Technetium-99m pyrophosphate scintigraphy for the detection of acute myocardial infarction. How useful is it?

To evaluate the contribution of Tc-99m pyrophosphate scintigraphy (TPS) on the overall management of patients suspected of having acute myocardial infarction (AMI), hospital records of 58 consecutive patients who underwent TPS, were evaluated in depth. The results indicate that TPS was essential for the diagnosis of AMI in 16% of the patients. TPS was most rewarding in perioperative patients and in patients with borderline or uninterpretable electrocardiographic and enzyme changes. Also, in some cases, TPS was able to confirm or exclude the diagnosis of AMI prior to the confirmation by serial electrocardiograms (ECG) and serial enzyme changes. TPS was less rewarding in patients with clinically low index of suspicion for AMI. It may also be confusing in patients with high clinical likelihood of AMI and a history of prior myocardial infarction because of the possibility of persistently positive TPS in some of these patients. Considering the limitations of ECGs, the cardiac enzymes, and atypical clinical presentations in the patient population we evaluated, TPS appears to be fairly accurate when the scintigraphic findings are compared with the final diagnosis at the time of discharge from the hospital.

Biological nature of the effect of ascorbic acids on the growth of human leukemic cells

The effects of L-ascorbic acid (LAA) on the in vitro growth of human leukemic colony-forming cells (L-CFC) were analyzed for all acute nonlymphocytic leukemia patients from whom bone marrow aspirates were received by this laboratory for cell culture study. Among 259 cases, 163 could be directly evaluated for LAA effect. L-CFC growth enhancement was noted in 53 (33%) and suppression in 28 (17%), with overall 50% of patients affected by LAA. Among 34 normal bone marrows tested, none were enhanced by LAA while 8 (24%) were suppressed. While caution is needed in interpreting L-CFC suppression by LAA, L-CFC enhancement is clearly significant. Two isomers of LAA, D-isoascorbic acid and D-ascorbic acid, which have weaker antiscorbutic activity than that of LAA, also produced the L-CFC growth-enhancing effect, but to a lesser degree than that of LAA. A dose-response study also substantiated that D-ascorbic acid was definitely less effective than was LAA. Since D-ascorbic acid is the true optical isomer of LAA and has identical physicochemical properties as does LAA, this differential effect is clearly of biological nature. This study indicates that L-CFC growth suppression by LAA is observed in one-sixth of leukemic patients, L-CFC enhancement in one-third of patients, and that L-CFC growth enhancement is a clearly significant finding with a biological mechanism as the basis.

"Streaming" in portal vein. Its effect on the spread of metastases to the liver

Fifty-five consecutive patients with colorectal carcinoma and hepatic metastases on the Tc-99m sulfur colloid liver/spleen scan (TSC) were evaluated to see if the pattern of spread of colorectal metastases was affected by the venous drainage of the primary site. The results suggest that significant streaming probably exists in the portal vein and the spread of metastases to the liver is affected by it. This information has a potential clinical implication in terms of diagnostic workup and chemotherapeutic infusions. It also supports the speculation that a streaming effect exists in humans.

Co-existent parathyroid adenoma and thyroid carcinoma. Nonspecificity of dual tracer parathyroid imaging for parathyroid lesions

Dual tracer parathyroid imaging (DTPI) using Tc-99m and TI-201 has a reported sensitivity of 92% for the detection of parathyroid adenomas. A patient with biopsy-proven parathyroid adenoma as well as papillary thyroid carcinoma is presented. To date, this is the first such case ever to be reported and implies that DTPI, although a sensitive diagnostic modality for parathyroid adenoma detection, is not specific. The diagnosis of primary hyperparathyroidism has recently been established more frequently than in the past due to detection of elevated serum calcium levels on routine blood samples, relatively sensitive parathormone (PTH) assays, and noninvasive imaging modalities such as nuclear medicine, CT scanning, and ultrasonography. At our institution, we have successfully detected the location of parathyroid adenomas in many cases, using the dual tracer method with TI-201 and Tc-99m, confirmed at surgery. We present a case of primary hyperparathyroidism in which two distinct lesions were detected by nuclear imaging: one lesion was proven at surgery to be a parathyroid adenoma, while the other represented thyroid carcinoma.

