Surrogate markers of visceral adipose tissue in treated HIV-infected patients: accuracy of waist circumference determination.

OBJECTIVES: The accuracy of the use of anthropometrics to quantify visceral adipose tissue (VAT) in treated HIV-infected patients is unknown. We evaluated the predictive accuracy of waist circumference (WC) with and without dual-energy X-ray absorptiometry (DXA)-derived trunk : limb fat ratio [fat mass ratio (FMR)] as surrogates for VAT determined using computerized axial tomography (CT-determined VAT). METHODS: We performed a retrospective cohort analysis of treated HIV-infected male patients followed at the Modena HIV Clinic. We developed prediction equations for VAT using linear regression analysis and Spearman correlations. Receiver operating characteristic (ROC) analysis evaluated the accuracy of WC alone or with FMR at discrete VAT thresholds. RESULTS: The 1500 Caucasian male patients had a median age of 45 years, body mass index (BMI) of 24, WC of 87 cm, VAT area of 127 cm(2) and body fat percentage of 14%. The correlation between WC-predicted VAT and CT-VAT was 0.613, and this increased significantly if FMR was added. The WC-associated R(2) of 0.35 increased to 0.51 if the prediction equation included WC plus FMR. The area under the ROC curve (AUC) using WC was 0.795-0.820 at all VAT thresholds. The positive predictive value (PPV) and negative predictive value (NPV) changed reciprocally at CT-VAT thresholds from 75 to 200 cm(2) and ranged from 0.72 to 0.74, respectively, at a representative VAT of 125 cm(2). Adding the FMR to the predictive equations increased the AUC in the range of 0.854-0.889 with the PPV and NPV increasing minimally, ranging from 0.780 to 0.821. Limits of precision were wide, especially at the highest CT-VAT levels, and varied from 24 to 68 cm(2). CONCLUSIONS: WC is a limited surrogate for CT-VAT in this population and DXA-derived parameters do not improve performance indices to a clinically relevant level. These findings should inform the applicability of WC to predict VAT in treated HIV-infected male patients.

Breast tumor radioimmunodetection with a 111In-labeled monoclonal antibody (MA5) against a mucin-like antigen.

Monoclonal antibody MA5 recognizes a determinant displayed on high molecular weight antigens associated with secretory and malignant breast epithelial cells. MA5 reactivity with greater than 95% of primary and metastatic breast tumors, surface expression of the antigen, as well as its ability to localize within breast tumor xenografts prompted this initial study to determine the efficacy of MA5 to localize breast tumors by radioimmunoscanning. A total of 17 patients was monitored, each receiving 2 mg of purified MA5 labeled with 5 mCi of 111In. Some patients also received 3 or 18 mg of unlabeled carrier antibody (MA5); no serious allergic reactions were noted. Primary tumors, bone lesions, soft tissue recurrences, and lung metastases greater than 3 cm in diameter were detectable, whereas only one lesion (hilar node) less than 3 cm was localized. Significant antibody accumulation was noted in the liver and less significant uptake in the spleen and bone. The extensive fibrosis and poor vascularization of breast tumors may partly explain the limited sensitivity obtained thus far. The imaging results obtained with MA5 are compared with other antibodies which we show recognize the same antigens.

Oral antibiotic therapy of skeletal infections in children.

Oral and intravenous (IV) antibiotic regimens were compared in 15 children with etiologically defined osteomyelitis and/or septic arthritis. On admission all children were started on standard IV therapy; seven were changed to oral antibiotics within 72 hours and the remaining eight continued on IV therapy for four weeks. Oral antibiotic doses were adjusted to achieve a peak serum bactericidal titer of greater than or equal to 1:8 against the patient's own pathogen. All patients were treated in hospital for four weeks; therapy continued for a minimum of six weeks or until the erythrocyte sedimentation rate (ESR) fell below 20 mm/hr. The clinical course and outcome were similar in both groups. There were no treatment failures nor any relapses during a 12-month follow-up period. This prospective study supports, with controlled data, the concept that acute skeletal infections can be safely and successfully treated with carefully monitored oral therapy.

Radiophosphate visualization of the foreign body reaction to wear debris from total knee prosthesis.

