muscle attenuation were measured. Cox regression models were fit to determine the associations between muscle metrics and mortality, adjusting for age, sex, race, smoking status, cancer diagnosis, and Charlson comorbidity index.

RESULTS

Within 1 year of follow-up, 20.6% (90/436) participants died. In the fully-adjusted model, higher muscle index and muscle attenuation were associated with lower risk of mortality. A one-unit standard deviation (SD) increase was associated with a HR = 0.69 (95% CI = 0.49, 0.96; p = .03) for total muscle index, HR = 0.67 (95% CI = 0.49, 0.90; p < .01) for psoas muscle index, HR = 0.54 (95% CI = 0.40, 0.74; p < .01) for total muscle attenuation, and HR = 0.79 (95% CI = 0.66, 0.95; p = .01) for psoas muscle attenuation.

CONCLUSION

In older adults, higher skeletal muscle index and muscle attenuation on abdominopelvic CT examinations were associated with better survival, after adjusting for multiple risk factors.

Abdominal muscle segmentation from CT using a convolutional neural network

CT is widely used for diagnosis and treatment of a variety of diseases, including characterization of muscle loss. In many cases, changes in muscle mass, particularly abdominal muscle, indicate how well a patient is responding to treatment. Therefore, physicians use CT to monitor changes in muscle mass throughout the patient's course of treatment. In order to measure the muscle, radiologists must segment and review each CT slice manually, which is a time-consuming task. In this work, we present a fully convolutional neural network (CNN) for the segmentation of abdominal muscle on CT. We achieved a mean Dice similarity coefficient of 0.92, a mean precision of 0.93, and a mean recall of 0.91 in an independent test set. The CNN-based segmentation method can provide an automatic tool for the segmentation of abdominal muscle. As a result, the time required to obtain information about changes in abdominal muscle using the CNN takes a fraction of the time associated with manual segmentation methods and thus can provide a useful tool in the clinical application.

Dynamic MRI of the wrist in less than 20 seconds: normal midcarpal motion and reader reliability

OBJECTIVE

To describe the normal motion pattern at the midcarpal compartment during active radial-ulnar deviation of the wrist using dynamic MRI, and to determine the observer performance for measurements obtained in asymptomatic volunteers.

METHODS

Dynamic MRI of 35 wrists in 19 asymptomatic volunteers (age mean 30.4 years, SD 8.6) was performed during active radial-ulnar deviation using a fast gradient-echo pulse sequence with 315 ms temporal resolution (acquisition time, 19 s). Two independent readers measured the transverse translation of the trapezium at the scaphotrapezium joint (STJ) and the capitate-to-triquetrum distance (CTD). Relationships between these measurements and laterality, sex, lunate type, and wrist kinematic pattern were evaluated.

RESULTS

At the STJ, the trapezium moved most in radial deviation, with an overall translation of 2.3 mm between ulnar and radial deviation. Mean CTD measurements were the greatest in ulnar deviation and varied 2.4 mm between ulnar and radial deviation. Mean CTD was greater in men than women in the neutral position (p = 0.019), and in wrists with type II lunate morphology during radial and ulnar deviation (p = 0.001, p = 0.014). There were no significant differences in trapezium translation or CTD with wrist laterality and kinematic pattern. Intraobserver and interobserver correlation coefficients were 0.97 and 0.87 for trapezium translation and 0.84 and 0.67 for CTD.

CONCLUSION

This study is the first to demonstrate the performance of dynamic MRI to quantify STJ motion and CTD. Dynamic MRI with a short acquisition time may be used as a tool to supplement static MRI in evaluation of the midcarpal compartment.

Machine Learning for Automatic Paraspinous Muscle Area and Attenuation Measures on Low-Dose Chest CT Scans

RATIONALE AND OBJECTIVES

To develop and evaluate an automated machine learning (ML) algorithm for segmenting the paraspinous muscles on chest computed tomography (CT) scans to evaluate for presence of sarcopenia.

