Scrutinizing the use of contrasted chest CTs in extremity sarcoma staging and surveillance.

BACKGROUND: Since 2015, the American College of Radiology (ACR) has recommended staging for lung metastasis via chest computed tomography (CT) without contrast for extremity sarcoma staging and surveillance. The purpose of this study was to determine our institutional compliance with this recommendation. METHODS: This was a retrospective chart review of patients diagnosed with sarcoma in the extremities who received CT imaging of the chest for pulmonary staging and surveillance at our institution from 2005 to 2023. A total of 1916 CT studies were included for analysis. We scrutinized ordering patterns before and after 2015 based on the ACR-published metastasis staging and screening guidelines. An institutional and patient cost analysis was performed between CT modalities. RESULTS: The prevalence of CT scans ordered and performed with contrast was greater than those without contrast both prior and post-ACR 2015 guidelines. Furthermore, 79.2% of patient's final surveillance CTs after 2015 were performed with contrast. A cost analysis was performed and demonstrated an additional $297 704 in patient and institutional costs. CONCLUSIONS: At our institution, upon review of CT chest imaging for pulmonary staging and surveillance in patients with extremity sarcoma the use of contrast has been routinely utilized despite a lack of evidence for its necessity and contrary to ACR guidelines.

Extremity radiographs derived from low-dose ultra-high-resolution CT: a phantom study.

OBJECTIVE: To demonstrate the potential of low-dose ultra-high-resolution CT (UHRCT) images to generate high-quality radiographic images on extremity phantoms and to estimate the radiation dose required for this. MATERIALS AND METHODS: A hand and knee phantom containing real human bones was imaged on an UHRCT scanner at full-dose, half-dose, and quarter-dose levels using a high-resolution extremity protocol. The raw data was reconstructed using both filtered back projection (FBP) and an iterative reconstruction algorithm (AIDR3D). Using custom designed software, each CT volume data set was converted to attenuation coefficients, and then a synthesized radiograph (synDX) was generated by forward projecting the volume data sets from a point source onto a 2D synthetic detector. The signal-to-noise ratio (SNR) was measured in the synDXs across all dose levels and the root-mean-squared error (RMSE) was computed with the FD synDXs as the reference. RESULTS: The proposed workflow generates high-quality synDXs at any arbitrary angle. For FBP, the SNR largely tracked with the radiation dose levels for both the knee and hand phantoms. For the knee phantom, iterative reconstruction provided a 6.1% higher SNR when compared to FBP. The RMSE was overall higher for the lowest dose levels and monotonically decreased with increasing dose. No substantial differences were observed qualitatively in the visualization of skeletal detail of the phantoms. CONCLUSION: The fine detail provided by UHRCT acquisitions of extremities facilitates the ability to generate quality radiographs, potentially eliminating the need for additional scanning on a conventional digital radiography system.

Sarcopenia and frailty as predictors of surgical morbidity and oncologic outcomes in retroperitoneal sarcoma.

BACKGROUND: Retroperitoneal sarcomas (RPS) are rare tumors for which surgical resection is the principal treatment. There is no established model to predict perioperative risks for RPS. We evaluated the association between preoperative sarcopenia, frailty, and hypoalbuminemia with surgical and oncological outcomes. METHODS: We performed a prospective cohort analysis of 65 RPS patients who underwent surgical resection. Sarcopenia was defined as Total Psoas Area Index ≤ 1st quintile by sex. Frailty was estimated using the modified frailty index (mFI). Logistic regression models were used to assess predictors of 30-day postoperative morbidity. The Kaplan-Meier method with log-rank test was utilized to assess factors associated with overall (OS) and recurrence-free survival (RFS). RESULT: Sarcopenia was associated with worse OS with a median of 54 compared with 158 months (p = 0.04), but no differences in RFS (p > 0.05). Hypoalbuminemia was associated with worse OS with a median of 72 compared with 158 months (p < 0.01). MFI scores were not associated with OS or RFS (p > 0.05). Sarcopenia, mFI, and hypoalbuminemia were not associated with postoperative morbidity (p > 0.05). CONCLUSION: This study suggests that sarcopenia may be utilized as a measure of overall fitness, rather than a cancer-specific risk, and the mFI is a poor predictive measure of outcomes in RPS.