Three patients with total knee arthroplasties, in which the tibial and patellar articulating surfaces consisted of a polyethylene-carbon fiber composite, demonstrated technetium-99m methylene diphosphonate (MDP) deposition in the intraarticular space, whereas, the gallium-67 citrate images were normal. This was shown to be due to a synovial giant cell foreign body reaction to particulate carbon fiber debris in one patient who required surgical revision of the prosthesis.

Radiophosphate disclosure of subperiosteal bone formation in renal osteodystrophy.

Subperiosteal bone formation, in contradistinction to resorption, is an unusual occurrence in renal osteodystrophy, and particularly rare in the long bones of the lower extremities according to the radiological literature. Two cases are presented with radiographic and radiophosphate evidence of subperiosteal bone formation in the femora and tibiae, and both showed histologic changes of profound secondary hyperparathyroidism.

Technetium-99m-pyrophosphate kinetics and imaging in metabolic bone disease.

A study was undertaken to investigate the behavior of 99mTc-Sn-pyrophosphate complex in metabolic bone disease. Of clinical importance was the generalized increased periarticular bone accumulation of the radiopharmaceutical in osteomalacia and in combined osteomalacia and osteitis fibrosa as found in patients with chronic renal failure. The pattern in primary hyperparathyroidism was variable. There was no correlation between the initial rates of accumulation of the radiophosphate complex or its bone to soft-tissue uptake ratio at 5 hr when compared with the degree of osteomalacia and osteitis fibrosa. It is postulated that the 99mTc-Sn-pyrophosphate complex has greater affinity for immature collagen than the crystal surface.

Large telangiectatic focal nodular hyperplasia presenting with normal radionuclide studies: case report.

A 9 cm-lesion of telangiectatic focal nodular hyperplasia was incidentally identified in a 31-yr-old female. Despite a typical appearance by X-ray computed tomography and ultrasonography, scintigraphy with technetium-99m-(99mTc) colloid, 99mTc-diethyliminodiacetic acid, and 99mTc-labeled red cells failed to demonstrate any abnormalities. These findings are felt to reflect the relative lack of architectural disruption that histologically characterizes this particular lesion. The present report described the imaging characteristics of the telangiectatic form of focal nodular hyperplasia.

Radiophosphate uptake in asymptomatic knee arthroplasty.

The utility of radiophosphate bone scanning in the detection of complications following total knee replacement (TKR) is not yet fully established. A difficulty associated with the use of bone scanning is the persistent increased uptake seen around the prosthetic joint long after surgery, despite the absence of symptoms. In order to better characterize the time course of radiophosphate uptake, bone scans obtained 1 mo-12 yr after surgery were analyzed in 30 asymptomatic patients with 37 TKR. Uptake was graded 0-4+ in the femoral and tibial components. Scans of 18 implants were obtained 1 yr or less after surgery (Group 1), and 19 were obtained greater than 1 yr after surgery (Group 2). Mean uptake scores were as follows: femoral component Group 1 = 3.0 +/- 1.1; Group 2 = 1.8 +/- 0.9 (p less than 0.05); tibial component Group 1 = 3.2 +/- 0.8; Group 2 = 2.6 +/- 1.1 (not significant). Persistent increased uptake, particularly in the tibial component, reflects mechanical stresses peculiar to knee prostheses, and tends to undermine confidence in diagnosing loosening on the basis of a single study.

Technetium-99m-pyrophosphate bone scans in hyperparathyroidism.

Most patients with primary hyperparathyroidism have normal 5-hr bone-to-soft-tissue ratios for 99MTc-pyrophosphate. In contrast, all five patients with advanced secondary hyperparathyroidism in this study showed significant (p less than 0.001) increases of bone uptake. In the early period after parathyroidectomy, there was no quantitative or qualitative change in uptake. A limited decrease of bone uptake was observed only after prolonged periods of observation. In itself, parathyroid activity seems to have little direct influence on bone uptake of 99MTc-pyrophosphate.

Clinical comparison of 99mTc-labeled preformed phytate colloid and sulfur colloid: concise communication.

An in vitro preformed colloid preparation of 99mTc-Sn-phytate was compared both qualitatively and quantitatively with a commercial 99mTc-sulfur colloid kit in 30 patients. The degree of liver and spleen deposition of radiocolloid was, for practical purposes, the same. A slightly higher background was visually noted in 33% of the patients receiving preformed colloidal 99mTc-Sn-phytate, but it did not interfere with the diagnostic quality of the liver and spleen images. The only advantage of the phytate compound was a preparation time of less than 5 min.

