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Biomedical subjects

R G Henry

Publications and source records attributed to R G Henry.

At least 19 recordsLinked to original sources
PubMed2001

Menstrual cycle variation of apparent diffusion coefficients measured in the normal breast using MRI.

Recent investigations have shown that tumors may be distinguished from benign lesions in the breast based on differences in apparent diffusion coefficient (ADC) values. The goal of this study was to assess the magnitude of normal variations in the measured ADC of breast parenchyma during the menstrual cycle. Eight healthy female subjects were scanned once a week for 4 weeks, using a diffusion-weighted single-shot fast spin-echo (DW-SSFSE) sequence. The ADC of breast fibroglandular tissue was calculated for each woman at each time point. Results showed a trend of decreased ADC during the second week of the cycle, and increased ADC during the final week. However, no significant influence of menstrual cycle on breast ADC values was identified. The results of this study show that the normal fluctuation of breast ADC is relatively small, and the coefficient of variation was determined to be 5.5% for our group of volunteers during a menstrual cycle. Nonetheless, breast diffusion measurements for tumor differentiation and evaluation of treatment response should be interpreted with consideration of normal variability.

Adult↗
PubMed2001

The role of isotropic diffusion MRI in children under 2 years of age.

Our objective was to determine the contribution of diffusion MR imaging to standard MR imaging in the neuroradiological evaluation of children less than 2 years of age. Echo-planar diffusion MR imaging was added to standard MR exams in 75 consecutive patients under the age of 2 years. Single-shot echo-planar spin-echo T2 weighted images (EPSE-T2) were acquired. Isotropic diffusion-weighted images (DWI), attenuation coefficient maps (ACM), and apparent diffusion co-efficient (ADC) maps were calculated offline from images obtained with diffusion gradients (b = 1000 s/mm2) in three orthogonal directions. Two neuroradiologists determined if EPSE-T2, DWI, or ACM contributed new information to spin-echo proton density (SE PD) and T2 studies. In 15 of 18 abnormalities detected in 8 patients with symptoms less than 1 week in duration, DWI and/or ACM added information to SE PD and T2. Diffusion sequences detected five new lesions, showed six lesions with greater conspicuity, and identified four lesions with different diffusion character. In patients with symptoms of more than 7 days duration, diffusion studies added no information. Isotropic diffusion MR contributed to lesion detection and characterization in infants when symptoms were less than 1 week in duration. Diffusion MR is useful in patients with leukodystrophies, metabolic disorders, and patients with acute ischemic lesions.

Adult↗
PubMed2001

Preoperative proton MR spectroscopic imaging of brain tumors: correlation with histopathologic analysis of resection specimens.

BACKGROUND AND PURPOSE: Tumor progression is often difficult to distinguish from nonneoplastic treatment response on the basis of MR images alone. This study correlates metabolite levels measured by preoperative MR spectroscopic (MRS) imaging with histologic findings of biopsies, obtained during image-guided resections of brain mass lesions, to clarify the potential role of MRS in making this distinction. METHODS: Twenty-nine patients with brain tumors underwent high-resolution (0.2-1 cc) 3D proton MRS imaging and MR imaging before undergoing surgery; 11 had a newly diagnosed neoplasm, and 18 had recurrent disease. Surgical biopsies were obtained from locations referenced on MR images by guidance with a surgical navigation system. MR spectral voxels were retrospectively centered on each of 79 biopsy locations, and metabolite levels were correlated with histologic examination of each specimen. RESULTS: All mass lesions studied, whether attributable to tumor or noncancerous effects of previous therapy, showed abnormal MR spectra compared with normal parenchyma. When the pattern of MRS metabolites consisted of abnormally increased choline and decreased N-acetyl aspartate (NAA) resonances, histologic findings of the biopsy specimen invariably was positive for tumor. When choline and NAA resonances were below the normal range, histologic findings were variable, ranging from radiation necrosis, astrogliosis, and macrophage infiltration to mixed tissues that contained some low-, intermediate-, and high-grade tumor. CONCLUSION: This study demonstrated that 3D MRS imaging can identify regions of viable cancer, which may be valuable for guiding surgical biopsies and focal therapy. Regions manifesting abnormal MR spectra had a mixture of histologic findings, including astrogliosis, necrosis, and neoplasm.

Adolescent↗
PubMed2001

Three-dimensional proton MR spectroscopic imaging of premature and term neonates.

