Double-phase parathyroid scintigraphy in dogs using technetium-99M-sestamibi.

The purpose of this study was to evaluate the utility of double-phase parathyroid scintigraphy using 99mTc-sestamibi for detecting and localizing hyperfunctioning parathyroid glands in hypercalcemic dogs. Fifteen hypercalcemic dogs that underwent parathyroid scintigraphy were included in this study: 3 dogs with hypercalcemia of malignancy, and 12 dogs with hyperfunctioning parathyroid tissue (parathyroid adenoma or parathyroid hyperplasia). The presence of parathyroid adenoma or parathyroid hyperplasia was documented by histopathologic examination. In 3 dogs with hypercalcemia of malignancy, parathyroid scintigraphy was negative for hyperfunctioning parathyroid tissue and the scans were classified as true negative. Parathyroid scintigraphy correctly identified the presence and location of hyperfunctioning parathyroid tissue in only 1 of 6 dogs with a parathyroid adenoma. False positive and false negative results occurred in dogs with parathyroid adenomas. Parathyroid scintigraphy failed to detect hyperfunctioning parathyroid tissue in 5 of 6 dogs with parathyroid hyperplasia and were classified as false negative. False positive results were obtained in the remaining dog with parathyroid hyperplasia. Sensitivity of parathyroid scintigraphy for detecting and localizing hyperfunctioning parathyroid tissue was 11%, specificity was 50%, and overall accuracy was 27%. Positive and negative predictive value were 25% and 27%, respectively. Sensitivity for detection of parathyroid adenomas was 25%, and sensitivity for detection of hyperplastic glands was 0 %. Results of this study indicate that double-phase parathyroid scintigraphy does not appear to have acceptable accuracy in detecting hyperfunctioning parathyroid glands in dogs. Due to the poor sensitivity and specificity of the technique in dogs, parathyroid scintigraphy is not recommended for definitive identification of abnormal parathyroid glands as the cause of hypercalcemia in dogs.

Effect of ischemia and reperfusion on neutrophil accumulation in equine microvascular tissue flaps.

OBJECTIVE: To investigate neutrophil accumulation after ischemia and reperfusion (IR) in microvascular tissue flaps in horses. STUDY DESIGN: Randomized controlled experiment. SAMPLE POPULATION: A total of 8 horses between 1 and 10 years of age, 4 of each sex. METHODS: Control and experimental myocutaneous island flaps based on the superficial branch of the deep circumflex iliac vessels were dissected on each horse. Atraumatic vascular clamps were applied to the pedicle of the experimental flap for 90 minutes and then removed to allow reperfusion. Based on the assumption that rapid infiltration of neutrophils into affected tissues is a hallmark of IR injury, radiolabeled autogenous leukocytes were used to indirectly quantify neutrophil accumulation in flap tissues. Labeled leukocytes were administered through a jugular catheter 30 minutes before flap reperfusion. Biopsies were collected from each flap over a 6 hour postischemia time period; in group 1 (n = 4) from 0 to 6 hours postischemia, and in group 2 (n = 4) from 24 to 30 hours postischemia. Biopsies were examined scintigraphically and histologically for evidence of neutrophil infiltration. RESULTS: All control flaps survived and 6 of 8 experimental flaps survived. There was no significant evidence of acute neutrophil infiltration into flap tissues after reperfusion in either group. CONCLUSIONS: The results of this study suggest that equine myocutaneous flap tissues can survive a 90-minute ischemic period and reperfusion. No significant evidence of the occurrence of IR injury in flap tissues was found. CLINICAL RELEVANCE: The reasons for the previously reported failures of equine free tissue transfer remain uncertain, but they do not appear to be caused by neutrophil mediated injury associated with ischemia and reperfusion.

Relative distribution of blood flow in rats during surface and submerged swimming.

The relative distribution of blood flow was investigated in conscious rats with a radiological imaging technique that utilizes technetium-99m ethyl cysteinate dimer (99mTc-ECD). The objective of the study was to determine the effects of locomotory activity on the distribution of blood flow during a dive response. We compared the relative distribution of systemic flow in rats at rest, surface swimming and during periods of voluntarily initiated underwater swimming. The pattern of blood flow differed considerably between the three groups of rats. In resting controls, blood flow was widely distributed throughout the whole body with the thoraco-abdominal region receiving the largest fraction of cardiac output. During surface swimming blood shifted towards the exercising limbs, while during underwater swimming systemic blood flow was largely restricted to the head and thorax. However, the active front and hind limbs were not rendered totally ischemic. This suggests that the demands of exercising skeletal muscle partially over-ride the peripheral vasoconstriction during asphyxic diving in conscious rats. Furthermore, relative blood flow to the head increased during underwater swimming, which supports the view that there is a preferential maintenance of blood flow to the brain.