AI-Based Automated Lipomatous Tumor Segmentation in MR Images: Ensemble Solution to Heterogeneous Data.

Deep learning (DL) has been proposed to automate image segmentation and provide accuracy, consistency, and efficiency. Accurate segmentation of lipomatous tumors (LTs) is critical for correct tumor radiomics analysis and localization. The major challenge of this task is data heterogeneity, including tumor morphological characteristics and multicenter scanning protocols. To mitigate the issue, we aimed to develop a DL-based Super Learner (SL) ensemble framework with different data correction and normalization methods. Pathologically proven LTs on pre-operative T1-weighted/proton-density MR images of 185 patients were manually segmented. The LTs were categorized by tumor locations as distal upper limb (DUL), distal lower limb (DLL), proximal upper limb (PUL), proximal lower limb (PLL), or Trunk (T) and grouped by 80%/9%/11% for training, validation and testing. Six configurations of correction/normalization were applied to data for fivefold-cross-validation trainings, resulting in 30 base learners (BLs). A SL was obtained from the BLs by optimizing SL weights. The performance was evaluated by dice-similarity-coefficient (DSC), sensitivity, specificity, and Hausdorff distance (HD95). For predictions of the BLs, the average DSC, sensitivity, and specificity from the testing data were 0.72 [Formula: see text] 0.16, 0.73 [Formula: see text] 0.168, and 0.99 [Formula: see text] 0.012, respectively, while for SL predictions were 0.80 [Formula: see text] 0.184, 0.78 [Formula: see text] 0.193, and 1.00 [Formula: see text] 0.010. The average HD95 of the BLs were 11.5 (DUL), 23.2 (DLL), 25.9 (PUL), 32.1 (PLL), and 47.9 (T) mm, whereas of SL were 1.7, 8.4, 15.9, 2.2, and 36.6 mm, respectively. The proposed method could improve the segmentation accuracy and mitigate the performance instability and data heterogeneity aiding the differential diagnosis of LTs in real clinical situations.

Ankle MRI and preceding radiographs: an evaluation of physician ordering practices.

OBJECTIVE: Multiple guidelines have been published for appropriate imaging in patients with ankle-related symptoms which suggest radiographs as the initial imaging examination for both acute and chronic ankle abnormalities. Few studies have evaluated adherence to these imaging guidelines. This study retrospectively evaluated the utilization of ankle MRI and preceding radiographs based on ordering provider group and MRI indication. MATERIALS AND METHODS: A total of 4186 ankle MRIs performed over a 9-year period at a single institution were evaluated for the presence of preceding ankle and/or foot radiographs at two time points, within 3 months and within 6 months of the MRI examination. Ankle MRIs were then categorized based on 6 ordering provider groups and 13 MRI indications. RESULTS: Of the 4186 MRIs evaluated, 68% had preceding radiographs within 3 months and 77% had radiographs within 6 months. Primary care, sports medicine, and podiatry had the lowest rates of preceding radiographs (73%, 68%, and 64%, respectively, within 6 months). Eighty-six percent of ankle MRIs ordered by orthopedic surgery had preceding radiographs within 6 months and 89% of ankle MRIs ordered by emergency medicine and inpatient providers had preceding radiographs. MRIs intended for evaluation of Achilles tendon or plantar fascia abnormalities were among the least likely indications to have preceding radiographs. CONCLUSION: Based on established clinical guidelines, there was a lower-than-expected rate of obtaining preceding radiographs for ankle MRIs among most provider groups, particularly non-orthopedic outpatient providers. Additional research is needed to address the lack of adherence to clinical imaging guidelines and ensure appropriate imaging.

Surgical and oncologic outcomes following arterial resection and reconstruction for advanced solid tumors.

