Showing papers in "The Journal of Nuclear Medicine in 1975"

Application of Annihilation Coincidence Detection to Transaxial Reconstruction Tomography

Abstract: A study was carried out to investigate the use of annihilation coincidence detection (ACD) in emmision transaxial reconstruction tomography. The ACD was evaluated in terms of spatial resolution and sensitivity with depth, detection efficiency, effect of pulse-height analysis on resolution and efficiency, correction for attenuation, and cold spot contrast. A prototype positron emission transaxial tomograph (PETT) consisting of a hexagonal array of 24 Nal (Tl) detectors employing ACD was constructed. A fast Fourier transform algorithm was employed to generate the reconstructed image. Computer simulations and phantom and animal studies were carried out to demonstrate that this approach yields tomographic radionuclide images that have high resolution and contrast (hot and cold spot) and that are independent of activity above and below the plane examined. The ACD yields a quantitative nuclear medicine imaging device with high detection efficiency. Comparisons are presented between the ACD and the scintillation camera and scanner. Discussion of the possible applications of the PETT in nuclear medicine is included.

Thallium-201 for Medical Use. I

Abstract: Thallium-201 merits evaluation for myocardial visualization, kidney studies, and tumor diagnosis because of its physical and biologic properties. A method is described for preparation of this radiopharmaceutical for human use. A critical evaluation of 201Tl and other radiopharmaceuticals for myocardial visualization is given.

Technetium-99m-methylene diphosphonate--a superior agent for skeletal imaging: comparison with other technetium complexes.

Abstract: Methylene diphosphonate (MDP) was formulated as a complex of 99mTc for skeletal imaging. This agent was compared with three other bone-seeking technetium agents: ethane-1-hydroxy-1, 1-diphosphonate (EHDP), pyrophosphate, and polyphosphate. In tissue radioassay experiments in rodents, the technetium complexes of MDP and EHDP were similar, but skeletal concentration with both of these agents was higher than that with pyrophosphate or polyphosphate. The total-body retention of MDP and EHDP complexed with 95mTc was studied in beagle dogs for 35 days by excretion measurements and total-body counting and compared with polyphosphate and pertechnetate. The long-term retention was greater for MDP. The 5-day cumulative fecal excretion of 95mTc was low when administered as EHDP or polyphosphate complexes and negligible when administered as MDP complex. In six human volunteers the blood clearance of 99mTc-mdp was similar to that of 18F and significantly faster than that of 99mTc-EHDP. Pyrophosphate cleared from the blood much faster than polyphosphate but slower than the diphosphonates. The urinary excretion of the MDP complex was greater than for EHDP within the first 2-3 hr after injection. The 24-hr urinary excretion of pyrophosphate and polyphosphate complexes was not as complete as for the diphosphonates. All four 99mTc complexes proved satisfactory for clinical imaging studies. The MDP complex produced images of superior quality as early as 2 hr after administration, attributable to its more rapid clearance from the blood and soft tissues. On the contrary, a longer interval of 3-4 hr after injection was usually needed for 99mTc-EHDP; pyrophosphate and polyphosphate complexes regularly required a waiting period of 4 hr. Comparitive radiation dose estimates were made based on the available biologic distribution data for these 99mTc skeletal-localizing agents.

Thallium-201 for medical use. II. Biologic behavior

Abstract: Thallium-201 has been evaluated for myocardial imaging by determining its distribution and assessing its imaging properties. Organ distribution with time was studied in goats, chosen for their large size and easy operability. Myocardial imaging was performed in living and sacrificed goats and also in two anesthetized dogs, without infarction. Infarcts were made by ligature at open chest surgery on the goats and the infarcts subsequently confirmed histologically. The myocardium of normal and infarced, young and old goats was cut into blocks and the isotope distribution measured and compared with that in the lungs, liver, spleen, and kidney in normal goats. The renal medulla-to-cortex concentration ratio in goats was studied and is approximately five. The heart uptake exceeds 3% for 100 min whereas contiguous organs have less than one-half of the myocardial concentration, and blood clearance is rapid. One problem may prove to be inhomogeneity of uptake of thallium in the "normal" myocardium, showing a standard deviation of 1u% in a young goat and 29% in an old goat. In view of the good myocardial uptake, however, this work strongly suggests the trial 201Tl in patients.

High Temporal Resolution ECG-Gated Scintigraphic Angiocardiography

Abstract: 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.

Correlation of neoplasms with incidence and localization of skeletal metastases: An analysis of 1,355 diphosphonate bone scans.

