Biomedical subjects

J B Kneeland

Publications and source records attributed to J B Kneeland.

At least 19 recordsLinked to original sources

PubMed1999

A novel approach to observing articular cartilage deformation in vitro via magnetic resonance imaging.

The design of a pressure cell that compresses a cartilage specimen in one dimension within an imaging magnet is presented. One-dimensional projection images in a direction perpendicular to the articular surface of the cartilage specimen were used to generate a uniaxial confined deformation creep curve for normal and trypsin-degraded cartilage specimens during a continuous 0.690 MPa (100 psi) pressure application. The resulting curves are shown to fit a two time constant viscoelastic model well and also indicate that the elastic modulus of cartilage decreases and the deformation rate increases upon trypsin proteolysis. Furthermore, cartilage permeability is shown as a function of cartilage strain for both the normal and trypsin-degraded case. Several two-dimensional slice-selective images were collected both before and after 80 minutes of continuous compression. These images were used to evaluate the relative changes in the spin-lattice, T1, and spin-spin, T2, relaxation time constant maps for both normal and degraded cartilage specimens in response to compression. The results of this study demonstrate the utility of a novel, non-magnetic, cartilage compression device and also support the validity of a simple two-component rheological model of articular cartilage.

Animals↗

PubMed1999

MR imaging of the arthritic rabbit knee joint using albumin-(Gd-DTPA)30 with correlation to histopathology.

The purpose of this study was to demonstrate a technique, in a pilot study, for measuring abnormal capillary permeability in synovial tissue of rabbit arthritic knees using dynamic MRI with a gadolinium-based blood pool agent. Arthritis, simulating rheumatoid arthritis, was induced in knees of 8 rabbits by intra-articular injection of carrageenan (n = 4) or ovalbumin (n = 4). Sequential fat presaturated T1-weighted Spoiled Grass images were obtained before and up to 30 min after intravenous administration of albumin-(Gd-DTPA)30. Estimates of synovial tissue plasma-volume (PV), fractional-leak-rate (FLR), and permeability-surface-area-product (PS) were computed. Histologic correlation was obtained in the corresponding regions. Dynamic MRI showed extravasation of albumin-(Gd-DTPA)30 into hypertrophic synovium in six of the eight arthritic knees. Histologic examination of these six knees showed markedly inflamed synovium. The two knees that did not show abnormal vascular permeability contained non-hypertrophic synovium. None of the rabbits showed abnormal permeability in muscle. MRI derived microvascular characteristics (PV, FLR and PS) correlated positively (r2 = 0.51, 0.97 and 0.86) with the histology. Factors involving the structural and functional microvascular characteristics of synovial tissue can be estimated non-invasively using albumin-(Gd-DTPA)30. This technique may be useful for monitoring disease progression and treatment response in rheumatoid arthritis.

Albumins↗

PubMed1999

MR imaging of sports injuries of the hip.

While MR imaging studies of the hip have been directed routinely toward the diagnosis of atraumatic osteonecrosis (ON), interest has increased in the use of MR imaging to diagnose other disorders of the hip and surrounding soft tissues, especially in athletic injuries. In addition to reviewing MR imaging technical considerations and image appearance, this article discusses applications of MR imaging to diagnosing pelvic and hip fractures, muscle contusion and strain, tendon injuries, acetabular labral tears, bursitis, and osteitis pubis and chronic symphyseal injury.

Athletic Injuries↗

PubMed1998

Sodium MRI of human articular cartilage in vivo.

Preliminary results from in vivo sodium MRI of human patellar articular cartilage are presented. Sodium images generated of an in vitro bovine patella clearly distinguish the region of proteoglycan depletion from the region of healthy cartilage. This provides the first evidence that sodium imaging may be used to detect changes due to osteoarthritis in vivo. The process of optimizing imaging time and signal-to-noise ratio, as well as potential implications in the detection of osteoarthritic change, are discussed.

Animals↗

PubMed1998

Sodium multiple quantum spectroscopy of articular cartilage: effects of mechanical compression.

