Search PubMed⌕ Search

Biomedical subjects

Laura M Fayad

Publications and source records attributed to Laura M Fayad.

At least 19 recordsLinked to original sources
PubMed2006

The reverse shoulder prosthesis: A review of imaging features and complications.

BACKGROUND: The reverse shoulder prosthesis is a prosthesis that has been in clinical use in Europe since 1985 and was approved for use in the United States in 2004. This unique prosthesis has a baseplate attached to the glenoid, which holds a spherical component, while the humeral component includes a polyethylene insert that is flat. This design is the "reverse" configuration of that seen with a conventional arthroplasty, in which the spherical component is part of the humeral component. The indications for the reverse prosthesis are: (1) painful arthritis associated with irreparable rotator cuff tears (cuff tear arthropathy), (2) failed hemiarthroplasty with irreparable rotator cuff tears, (3) pseudoparalysis due to massive, irreparable rotator cuff tears, (4) some reconstructions after tumor resection, and (5) some fractures of the shoulder not repairable or reconstructable with other techniques. This prosthesis can produce a significant reduction in pain and some improvement in function for most of the indications mentioned. However, the unique configuration and the challenge of its insertion can result in a high incidence of a wide variety of unusual complications. Some of these complications, such as dislocation of the components, are similar to conventional shoulder replacement. Other complications, such as notching of the scapula and acromial stress fractures, are unique to this prosthesis. CONCLUSION: The configuration of the reverse prosthesis, its normal radiographic appearance and potential complications associated with its use are reviewed.

Arthroplasty, Replacement↗
PubMed2006

Sixteen-slice CT with volumetric analysis of foot fractures.

Computed tomography (CT) imaging of the foot demands excellent resolution for the delineation of complex fractures and joint alignment after trauma. The quality of current multislice volumetric acquisition results in exceptional multiplanar and 3-D reconstructions, precluding the requirement for an additional acquisition in a second plane. This pictoral essay depicts fractures of various bones of the foot, with reference to recent investigative studies demonstrating the value of CT in the evaluation of foot fractures.

Adolescent↗
PubMed2006

Characterization of pediatric skeletal tumors and tumor-like conditions: specific cross-sectional imaging signs.

The radiograph is indispensable for characterizing pediatric skeletal lesions. However, cross-sectional imaging with CT and MRI can provide additional information and augment or confirm an impression obtained from the initial radiographic findings. This review will highlight the role of CT and MRI in characterizing pediatric skeletal tumors and tumor-like conditions. Focus will be given to the contributions of each modality to the process of characterizing skeletal lesions, recalling that cross-sectional imaging is more commonly obtained for the purpose of determining extent of disease rather than for characterization.

Anatomy, Cross-Sectional↗
PubMed2006

Vascular malformations in the extremities: emphasis on MR imaging features that guide treatment options.

Vascular malformations can be classified into high-flow arteriovenous malformations (AVM) and low-flow venous or lymphatic malformations (VM/LM). VMs and LMs have the ability to cross multiple tissue boundaries. Not only is subcutaneous tissue often involved, but multiple muscle groups, tendons, bone cortex and bone marrow are also not uncommonly violated. Magnetic resonance imaging (MRI) provides valuable information for the assessment and treatment of malformations. Firstly, MRI can characterize the flow pattern of these malformations to guide treatment towards trans-arterial embolization for AVMs and percutaneous embolization for low flow malformations. MRI is essential to define the anatomic extent and involvement of various tissue layers (a distinct advantage over ultrasound), and to correlate treatable components of the malformation with patient symptoms. Treatment is decided by the need to alleviate clinical symptoms, and is dependent on the extent of the malformation as defined by MRI. We present MRI features of vascular malformations to demonstrate the potential spectrum of involvement of these lesions, illustrating the value of MRI in treatment planning.

Arteriovenous Malformations↗
PubMed2006

Musculoskeletal tumors: use of proton MR spectroscopic imaging for characterization.

