Radiologists should use the hip-knee-ankle angle rather than the mechanical axis deviation to describe knee alignment.

OBJECTIVE: Preoperative and postoperative coronal knee alignment is an important predictor of total knee arthroplasty (TKA) failure. Radiologists often report the mechanical axis deviation (MAD) rather than hip-knee-ankle angle (HKAA) to describe coronal knee alignment. The aim of this study is to evaluate (i) how well the MAD predicts the HKAA; (ii) if patient height and sex affect the performance of the MAD; and (iii) if the MAD could be measured faster than the HKAA. MATERIALS AND METHODS: Two hundred patients undergoing hip-to-ankle radiographs for TKA planning were retrospectively reviewed. The MAD and HKAA were measured using previously published methods by the Visage picture archiving and communication systems (PACS) tools. Receiver operator characteristic (ROC) curves were used to evaluate the performance of the MAD to predict HKAA by gender and height. The performance of a linear model was used to predict HKAA from MAD in a prospectively collected cohort of 40 patients. Paired t tests were used for the comparison of time measurement in MAD and HKAA in this cohort. RESULTS: MAD strongly correlated with HKAA (r = 0.99, p < 0.001); however, the performance of MAD differed by height (p = 0.005) and sex (p < 0.001). There was no significant difference in the time taken to measure HKAA versus MAD (p > 0.05). CONCLUSION: HKAA should be used instead of the MAD because it is more clinically relevant and takes the same amount of time to be measured.

Society of Skeletal Radiology- white paper. Guidelines for the diagnostic management of incidental solitary bone lesions on CT and MRI in adults: bone reporting and data system (Bone-RADS).

The purpose of this article is to present algorithms for the diagnostic management of solitary bone lesions incidentally encountered on computed tomography (CT) and magnetic resonance (MRI) in adults. Based on review of the current literature and expert opinion, the Practice Guidelines and Technical Standards Committee of the Society of Skeletal Radiology (SSR) proposes a bone reporting and data system (Bone-RADS) for incidentally encountered solitary bone lesions on CT and MRI with four possible diagnostic management recommendations (Bone-RADS1, leave alone; Bone-RADS2, perform different imaging modality; Bone-RADS3, perform follow-up imaging; Bone-RADS4, biopsy and/or oncologic referral). Two algorithms for CT based on lesion density (lucent or sclerotic/mixed) and two for MRI allow the user to arrive at a specific Bone-RADS management recommendation. Representative cases are provided to illustrate the usability of the algorithms.

Radiology-pathology correlation for bone and soft tissue tumors or tumor-like masses: single institutional experience after implementation of a weekly conference.

OBJECTIVES: To determine the frequency of non-diagnostic and discordant results from bone and soft tissue biopsies performed at our institution over a 3-year period and to investigate whether implementation of a weekly musculoskeletal radiology-pathology correlation conference decreased the time to appropriate patient management in cases of discordance. METHODS: Consecutive image-guided core needle biopsy results obtained over a 12 month period of time were reviewed in a retrospective fashion. Following implementation of the correlation conference, subsequent consecutive image-guided core needle biopsy results obtained over a 26 month period of time were reviewed in a prospective fashion. For non-diagnostic and discordant cases, the time in days from date of availability of the biopsy result to date of documentation of a specific follow-up action plan was recorded. RESULTS: Diagnostic yield was 96.5% and 94.9% for the retrospective and prospective periods, respectively. There were four discordant results in the retrospective cohort (1.7%) and seven discordant results in the prospective cohort (2.1%). Following implementation of the weekly correlation conference, there was significant decrease (p < 0.05) in median time from a discordant biopsy result to follow-up action plan. There were no unnecessary surgeries, litigation, or other unfavorable consequences in either cohort. CONCLUSION: Image-guided core needle biopsies of bone and soft tissue provide high diagnostic yield, often with specific diagnoses. The statistically significant decrease in number of days to follow-up action plan for discordant results suggests radiology-pathology review has a positive impact on patient care. Subjective benefits from communication and educational standpoints are also noteworthy.

Preoperative radioactive seed localization of nonpalpable soft tissue masses: an established localization technique with a new application.

