Arginine-vasopressin and the regulation of aggression in female Syrian hamsters (Mesocricetus auratus).

Arginine-vasopressin (AVP) is critical for the expression of a variety of social behaviors in many species. Previous studies have demonstrated that AVP regulates behaviors such as social communication and aggression in Syrian hamsters through the V1a receptor subtype. In male hamsters, AVP injected into the anterior hypothalamus (AH) stimulates aggression, while injection of a V1a receptor antagonist inhibits the behavior. The purpose of the present studies was to determine whether AVP influences aggression by its action in the AH in female hamsters. In the first experiment, we were surprised to find that injection of the V1a receptor antagonist, Manning compound, into the AH of intact female hamsters increased aggression. The second experiment confirmed the ability of the V1a receptor antagonist to increase aggression and found that the largest effects of the antagonist occurred at intermediate concentrations of the compound. The next experiment found that injection of AVP into the AH significantly reduced the latency to attack and the duration of aggression. Finally, we examined whether the effects of AVP and the V1a receptor antagonist on aggression differed in hamsters exposed to long 'summer-like' photoperiods or short 'winter-like' photoperiods, and found that their effects on aggression were not photoperiod dependent. In summary, contrary to what is observed in males, these data suggest that AVP in the AH may play an inhibitory role on aggression in female Syrian hamsters.

Quantitative radioimmunoimaging for radioimmunotherapy treatment planning: effect of reduction in data sampling on dosimetric estimates.

Quantitative radioimmunoimaging (serial anterior/posterior imaging and blood sampling) is useful for radioimmunotherapy treatment planning, but can be quite time consuming. To predict whether accurate radiation absorbed dose estimates can be maintained with a reduction in data sampling, 12 patients undergoing indium-111/yttrium-90 anti-CD20 monoclonal therapy for whom absorbed doses were estimated based on eight data samples (acquired at 0, 2, 4, 24, 48, 72, 96, and 144 h, respectively), were retrospectively reanalyzed using only five samples (0, 4, 24, 72, and 144 h, respectively). Calculated residence times (in h) and absorbed doses (in cGy), for the whole body, kidneys, liver, lungs, spleen, and red marrow were compared with the original values based on the eight samples using Student's paired t-test. Linear regression and Bland-Altman analysis of the two data sample groups was also performed. The mean residence times in the five- and eight-data samples groups were essentially the same (17.7 +/- 26.6 h [range, 0.3-79.0 h] versus 17.6 +/- 26.6 h [range, 0.3-79.5 h]; p = 0.72), as were the mean absorbed doses (336 +/- 411 cGy [range, 38-2434 cGy] versus 325 +/- 381 cGy [range, 39-2246 cGy]; p = 0.24). Also, the linear regressions were excellent (residence time y = 1.00x + 0.09 h [r = 0.99]; absorbed dose y = 1.06x - 7.74 cGy [r = 0.98]). Additionally, Bland-Altman analysis revealed no significant sample bias in residence time (0.03 +/- 0.68 h, 0.9% +/- 10.0) or absorbed dose (11 +/- 76 cGy, 1.0% +/- 9.3). These results demonstrate that reduced data sampling in quantitative radioimmunoimaging can be achieved without significantly altering radiation absorbed dose estimates, but with a significant savings in imaging, blood sampling, and processing time.

Planar imaging versus gated blood-pool SPECT for the assessment of ventricular performance: a multicenter study.