Abstract: A total of 1,355 patients from clinical trails with the 99mTc-labeled bone agent, Osteoscan (99mTc-Sn -EHDP), has shown a higher incidence of skeletal abnormalities than previously reported. Overall in this study, 60% of bone scans were abnormal in patients with nonosseous neoplasms. Carcinoma of breast, lung, and prostate yielded 67%, 64%, and 62% skeletal involvement, respectively. Over 50% of all the skeletal abnormalities for the neoplastic indications were detected in the thorax and vertebra while the skull, pelvis, and extremities accounted for 22%, 38%, and 34%, respectively.

Comparison of 99mTc complexes for renal imaging.

Abstract: The distribution of 17 different agents for renal imaging was compared in the rabbit by organ radioassay at 1 hr. Similarly, 99mTc complexes of iron-ascorbate, glucoheptonate (GHA) and 2,3-dimercaptosuccinic acid (DMS), and 203Hg-chlormerodrin were compared in the dog. The distribution of 99mTc-GHA and DMS was assessed in the human by blood and urinary clearance, external renal measurements, and scintillation camera imaging, and compared with older renal radiopharmaceuticals. Radiation dose estimates, based chiefly on human data, were calculated. Technetium-99m-DMS reaches a high concentration in the renal cortex and its urinary excretion rate and blood clearance are slow. It is excellent for imaging the renal parenchyma without activity in pelvocalyceal collecting system. However, it readily oxidizes and must be used within 30 min of preparation. The biologic distribution of 99mTc-GHA is similar to gluconate and iron-ascorbate complex. Its renal concentration is not as great as that of DMS but its blood and urinary clearances are much faster, resulting in lower radiation doses to most organs. Early camera images with this agent usually demonstrate both the renal parenchyma and collecting system. In later images, ther is excellent demonstration of the parenchyma alone, superior to that obtained with 99mTc-Sn-DTPA. It is a very stable complex and may be used for at least 5 hr after preparation. All radioactive renal agents examined to date have a significant concentration in the liver, making an accurate quantitative comparison between the two kidneys difficult.

Effect of positron range on spatial resolution.

Abstract: The effect of beta+ range on spatial resolution of imaging systems employing the detection of 511-keV annihilation radiation was determined by measuring the variation in the line-spread functions (LSFs) of positron-emitting radionuclides of 64Cu, 11C, and 15O as compared with the 514-keV gamma-ray emitter 85Sr. These radionuclides have maximum beta+ energies of 0.656, 0.960, and 1.72 MeV, respectively. The LSFs were measured in a tissue-equivalent phantom with high-resolution (approximately 2.4 mm FWHM) and low-resolution (approximately 8.8 mm FWHM) straightbore collimators coupled to a NaI(Tl) detector. Theoretical LSFs for the beta+ ranges were also calculated and convolved with the 85Sr LSF to yield the predicted LSFs for 11C and 15O. The high-resolution study showed a 0% and 2.3% increase in the full-width half-maximum (FWHM) and full-width tenth-maximum (FWO.1M) for the low-energy beta+ of 64Cu and a 37% (FWHM) and 52% (FWO.1M) increase for the high energy beta+ of 15O as compared with 85Sr. However, when the system resolution was decreased to 8.8 mm FWHM, the 64Cu showed no change at FWHM or FWO.1M and the 15O showed a 2.3% (FWHM) and 7.8% (FWO.1M) relative to 85Sr. The predicted LSFs were in good agreement with the experimental. These data indicate that the effect of beta+ range on spatial resolution is minimal unless the beta+ energy is larger than or equal to 1.5 MeV and the system resolution is on the order of a few millimeters.

Positron ranges obtained from biomedically important positron-emitting radionuclides.

Abstract: Positron ranges were obtained experimentally for several nuclides used in scintigraphic imaging. The nuclides examined were $sup 11$C, $sup 13$N, $sup 15$O, $sup 18$F, $sup 68$Ga, and $sup 82$Rb. The results are discussed with respect to the ultimate spatial resolution obtained in a scintigraphic image. (auth)

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

Abstract: 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.

Technetium-99m-Pyrophosphate: Studies In vivo and In vitro

Abstract: 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 that 99mTcO4 and 99mTc-pyrophosphate are preferentially bound by immature collagen.

Red cell and plasma volumes in normal adults.

