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Biomedical subjects

I Fogelman

Publications and source records attributed to I Fogelman.

At least 127 records · Page 7Linked to original sources
PubMed1996

Occupational dose to the radiographer in dual X-ray absorptiometry: a comparison of pencil-beam and fan-beam systems.

The introduction of advanced dual X-ray absorptiometry (DXA) scanners with fan-beam geometry, improved image definition and faster scan times raises the question as to whether there is a significant radiation dose to the radiographer. We have measured the radiation dose to the operator from studies performed on four DXA systems; the Lunar DPX, Hologic QDR-1000, QDR-2000 plus and QDR-4500. The results were compared with the radiographer dose from 99Tcm-MDP radionuclide bone scanning, where it is not usual to use a radiation barrier between the patient and the operator, and 18F-FDG positron emission tomography (PET) scanning where it is usual to protect staff. Ambient dose equivalent rate averaged over 1 h at 1 m from the patient with the DXA systems working at maximum patient throughput were 0.012, 0.12, 2.1 and 2.4 microSv h-1, respectively, for the DPX, QDR-1000, QDR-2000plus and QDR-4500. Annual operator dose for the DPX and QDR-1000 was well below the 1 mSv limit for members of the public recommended by the International Commission on Radiological Protection (ICRP) (1990). Results for the QDR-2000plus and QDR-4500 were similar to a radionuclide bone scan (2.2 microSv h-1), but smaller than for a PET scan (8.9 microSv h-1), and were close to the 5 mSv year-1 limit for a supervised area defined in the 1985 Ionising Radiation Regulations. Precautions to reduce radiographer dose with fan beam DXA include placing the operator at least 2 m from the patient, scanning the right hip instead of the left and using scan modes with short scanning times.

Absorptiometry, Photon↗
PubMed1996

Concordance and precision of dual X-ray absorptiometry with a 10 s scan.

Development of dual energy X-ray absorptiometry (DXA) scanners with multidetector array technology has resulted in greatly shortened scanning times. The Hologic QDR-4500 includes an ultrafast (10 s) "turbo" scan mode recommended by the manufacturer for fast screening studies or as an aid to positioning the patient prior to scanning using the normal fast (30 s), medium (1 min) or high definition (2 min) modes. The suitability of the turbo mode for use in routine clinical studies was assessed by examining the concordance of bone mineral density (BMD) measurements obtained in this mode with measurements obtained using the three normal scanning modes. Studies in 151 female patients showed statistically significant discrepancies in four out of the six scan sites studied with systematic differences of 2.9% and 3.1% being observed for the posteroanterior (PA) spine and intertrochanteric region of the hip, respectively. In vivo precision for the 10 s scan found by performing duplicate measurements on 37 patients had a coefficient of variation of 1.3% for PA spine and 2.5% for femoral neck BMD. An investigation of the dependence of precision on body mass index (BMI) shows that the precision of spine and hip BMD was adversely affected with increasing BMI but the trend was statistically significant only in the spine. It was concluded that turbo mode scans are acceptable for routine clinical studies of the spine and hip but should not be used for longitudinal studies or patients with BMI greater than 30 kg m-2.

Absorptiometry, Photon↗
PubMed1996

SPECT bone scintigraphy of anterior cruciate ligament injury.

UNLABELLED: This retrospective analysis of SPECT bone scans of the knee was undertaken to define typical bone scan appearances and to assess the sensitivity of this method. We looked at 14 patients, mostly with chronic knee pain, who had anterior cruciate ligament (ACL) tears detected by MRI. METHOD: Of the 14 patients, 10 were referred for bone scanning following injury and 4 complained of chronic knee pain without injury. Planar scans were performed 4 hr after the injection of 750 MBq of 99mTc-MDP. Tomographic images were obtained by a 64 x 20-sec acquisition over 360 degrees using a high-resolution collimator. MRI imaging included axial and sagittal, T1 weighted and coronal fast field echo (FFE) sequences. Ten patients also had arthroscopy performed. RESULTS: MRI scans showed 6 lone ACL tears and 8 combined with other ligamentous injuries. SPECT scans showed abnormalities in 10 patients in the region of ACL insertions but only 4 planar studies were abnormal. SPECT identified focal activity at the upper (n = 8) or lower (n = 2) insertion of the ACL. Six of 10 arthroscopies confirmed ACL tears, 2 complete and 4 partial. Overall, agreement was found with MRI in 10 of 14 cases and in 8 of 10 with arthroscopy. Abnormalities were identified in 10 of 11 regions of other ligament or bone injury identified by MRI. CONCLUSION: SPECT bone scanning of the knee is superior to planar imaging in detecting ACL injury and is a sensitive technique. Focal activity may be seen at either end of ACL attachment but more commonly at the upper femoral insertion. Knee SPECT may be a valuable examination in suspected ACL injury, particularly if MRI is not available, is equivocal or where clinical signs are absent.

