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Abstract: This work is focused on the computation of the invariant subspace associated with a separated group of eigenvalues near a specified shift of a large sparse matrix. First, we consider the inverse subspace iteration with the preconditioned GMRES method. It guarantees a convergence to the desired invariant subspace but the rate of convergence is at best linear. We propose to use it as a preprocessing for a Newton scheme which necessitates, at each iteration, the solution of a Sylvester type equation for which an iterative algorithm based on the preconditioned GMRES method is specially devised. This combination results in a fast and reliable method. We discuss the implementation aspects and propose a theory of convergence. Numerical tests are given to illustrate our approach. [Copyright &y& Elsevier]

Objective: To date semiquantitative whole-organ scoring of knee osteoarthritis (OA) relies on 1.5 Tesla (T) Magnetic resonance imaging (MRI) systems. Less costly 1.0 T extremity systems have been introduced that offer superior patient comfort, but may have limitations concerning field-of-view and image quality. The aim of this study was to compare semi-quantitative (SQ) scoring on a 1.0 T system using 1.5 T MRI as the standard of reference.Methods: The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of individuals who have or are at high risk for knee OA. A sample of 53 knees was selected in which MRI was performed on a 1.0 T extremity system as well as on a 1.5 T scanner applying a comparable sequence protocol. MRIs were read according to the Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Agreement was determined using weighted kappa statistics. Sensitivity, specificity and accuracy were assessed using the 1.5 T readings as the reference standard. In addition the number of non-readable features was assessed.Results: Agreement (w-kappa) for seven main WORMS features (cartilage, bone marrow lesions (BMLs), osteophytes, meniscal damage and extrusion, synovitis, effusion) ranged between 0.54 (synovitis) and 0.75 (cartilage). Sensitivity ranged between 68.1% (meniscal damage) and 88.1% (effusion). Specificity ranged between 63.6% (effusion) and 96.4% (BMLs). Although the overall rate of non-readable features was very low, it was higher for the 1.0 T system (1.9% vs 0.2%).Conclusions: Semiquantitative whole organ scoring can be performed using a 1.0 T peripheral scanner with a moderate to high degree of agreement and accuracy compared to SQ assessment using a 1.5 T whole body scanner. Our results are comparable to the published inter- and intra observer exercises obtained from 1.5 T systems. Sensitivity to change of longitudinal scoring was not evaluated in this cross-sectional design and should be investigated in future validation studies. [ABSTRACT FROM AUTHOR]

This is an update on both clinical and imaging aspects of athletic injuries to the shoulder and elbow. This article focuses on injuries that are primarily seen in athletes. The lesions discussed in this update are: Bennett lesion of the shoulder, internal (posterosuperior) impingement of the shoulder, little leaguer's shoulder, little leaguer's elbow (both medial epicondylar avulsion injuries and osteochondral injuries of the capitellum) and tears of the medial ulnar collateral ligament. [ABSTRACT FROM AUTHOR]

Objectives: In regurgitant tricuspid aortic valves, cusp prolapse may be isolated or associated with dilatation of the proximal aorta. Newly appearing cusp prolapse can also appear after an aortic valve sparing operation (AVSO) and be responsible for residual aortic regurgitation. In this report, we describe our experience in repairing prolapsing aortic cusps in 44 patients with aortic regurgitation. Methods: Between 1996 and 2003, 260 patients had aortic valve repair or valve sparing procedures in our department. All patients had peri-operative TEE. Prolapse of one or more of the aortic cusps was identified by TEE and confirmed by careful surgical inspection before and after valve sparing surgery. Forty-four patients with cusp prolapse were identified. Fifteen had an isolated prolapse, with a normal root (group I), 18 had cusp prolapse associated with dilatation of the proximal aorta (group IIa), and 11 had a newly appearing prolapse after AVSO (group IIb). Correction of the prolapsing cusp was achieved by either free edge plication, triangular resection or resuspension with PTFE. This procedure was associated with an aortic annuloplasty in group I, and with AVSO in groups II and III. Results: Post-operative TEE showed AR trivial or grade I regurgitation. At a mean of 23 months follow-up, one patient with recurrent regurgitation required an aortic valve replacement with a homograft. All remaining patients were in NYHA class I or II. Echocardiography confirmed the durability of the valve repair. Conclusions: Among the common causes of aortic regurgitation, isolated cusp prolapse is frequent and is amenable to surgical repair with excellent mid-term results. In particular, in patents who are potential candidates for AVSO, identification and correction of an associated prolapse, either pre-existing or secondary to the AVSO procedure, may further extend the indications for this technique, increase its success rates and improve its long-term outcome. [Copyright &y& Elsevier]