A general method for measurement of the time integral of variant magnetic field gradients: application to 2D spiral imaging.

A new method is proposed by which the time integral of time-varying magnetic fields in different voxels can be determined by MRI. A further processing step is employed which enables the integral of the magnetic field gradients experienced by groups of voxels to be deduced. Analysis of the theoretical background and complete simulations have been used to assess the limitations of the technique and the method is applied to the measurement of a 2D spiral k-space trajectory and also of its 1D components. These measured trajectories have been used to reconstruct images from experimental spiral-scan raw data of a phantom acquired using the 2D spiral k-space trajectory. Comparisons of the resulting images are made with the image reconstructed using the corresponding theoretical trajectory. The importance of the repeatability, reliability and accuracy of the technique is demonstrated.

Bone densitometry in Canadian children 8-17 years of Age.

Normative bone mineral density (BMD) and bone mineral content (BMC) values for the total body (TB), proximal femur (PF), and antero-posterior lumbar spine (LS) were obtained from a large cross-sectional sample of children and adolescents who were 8-17 years of age. There were 977 scans for the TB, 892 for the PF, and 666 for the LS; bone mineral values were obtained using a HOLOGIC QDR 2000 in array mode. Data are presented for the subregions of the PF (femoral neck, trochanter, intertrochanter, and the total region) and for the LS (L1-L4 and L3). Female and male values for the FN, LS (L1-L4), and the TB were compared across age groups using a two-way ANOVA. In addition, we compared the 17-year-old female values to a separate sample of young adult women (age 21). At all these sites, BMC and BMD increased significantly with age. There was no gender difference in TB BMC until age 14 or in TB BMD until age 16, when male values were significantly greater. Females had significantly greater LS BMC at ages 12 and 13, but by age 17 the male values were significantly greater. Females had significantly greater LS BMD across all age groups, however. Males had significantly greater FN BMC and BMD across all age groups. There were no significant differences in BMC or BMD at any sites between the 17- and 21-year-old women.

Use of technetium Tc 99m sestamibi for detection of a parathyroid adenoma in a dog with primary hyperparathyroidism.

Double-phase parathyroid gland scintigraphy, using technetium Tc 99m sestamibi, correctly identified the existence and location of a parathyroid adenoma in a dog with primary hyperparathyroidism. The parathyroid adenoma was removed surgically 2 days after scintigraphy. An area of focal radionuclide uptake persisted in the region corresponding to the left external parathyroid gland in the delayed-phase image. Delayed-phase images from 3 healthy dogs and a dog with hypercalcemia of malignancy caused by lymphoma did not reveal an area of persistent radiotracer uptake. Double-phase parathyroid gland scintigraphy, using 99mTc-sestamibi, is a simple, rapid, noninvasive test, which can be used for detection and localization of parathyroid adenomas in hypercalcemic dogs. It also can help to differentiate these dogs from dogs with hypercalcemia of malignancy.

Comparison of areal and estimated volumetric bone mineral density values between older men and women.

We compared areal bone mineral density (BMD) of the total body (TBMD), antero-posterior lumbar spine at L3 (APS), lateral spine at L3 (LS) and femoral neck (FN). In order to understand better the effect of gender-related size differences on BMD, we also compared the estimated volumetric BMD at L3 (VLS) and the femoral neck (VFN). Subjects were asymptomatic women (n = 22) and men (n = 44) with an age range of 58-79 years. BMD at each site was measured by dual-energy X-ray absorptiometry using a Hologic 2000 in array mode. Results of the statistical analyses (ANOVA) showed the men to have significantly greater BMD at all areal sites [APS, LS (p < 0.05); FN (p < 0.01); TBMD (p < 0.001)]. The two estimated volumetric comparisons, however, showed no gender differences. Results demonstrate how measures from areal BMD measures can be misleading when comparing groups of different size. In older men and women planar measures may overestimate gender differences in BMD.

Familial comparison of bone mineral density at the proximal femur and lumbar spine.

Familial resemblance of bone mineral density (BMD) was studied in the lumbar spine and three regions of the proximal femur in 41 biological mother-daughter (M-D), 42 mother-son (M-S), 24 mother-grandmother (M-G) pairs and 18 mother-grandmother-daughter (M-G-D) triads. Children were placed into three maturity categories based on an assessment of secondary sex characteristics and growth velocities. Two sets of standardized BMD Z-scores were derived for the children based on either their chronological age or their maturational status. These scores were compared with maternal Z-scores derived from age-specific norms. Similar comparisons were made between the Z-scores of the mothers and grandmothers. For all three regions of the proximal femur and for the total AP lumbar spine the correlations between Z-score values were similar and significant (P < 0.05) between the M-G and M-D pairs ranging from 0.41 to 0.57. In general, the familial correlations improved when maturity-status based Z-scores were used for comparison. The absolute BMD values measured in the grandmothers and the three maturity groups of the children--expressed as a percentage of the BMD of the mothers--showed that at the neck and the trochanteric regions of the proximal femur the late-pubescent girls and boys had a significantly (P < 0.05) greater bone density than their mothers (115-123%), whereas at the AP spine these groups averaged only 88% of their mothers BMD. This site differential was not apparent when comparing the post-menopausal grandmothers with the pre-menopausal mothers (80% at both sites). Three generation comparisons demonstrated a strong familial resemblance in bone mineral density. The value of incorporating maturity-based versus chronological-based parameters for comparison with adult measures in studies that involve growing children at different stages of development was also demonstrated.