MATERIALS AND METHODS

A convolutional neural network based on the U-Net architecture was trained to perform muscle segmentation on a dataset of 1875 single slice CT images and was tested on 209 CT images of participants in the National Lung Screening Trial. Low-dose, noncontrast CT examinations were obtained at 33 clinical sites, using scanners from four manufacturers. The study participants had a mean age of 71.6 years (range, 70-74 years). Ground truth was obtained by manually segmenting the left paraspinous muscle at the level of the T12 vertebra. Muscle cross-sectional area (CSA) and muscle attenuation (MA) were recorded. Comparison between the ML algorithm and ground truth measures of muscle CSA and MA were obtained using Dice similarity coefficients and Pearson correlations.

RESULTS

Compared to ground truth segmentation, the ML algorithm achieved median (standard deviation) Dice scores of 0.94 (0.04) in the test set. Mean (SD) muscle CSA was 14.3 (3.6) cm² for ground truth and 13.7 (3.5) cm² for ML segmentation. Mean (SD) MA was 41.6 (7.6) Hounsfield units (HU) for ground truth and 43.5 (7.9) HU for ML segmentation. There was high correlation between ML algorithm and ground truth for muscle CSA (r² = 0.86; p < 0.0001) and MA (r² = 0.95; p < 0.0001).

CONCLUSION

The ML algorithm for measurement of paraspinous muscles compared favorably to manual ground truth measurements in the NLST. The algorithm generalized well to a heterogeneous set of low-dose CT images and may be capable of automated quantification of muscle metrics to screen for sarcopenia on routine chest CT examinations.

Automated Segmentation of Tissues Using CT and MRI: A Systematic Review

RATIONALE AND OBJECTIVES

The automated segmentation of organs and tissues throughout the body using computed tomography and magnetic resonance imaging has been rapidly increasing. Research into many medical conditions has benefited greatly from these approaches by allowing the development of more rapid and reproducible quantitative imaging markers. These markers have been used to help diagnose disease, determine prognosis, select patients for therapy, and follow responses to therapy. Because some of these tools are now transitioning from research environments to clinical practice, it is important for radiologists to become familiar with various methods used for automated segmentation.

MATERIALS AND METHODS

The Radiology Research Alliance of the Association of University Radiologists convened an Automated Segmentation Task Force to conduct a systematic review of the peer-reviewed literature on this topic.

RESULTS

The systematic review presented here includes 408 studies and discusses various approaches to automated segmentation using computed tomography and magnetic resonance imaging for neurologic, thoracic, abdominal, musculoskeletal, and breast imaging applications.

CONCLUSION

These insights should help prepare radiologists to better evaluate automated segmentation tools and apply them not only to research, but eventually to clinical practice.

AUTOMATED MEASUREMENT OF MUSCLE DENSITY ON COMPUTED TOMOGRAPHY (CT) PREDICTS ALL-CAUSE MORTALITY IN OLDER ADULTS

The purpose was to examine the association of paraspinous muscle density (CT surrogate of myosteatosis) with all-cause mortality in 6803 men and 4558 women, age 60-69 years (mean age 63.6) in the National Lung Screening Trial. Our fully-automated machine learning algorithm: 1) selected the appropriate CT series, 2) chose a single CT image at the level of T12 vertebra, 3) segmented the left paraspinous muscle, and 4) recorded the muscle density in Hounsfield Units (HU). Association between baseline muscle density and all-cause mortality was determined using Cox proportional hazards models, adjusted for age, race, body mass index, pack years of smoking, and presence of diabetes, lung disease, cardiovascular disease, and cancer at enrollment. After a mean 6.44 ± 1.06 years of follow-up, 635 (9.33%) men and 265 (5.81%) women died. In men, lower muscle density on baseline CT examinations was associated with increased all-cause mortality (HR per SD = 0.90; CI = 0.83, 0.99; p=0.03). Each standard deviation (7.8 HU) decrease in muscle density was associated with a 10% increase in mortality. In women, the association did not reach significance.