UNLABELLED: Gated blood-pool SPECT (GBPS), inherently 3-dimensional (3D), has the potential to replace planar equilibrium radionuclide angiography (ERNA) for computation of left ventricular ejection fraction (LVEF), analysis of regional wall motion (RWM), and analysis of right heart function. The purpose of this study was to compare GBPS and ERNA for the assessment of ventricular function in a large, multicenter cohort of patients. METHODS: One hundred seventy-eight patients referred in the usual manner for nuclear medicine studies underwent ERNA followed by GBPS. Each clinical site followed a GBPS acquisition protocol that included 180 degrees rotation, a 64 by 64 matrix, and 64 or 32 views using single- or double-head cameras. Transverse GBPS images were reconstructed with a Butterworth filter (cutoff frequency, 0.45-0.55 Nyquist; order, 7), and short-axis images were created. All GBPS studies were processed with a new GBPS program, and LVEF was computed from the isolated left ventricular chamber and compared with standard ERNA LVEF. Reproducibility of GBPS LVEF was evaluated, and right ventricular ejection fraction (RVEF) was computed in a subset of patients (n = 33). Using GBPS, RWM and image quality from 3D surface-shaded and volume-rendered cine displays were evaluated qualitatively in a subset of patients (n = 30). RESULTS: The correlation between GBPS LVEF and planar LVEF was excellent (r = 0.92). Mean LVEF was 62.2% for GBPS and 54.1% for ERNA. The line of linear regression was GBPS LVEF = (1.04 x ERNA LVEF) + 6.1. Bland-Altman plotting revealed an increasing bias in GBPS LVEF with increasing LVEF (Y = 0.13x + 0.61; r = 0.30; mean difference = 8.1% +/- 7.0%). Interoperator reproducibility of GBPS LVEF was good (r = 0.92). RVEF values averaged 59.8%. RWM assessment using 3D cine display was enhanced in 27% of the studies, equivalent in 67%, and inferior in 7%. CONCLUSION: GBPS LVEF was reproducible and correlated well with planar ERNA. GBPS LVEF values were somewhat higher than planar ERNA, likely because of the exclusion of the left atrium.

Biodistribution and dosimetry results from a phase III prospectively randomized controlled trial of Zevalin radioimmunotherapy for low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma.

UNLABELLED: Radiation dosimetry studies were performed in patients with non-Hodgkin's lymphoma (NHL) treated with 90Y Zevalin (90yttrium ibritumomab tiuxetan, IDEC-Y2B8) on a Phase III open-label prospectively randomized multicenter trial. The trial was designed to evaluate the efficacy and safety of 90Y Zevalin radioimmunotherapy compared to rituximab (Rituxan, MabThera) immunotherapy for patients with relapsed or refractory low-grade, follicular, or transformed NHL. An important secondary objective was to determine if radiation dosimetry prior to 90Y Zevalin administration is required for safe treatment in this patient population. METHODS: Patients randomized into the Zevalin arm were given a tracer dose of 5 mCi (185 MBq) (111)In Zevalin (111indium ibritumomab tiuxetan) on Day 0, evaluated with dosimetry, and then administered a therapeutic dose of 0.4 mCi/kg (15 MBq/kg) 90Y Zevalin on Day 7. Both Zevalin doses were preceded by an infusion of 250 mg/m(2) rituximab to clear peripheral B-cells and improve Zevalin biodistribution. Following administration of (111)In Zevalin, serial anterior and posterior whole-body scans were acquired and blood samples were obtained. Residence times for 90Y were estimated for major organs, and the MIRDOSE3 computer software program was used to calculate organ-specific and total body radiation absorbed dose. Patients randomized into the rituximab arm received a standard course of rituximab immunotherapy (375 mg/m(2) weekly x 4). RESULTS: In a prospectively defined 90 patient interim analysis, the overall response rate was 80% for Zevalin vs. 44% for rituximab. For all patients with Zevalin dosimetry data (N=72), radiation absorbed doses were estimated to be below the protocol-defined upper limits of 300 cGy to red marrow and 2000 cGy to normal organs. The median estimated radiation absorbed doses were 71 cGy to red marrow (range: 18-221 cGy), 216 cGy to lungs (94-457 cGy), 532 cGy to liver (range: 234-1856 cGy), 848 cGy to spleen (range: 76-1902 cGy), 15 cGy to kidneys (0.27-76 cGy) and 1484 cGy to tumor (range: 61-24274 cGy). Toxicity was primarily hematologic, transient, and reversible. The severity of hematologic nadir did not correlate with estimates of effective half-life (half-life) or residence time of 90Y in blood, or radiation absorbed dose to the red marrow or total body. CONCLUSION: 90Y Zevalin administered to NHL patients at non-myeloablative maximum tolerated doses delivers acceptable radiation absorbed doses to uninvolved organs. Lack of correlation between dosimetric or pharmacokinetic parameters and the severity of hematologic nadir suggest that hematologic toxicity is more dependent on bone marrow reserve in this heavily pre-treated population. Based on these findings, it is safe to administer 90Y Zevalin in this defined patient population without pre-treatment (111)In-based radiation dosimetry.