Adult↗
PubMed1996

Pseudo pulmonary embolism in complex congenital heart disease.

Two children (aged 12 and 14 yr) with a history of complex congenital heart disease presented with symptoms and signs suggestive of pulmonary embolism. Initial ventilation-perfusion lung scans showed normal, approximately equal ventilation to both lungs. Global reduction of perfusion to the right lung was observed in one and was observed in the left lung in the other patient. It was not possible to exclude a large, central embolus in either case. Due to complex cardiac anatomy, however, which included bilateral cavopulmonary anastomoses in the first patient and SVC-right pulmonary artery and right atrial-pulmonary artery anastomoses in the second, repeat scans were performed within a short period in each case with different injection sites, including the contralateral arm and a leg injection, respectively. In both patients, these follow-up scans showed a different perfusion agent distribution to each lung when compared to the initial scans. These results demonstrated that there was no evidence of pulmonary embolism in either case.

Adolescent↗
PubMed1996

The effects of oestrogen deficiency on the skeleton and its prevention.

Increased bone resorption following the menopause leads to accelerated bone loss and is a major contributory factor to subsequent osteoporosis. It is well recognised that an early menopause or prolonged amenorrhoea from whatever cause are also major risk factors for osteoporosis. The alterations in skeletal metabolism following oestrogen deficiency are inhibited by oestrogen replacement, and bone loss can be prevented. However, oestrogen therapy may often not be appropriate because of clinical contraindications, side effects or patient concerns regarding the risk of breast cancer. There is increasing evidence that bisphosphonates are effective in inhibiting bone resorption and these compounds are generally well tolerated. At the present time, for the prevention of bone loss related to hypo-oestrogenism, the main options for therapy are likely to be oestrogen replacement or treatment with bisphosphonates.

Diphosphonates↗
PubMed1995

Hormone replacement therapy and serum angiotensin-converting-enzyme activity in postmenopausal women.

The mechanisms by which hormone replacement therapy (HRT) reduces the risk of coronary heart disease (CHD) are incompletely understood, but may include direct arterial effects. We examined the effect of oestrogen/progestagen HRT on serum angiotensin-converting-enzyme (ACE) activity in postmenopausal women. After 6 months, ACE activity was reduced by 20% (p < 0.001) on average in 28 treated women but remained unchanged in 16 controls. Serum ACE activity is modifiable by gonadal steroids and changes in serum ACE may represent a novel mechanism by which HRT reduces CHD risk in women.

Coronary Disease↗
PubMed1995

The accuracy of volumetric bone density measurements in dual x-ray absorptiometry.

New developments in dual x-ray absorptiometry (DXA) allow the performance of high precision anteroposterior (AP) and lateral scans of spinal bone mineral density (BMD, units: g/cm2) without the patient moving from the supine position. Data from both projections may be combined to give an estimate of the true volumetric bone mineral density (VBMD, units: g/cm3) of the lumbar vertebral bodies. This report presents a cadaver study designed to validate DXA measurements of volumetric bone density. Sections of whole lumbar spine were scanned in AP and lateral projections in a water tank to simulate soft tissue. Individual vertebrae were then divided to separate the vertebral body from the neural arch, and vertebral body volume was measured using the displacement of sand. The bone mineral content (BMC) of vertebral bodies and neural arches was measured by ashing at 250 degrees C for 60 hours followed by 500 degrees C for a further 24 hours. The results showed that DXA scanning systematically underestimated ashing data by 14% for AP BMC, 33% for vertebral body BMC, 23% for vertebral body volume, and 12% for VBMD. Despite these significant systematic errors, the DXA measurements and ashing values were highly correlated (r = 0.979-0.992). The results suggested that after allowing for the systematic errors, lateral DXA parameters related closely to true BMC, volume, and VBMD.