OBJECTIVE: To describe the technique of iodine125 (I125) seed deployment into nonpalpable soft tissue masses under direct ultrasound (US) or CT guidance for intraoperative localization. MATERIALS AND METHODS: Patients considered candidates for radioactive seed localization (RSL) based on advanced imaging findings underwent an ultrasound examination of the area of concern to verify sonographic visualization of the targeted mass. If the mass was not visible sonographically, CT was used for guidance. Patients were scheduled for surgery 1-4 days after seed implantation. Intraoperative frozen section pathological analysis was performed on all patients. Operative time, specimen volume, intraoperative margin status, and final margin status were recorded. Following the surgery, patients and surgeons completed satisfaction surveys. RESULTS: Ten patients underwent seed placement between 1 and 4 days prior to surgery. All patients had successful surgical resection of the targeted mass with removal of all implanted radioactive seed(s). There was no seed migration. Intraoperative frozen-section margins were negative (>2 mm) in 6/10 patients. Final surgical margins were negative in 9/10 patients. The patient with a positive margin at final pathology did not undergo further resection due to the benign nature of the mass. Patient and surgeon satisfaction survey results were highly positive. All four surgeons reported a strong preference for seed localization over wire localization. CONCLUSIONS: RSL is an effective, reliable, and safe technique for preoperative localization of nonpalpable soft tissue masses and yields high patient and surgeon satisfaction.

Photocatalytic Hydrogen Generation by CdSe/CdS Nanoparticles.

The photocatalytic hydrogen (H2) production activity of various CdSe semiconductor nanoparticles was compared including CdSe and CdSe/CdS quantum dots (QDs), CdSe quantum rods (QRs), and CdSe/CdS dot-in-rods (DIRs). With equivalent photons absorbed, the H2 generation activity orders as CdSe QDs ≫ CdSe QRs > CdSe/CdS QDs > CdSe/CdS DIRs, which is surprisingly the opposite of the electron-hole separation efficiency. Calculations of photoexcited surface charge densities are positively correlated with the H2 production rate and suggest the size of the nanoparticle plays a critical role in determining the relative efficiency of H2 production.

Accuracy and Validity of Goniometer and Visual Assessments of Angular Joint Positions of the Hand and Wrist.

PURPOSE: To compare goniometric and visual assessments of angular hand joint and wrist joint positions measured by board-certified hand surgeons and certified hand therapists. We hypothesized that visual estimation would be similar to the goniometric measurement accuracy of digital and wrist joint positions. METHODS: The wrist, index finger metacarpophalangeal (MCP) joint, and index finger proximal interphalangeal (PIP) joint were evaluated in different positions by 40 observers: 20 board-certified hand surgeons and 20 certified hand therapists. Each observer estimated the position of the wrist, index MCP joint, and index PIP joint of the same volunteer, who was positioned in low-profile orthoses to reproduce predetermined positions. Following visual estimation, the participants measured the same joint positions using a goniometer. The control measurement was digitally determined by a radiologist who obtained radiographs of the hand and wrist positions in each orthosis. Observers were blinded to the results of control measurements. RESULTS: When considering all joints at all positions, neither visual assessments nor goniometer assessments were consistently within ± 5° of the measurements obtained on control radiographs. When considering individual joints, goniometer measurements were significantly closer to control radiograph measurements than the visual assessments for all 3 PIP joint positions. There was no difference for the measurements at the wrist or for 2 of the 3 MCP joint positions. Significant differences between surgeon and therapist joint angle measurements were not observed when comparing visual and goniometer assessments to radiograph controls. CONCLUSIONS: Compared with radiograph measurements, neither visual nor goniometer assessment displayed high levels of accuracy. On average, visual assessment of the angular positions of the index MCP and wrist joint were as accurate as the goniometer assessment, whereas goniometer assessment of the angular position of the PIP joint was more accurate than visual assessment. There was a relatively high degree of between-observer variability in measurements, and therefore, no one person's measurements could be consistently relied upon to be accurate. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

The influence of continuous vs. pulsed laser excitation on single quantum dot photophysics.

The impact of pulsed versus continuous wave (cw) laser excitation on the photophysical properties of single quantum dots (QDs) has been investigated in an experiment in which all macroscopic variables are identical except the nature of laser excitation. Pulsed excitation exaggerates the effects of photobleaching, results in a lower probability of long ON fluorescence blinking events, and leads to shorter fluorescence lifetimes with respect to cw excitation at the same wavelength and average intensity. Spectral wandering, biexciton quantum yields, and power law exponents that describe fluorescence blinking are largely insensitive to the nature of laser excitation. These results explicitly illustrate important similarities and differences in fluorescence dynamics between pulsed and cw excitation, enabling more meaningful comparisons between literature reports and aiding in the design of new experiments to mitigate possible influences of high photon flux on QDs.