The use of scintigraphic studies in mid-ventricular obstructive cardiomyopathy to rule out pseudoaneurysm

A "pseudo-pseudo" aneurysm of the left ventricle due to mid-ventricular obstruction from asymmetric septal hypertrophy is presented. A case of mid-ventricular hypertrophic obstructive cardiomyopathy (MVHOCM) was evaluated by means of echocardiography, angiocardiography, gated cardiac blood pool scanning, and a TI-201 myocardial scan. The gated cardiac blood pool scan appearance of MVHOCM is similar to pseudoaneurysm of the left ventricle. TI-201 myocardial imaging, however, was able to distinguish between MVHOCM and pseudoaneurysm of the left ventricle.

Cytophagic histiocytic panniculitis. A variant of malignant histiocytosis

This report describes a patient with cytophagic histiocytic panniculitis in which the aggressive use of chemotherapeutic agents resulted in an apparent remission. The histiocytic nature of the process was confirmed by immunohistochemical techniques. There are many similarities with malignant histiocytosis, and it is believed that this entity should be regarded as a variant of malignant histiocytosis.

Iofetamine HCl I-123 (Iodoamphetamine) brain SPECT atlas

SPECT brain imaging using Iofetamine HC1 I-123 (IMP) has a great potential in the evaluation of various neurologic disorders. Transverse, coronal, and sagittal sectional IMP images obtained using a single head rotating gamma camera system are correlated with corresponding normal brain slices in this atlas.

Evaluation of indium-111-2-mercaptopyridine-N-oxide for labeling leukocytes in plasma: a kit preparation

Pure neutrophils, lymphocytes, and mixed leukocytes have been labeled in vitro with 111ln chelated to a nontoxic, water soluble agent 2-mercaptopyridine-N-oxide (Merc). Cells were labeled in isotonic salt-balanced medium with preformed [111ln] Merc (yield greater than 95%), or in 0.5 ml autologous plasma by incubation with dry Merc first and then with 111ln (yield 75%). The latter method facilitated a kit procedure that required 2 micrograms dry Merc when acid citrate dextrose was used as anticoagulant or 20 micrograms when heparin was used. Labeling efficiency was dependent on cell concentration and pH. Labeled cells accumulated avidly in experimental abscesses and provided abscess/blood ratios of greater than 75 at 24 hr postinjection. In dogs, the liver uptake of labeled cells was only 18.8 +/- 7.1% compared to that of 48.5% when cells were labeled with [111ln]oxine.

Simplified and efficient labeling of human platelets in plasma using indium-111-2-mercaptopyridine-N-oxide: preparation and evaluation

The need for a gamma-emitting radioactive agent that will label platelets in plasma efficiently by a procedure that can be used uniformly in each laboratory is well recognized. A water soluble sodium salt of 2-Mercaptopyridine-N-oxide (Merc) was evaluated that quantitatively chelated 111ln at a pH range of 0.7 to 7.4, and allowed greater than 80% incorporation of 111ln in platelets in plasma. This was dependent on pH, Merc concentration, and platelet concentration. Platelets were labeled using either preformed [111ln]Merc or incubating platelets with 2.5 micrograms dry Merc first and then with 111ln. The latter method provided a simple kit procedure that labeled platelets with negligible alteration of in vitro aggregability. In dogs, labeled platelets had normal survival (7.5 days), 66 +/- 6.6% recovery, detected vascular thrombi (thrombi/blood = 59.4), and pulmonary emboli (PE/blood = 46.2) by scintigraphy. In the kit procedure, the use of Merc compared favorably to that of oxine and tropolone.

Radiation response of human normal and leukemic hemopoietic cells assayed by in vitro colony formation

The effect of ionizing radiation on the survival of bone marrow cells from patients with acute nonlymphocytic leukemia or from hematologically normal controls was studied using colony formation as an endpoint. A modified agar culture method which incorporated daily feeding with new medium was used to allow the growth of leukemic cell colonies. Analysis of radiation-dose survival curves revealed that normal bone marrow cell populations exhibited a relatively steep slope, with values of D0 ranging from 0.5-1.3 Gy (mean = 0.82 +/- 0.22 Gy). There was essentially no shoulder to the survival curves, with Dq values ranging from less than 0 to 0.3 Gy. The leukemic cells tested displayed survival curves that did not differ qualitatively from those obtained with normal cells, i.e., steep slopes and neglible shoulders. However, the average value of the D0 (0.62 +/- 0.15 Gy) was statistically different (p less than 0.025) than that obtained for the normal cells. The results of these studies may have implications both for the use of radiation therapy for the treatment of malignant hemopoietic diseases, and for total body irradiation prior to bone marrow transplantation.

