Brief courses of palliative radiotherapy for metastatic bone pain: a pilot cost-minimization comparison with narcotic analgesics.

The use of radiotherapy to treat metastatic bone pain is being challenged by claims of high cost and by more readily available, noninvasive treatment approaches. The authors assessed the effectiveness of brief courses of radiotherapy in reducing pain and estimated cost data for a pilot comparison between radiotherapy and narcotic analgesics in patients with cancer. A representative group of outpatients undergoing brief courses of radiotherapy with Karnofsky scores above 70 and without serious comorbidities were recruited from 1995 through 1996. Patients indicated their pain at rest and with movement on a scale of from 1 to 10 both before and up to 12 months after radiotherapy. Radiotherapy costs were estimated from Medicare-allowable charges. Narcotic analgesia costs were estimated from published values. In 66 patients with 131 individually treated sites, median at rest pain score decreased by about 4 points after treatment (5.58 [-/+3.28] before treatment vs. 1.55 [-/+1.8] after treatment; p < 0.05). Median with movement pain score was about 5 points lower after treatment (7.32 [-/+2.72] before treatment vs. 1.94 [-/+2.07] after treatment; p < 0.05). No differences were found when stratifying by type of pain, tumor histologic type, or skeletal site. The estimated cost per patient ranged from $1,200 to $2,500 for radiotherapy. This compares with an estimated cost of $9,000 to $36,000 for 9 months of narcotics. In this pilot study, a brief course of radiotherapy significantly reduced pain and appeared to be cost effective when compared with narcotic analgesia. A full economic evaluation is warranted.

Rapid objective measurement of gamma camera resolution using statistical moments.

An easy and rapid method for the measurement of the intrinsic spatial resolution of a gamma camera was developed. The measurement is based on the first and second statistical moments of regions of interest (ROIs) applied to bar phantom images. This leads to an estimate of the modulation transfer function (MTF) and the full-width-at-half-maximum (FWHM) of a line spread function (LSF). Bar phantom images were acquired using four large field-of-view (LFOV) gamma cameras (Scintronix, Picker, Searle, Siemens). The following factors important for routine measurements of gamma camera resolution with this method were tested: ROI placement and shape, phantom orientation, spatial sampling, and procedural consistency. A 0.2% coefficient of variation (CV) between repeat measurements of MTF was observed for a circular ROI. The CVs of less than 2% were observed for measured MTF values for bar orientations ranging from -10 degrees to +10 degrees with respect to the x and y axes of the camera acquisition matrix. A 256 x 256 matrix (1.6 mm pixel spacing) was judged sufficient for routine measurements, giving an estimate of the FWHM to within 0.1 mm of manufacturer-specified values (3% difference). Under simulated clinical conditions, the variation in measurements attributable to procedural effects yielded a CV of less than 2% in newer generation cameras. The moments method for determining MTF correlated well with a peak-valley method, with an average difference of 0.03 across the range of spatial frequencies tested (0.11-0.17 line pairs/mm, corresponding to 4.5-3.0 mm bars). When compared with the NEMA method for measuring intrinsic spatial resolution, the moments method was found to be within 4% of the expected FWHM.

Anterior, posterior, left anterior oblique, and geometric mean views in gastric emptying studies using a glucose solution.

Previous research has shown that the single anterior view of the stomach overestimates the gastric half-emptying time of a solid meal compared to the geometric mean of the anterior and posterior views. Little research has been performed comparing the various views of gastric emptying of a glucose solution. After an overnight fast, 49 nondiabetic subjects were given a 450 ml solution containing 50 g of glucose and 200 microCi of technetium-99m sulfur colloid. Sequential 1-min anterior, posterior, and left anterior oblique views were obtained every 15 min. The mean percent solution remaining in the stomach for all three views differed from the geometric mean by 1.9% or less at all time points. Average gastric half-emptying times were: geometric mean, 62.7 +/- 3.3 min; anterior, 61.9 +/- 3.2 min; posterior, 63.5 +/- 3.5 min; and left anterior oblique, 61.6 +/- 3.3 min. These half-emptying times were not statistically different. For individual patients, differences between all three views and the geometric mean were not clinically important. Approximately 95% of all patients are expected to have gastric half-emptying times measured by any of the three single views within 17 min of the gastric half-emptying time obtained using the geometric mean. The imaging of gastric emptying using glucose solutions can be performed using a convenient single view which allows continuous dynamic imaging.

