Radionuclide lymphangiography in the evaluation of pediatric patients with lower-extremity edema: concis communication.

The results of 99mTc-sulfur colloid lymphangiography in seven pediatric patients with lower-extremity edema were reviewed. Three scintigraphic patterns were identified: (A) normal uptake in the ilioinguinal nodes bilaterally, found in edema as a result of extrinsic venous obstruction; (B) diffusely increased activity over the involved extremity, with decreased visualization of the ipsilateral ilioinguinal nodes, found in secondary lymphedema; and (c) markedly decreased uptake by the ilioinguinal nodes on the affected side, found in primary (idiopathic) lymphedema. These preliminary results suggest that radionuclide lymphangiography is a useful procedure in the evaluation of pediatric patients with limb swelling.

Diagnostic value of renal imaging incidental to bone scintigraphy with 99mTc-phosphate compounds.

An assessment of the sensitivity and reliability of renal images obtained incidentally to bone scintigraphy with 99mTc-phosphate compounds is reported, and certain patterns of abnormalities associated with those renal images are described. Renal images in 119 bone scintigrams were reviewed and correlated retrospectively with radiographic procedures done within 2 weeks of the bone images. The detection rate for renal abnormalities was 97.4%; the "false-positive" rate was 8.6% and the "false-negative" rate was 2.6%. Abnormal renal images were categorized as (A) nonvisualization of one kidney (13 cases), (B) asymmetric uptake (11 cases), (C) focal decreased uptake (4 cases), (D) bilateral decreased uptake (6 cases), (E) focal increased uptake (4 cases), And (F) miscellaneous (6 cases). The first three categories were always associated with renal abnormalities. Bilaterally decreased uptake and focal increased uptake were not reliable in detecting disease. Extensive metastatic carcinoma of the prostate was noted in three of four patients with bilateral decreased uptake and normal intravenous pyelography. We conclude that renal imaging incidental to bone scintigraphy with phosphate compounds is a valuable diagnostic test. An understanding of the different patterns of abnormalities described should improve the overall reliability of the test.

Quantitative radionuclide imaging for early determination of fate of mandibular bone grafts.

Clinical assessment of bone-graft healing in the maxillofacial region is generally limited to clinical evaluation, radiographs, and biopsy. A noninvasive quantitative radionuclide method has been developed in an animal model, and it seems to allow earlier prediction of graft failure or success than conventional methods. Using a localization technique to identify preselected regions of interest reproducibly in the graft and adjacent host bone, an activity ration was developed between the graft region and a contralateral control. Two mandibular grafting systems were evaluated with this technique. When the activity ratio for the graft region over the period of study approached, or was greater than, the activity ratio for the host bone, the graft subsequently proved successful by clinical observation and gross dissection. When the activity ratio for the host bone remained greater than that of the graft, healing did not occur and the grafts were unsuccessful. This method allowed prediction of graft fate by 6 wk after grafting, and preceded radiographic confirmation of repair or failure by 2-3 wk.

The distribution of the muscarinic acetylcholine receptor antagonists, quinuclidinyl benzilate and quinuclidinyl benzilate methiodide (both tritiated), in rat, guinea pig, and rabbit.

The distribution of [3H]quinuclidinyl benzilate and its methiodide salt was determined in rat, guinea pig, and rabbit. Accumulation in the myocardium of up to 2% of the injected dose per gram of tissue was obtained with both compounds, providing heart-to-blood ratios of approximately 30 and heart-to-lung ratios of approximately 4. The accumulation in the heart was blocked (89%) by preinjection of atropine. The distribution of tritium in rabbit heart corresponds to the muscarinic receptor densities determined in vitro. Calculation of the theoretical maximum for the bound-to-free ratio, based on in-vitro equilibrium binding isotherms, resulted in ratios in reasonable agreement with the experimental results. Because of the high accumulation in the heart with low serum concentration, we conclude that the methiodide salt of quinuclidinyl benzilate represents an ideal parent structure for the design of a receptor-binding gamma-emitting radiopharmaceutical for imaging of the myocardium.

Experimental evaluation of Tc-99m sulfur colloid as a potential imaging agent in thromboembolic disease: concise communication.

Based on literature reports suggesting the possible incorporation of Tc-99m sulfur colloid (Tc-SC) into fibrin deposits, this study was undertaken to evaluate the potential of this radiopharmaceutical as an imaging agent in thromboembolic disease. Animal models of deep-vein thrombosis and pulmonary embolism were used. The mean thrombus-to-blood (T/B) uptake ratios were comparable for fresh and older thrombi (up to 72 hr). Thrombus uptake was significantly lower in a group of five control dogs that received pertechnetate instead of Tc-SC. Intravenous heparin administration (5,000 IU) 2 hr before injection of Tc-SC caused a depression in T/B ratios but did not totally block Tc-SC uptake. Gamma imaging with Tc-SC allowed demonstration of deep-vein thrombi, but imaging of pulmonary emboli as areas of increased activity was not satisfactory. This study supports the concept of thrombus detection with radiolabeled particles but not the extension of this principle to the imaging of pulmonary emboli.

In vivo receptor binding of iodinated beta-adrenoceptor blockers.

