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Biomedical subjects

R W Whitehouse

Publications and source records attributed to R W Whitehouse.

At least 19 recordsLinked to original sources

The influence of chemical shift artifact on magnetic resonance imaging of the ligamentum flavum at 0.5 tesla.

STUDY DESIGN: Retrospective clinical magnetic resonance imaging study and prospective magnetic resonance imaging volunteer study of the appearance of the ligamentum flavum. OBJECTIVE: To demonstrate the effect of chemical shift artifact on the apparent thickness of the ligamentum flavum on axial magnetic resonance images. SUMMARY OF BACKGROUND DATA: The ligamentum flavum is a symmetric structure clearly seen on magnetic resonance images. Apparent unilateral thickening may be interpreted as indicating a pathologic process, and the influence of chemical shift artifact on the apparent thickness of the ligamentum flavum has not been emphasized. METHODS: Ligamenta flava thicknesses were measured from axial T1-weighted gradient echo magnetic resonance scans of 12 consecutive patients and various axial sequences in seven volunteers. RESULTS: The ligamentum flavum appeared consistently thicker on the lower side of the readout gradient field. This chemical shift effect could be manipulated by swapping phase and frequency or patient orientation in the magnet. CONCLUSIONS: Caution should be applied in attributing apparent asymmetry of the ligamenta flava to disease; the influence of chemical shift artifact should be considered.

Adolescent

Application of computer texture analysis to the Singh Index.

The Singh Index, which describes trabecular patterns in the proximal femur, has been used as a predictor for hip fractures and as an indicator of osteopenia. Evidence suggests that its contribution to the assessment of hip fracture risk is in its description of the structural properties of the femur. However, subjectivity in its determination may limit its practical value. In this study, we have used computer texture analysis to characterize the textural changes in trabecular bone which occur in osteoporosis. Texture analysis of the proximal femur was used to rank radiographs of 25 cadaver femora by Singh grading. These rankings were compared with those performed by two experienced radiologists. The computer method performed better than the least consistent individual radiologist, but not as well as the two radiologists in combination. The method required no radiologist's time after the system had been 'trained' from a set of example radiographs. The method has potential for use in large studies in which speed and consistency of measurement are important.

Bone Density

Enlargement of the tensor intermuscularis muscle in Graves' ophthalmopathy. A computed tomographic and magnetic resonance imaging study.

OBJECTIVE: To determine whether the tensor intermuscularis muscle (TIM), which consists of muscle fibers in the superolateral intermuscular orbital septum, is involved in Graves' ophthalmopathy (GO). DESIGN: The computed tomographic (n = 24) and magnetic resonance imaging (n = 10) appearances of the TIM were retrospectively examined in 34 patients with known GO. The severity of GO was assessed by applying a scoring system from 0 to 3 (ie, normal [0], mild [1], moderate [2], and severe [3]) to each of the rectus muscles and superior oblique muscle. The severity of exophthalmos, enlargement of the superior ophthalmic vein, and displacement of the lacrimal gland were also recorded. RESULTS: The TIM appeared as thickening of the septum immediately behind the globe, and it was best seen on coronal magnetic resonance images. There was enlargement of the TIM in 19 of the 34 patients, and it was bilateral in 17. Enlargement was present only in patients with moderate or severe involvement of other muscles (muscle index, > 7/15), and it was significantly correlated with the muscle index (P < .05), exophthalmos (P < .05), enlargement of the superior ophthalmic vein (P < .005), and anterior displacement of the lacrimal gland (P < .01). Severe enlargement of the TIM was seen in only five of the 34 patients, and it showed a close correlation with the muscle index (P < .005), exophthalmos (P < .001), enlargement of the superior ophthalmic vein (P < .001), and anterior displacement of the lacrimal gland (P < .001). CONCLUSIONS: Enlargement of the TIM in GO can be identified on computed tomographic and magnetic resonance imaging scans. It is invariably associated with moderate or severe involvement of other extraocular muscles, and it correlates closely with other well-recognized imaging features of severe GO.

Adult

Further increase in forearm cortical bone mineral content after discontinuation of growth hormone replacement.