BACKGROUND AND PURPOSE: Previous studies have primarily used single-voxel techniques to obtain MR spectra from the neonatal brain. In this study, we applied 3D MR spectroscopic imaging techniques to detect the spatial distribution of MR spectroscopic imaging-detectable compounds in premature and term infants. The goals were to test the feasibility of obtaining 3D MR spectroscopic images of newborns, assess the spatial variations of metabolite levels, and determine age-dependent differences in MR spectroscopic imaging data. METHODS: MR spectroscopic imaging data were acquired from nine premature (postconceptional age, 30-34 weeks) and eight term (postconceptional age, 38-42 weeks) neonates, all with normal clinical and neurologic outcomes. A specialized point-resolved spectroscopy sequence with very selective saturation pulses was used to select a region encompassing the majority of the brain. Phase encoding in three dimensions was performed in a 17-minute acquisition time to obtain 3D spectral arrays with a 1.0 cm(3) nominal spatial resolution. RESULTS: This study showed the feasibility of detecting the 3D distributions of choline, creatine, and N-acetylaspartate resonances in the neonatal brain. Significant spectral differences were detected among anatomic locations and between the premature and term groups. CONCLUSION: This initial study indicates that 3D MR spectroscopic imaging of the neonatal brain can detect anatomic and age-dependent variations in metabolite levels. This technique seems to be a powerful tool to assess the metabolic differences between anatomic regions and to follow the changes in cellular metabolites with brain maturation. This study also indicates the need for determining topologic and age-matched normative values before metabolic abnormalities in neonates can be accurately assessed by MR spectroscopy.

Aspartic Acid↗
PubMed2000

Comparison of relative cerebral blood volume and proton spectroscopy in patients with treated gliomas.

BACKGROUND AND PURPOSE: Elevated relative regional cerebral blood volume (rCBV) reflects the increased microvascularity that is associated with brain tumors. The purpose of this study was to investigate the potential role of rCBV in the determination of recurrent/residual disease in patients with treated gliomas. METHODS: Thirty-one rCBV studies were performed in 19 patients with treated gliomas. All patients also had proton MR spectroscopy and conventional MR imaging. Regions of abnormality were identified on conventional MR images by two neuroradiologists and compared with rCBV and MR spectroscopic data. Metabolites and rCBV were quantified and compared in abnormal regions. RESULTS: In high-grade tumors, rCBV values were proportional to choline in regions of tumor and nonviable tissue. Although the presence of residual/recurrent disease was often ambiguous on conventional MR images, the rCBV maps indicated regions of elevated vascularity in all low-grade tumors and in 12 of 17 grade IV lesions. Regions of elevated and low rCBV corresponded well with spectra, indicating tumor and nonviable tissue, respectively. CONCLUSION: This study suggests that rCBV maps and MR spectroscopy are complementary techniques that may improve the detection of residual/recurrent tumor in patients with treated gliomas. Compared with the spectra, the rCBV maps may better reflect the heterogeneity of the tumor regions because of their higher resolution. The multiple markers of MR spectroscopy enable better discrimination between normal and abnormal tissue than do the rCBV maps.

Adult↗
PubMed1999

High spatial resolution 1H-MRSI and segmented MRI of cortical gray matter and subcortical white matter in three regions of the human brain.

High-resolution MR imaging and spectroscopic imaging were used to study differences in proton spectra between cortical gray matter and subcortical white matter in 23 normal volunteers using a 1.5 T scanner and surface coil receivers. A point-resolved spectroscopy (PRESS) volume with an 8 x 8 x 8 phase-encoding matrix was used to acquire over 1900 0.09-0.2 cc spectral voxels. The high-resolution (0.7 x 0.7 x 0.8 mm3 or 0.8 x 0.8 x 1 mm3) images were corrected for the surface coil reception profile and segmented into cerebrospinal fluid (CSF) and gray and white matter to correlate with the spectra. The data showed that N-acetyl aspartate (NAA) and creatine (Cr) were higher in the gray matter than in the white matter (NAA(g/w) = 1.4+/-0.36, Cr(g/w) = 1.4+/-0.41). Choline was significantly lower in the gray matter of the occipital lobe than in the white matter (0.73+/-0.19), but not significantly different in the other regions. NAA/Cho was found to be significantly higher in the occipital lobe than in the left frontal or vertex regions.

Adult↗
PubMed1999

Alzheimer's disease, dental amalgam and mercury.