Absorptiometry, Photon↗
PubMed1995

The bone scan: where are we now?

The isotope bone scan continues to be the most widely performed nuclear medicine investigation in the UK. The detection of skeletal metastases remains the most common clinical indication. However, the use of the bone scan is changing as it becomes subject to cost pressures, competing imaging modalities, and altering clinical indications. Overall, fewer studies are being performed for investigation of skeletal metastases, but this decrease in numbers has been compensated by increasing use in benign orthopaedic conditions. Advances such as correlative imaging and single photon emission computer tomography have increased its value and provided new clinical roles. Quantitation has still not achieved widespread usage, although it continues to be helpful to investigate sacroiliitis. Bone positron emission tomography imaging is now possible, although definite clinical roles have yet to be identified. Bone densitometry using dual x-ray absorptiometry is rapidly increasing in availability and usage throughout the UK, and this can be expected to continue to increase over the next few years.

Absorptiometry, Photon↗
PubMed1995

In situ analysis of cytokine responses in experimental murine schistosomiasis.

BACKGROUND: Infection with schistosomiasis results in CD4+ T helper (Th) cell-dependent granulomatous inflammation around parasite eggs. T cell-derived cytokines play a critical role in the induction and subsequent down-modulation of the granulomas. These cytokine responses have been previously examined in lymphoid cell supernatants or in tissue homogenates but have not been examined directly in the local microenvironment of the lesions or in the reacting lymphoid tissues. EXPERIMENTAL DESIGN: With the use of specific mAb, the cytokines IL-2, IFN gamma, IL-4, and IL-10 were investigated by direct immunocytochemical analysis in situ in hepatic egg granulomas and lymphoid organs from acutely and chronically infected mice. Cytokine expression in situ was compared with cytokine production during a secondary response in vitro. RESULTS: All cytokines examined were detected in various amounts in both the hepatic egg granulomas as well as in mesenteric lymph nodes and spleen. The majority of cells expressing the cytokines was found in lymph nodes, and very few were found in granulomas. Relatively small numbers of granulomas contained most of the cytokine-expressing cells, which tended to localize in their periphery. Granulomas and lymphoid organs in the acute disease contained significantly more cytokine-expressing cells in comparison with those from the chronic disease. This observation correlated well with cytokine production in vitro. CONCLUSIONS: Direct immunocytochemical examination in situ was used to detect and measure cytokine-producing cells in hepatic egg granulomas and reacting lymphoid organs of acute and chronic experimental murine schistosomiasis. Observed cytokine patterns suggest that granulomas contain T lymphocytes of both the Th-1 and Th-2 types and that cytokine production occurs during a limited time in the early granuloma. The immunocytochemical technique affords a direct appraisal of amount, dynamics, and localization of cytokine-producing cells in the unperturbed local environment.

Animals↗
PubMed1994

Effects of IL-12 on helper T cell-dependent immune responses in vivo.

The differentiation of naive T cells to the Th1 or Th2 subset of effector cells is regulated by the cytokines to which T cells are exposed at the time of antigenic stimulation. Mice immunized with a hapten-protein conjugate and treated systemically with IL-12 show a marked inhibition of IL-4-secreting cells and suppressed production of anti-hapten IgG1 Ab, as well as a marked enhancement of IFN-gamma-producing T cells. Thus, IL-12 is a potent inhibitor of Th2 differentiation and an inducer of Th1 development in vivo. The IFN-gamma-inducing effect of IL-12 is partially blocked by pretreatment of mice with anti-asialo GM1 (anti-NK cell) Ab, but anti-asialo GM1 does not abrogate any of the other systemic actions of IL-12. Furthermore, none of the effects of IL-12 is prevented by treating mice with neutralizing anti-IFN-gamma Abs. These results suggest that the effects of IL-12 may be mediated both via NK cell stimulation and by directly altering the differentiation patterns of T cells. Finally, a neutralizing anti-IL-12 Ab significantly inhibits Th1 responses to Ag, indicating that IL-12 may play an obligatory role in Ag-induced Th1 differentiation in vivo.