Sclerosing variant of well-differentiated liposarcoma: relative prevalence and spectrum of CT and MRI features.

OBJECTIVE: The purpose of this study was to determine the relative prevalence of the sclerosing variant of well-differentiated liposarcoma at one institution and to elucidate the CT and MRI characteristics of this subtype of well-differentiated liposarcoma. MATERIALS AND METHODS: A retrospective computerized search was conducted to calculate the relative prevalence of the sclerosing variant of well-differentiated liposarcoma among all well-differentiated liposarcoma subtypes at one institution. The MRI and CT features of a total of 19 cases of pathologically proven sclerosing variant of well-differentiated liposarcoma were evaluated (seven identified from the study institution database and 12 cases contributed by other institutions). RESULTS: The cases of a total of 36 patients with well-differentiated liposarcoma were identified in the pathology database; six (17%) cases had evidence of dedifferentiation. Seven (19%) cases of sclerosing variant of well-differentiated liposarcoma were identified. Of these, three (43%) had evidence of dedifferentiation. On images, the sclerosing variant of well-differentiated liposarcoma typically presented as a large (average, 16.6 cm) well-circumscribed heterogeneous mass most commonly situated in the retroperitoneum (58%). Sixteen of the 19 tumors evaluated (84%) had predominantly well-circumscribed margins. Tumor composition ranged from predominantly fatty to entirely devoid of macroscopic fat; only three (16%) were composed of more than 75% fat. Variable amounts of nonlipomatous elements were identified in all cases. Enhancement of these elements was evident at CT or MRI in all 14 cases in which enhancement could be reliably assessed. CONCLUSION: The sclerosing variant of well-differentiated liposarcoma should be included in the differential diagnosis of any well-circumscribed lipomatous mass containing variable amounts of nonlipomatous elements, particularly when located in the retroperitoneum. Unlike other subtypes of well-differentiated liposarcoma, the sclerosing variant is less likely to be composed predominantly of fat and may be associated with an increased propensity for dedifferentiation.

Detecting whether L1 or other lumbar levels would be excluded from DXA bone mineral density analysis during opportunistic CT screening for osteoporosis using machine learning.

PURPOSE: One or more vertebrae are sometimes excluded from dual-energy X-ray absorptiometry (DXA) analysis if the bone mineral density (BMD) T-score estimates are not consistent with the other lumbar vertebrae BMD T-score estimates. The goal of this study was to build a machine learning framework to identify which vertebrae would be excluded from DXA analysis based on the computed tomography (CT) attenuation of the vertebrae. METHODS: Retrospective review of 995 patients (69.0% female) aged 50 years or greater with CT scans of the abdomen/pelvis and DXA within 1 year of each other. Volumetric semi-automated segmentation of each vertebral body was performed using 3D-Slicer to obtain the CT attenuation of each vertebra. Radiomic features based on the CT attenuation of the lumbar vertebrae were created. The data were randomly split into training/validation (90%) and test datasets (10%). We used two multivariate machine learning models: a support vector machine (SVM) and a neural net (NN) to predict which vertebra(e) were excluded from DXA analysis. RESULTS: L1, L2, L3, and L4 were excluded from DXA in 8.7% (87/995), 9.9% (99/995), 32.3% (321/995), and 42.6% (424/995) patients, respectively. The SVM had a higher area under the curve (AUC = 0.803) than the NN (AUC = 0.589) for predicting whether L1 would be excluded from DXA analysis (P = 0.015) in the test dataset. The SVM was better than the NN for predicting whether L2 (AUC = 0.757 compared to AUC = 0.478), L3 (AUC = 0.699 compared to AUC = 0.555), or L4 (AUC = 0.751 compared to AUC = 0.639) were excluded from DXA analysis. CONCLUSIONS: Machine learning algorithms could be used to identify which lumbar vertebrae would be excluded from DXA analysis and should not be used for opportunistic CT screening analysis. The SVM was better than the NN for identifying which lumbar vertebra should not be used for opportunistic CT screening analysis.

Mass-like extramedullary hematopoiesis: imaging features.