Distance and depth measurements of radioactive objects utilizing rotating slant-hole collimators.

It is desirable to have an accurate method to determine the depth of various organs which are commonly imaged in nuclear medicine. The method presented here utilizes the geometrical characteristics of the rotating slant-hole collimator to calculate distances and depth. The accuracy of the calculated distance was evaluated for point sources in air separated by 11 cm. The reproducibility of the calculated distance was evaluated as a function of the extent of collimator rotation between observations for angular differences of 45 degrees, 90 degrees, 135 degrees, and 180 degrees. The theory of the method is discussed and the relative error in distance calculation analyzed mathematically as a function of (1) collimator rotation angle error, (2) collimator slant angle error, and (3) position calculation error. Our findings indicate this method to be accurate to within 2% with a reproducibility range of 3%-5% for point sources.

Human breast tumor imaging using 111In labeled monoclonal antibody: athymic mouse model.

The monoclonal antibody (MoAb) 323/A3, an IgG1, was raised against the human breast tumor cell line MCF-7 and recognized a 43 Kd membrane associated glycoprotein. Histochemical studies with the antibody detected 75% of metastatic lymph nodes, 59% of primary breast tumors, and showed some staining in 20% of benign breast lesions. For radionuclide imaging, the MoAb 323/A3 was labeled with both 125I and 111In, via covalently coupled diethylenetriaminepentaacetic acid (DTPA) by the mixed anhydride method. The antibody activity of the DTPA modified 323/A3 was assessed by an immunoassay using viable and fixed MCF-7 target cells. Male athymic nude mice bearing BT-20 human mammary tumors were injected with dual 125I/111In labeled DTPA 323/A3 via the tail veins. The animals were imaged with a gamma camera equipped with a pinhole collimator at 1-3 h, 1, 2, 3, 4 and 5 days after the tracer administration. On day 5 or 6, the animals were killed, and the biodistribution of the radiotracers was determined for the blood, thyroid, heart, lungs, liver, spleen, kidneys, gastrointestinal tract and tumor. Target to blood ratio at 6 days for the 111In tracer was 24:1 in the group with a mean tumor weight of 0.492 g, and 13:1 in another group with a mean tumor weight of 0.1906 g (day 5). However, the 125I activity showed only 3.6:1 and 5.4:1 target to blood ratios in the corresponding groups. The larger tumors localized less 111In tracer (27.13% +/- 7.57% injected dose/g, Mean +/- SD) than the smaller tumors (52.75% +/- 22.25% ID/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of left-ventricular regional dyssynergy by radionuclide angiography.

To determine whether variables obtained from Fourier analysis of gated equilibrium radionuclide angiographic (RNA) images can detect and quantify changes in left-ventricular (LV) regional wall motion induced by transient ischemia, 11 chronically instrumented dogs were simultaneously studied with hemodynamic measurements and RNA during control, left circumflex (LCx) coronary artery occlusion, and postocclusion conditions. The dogs were preinstrumented with aortic and LV catheters, electromagnetic aortic and LCx coronary artery flow probes, high-fidelity LV micromanometers, LCx coronary artery occluders, and 4-mm ultrasonic transverse LV diameter and 2-mm regional LV segment crystal pairs. Radionuclide LV regional phase and amplitude variables were calculated for each condition. The absolute changes in LCx region RNA mean, median, and standard deviation of mean phase correlated with the percent changes in LCx segment crystal fractional shortening (r = -0.71, -0.64, and -0.51, respectively; all p less than or equal to 0.01). Similarly, the absolute changes and percent changes in LCx region RNA mean amplitude per pixel correlated with the percent changes in LCx segment crystal fractional shortening (r = 0.89 and 0.94, respectively; both p less than 0.001). When these LCx region RNA phase variables were subgrouped according to mild or severe depression or augmentation in LCx segment crystal fractional shortening, progressive differences were observed between the average values for these subgroups (p less than 0.05 to p less than 0.001). These data, therefore, suggest that these regional RNA phase variables may be able to detect and quantify alterations in LV contraction patterns due to transient ischemia.

The relationship of various measures of end-systole to left ventricular maximum time-varying elastance in man.