OBJECTIVE: Growth hormone replacement of adults with childhood onset GH deficiency results in an increase in bone mineral density (BMD) after 6-12 months of GH replacement. By measuring BMD 12 months after discontinuation of GH replacement we aimed to investigate whether there is an effect of GH replacement on BMD persisting after GH has been withdrawn. DESIGN: BMD was measured 13 +/- 1 (mean +/- SE, range 11-16) months after discontinuation of GH replacement. PATIENTS: Ten adults, age 23.2 +/- 1.4 (range 18.8-32.4) years, with childhood onset isolated GH deficiency (2 idiopathic, 8 irradiation induced) who had previously completed a study of the effect of 12 months of GH replacement on BMD. MEASUREMENTS: Forearm cortical bone mineral content (BMC) was measured using single-photon absorptiometry at the proximal site of the distal forearm. Forearm integral BMC at the ultradistal site of the forearm and bone width at both proximal and ultradistal sites of the distal forearm were measured by the same technique. Vertebral trabecular BMD was measured using quantitative computed tomography. RESULTS: Forearm cortical BMC was significantly greater than that measured at the time of discontinuation of GH (1.48 +/- 0.04 vs 1.44 +/- 0.05 g/cm). There was no significant change in forearm integral BMC or in vertebral trabecular BMD after discontinuation of GH. There was no significant change in bone width at proximal and ultradistal sites of the distal forearm after discontinuation of GH. CONCLUSION: After discontinuation of GH replacement the further increase in forearm cortical bone mineral content without a significant increase in forearm bone width suggests that the increase in cortical bone mineral content is due to a persisting effect of previous GH replacement, and not to further spontaneous attainment of bone mass before peak bone mass is reached. These findings emphasize the importance of continuing to monitor bone mass after the stimulus to increase bone turnover has been withdrawn.

Absorptiometry, Photon

Effect of growth hormone replacement on bone mass in adults with adult onset growth hormone deficiency.

OBJECTIVE: Previous studies of the effect of GH replacement on bone mass in adults with GH deficiency have produced conflicting results. We have studied the effect of 6 and 12 months of GH replacement on bone mass in adults with adult onset GH deficiency. DESIGN: Double blind placebo controlled study of GH replacement (0.125 IU/kg/week for the first month and 0.25 IU/kg/week thereafter) for 6 months and an open study for a further 6 or 12 months. PATIENTS: Twenty-two adults (10 men, 12 women), aged 41.5 +/- 2.1 years (mean +/- SE, range 23.6-59.5), with adult onset GH deficiency. MEASUREMENTS: Single-energy quantitative computed tomography was used to measure vertebral trabecular bone mineral density (BMD), single-photon absorptiometry (SPA) was used to measure forearm cortical and integral bone mineral content and BMD and dual-energy X-ray absorptiometry (DXA) was used to measure lumbar spine, femoral neck, trochanteric and Ward's triangle integral BMD. RESULTS: After 6 months of GH replacement (n = 21) there was a significant decrease in forearm cortical BMD (SPA: median change -0.009 g/cm2, P = 0.01), forearm integral BMD (SPA: median change -0.016 g/cm2, P = 0.03), lumbar spine BMD (DXA: median change -0.22 g/cm2; P = 0.003) and femoral neck BMD (DXA: median change -0.029 g/cm2, P = 0.006). After 12 months of GH replacement (n = 13) there was a significant decrease in lumbar spine BMD (DXA: median change -0.035 g/cm2, P = 0.002) from baseline. There was no significant increase in bone mass at any site after 6 or 12 months of GH replacement. Change in bone mass was not influenced by sex of the patient or by presence or absence of additional pituitary hormone deficiencies. CONCLUSION: The response of bone mass to 6 and 12 months of GH replacement in adults with adult onset GH deficiency is disappointing. Longer-term studies are required to determine whether prolonged GH replacement has a beneficial effect on bone mass.

Adult

Reduced bone mineral density in men following chemotherapy for Hodgkin's disease.

We have measured bone mineral density (BMD) in 29 men, mean age 35.0 (range 19.7-58.0) years, with testicular damage following MVPP or hybrid chemotherapy for Hodgkin's disease. Forearm cortical bone mineral content (BMC) and lumbar spine and femoral neck integral BMD were measured 3.4 (1.1-6.8) years after completion of chemotherapy, and results expressed as Z (standard deviation) scores. There was a significant reduction in forearm cortical BMC (median BMC 1.727 g cm-1, median Z-score -0.8, P < 0.0005), in lumbar spine integral BMD (median BMD 1.141 g cm-2, median Z-score -0.6, P < 0.0005) and in femoral neck integral BMD (median BMD 0.991 g cm-2, median Z-score -0.4, P < 0.05). There was no significant correlation between Z-score and time elapsed since completion of chemotherapy, and no significant difference in Z-score according to type of chemotherapeutic regimen or number of cycles of chemotherapy received. In conclusion, men who are in complete remission following treatment of Hodgkin's disease have reduced cortical and trabecular BMD. Possible causes include mild hypogonadism secondary to chemotherapy-induced impairment of Leydig cell function, a direct effect of chemotherapy on bone, an effect of high-dose glucocorticoid on bone or an effect of Hodgkin's disease per se.

Adult

Non-expression of von Hippel-Lindau phenotype in an obligate gene carrier.

