Omnidirectional displacements for deformable surfaces

Deformable surface models are often represented as triangular meshes in image segmentation applications. For a fast and easily regularized deformation onto the target object boundary, the vertices of the mesh are commonly moved along line segments (typically surface normals). However, in case of high mesh curvature, these lines may not intersect with the target boundary at all. Consequently, certain deformations cannot be achieved. We propose omnidirectional displacements for deformable surfaces (ODDS) to overcome this limitation. ODDS allow each vertex to move not only along a line segment but within the volumetric inside of a surrounding sphere, and achieve globally optimal deformations subject to local regularization constraints. However, allowing a ball-shaped instead of a linear range of motion per vertex significantly increases runtime and memory. To alleviate this drawback, we propose a hybrid approach, fastODDS, with improved runtime and reduced memory requirements. Furthermore, fastODDS can also cope with simultaneous segmentation of multiple objects. We show the theoretical benefits of ODDS with experiments on synthetic data, and evaluate ODDS and fastODDS quantitatively on clinical image data of the mandible and the hip bones. There, we assess both the global segmentation accuracy as well as local accuracy in high curvature regions, such as the tip-shaped mandibular coronoid processes and the ridge-shaped acetabular rims of the hip bones.     

Femur ultrasound (FemUS)—first clinical results on hip fracture discrimination and estimation of femoral BMD

Summary

A quantitative ultrasound (QUS) device for measurements at the proximal femur was developed and tested in vivo (Femur Ultrasound Scanner, FemUS). Hip fracture discrimination was as good as for DXA, and a high correlation with hip BMD was achieved. Our results show promise for enhanced QUS-based assessment of osteoporosis.

Introduction

Dual X-ray absorptiometry (DXA) at the femur is the best predictor of hip fractures, better than DXA measurements at other sites. Calcaneal quantitative ultrasound (QUS) can be used to estimate the general osteoporotic fracture risk, but no femoral QUS measurement has been introduced yet. We developed a QUS scanner for measurements at the femur (Femur Ultrasound Scanner, FemUS) and tested its in vivo performance.

Methods

Using the FemUS device, we obtained femoral QUS and DXA on 32 women with recent hip fractures and 30 controls. Fracture discrimination and the correlation with femur bone mineral density (BMD) were assessed.

Results

Hip fracture discrimination using the FemUS device was at least as good as with hip DXA and calcaneal QUS. Significant correlations with total hip bone mineral density were found with a correlation coefficient R ² up to 0.72 and a residual error of about one half of a T-score in BMD.

Conclusions

QUS measurements at the proximal femur are feasible and show a good performance for hip fracture discrimination. Given the promising results, this laboratory prototype should be reengineered to a clinical applicable instrument. Our results show promise for further enhancement of QUS-based assessment of osteoporosis.     

Comparison of acute rest myocardial perfusion imaging and serum markers of myocardial injury in patients with chest pain syndromes

BACKGROUND: Newer diagnostic modalities such as serum markers and acute rest myocardial perfusion imaging (MPI) have been evaluated diagnostically in patients with chest pain in the emergency department (ED), but never concurrently. We compared these two modalities in distinguishing patients in the ED with symptomatic myocardial ischemia from those with non-cardiac causes. METHODS: Serum markers and acute technetium-99m sestamibi/tetrofosmin rest MPI were obtained in 75 patients admitted to the ED with chest pain and nondiagnostic electrocardiograms. Venous samples were drawn at admission and 8 to 24 hours later for total creatine kinase, CK-MB fraction, troponin T, troponin I, and myoglobin. Three nuclear cardiologists performed blinded image interpretation. Coronary artery disease (CAD) was confirmed either by diagnostic testing or by the occurrence of myocardial infarction (MI). RESULTS: Acute rest MPI results were abnormal in all 9 patients with MI. An additional 26 patients had objective evidence of CAD confirmed by diagnostic testing. The sensitivity of acute rest MPI for objective evidence of CAD was 73%. Serum troponin T and troponin I were highly specific for acute MI but had low sensitivity at presentation. Individual serum markers had very low sensitivity for symptomatic myocardial ischemia alone. In the multivariate regression model, only acute rest MPI and diabetes were independently predictive of CAD. CONCLUSION: At the time of presentation and 8 to 24 hours later, acute rest MPI has a better sensitivity and similar specificity for patients with objective evidence of CAD when compared with serum markers.     