BACKGROUND AND OBJECTIVES: Although arterial involvement for advanced tumors is rare, vascular resection may be indicated to achieve complete tumor resection. Given the potential morbidity of this approach, we sought to evaluate perioperative outcomes, vascular graft patency, and survival among patients undergoing tumor excision with en bloc arterial resection and reconstruction. METHODS: From 2010 to 2020, we identified nine patients with tumors encasing or extensively abutting major arterial structures for whom en bloc arterial resection and reconstruction was performed. RESULTS: Mean age was 53 ± 20 years, and 89% were females. Diagnoses were primary sarcomas (5), recurrent gynecologic carcinomas (3), and benign retroperitoneal fibrosis (1). Tumors involved the infrarenal aorta (2), iliac arteries (6), and superficial femoral artery (1). Three patients (33%) had severe perioperative morbidity (Grade III + ) with no mortality. At a median follow-up of 23 months, eight patients (89%) had primary graft patency, and five patients (56%) had no evidence of disease. CONCLUSIONS: Arterial resection and reconstruction as part of the multimodality treatment of regionally advanced tumors is associated with acceptable short- and long-term outcomes, including excellent graft patency. In appropriately selected patients, involvement of major arterial structures should not be viewed as a contraindication to attempted curative surgery.

The medial epicondyle of the distal femur is the optimal location for MRI measurement of semitendinosus and gracilis tendon cross-sectional area.

PURPOSE: Graft diameter ≥ 8 mm reduces the risk of failure after anterior cruciate ligament reconstruction (ALCR) with hamstring tendon autograft. Pre-operative measurement of gracilis (GT) and semitendinosus (ST) cross-sectional area using MRI has been utilized but the optimal location for measurement is unknown. The main purpose of this study was to examine the cross-sectional areas of GT + ST at different locations and develop a model to predict whether a doubled hamstring graft of GT + ST will be of sufficient cross-sectional area for ACLR. METHODS: A retrospective review was performed of 154 patients who underwent primary ACLR using doubled hamstring autograft. Cross-sectional area measurements of GT + ST on pre-operative MRI axial images were made at three locations: medial epicondyle (ME), tibiofemoral joint line (TJL), and tibial physeal scar (TPS) and calculated the correlation of intra-operative graft size for each location using the Pearson's correlation coefficient. A receiver operating characteristic (ROC) established a threshold that would predict graft diameter ≥ 8 mm. RESULTS: Measurement of GT + ST at the ME had a stronger correlation (r = 0.389) to intra-operative graft diameter than measurements at the TJL (r = 0.256) or TPS (r = 0.240). The ROC indicated good predictive value for hamstring graft diameter ≥ 8 mm based on MRI measurement at the ME with the optimal threshold with the highest sensitivity and specificity as 18 mm2. CONCLUSION: Cross-sectional area measurement of GT + ST at the ME correlated most closely to intra-operative diameter of a doubled hamstring autograft compared to measurements at the TJL or the TPS. As graft diameter < 8 mm is correlated with higher failure rates of ACL surgery, the ability to pre-operatively predict graft diameter is clinically useful. LEVEL OF EVIDENCE: Level III, prognostic study.

CT of Patients With Hip Fracture: Muscle Size and Attenuation Help Predict Mortality.

