Weightbearing Digital Tomosynthesis of Foot and Ankle Arthritis: Comparison With Radiography and Simulated Weightbearing CT in a Prospective Study.

OBJECTIVE: Foot and ankle arthritis is common and debilitating. Weightbearing radiography is the reference standard for evaluating alignment, but overlapping bones and hardware limit evaluation for osteoarthritic bony detail. The purpose of this study was to evaluate whether digital tomosynthesis (DTS) can yield reliable quantitative alignment values, as radiography does with its weightbearing capability, and good qualitative osteoarthritic detail, as CT does. SUBJECTS AND METHODS: Adults with foot or ankle arthritis referred for simulated weightbearing CT were recruited to undergo weightbearing radiography and DTS. Four readers independently evaluated radiographs and DTS images for foot and ankle alignment and severity of osteoarthritis in each joint. Two readers performed consensus readings of CT images. Agreement between modalities was assessed by intraclass correlation coefficient (ICC) and Cohen kappa statistics. RESULTS: Ninety-one ankles were analyzed. Most joints were significantly less obscured by overlapping bone when seen with DTS (11.2%) or CT (4.3%) compared with radiography (30.4%). For quantitative foot alignment measurements, DTS had good to excellent agreement with weightbearing radiography (ICC, 0.65-0.93), which performed significantly better than CT (ICC, 0.39-0.87). For qualitative osteoarthritic details of each joint, DTS had significantly better agreement with weightbearing radiography on joint space narrowing (κ = 0.38-0.67) than did CT (κ = 0.08-0.62). Weightbearing radiography and DTS had similar levels of agreement with CT on grading of osteophytes, subchondral cysts, and loose bodies. CONCLUSION: DTS is associated with less obscuration of joints than radiography and yields more reliable weightbearing quantitative foot and ankle alignment values than radiography does and more reliable osteoarthritic bony details than CT does.

Soft Tissue Sarcoma Response to Two Cycles of Neoadjuvant Chemotherapy: A Multireader Analysis of MRI Findings and Agreement with RECIST Criteria and Change in SUVmax.

RATIONALE AND OBJECTIVES: When soft tissue sarcomas are treated with neoadjuvant chemotherapy, the number of cycles of chemotherapy is usually dependent on the tumor's initial response. Popular methods to assess tumor response include Response Evaluation Criteria in Solid Tumors (RECIST) criteria, which rely solely on tumor size, and maximum standardized uptake value (SUVmax) reduction in positron emission tomography (PET), which requires an expensive and high radiation test. We hypothesized that contrast-enhanced magnetic resonance imaging (MRI) may offer a good alternative by providing additional information beyond tumor size. MATERIALS AND METHODS: Following IRB approval, a retrospective review identified patients with soft tissue sarcomas who underwent both PET and MRI before and after two cycles of neoadjuvant chemotherapy. Five readers independently examined the MRI exams for: changes in size, T2 or T1 signal, necrosis and degree of enhancement. Readers then made a subjective binary assessment of tumor response to therapy. Each reader repeated the anonymized randomized reading at least 2 weeks apart. 18 F-FDG PET exams were interpreted by a nuclear medicine specialist. The maximum standardized uptake values (SUVmax) for pre and post-chemotherapy exams were compared. Intra- and inter-reader agreement was assessed using Cohen's kappa and Light's kappa, respectively. . RESULTS: Twenty cases were selected for this multireader study, of which 9 (45%) were responders and 11 were nonresponders by SUVmax. Using all MRI criteria, 43% were classified as responders based on MRI and 1.5% were classified as responders by RECIST criteria. Using PET as the reference, the sensitivity and the specificity of the MRI diagnosis for response using all findings were 50% and 63%, respectively. There was fair to moderate intrareader (kappa = 0.37) and inter-reader (kappa = 0.48) agreement for the MRI diagnosis of response. None of the individual MRI signal characteristics were significantly different between the PET responders and nonresponders. Additionally, no MRI findings were significantly different between those with and without good clinical responses. CONCLUSION: By our assessment, there is a poor correlation between tumor response by RECIST criteria and PET SUVmax. In addition, varying MR features did not help in diagnosing tumor response. Imaging of tumor response remains a challenging area that requires further research.

Osteoarticular transplantation: recognizing expected postsurgical appearances and complications.

Despite technologic advances in prosthetic joint replacement, young patients who have lost a large volume of bone or soft tissue because of a tumor or traumatic injury may not be good candidates for prosthetic implants, which have limited longevity relative to that of biologic tissue grafts. In recent years, the use of biologic materials in orthopedic surgery has increased. Such materials, known as allografts, consist of cadaveric bone, cartilage, and other soft tissues that can be transplanted into a living patient. Alternatively, osteochondral autografts, or autologous grafts of the patient's own bone and/or cartilage, can be harvested from one body site and transplanted to another. Surgical procedures range from the local implantation of small osteochondral plugs to the replacement of entire joints with allografts. The size of the allograft used depends on the amount of bone and soft tissue needed. The use of allografts in patients with large-volume bone loss often preserves limb function, obviating amputation, which makes it an attractive option for treatment of young patients. Advantages of using allografts include the similarity of graft materials to native tissues and the decreased patient morbidity in the absence of an autograft donor site; disadvantages include slower biologic remodeling and graft incorporation than are typical with the use of autologous grafts. Potential complications of allograft tissue implantation include graft nonunion, collapse, and failure; infection; and secondary osteoarthritis. The article discusses the indications for and basic steps involved in each type of transplant procedure, normal pre- and postoperative imaging appearances, and imaging features that may be indicative of transplant complications.