This investigation was designed to calculate left ventricular maximum time-varying elastance (Emax), to define the relationship between Emax and pressure-volume (P-V) relations at other, more easily defined measured of end-systole, and to determine whether these measures of left ventricular contractile function can be normalized in man. Accordingly, we studied 10 subjects with simultaneous high-fidelity micromanometer left ventricular and ascending aortic pressure recordings and biplane contrast cineangiograms at control conditions and during infusion of methoxamine and nitroprusside. Emax was defined as the maximum slope of the linear relation of isochronal, instantaneous P-V data points obtained from each of the three loading conditions. Left ventricular end-systole was also defined for each loading condition as: the time of the maximum P-V ratio (maxPV), minimum ventricular volume (minPV), (-)dP/dtmin [(-)dP/dtPV], and zero systolic flow approximated by the central aortic dicrotic notch (AodiPV). The mean heart rates and LV (+)dP/dtmax were insignificantly altered during the three loading conditions. Isochronal Emax ranged from 3.38 to 6.73 mm Hg/ml (mean 5.48 +/- 1.23 [SD] mm Hg/ml) and the volume-axis intercepts at zero pressure ranged from -2 to 51 ml (mean 18 +/- 16 ml). The isochronal slope calculations were reproducible (r = .97 to .99). The end-systolic P-V slope values for the maxPV, minPV, (-)dP/dtPV, and AodiPV relations correlated with isochronal Emax (r = .90, .88, .69, and .74, respectively). The average slope values for these end-systolic P-V relations, however, underestimated the mean Emax (p less than .01 to p less than .001). The mean extrapolated volume-axis intercepts for these end-systolic P-V relations also underestimated that for Emax. Finally, the isochronal Emax and other end-systolic P-V relation slope values demonstrated inverse linear relationships with left ventricular mass (r = -.68 to -.91, p less than .05 to p less than .001). Only the Emax volume-axis intercepts showed a linear relationship with left ventricular end-diastolic volume (r = .75). Thus we conclude that the time-varying elastic properties of the left ventricle can be calculated in man, that commonly used end-systolic P-V relations significantly underestimate isochronal Emax, and that normalization of isochronal Emax and other end-systolic P-V relation slope values might be performed in man with left ventricular mass; no obvious relationship between volume-axis intercepts and measures of left ventricular or body size was apparent.

Hemodynamically important right ventricular infarction: follow-up evaluation of right ventricular systolic function at rest and during exercise with radionuclide ventriculography and respiratory gas exchange.

The prognosis and recovery of right ventricular systolic function in patients with hemodynamically documented right ventricular myocardial infarction (RVMI) is unclear. Therefore 27 patients who met hemodynamic criteria for RVMI were followed for at least 1 year. Four patients died within 1 year and 23 survived. Postmortem examination performed in three of the four patients showed extensive infarction of the right and left ventricles. Survivors underwent early and late follow-up resting radionuclide ventriculograms and late exercise studies. During long-term follow-up (1 to 4 years) resting radionuclide ventriculography demonstrated a significant improvement in right ventricular ejection fraction (30 +/- 7% to 43 +/- 8%; p less than .001) and right ventricular wall motion index (2.2 +/- 0.4 to 1.5 +/- 0.5; p less than .001) in 18 patients who survived longer than 1 year. Fourteen of these patients underwent upright bicycle exercise while off beta-blocking drugs and peak radionuclide ejection fraction was acquired after anaerobic threshold was achieved. Right ventricular ejection fraction increased significantly from 41 +/- 10% to 47 +/- 12% (p less than .001), as did the left ventricular ejection fraction (55 +/- 15% to 60 +/- 12%; p less than .05). The direction and magnitude of change of the right ventricular ejection fraction correlated significantly with the left ventricular ejection fraction (r = .82, p less than .02). Deviations from this correlation occurred in patients who had a decreased forced expiratory volume in 1 sec and an abnormal ventilatory reserve during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of tomographic thallium-201 imagining in patients with chest pain following coronary artery bypass grafting.

To determine whether thallium-201 washout profile analysis can detect regional myocardial ischemia caused by coronary artery bypass graft occlusion or progression of disease in nonbypassed coronary arteries, 19 consecutive patients with chest pain following bypass grafting were evaluated with coronary arteriography and thallium-201 scintigraphy. Twenty of the 55 coronary artery regions were perfused by an occluded bypass graft or a significantly stenosed (greater than or equal to 70% diameter narrowing) nonbypassed coronary artery, while 35 coronary regions were perfused by patent bypass grafts or insignificantly diseased coronary arteries. The tomographic thallium-201 washout profile results correlated with the bypass graft and coronary arteriographic findings (k = 0.67, P less than 0.001). The sensitivity of tomographic thallium-201 washout profile abnormalities for arteriographic abnormalities was 75%, while the specificity was 86%. The authors conclude that tomographic thallium-201 washout profile analysis may be very useful in the evaluation of patients with chest pain following coronary artery bypass grafting by detecting regional myocardial ischemia caused by occlusion of specific bypass grafts or progression of disease in nonbypassed coronary arteries.