PURPOSE: To determine the value of multivoxel proton magnetic resonance spectroscopic imaging (MRSI) in distinguishing malignant skeletal tumors from benign tumors and normal bone marrow using the metabolite choline (Cho) as a marker for malignancy. MATERIALS AND METHODS: Pathologic specimens obtained from 13 patients who had undergone wide resection for skeletal tumors underwent evaluation by MRSI at 1.5 T. Coronal T1-weighted gradient-echo sequence obtained for localization purposes (TR/TE = 250/1.8 msec, field of view [FOV] = 18 x 18), and single-slice MRSI (TR/TE = 2000/272 msec, FOV = 18 x 18, 10-mm slice-thickness) were performed. Water, lipid, and Cho images were reconstructed from MRSI data. Cho signal was measured in each specimen and expressed relative to background noise level (signal-to-noise ratio [SNR]) where noise was measured between 7.0 and 9.0 ppm. Cho SNRs were compared between areas containing malignant tumor and nonmalignant tissue (benign lesion or normal bone marrow) as determined by histopathology. RESULTS: Specimens included 13 skeletal sarcomas (seven osteosarcomas, three chondrosarcomas, one malignant fibrous histiocytoma, one fibrosarcoma, and one leiomyosarcoma). All specimens included a sample of normal bone marrow and two specimens also contained benign lesions. All sarcomas demonstrated a signal at 3.2 ppm assigned to Cho-containing metabolites in areas of malignancy. Peak Cho SNR was significantly different for areas containing histologically-proven malignancy compared to nonmalignant tissue (9.8 +/- 5.1 vs. 2.7 +/- 1.4, respectively, P < 0.002). CONCLUSION: These preliminary results indicate that MRSI at 1.5 T is a promising noninvasive method of differentiating malignant skeletal tumors from nonmalignant tissue. Using MRSI, Cho can be detected in skeletal tumors and may serve as a marker for malignancy.

Bone Neoplasms↗
PubMed2005

Distinguishing stress fractures from pathologic fractures: a multimodality approach.

Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount.

Algorithms↗
PubMed2005

Image overlay guidance for needle insertion in CT scanner.

We present an image overlay system to aid needle insertion procedures in computed tomography (CT) scanners. The device consists of a display and a semitransparent mirror that is mounted on the gantry. Looking at the patient through the mirror, the CT image appears to be floating inside the patient with correct size and position, thereby providing the physician with two-dimensional (2-D) "X-ray vision" to guide needle insertions. The physician inserts the needle following the optimal path identified in the CT image rendered on the display and, thus, reflected in the mirror. The system promises to reduce X-ray dose, patient discomfort, and procedure time by significantly reducing faulty insertion attempts. It may also increase needle placement accuracy. We report the design and implementation of the image overlay system followed by the results of phantom and cadaver experiments in several clinical applications.

Biopsy↗
PubMed2005

Distinction of long bone stress fractures from pathologic fractures on cross-sectional imaging: how successful are we?

