Bootstrap methods for sex determination from the os coxae using the ID3 algorithm.

This study presents a method for identifying small subsets of morphological attributes of the skeletal pelvis that have consistently high reliability in assigning the sex of unknown individuals. An inductive computer algorithm (ID3) was applied to a bootstrapped training set/test set design in which the model was developed from 70% of the sample and tested on the remaining 30%. Relative accuracy of sex classification was evaluated for seven subsets of 31 morphological features of the adult os coxae. Using 115 ossa coxarum selected from the Terry Collection, a selected suite of the three most consistently diagnostic attributes averaged 93.1% correct classification of individuals by sex over ten trials. Attribute suites developed collaboratively with three well known skeletal experts averaged 87.8, 91.3, and 89.6% correct. The full set of 31 attributes averaged 90.0% accuracy. We demonstrate a small set of three criteria, selected and ordered by ID3, that is more accurate than other combinations, and suggest that ID3 is a useful approach for developing identification systems.

Prevalence changes in modifiable cardiovascular disease risk factors in three Missouri regions, 1990-1996.

OBJECTIVES: To determine the prevalence and prevalence trend of modifiable cardiovascular disease (CVD) risk factors among African Americans and whites/others from 1990-1996. We also examined differential changes between African Americans and whites/others during the same time period. METHODS: This study used data from two special Behavioral Risk Factor Surveillance System (BRFSS) based surveys in 1990 (N = 3,000+) and one in 1996 (N = 2,095) that targeted two metropolitan and one rural region in Missouri with substantial minority populations. Risk factors included physical inactivity, obesity, hypertension, unmonitored cholesterol and smoking. The percent change in prevalence estimates and corresponding confidence intervals between survey years were calculated for each of the above risk factors. RESULTS: When compared with Missouri BRFSS data, overall prevalence of smoking, obesity, hypertension and unmonitored cholesterol was higher in the three-region study population than the state as a whole. African-American males did not experience any statistically significant reductions in CVD risk factor prevalence rates between 1990 and 1996, while the increase in obesity was driven mostly by the African-American female subgroup. The least amount of reduction in CVD risk factors was seen in individuals aged 55 or older, with a high school education or less and/or without health insurance. CONCLUSIONS: Individuals of African-American ethnicity, aged 55 or older, with a high school education or less and/or without health insurance need to be the focus of future public health initiatives designed to reduce the prevalence of CVD risk factors.

Transsynaptic reduction in N-acetyl-aspartate in cerebellar diaschisis: a proton MR spectroscopic imaging study.

OBJECTIVE: To determine if the transneuronal cerebellar hemispheric metabolic asymmetry seen in crossed cerebellar diaschisis, and readily detected with positron emission tomography (PET), is associated with alterations in metabolite signal intensities on [1H]MR spectroscopic (MRS) imaging when compared with the normal pattern and distribution of cerebellar metabolites. MATERIALS AND METHODS: The pattern and distribution of metabolites [N-acetyl-aspartate (NAA), choline-containing compounds, creatine, phosphocreatine, and lactate] in the cerebellum, using [1H]MRS imaging, were studied in a patient with documented long-standing (3 years duration) crossed cerebellar diaschisis and seven normal subjects. Cerebellar diaschisis was detected with fluorodeoxyglucose-PET imaging. Single slice [1H]MRS imaging was carried out at 1.5 T. RESULTS: There was a marked reduction in NAA signal intensity in the diaschitic cerebellar hemisphere but minimal reduction in choline and creatine signal intensities. The decrease in NAA signal intensity was most marked in the middle cerebellar peduncle and white matter of the diaschitic cerebellar hemisphere. In the normal subjects and in the uninvolved cerebellar hemisphere of the patient the NAA signal intensity was more prominent in the white matter than the cerebellar cortex. CONCLUSION: Our data indicate (a) transneuronal metabolic effects can be detected with [1H]MRS imaging and (b) there is a differential distribution of metabolite signal intensities in the cerebellum with NAA signal intensity predominantly localized to axons of the cerebellar fiber tracts rather than neuronal cell bodies in the cortex and the converse is true for choline and creatinine signal intensities.

MR imaging of knee hyaline cartilage: evaluation of two- and three-dimensional sequences.

Magnetic resonance (MR) imaging of cadaveric knees was performed to determine optimal sequences for visualization of hyaline cartilage. Full-thickness cartilage lesions ranging in diameter from 1 to 5 mm and a partial-thickness cartilage lesion 15 mm in diameter were created in the femoral articular surfaces of three cadaveric knees. The knees were then imaged with a 1.5-T imager with various two-dimensional and high-resolution three-dimensional (3D) techniques. After imaging, the knee specimens were sectioned for evaluation. Measurements of cartilage thickness in fast spin-echo images correlated best with those in the gross specimen. Diffuse areas of cartilage thinning were also most accurately identified with fast spin-echo images. Small, focal cartilage defects were best delineated in 3D SPGR (spoiled GRASS [gradient-recalled acquisition in the steady state]) images.

Mapping of brain tumor metabolites with proton MR spectroscopic imaging: clinical relevance.