Comparative effects of volume loading, dobutamine, and nitroprusside in patients with predominant right ventricular infarction.

To assess the value of volume loading and to determine the relative efficacy of dobutamine compared with nitroprusside therapy in acute right ventricular infarction (RVMI), 13 patients with clinical, hemodynamic, and radionuclide angiographic evidence of RVMI were evaluated. In 10 patients who had an initial pulmonary arterial wedge pressure less than 18 mm Hg, volume loading did not improve cardiac index (1.9 +/- 0.5 [SD] to 2.1 +/- 0.4 liters/min/m2), despite significant increases in mean right atrial pressure (11 +/- 2 to 15 +/- 2 mm Hg, p less than .001) and pulmonary arterial wedge pressure (10 +/- 4 to 15 +/- 2 mm Hg, p less than .001). Nine patients received dobutamine or nitroprusside in random order, while hemodynamic measurements and radionuclide angiograms were obtained simultaneously. Compared with nitroprusside, dobutamine produced a statistically significant increase in cardiac index (2.0 +/- 0.4 to 2.7 +/- 0.5 vs 2.1 +/- 0.4 to 2.3 +/- 0.5 liters/min/m2, p less than .001), stroke volume index (29 +/- 6 to 36 +/- 8 vs 29 +/- 6 to 30 +/- 6 ml/m2, p = .02), and right ventricular ejection fraction (30 +/- 8% to 42 +/- 7% vs 34 +/- 8% to 37 +/- 4%, p less than .01) by two-way analysis of variance. We conclude that volume loading does not improve cardiac index in patients with acute RVMI despite a rise in cardiac filling pressures and that infusion of dobutamine, after appropriate volume loading, produces a significant improvement in cardiac index and right ventricular ejection fraction over those after infusion of nitroprusside.

Effect of errors in reangulation on planar and tomographic thallium-201 washout profile curves.

Cardiac phantom studies were performed with and without a defect present to test the hypothesis that myocardial 201TI quantitative circumferential washout profile curves calculated from planar and rotating slant hole (RSH) collimator tomographic images are equally affected by errors in axial repositioning. Simulated stress images were acquired with the long axis of the phantom perpendicular to the camera surface and redistribution images were acquired to represent 50% 201TI washout with axial repositioning errors relative to the stress position ranging from 0 to 20 degrees in 5 degrees increments. There was a decrease in the 201TI washout profile curves compared to that expected (50%) in the wall tilted away from the camera surface, and a reciprocal increase in the 201TI washout profile curves in the wall tilted towards the camera surface for both imaging techniques whether a lesion was present or not. This effect became more pronounced as the error in axial repositioning was increased for both the planar (p less than 0.001) and the RSH tomographic (p less than 0.001) techniques. However, the deviation of the 201TI washout profile curves from that expected (50%) was greater for the planar imaging technique with or without a lesion (p less than 0.05 to 0.001). Thus, we conclude that 201TI quantitative circumferential washout profile curves calculated using this tomographic imaging technique are less affected by errors in axial repositioning than those calculated using an equivalent projection by standard planar imaging methods. These data emphasize the importance which must be placed on the repositioning of patients to obtain valid 201TI washout profile curves for the detection and localization of coronary artery disease.

Segmental coronary artery disease: detection by rotating slant-hole collimator tomography and planar thallium 201 myocardial scintigraphy.

Normal quantitative circumferential profile limits were established for a 30 degrees bilateral rotating slant-hole (RSH) collimator tomographic system. This system's value in detecting segmental coronary artery disease was assessed in a study evaluating 196 patients by thallium 201 myocardial scintigraphy and coronary arteriography. Profile curves were calculated from images of 20 healthy patients and used to identify significant coronary artery disease (greater than or equal to 70% diameter narrowing) in the left anterior descending (LAD), the right, and the left circumflex (LCx) coronary arteries. In a group of 86 patients, an abnormality on the apical or middle plane optimally identified segmental coronary artery disease. When such abnormalities were prospectively evaluated in a test group of 110 patients, the sensitivity and specificity were 79% and 93% for LAD, 90% and 90% for right, and 83% and 83% for LCx coronary artery disease. Compared with qualitative interpretation of the planar and tomographic images, quantitative tomography significantly improved the sensitivity of T1-201 imaging in detecting LAD, right, and LCx coronary artery disease (P less than .001) in patients with or without previous myocardial infarction.