OBJECTIVE: The objectives of our study were to define CT and MRI features that distinguish pathologic fractures from stress fractures and to compare the performance of CT and MRI with radiography. MATERIALS AND METHODS: Two reviewers retrospectively reviewed 45 MR images, 37 CT scans, and 43 radiographs in 59 patients (30 biopsy-proven pathologic fractures and 29 stress fractures followed to resolution). The features observed on MRI were abnormal bone marrow (well-defined, ill-defined); intracortical, periosteal, or muscle T1 or T2 signal; endosteal scalloping; and a soft-tissue mass. The features seen on CT were marrow abnormality and character (well-defined, ill-defined, permeative, moth-eaten), endosteal scalloping, periosteal reaction (benign, aggressive), and a soft-tissue mass. Reviewers rated their confidence for diagnosing a pathologic fracture on a 1-3 scale (< 50%, 50-95%, > 95% sure, respectively) with each technique. Performance of each technique was defined by reviewer accuracy and area under the receiver operating characteristic curve (Az); the frequency with which the MRI and CT features were associated with pathologic and stress fractures was calculated. RESULTS: For both reviewers, accuracy for differentiating pathologic from stress fractures was highest on MRI (accuracy/Az: reviewer 1, 98%/0.97; reviewer 2, 93%/0.99); CT (reviewer 1, 88%/0.83; reviewer 2, 82%/0.90) was less accurate than radiography (reviewer 1, 94%/0.98; reviewer 2, 88%/0.96). On MRI, pathologic fractures compared with stress fractures exhibited well-defined T1 marrow signal (83% vs 7%, respectively; p < 0.001), endosteal scalloping (58% vs 0%, p < 0.001), muscle signal (83% vs 48%, p = 0.026), and a soft-tissue mass (67% vs 0%, p < 0.001). On CT, pathologic fractures compared with stress fractures exhibited marrow abnormality (84% vs 17%, respectively; p = 0.001), endosteal scalloping (44% vs 0%, p = 0.006), and aggressive periosteal reaction (36% vs 0%, p = 0.04). CONCLUSION: MRI is useful for distinguishing pathologic from stress fractures, especially after inconclusive radiographic findings. Specifically, pathologic fractures exhibit well-defined T1 marrow alterations, endosteal scalloping, and adjacent soft-tissue abnormalities.

Adolescent↗
PubMed2005

Functional MR cholangiography: diagnosis of functional abnormalities of the gallbladder and biliary tree.

OBJECTIVE: Our objective was to describe the technique and utility of functional MR cholangiography (fMRC) in the evaluation of the gallbladder and biliary tree. CONCLUSION: FMRC has the potential to provide a comprehensive examination for the anatomic and functional assessment of the gallbladder and biliary tree. Complex anatomic abnormalities and functional disorders can be shown by fMRC, including biliary obstruction and extravasation.

Biliary Tract↗
PubMed2005

Image overlay for CT-guided needle insertions.

OBJECTIVE: We present a 2D image overlay device to assist needle placement on computed tomography (CT) scanners. MATERIALS AND METHODS: The system consists of a flat display and a semitransparent mirror mounted on the gantry. When the physician looks at the patient through the mirror, the CT image appears to be floating inside the body with correct size and position as if the physician had 2D 'X-ray vision'. The physician draws the optimal path on the CT image. The composite image is rendered on the display and thus reflected in the mirror. The reflected image is used to guide the physician in the procedure. In this article, we describe the design and various embodiments of the 2D image overlay system, followed by the results of phantom and cadaver experiments in multiple clinical applications. RESULTS: Multiple skeletal targets were successfully accessed with one insertion attempt. Generally, successful access was recorded on liver targets when a clear path opened, but the number of attempts and accuracy showed variability because of occasional lack of access. Soft tissue deformation further reduced the accuracy and consistency in comparison to skeletal targets. CONCLUSION: The system demonstrated strong potential for reducing faulty needle insertion attempts, thereby reducing X-ray dose and patient discomfort.

Animals↗
PubMed2003

MR imaging of anterior cruciate ligament tears: is there a gender gap?

OBJECTIVE: Clinically, females receive anterior cruciate ligament (ACL) tears more commonly than males. We explored whether gender differences exist in MR imaging patterns of ACL tears. DESIGN AND PATIENTS: At 1.5 T, two observers evaluated MR examinations of 84 consecutive age-matched patients (42 males, 42 females, aged 16-39) with ACL tears, for mechanism of injury, extent and type of tear, the presence of secondary signs and associated osseous, meniscal and ligamentous injuries. RESULTS: The most common mechanism of injury for both females and males was the pivot shift mechanism (67 and 60%, respectively). Females were more commonly imaged in the acute stage of tear than males (98 and 67%, respectively, p=0.001) and more commonly possessed the typical posterolateral tibial bone contusion pattern (88 and 62%, respectively, p=0.0131). Males exhibited a deeper femoral notch sign (2.7 and 2.0 mm, p=0.007) and medial meniscal, lateral collateral ligament and posterior cruciate ligament injuries more commonly than females (48 and 24%, p=0.009, 30 and 7%, p=0.035, 17 and 0%, p=0.035). There was no significant difference between genders for the presence of other secondary signs and contusion patterns, associated lateral meniscal tears, presence of O'Donoghue's triad or associated medial collateral ligament injuries. CONCLUSION: Gender differences in MR imaging patterns of ACL tears exist: females are more commonly imaged in the acute stage and more commonly possess posterolateral tibial bone contusions; males have a more severe presentation than females, associated with more severe lateral femoral condyle and soft tissue injuries.