Abstract: Despite numerous published methods for predicting normal red cell and plasma volumes, little is known of the range of normal in subjects of given body dimensions. In this study, reported results of red cell and plasma volumes in 481 normal men and 303 normal women have been used to calculate mean volumes and standard deviations (s.d.) for any given body surface area (male and female results being kept separate). All of these mean volumes, each plus or minus 2 s.d., have been plotted against body surface area. The resulting graphs of means and 95% confidence limits have tended to be curvilinear. Standard deviations have increased with increasing mean volumes, but coefficients of variation (s.d./mean) have shown considerable constancy at 11-12%. The mean values observed in this series have often differed substantially from those predicted from published formulas. Use of the presently observed means with the 11-12% coefficients of variation allows compilation for any surface area of a range of normal against which a clinically obtained volume can be compared.

Clinical assessment of left ventricular regional contraction patterns and ejection fraction by high-resolution gated scintigraphy.

Abstract: An improved, noninvasive, radionuclidic, gated blood-pool imaging technique was developed for clinical analysis of regional contraction abnormalities of the left ventricle and determination of ejection fraction. The principal innovations include high-resolution collimation, higher information density, improved method for dynamic aortic-mitral-diaphragmatic border delineation, accurate selection of the end-systolic gating interval through the use of the phonocardiogram, and accurate end-diastole by on-line gating immediately following the electrocardiographic QRS. The results of scintigraphic studies using /sup 99m/Tc-human serum albumin or /sup 99m/Tc-autologous erythrocytes as tracer were compared with selective radiopaque cineangiographic findings in 27 patients with cardiac disease; excellent correlations of ejection fractions and abnormal contraction patterns were demonstrated. In addition, the clinical usefulness in evaluating ventricular performance was demonstrated in 79 patients with acute and chronic coronary artery disease. (auth)

Analytical study of a high-resolution positron ring detector system for transaxial reconstruction tomography.

Abstract: This paper presents an analytical study of a high-resolution positron ring detector system for transaxial reconstruction tomography. Our goal is a combination of good spatial resolution, high sensitivity, rejection of scattered photons, variable section thickness, and the minimization of the number of photomultipliers and coincidence circuits. A circular ring of 288 NaI(Tl) crystals 0.8 cm wide should provide a resolution of 4 to 7 mm FWHM over a circular region 30 cm in diameter. Coded light pipes permit readout using only 72 photomultipliers and 12 coincidence circuits. With properly designed shielding and an energy resolution of 30 percent FWHM, a positron activity of 200 $mu$Ci per axial centimeter in a 20-cm-diam cylinder of tissue should provide approximately 7,000 events/sec from a 2-cm-thick transaxial section (including a 5 percent accidental coincident background and a 26 percent scattered coincident background). This rate is adequate for both static and dynamic imaging. The device can operate at two to three times higher event rates with increased backgrounds. (auth)

Positron camera with extended counting rate capability.

Abstract: NalProbability of interaction at 510 keVat 150 keV Positron emitters may be imaged using two opposing scintillation cameras without collima tors. The counting rate limitation of this ap proach can be largely overcome by using graded absorbers to reduce scattered radiation from the patient and using not only photopeak events but Compton events in the scintillator as well. This increases the useful counting rate by more than a factor of 5. By combining this technique with the use of fast electronics, useful images have been obtained in the presence of scattering material at counting rates above 7,500 cps.

Enzymatic Inhibition of Diphosphonate: A Proposed Mechanism of Tissue Uptake

Abstract: Enzymes have been proposed as tissue receptors that bind 99mTc-stannous diphosphonate and its analogs. Incubation of diphosphonate with several enzymes demonstrated inhibition of acid and alkaline phosphatase activity but showed no effect on glutamic oxalacetic transaminase and lactate dehydrogenase activity. Complete reversal of the diphosphonate-induced inhibition of alkaline phosphatase activity occurred when calcium ion was added to the reaction. The specificity of calcium to induce reversal was dispelled when magnesium ion gave identical results. Diphosphonate-induced inhibition of acid phosphatase, however, was not reversed by calcium or magnesium.

Radioiodinated fatty acids for heart imaging: iodine monochloride addition compared with iodide replacement labeling.

Abstract: Radioiodinated fatty acids have been proposed as agents for use in heart imaging. Previous studies in experimental animals and humans using 131I-oleic acid of low specific activity were marginally successful. Higher specific activity compounds offer potential improvement for use as imaging agents for normal myocardium. Methods for preparation of high specific activity, radioiodinated fatty acids by iodine monochloride addition to oleic, linoleic, and linolenic acids, and iodide replacement of terminal bromine in 6-bromohexanoic, 11-bromoundecanoic, and 16-bromo-9-hexadecenoic acids are presented and compared. Although both labeling procedures are suitable for use with 123I, the latter synthetic route gives labeled fatty-acid analog molecules and 16-iodo-9-hexadecenoic acid appears to show improved myocardial specificity in preliminary animal studies.