Technetium-99m-pyrophosphate: studies in vivo and in vitro.

In rats with induced rickets, the uptake of 99mTcO4 and 99mTc-pyrophosphate per gram of bone was increased as compared with weight-matched controls. However, the uptake of radioactive calcium and 32P-pyrophosphate was similar in both rachitic and control animals, suggesting that the 99mTc label conferred specificity and favored the rachitic lesions. Employing the rat tibia in an in vitro system, 99mTcO4 uptake was predominantly in the organic bone matrix; radioactive calcium, 32P-pyrophosphate, or 14C-diphosphonate uptake was mainly in the bone mineral; and 99mTc-pyrophosphate, 99mTc-diphosphonate, and 99mTc-polyphosphate were found in both mineral and organic phases. By removal of both mineral and polysaccharide and by using agents that altered the degree of collagen fibril cross-linking, evidence was obtained suggesting the 99mTcO4 and 99mTc-pyrophosphate are preferentially bound by immature collagen.

Quantitative analysis of radiophosphate uptakes in asymptomatic porous-coated hip endoprostheses.

A quantitative analysis of the uptake of radiophosphate adjacent to the femoral component of a porous-coated cementless prosthesis was undertaken in asymptomatic patients in order to establish normal temporal changes. The group consisted of 55 patients with 62 arthroplasties of 1.6-49-mo duration. Ratios of the stem, stem tip, greater trochanter, lesser trochanter and calcar, and normal femur to the reference sacroiliac joint were obtained, as well as tip-to-stem, and stem-to-normal femur in unilateral arthroplasties. The ratios remained stable at 12 months and beyond, except for the tip and lesser trochanter. Tip-to-stem and tip-to-sacroiliac joint ratios decreased by 24% and 33%, respectively, between 12 and 49 mo. There was also a decrease in the relative uptakes at the lesser trochanter and calcar in the same time interval. Evidence is given that different designs of prostheses may not have the same normal temporal uptakes of radiophosphate.

Relationship between bone uptake of 99mTc-pyrophosphate and hydroxyproline in blood and urine.

In a group of hospital patients with various diseases, the urinary hydroxyproline-to-creatinine ratio showed a significant correlation (r = 0.63; p less than 0.001) with the 5-hr bone-to-soft-tissue ratio for 99mTc-pyrophosphate uptake. In patients on chronic hemodialysis, a similar correlation was found between the 5-hr bone-to-soft-tissue ratio and hydroxyproline levels in plasma and serum. The findings suggest that 99mTc-pyrophosphate binding by bone is related to collagen metabolism.

Technetium-99m red blood cell venography in patients with clinically suspected deep vein thrombosis: a prospective study.

We have compared technetium-99m (99mTc) red blood cell (RBC) venography to serial impedance plethysmography (IPG) in 110 consecutive patients with a first episode of clinically suspected deep vein thrombosis (DVT). IPG was performed at Day 0 and, if abnormal, contrast venography was also performed to rule out a falsely positive result. Patients with an initially normal IPG had the test repeated at Days 1, 3, 5 to 7, and 10 to 14. Contrast venography was not performed and anticoagulant treatment was withheld in all patients who remained normal during repeated IPG testing. Technetium-99m RBC venography was performed at Day 0 in patients with an initially abnormal IPG and during the period of serial IPG testing in those with an initially normal IPG. The sensitivity of [99mTc]RBC venography for proximal DVT was 0.68, with 95% confidence limits (CL) from 0.48 to 0.89. Specificity was 0.88 (95% CL from 0.81 to 0.95). When the findings of [99mTc]RBC venography for the entire lower extremity were compared to the reference method, the sensitivity increased to 0.90 (95% CL from 0.82 to 0.97) but the specificity decreased to 0.56 (95% CL from 0.51 to 0.62). Technetium-99m RBC venography is a sensitive but less specific method for detecting DVT of the entire lower extremity. An abnormal [99mTc]RBC venogram, particularly in the calf region, should always be confirmed by another diagnostic method.

Hip and knee prostheses: evaluation of the natural history of periprosthetic bone changes.

