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Biomedical subjects

L Yao

Publications and source records attributed to L Yao.

188 records · Page 11Linked to original sources
PubMedDate not supplied

Fibrous dysplasia associated with cortical bony destruction: CT and MR findings.

OBJECTIVE: Fibrous dysplasia is a benign disorder of bone that can cause cortical thinning as well as bony expansion. Full-thickness cortical bony destruction, however, typically characterizes more aggressive or malignant lesions of bone. We present three cases of fibrous dysplasia that illustrate this more aggressive and potentially confusing feature. MATERIALS AND METHODS: The findings on radiography and cross-sectional imaging studies are reviewed in three surgically proven cases of fibrous dysplasia that exhibited full-thickness cortical bony destruction. RESULTS: Well-defined cortical perforations without associated periosteal reaction were clearly seen on CT. This finding was suspected on plain radiography in only one of the three cases. A small associated soft tissue mass was detected by MR imaging in this case. Many cortical perforations were seen in the one case of polyostotic fibrous dysplasia. CONCLUSION: Full-thickness cortical bony destruction can be seen in fibrous dysplasia. This finding, which may only be evident on cross-sectional imaging studies, should not by itself alter a diagnostic impression of fibrous dysplasia supported by other radiographic and clinical features.

Adult↗
PubMedDate not supplied

MR findings in peroneal tendonopathy.

OBJECTIVE: The purpose of this presentation is to familiarize the reader with the often subtle findings of peroneal tendon derangement on MRI examination. MATERIALS AND METHODS: We present four patients who were studied with MR (1.5 T) prior to surgical exploration of the peroneal tunnel. All patients had lateral ankle symptoms for > 6 months. Normal MR anatomy and an example of the peroneus quartus tendon are also shown. RESULTS: Surgery revealed two peroneus brevis and three peroneus longus lesions. A "multipartite" appearance of the peroneus tendon on axial MR images, especially when paired with a "flame-shaped" appearance on more distal axial images, indicates a longitudinal tendon split. Both patients with peroneus brevis tendon splits had insufficient superior peroneal retinacula. CONCLUSION: Partial ruptures of the peroneal tendons characteristically take the form of longitudinal tendon splits. Axial MR images through the ankle and hindfoot can help distinguish peroneal tendonitis from longitudinal tendon splits.

Adolescent↗
PubMedDate not supplied

Preoperative sizing of meniscal allografts in meniscus transplantation.

The purpose of this study was to determine the accuracy of radiographic and magnetic resonance imaging techniques in preoperative sizing for allograft meniscus transplantation. Twelve cadaveric knee specimens underwent sequential radiographs, magnetic resonance imaging scans, and arthrotomy. Meniscus dimensions were measured in multiple planes for the purpose of determining accuracy of imaging studies in comparison with actual meniscus dimensions. Overall, magnetic resonance imaging proved only slightly more accurate than conventional radiography. The mean difference between magnetic resonance imaging measurements and actual meniscus dimensions was 2.25 +/- 2.04 mm. The mean difference between radiographic measurements and actual meniscus dimensions was 2.35 +/- 1.79 mm. Neither imaging technique was accurate for measuring individual meniscus dimensions, with only 35% of images measuring within 2 mm of actual meniscus dimensions. Using less stringent criteria for accuracy (within 5 mm), radiography and magnetic resonance imaging were 79% and 83% reliable, respectively. Failure to obtain true anteroposterior or lateral images (15 degrees of external and internal rotation) increased measurement inaccuracy. Intraobserver agreement was significantly higher for magnetic resonance imaging than for radiography. Further research into the development of alternative techniques for more reliable meniscus sizing and better understanding of the tolerance for meniscus size mismatch is necessary.

Anthropometry↗
PubMedDate not supplied

Occult intraosseous fracture: magnetic resonance appearance versus age of injury.

Twenty-two cases of occult intraosseous fracture in the region of the knee are presented. Occult intraosseous fractures have been incidentally detected in the magnetic resonance (MR) evaluation of the knee in the setting of a recent physical injury and normal radiographic studies. There is no unique mechanism of injury, but occult intraosseous fracture presumably results from direct impaction or axial overloading. MR shows speckled or band-like areas of low signal in the intramedullary space of the epiphyses, and occasionally, the adjacent metaphyses. In most cases, T2-weighted images show high signal in corresponding regions of variable size. The relative extent of high signal findings is shown to vary significantly with the age of injury. Individual variability within groups, however, precludes the actual prediction of lesion age on the basis of the MR appearance. Our observations provide indirect evidence that the findings on T2-weighted images resolve earlier than the corresponding findings on T1-weighted proton density images. The primary differential diagnosis in cases of occult intraosseous fracture is stress fracture. The diagnosis of occult intraosseous fracture may be important in explaining persistent pain after injury in otherwise normal knees.

Adolescent↗
PubMedDate not supplied

The Algase Wandering Scale: initial psychometrics of a new caregiver reporting tool.

This paper reports on the Algase wandering scale (AWS), a 28-item questionnaire, based on five dimensions of wandering. With factor analysis, an eight-factor solution explained nearly 70 percent of the variance in ratings for 151 long-term care subjects and confirmed three of the structuring dimensions. Reliability of the AWS was examined for internal consistency and for inter-rater reliability. The AWS had an alpha of .86; subscale alphas ranged between .88 (persistent walking) and .57 (routinized walking). Inter-rater reliabilities, estimated through cross-rater comparisons of the AWS and subscales with a four-point judgement of wandering status, were moderately strong and no significant differences existed between two sets of raters. Validity of the AWS and its subscales was supported by examining their ability to differentiate wanderers and nonwanderers, by positive correlation with measures of cognitive impairment and with multiple parameters of observed wandering, and by negative or no correlations with nonwandering locomotion. Although the AWS may be a useful measure of wandering in long-term care settings, validation of its factor structure and evaluation in cross-cultural samples is needed.

Aged↗
PubMedDate not supplied

Dopamine D3 receptors in rat juxtaglomerular cells.

D2-like receptors in the kidney have been suggested to be important in the regulation of renin release but the D2-like subtype(s) expressed in juxtaglomerular (JG) cells is not known. Therefore, we determined which of the D2-like family of dopamine receptors is located in primary cultures of rat juxtaglomerular (JG) cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) identified D3 and D4 but not D2Long mRNA in JG cells (n = 3). D3 receptor function was demonstrated by a concentration-dependent inhibition of forskolin-stimulated cAMP production by LY-171555 (a non-selective D2-like receptor agonist) and PD-128593 (a partially selective D3 agonist) (n = 3-7/group). The stimulatory action of LY-171555 and PD-128593 we blocked by the non-selective D2-like antagonist YM-09151. We conclude that D3 and D4 dopamine receptor subtypes are expressed in JG cells; the receptor subtype linked to the inhibition of cAMP in JG cells remains to be established.

Animals↗
PubMedDate not supplied

The evaluation of bone damage in rheumatoid arthritis with magnetic resonance imaging.

Magnetic resonance imaging (MRA) greatly improves the early detection and visualization of osseous and non-osseous joint changes over conventional x-rays of involved joints in patients with rheumatoid arthritis (RA). However, the "pathophysiological correlate" of these MR imaging changes remains poorly defined. Careful validation of MRI findings and the evaluation of MRI as a tool to follow the effect of therapy remain to be performed before MRI may be used as a clinical tool to follow therapy or as a surrogate for evaluating osseous changes over time.

Adult↗