The effects of mechanical compression on the multiple quantum coherences generated from sodium ions in articular cartilage were investigated. Cartilage samples obtained from bovine patellae were studied during compression at 0.7 MPa (100 psi) for 1 hour. The double quantum filtered spectra showed marked lineshape changes in the compressed samples. Compression did not seem to influence the lineshapes of the single quantum and triple quantum filtered spectra significantly. We found that the residual quadrupolar interaction was reduced in the compressed samples. Changes in the ordering of collagen fibers may be responsible for the observed effect.

Animals↗

PubMed1998

A new in vivo technique for three-dimensional shoulder kinematics analysis.

OBJECTIVE: The field of shoulder kinematics research has long relied upon the use of cadaveric models or invasive techniques in human volunteers. In this paper, a novel method is presented that utilizes magnetic resonance imaging (MRI) and a software system called 3DVEWNIX. This method permits non-invasive, repetitive evaluation of living patients for glenohumeral kinematics analysis. The objectives of this study were twofold: to validate the quantitative accuracy of this technique; and to demonstrate glenohumeral relationships in asymptomatic volunteers during internal and external rotation of the arm. DESIGN: The translational accuracy was first assessed by comparing known cadaveric glenohumeral translations with calculations from MR images of the cadaver. Nine asymptomatic volunteers were subsequently placed in an external shoulder positioning device in the scanner and imaged in 10 degrees increments of actively achieved internal and external rotation. Three-dimensional reconstructions of the glenoid and humerus were used to evaluate the glenohumeral relationships in the tested positions of rotation. RESULTS: The quantitative analysis revealed an error of 0.61 mm (SEM 0.11 mm). Examination of the volunteers demonstrated normal relationships about the glenohumeral joint in internal and external rotation. In addition, this method provided detailed images of the bony surface architecture from any perspective. These images can be transformed into a cinematic three-dimensional depiction of active shoulder rotation. CONCLUSION: This new technique offers an accurate, non-invasive method for assessing the normal glenohumeral relationships in shoulder kinematics. We now possess the capability to investigate the kinematics of normal and abnormal shoulder conditions non-invasively in a large patient population.

Adult↗

PubMed1998

Analysis of in vivo 3-D internal kinematics of the joints of the foot.

This paper describes a methodology for the analysis of three-dimensional (3-D) kinematics of live joints of the foot based on tomographic image data acquired via magnetic resonance (MR) imaging. A mechanical jig facilitates acquisition of MR images corresponding to different positions of the joint in a pronation-supination motion. The surfaces of the individual tarsal bones are constructed by segmenting the MR images. A mathematical description of the motion of the individual bones and of their relative motion is derived by computing the rigid transformation required to match the centroids and the principal axes of the surfaces. The mathematically described motion is animated via surface renditions of the bones. The kinematics of the bones are analyzed based on features extracted from the motion description and on how they vary with motion. Based on 17 joints that have been imaged, which includes an abnormal joint and the same joint after surgical correction, we conclude that this methodology offers a practical tool for measuring internal 3-D kinematics of joints in vivo and for characterizing and quantifying with specificity normal kinematics and their pathological deviations. Some of the 3-D kinematic animations generated using the methods of this paper for normal joints can be seen at: http:(/)/www.mipg.upenn.edu.

Biomechanical Phenomena↗

PubMed1998

Complete atraumatic rupture of the flexor hallucis longus tendon: a case report and review of the literature.

A complete atraumatic rupture of the flexor hallucis longus tendon in a patient without systemic disease is a rare occurrence. Although four cases of complete traumatic ruptures have been cited in the literature, only one case of a complete atraumatic rupture has been previously reported. Presented here is a second case with a review of the literature and a discussion of the surgical indications.

Adult↗

PubMed1997

In vivo sodium multiple quantum spectroscopy of human articular cartilage.

The authors report, for the first time, sodium properties of human articular cartilage in vivo using sodium multiple-quantum-filtered methods with a surface coil. A flip angle-independent, phase-cycled pulse sequence was used to obtain triple-quantum-filtered spectra as a function of preparation time. Biexponential relaxation rates were calculated by fitting the triple-quantum-filtered spectral amplitudes to a theoretical expression. Theoretical analysis of the flip angle dependence of even rank two-quantum coherence (T2[2]), odd rank two-quantum coherence (T2[3]), and triple-quantum coherence are presented and verified against experimental results on a cartilage specimen. Sodium multiple-quantum-filtered spectral lineshapes obtained in vivo correlate well with those observed on in vitro specimens. Relaxation rates obtained from asymptomatic volunteers were found to be: T(2rise) = 1.0 + 0.12 ms, T(2decay) = 12.0 +/- 0.75 ms (mean +/- SD). The diagnostic potential of this method in detecting early changes in articular cartilage is described.