PURPOSE: To report the imaging appearances of mass-like extramedullary hematopoiesis (EMH), to identify those features that are sufficiently characteristic to allow a confident diagnosis, and to recognize the clinical conditions associated with EMH and the relative incidence of mass-like disease. MATERIALS AND METHODS: We retrospectively identified 44 patients with EMH; 12 of which (27%) had focal mass-like lesions and formed the study group. The study group consisted of 6 male and 6 female subjects with a mean age of 58 years (range 13-80 years). All 12 patients underwent CT imaging and 3 of the 12 patients had undergone additional MR imaging. The imaging characteristics of the extramedullary hematopoiesis lesions in the study group were analyzed and recorded. The patient's clinical presentation, including any condition associated with extramedullary hematopoiesis, was also recorded. RESULTS: Ten of the 12 (83%) patients had one or more masses located along the axial skeleton. Of the 10 patients with axial masses, 9 (90%) had multiple masses and 7 (70%) demonstrated internal fat. Eight patients (80%) had paraspinal masses and 4 patients (40%) had presacral masses. Seven patients (70%) had splenomegaly. Eleven of the 12 patients had a clinical history available for review. A predisposing condition for extramedullary hematopoiesis was present in 10 patients and included various anemias (5 cases; 45%), myelofibrosis/myelodysplastic syndrome (4 cases; 36%), and marrow proliferative disorder (1 case; 9%). One patient had no known predisposing condition. CONCLUSION: Mass-like extramedullary hematopoiesis most commonly presents as multiple, fat-containing lesions localized to the axial skeleton. When these imaging features are identified, extramedullary hematopoiesis should be strongly considered, particularly when occurring in the setting of a predisposing medical condition.

Shoulder Osteoarthritis.

Glenohumeral osteoarthritis has proven to be a major contributor to shoulder joint pain and dysfunction in the elderly. There are several conditions about the shoulder that contribute to the development of glenohumeral osteoarthritis, which includes traumatic injuries, rotator cuff pathology, glenohumeral instability, glenoid dysplasia, and osteonecrosis. When glenohumeral osteoarthritis pain is refractory to conservative treatment, intra-articular injections and surgery can be performed. The radiologist should be aware of the varying types of shoulder arthroplasties, what preoperative findings influence that decision and the expected postoperative appearance of the differing components.

Imaging characteristics of benign, malignant, and infectious jaw lesions: a pictorial review.

OBJECTIVE: The purpose of this article is to describe the indications and appropriate imaging studies for various jaw tumors and tumorlike lesions, the imaging findings, the differential diagnosis, and appropriate treatment options. CONCLUSION: It is important for radiologists to recognize the indications and appropriate imaging studies for various jaw lesions. Radiography is typically used for first-line imaging. If necessary, it is followed by CT for evaluation of osseous lesions and MRI for characterization of soft-tissue lesions.

Clinical utility of dual-energy CT for evaluation of tophaceous gout.

Although diagnosing gout generally is straightforward, atypical disease may present a challenge if it is associated with unusual symptoms or sites, discordant serum urate level, or mimics of gout. Dual-energy computed tomography (CT) may be used to differentiate urate crystals from calcium by using specific attenuation characteristics, which may help diagnose gout. In patients with known tophaceous gout, dual-energy CT may be used for serial volumetric quantification of subclinical tophi to evaluate response to treatment. Given the utility of dual-energy CT in challenging cases and its ability to provide an objective outcomes measure in patients with tophaceous gout, dual-energy CT promises to be a unique and clinically relevant modality in the diagnosis and management of gout.

Imaging spectrum of bites, stings, and their complications: pictorial review.

OBJECTIVE: Soft-tissue injuries from animal bites and insect stings are frequent causes of emergency department visits. Although many cases follow a short and benign clinical course, life-threatening complications can occur. Imaging can play an important role in guiding clinical care by revealing the scope of the injury and associated complications. The purpose of this article is to provide a brief overview of the epidemiology of animal-related injuries, with a focus on imaging manifestations of soft-tissue injury using multiple techniques in a pictorial review format. CONCLUSION: This article reviews the imaging manifestations of soft-tissue injuries caused by animal bites and insect stings. After completing this article, the reader should have an improved ability to recognize complications of soft-tissue injuries and the role of advanced imaging in select cases.

Imaging spectrum of bites, stings, and their complications: self-assessment module.

The educational objectives for this self-assessment module are for the participant to exercise, self-assess, and improve his or her understanding of the imaging spectrum of bites, stings, and their complications.

Pediatric FDG PET/CT: Physiologic uptake, normal variants, and benign conditions [corrected].