OBJECTIVE: Our objective was to determine the association between muscle cross-sectional area and attenuation, as measured on routine CT scans, and mortality in older patients with hip fracture. MATERIALS AND METHODS: A retrospective 10-year study of patients with hip fracture was conducted with the following inclusion criteria: age 65 years or older, first-time hip fracture treated with surgery, and CT of the chest, abdomen, or pelvis. This yielded 274 patients (70.4% women; mean [± SD] age, 81.3 ± 8.3 years). On each CT scan, two readers independently measured the size (cross-sectional area, indexed for patient height) and attenuation of the paravertebral muscle at T12 and the psoas muscle at L4. We then determined the association between overall mortality and the muscle size and muscle attenuation, while adjusting for demographic variables (age, sex, ethnicity, and body mass index), American Society of Anesthesiologists (ASA) classification, and Charlson comorbidity index (CCI). RESULTS: The overall mortality rate increased from 28.3% at 1 year to 79.5% at 5 years. Mortality was associated with decreased thoracic muscle size (odds ratio [OR], 0.66; 95% CI, 0.49-0.87). This association persisted after adjusting for demographic variables (OR, 0.69; 95% CI, 0.50-0.95), the ASA classification (OR, 0.70; CI, 0.51-0.97), and the CCI (OR, 0.72; 95% CI, 0.52-1.00). Similarly, decreased survival was associated with decreased thoracic muscle attenuation after adjusting for all of these combinations of covariates (OR, 0.67-0.72; 95% CI, 0.49-0.99). Decreased lumbar muscle size and attenuation trended with decreased survival but did not reach statistical significance. CONCLUSION: In older adults with hip fractures, CT findings of decreased thoracic paravertebral muscle size and attenuation are associated with decreased overall survival.

"Knuckle Cracking": Can Blinded Observers Detect Changes with Physical Examination and Sonography?

BACKGROUND: Voluntary knuckle cracking is a common habit, with a reported prevalence of 25% to 45%. Habitual knuckle cracking also is a frequent source of questions for physicians, and the largest study to date reported an association with functional hand impairments. QUESTIONS/PURPOSES: (1) When compared with subjects who are not habitual knuckle crackers, do habitual knuckle crackers have greater QuickDASH scores, swelling, weakness, joint laxity, or ROM? (2) In subjects who crack their knuckles, does cracking immediately increase ROM? (3) What are the characteristic sonographic findings in joints that crack? METHODS: A prospective, institutional review board-approved study was performed on 400 metacarpophalangeal joints (MPJs) in 40 asymptomatic adult subjects. Of those, 30 subjects had a history of habitual knuckle cracking (defined as daily voluntary popping of MPJs). Clinical history provided by all subjects included a standardized QuickDASH questionnaire. Physical examination was performed by two orthopaedic surgeons (blinded to subjects' knuckle-cracking history and sonographic outcomes). The physical examination included evaluation for swelling, grip strength, and ROM before and after attempted knuckle cracking. Sonographic examination was conducted by one sonographer, with static and real-time cine images recorded before, during, and after MPJ distraction was performed by the subjects. Two musculoskeletal radiologists (blinded to subjects' knuckle-cracking history) interpreted the images for a definite hyperechoic focus during and after MPJ distraction; this was compared against the reference standard of an audible "crack" during joint distraction. RESULTS: Comparing subjects with knuckle cracking with those who did not crack their knuckles, there was no differences in QuickDASH scores (knuckle crackers, 3.7 ± 5.2; nonknuckle crackers, 3.2 ± 6.3; mean difference, 0.6; 95% CI, -3.5 to 4.6; p = 0.786), laxity (knuckle crackers, 2.0 ± 1.8; nonknuckle crackers, 0.3 ± 0.7; mean difference, 1.7; 95% CI, 0.5-2.9; p = 0.191), and grip strength (preultrasound, right hand, p = 0.499, left hand p = 0.575; postultrasound, right hand p = 0.777, left hand p = 0.424); ROM comparisons between subjects with a history of habitual knuckle cracking versus subjects without such a history only yielded increased ROM in joints that cracked during manipulation (knuckle cracking, 143.8° ± 26.5°; nonknuckle cracking, 134.9° ± 28.6°; mean difference, 9.0°; 95% CI, 2.9°-15.1°; p = 0.004). Swelling was not observed in any subjects, including when comparing MPJs before versus after distraction maneuvers that resulted in audible cracks. Immediately after a documented crack, there were greater ranges of motion with active flexion (preultrasound, 85.7° ± 12.4°; postultrasound, 88.6° ± 11.6°; mean difference, -2.9°; 95% CI, -5.1° to -0.8°; p = 0.009), passive flexion (preultrasound, 96.1° ± 12.4°; postultrasound, 100.3° ± 10.4°; mean difference, -4.3°; 95% CI, -6.2° to -2.3°; p < 0.001), passive extension (preultrasound, 41.8° ± 18.1°; postultrasound, 45.2° ± 17.6°; mean difference, -3.5°; 95% CI, -6.9° to -0.1°; p = 0.046), and passive total ROM (preultrasound, 137.8° ± 24.8°; postultrasound, 145.6° ± 23.1°; mean difference, -7.7°; 95% CI, -11.7° to -3.8°; p < 0.001). The characteristic sonographic finding observed during cracking events is an echogenic focus that appears de novo dynamically in the joint during distraction. CONCLUSIONS: We found no evidence of immediate adverse physical examination findings after knuckle cracking. However, we did find a small increase in ROM among joints that cracked compared with those that did not. Future studies should examine if there are any long-term beneficial and adverse clinical outcomes associated with habitual knuckle cracking. LEVEL OF EVIDENCE: Level I, prognostic study.