Animals↗

PubMed1997

T1rho-relaxation in articular cartilage: effects of enzymatic degradation.

Spin-lattice relaxation in the rotating frame (T1rho) dispersion spectroscopy and imaging were used to study normal and enzymatically degraded bovine articular cartilage. Normal specimens demonstrate significant T1rho "dispersion" (approximately 60 to approximately 130 ms) in the 100 Hz to 9 kHz frequency range. Proteoglycan-degraded specimens have 33% greater T1rho values than collagen-degraded or normal samples. T1rho-weighted images reveal structure not found in conventional T1- or T2-weighted images. Our results suggest that T1rho measurements are selectively sensitive to proteoglycan content. The potential of this method in distinguishing the early degenerative changes in cartilage associated with osteoarthritis is discussed.

Animals↗

PubMed1997

Os acromiale: evaluation of markers for identification on sagittal and coronal oblique MR images.

An os acromiale is a developmental abnormality of ossification involving the anterior acromion which may contribute to impingement and rotator cuff disease. When axial MR sections do not include the acromioclavicular joint, the diagnosis of this often subtle abnormality will rest on its recognition on oblique and coronal and sagittal images where it mimics the acromioclavicular joint. The identification of this anomaly is important as it frequently alters the type of surgical procedure utilized in symptomatic patients. We evaluate several imaging features which may be used to diagnose an os acromiale in these cases.

Acromioclavicular Joint↗

PubMed1997

Impact of CT scan on treatment plan and fracture classification of tibial plateau fractures.

OBJECTIVE: To evaluate the interobserver and intraobserver agreement for both treatment plan and fracture classification of tibial plateau fractures using plain films alone and with computed tomography (CT) scans. DESIGN: Prospective study to assess the impact of an advanced radiologic study on the agreement of treatment plan and fracture classification of tibial plateau fractures. SETTING/PARTICIPANTS: Two orthopaedic traumatologists, two orthopaedic residents, and two skeletal radiologists were presented with twenty-one cases of tibial plateau fractures imaged with plain films and with CT scans. MAIN OUTCOME MEASURES: Agreement was measured using kappa coefficients. RESULTS: Using plain films alone, the mean interobserver kappa coefficient for classification was 0.62, which decreased to 0.61 after addition of CT scans. Using plain films alone for formulating a treatment plan, the mean interobserver kappa coefficient was 0.58, which increased to 0.71 after addition of CT scans. The mean intraobserver kappa coefficient for fracture classification using plain films was 0.70, which increased to 0.80 with addition of CT scans. The mean intraobserver kappa coefficient for treatment plan based on plain films alone was 0.62, which increased to 0.82 after addition of CT scans. Class was changed in an average of 12 percent of cases after addition of CT scans. Treatment plan was changed an average of 26 percent of the time after addition of CT scans. CONCLUSION: Addition of CT scans to plain roentgenograms increases the interobserver and intraobserver agreement on treatment plan.

Algorithms↗

PubMed1997

MR imaging of the elbow. Technical considerations.

The elbow has proven the most technically challenging of all of the major joints in MR imaging, particularly with regard to radiofrequency design. It is possible to obtain high-quality diagnostic studies on most clinical MR imaging systems that are made today using available coils and pulse sequences. This article evaluates techniques for MR imaging of the elbow.

Elbow Joint↗

PubMed1996

Muscle impingement: MR imaging of a painful complication of osteochondromas.

