Accurate estimates of absolute left ventricular volumes from equilibrium radionuclide angiographic count data using a simple geometric attenuation correction.

To simplify and clarify the methods of obtaining attenuation-corrected equilibrium radionuclide angiographic estimates of absolute left ventricular volumes, 27 patients who also had biplane contrast cineangiography were evaluated. Background-corrected left ventricular end-diastolic and end-systolic counts were obtained by semiautomated variable and hand-drawn regions of interest and were normalized to cardiac cycles processed, frame rate and blood sample counts. Blood sample counts were acquired on (d degree) and at a distance (d') from the collimator. A simple geometric attenuation correction was performed to obtain absolute left ventricular volume estimates. Using blood sample counts obtained at d degree or d', the attentuation-corrected radionuclide left ventricular end-diastolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-diastolic volumes (r = 0.95 to 0.96). However, both mean radionuclide semiautomated variable left ventricular end-diastolic volumes (179 +/- 100 [+/- 1 standard deviation] and 185 +/- 102 ml, p less than 0.001) were smaller than the average cineangiographic end-diastolic volume (217 +/- 102 ml), and both mean hand-drawn left ventricular end-diastolic volumes (212 +/- 104 and 220 +/- 106 ml) did not differ from the average cineangiographic end-diastolic volume. Using the blood sample counts obtained at d degree or d', the attenuation-corrected radionuclide left ventricular end-systolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-systolic volumes (r = 0.96 to 0.98). Also, using blood sample counts at d degree, the mean radionuclide semiautomated variable left ventricular end-systolic volume (116 +/- 98 ml, p less than 0.05) was less than the average cineangiographic end-systolic volume (128 +/- 98 ml), and the other radionuclide end-systolic volumes did not differ from the average cineangiographic end-systolic volume. Therefore, it is concluded that: 1) a simple geometric attenuation-correction of radionuclide left ventricular end-diastolic and end-systolic count data provides accurate estimates of biplane cineangiographic end-diastolic and end-systolic volumes; and 2) the hand-drawn region of interest selection method, unlike the semiautomated variable method that underestimates end-diastolic and end-systolic volumes, provides more accurate estimates of biplane cineangiographic left ventricular volumes irrespective of the distance blood sample counts are acquired from the collimator.

The lag phase of gastric emptying: clinical, mathematical and in vitro studies.

UNLABELLED: The lag phase of gastric emptying reflects, in large measure, the clinically important milling function of the stomach, but there is little agreement on the best way to acquire, analyze and characterize lag phase data of gastric emptying studies. METHODS: Twenty normal volunteers were fed a standard 99mTc-sulfur colloid scrambled egg and toast breakfast and imaging data were acquired at 15-min intervals in both anterior and posterior projections with the subject seated. RESULTS: In a significant percentage of the subjects, the stomach count rate rose above the initial count rate, even with geometric mean correction. We attributed the count rate rise to meal self-absorption and conducted mathematical and in vitro experiments, the results of which supported this thesis. Attempts at modeling the data with power exponential fits were unsuccessful in many cases and were complex, nonintuitive and of limited clinical utility. Accordingly, gastric emptying rates were determined by simple linear regression from geometric mean data. The starting index (the time at which the regression line equalled 100%) was calculated to reflect the lag phase. Normal ranges were determined for men and women. CONCLUSION: Our method of test performance is simple, eliminates confounding variables and provides results with intuitive meaning and with direct clinical relevance.

An improved FORTRAN program for calculating modulation transfer functions: concise communication.

An improved FORTRAN II program for calculating modulation transfer functions (MTFs) is presented. The program features (A) simplified input-data specifications; (B) a conversational mode of use; and (C) graphic printout of the MTF curve.

Simplified method for determining the modulation transfer function for the scintillation camera.

The modulation transfer function (MTF) has long been accepted as an index of scintillation camera system resolution, but the technique necessary for the derivation of the MTF has discouraged its widespread acceptance because of its tedious and time-consuming nature. We have shown that the generation of LSFs for input into computer programs for MTF generation can be accomplished very easily and in short periods of time by using a simplified method. Establishment of the validity of this simplified procedure should contribute to more widespread utilization of the MTF in routine quality control programs as a check for crystal deterioration, electronic circuitry degradation, and/or collimator damage.

Correlation of right and left ventricular ejection fraction and volume measurements.