Validation of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volume: comparison with cast-validated biplane cineventriculography.

To determine the accuracy of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volumes, we initially studied 14 postmortem human right ventricular casts by water displacement and biplane cineventriculography. Biplane cineventriculographic right ventricular cast volumes, calculated by a modification of Simpson's rule algorithm, correlated well with right ventricular cast volumes measured by water displacement (r = .97, y = 8 + 0.88x, SEE = 6 ml). Moreover, the mean volumes obtained by both methods were no different (73 +/- 28 vs 73 +/- 25 ml). Subsequently, we studied 16 patients by both biplane cineventriculography and equilibrium radionuclide angiography. The uncorrected radionuclide right ventricular volumes were calculated by normalizing background corrected end-diastolic and end-systolic counts from hand-drawn regions of interest obtained by phase analysis for cardiac cycles processed, frame rate, and blood sample counts. Attenuation correction was performed by a simple geometric method. The attenuation-corrected radionuclide right ventricular end-diastolic volumes correlated with the cineventriculographic end-diastolic volumes (r = .91, y = 3 + 0.92x, SEE = 27 ml). Similarly, the attenuation-corrected radionuclide right ventricular end-systolic volumes correlated with the cineventriculographic end-systolic volumes (r = .93, y = - 1 + 0.91x, SEE = 16 ml). Also, the mean attenuation-corrected radionuclide end-diastolic and end-systolic volumes were no different than the average cineventriculographic end-diastolic and end-systolic volumes (160 +/- 61 and 83 +/- 44 vs 170 +/- 61 and 86 +/- 43 ml, respectively). Comparison of the uncorrected and attenuation-corrected radionuclide right ventricular volumes demonstrated narrower 95% confidence intervals for the attentuation-corrected right ventricular volume determinations over a wide range of cineventriculographic volumes. Thus we conclude that: (1) attenuation-corrected radionuclide right ventricular end-diastolic and end-systolic volumes compare closely with those obtained by a cast-validated biplane cineventriculographic method and (2) attenuation-corrected radionuclide right ventricular volumes correspond more closely to determinations of biplane cineventriculographic right ventricular volumes and are thus likely to be more accurate than uncorrected radionuclide right ventricular volumes.

A method for removing stain precipitate and destaining sections.

Subjecting electron microscope sections to NaOH treatment removes stain precipitate from the section surface. The alkali treatment also extracts stain from the tissue itself. Following this treatment, sections can be restained to obtain clean images. Alternatively, after being viewed or photographed using one stain and then destained, the same sections can be treated with a different stain to obtain additional histochemical information.

Practical gamma camera quality control with a four-point phantom.

A gamma camera QC phantom for practical assessment of resolution (average FWHM), spatial calibration (pixels/mm), nonhomogeneity of spatial calibration, and average point-source sensitivity (cpm/muCi) was developed and evaluated. The phantom consists of four 57Co-point sources mounted on a Plexiglas base at corners of a square 10 cm on each side. Computer acquisition and processing are fully automated and require less than 1 min for point sources totaling 100 muCi (3.7 MBq) activity. The normal range of variability of measured QC parameters from a 12 wk evaluation period with four different gamma cameras (assumed to be operating normally) yielded coefficients of variation ranging from 0.3% for spatial calibration (pixels/mm) to 2.3% for sensitivity (cpm/muCi) assessments. From the normal range of variability a minimum detectable difference (MDD) was determined for each measured parameter and each gamma camera. The range of acceptable operation of a gamma camera system was set as the measured value +/- MDD for each QC parameter. The ability to detect and track small changes in the measured QC parameters was evaluated.

The digital computer: the role of functional imaging in radiology.

Over the past decade there has been an increase in the use of functional imaging. This is mainly because of the recent introduction of the digital computer, which is capable of processing measured data into images that are related to a physiological process or the function of an organ. This is a departure from the more traditional images that are mostly based on anatomical detail. The radiologist needs to become familiar with these new imaging concepts, since a continued growth in their use is inevitable.