Influence of IV Contrast Administration on CT Measures of Muscle and Bone Attenuation: Implications for Sarcopenia and Osteoporosis Evaluation.

OBJECTIVE: The objective of our study was to characterize enhancement of muscle and bone that occurs on standardized four-phase contrast-enhanced CT. MATERIALS AND METHODS: Two musculoskeletal radiologists reviewed standardized four-phase abdominal CT scans obtained with IV contrast material. The psoas area was measured, and the mean attenuation (in Hounsfield units) was recorded for the aorta, psoas muscles, posterior paraspinal muscles, and L4 vertebral body. CT attenuation measures were compared between anatomic regions and imaging phases with the paired t test; associations between measures were examined with the Pearson correlation coefficient (R). RESULTS: The study included 201 patients (97 men, 104 women; mean age, 57.7 ± 12.5 [SD] years). Subject age was inversely correlated with unenhanced attenuation in the psoas muscles, posterior paraspinal muscles, and L4 (p < 0.001). The psoas muscles, posterior paraspinal muscles, and L4 enhanced significantly (p < 0.001) at all three contrast-enhanced phases. The greatest muscle enhancement was observed on delayed phase scans, whereas the greatest enhancement in L4 was seen on portal phase imaging. The unenhanced attenuation of the psoas muscles was significantly and negatively correlated with enhancement of the psoas muscles at the portal and delayed phases (p < 0.05 and p < 0.01, respectively), but these correlations were not seen for the posterior paraspinal muscles. Age was positively correlated with posterior paraspinal muscle enhancement at the portal and delayed phases in men (p < 0.05 and p < 0.01, respectively) but not in women. CONCLUSION: Contrast enhancement of commonly measured muscle and bone regions is routinely observed and should be considered when using CT attenuation values as biomarkers of sarcopenia and osteoporosis. Furthermore, CT enhancement may be significantly influenced by age, sex, and unenhanced tissue attenuation.

The Notch of Harty (Pseudodefect of the Tibial Plafond): Frequency and Characteristic Findings at MRI of the Ankle.

OBJECTIVE: The purpose of this study is to report the frequency and characteristic findings of the notch of Harty as seen on MRI. MATERIALS AND METHODS: One hundred six consecutive ankle MRI studies performed at 1.5 or 3 T were reviewed retrospectively by two radiologists. Findings relating to the notch of Harty and ankle joint were recorded and analyzed, including qualitative assessment of the presence of the notch, focal chondral thinning or focal subcortical osteosclerosis at the notch, notch width and depth, osteochondral lesions elsewhere in the ankle, subchondral edema signal or cystic change at the tibial plafond, and the presence of an ankle joint effusion. RESULTS: The study group of 106 patients consisted of 48 male and 58 female patients, with a mean age of 44.5 years (SD, 17.5 years). The notch was identified in 48 of 106 patients (45%) (24 male and 24 female patients; mean age, 43.1 years; range, 7-79 years). When present, the notch averaged 6.2 mm (SD, 1.6 mm) in width and 1.2 mm (SD, 0.5 mm) in depth. The notch was graded as prominent in six of the 106 ankle MRI examinations (6%). Subchondral edemalike signal or cystic change was not localized to the notch in any case. Between patients with versus those without a notch, there was no statistically significant difference in age, sex, subjacent subcortical osteosclerosis, ankle joint effusion, osteochondral lesions elsewhere in the ankle, or subchondral bone marrow edema at the tibial plafond. CONCLUSION: The notch of Harty can be observed as an anatomic variant on MRI and should be differentiated from a traumatic osteochondral lesion.