Von Hippel-Lindau disease is generally considered to be a condition with very high penetrance, and individuals who live beyond the age of 60 years without showing any features of the disease, despite undoubtedly carrying the gene defect, have not previously been clearly described. The case is presented of a 65-year-old woman, who had four siblings affected with von Hippel-Lindau disease and had six children, three of whom died young with complications of von Hippel-Lindau disease. Although she is an obligate gene carrier, she has not developed any significant manifestations of the disease despite careful screening for the neurological, retinal and renal complications.

Aged

Prediction of enophthalmos by computed tomography after 'blow out' orbital fracture.

In 11 patients with blow out fracture of the orbit, measurement of orbital volume using computed tomography (CT) more than 20 days after injury correlated well with enophthalmos measured from the same scans (r = 0.87, p < 0.001, SEE 0.63 mm), with a 1 cm3 increase in orbital volume causing 0.8 mm of enophthalmos. This confirms the cause of enophthalmos after blow out fracture to be increase in orbital volume rather than fat atrophy or fibrosis. In a further 25 patients scanned within 20 days of injury the degree of enophthalmos was less marked than would be predicted from the orbital volume measurement. This was probably because of the presence of oedema, haemorrhage, or both behind the globe which would prevent immediate development of enophthalmos. CT measurement of orbital volume within 20 days of injury may predict the final degree of enophthalmos and identify those patients at risk of late enophthalmos, allowing appropriate early surgical intervention.

Enophthalmos

Histological, radiological, and biochemical features of the adynamic bone lesion in continuous ambulatory peritoneal dialysis patients.

Adynamic bone is being found with increasing frequency in dialysis patients. Little is known about its aetiology, and even less about its natural history. We found 10 cases of asymptomatic adynamic bone among a group of 32 continuous ambulatory peritoneal dialysis patients, most of whom had never been exposed to aluminium-containing phosphate binders. Compared to the remaining 22 patients, they had an older mean age (54 +/- 11.4 vs. 42 +/- 11.8 years; p < 0.05), probably a longer pre-dialysis duration of renal failure (10.9 vs. 7.1 years), higher mean ionized calcium (1.30 +/- 0.04 vs. 1.15 +/- 0.02 mmol/l; p < 0.01), and lower mean intact parathyroid hormone (31.5 vs. 200.3 pg/ml; p < 0.001). The bone density was not different between the two groups, but 9 of the 10 adynamic patients had significant vascular calcification seen on plain radiology as compared with only 7 of 20 in the comparison group (p < 0.05). Follow-up of the adynamic patients showed a close association with serum intact parathyroid hormone and ionized calcium levels. With one exception, adynamic bone did not appear to be associated with lower bone density than other types of osteodystrophy, but a longer-term study is required to determine the complete natural history of this lesion.

Adult

Reduced bone mineral density in patients with adult onset growth hormone deficiency.

We have demonstrated previously that adults with isolated GH deficiency of childhood onset have a reduced bone mineral density (BMD) of vertebral trabecular bone [quantitative computed tomography (QCT): median Z score -1.3, P < 0.01, n = 12] and of cortical bone in the forearm [single photon absorptiometry (SPA): median Z score -2.9, P = 0.001, n = 7]. We have now examined BMD in 26 patients (13 men, 13 women), aged between 23.6 and 59.5 (mean 42.4) yr, with adult onset GH deficiency, defined as a GH response of less than 5 micrograms/L to provocative testing, of at least two years duration. BMD was measured using QCT for vertebral trabecular bone, dual energy x-ray absorptiometry (DXA) in the lumbar spine and femoral neck, and SPA in the forearm. There was a highly significant reduction in QCT (median Z score -1.07, P < 0.00005), in DXA of the lumbar spine (median Z score -0.76, P = 0.0001) and in SPA of the forearm (median Z score -0.86, P = 0.0001) but not in DXA of the femoral neck (median Z score -0.38, P = 0.35). There were no significant differences in Z scores between those patients with isolated GH deficiency and those with GH and gonadotrophin deficiency. There was a significant positive correlation between age at which BMD was measured and Z score (the older the patient, the higher the Z score) for QCT (r = 0.38, P < 0.05) and SPA (r = 0.48, P < 0.01) with a trend to a positive correlation for DXA of the lumbar spine and femoral neck. Patients were grouped according to estimated duration of GH deficiency (less than 5 yr, n = 7; 5-10 yr, n = 10; greater than 10 yr, n = 9). These groups did not show a significant difference in BMD at any site. We conclude that patients with adult onset GH deficiency (isolated or in conjunction with other pituitary hormone deficiencies) have a reduced BMD. Age at development of GH deficiency may be more important than duration of GH deficiency in determining the degree of reduction in bone mass. The impact of GH treatment on BMD in adults with adult onset GH deficiency requires investigation.

Absorptiometry, Photon

Radiological appearance of clinical inflammatory sinus disease with bone destruction. The significance of contrast enhancement.