American society of nuclear cardiology position statement on electrocardiographic gating of myocardial perfusion SPECT scintigrams

Conclusion  In heart transplant recipients with isolated focal CAD involving the proximal or mid portion of a vessel, revascularization options exist. However, because of the increased risk of the procedure and uncertain impact on outcome, it probably is important to document evidence of provokable ischemia, especially if the patient is symptom free. Stress myocardial perfusion imaging can document ischemia related to specific coronary artery lesions and may be an important adjunct to decision making in this difficult patient population. One of the most important recent developments in single photon emission computed tomography (SPECT) myocardial perfusion imaging is the ability to acquire these studies in conjunction with electrocardiogrpahic (ECG) gating. A recommendation for incorporating ECG gating as a routine during SPECT cardiac perfusion scintigraphy is appropriate for at least four reasons: there is extensive peer-reviewed literature attesting to its value; the practice is now widespread; practitioners in diverse settings (academia dn private practive) regularly use it; and the hardware and software requirements are widely available. In addition, ASNC-sponsored continuing medical education programs for the past several years have emphasized the added information provided by ECG gating. The purpose of this position statemetn therefore is to formally encourage routine ECG gating along with SPECT myocardial perusion studies, unless technical reasons preclude this. p ]Although the principleis clear-cut, there will need to be more investigations and, ultimately, procedural guidelines to assist in optimizing acquisition and processing parametes in relation to different hardware and radiopharmaceuticals. This is a first step in a new and expanding direction for myocardial perfusion scintigraphy. Timothy M. Bateman, MD President American Society of Nuclear Cardiology     

Subarachnoid--pleural fistulae--management with a transdiaphragmatic pedicled greater omental flap: report of two cases

STUDY DESIGN: This report describes the treatment of chronic subarachnoid--pleural fistulae using a pedicled greater omentum transfer flap. OBJECTIVE: To describe a new technique for the management of chronic subarachnoid--pleural fistulae resulting from thoracic dural tears. SUMMARY OF BACKGROUND DATA: Thoracic dural tears with leakage of cerebral spinal fluid into the pleural space can occur after thoracic spine surgery. The treatment of chronic subarachnoid--pleural fistulae using an omental flap, however, has not been reported. METHODS: The clinical, radiographic, and surgical details of two cases are described. RESULTS: Pedicled greater omentum transferred to the thoracic spine was an effective method in the treatment of intractable thoracic dural tears for two patients. CONCLUSION: These cases demonstrate that pedicled greater omentum transferred to the thoracic spine can be a safe and effective technique for the management of intractable thoracic dural tears and their complications.     

The clinical significance and anatomic distribution of parathyroid double adenomas

BACKGROUND: Parathyroid double adenomas are reported to occur in 3% to 12% of cases of primary hyperparathyroidism, but the very existence of double adenomas has been controversial. This study was undertaken to evaluate the clinical significance and anatomic distribution of parathyroid double adenomas. STUDY DESIGN: The medical records of 384 consecutive patients who underwent operation for primary hyperparathyroidism were reviewed. RESULTS: A total of 27 patients (7%) were found to have double parathyroid adenomas. Intraoperative parathyroid hormone (PTH) levels were measured in each case. Two enlarged hypercellular parathyroid glands were identified in 6 possible configurations: 10 both superior, 3 both inferior, 5 both right, 3 both left, 5 right superior and left inferior, and 1 left superior and right inferior. There was preferential distribution to the bilateral superior position (p = 0.008). In all patients intraoperative PTH levels dropped by at least 50% from baseline and into the normal range after removal of both abnormal parathyroid glands. All patients remain normocalcemic 1 to 26 months postoperatively. Two patients have persistently elevated PTH values with normal serum calcium levels. CONCLUSIONS: The drop in intraoperative PTH levels and maintenance of normocalcemia postoperatively confirm previous reports that double adenomas do exist and are not simply missed cases of four-gland hyperplasia. Their incidence is more than would be expected by chance alone. The preferential occurrence of bilateral superior double adenomas suggests the possibility that these may represent hyperplasia of parathyroids arising from the fourth branchial pouch rather than isolated neoplastic events.