First-pass radiocardiography and biplane angiocardiography were performed on 13 patients with left-sided regurgitant valvular disease (R+) and 7 patients without regurgitation but with coronary artery disease and/or cardiomyopathy (R-). Right and left ventricular volumes and ejection fractions were calculated and compared. In the R- group, corresponding right and left ventricular volumes and ejection fractions correlated highly with each other (r = 0.86-0.89, p approximately equal to 0.01). Ejection fractions in the R+ group correlated (r = 0.64, p less than 0.05) only because stroke volume correlation was very high (r = 0.93), with end-diastolic and end-systolic volumes showing no significant correlation. Right ventricular ejection fraction (RVEF) decreased significantly with increasing mean pulmonary artery pressure (PAP) in both R- and R+ groups. The correlation of RVEF and LVEF in the R- group appears to be multifactorial in origin, consisting of effects of increased PAP, the mechanical interference of an enlarged left ventricle on the right ventricle, and direct biventricular ischemic effects. In the R+ group, the correlation appears to be due to only increased PAP and its sequelae.

Cholescintigraphy: gallbladder nonvisualization secondary to neoplasm.

Whereas the diagnosis of acute cholecystitis is characterized by nonvisualization of the gallbladder with Tc-99m iminodiacetic acid derivatives, nonvisualization is not specific for acute cholecystitis. The first reported case of nonvisualization of the gallbladder due to neoplasm is added to an expanding list of causes of nonvisualization other than the more frequent causes: acute and chronic cholecystitis.

A simplified radiopharmaceutical accountability record-keeping system.

A comprehensive system has been developed to ensure that a patient receives the proper radiopharmaceutical dose and that records of accountability are conveniently maintained. A radiopharmacy assay/utilization record serves as the control document for source products and derived new products. Color-coded numbered labels are used to maintain accountability among source products, derived products, prescriptions, logbooks, and patient doses. These measures have proved effective in simplifying documentation, minimizing dose-administration errors, and providing for radiopharmaceutical accountability.

First-pass anger camera radiocardiography: biventricular ejection fraction, flow, and volume measurements.

First-pass (FP) right and left ventricular ejection fraction results were compared with equilibrium radiocardiographic (ER) measurements, and FP left ventricular ejection fraction (LVEF) values were compared with biplane contrast angiographic (CA) measurements in 13 patients with and seven patients without regurgitant valvular disease. Regurgitant fractions were calculated from differences between the FP right and left ventricular stroke volumes. Ejection fractions determined by FP were precise (mean CV = 9.6% RVEF, 13.4% LVEF). Mean LVEF by FP and ER were essentially identical, and both were lower than by CA. LVEF(FP) correlated with LVEF by ER and CA (r = 0.88, p less than 0.001). Mean RVEF by both FP and ER were also correlated (r = 0.82, p less than 0.001). There was correlation between FP (corrected) and CA left ventricular stroke (r = 0.77), end-diastolic (r = 0.88), and end-systolic (r = 0.91) volumes, but underestimates were noted when uncorrected flows were used (r = 0.52-0.71). The FP regurgitant fraction measurements separated the patients with regurgitant valvular disease from those without and agreed well with CA grading of regurgitation.

Blood clearance rates of technetium-99m albumin preparations: concise communication.

Technetium-labeled human serum albumin (HSA) is extensively used as a cardiac imaging agent. An evaluation of the blood-clearance rates of electrolytically reduced HSA (EHSA) and four stannous-reduced HSA (SnHSA) preparations was conducted in dogs, and was compared with that of radioiodinated HSA (IHSA). The EHSA was found to have a clearance rate only about 1.5 times that of IHSA, whereas the SnHSA agents were cleared at two to five times the rate of IHSA. Thus, EHSA has definite advantages over SnHSA preparations for the purposes of blood-volume determinations required in quantitative cardiac studies and for the reduction of extravascular background in the accurate delineation of cardiac boundaries.

Treatment of medullary carcinoma of the thyroid with I-131.

We present a patient with radioiodine concentration in pulmonary metastases presumably arising from medullary carcinoma of the thyroid. Transient symptomatic improvement occurred after treatment with a large dose of sodium iodide (I-131). Although radioiodine concentration in medullary carcinoma of the thyroid is rare, the findings in this patient and in other recent reports suggest that an attempt should be made to determine whether a medullary carcinoma concentrates radioiodine. If so, I-131 treatment might be beneficial.

Estimates of left-ventricular volumes by equilibrium radionuclide angiography: importance of attenuation correction.

To compare the accuracy of attenuated and attenuation-corrected equilibrium radionuclide angiographic (RNA) left ventricular (LV) volume estimates, we studied 23 consecutive patients with biplane contrast cineangiography (CINE). Attenuated RNA end-diastolic (ED) and end-systolic (ES) volumes were calculated from background-corrected ED and ES counts obtained from hand-drawn regions of interest that were normalized to cardiac cycles processed, frame rate, and blood activity. A simple, geometric attenuation correction was performed to obtain attenuation-corrected RNA LV volumes. The attenuated and attenuation-corrected RNA LV EDV estimates correlated with the CINE LV EDVs ; however, the attenuation-corrected RNA LV EDV estimates correlated more closely. Also, the average attenuation-corrected RNA LV EDV did not differ significantly from the mean CINE LV EDV. Attenuated and attenuation-corrected RNA LV ESV estimates also correlated with the CINE LV ESVs , but the attenuation-corrected RNA LV ESV estimates correlated more closely. Also, the average attenuation-corrected RNA LV ESV did not differ significantly from the mean biplane CINE LV ESV.