Animals↗
PubMed1994

Fractal signature analysis of macroradiographs measures trabecular organization in lumbar vertebrae of postmenopausal women.

High definition macroradiography was used to provide an image of the detailed structural organization of the cancellous bone in human lumbar vertebrae. The fractal signature analysis (FSA) method was used to quantify the horizontal and vertical trabecular organization recorded within the image. Comparison of the FSA of the postero-anterior and lateral macroradiographs in postmortem lumbar vertebrae showed that neither the superimposition of the neural arch nor the radiographic angle affected the trabecular measurement within the vertebral body. FSA analysis of the trabecular structure measured from the macroradiographs of lumbar vertebrae in two groups of postmenopausal women, with high and low bone mineral density (BMD), showed that the large vertical trabecular structures correlated with the women's body weight (P < 0.01-0.03) and body mass index (P < 0.005-0.05), the fine horizontal structures correlated with the women's age (P < 0.005-0.05), and fine vertical trabecular structures were significantly greater (P < 0.005-0.05) in the low compared with the high BMD group.

Adult↗
PubMed1994

Effect of tibolone on postmenopausal bone loss.

A 2-year non-randomized prospective study was carried out in a teaching hospital menopause clinic to assess the effect on the skeleton of tibolone (Livial, Organon) 2.5 mg daily in recently postmenopausal women. One hundred women who were between 6 and 36 months since their last menstrual period and had raised gonadotrophin levels consistent with the menopause were allocated into two groups. One group received 2.5 mg tibolone daily and the other group no medication. Bone densitometry of the spine and femur was performed at 0, 6, 12 and 24 months and biochemical markers of bone metabolism were assessed at these points. Severity of hypo-oestrogenic symptoms was assessed at baseline and at 1 and 2 years. After 2 years there was a significant increase in bone mass as measured by dual energy X-ray absorptiometry (DXA) of 2.5% in the spine, and 3.5% in the neck of femur in the women who took tibolone (n = 46), whereas in the control group (n = 45) bone loss occurred (spine, 2.9%; femur, 3.7%). When these changes were compared they were significantly different for both sites (p < 0.001). In the treatment group the urinary hydroxyproline/creatinine and calcium/creatinine ratios fell from 0.014 (0.002-0.027) to 0.010 (0.000-0.111) (mol/l) (mmol/l) (p < 0.01) and 0.47 (0.08-0.96) to 0.33 (0.09-1.20) (mmol/l) (mmol/l) (p < 0.001) respectively, while the serum osteocalcin and alkaline phosphatase decreased from 1.90 (0.20-4.70) to 1.00 (0.00-3.00) mmol/l (p < 0.01) and 190 (92-301) to 138 (91-283) mmol/l (p < 0.001) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Distribution of bone mineral density in the lumbar spine in health and osteoporosis.

The significance of variability in bone mineral density (BMD) between lumbar vertebrae L1 to L4 in the same individual was investigated by dual-energy X-ray absorptiometry in 1000 normal women aged 40-60 years (average 52 years) and 145 women aged 45-80 years (average 65 years) with vertebral osteoporosis. The mean BMD increased from L1 to L4 in normal women from 0.841 g/cm2 to 1.017 g/cm2, and in osteoporotics from 0.562 g/cm2 to 0.709 g/cm2. Z scores for osteoporotic women (Z = osteoporotic BMD - age-normal BMD/normal SD) were significantly lower for individual vertebrae compared with L1-4 and at L4 compared with L1, L2 and L3 (p < 0.001). The mean difference between Z scores for the highest and lowest vertebrae in an individual was 0.70 for normals (SD = 0.40) and 0.64 for osteoporotics (SD = 0.36). The mean Z score difference between the L1-4 Z score and the lowest individual vertebral Z score was 0.36 for normals (SD = 0.23) and 0.06 for osteoporotics (SD = 0.31). However, receiver operating analysis (ROC) curves showed that the lowest Z score for any individual vertebra did not provide improved discrimination between normals and osteoporotics when compared with the L1-4 Z score. The area under the ROC curve for L1-4 was significantly greater than for individual vertebrae (p < 0.05) and that for L4 was significantly smaller than for L1, L2 or L3 (p < 0.001). In conclusion, L1-4 BMD gives greater diagnostic sensitivity for osteoporosis than individual vertebrae, and L1, L2 and L3 are better than L4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Clinical experience with etidronate in osteoporosis.