Acute Disease↗
PubMed2003

Functional magnetic resonance cholangiography (fMRC) of the gallbladder and biliary tree with contrast-enhanced magnetic resonance cholangiography.

PURPOSE: To determine the diagnostic performance of functional magnetic resonance cholangiography (fMRC) for the evaluation of anatomic and functional biliary disorders. MATERIALS AND METHODS: At 1.5 T, 39 MR examinations with conventional MRC and mangafodipir trisodium-enhanced fMRC were retrospectively reviewed by three observers who recorded anatomic (duct dilation, stricture, filling defects) and functional (cholecystitis, obstruction) abnormalities in three modes: MRC alone, fMRC alone, and MRC and fMRC images together (combined-MRC). Performance was determined by comparing findings with each mode to findings of invasive cholangiography (IC) and surgery. RESULTS: Among 75 biliary segments (correlated with IC), the sensitivity/specificity for diagnosing dilation (N = 41) with MRC was 95%/97%; with fMRC, 90%/100%; with combined-MRC, 100%/97%. For stricture (N = 7), the sensitivity/specificity of MRC was 86%/98%; of fMRC, 43%/100%; of combined-MRC, 86%/100%. For filling defects (N = 9), the sensitivity/specificity of MRC was 91%/98%; of fMRC, 82%/100%; of combined-MRC, 91%/100%. For diagnosing obstruction (N = 9), the sensitivity/specificity of MRC, fMRC, and combined-MRC were 89%/100%, 100%/100%, and 100%/100%, respectively. For surgically proven cholecystitis (N = 13), positive predictive values for diagnosing acute/chronic cholecystitis for MRC were 33%/40%; for fMRC, 100%/50%; for combined-MRC, 100%/50%. CONCLUSION: Although single-shot fast spin echo (SSFSE)-MRC is valuable, the addition of fMRC increased diagnostic performance for functional biliary disorders.

Biliary Tract↗
PubMed2003

MR cholangiopancreatography: evaluation of common pancreatic diseases.

In the evaluation of common pancreatic diseases, MRCP is a noninvasive alternative to ERCP. Ductal anatomy can be ascertained without risk of complications. MRCP is valuable in defining common anatomic variants, determining the state of the pancreatic duct in pancreatitis, and characterizing neoplasms, especially combined with other MR imaging sequences. With the advent of MRCP, techniques requiring endoscopy and percutaneous access are largely reserved for histologic diagnosis and treatment, or for cases in which MRCP fails to establish a diagnosis.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2003

Sacral fractures: a potential pitfall of FDG positron emission tomography.

OBJECTIVE: Positron emission tomography (PET) with FDG is useful for tumor imaging, but false-positive results can occur. The purpose of this study is to describe three oncology patients with sacral fractures in whom FDG uptake in the sacrum increased on PET. CONCLUSION: Sacral fractures can show increased uptake of FDG on PET. Therefore, correlative cross-sectional imaging is necessary to avoid the erroneous diagnosis of sacral metastases on PET and prevent inappropriate treatment of patients.

Aged↗
PubMed2002

Chest CT window settings with multiscale adaptive histogram equalization: pilot study.

Multiscale adaptive histogram equalization (MAHE), a wavelet-based algorithm, was investigated as a method of automatic simultaneous display of the full dynamic contrast range of a computed tomographic image. Interpretation times were significantly lower for MAHE-enhanced images compared with those for conventionally displayed images. Diagnostic accuracy, however, was insufficient in this pilot study to allow recommendation of MAHE as a replacement for conventional window display.

Algorithms↗