Enhancement of SPECT images by Fourier filtering the projection image set

Tomographic images from rotating gamma camera systems are often difficult to interpret because of poor contrast and high noise levels. A method is presented for improving the quality of these images by Fourier filtering the projection image set prior to reconstruction. A two-dimensional circularly symmetric Gaussian function is used as the spatial frequency filter. This filter can be optimized to enhance contrast and suppress noise in the projection image set in a straightforward and simple manner from the power spectra of representative projections. Preprocessing of the projections makes it possible to use a ramp reconstruction filter. The resulting tomographic sections show a dramatic improvement in image quality.

The perisplenic halo of Ga-67 citrate. A sign of perisplenic abscess

Two cases are presented which display a scintigraphic picture of increased Ga-67 activity around the spleen with a relative photon deficient center. We call this pattern the perisplenic halo of Ga-67, which represents a perisplenic abscess. The anatomy of the perisplenic compartment and the possible pitfalls in diagnosing the perisplenic halo are discussed within the paper.

Noninvasive diagnosis and follow-up of childhood renal vein thrombosis by ultrasound, Doppler, and renal scintiscan

Childhood renal vein thrombosis (RVT) usually occurs in infants less than one year of age, and in recent years, more RVTs are diagnosed with the help of various diagnostic imaging modalities. RVT produces immediate physiologic, anatomic, and functional changes within the involved kidney or kidneys and these changes can be detected readily and noninvasively by Doppler ultrasound, ultrasound scan, and renal scintiscans. Childhood RVTs are associated with substantial morbidity, and the earlier the diagnosis and treatment, the better the prognosis. The most important factor in the diagnosis of childhood RVT is a high clinical index of suspicion. With a high degree of clinical suspicion, one can make the specific diagnosis of RVT using the noninvasive methods. Such methods can also be used for follow-up of patients with RVTs.

Contribution of radionuclide imaging to radiation oncology

Radionuclide imaging has been helpful to oncologists in the initial evaluation and follow-up of patients with primary and metastatic disease. With the introduction of ultrasound and computed tomography, there has been some reduction in the number of radionuclide imaging procedures. These imaging modalities should be used to complement one another. With the introduction of single-photon emission computed tomography in clinical nuclear medicine, there will be a significant improvement in the sensitivity, accuracy, and quantitative ability to detect abnormal lesions. There are intensive efforts in the development of tumor imaging using new agents. Specific antibodies for surface tumor antigens can be labeled with radioisotopes and used as tools for screening primary tumors and metastatic lesions. Therefore, for the present, radionuclide imaging will continue to contribute to clinical oncology.

Rapid detection of insignificant bacteriuria by concomitant use of Lumac system and Gram's stain

The Lumac system, which assays bacterial ATP by bioluminescence, is a rapid method (less than 1 hour) for detection of bacteriuria. Conventional culture by calibrated loop technic and the Lumac system were compared using 2,000 urine specimens. Interpretation of Gram's stains of uncentrifuged specimens in addition to results of the Lumac system provided a second comparison with culture. Using a criterion of greater than or equal to 10(4) CFU/mL, conventional culture yielded 17% of the 2,000 specimens positive for bacteriuria. By Lumac + smear 27% were positive opposed to 41% positive by the Lumac system alone. The Lumac + smear method produced sensitivity (97%), specificity (88%), positive predictive value (62%), and negative predictive value (99.3%). False negative rates by the Lumac alone and Lumac + smear were 0.65% and 0.5%, respectively.

Hepatic steatosis in rats fed diets with varying concentrations of sucrose

The role of dietary sucrose concentrations in the development of hepatic steatosis in rats was investigated. Twelve groups of weanling male Sprague-Dawley rats received semipurified diets with different sucrose concentrations ranging from 20 to 50% (w/w); one group received a cereal-based chow diet. Rats were sacrificed after 3 weeks and body weight, liver/body weight ratio, plasma alanine aminotransferase concentration, hepatic triglyceride concentration, and liver morphology (light and electron microscopy) were determined. Body weight and liver/body weight ratio were decreased in rats receiving 40-50 or 25-35% dietary sucrose compared to rats receiving 20% sucrose or chow. Plasma alanine aminotransferase concentrations were within normal limits. Hepatic triglyceride concentration was significantly increased in rats receiving 40-50 and 25-35% dietary sucrose compared to rats receiving 20% dietary sucrose or chow. Light microscopy showed hepatic steatosis in a periportal distribution at all concentrations of dietary sucrose. Both the frequency and the severity of the steatosis were increased with increasing dietary sucrose concentrations. Electron microscopy from selected livers with increased hepatic triglyceride concentrations revealed increased lipid spheres and increased smooth endoplasmic reticulum without prominent Golgi apparatus or GERL complex. It is concluded that high dietary sucrose concentrations are responsible for the development of hepatic steatosis. Semipurified diets with high dietary sucrose concentrations such as the AIN-76A diet (50% sucrose) should not be used in animal studies in which increased triglyceride deposition could influence experimental outcome.