Brain tumor metabolism was studied with hydrogen-1 magnetic resonance spectroscopy and positron emission tomography with fluorine-18 fluorodeoxyglucose in 50 patients. N-acetylaspartate (NAA) was generally decreased in tumors and radiation necrosis but was somewhat preserved at neoplasm margins. Choline was increased in most solid tumors. Solid high-grade gliomas had higher normalized choline values than did solid low-grade gliomas (P < .02), but the normalized choline value was not a discriminator of tumor grade, since necrotic high-grade lesions had reduced choline values. Serial studies in one case showed an increase in choline as the glioma underwent malignant degeneration. Choline values were lower in chronic radiation necrosis than in solid anaplastic tumors (P < .001). In two cases studied before and after treatment, clinical improvement and a reduction in choline followed therapy. Lactate is more likely to be found in high-grade gliomas, but its presence is not a reliable indicator of malignancy.

Pelvic imaging with phased-array coils: quantitative assessment of signal-to-noise ratio improvement.

The signal-to-noise ratios (S/Ns) of two different pelvic magnetic resonance (MR) imaging phased arrays were compared with that of the body coil. Each array consisted of two coils placed anteriorly and two posteriorly, oriented transversely in one array and longitudinally in the other. S/N measurements were obtained in an adjustable water-filled phantom that stimulated the shape and radio-frequency loading effects of various-size patients. Depending on the simulated anterior-posterior thickness of the patient, the S/N produced by the longitudinal array ranged from 2.3 to 3.1 times higher than that of the body coil. The S/N of the transverse array was 3.1 to 3.4 times higher. The increased coil sensitivity permits imaging with shorter acquisition times, smaller fields of view, finer resolution, and/or thinner sections. Two examples in patients demonstrate the enhanced imaging capability of the phased arrays.

Diffuse "fibrillary" astrocytomas: correlation of MRI features with histopathologic parameters and tumor grade.

MR images in 54 patients with biopsy-proven diffuse or "fibrillary" astrocytomas were analyzed and compared with the histopathologic features in order to determine which histopathologic characteristics underlie the radiographic findings in these gliomas and whether radiographic findings are more closely correlated with individual histopathologic characteristics than with histologically determined tumor grade. The MRI features studies included tumor heterogeneity, edema, mass effect, border sharpness, "anatomic invasion", contrast enhancement, hemorrhage, and the presence of flow voids, calcium and cyst formation. The histopathologic characteristics studied included cellular atypia, mitoses, cellularity, endothelial proliferation, necrosis and tumor grade. Edema (P less than 0.01), flow voids (P = 0.02) and contrast enhancement (P less than 0.01) demonstrated a direct correlation with tumor grade, but edema (P less than 0.01) and contrast enhancement (P less than 0.01) also demonstrated a significant correlation to tumor cellularity. Tumor heterogeneity was associated with the presence of necrosis (P = 0.01). Hemorrhage occurred only in high grade tumors, where it correlated with endothelial proliferation (P = 0.04).

MR appearance of painful conditions of the ankle.

Magnetic resonance (MR) imaging was performed in 60 patients with ankle pain who were suspected of having various soft-tissue or osseous abnormalities. Results of conventional radiographs had been normal or inconclusive. Soft-tissue disorders depicted by MR imaging included tendon and ligament tears, tendinitis, tenosynovitis, and plantar fasciitis. Osseous conditions demonstrated by MR imaging included osteochondritis dessicans, infarcts, bone bruises, stress fractures, tarsal coalition, and osteoid osteoma. The authors believe that MR imaging is useful in the assessment of a variety of painful ankle disorders.

MR imaging of the normal ligaments and tendons of the ankle.

The 10 major ligaments and nine major tendons of the ankle were evaluated in 17 ankle MR studies to determine the incidence of visualization of each structure in each of the three orthogonal planes. High-resolution technique was used, with 3 mm slice thickness and an in-plane resolution of 0.6 mm. Of the 19 ligaments and tendons evaluated, 18 demonstrated more than 70% frequency of visualization in at least one imaging plane. However, seven ligaments and three tendons demonstrated 0% visualization in at least one of the three orthogonal planes. Seven ligaments showed more than 70% visualization in only one plane (three coronal, two axial, two sagittal). Only the Achilles tendon and anterior tibial tendon demonstrated 100% visualization in all three planes. We conclude that all three orthogonal planes are essential to achieve optimal visualization of all of the major ligaments and tendons of the ankle. For specific evaluation of selected ligaments or tendons, only one or two planes may be required.

Technical variables influencing the detection of acute deep vein thrombosis by magnetic resonance imaging.

To establish which technical variables influence the detection of deep vein thrombosis by magnetic resonance imaging, 2 dogs, 5 normal volunteers and 17 patients were studied using a 1.5 T whole-body system. A sequential slice gradient echo acquisition (TR 25, TE 13, 0 = 30 degrees, 2 NEX, flow compensation rephasing gradients) in the axial plane was found to be optimal for detecting venous thrombosis. Thus, when using appropriate technique, MRI may identify deep venous thrombosis accurately. It may also allow the diagnosis of conditions which may simulate venous thrombosis clinically since the most common of these, ruptured Baker's cyst, cellulitis, muscle tear, hematoma and external venous compression are all readily identified by MRI.

Cerebrospinal fluid rhinorrhea: depiction with MR cisternography in dogs.

Canine cerebrospinal fluid rhinorrhea, which occurs frequently in purebred beagles, was demonstrated in two dogs on magnetic resonance images after cisternal introduction of gadolinium-DTPA dimeglumine.

Changes in cerebral ventricular dimensions related to the cardiac cycle as seen with gated magnetic resonance imaging.

The dynamic changes in ventricular dimensions related to the cardiac cycle were evaluated by analyzing gated magnetic resonance images in normal volunteers and in several patients with ventriculomegaly. Small variations in dimensions of the lateral and third ventricles were observed shortly after cardiac systole.