Clinical experience with cyclical etidronate for the treatment of osteoporosis was reviewed in 69 consecutive patients. Six patients stopped treatment either due to adverse effects (5) or the decision to take hormone replacement therapy (HRT) (1). Bone mineral density (BMD) measurements using dual energy X-ray absorptiometry (DXA) were obtained in 63 patients (33 with spinal osteoporotic fractures and 30 with osteopenia) before and 1 year after treatment. BMD increased by an average of 4.50% (p < 0.001) in the lumbar spine (range +14% to -12%) and 5.5% (p < 0.01) at Ward's triangle (range +31% to -13%) while there was no significant change at the femoral neck (range +11% to -12%) and greater trochanter (range +12% to -15%). Significant rises in BMD were found at the lumbar spine and Ward's triangle in both osteoporotic and osteopenic groups. Of patients analysed after 1 year, 83% had an increased bone mass at the lumbar spine and 55% at the femoral neck. We conclude that there is a wide variation in the bone mass response to cyclical etidronate therapy, and in a minority of patients bone mass does not increase. For the majority of osteoporotic patients, however, we confirm the efficacy and tolerability of cyclical etidronate for the preservation of bone mass over 1 year in a clinical setting.

Absorptiometry, Photon↗
PubMed1994

Patient dose in dual x-ray absorptiometry.

Dual x-ray absorptiometry (DXA) provides a convenient, non-invasive method of assessing skeletal bone mineral which is widely used for clinical studies. This report describes a study to estimate the effective dose of radiation (ICRP-60 (1990)) to a typical female patient from scans performed on three DXA scanners: the Hologic QDR-1000, QDR-1000/W and QDR-2000. The scans modes studied were: total body; anteroposterior (AP) lumbar spine; lateral lumbar spine; proximal femur; distal forearm. An ionization chamber and tissue-equivalent phantom were used to determine entrance surface dose and percentage depth-dose curves for each scan mode. Anatomical data from ICRP-23 (Reference Man) and a body section atlas were used to estimate the absorbed dose to each organ in the scan fields. Effective dose was estimated using the ICRP-60 tissue weighting factors and the fraction of each organ in the scan field. Results are summarized below. Figures for the effective dose are given both excluding and (in brackets) including the ovaries to cover the cases of postmenopausal and premenopausal women respectively.

Absorptiometry, Photon↗
PubMed1994

A study of the effect of tibolone on the vagina in postmenopausal women.

Tibolone is a synthetic compound with weak oestrogenic, progestagenic and androgenic properties. It does not appear to stimulate the endometrium, and therefore has appeal to the postmenopausal woman as a 'bleedfree' form of hormone replacement therapy (HRT). In the present study the vaginal cytological findings and symptoms were evaluated in 100 recently postmenopausal women, 50 of whom were started on tibolone 2.5 mg daily and 50 of whom received no medication. After 2 years in the tibolone group, cytological assessment showed a significant increase in the karyopyknotic index (P < 0.001) and maturation value (P < 0.01) whereas there was no change in the control group. Significant symptomatic improvement occurred in vaginal dryness (P < 0.001), dyspareunia (P < 0.001), sexual enjoyment (P < 0.001) and libido (P < 0.05). It is therefore concluded that tibolone has a significant oestrogenic effect on the vagina as demonstrated by vaginal cytology. In addition, improvement in the symptoms of vaginal dryness, dyspareunia, sexual enjoyment and libido occurs.

Estrogen Replacement Therapy↗