It is generally accepted that conventional imaging techniques have limitations in their ability to differentiate benign and malignant disease processes resulting in bone destruction. Although computed tomography (CT) has proved helpful in the diagnosis of such lesions in the paranasal sinuses, the underlying radiological criteria are unclear and the value of contrast enhancement appears limited. Conventional radiographs and CT scans, with dynamic contrast infusion, from five patients in whom a provisional diagnosis of antral carcinoma had been made were reviewed in the light of a subsequent histopathological diagnosis of benign inflammatory disease. In four of these patients, a band of enhancement was demonstrated to parallel the antral walls which, in three cases, remained intact despite underlying bony defects. Their finding is significant in that it demonstrates mucosal integrity, thus making the radiological diagnosis of antral carcinoma less attractive and allowing assessment of the extent of inflammatory soft tissue changes. Thus the use of contrast-enhanced CT is recommended in the assessment of patients in whom sinus disease with bone destruction has been identified on conventional radiographic examination.

Adult

Correlation of bone histology with parathyroid hormone, vitamin D3, and radiology in end-stage renal disease.

We analyzed transiliac bone biopsy specimens from 30 end-stage renal failure patients, taken at the time of admission for CAPD training. Results were compared with values of iPTH, bone alkaline phosphatase, 1,25-dihydroxyvitamin D3, skeletal survey, quantitative computed tomography (QCT) and single photon absorptiometry (SPA) bone density measurements. Osteitis fibrosa was the most common histological diagnosis, present in 15 of the 30 patients (50%), with eight classified as "severe" and seven as "mild." Eight patients (27%) had adynamic bone lesion, four mixed renal osteodystrophy (13%), and two (7%) osteomalacia. The mean age of the adynamic group was higher than the osteitis fibrosa group (41 +/- 12.1 vs. 56 +/- 10.2 years; P < 0.01), and than the mixed group (39 +/- 7.5 vs. 56 +/- 10.2 years; P < 0.02). Levels of iPTH enabled discrimination between groups, but not between individual patients, and values correlated with bone alkaline phosphatase (r = 0.62; P < 0.001). Erosion of the terminal phalanges was seen on the plain X-rays of 7 of 15 patients with mild or severe OF, and in three patients with another diagnosis. The majority of patients (> 90%) had bone density measurements within the normal range. No significant correlation existed between QCT or SPA scores and any of the histomorphometric parameters, or iPTH. We conclude that iPTH is the most helpful non-invasive investigation in this group of patients. Plain X-ray of the hands is the most useful radiological investigation, but single measurements of bone density are not diagnostic.

Adult

Orbital volume measurement in the management of pure blowout fractures of the orbital floor.

With the recent advent of accurate orbital volume assessment by computed tomography, a retrospective analysis was made of 31 patients with 'pure' blowout fracture of the orbital floor, managed either surgically or conservatively, to determine whether orbital volume measurement could provide an additional parameter of use in the management of such fractures. There was a significant difference in orbital volume discrepancy between patients managed surgically or conservatively suggesting that this investigation may be of use in decision making on surgical intervention in patients with orbital blowout fractures.

Anthropometry

Increased bone density after recombinant human growth hormone (GH) therapy in adults with isolated GH deficiency.

The physiological role of GH in the adult skeleton is unknown. In this study, 12 adults (10 males and 2 females) with isolated GH deficiency were treated with GH as a single daily sc injection (0.125 IU/kg.week for the first 4 weeks and subsequently at 0.25 IU/kg.week) for 1 yr in a double blind, placebo-controlled manner. Bone mineral density of the spine (T12-L3) was measured by quantitative computed tomography, and bone mineral content (BMC) of the forearm by single photon absorptiometry at entry into the study and subsequently at 6 monthly intervals. All baseline bone mineral measurements were reduced compared with those in an age- and sex-matched control population. In the treatment cohort, quantitative computed tomography spinal trabecular bone mineral density increased by 7.8 g/L after 6 months of GH replacement (mean +/- SEM, 151.7 +/- 6.0 vs. 159.5 +/- 5.9 g/L; n = 11; P < 0.01), and this increment was maintained at 1 yr (160.7 +/- 6.3 g/L). Proximal forearm (cortical) BMC showed no change after 6 months of GH replacement, but there was a significant increase of 0.06 g/cm after 12 months of GH replacement (from 1.38 +/- 0.04 to 1.44 +/- 0.04 g/cm; n = 12; P < 0.05). Distal forearm (cortical and trabecular) BMC also increased significantly during the study period from 1.46 +/- 0.04 g/cm to 1.52 +/- 0.05 g/cm; n = 12, P < 0.05. No significant changes occurred in bone mineral measurements during 6 months of placebo therapy. Midthigh muscle and fat cross-sectional area increased and decreased, respectively, during the active treatment phase. These results demonstrate that GH plays an important role in maintaining the integrity of the adult skeleton.

Adipose Tissue