Skeletal scintigraphy with technetium-99m-tetraphenyl porphyrin sulfonate for the detection and determination of osteomyelitis in an animal model.

UNLABELLED: This article explores the accumulation of 99mTc-tetraphenyl porphyrin sulfonate (TPPS4) at inflammatory sites, especially osteomyelitis, and compares the results with 111In Cl3 and 111In-WBC in an animal model. METHODS: Osteomyelitis was induced in 12 New Zealand white rabbits by injecting staphylococcus aureus in the left tibia. Three weeks later, radiographs confirmed the disease. Two hours later, after injection of 74 MBq 99mTc-TPPS4, scintiphotos of the lower extremities were acquired and repeat scintiphotos were obtained 24 hr after injection of 5.55 MBq 111In Cl3. After these studies, 24- and 48-hr scintiphotos of the lower extremities were acquired after injecting 5.55 MBq 111In-labeled WBC. RESULTS: The left tibia averaged three times the uptake with 99mTc-TPPS4 compared with right tibia; with 111In Cl3 and 111In WBC the ratios are two times. These three radiopharmaceuticals reveal positive images, but the image quality using 99mTc-TPPS4 is better, as would be expected from the more favorable physical characteristics of 99mTc and the higher uptake. CONCLUSION: The traditional combination of three-phase bone and 67Ga-citrate scintigraphy can be replaced by a single injection of 99mTc-TPPS4 with imaging as early as 2 hr. Finally, the use 99mTc-TPPS4 should result in a substantial reduction in radiopharmaceutical cost.

The treatment of benign thyroid disease.

The treatment of benign forms of thyroid disease is reviewed. Endemic goiter is a public health problem preventable by the addition of iodine to the food or water supply. Endemic and familial goiters are treated with replacement doses of I-thyroxine, as are sporadic colloid goiters and goiters resulting from chronic thyroiditis. Hyperfunctioning autionomous nodules without thyrotoxicosis and cystic nodules require no specific therapy. Prophylaxis against diffuse or nodular goiter after radiation to the head or neck for therapeutic purposes with thyroxine replacement therapy is debatable. All forms of hypothyroidism, including incipient types, require replacement thyroxine therapy, but this should be undertaken cautiously in older patients and in those with evidence of ischemic myocardial disease. Myxedema coma requires vigorous treatment and detailed supervision because of dismal mortality rates. Iodine 131 is the treatment of choice in diffuse toxic goiter, but alternative forms.

Uptake of 131I-metaiodobenzylguanidine by 6-23 rat medullary thyroid carcinoma.

Uptake of 131iodine-metaiodobenzylguanidine (131I-MIBG) by 6-23 rat medullary thyroid carcinoma (MTC), was studied in vitro and in vivo. In vitro, there was an 8-fold increase in 131I uptake by 6-23 cells when labeled with 131I-MIBG (131I 24 +/- 15 cpm/10(6) cells, 131I-MIBG 196 +/- 9 cpm/10(6) cells). MIBG uptake in vitro was the same at 4 degrees C and 37 degrees C. In contrast, 131I-MIBG uptake by PC-12 rat pheochromocytoma cells were 200 times greater (131I-MIBG 42,412 +/- 6,755 cpm/10(6) cells). 131I-MIBG uptake by rat MTC cells in vitro were of a comparable magnitude to the uptake of 131I-MIBG by rat ileal enterochromaffin cells (RIE-1) and mouse colon cancer cells (MC-26). In vivo, uptake of 131I-MIBG by 6-23 MTC tumor was considerably less than in the normal tissues (muscle, liver, spleen, kidney, adrenal and thyroid). Gamma camera studies of 131I-MIBG uptake by 6-23 MTC tumors growing in Wag-Rij rats were only transiently positive in 1 out of 4 rats studied. We conclude that 131I-MIBG is poorly taken up by rat medullary thyroid carcinoma and is an unpredictable marker for localization of rat MTC.

Determining blood and plasma volumes using bioelectrical response spectroscopy.