Clinical experience with 99mTc-DMSA (dimercaptosuccinic acid), a new renal-imaging agent.

Abstract: Results are reported from the clinical evaluation of a new radiopharmaceutical for renal imaging, 99mTc-DMSA (dimercaptosuccinic acid). Sixty-five patients were studied and six of these patients' scintiphotos are illustrated. The physical characteristics of 99mTc and the mercurial-like kinetics of the chelate produced high-resolution scintiphotos of the renal parenchyma in patients of all ages and with a variety of disease entities. The commercial availability of the material in kit form permits its usage in all nuclear medicine facilities.

A New and Superior Adrenal Scanning Agent, NP-59

Abstract: The first synthesis of 131I-19-iodocholesterol had a 10-25% radiochemical impurity that was not iodide ion. This impurity has been identified as 6beta-131I-iodomethyl-19-nor cholest 5(10)-en-3beta-ol (NP-59) and has been synthesized. Tissue distribution studies with 131I-NP-59 in rats and dogs revealed a higher adrenal uptake and adrenal-to-tissue ratios compared to 131I-19-iodocholesterol, probably less in vivo deiodination, and superior adrenal images. A high uptake was seen in the adrenal medulla in addition to that in the cortex. Iodine-131-NP-59 is being evaluated for the early detection of adrenal-cortical disorders and as a potential scanning agent for detecting structural abnormalities of the adrenal medulla.

Technetium-99m Labeling by Means of Stannous Pyrophosphate: Application to Bleomycin and Red Blood Cells

Abstract: A new technique of technetium labeling using stannous pyrophosphate instead of stannous chloride as reducing agent for pertechnetate has been applied to red blood cells and bleomycin. Results are so encouraging that this technique could be extended to other compounds capable of forming stable complexes with reduced technetium. No saline washes of red cells are necessary before or after the addition of pertechnetate. No purification step is performed after labeling of bleomycin.

Technetium-99m-pyridoxylideneglutamate: a new hepatobiliary radiopharmaceutical. II. Clinical aspects.

Abstract: Technetium-99m-pyridoxylideneglutamate (99mTc-PG) is a nontoxic radiopharmaceutical that was found to undergo rapid biliary excretion in normal humans. The biliary tree and gallbladder were seen within 10-15 min of injection and by 20 min marked accumulation of radioactivity was noted in the gallbladder and gastrointestinal tract. Of ten "control" volunteers, seven had normal 99mTc-PG-cholescintigrams. In the remaining three, the gallbladder was not visualized. Gallbladder disease was not excluded in these three subjects. Of 24 patients referred for investigation of right upper quadrant abdominal pain, 13 proved to have gallbladder disease. All seven patients with acute cholecystitis and one of four patients with chronic cholecystitis had nonvisualization of the gallbladder on the cholescintigram whereas five patients with chronic cholecystitis or cholesterolosis had normal cholescintigrams. Six of the eight patients with nonvisualization of the gallbladder on cholescintigram had contrast radiologic studies (oral cholecystogram or intravenous cholangiogram or both), and in all six, nonvisualization of the gallbladder was also reported on the contrast study. cholescintigraphy was found to be greatly inferior to contrast radiologic studies in the detection of gallbladder stones. Eleven patients had complete extrahepatic biliary obstruction and this diagnosis was correctly made in all 11 by the cholescintigram. Fourteen patients had incomplete extrahepatic biliary obstruction. The correct diagnosis was made on the cholescintigram in seven but in the remaining seven it was not possible to distinguish between incomplete extrahepatic biliary obstruction and hepatocellular disease. Malignant lesions (carcinomas of head of pancreas, gallbladder, common bile duct or ampulla of Vater) were the cause of obstruction in 10 of the 25 patients with complete or incomplete obstruction and the diagnosis of obstruction due to malignancy was correctly made in 8 of these 10 by means of a scintigraphic equivalent to Courvoisier's sing. Finally, 11 patients had hepatocellular disease and a nonspecific pattern consistent with either imcomplete biliary obstruction or hepatocellular disease was observed on the cholescintigram in all 11. The 99mTc-PG cholescintigram is suggested for a role complementary to that of contrast radiologic studies in the preoperative investigation of patients with possible surgical disease of the biliary tract. Contrast radiologic techniques are advocated as being more appropriate in the nonjaundiced patient with suspected gallbladder disease whereas the 99mTc-PG cholescintigram is advocated as being more appropriate in the patient with jaundice. The value of the 99mTc-PG cholescintigram lies in the confidence with which complete extrahepatic biliary obstruction can be diagnosed. The "scintigraphic Courvoisier's sign" seems a useful indicator of malignant obstruction.