Ewing sarcoma family tumors account for approximately 3% of all pediatric cancers, making them the second most common bone malignancies in children and adolescents. Advances in the treatment of localized disease have dramatically prolonged the survival of patients in whom Ewing sarcoma is diagnosed, but the prognosis for patients with metastatic or recurrent disease remains poor. Radiologic evaluation of Ewing sarcoma can help (a) detect and accurately assess the extent of disease prior to treatment, (b) determine whether metastatic or recurrent disease is present, and (c) monitor therapy response. Standard imaging evaluation of bone and soft-tissue sarcomas typically consists of conventional radiography, magnetic resonance (MR) imaging, computed tomography (CT), and bone scintigraphy. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) provides unique information with regard to the biologic activity of Ewing sarcomas. It represents a noninvasive means of estimating histologic tumor grade and can be used to detect progression or regression of disease prior to anatomic imaging. Such information can be used to optimize staging, restaging, and assessment of therapy response. Functional imaging with FDG PET can also potentially help predict patient prognosis both before and after neoadjuvant therapy. FDG PET does have inherent limitations that must be acknowledged to avoid potential diagnostic pitfalls and is optimally used in combination with correlative anatomic imaging modalities such as CT and MR imaging. Nevertheless, FDG PET provides unique physiologic information that often has important clinical implications.

Benign and malignant soft-tissue tumors: posttreatment MR imaging.

Soft-tissue sarcoma requires aggressive treatment, often with a combination of radiation therapy, chemotherapy, and surgical resection. Even after multimodality treatment, local recurrence is common, and regular follow-up imaging at short intervals is required. Interpretation of posttreatment magnetic resonance (MR) images may be complicated by changes in the surgical bed or treatment field. The challenge of distinguishing posttreatment change from recurrent tumor may be minimized by using an organized, systematic approach to imaging, with emphasis on the patient's clinical and surgical history and a review of pretreatment images. Common changes that result from radiation therapy include soft-tissue trabeculation, increased fatty marrow, and focal marrow abnormalities. Rarely, radiation-induced malignancies may develop within the treatment field. Chemotherapy also influences posttreatment imaging appearance. Occasionally, it causes a substantial increase in tumor size that is a result of chemotherapy-induced hemorrhage. Although myocutaneous flaps used in reconstructive surgery may mimic a mass, they demonstrate time-dependent changes in size, signal intensity, and enhancement on MR images. Recurrent tumor is characterized by the presence of a discrete nodule or mass with signal characteristics that typically mirror those of the original tumor. MR imaging sequences such as unenhanced T1-weighted fat-suppressed and gradient-echo sequences may help differentiate posttreatment hemorrhage from local tumor recurrence. A consistent imaging approach combined with a detailed knowledge of the patient's history, familiarity with pretreatment images, and an understanding of the various posttreatment changes enables optimal monitoring of the treatment bed and maximizes accuracy in the detection of recurrence.

Imaging of soft tissue lesions of the foot and ankle.

Differential diagnosis of soft tissue lesions of the foot can be narrowed with imaging. The cystic nature of ganglia, synovial cysts, and bursitis can be confirmed with MR imaging or sonography. Location and signal characteristics of noncystic lesions can suggest Morton's neuroma, giant cell tumor of tendon sheath, and plantar fibromatosis. Synovial-based lesions of the foot and ankle can be differentiated based on presence or absence of mineralization, lesion density, signal intensity, and enhancement pattern. Knowledge of the incidence of specific neoplasms of the foot and ankle based on patient age aids in providing a limited differential diagnosis.

Postoperative imaging of the total ankle arthroplasty.

Promising results reported with currently available total ankle arthroplasty designs have led to an increased use of such devices as an alternative to ankle arthrodesis. Despite recent improvements in implant design and surgical technique, complications associated total ankle arthroplasty devices continue to be reported. Postoperative evaluation of total ankle arthroplasties relies on a combination of clinical and radiologic assessment. Familiarity with commonly used current total ankle arthroplasty devices and appropriate postoperative imaging techniques is imperative for effective characterization of the expected postoperative imaging appearances of such devices and facilitating detection of potential postoperative complications.

Postoperative evaluation of the total ankle arthroplasty.

OBJECTIVE: The purpose of this article is to review the basic design features of second-generation total ankle arthroplasty components and to illustrate the normal and abnormal postoperative imaging features associated with such devices. The usefulness of CT in postoperative evaluation will be highlighted. CONCLUSION: Postoperative evaluation of the total ankle arthroplasty necessitates a familiarity with the various designs currently in use. Radiography serves as an integral component in the postoperative evaluation of such devices, with CT offering further characterization of radiographic abnormalities.