Imaging key wrist ligaments: what the surgeon needs the radiologist to know.

OBJECTIVE: Although much attention is paid to the scapholunate ligament, lunotriquetral ligament, and the triangular fibrocartilage complex, additional intrinsic and extrinsic ligaments in the wrist play an important part in carpal stability. With improved MRI techniques, the radiologist can increasingly visualize these ligaments. CONCLUSION: The anatomy, MRI appearance, and clinical significance of the scapholunate ligament, lunotriquetral ligament, triangular fibrocartilage complex, carpal metacarpal ligaments, and volar and dorsal extrinsic ligaments are reviewed.

A rare case of chondroblastoma involving the distal phalanx of the ring finger.

Chondroblastoma, a rare benign bone tumor, is typically found in the epiphysis of long bones, with hand involvement being particularly uncommon. We present a case of an 11-year-old female with chondroblastoma involving the fourth distal phalanx of the hand. Imaging revealed a lytic, expansile lesion with sclerotic margins and no soft tissue component. A preoperative differential diagnosis included intraosseous glomus tumor, epidermal inclusion cyst, enchondroma, and chronic infection. The patient underwent open surgical biopsy and curettage for both diagnostic and treatment purpose. The final histopathologic diagnosis was chondroblastoma.

Recurrent chondroblastoma of the acetabulum in an adult.

Chondroblastoma is a rare, benign neoplasm of chondroblast cell origin, accounting for less than 1% of primary bone tumors. It is usually diagnosed in the second decade of life with most of the cases involving the long bones such as the femur and humerus. Furthermore, over 90% of cases are in individuals under 30 years of age. In older adults, chondroblastomas are typically found in bones in the foot, such as the talus and calcaneus. Treatment is usually local curettage of the lesion with a relatively low rate of recurrence. In this case report, we present a patient with an atypical age of initial presentation at 49 years, a rare location of the chondroblastoma in the acetabulum, and a recurrence 14 years after surgical resection in the same location. The lesion's radiographic findings of intralesional calcifications alongside the high-signal, heterogeneous composition on T2-weighted MRI were supportive of the atypical diagnosis of chondroblastoma in this patient.

Radiology residents' experience with intussusception reduction.

BACKGROUND: Residents should be exposed to adequate procedural volume to act independently upon completion of training. Informal inquiry led us to question whether residents encounter enough intussusception reductions to become comfortable with the procedure. OBJECTIVE: We sought to determine radiology residents' exposure to intussusception reductions, and whether their experiences vary by region or institution. MATERIALS AND METHODS: U.S. radiology residency program directors were asked to encourage their residents to complete a 12-question online survey describing characteristics of their pediatric radiology department, experiences with intussusception reduction, and confidence in their own ability to perform the procedure. RESULTS: Six hundred sixty-four residents responded during the study period. Of those, 308 (46.4%) had not experienced an intussusception reduction, and 228 (34%) had experienced only one or two. Twenty-two percent of fourth-year residents had never experienced an intussusception reduction, and 21% had experienced only one. Among second- through fourth-year residents, only 99 (18.3%) felt confident that they could competently reduce an intussusception (P < 0.0001), and 336 (62.2%) thought they would benefit from a computer-assisted training model simulating intussusception reduction (P < 0.0001). CONCLUSION: Radiology residents have limited opportunity to learn intussusception reduction and therefore lack confidence. Most think they would benefit from additional training with a computer-simulation model.

Pediatric radiology fellows' experience with intussusception reduction.