Hypertrophied moderator band in atrial septal defect

A case of hypertrophied "moderator band" due to atrial septal defect is demonstrated on a resting thallium myocardial scan and a gated blood pool scan.

Characteristics of 3H-substance P binding sites in rat brain membranes

Binding characteristics of 3H-Substance P (SP) were studied with rat brain membranes using a method applied to peripheral tissues by Lee and Snyder [15]. This method was well applicable to central nervous system (CNS) tissues. The results in the present study indicate that specific 3H-SP binding reaches a plateau only after 20 minutes of incubation, and the binding sites are saturable at a relatively low concentration of 3H-SP. Scatchard analysis of specific binding data reveals a single class of binding sites with a high affinity (Kd = 0.30 nM) and a low density (Bmax = 27.7 fmol/mg protein) in rat brain membranes. A Hill plot of the displacement curve of 3H-SP with unlabelled SP showed no indication for cooperativity (nH = 0.83). The relative potencies of binding of various SP fragments at 3H-SP binding sites were fairly parallel to the length of the C-terminal fragments. Neurotransmitters not structurally related to SP produced no effect on 3H-SP binding even when used at micromolar concentrations.

Preferential growth inhibition of human leukemic versus normal myeloid colony-forming cells by 12-O-tetradecanoylphorbol-13-acetate

Myeloid leukemic cells can be induced to differentiate by various compounds, suggesting the possibility of controlling leukemia through induced differentiation. For this to be feasible, the growth of leukemic progenitor cells should be inhibited by these compounds, with the inhibition preferentially affecting leukemic over normal hemopoietic progenitor cells. 12-O-Tetradecanoylphorbol-13-acetate (TPA) was chosen as a differentiation inducer and was studied for its effect on the growth of leukemic colony-forming cells (L-CFU) in ten patients with acute nonlymphocytic leukemia in comparison with normal myeloid colony-forming cells (CFU-C). Growth inhibition of both L-CFU and CFU-C was observed with TPA concentrations as low as 10(-10) M. With increasing concentrations of TPA, survival of L-CFU tended to decline more precipitously than that of CFU-C. In eight of ten patients, inhibition of L-CFU was significantly greater (P less than 0.01) than CFU-C with TPA concentrations of 10(-9) M or higher. This study indicates that a compound capable of inducing differentiation of leukemic cells can inhibit growth of leukemic progenitor cells and that this growth inhibition applies preferentially to leukemic cells as compared with normal hemopoietic cells.

Preparation and evaluation of [99mTc]DEPE as a cardiac perfusion agent

Technetium-99m labeled bis(1,2-diethylphosphino)ethane was evaluated as a cardiac perfusion agent in mice, dogs and normal human volunteers. The agent produced as a single cationic compound was prepared by a simple kit type method and had a rapid myocardial uptake in animals. The cardiac uptake of the agent in dogs averaged 4.6% of administered dose and delineated left and right ventricles by in vivo imaging. In dogs with experimental myocardial infarction, the agent was distributed according to the regional myocardial blood flow, had excellent correlation with myocardial distribution of 85Sr microspheres (r = 0.96, 0.93)] and 201Tl (r = 0.91 and 0.83), and enabled us to detect perfusion defects by in vivo scintigraphy. The agent, however, failed to have a useful degree of cardiac uptake in humans.

Neutrophil labeling: problems and pitfalls

The use of neutrophils labeled with gamma-emitting radionuclides has been shown to be acceptable for in vivo kinetic studies as well as for imaging inflammatory foci. Among the gamma-emitting radionuclides, indium-111 appears to be the agent of choice. Labeling neutrophils with 111In, however, is a relatively new technique. Although simple to perform, it involves several stages, none of which could be carried out without problems. These are discussed and the current research aimed at eliminating the problems is outlined. The knowledge of specific chemotactic receptors and surface antigens has stimulated investigations into selective neutrophil labeling that will continue to be challenging and exciting.

