Zinc metabolism in humans after oral and intravenous administration of Zn-69m.

Seventeen patients were studied after separate oral and intravenous administration of 50 muCi Zn-69m to determine if Zn-69m is suitable for studying zinc metabolism in humans and to determine if the route of administration affects kinetics. Patients stayed on a metabolic ward for each study. Activity was measured in the total body, urine, feces, blood, plasma, red blood cells, and by detectors over liver and thigh. Five day urine to fecal ratios were 0.44 (intravenous), 0.018 (oral). Most activity went rapidly to liver, then followed two component exponential loss patterns in both cases. Thigh area doubling time was 5.7 days whether the zinc was given orally or intravenously. Plasma activity decreased to less than 2% of that injected by 24 hr after intravenous administration and decreased from a maximum of 1.2% of that ingested, 3 hr after oral administration to 0.7% by 24 hr. Red blood cell activity increased through the 5-day study period to maximum values of 6.4% of that injected after intravenous administration and 2.4% of that ingested after oral administration. Similar metabolic patterns were observed regardless of whether Zn-69m was administered intravenously or orally, suggesting that these patterns were not affected by the mode of administration for the cases studied.

Absorption of orally administered 65Zn by normal human subjects.

Despite studies by several investigators of human gastrointestinal 65Zn absorption, implications of these data for evaluation of functional zinc status are unclear because limited numbers of normal subjects have been studied. To evaluated zinc absorption in normal humans, 75 subjects (31 women, 44 men, ages 18 to 84 yr) were given 10 micro Ci carrier-free 65Zn orally after an overnight fast. Absorption calculated from total body retention measured 7, 14, and 21 days after administration of tracer was 65 +/- 11% (mean +/- 1 SD), range from 40 to 86%. Comparison of these results with those for patients with a variety of diseases indicate that patients exhibit a wider range of absorption and, in four of six studies patients exhibit decreased mean zinc absorption. These results of gastrointestinal zinc absorption in a large number of normal humans offer a basis for a clearer comparison with data from patients who exhibit abnormalities of zinc absorption.

Kinky hair disease. Study of copper metabolism with use of 67Cu.

Metabolism of labeled Cu (67Cu) was studied in three patients with kinky hair disease (KHD). Labeled Cu was administered first intravenously and, later, orally. We determined oral absorption, excretion, and internal kinetics of this metal. Patients with KHD absorbed 11% to 13% of Cu given orally, compared to 46% by unaffected controls. Total excretion of Cu given intravenously during the first seven days after administration was greatly reduced in patients with KHD. The biological half-life of 67Cu in patients with KHD was increased by a factor of 2 to 3 over the normal control. Most of the labeled Cu was retained by the patient's liver, while in the control subject there was more rapid movement to the Cu to circulation (ceruloplasmin). Red blood cells of patients with KHD incorporated orally administered Cu preferentially, which was sufficient to prevent anemia.

Glucose utilization of cerebral gliomas measured by [18F] fluorodeoxyglucose and positron emission tomography.

Positron emission tomography was used to measure local cerebral glucose utilization by the 1-[18F]fluoro-2-deoxy-D-glucose technique in 23 patients with cerebral gliomas. All 10 high-grade (III and IV) astrocytomas demonstrated a region of high activity with a glucose consumption of 7.4 +/- 3.5 (SD) mg/100 gm per minute. The 13 low-grade (I and II) gliomas had a glucose metabolic rate of 4.0 +/- 1.8 mg/100 gm per minute, with no distinctly visible hot spot. Thus, we found a correlation between rate of glycolysis and malignancy in primary cerebral tumors. Cerebral cortical glucose utilization was often depressed in areas adjacent to or neurally connected to the tumor site, and there was focal irregular delta wave EEG activity in these areas.

Gallium-67 scanning: limited usefulness in staging patients with non-Hodgkin's lymphoma.

The records of 122 patients with non-Hodgkin's lymphoma were reviewed, and the findings of the gallium scan analyzed. The scans of 93 patients were reread without knowledge of the previous readings. Two nuclear medicine physicians agreed with the original readings in 70 per cent of the cases and with each other in 89 per cent of the cases. When the data are analyzed case by case, 52 per cent true positive, 13 per cent false positive and 34 per cent false negative scans were found with only 17 per cent of the scans locating disease not found by routine physical examination and roentgenograms. Looking at individual sites of disease, the gallium scan yields an over-all detection of diseased sites of 18.5 per cent, with 72 per cent of all sites being correctly classified as positive or negative. The diffuse histiocytic, mixed and undifferentiated histologies were detected more accurately than all others, with mediastinal and extranodal sites being identified more frequently than any nodal site. The gallium scan revealed a site of disease which advanced the clinical stage in only one of 122 patients (upstaged). Only one of 122 patients was upstaged as a result of gallium scanning. These data suggest that gallium scanning may not be cost effective in the routine staging of patients with non-Hodgkin's lymphoma.

Radioiodine therapy for thyroid cancer.