Digital tomographic imaging with time-modulated pseudorandom coded aperture and Anger camera

Abstract: The properties of a time-modulated pseudorandom coded aperture with digital reconstruction are compared with those of conventional collimators used in gamma-ray imaging. The theory of this coded aperture is given and the signal-to-noise ratio in an element of the reconstructed image is shown to depend on the entire source distribution. Experimental results with a preliminary 4 × 4-cm pseudorandom coded aperture and an Anger camera are presented. These results include phantom and human thyroid images and tomographic images of a rat bone scan. The experimental realization of the theoretical advantages of the time-modulated coded aperture gives reason for continuing the clinical implementation and further development of the method.

An evaluation of 99mTc-sulfur colloid liver scintiscans and their usefulness in metastatic workup: a review of 1,424 studies.

Abstract: To determine the clinical usefulness of liver scintiscanning in detecting metastatic disease of the liver, 1,424 liver studies performed on 1,115 patients were reviewed along with their charts. Five hundred eighty-one patients had histopathological evaluation by needle biopsy of the liver, laparotomy, and/or autopsy within a mean period of 40 days of liver scan. The histopatholigical findings were correlated with the liver sicntiscan findings and the latter gave an overall accuracy of 77.3%.

Splenogonadal fusion-a rare congenital anomaly demonstrated by 99tc-sulfur colloid imaging: case report

Abstract: A case report illustrating the value of spleen scanning of an infant in the diagnosis of a rare congenital /sup 99m/Tc-sulfur colloid anomaly characterized by fusion of the spleen and left testis is described. This malformation results from faulty organogenesis during the fifth to the eighth week of fetal development. Only 65 cases have been reported in the world literature. In most instances, the anomaly is recognized as an incidental finding at autopsy or at surgical exploration of the abdomen. In 20 percent of cases the anomaly is associated with osseous malformations such as peromelia, ectromelia, micrognathia, and talipes. (auth)

In vivo distribution of vesicles loaded with radiopharmaceuticals: a study of different routes of administration.

Abstract: The in vivo distribution of vesicles containing radiopharmaceuticals in their cavities has been studied using three routes of administration: intravenous, subcutaneous, and intraperitoneal. The in vivo distribution in mice was determined by dissection of the animals and calculation of radioactivity in the organs. In rats the in vivo distribution was assessed by scintigraphy using a scintillation camera-digital computer unit. After intravenous injection of vesicles, radioactivity is concentrated to some extent in the liver and spleen but the pattern of distribution is different from that of the corresponding free radiopharmaceutical or radiocolloid made of the corresponding radionuclide. The permeability of the vesicular membrane to contained radiopharmaceutical has been shown to vary according to the chemical composition of the vesicles. Vesicles can be used to introduce materials in vivo and the potential exists for their specific targeting by coupling other molecules to their surfaces.

Deadtime characteristics of Anger cameras.

Abstract: The deadtime characterisitcs of Anger cameras are analyzed from theoretical and experimental points of view. An investigation of two Searle Radiographics cameras revealed that they had both paralyzable and nonparalyzable components, the deadtimes of which varied with analyzer window width, the energy of the gamma rays counted, and the position of the "time constant selector" switch in the A-scope module of these cameras. A mathematical model for two-component systems is presented.

Comprehensive evaluation of renal function in the transplanted kidney.

Abstract: By means of a comprehensive renal function test based on the analysis of orthoiodohippurate kinetics carried out 223 times in 86 renal transplant patients, we have been able to separate clearly five clinical entities: normally functioning transplanted kidneys, acute tubular necrosis, cell-mediated rejection, humoral (chronic) rejection, and postrenal obstruction. Accurate prediction of the fate of the rejecting kidney can be made while still subclinical as much as a week before manifestations by other techniques are evident. Data on 22 donors studied 44 times are also presented. The comprehensive test consists of measurements of effective renal plasma flow (ERPF), sequential scintigraphy, calculations of excretory index (EI) (percent dose actually found in bladder and voided urine as a fraction of the percent dose expected at a given time after injection at the patient's specific ERPF), and residual urine volume. Formulas and regression equations for the calculation of ERPF, EI, residual urine, etc., are presented. (auth)