Objective: To report five symptomatic patients, four with unequivocal Paget's disease and large areas of osteolysis and one patient with presumed osteolytic Paget's disease, evaluated by MR imaging to confirm or exclude a sarcoma.Design and Patients: Four men and one woman (median age 74 years) presented with new symptoms of pain. Four of these patients had unequivocal Paget's disease with large areas of osteolysis; one patient presented with large focal osteolysis and no other finding. MR imaging was performed in each case to exclude malignancy in the area of osteolysis.Results: Two patients whose MR images showed a low signal abnormality on the T1-weighted sequence corresponding to osteolysis on the radiograph were found to have malignant degeneration. Three patients with osteolytic lesions on T1-weighted MR imaging showed preservation of fat signal in the areas of osteolysis, were not biopsied and have been free of malignant disease for from 12 months to 2 1/2 years. One patient had one area of osteolysis in the iliac bone which showed malignancy and another area of osteolysis which showed preservation of fat signal on the T1-weighted sequence.Conclusions: The information obtained from T1-weighted MR imaging sequences performed on patients with Paget's disease who have new symptoms and large areas of osteolysis could reliably be used in the clinical decision-making process between conservative follow-up and biopsy. [ABSTRACT FROM AUTHOR]

Objective: To present and discuss six cases of calcific tendinitis in atypical locations (one at the insertion of the pectoralis major and five at the insertion of the gluteus maximus).Patients and Results: All cases were associated with cortical erosions, and five had soft tissue calcifications. The initial presentation was confusing and the patients were suspected of having infection or neoplastic disease.Conclusion: Calcific tendinitis is a self-limiting condition. It is important to recognize the imaging features of this condition to avoid unnecessary investigation and surgery. [ABSTRACT FROM AUTHOR]

Diabetic muscle infarction (DMI) is a rare complication of diabetes mellitus occurring in patients with poorly controlled insulin-dependent diabetes. In previous reports, the diagnosis of this condition was based on the pathologic studies, although MRI examinations were performed in a few patients as part of the diagnostic work-up. In this report, we describe two additional cases of DMI where the diagnosis was based on the MRI findings in conjunction with the clinical picture and laboratory studies. The patients usually present with thigh or calf pain and swelling, are afebrile, and have normal white blood cell count. MRI examination typically shows diffuse swelling and increased signal intensity on T2-weighted images in the affected muscles, with no focal fluid collections. In the proper clinical setting, these findings are diagnostic of DMI and patients should be spared unnecessary invasive diagnostic examinations such as lower extremity venograms and biopsies. [ABSTRACT FROM AUTHOR]

Objective: Percutaneous needle aspiration (PNA) has been widely used to diagnose bone malignancies. Successful aspirates hinge on the ability of the operator to obtain an adequate or diagnostic sample, and a skilled cytologist to make a diagnosis on needle aspirates. False-negative aspirates could pose a serious problem. This study is designed to evaluate the cost-effectiveness of PNA in the diagnosis of skeletal neoplasms using a cost minimization approach.Design: All PNA performed over a 44-month period were reviewed retrospectively. Ninety-four skeletal biopsies were performed to diagnose a clinically or roentgenographically suspicious lesion: 69 for a suspected metastatic malignancy, and 25 for a suspected primary malignancy. The PNA results were collected and reviewed, sensitivities and specificities were determined (compared with open biopsy results or clinical follow-up as the gold standards), and the probabilities were applied to a decision tree. Charges were obtained from the patient's billing and converted into costs by a cost-charge ratio. Sensitivity analysis was performed to determine the costs of each branch of the decision tree, and ultimately the final cost of the two strategies: (1) PNA for all suspected neoplasms followed by open biopsy for negative and non-diagnostic PNA results, or (2) open biopsy for all suspected neoplasms.Results: In diagnosing a suspected metastatic skeletal neoplasm, PNA had a sensitivity of 88%, a specificity of 100%, and a non-diagnostic result in 3% of cases. Cost analysis determined a savings of $ US 2486 per patient when "PNA strategy" was used instead of "open biopsy strategy". In diagnosing a suspected primary neoplasm, PNA hat a sensitivity 75%, a specificity of 100%, and a non-diagnostic result in 16% of cases. Cost analysis determined a savings of $ US 954 per patient when "PNA strategy" was used instead of "open biopsy strategy". By using "PNA strategy" instead of "open biopsy strategy" at this institution we would have saved $ US 195384 over the 44-month period.Conclusions: Metastatic skeletal neoplasms could be reliably diagnosed by PNA, and followed by open biopsy if the PNA result is negative or non-diagnostic, at a significant cost saving over open biopsy. Diagnosing primary skeletal neoplasms using "PNA strategy" offers a slight cost saving compared with "open biopsy strategy", but too few primary skeletal neoplasms were evaluated to recommend the best diagnostic approach. [ABSTRACT FROM AUTHOR]