We hypothesized that an electric field (inductance) produced by charged blood components passing through the many branches of arteries and veins could assess total blood volume (TBV) or plasma volume (PV). Individual (N = 29) electrical circuits (inductors, two resistors, and a capacitor) were determined from bioelectrical response spectroscopy (BERS) using a Hewlett Packard 4284A Precision LCR Meter. Inductance, capacitance, and resistance from the circuits of 19 subjects modeled TBV (sum of PV and computed red cell volume) and PV (based on 125I-albumin). Each model (N = 10, cross validation group) had good validity based on 1) mean differences (-2.3 to 1.5%) between the methods that were not significant and less than the propagated errors (+/- 5.2% for TBV and PV), 2) high correlations (r > 0.92) with low SEE (< 7.7%) between dilution and BERS assessments, and 3) Bland-Altman pairwise comparisons that indicated "clinical equivalency" between the methods. Given the limitation of this study (10 validity subjects), we concluded that BERS models accurately assessed TBV and PV. Further evaluations of the models' validities are needed before they are used in clinical or research settings.

Verification of global cerebral ischaemia using scintigraphy.

The induction of global cerebral ischaemia in laboratory animals is difficult to accomplish and has been even more difficult to verify. Most reported verification methods suffer from lack of sensitivity or from being traumatic and highly invasive. We describe a non-traumatic global cerebral ischaemia verification technique which is quantitative, simple, and highly sensitive. Radioactive technetium-99m pertechnetate is injected intravenously during the ischaemic phase of an experiment and the appearance of radioactivity within the animal's head is quantitated using a gamma camera and nuclear medicine computer. Radioactivity levels below the visual perception threshold are readily measured, thus providing a high degree of confidence in assessing the partial or total nature of cerebral ischaemia.

Scintigraphic findings in stress fractures.

Forty-two patients suspected of having stress fractures were evaluated by serial roentgenograms and by one total-body scan with detailed views of suspicious areas. Stress fracture was the ultimate clinical diagnosis in twenty-one patients, and in fifteen of them the roentgenograms were normal while the scintigram was positive. The false negative rate for the roentgenograms was 71 per cent. In eleven of the fifteen patients, the roentgenograms eventually became positive. There were five positive scintigrams from causes other than stress fracture, giving a false positive rate for scintigraphy of 24 per cent. The bones with stress fractures included the metatarsals, calcaneus, tibia, femur, and fibula.

Regulation of gonadotropin response in testicular feminization syndrome.

The effects of hormonal manipulation on gonadotropin, androgen, and estrogen concentrations in a patient with testicular feminization syndrome (TFS) were studied to clarify the feedback regulation of gonadotropins. Baseline serum LH concentrations were normal to high and FSH concentrations were normal despite markedly elevated plasma testosterone concentrations, implying the lack of a reciprocal control relationship, and fluoxymesterone administration failed to alter gonadotropin or androgenic steroid levels. Clomiphene administration resulted in a rise in both LH and androgen levels, while moderate doses of exogenous estrogens effected a diminution in testosterone but did not significantly alter the levels of gonadotropins. Following gonadectomy, these same doses of estrogens produced a dramatic fall in the very high postoperative levels of gonadotropins. These results suggest that gonadotropin regulation is mediated by estrogens and not directly by androgens in TFS.

99mTc-PIPIDA cholescintigraphy in the diagnosis of gallbladder disease.

The efficacy of 99mTc cholescintigraphy in the diagnosis of gallbladder disease was studied in 116 patients. Sixty-one demonstrated gallbladder visualization (normal) and 55 had nonvisualization. In patients with acute abdominal pain, test sensitivity is 100%, specificity is 77%, and accuracy is 83% for the diagnosis of acute cholecystitis; no patient with gallbladder visualization had acute cholecystitis. Test sensitivity for any form of gallbladder disease is 66%, specificity is 82%, and accuracy is 71%; excluding patients with laboratory evidence of hepatobiliary disease, the predictability of acute or chronic cholecystitis increases to 100%. Cholescintigraphy demonstrated common bile duct patency in all eight post-cholecystectomy patients referred for evaluation of possible choledocholithiasis. Thus, gallbladder visualization with 99mTc-PIPIDA virtually excludes the diagnosis of acute cholecystitis, an abnormal test is a good predictor of gallbladder disease because of high specificity, and cholescintigraphy is extremely safe and simple to perform and may be used to demonstrate common bile duct patency.

Mediastinal scintigraphy for parathyroid localization in hyperparathyroidism.

Two cases are reported demonstrating that mediastinal scintigraphy for hyperparathyroidism should be routinely performed along with scintigraphy of the neck region. Because of the relative cost-benefit ratio, consideration should also be given to performing the procedure before the initial surgery. For the most accurate diagnosis and favorable outcome, our cases suggest that scintigraphic physiologic results should be correlated with anatomic results of conventional radiography.