Regional and total body bone mineral content, bone mineral density, and total body tissue composition in children 8-16 years of age.

Normative values for total body bone mineral content (TBBM) and total body bone mineral density (TBMD) were derived from measurements on 234 children 8-16 years of age. In addition, bone mineral content (BMC) and bone mineral density (BMD) values for selected regions of interest and soft tissue (bone free lean and fat) for the total body are presented. Bone mineral and soft tissue values were determined by dual energy X-ray absorptiometry (DXA) using a Hologic QDR-2000 in the array mode. Results of a stepwise multiple regression analysis revealed a significant correlation between bone-free lean tissue (BFLT) and BMD (r2 = 0.80) in girls. Adding age to the equation accounted for an additional 2% of the variance (P < 0.05) and height accounted for another 1% of the variance (P < 0.05). Body weight and fat tissue (FT) did not account for any additional variance. In boys BFLT correlated significantly with BMD (r2 = 0.75; P < 0.05); none of the other predictor variables accounted for additional variance. No significant differences were found in TBBM or TBMD between boys and girls at any age. There was a significant overall gender effect for only three regions of interest. Boys had greater BMC in the head region and had greater BMD in the upper limbs, but post hoc analysis revealed no significant differences for any specific age groups. Girls had greater overall BMD in the pelvis, but this difference was only significant at the 15-16-year age group. The changes in BFLT and FT over the age ranges were consistent with the growth literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of bone mineral content and bone mineral density between dominant and nondominant limbs in children 8-16 years of age.

The bone mineral content (BMC), bone mineral density (BMD), and bone free lean tissue (BFLT) of dominant limbs were compared to nondominant values in girls and boys 8-16 years of age (girls, n = 124; boys, n = 110). Results showed that BMC, BMD, and BFLT of the dominant arm was significantly greater than of the nondominant arm (P < .01). The differences were found for both boys and girls and across all age groups except for 8 to 9-year-old boys for BMC. There were no differences in BMC or BMD in the legs, but the dominant leg had significantly greater BFLT than the nondominant leg (P < .01). The greater BMC and BMD values of the dominant arm are likely a result of greater mechanical loading (resulting from normal daily activities) of the dominant arm; this speculation is supported by the greater muscularity in the dominant arm. In the legs it is likely that weight bearing and not bias muscular activity is more important in determining bone mineral status. © 1993 Wiley-Liss, Inc.

Immunoscintigraphic detection of primary and metastatic spontaneous canine osteosarcoma with F(ab')2 fragments of osteosarcoma-associated monoclonal antibody TP-1.

Monoclonal antibody TP-1 has been shown to bind selectively to human and canine osteosarcoma cells in vitro using immunohistochemical stains. This report describes the in vivo administration of radioiodinated F(ab')2 fragments of monoclonal antibody TP-1 in dogs with primary and/or metastatic spontaneous osteosarcoma. Two dogs were injected with 131labeled F(ab')2 TP-1 and two dogs were injected with 123labeled antibody fragments. Immunoscintigraphy successfully demonstrated the radiolabeled antibody fragments in 6/6 known primary or metastatic lesions and in addition detected 4 metastatic lesions not diagnosed by conventional radiographs. Concurrent imaging of 99mTc labeled autologous erythrocytes in two dogs confirmed that the accumulation of radiolabeled antibody fragments was independent of the blood pool. There was no immunoscintigraphic evidence of localization of radioiodine to normal organs or tissues other than those expected to accumulate free iodine. The present study has demonstrated the potential of monoclonal antibody TP-1 F(ab')2 fragments for early detection of metastatic spread of spontaneous osteosarcoma.

Technetium 99m pentavalent dimercaptosuccinic acid and thallium 201 in detecting recurrent medullary carcinoma of the thyroid.

To compare the effectiveness of thallium chloride 201 and technetium 99m pentavalent dimercaptosuccinic acid in evaluating medullary carcinoma of the thyroid (MCT), eight patients with a history of MCT underwent imaging with both radiopharmaceuticals. Thallium 201 consistently gave superior images, as well as providing one less false-negative scan. Positive scans were obtained in patients with elevation of basal calcitonin levels to more than 1,000 ng/L. All of the patients with positive scans had clinical evidence of local recurrence. Improved imaging with thallium 201 was obtained by early scanning.