A small abut important subset of patients with differentiated thyroid cancer will die of disease. Our approach to therapy treats almost all patients similarly, with aggressive surgery and I-131 therapy. Meticulous follow-up should include multiple I-131 diagnostic scans using at least 5 to 10 mCi of I-131 with attention to proper patient preparation and good quality procedures. Thyroglobulin levels should be monitored, and other radiographic diagnostic procedures, including thallium scans and MR imaging, should be used as needed. Until screening tests are discovered which will accurately pinpoint patients at high risk for aggressive, recurrent thyroid cancer, the best course of action appears to be aggressive management, including radioiodine therapy.

Scintigraphic detection of occult hemorrhage in a patient receiving anticoagulants.

The exact location of hemorrhage complicating anticoagulant therapy is sometimes difficult to establish. We present a case in which imaging with 99mTc-labeled red cells had a significant role in the diagnosis of soft-tissue bleeding in a paraplegic patient receiving long-term anticoagulation.

Right-to-left shunting via persistent left superior vena cava identified by perfusion lung scintigraphy.

A right-to-left shunt was demonstrated following a left antecubital injection of [99mTc]MAA but was not seen after a right antecubital injection. This was because of the presence of a persistent left superior vena cava draining into the left atrium. Recognition of the presence of this anatomic variant is of importance in perfusion imaging, in patients with otherwise unexplained systemic embolization.

A nuclear medical manifestation of Munchausen's syndrome.

A man with an enlarged and tender left calf, chest pain, intermittant hemoptysis, and shortness of breath was referred for a lung scan. Positioning for the ventilation part of the study revealed a high level of radioactivity in the lungs, kidneys, bladder, colon, and salivary glands. The patient denied previous hospital studies and suggested that he may have become contaminated while transporting radioactive materials as an independent truck driver. He was found to be a classic example of Munchausen's syndrome.

Radiometric estimation of the replication time of bacteria in culture: an objective and precise approach to quantitative microbiology.

In a recently developed, two-compartment liquid scintillation vial, the evolution of 14CO2 resulting from bacterial metabolism of uniformly labeled d-glucose was measured sensitively, cumulatively, and automatically in a liquid-scintillation counter. In each of eight species tested, a period of log-linear expansion of cumulative counting rate with time was observed. The exponential increase in cumulative counting rate was related to cell replication time by the integral of a first-order differential equation. Within a given species, the replication time measured by radioassay was found to be remarkably constant, unaffected by a fourfold variation in the activity of added labeled d-glucose, insensitive to the presence of carrier dextrose, and independent of the number of bacteria in the initial inoculum over a range of five orders of magnitude. These experiments demonstrate that the replication rate of an organism in culture is a highly reproducible characteristic that is susceptible to precise radiometric measurement in fundamental units of time under a variety of experimental conditions.

A method for objective evaluation of functional images.

A method is described for characterizing functional maps by means of a frequency distribution function (DF) of pixels. The method makes use of a map of the standard deviation of the functional parameter. By use of this map the method (a) becomes less sensitive to imprecise definition of the organ borders, (b) compensates for random fluctuations in the functional map, and (most importantly) (c) permits spatial information to be included in the DF. This spatial information is included by performing spatial cluster weighting--a procedure that emphasizes regional dysfunction over global dysfunction. The method is illustrated by applying it to phase maps of the left ventricle. In this example, it is shown that analysis of the DF permits detection of regional abnormalities of LV wall motion and that an improvement in detectability is obtained with cluster weighting.

Arteriographically confirmed focal defect in colloid spleen scan with no gross pathologic lession: case report.

A focal avascular defect in an enlarged spleen, clearly shown both by 99mTc-sulfur colloid scanning and by celiac angiography, could not be associated with any gross pathologic abnormality at splenectomy. Vascular lesions can probably produce focal defects on the scan in the absence of infarction.

Accidental ingestion of Tc-99m in breast milk by a 10-week-old child.

Ten weeks after the birth of her first child by Caesarian section, a 27-year-old woman was admitted for evaluation of a possible central nervous system lesion. Four hours after i.v. administration of 15 mCi of Tc-99m for a brain scan, the patient breast-fed her infant; then became concerned about the possibility of radioactivity in her breast milk. Total body gamma-ray measurements of the infant indicated ingestion of 82.5 muCi Tc-99m (corrected for effective T 1/2), while ingestion calculated from gamma-ray measurements of serial milk samples was 75.6 muCi. The single organ radiation dose for the thyroid as the critical organ was 300 mRad, whereas that to the total body was 12 mRad (values derived from 82.5 muCi determined by whole body counting). Had breast feeding been continued at 4-hr intervals, the total ingested activity would have been 94.8 muCi giving the infant a dose of 380 mRad to the thyroid and 16 mRad to the whole body. Had the feeding been given 1/2-hr after injection 726 muCi would have been ingested, increasing the dose by a factor of 10.

Left-ventricular peak ejection rate, filling rate, and ejection fraction--frame rate requirements at rest and exercise: concise communication.