This is a review of normal adaptive bone remodeling in response to hip and knee endoprostheses as manifested by changes in regional bone mineral density and radiophosphate uptake as a function of time. The normal evolution of change may vary with the design and composition of the implant. Appreciation of the normal temporal alterations enhances the ability to disclose prosthetic complications, but it is not without its limitations. The literature reports on the efficacy of radiophosphate to detect implant loosening are variable and differ between those that are cemented and not.

Observations on the mechanism of 99mTc-labeled phosphate complex uptake in metabolic bone disease.

This communication describes a series of clinical and animal in vivo and in vitro investigations designed to elucidate the mechanism of 99mTc-Sn-phosphate complex concentration in metabolic bone disease. Rachitic and lathyritic animals were used as experimental models. Based on these studies it is concluded that 99mTc alters the pharmacology of the phosphate complexes, in particular pyrophosphate, which was the test agent most extensively employed, so that the usual affinity for mineral is for the greater part replaced by organic matrix binding. There is also evidence to suggest the immature collagen moiety of the organic matrix is the prime target of 99mTc-Sn-phosphate complex binding. Specifically, the aldehyde groups of the collagen molecule are suspected as being the major site of interaction.

Renal trauma.

Renal injuries are classified as minor, major, and critical/catastrophic for purposes of management. The radionuclide renal scintigram is a safe, simple, and extremely sensitive means of establishing the presence of an injury and monitoring kidney function during conservative management, which is utilized in the vast majority of cases. The information that may be obtained from radionuclide imaging is the state of overall and regional blood transit, overall and regional parenchymal function, and urinary extravasation.

Renal transplant evaluation.

Radionuclide scintigraphy of the renal transplant has assumed an important role in disclosing the complications that beset this life-prolonging procedure. Renal ischemia, whether caused by mechanical obstruction of the blood vessels or ureter or immunological rejection, can be detected by qualitative and quantitative perfusion studies using 99mTc-complexes such as pertechnetate, glucoheptonate and DTPA. Similarly, parenchymal agents such as radiohippurate and 99mTc-DTPA can be quantitated for uptake and their drainage patterns monitored to reveal possible underlying obstructive uropathy and urine extravasation. The literature is replete with mathematical strategems for quantitating perfusion and parenchymal transit of the tracers, but none are truly specific enough to be diagnostic of a given cause of renal ischemia. Serial quantitative radionuclide studies should be obtained during the first 2-3 wk after transplantation with the view of noting an improvement or deterioration of the quantitation parameters as a guage of progress. A deterioration may anticipate biochemical manifestations by 24-48 hr, but it is not specific and must be interpreted in light of the clinical circumstances or necessitate invasive procedures for a definitive diagnosis.

Nuclear medicine techniques in arthritis.

An historical review of radionuclide applications to the assessment of synovitis is presented. Contemporary radiopharmaceuticals are grouped into vascular, bone, and inflammatory markers, and their clinical utility and efficacy in disclosing peripheral synovitis and osteoarthritis are surveyed. There is focus on the debate over the usefulness of quantitative sacroiliac joint measurements for screening sacroiliitis, the significance of the negative peripheral joint scan in patients presenting with polyarthralgia, and the suitability of the joint scan to monitor the response to medical treatment objectively.

A prospective study comparing the clinical examination of peripheral joints with radionuclide scintigraphy in patients with rheumatoid arthritis.

Fifteen patients with classical rheumatoid arthritis were evaluated prospectively on 3 occasions to determine if any additional data could be obtained by joint scintigraphy which was not found by physical examination. Clinical and scan examinations were performed simultaneously and the scans were interpreted qualitatively by a radiologist without knowledge of the clinical findings. Simultaneous evaluations of 86 shoulder, elbow, knee, ankle, 84 wrist, 420 MCP and PIP, and 430 MTP joints were recorded. Concordance was noted in 67% of the evaluations and this was significant for the MCP, PIP, elbow, shoulder, knee, MTP, ankle, but not wrist joints. In 10% of instances the clinical examination was positive when the joint scan was negative. On average, the scan was positive 23% of the time (range 5-44%), when the clinical findings were normal. However, most of these scan abnormalities were due to minimal radionuclide uptake. The scan was most useful in the detection of MTP and ankle abnormalities which had been scored clinically negative, suggesting that greater attention be devoted to the clinical examination of the RA foot by the rheumatologist.