The radiological diagnosis of Paget's disease of bone is usually straightforward because most cases conform to well-established classic descriptions. Diagnosis becomes more difficult, however, when radiological appearances are not typical or other disease processes mask or alter the behavior of Paget's disease. Examples are presented to illustrate four categories of unusual radiological presentation of Paget's disease: (1) unusual disease progression, (2) massive post-immobilization lysis, (3) metastatic spread to pagetic bone, and (4) vertebral end-plate destruction that mimics infection. [ABSTRACT FROM AUTHOR]

A 61-year-old man presented with a 6-month history of a painless mass in the right buttock. Although the MR appearance of myxoid neoplasms is variable, a myxoid neoplasm was suspected on the basis of the MR study. Percutaneous needle biopsy results yielded a diagnosis of intramuscular myxoma. Myxoid chondrosarcoma, however, was diagnosed at the time of excisional biopsy. One should be wary of a diagnosis of intramuscular myxoma based solely on the results of percutaneous needle biopsy. In addition, myxoid chondrosarcoma of the soft tissues can have a variable appearance on T1-weighted imaging. [ABSTRACT FROM AUTHOR]

Myxoid tissue forms part of many benign and malignant soft-tissue tumors. The advent of percutaneous needle biopsy has made it important to be aware of the diagnostic implications of biopsy samples containing myxoid tissue. To determine whether the magnetic resonance imaging (MRI) characteristics could help establish the diagnosis, we compared the MR images of 11 tumors containing myxoid tissue with the resected tumor tissue. In our small series of these rare tumors, the MRI characteristics allowed differentiation of intramuscular myxomas from malignant neoplasms containing myxoid tissue. Intramuscular myxomas meet the following conditions: (a) they are well circumscribed; (b) they arise within muscle; (c) T1-weighted images demonstrate uniform, decreased signal intensity; (d) T2-weighted images demonstrate uniform increased signal intensity; (e) contrast-enhanced images exhibit an inhomogeneous increase in signal intensity. If any of these conditions is not met, then a malignancy containing myxoid tissue should be suspected. [ABSTRACT FROM AUTHOR]

Fractures of the pisiform are often missed due to improper radiographic evaluation and a tendency to focus on other, more obvious injuries. Delayed diagnosis may result in disabling sequelae. A high index of clinical suspicion and appropriate radiographic examination will establish the correct diagnosis. Ten patients with pisiform fracture are presented. The anatomy, mechanism of injury, clinical presentation, radiographic features, and evaluation of this injury are discussed. [ABSTRACT FROM AUTHOR]

We report three patients with known primary tumor in whom radionuclide skeletal imaging for metastatic disease was normal with or without clinical symptomatology referable to this area. Magnetic resonance imaging (MRI) of the spine demonstrated focal areas of abnormal signal intensity in the vertebral bodies of these patients. In all three patients, biopsy confirmed metastatic disease. All the patients received radiation or chemotherapy depending upon the etiology. These preliminary data suggest that MR imaging may be useful in evaluating patients with known primary tumor in whom clinical suspicion persists despite a negative radionuclide bone scan. [ABSTRACT FROM AUTHOR]

Patellofemoral maltracking is a recognized cause of peripatellar pain. Measurements of the patellofemoral relationships during active motion are not available, and clinicians currently rely on observation, palpation, and static radiographic images to evaluate the symptomatic patient. Ultrafast computed tomography (ultrafast CT) offers objective observations of the dynamic influences of muscle contraction on the patellofemoral joint as the knee is actively moved through a range of motion from 90 degrees flexion to full extension. This study reports our initial observations and establishes a range of normal values so that patients with a clinical suspicion of patellar maltracking may be evaluated. [ABSTRACT FROM AUTHOR]