Six radiolabeled beta-adrenoceptor blocking agents with a range of affinity constants were evaluated as radioindicators for adrenoceptors in guinea-pig heart and lung. All concentrated in the heart and lung at levels in excess of 0.1% dose/g tissue. On the basis of displacement studies using propranolol, two of the six compounds showed beta-adrenoceptor binding in the lung, and one, H-3 carazolol, showed receptor binding in the heart. These results agree qualitatively with a bi-molecular reversible equilibrium model, and suggest that the beta-adrenoceptor blockers as a group will not be useful in vivo probes of receptor concentration in the heart because of the low affinity constants and high levels of nonreceptor binding associated with the present-day clinical beta blockers. Beta-adrenoceptor blocking agents with affinity constants in excess of 10(9) will be needed to give heart-to-blood ratios of 10.

Gated and cinematic perfusion lung imaging in dogs with experimental pulmonary embolism.

To determine how pulmonary respiratory motion affects detection of pulmonary emboli, 11 dogs had routine lung scans and gated or cinematic perfusion images after undergoing autologous experimental pulmonary embolism. Six dogs had routine six-view perfusion studies, plus end-inspiratory and end-expiratory gated perfusion studies performed with a physiologic synchronizer set to 80% threshold. Five other dogs had three-view ungated and cinematic (post., LPO, RPO) perfusion images. Cinematic studies were acquired by synchronizing a camera-computer system to the Harvard respirator that ventilated the dog. Before death, all animals received i.v. India ink to outline pulmonary perfusion defects, and postmortem lung dissection verified sites of emboli. An ROC curve analysis of randomized perfusion studies showed that end-inspiratory gated images yielded true-positive rates 5--10% higher than ungated images at any given false-positive rate. Lesion detection by cinematic studies was comparable to detection by ungated images, but detection by end-expiratory images was worse. End-inspiratory gated imaging may be useful as an occasional adjunct to routine perfusion lung imaging.

Evolution of acute epididymitis to testicular infarction. Scintigraphic demonstration.

A case of acute epididymitis evolved into testicular infarction. Scrotal scintigraphy identified the initial epididymitis and subsequent evolution into infarction.

Preoperative scintigraphic detection of cervical metastases from thyroid carcinoma with technetium-99m pertechnetate.

A young man with papillary-follicular thyroid carcinoma demonstrated clear visualization of cervical metastases from thyroid cancer on Tc-99m pertechnetate scintigraphy while exhibiting a palpably and scintigraphically normal thyroid gland. This is a very rare occurrence which demonstrates that Tc-99m pertechnetate scintigraphy is capable of detecting cervical metastases from thyroid carcinoma before the appearance of palpable thyroid nodules or defects on scintigraphy.

Extrapulmonary localization of gallium in sarcoidosis.

This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

Gallium-67 localization in herpetic skin lesion.

Previous cases of gallium localization in various cutaneous lesions have been reported, including sporotrichosis, acne vulgaris, sarcoid, lymphoma, and exfoliative erythroderma. This is a report of a case of gallium localization in cutaneous lesions of herpes zoster.

Quantitation of differential renal function with Tc-99m MDP.

This study was designed to evaluate the usefulness of the bone tracer Tc-99m MDP for quantitative assessment of relative renal function as compared with renal imaging radiotracers used for that purpose. Differential renal function, i.e., the percent contribution each kidney makes to global renal function, was determined prospectively in 15 consecutive patients using Tc-99m MDP and a renal radionuclide tracer, either Tc-99m DTPA or Tc-99m GHA. Differential function was computed in all cases from the early (1-3 minutes) renal uptake of the tracers by region-of-interest analysis of the computer-acquired data. There was a high correlation between values of differential function obtained with Tc-99m MDP and those obtained with Tc-99m DTPA or Tc-99m GHA (r = 0.98, P less than 0.0001). Qualitative assessment of the images revealed equivalent scintigraphic patterns in all patients. It is concluded that the early characteristics of renal handling of Tc-MDP are sufficiently similar to those of Tc-DTPA and Tc-GHA so that accurate estimates of differential renal function are possible with this agent, and that Tc-MDP-determined renal differential most likely reflects differential glomerular filtration rate.

Radiogenic changes in the behavior and physiology of the spontaneously hypertensive rat: evidence for a dissociation between acute hypotension and incapacitation.

Immediately following exposure to a sufficiently large dose of ionizing radiation, rats and several other species experience a transient period of acute hypotension and an accompanying deficit in performance. Although significant correlations have been reported between the drop in blood pressure and the early transient incapacitation (ETI) and a causal relationship has been suggested, the extent to which hypotension precipitates the occurrence of the behavioral deficits remains uncertain. The present experiments investigated both radiogenic blood pressure and performance changes in a strain of rat bred for hypertension (spontaneously hypertensive rat: SHR) in order to determine if high blood pressure might attenuate ETI. Although male SHRs experienced a severe ETI and a drop in blood pressure, much of the data is inconsistent with the hypothesis that hypotension causes performance decrements. In an additional series of studies, blood volume and serum chemistry data were analyzed. Male SHRs were significantly higher than normotensive controls on several blood chemistry determinations. Exposure to ionizing radiation, more often than not, enhanced these differences. These results could not be explained on the basis of radiogenic blood volume fluctuations.