BACKGROUND: Mercury, or Hg, is a neurotoxin that has been speculated to play a role in the pathogenesis of Alzheimer's disease, or AD. Dental amalgam releases low levels of Hg vapor and is a potential source of Hg for a large segment of the adult population. METHODS: The authors studied 68 subjects with AD and 33 control subjects without AD to determine Hg levels in multiple brain regions at autopsy and to ascertain the subjects' dental amalgam status and history. The subjects were from central Kentucky and Elm Grove, Wis. The authors conducted dental amalgam assessments during the lives of the majority of subjects and in some subjects at the time of autopsy only. The authors also determined three dental amalgam index scores--Event (placement, repair or removal of amalgam), Location and Time In Mouth--in addition to the numbers of and surface area of occlusal amalgam restorations. The authors determined Hg levels in multiple brain regions and performed full neuropathologic evaluations to confirm the normal status of the brain or the presence of AD. RESULTS: The authors found no significant association of AD with the number, surface area or history of having dental amalgam restorations. They also found no statistically significant differences in brain Hg level between subjects with AD and control subjects. CONCLUSIONS: Hg in dental amalgam restorations does not appear to be a neurotoxic factor in the pathogenesis of AD. The authors found that brain Hg levels are not associated with dental amalgam, either from existing amalgam restorations or according to subjects' dental amalgam restoration history. CLINICAL IMPLICATIONS: Dental amalgam restorations, regardless of number, occlusal surface area or time, do not relate to brain Hg levels.

Adult↗
PubMed1999

Alzheimer's disease and cognitively impaired elderly: providing dental care.

With the number of adults reaching older ages, the number of Americans who develop Alzheimer's disease and other neurological impairments will also increase. The dental management of these patients requires a great deal of understanding and patience coupled with background knowledge of the disease and proficiency in providing behavior modification techniques. This paper discusses five major areas that dental practitioners should consider prior to caring for patients with Alzheimer's disease or other neurological impairments.

Aged↗
PubMed1997

Serial proton magnetic resonance spectroscopy imaging of glioblastoma multiforme after brachytherapy.

The utility of three-dimensional (3-D) proton magnetic resonance spectroscopy (1H-MRS) imaging for detecting metabolic changes after brain tumor therapy was assessed in a serial study of 58 total examinations of 12 patients with glioblastoma multiforme (GBM) who received brachytherapy. Individual proton spectra from the 3-D array of spectra encompassing the lesion showed dramatic differences in spectral patterns indicative of radiation necrosis, recurrent or residual tumor, or normal brain. The 1H-MRS imaging data demonstrated significant differences between suspected residual or recurrent tumor and contrast-enhancing radiation-induced necrosis. Regions of abnormally high choline (Cho) levels, consistent with viable tumor, were detected beyond the regions of contrast enhancement for all 12 gliomas. Changes in the serial 1H-MRS imaging data were observed, reflecting an altered metabolism following treatment. These changes included the significant reduction in Cho levels after therapy, indicating the transformation of tumor to necrotic tissue. For patients who demonstrated subsequent clinical progression, an increase in Cho levels was observed in regions that previously appeared either normal or necrotic. Several patients showed regional variations in response to brachytherapy as evaluated by 1H-MRS imaging. This study demonstrates the potential of noninvasive 3-D 1H-MRS imaging to discriminate between the formation of contrast-enhancing radiation necrosis and residual or recurrent tumor following brachytherapy. This modality may also allow better definition of tumor extent prior to brachytherapy by detecting the presence of abnormnal metabolite levels in nonenhancing regions of solid tumor.

Aspartic Acid↗
PubMed1997

Providing dental care for patients diagnosed with Alzheimer's disease.

Alzheimer's disease is the most common dementing illness affecting over 4 million Americans. As the population ages, dentists and other health care providers will be faced with the daunting task of managing an increasing number of people with this disease. Currently, there are no definitive medications to treat this disease, although there are a number of recent drugs which may help to alleviate some symptoms. This article reviews the current medical treatment and the dental concerns which face the dentist, patient, and family. Suggestions for dental management are given along with practical recommendations for caregivers.

Aged↗
PubMed1995

Dental amalgam and cognitive function in older women: findings from the Nun Study.

The authors determined the number and surface area of occlusal dental amalgams in a group of 129 Roman Catholic sisters who were 75 to 102 years of age. Findings from this study of women with relatively homogeneous adult lifestyles and environments suggest that existing amalgams are not associated with lower performance on eight different tests of cognitive function.