The effect of framing rate on the measurement of left-ventricular (LV) ejection fraction (EF), peak ejection rate (PER), and peak filling rate (PFR) was evaluated at rest and during exercise in 11 normal subjects and 21 patients who underwent gated equilibrium blood-pool imaging. Left-ventricular time-activity curves were obtained in each subject, at rest and during stress, at temporal resolutions of 10, 20, 30, 40, and 50 msec per frame. Ejection fraction, PER, and PFR were determined for each frame duration. By observing changes in the measured values of these quantities with framing rate we conclude that: a) for the measurement of EF, 50 msec per frame at rest and 40 msec per frame at exercise is sufficient; b) PER requires 40 msec per frame at rest and 20 msec per frame during exercise; and c) for the measurement of PFR, at least 40 msec per frame at rest and 20 msec per frame during exercise are needed. These results should hold for both first-pass and gated equilibrium studies.

Gallium-67 citrate imaging in Hodgkin's disease: final report of cooperative group.

A large cooperative study of Ga-67 uptake in Hodgkin's disease showed that 88% of untreated patients had a positive uptake in one or more lesions. The percent of individual lesions seen on scan, however, was significantly lower; this indicated that negative findings at any one site do not argue strongly against the possiblilty of a lesion there. After treatment, the number of visualized lesions decreased sharply, but the exact role of Ga-67 in evaluating therapy is still not clear. Of the various histologic types of Hodgkin's disease, there was a high incidence of localization in all except the lymphocyte-predominance type, which showed a slightly lower uptake. No lesions less than 1 cm in diameter were successfully imaged and the size most easily detected was 4 cm in diameter. As expected, the imaging technique was much less successful for abdominal lesions than for those at other sites because of interfering concentration in bowel and liver. Both radiotherpy and chemotherapy tend to reverse the abnormalities seen on scan. The finding of a significant number of unsuspected positive lesions in asymptomatic patients returning for routine followup suggests that this is a distinctly valuable use of Ga-67, allowing early therpy for recurrences.

Usefulness of gallium scintigraphy in primary and metastatic breast carcinoma.

Gallium-67-citrate whole-body scintigraphy was incorporated into the evaluation of 125 patients with primary and metastatic breast carcinoma. A prospective analysis of these patients demonstrated gallium scanning to be limited in its corroborative value and of practical use only in detecting metastatic breast carcinoma in the mediastinum. Since the extent of tumor involvement is a significant prognostic factor, the gallium scan merits consideration for the detection of mediastinal metastases.

High temporal resolution ECG-gated scintigraphic angiocardiography.

The cardiac blood pool is visualized with high temporal resolution during a complete, average, cardiac cycle. The technique yields both qualitative and quantitative measures of cardiac performance.

Radionuclide cinepneumography: flow-volume imaging of the respiratory cycle.

A procedure is described that generates a series of images spanning an average respiratory cycle. Images are constructed from scintigraphic data with similar respiratory flow and volume characteristics so that they may be displayed in continuous-loop movie format. This technique is noninvasive and requires little patient cooperation or technologist time. It should be most useful in investigations of dynamic pulmonary function, but may be applied to any radionuclide study affected by respiratory motion.

Beat-by-beat validation of ECG gating.

Ejection fraction, normalized peak ejection and filling rates, and the time of occurrence of these events relative to the R-wave were determined in each of 512 consecutive individual cardiac cycles in each of 30 patients using an ultra-high-efficiency nonimaging detector system. For a given patient the 512 measurements of each quantity were averaged and compared with the value of this same quantity as determined from an R-wave-gated left-ventricular (LV) time-activity curve (TAC) derived from the same 512 cycles. We conclude (a) that a small but detectable systematic underestimate occurs in some LV function parameters when they are derived from gated LV TACs; (b) that the magnitude of this underestimate is smaller and less variable for systolic than for diastolic measurements; (c) that the magnitude of the underestimate is not greater than 20% in any single patient for diastolic parameters, nor greater than 8% in any individual patient for systolic parameters, and is substantially less for most patients; and (d) that a small subset of patients may require beat-length windowing if the gated values of diastolic parameters are to fall within these limits. Thus LV function measurements obtained from gated TACs adequately reflect the true average of such values during the measurement interval.

Measurement of ventricular function by ECG gating during atrial fibrillation.

The assumptions necessary to perform ECG-gated cardiac studies are seemingly not valid for patients in atrial fibrillation (AF). To evaluate the effect of AF on equilibrium gated scintigraphy, beat-by-beat measurements of left-ventricular function were made on seven subjects in AF (mean heart rate 64 bpm), using a high-efficiency nonimaging detector. The parameters evaluated were ejection fraction (EF), time to end-systole (TES), peak rates of ejection and filling (PER,PFR), and their times of occurrence (TPER,TPFR). By averaging together single-beat values of EF, PER, etc., it was possible to determine the true mean values of these parameters. The single-beat mean values were compared with the corresponding parameters calculated from one ECG-gated time-activity curve (TAC) obtained by superimposing all the single-beat TACs irrespective of their length. For this population with slow heart rates, we find that the values for EF, etc., produced from ECG-gated time-activity curves, are very similar to those obtained from the single-beat data. Thus use of ECG gating at low heart rates may allow reliable estimation of average cardiac function even in subjects with AF.