Immunohistochemical staining and radionuclide imaging of canine tumors, using a monoclonal antibody recognizing a synthetic carbohydrate antigen.

The in vitro and in vivo binding of a monoclonal antibody (MAB) that recognizes a tumor-associated carbohydrate antigen was studied in dogs. Monoclonal antibody 155H.7 was raised in response to innoculation of mice with beta-galactose(1-3)beta N-acetylgalactosamine conjugated to human serum albumin. Avidin-biotin-complex immunohistochemical staining of cryostat sections of normal and neoplastic canine tissue specimens revealed heterogenous binding of MAB 155H.7 to the cells of many canine mammary and lung carcinomas and homogenous staining of many sarcomas, including osteogenic sarcoma. In addition, there was variable staining of a variety of normal tissues including some ductual epithelium, peripheral nerve fibers, and some endothelial cells and fibroblasts. Immunoscintigraphy with 131I-labeled MAB 155H.7 was used to study the in vivo distribution of the antibody. The 131I-labeled MAB 155H.7 was administered to 1 clinically normal dog, 7 dogs with osteogenic sarcoma, 1 dog with undifferentiated sarcoma, and 2 dogs with mammary tumor. Scintigraphy revealed concentration of radioactivity in 8 of 10 tumor sites within 24 hours after MAB administration. The ratio of 131I in tumor sites to 131I in the surrounding normal tissues, compared with the similar ratio of 99mTc-labeled erythrocytes ranged from 1.1 to 4.3, in tumor vs normal tissue with a mean value of 2, confirming tumor localization of the radiolabeled MAB in excess of that associated with enhanced tumor vascularization.

A developmental model for free vascularized bone transfers in the dog.

An autogenous free vascular bone transfer using a segment of ulna along with its periosteum and vascular pedicle was developed. The vascular pedicle, based on the common interosseous artery and vein, emerged where muscular branches from the cranial interosseous artery enter the extensor carpi ulnaris and lateral digital extensor muscles. Four autogenous heterotopic (ulna to tibia) vascular transfers by microvascular anastomosis and two avascular transfers were performed to compare the osteogenic potential and viability of free revascularized grafts with avascular bone grafts. Successful microvascular anastomosis was demonstrated in three of the four vascular transfers by early bone scanning using technetium-labeled polyphosphate. Radiographically, there was more periosteal new bone and callus formation in the successfully revascularized bone transfers than in the failed vascular transfer and the avascular controls. Histologically, viable bone with an intact medullary and periosteal vascular supply was recognized in the grafts successfully revascularized by microvascular anastomosis.

A study of the effects of bipedism and upright posture on the lumbosacral spine and paravertebral muscles of the Wistar rat.

Twenty-one bipedal rats were prepared by forelimb amputation and reared with 19 control rats. All of the bipedal rats became proficient upright walkers. There was significant anterior wedging of the lower lumbar vertebral bodies in all of the bipedal rats and four had radiographic evidence of degenerative disc disease. Five bipedal rats developed lumbosacral disc herniations, and the lumbar neural canal was significantly smaller in the bipedal population. There was no difference in radionuclide uptake between the two groups. Histochemical analysis of the psoas and multifidus muscles showed a significant shift from type I to type II fibers in the psoas and from type II to type I fibers in the multifidus in the bipedal population. These results indicate that upright posture places considerable stress on the lumbosacral spine and paravertebral muscles of the rat.

Measurement of gastric emptying rate in humans by real-time ultrasound.

Simultaneous studies of gastric emptying by ultrasound and scintigraphy were performed in 14 subjects to assess the use of ultrasound for the measurement of gastric emptying rate. The presence of air in the stomach prevented the acquisition of gastric emptying data by ultrasound in 3 of the 14 subjects. In the remaining 11 subjects there was no significant difference between values for the half-time (t1/2) of gastric emptying obtained by scintigraphy [for anterior imaging, mean t1/2 = 20.9 +/- 9.9 min (+/- SD); for anterior and posterior imaging, geometric mean t1/2 = 21.1 +/- 10.5 min (+/- SD)] compared with those derived by ultrasound [mean t1/2 = 20.2 +/- 10.0 min (+/- SD), p greater than 0.05 for each comparison]. A significant correlation between the t1/2 of gastric emptying derived by scintigraphy (anterior scanning and geometric mean of counts obtained by anterior and posterior scanning) and the t1/2 measured by ultrasound was obtained (r2 = 0.7, 0.69, respectively). These results imply that ultrasound can be used for the valid assessment of the gastric emptying rate in humans.