Single-photon emission computed tomography in the year 2001: instrumentation and quality control.

OBJECTIVE: SPECT instrumentation is more complex than that used for whole-body and planar imaging, and requires careful quality control to ensure optimum performance. Conventional and new hybrid SPECT imaging systems (coincidence and SPECT/CT) will be discussed. New imaging detector materials such as LSO and CZT will also be discussed, along with their potential advantages. Finally, basic SPECT quality control will be reviewed. After reading this article, the nuclear medicine technologist should be able to: (a) explain the use of single and multihead gamma cameras for SPECT imaging; (b) have an understanding of the potential of new hybrid SPECT imaging systems; (c) be aware of future developments in SPECT imaging technology; (d) understand the requirements for SPECT quality control, including field uniformity and center of rotation corrections; and (e) explain the benefits of using phantoms to augment SPECT quality control.

Correlation of marrow dose estimates based on serial pretreatment radiopharmaceutical imaging and blood data with actual marrow toxicity in anti-CD20 yttrium-90 monoclonal antibody radioimmunotherapy of non-Hodgkin's B-cell lymphoma.

The purpose of this study was to investigate whether marrow radiation absorbed dose estimates predict haematotoxicity following radioimmunotherapy with an yttrium-90 labelled anti-CD20 monoclonal antibody in non-Hodgkin's B-cell lymphoma (NHL). Radiopharmaceutical data from 12 NHL radioimmunotherapy patients were analysed retrospectively using three methods of marrow radiation absorbed dose estimation based on serial pretreatment indium-111 labelled anti-CD20 monoclonal antibody activity versus time data (0-144 h): (i) lumbar spine (LS) image counts; (ii) blood clearance (BL); and (iii) whole body (WB) activity. Linear regressions were performed between the methods, and between each method and the 0-6 month post-treatment platelet and white blood cell count nadir and absolute drop in count (ADC). For the range of yttrium-90 activities (740-1547 MBq), absorbed dose estimates (mean +/- sigma) were: LS, 142+/-50 cGy (range 62-233 cGy); BL, 89+/-21 cGy (range 63-140 cGy); and WB, 54+/-10 cGy (range 36-63 cGy). The LS and BL marrow estimates differed significantly (P <0.003), with a correlation coefficient r of 0.36 (P = NS), while WB correlated significantly with both LS (r = 0.50, P < 0.05) and BL (r = 0.58, P < 0.05). The range of r with platelet nadir and ADC was -0.20 < or = r < or = 0.01, except for WB with ADC (r = 0.38) (all P = NS). Values of r for white blood cell nadir were unexpectedly positive, being 0.13 for BL and 0.29 for LS (P = NS), and 0.60 for WB (P < 0.025). Values of r for white blood cell ADC were 0.36 for BL and -0.26 for LS (P = NS), and 0.50 for WB (P < 0.05). These results indicate that different commonly employed methods of estimating marrow radiation absorbed dose may yield significantly differing results, which may not correlate with actual radiation toxicity. Therefore, caution must be exercised in relying on these results to predict haematotoxicity.

Quantitative gated myocardial SPECT: effect of collimation on left-ventricular ejection fraction.