Real-time three-dimensional MRI for the assessment of dynamic carpal instability

Background

Carpal instability is defined as a condition where wrist motion and/or loading creates mechanical dysfunction, resulting in weakness, pain and decreased function. When conventional methods do not identify the instability patterns, yet clinical signs of instability exist, the diagnosis of dynamic instability is often suggested to describe carpal derangement manifested only during the wrist’s active motion or stress. We addressed the question: can advanced MRI techniques provide quantitative means to evaluate dynamic carpal instability and supplement standard static MRI acquisition? Our objectives were to (i) develop a real-time, three-dimensional MRI method to image the carpal joints during their active, uninterrupted motion; and (ii) demonstrate feasibility of the method for assessing metrics relevant to dynamic carpal instability, thus overcoming limitations of standard MRI.

Methods

Twenty wrists (bilateral wrists of ten healthy participants) were scanned during radial-ulnar deviation and clenched-fist maneuvers. Images resulting from two real-time MRI pulse sequences, four sparse data-acquisition schemes, and three constrained image reconstruction techniques were compared. Image quality was assessed via blinded scoring by three radiologists and quantitative imaging metrics.

Results

Real-time MRI data-acquisition employing sparse radial sampling with a gradient-recalled-echo acquisition and constrained iterative reconstruction appeared to provide a practical tradeoff between imaging speed (temporal resolution up to 135 ms per slice) and image quality. The method effectively reduced streaking artifacts arising from data undersampling and enabled the derivation of quantitative measures pertinent to evaluating dynamic carpal instability.

Conclusion

This study demonstrates that real-time, three-dimensional MRI of the moving wrist is feasible and may be useful for the evaluation of dynamic carpal instability.

A principal component analysis-based framework for statistical modeling of bone displacement during wrist maneuvers

We present a method for the statistical modeling of the displacements of wrist bones during the performance of coordinated maneuvers, such as radial-ulnar deviation (RUD). In our approach, we decompose bone displacement via a set of basis functions, identified via principal component analysis (PCA). We utilized MRI wrist scans acquired at multiple static positions for deriving these basis functions. We then utilized these basis functions to compare the displacements undergone by the bones of the left versus right wrist in the same individual, and between bones of the wrists of men and women, during the performance of the coordinated RUD maneuver. Our results show that the complex displacements of the wrist bones during RUD can be modeled with high reliability with just 5 basis functions, that captured over 91% of variation across individuals. The basis functions were able to predict intermediate wrist bone poses with an overall high accuracy (mean error of 0.26 mm). Our proposed approach found statistically significant differences between bone displacement trajectories in women versus men, however, did not find significant differences in those of the left versus right wrist in the same individual. Our proposed method has the potential to enable detailed analysis of wrist kinematics for each sex, and provide a robust framework for characterizing the normal and pathologic displacement of the wrist bones, such as in the context of wrist instability.

Opportunistic Screening for Osteoporosis Using Computed Tomography: State of the Art and Argument for Paradigm Shift

PURPOSE OF REVIEW

Osteoporosis is disproportionately common in rheumatology patients. For the past three decades, the diagnosis of osteoporosis has benefited from well-established practice guidelines that emphasized the use of dual x-ray absorptiometry (DXA). Despite these guidelines and the wide availability of DXA, approximately two thirds of eligible patients do not undergo testing. One strategy to improve osteoporosis testing is to employ computed tomography (CT) examinations obtained as part of routine patient care to "opportunistically" screen for osteoporosis, without additional cost or radiation exposure to patients. This review examines the role of opportunistic CT in the evaluation of osteoporosis.

RECENT FINDINGS

Recent evidence suggests that opportunistic measurement of bone attenuation (radiodensity) using CT has sensitivity comparable to DXA. More importantly, such an approach has been shown to predict osteoporotic fractures. The paradigm shift of using CTs obtained for other reasons to opportunistically screen for osteoporosis promises to substantially improve patient care.