Albumin absorption and catabolism by isolated perfused proximal convoluted tubules of the rabbit

Overall characteristics and kinetics of tubular absorption of albumin (Alb) were studied in isolated perfused proximal convoluted tubules of the rabbit. The fate of absorbed Alb was determined in tubules perfused with low [Alb]. Alb was labeled with tritium by reductive methylation ( [3H3C]Alb). At [Alb] = 0.03 mg/ml, approximately 80% of the absorbed [3H3C]Alb was released to the peritubular bathing solution as catabolic products. Transcellular transport of intact [3H3C]Alb was negligible. Iodoacetate (IAA, 4 mM) inhibited albumin absorption (JAlb) by greater than 95% and fluid reabsorption (JV) by 55%. At [Alb] = 0.1 mg/ml the absorption rate of a derivatized cationic Alb (pI = 8.4) was fivefold greater (P less than 0.01) than that of anionic Alb. Higher cationic [Alb] had deleterious effects on tubular functions. Overall Alb absorption was of high capacity and low affinity (JmaxAlb = 3.7 ng/min per mm tubule length, apparent Michaelis constant (Km) = 1.2 mg/ml). A low capacity system that saturates at near physiological loads was also detected (JmaxAlb = 0.064 ng/min per mm, apparent Km = 0.031 mg/ml). High [Alb] did not alter the rate of endocytic vesicle formation as determined by the tubular uptake of [14C]inulin. Results show that Alb absorption is a saturable process that is inhibited by high IAA concentrations and is affected by the charge of the protein. Absorbed Alb is hydrolyzed by tubular cells and catabolic products are readily released to the peritubular side. The dual kinetics of Alb absorption may be due to a combination of adsorptive endocytosis (low capacity system) and fluid endocytosis of albumin aggregates (high capacity system). Results indicate that albuminuria occurs much before albumin absorption is saturated. The kinetic characteristics of the process of tubular absorption of albumin helps to explain the concomitance of albuminuria, increased renal catabolic rates of albumin, and renal cell deposition of protein absorption droplets in severe glomerular proteinurias.

Rapid recovery of mycobacteria from clinical specimens using automated radiometric technic

Automated radiometric technic (BACTEC Johnston Laboratories, Towson, MD) was compared with conventional mycobacterial culture procedure (Lowenstein-Jensen plus Gruft modification of Lowenstein-Jensen) in this study of 1,000 clinical specimens. In addition, 8-azaguanine inhibition was tested by radiometric technic as a rapid procedure for the differentiation of Mycobacterium tuberculosis from other mycobacterial species. A total of 59 mycobacteria was recovered. Of 28 clinically significant isolates (M. tuberculosis, M. kansasii, M. avium, M. fortuitum), the BACTEC system detected 26 (93%). Conventional methods recovered 23 (82%). The BACTEC system required an average of seven days to recover M. tuberculosis from smear-positive specimens compared with 18 days required by Lowenstein-Jensen or Gruft slants. From smear-negative specimens, the BACTEC detected M. tuberculosis in an average of 20 days versus 28 days by conventional procedure. All 20 isolates of M. tuberculosis were inhibited by 8-azaguanine, whereas 39 isolates of mycobacteria other than M. tuberculosis were not inhibited. The BACTEC system accomplishes more rapid recovery of mycobacteria and provides a higher yield than conventional methods.

Lack of recovery from radiation-induced sublethal damage in human haematopoietic cells

The effect of ionizing radiation on the growth of bone marrow cells from haematologically normal controls or from patients with acute nonlymphocytic leukaemia was studied using colony formation as an endpoint. A modified agar culture method which incorporated daily feeding with new medium was utilized to allow the growth of leukaemic cell colonies. Analysis of radiation-dose survival curves revealed that normal bone marrow cell populations exhibited a relatively steep slope, with values of D0 averaging 0.88 Gy, and essentially no shoulder to the survival curves. The leukaemic cells tested also displayed survival curves with negligible shoulders and steep slopes (average value of D0 = 0.66 Gy). The average values of D0 for normal and leukaemic cells were significantly different (P less than 0.001). The ability of hematopoietic progenitor cells to recover from the accumulation of sublethal damage was also investigated by allowing a fractionation interval between doses. As expected from the lack of significant shoulder on the survival curve, there was no evidence of recovery from sublethal damage. These results provide a rationale for the use of fractionated radiation therapy for whole-body irradiation prior to bone marrow transplant.