The purpose of this study was to describe the magnetic resonance (MR) appearance of a newly recognized complication of osteochondromas. Two patients presented with pain and swelling over known osteochondromas. Plain radiographic studies were unrevealing. MR examinations were obtained to characterize the exostoses further and evaluate areas of palpable fullness. Increased signal was present in the muscles on T2-weighted images, which correlated with physical findings and was believed to represent muscle injury due to the osteochondroma. Pain and fullness may result from a number of osteochondroma-related complications, the most worrisome of which is malignant degeneration. Muscular impingement and injury should be considered in the differential diagnosis of pain and swelling in the region of an exostosis. MR imaging allows distinction of this entity, which may be radiographically occult and confused clinically with fracture, bursitis, or malignant degeneration.

Adult↗

PubMed1996

Anatomic, histologic, and magnetic resonance imaging abnormalities of the shoulder.

Six fresh frozen, human cadaver shoulders were evaluated for gross anatomic, magnetic resonance imaging, and histologic abnormalities. The shoulders underwent routine magnetic resonance imaging with and without intraarticular Gadolinium using a standard surface shoulder coil. The shoulders were dissected in a systematic fashion to yield 18 anatomic specimens from the supraspinatus and infraspinatus tendon as well as the glenoid labrum. These specimens were studied histologically using hematoxylin and eosin and Goldner's trichrome stains. Gross anatomic and magnetic resonance image abnormalities of the rotator cuff corresponded to histologic changes consistent with tendon degeneration. However, there was a poor correlation between gross anatomic, magnetic resonance image, and histologic changes of degeneration in the glenoid labrum. In general, histologic degeneration was more severe than abnormalities seen either grossly or on magnetic resonance images.

Adult↗

PubMed1996

Flexor tendon tears in the hand: use of MR imaging to diagnose degree of injury in a cadaver model.

OBJECTIVE: Treatment of flexor tendon lacerations of the finger partly depends on the degree of injury, which is difficult to determine clinically. We used a cadaver model to investigate the potential of MR imaging in evaluating these injuries. MATERIALS AND METHODS: A scalpel was drawn transversely across the volar surface of four cadaver hands, producing various flexor tendon injuries. MR imaging of each hand was performed using axial two-dimensional spin-echo and three-dimensional gradient-recalled-echo sequences. The three-dimensional data sets were interactively reformatted along the long axis of each tendon. The hands were then dissected; injury to each digit was categorized, measured, and compared with the prospective MR interpretations. RESULTS: Twelve high-grade flexor tendon tears (10 complete tears, with 1- to 14-mm separation of the torn ends, and two partial tears involving 50% or more of the total tendon cross-sectional area) and two partial tears of less than 50% of tendon area were produced; four tendons were not injured. Using MR imaging, we diagnosed 11 of the 12 high-grade lesions (those involving at least 50% of the total tendon cross-sectional area); the MR images did not show one complete tear whose separation measured 2 mm long at dissection. All intact tendons were correctly identified. We underestimated the extent of five lesions but overestimated none. Using the reformatted images, we reduced the number of errors that we would have made interpreting the transverse images alone. CONCLUSION: In this cadaver model, using MR imaging we accurately distinguished different degrees of flexor tendon tears. The potential of this technique for noninvasively diagnosing flexor tendon injury in patients awaits clinical studies.

Cadaver↗

PubMed1996

Magnetic resonance imaging in the evaluation of heel pain.

This study demonstrates magnetic resonance findings in 16 patients (25 heels) with heel pain. Sixteen of 25 (64%) studies demonstrated abnormalities which could be related to the etiology of their heel pain. Eleven of 16 abnormal scans demonstrated thickening of the plantar aponeurosis with associated fibrosis (7 of 11), and a tear of the flexor digitorum brevis (1 of 11). One study demonstrated changes in the heel pad consistent with fluid. The other four abnormal studies demonstrated changes thought to be consistent with bilateral fibrous calcaneonavicular coalitions, subtalar arthrosis and tenosynovitis of the posterior tibial, flexor digitorum longus, and flexor hallucis longus tendons.

Adult↗

PubMed1996

MRI probes biophysical structure of cartilage.

MRI of cartilage will likely remain a controversial topic for some time on account of disagreement over the appearance of normal cartilage and the accuracy of MRI for detecting early changes of osteoarthritis. This is an area, however, that may be amenable to the application of advanced imaging techniques, including magnetization transfer MRI, because of its relatively simple structure.

Arthroscopy↗