Aged↗
PubMed1995

Functionally dependent veterans. Issues related to providing and improving their oral health care.

This article discusses issues related to the quality and effectiveness of new, emerging, and existing oral health delivery mechanisms and models for the functionally dependent veteran. It describes the particular needs and unique qualities of functionally dependent veterans and enumerates the clinical dental interventions and delivery systems available to this group. Barriers specific to The Department of Veterans Affairs (VA) regarding this population and suggestions for improved access to care are summarized. Suggestions for further research are proposed with the intent that limited resources be utilized so that maximum benefits are provided to the functionally dependent veterans who need care most. What we know: Among the veteran population and the general population, the oldest cohort of elderly (those age 85 and older) are growing faster than any other age group. The rate of functional dependency increases dramatically with age, from about 10% at age 65 to 69 to about 57% after age 85. Functionally dependent elderly are the most likely group to be home-bound or in nursing homes. Compared with independent elderly, the oral status of functionally dependent elderly tends to be poorer. Functionally dependent elderly have higher rates of tooth loss, greater prevalence of denture-related problems, greater prevalence and severity of dental caries, higher prevalence of gingival and periodontal disease, and typically not seen a dentist in at least 5 years. The Department of Veterans Affairs has several advantages over non-VA settings in delivering dental care to the functionally dependent including the presence and availability of dental clinics at VA medical centers and outpatient facilities, the fact that they are free to eligible VA patients, and the greater knowledge base of the dentists. Although VA is effective in delivering oral care to a small percentage of the total population, it is likely that demand will increase and resources exhausted if certain anticipated changes occur (eg, greater demand for dental care and/or changing dental status, such as more elderly with teeth). Questions that need to be answered: What quality of oral care is VA providing to the functionally dependent veteran? What delivery systems are the most effective in providing care to the functionally dependent elderly? Is there a difference in oral health outcomes when dental personnel serve on patient care teams? What barriers exist for delivering quality oral care for the functionally dependent elderly? How can we eliminate or minimize these barriers?

Activities of Daily Living↗
PubMed1994

Delivering dental care to nursing home and homebound patients.

The growing life expectancy has created a number of challenges for society and for the dental profession. One of these challenges is the increasing number of people, particularly those over age 85, who are considered frail and functionally impaired, who no longer can live independently or participate in the community. If the impairment is severe enough, the older adult may become home-bound or unable to leave the home without assistive aids or, less commonly, institutionalized in a nursing home. The characteristics of the homebound and nursing home resident represent a dramatic contrast from those who are the same age and living in the community: They are older, predominantly female, and have more physical and mental disabilities. In addition, there are differences in oral health characteristics, of which dentists and other health professionals need to be aware. Although there are a number of obstacles and barriers that make providing dental care more difficult for these patients, federal mandates and a growing professional response to develop initiatives for outreach and access are beginning to have an effect. Still the challenge for providing dental care to these groups remains great, and it will take a tremendous effort from many oral health professionals before significant change is evident. There are many professional and personal rewards for providing this care, and we as dental professionals must be committed to seeing that the oral health needs are met for all underserved populations in our society.

Aged↗
PubMed1990

Proliferative mass found in the gingiva.

The clinical course of peripheral ossifying fibroma is slow and the growth of most lesions is limited in size, usually up to 1.5 cm. Complaints are rare unless the surface becomes ulcerated, or the lesion compromises oral function or esthetic appearance. Treatment is surgical excision with close postoperative follow-up. Tooth extraction is seldom necessary. Proper surgical intervention, which includes excision of reactive tissue down to periosteum, affords a low recurrence rate of 14% to 16%.

Fibroma↗
PubMed1983

Monaural studies eliciting an hemispheric asymmetry; a bibliography: II.

Since 1979, 32 behavioral studies using monaural stimulation elicited an hemispheric asymmetry confirming the findings of 74 investigations published between 1967 and 1979, which were compiled by Henry, 1979. 13 psychophysiological studies also using monaural stimulation have been added; they reach the same conclusion.

Bibliographies as Topic↗
PubMed1979

Demonstration by radionuclide imaging of possible vascular steal from a renal transplant.

Radionuclide studies in a renal-transplant patient with congestive heart failure suggested vascular steal from the renal allograft by a contralateral femoral arteriovenous fistula. These reliable, noninvasive diagnostic procedures have potential use in similar settings to evaluate allograft perfusion and function. Correction by removal of the fistula was demonstrated.

Adult↗