BACKGROUND: Intussusception reduction allows young children to avoid surgery. However, graduating residents have had relatively little training in intussusception reduction and, for the most part, consider themselves ill-prepared to perform this procedure. OBJECTIVE: The goal of this study was to assess the extent of training in intussusception reduction during one year of a pediatric radiology fellowship and to determine whether graduating fellows consider themselves adequately trained in this technique. MATERIALS AND METHODS: Pediatric radiology fellows were surveyed during June 2010 and asked to characterize their fellowship, to indicate the number of intussusception reductions performed (both the total number and those performed with faculty oversight but without active faculty involvement), and to assess the adequacy of their training. RESULTS: There were 31 responses, representing almost 1/3 of current fellows. Pediatric radiology fellows perform on average 6.9 reductions, 3.8 of which are with faculty oversight but without active faculty involvement. Ninety percent consider themselves well-trained in the technique, whereas 10% are uncertain (none consider their training inadequate). CONCLUSION: Almost all pediatric radiology fellows consider their training in intussusception reduction to be adequate.

Polyostotic osteoid osteoma: A case report.

Osteoid osteomas are common, benign osteoblastic tumors that can occur in any bone in the body. They are almost always solitary, with only rare reports of multiple tumors in the same patient. When multiple, they typically are found within the same bone. We present a unique case of a young female athlete who presented initially at 16 years old with a right tibial osteoid osteoma and later at 18 years old with a right acetabular osteoid osteoma. Our case demonstrates the rare entity of polyostotic osteoid osteoma, the potential limitations of MRI in the diagnosis of osteoid osteoma, and the utility of radiofrequency ablation in the treatment of osteoid osteoma.

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.

Radiographic Evaluation of Meniscal Extrusion.

Background Magnetic resonance imaging (MRI) is well established as the preferred noninvasive tool for meniscal evaluation. To our knowledge, there has been no study examining the utility of diagnosing meniscal extrusion from radiography alone. We hypothesize that with appropriate window settings, meniscal extrusion may be diagnosed on radiography with high sensitivity and specificity. Materials and methods We included 190 patients with MRI of the knee performed within three months of knee radiography. As defined within the literature, we utilized the MRI criteria of meniscal extrusion as meniscal tissue extending 3 mm or greater beyond the tibial plateau, excluding osteophytes. Two attending radiologists blindly and independently identified the absence or presence, in millimeters, of medial meniscal extrusion on plain film radiography. Kappa test and Pearson correlation coefficient were calculated to assess the extent of inter-reader agreement and correlation. Sensitivity and specificity were calculated for each reader, assuming the concurrent MRI served as the gold standard. Results Ninety-six patients had medial meniscal extrusion and 94 had no medial extrusion by MRI. Kappa test for inter-reader agreement = 0.61. Pearson coefficient for inter-reader measurement correlation = 0.69. Reader A had sensitivity of 0.59 (95% CI 0.49-0.69) and specificity of 0.88 (95% CI 0.79-0.94). Reader B had sensitivity of 0.61 (95% CI 0.51-0.71) and specificity of 0.85 (95% CI 0.76-0.91). Conclusion There is substantial inter-reader agreement and high correlation of meniscal extrusion measurement between readers. Our results suggest that while radiographs have low sensitivity for evaluation of meniscal extrusion, their high specificity may be of clinical utility.

Retroperitoneal extramedullary hematopoietic pseudotumor in ataxia-telangiectasia.

Ataxia-telangiectasia confers a significant increase in the development of several cancer types, most commonly leukemia and lymphoma. However, as the natural history for these patients is evolving and their lifespan is increasing, there is the potential for the development of additional uncommon tumors in an already rare patient population. We report the first case, to our knowledge, of an incidental retroperitoneal tumor in a 26-year-old woman undergoing evaluation for hepatic dysfunction. The mass was suspicious for retroperitoneal sarcoma, but proved to be an extramedullary hematopoietic pseudotumor after extensive pathologic evaluation. The changing landscape of neoplasms associated with ataxia-telangiectasia is discussed with emphasis on previously underreported benign and malignant tumors.