OBJECTIVE: Left-ventricular ejection fraction (LVEF) can be computed from gated myocardial perfusion SPECT studies using quantitative algorithms. The purpose of this study was to compare the LVEF obtained using the conventional high-resolution parallel-hole collimator (HRC) to the Cardiofocal collimator (CFC) (Siemens Medical Systems, Hoffman Estates, IL) using a quantitative LVEF program. METHODS: Thirty-four patients (15 men, 19 women; mean age = 62 y) had either treadmill or pharmacological stress testing with 25-30 mCi 99mTc sestamibi injected at peak stress. Conventional gated SPECT imaging was performed approximately 30 min poststress, first with the HRC collimator, then with the CFC, using the same acquisition parameters on a single-head gamma camera. Traditional (TRAD) determination of LVEF using planar gated blood pool and/or cardiac catherization also was obtained for each patient. RESULTS: The correlation in LVEF between the CFC and HRC acquisitions was excellent, r = 0.99. The correlation between CFC and TRAD LVEF was good, r = 0.95, as was the HRC and TRAD correlation, r = 0.97. The mean LVEF value for HRC was slightly less than TRAD (54% vs. 55.4%), while the CFC mean LVEF was higher (62% vs. 55.4%). Although CFC LVEF correlated well with HRC, mean LVEF value using CFC was higher than HRC. CONCLUSION: The choice of collimator may alter the LVEF obtained from gated SPECT perfusion studies.

SPECT in the year 2000: basic principles.

OBJECTIVE: SPECT has become a routine procedure in most nuclear medicine departments. SPECT provides significant technical challenges for the nuclear medicine technologist, as compared with planar imaging, in the areas of SPECT acquisition, image reconstruction, and data processing. Many new advances in SPECT methodology are becoming available, such as iterative reconstruction, multimodality fusion, and advanced gated cardiac SPECT. SPECT imaging is demanding and requires careful attention to proper acquisition protocols, whether circular or noncircular orbits, and postprocessing is becoming more complex with the addition of iterative reconstruction and attenuation correction algorithms, among others. Understanding the principles of SPECT is essential not only to produce the highest quality scans but also to identify image artifacts. After reading this article, the nuclear medicine technologist should be able to: (a) describe the historical development and benefits of SPECT imaging; (b) state the impact of image matrix size, number of projections, and arc of rotation on final SPECT image quality; (c) discuss the trade-offs between image noise content and spatial and contrast resolution in SPECT reconstruction; (d) discuss SPECT filters and their impact on image quality; (e) explain the differences between filtered backprojection and iterative reconstruction; and (f) describe the impact of attenuation and scatter in SPECT imaging and the advantages and pitfalls of attenuation correction methods.

The effect of remifentanil on biliary tract drainage into the duodenum.

UNLABELLED: Opioids cause spasm of the sphincter of Oddi. Remifentanil is metabolized enzymatically throughout the body. Its context-sensitive half-time is 3-4 min. The effect of remifentanil on the sphincter of Oddi, is unknown. We studied, in six healthy adult volunteers, the effect of remifentanil on the flow of dye from the gall bladder into the duodenum. Control hepatobiliary imaging with 5 mCi of technetium-labeled derivatives of iminodiacetic acid was performed on each volunteer. The time from IV dye (radiopharmaceutical) injection until its appearance in the duodenum was determined by continuous scanning. Two weeks later, each volunteer received remifentanil, 0.1 microg x kg(-1) x min(-1) infused for 30 min IV before the same dose of technetium-labeled derivatives of iminodiacetic acid was injected, and for the time of their control scan plus 10 min after the injection. When the dye appeared in the duodenum, the total time from injection was compared with the control value. The time from stopping the infusion until the dye appeared in the duodenum was the "recovery time." Control scan time was 20.5+/-9.9 min (mean +/- SD; range 10-33 min). Total scan time during and after the remifentanil infusion was 50.3+/-17.3 min (range 30-81 min) (P < 0002). The recovery time was 19.8+/-12.4 min (range 5-40 min). We conclude that remifentanil delays the drainage of dye from the gall bladder into the duodenum, but the delay is shorter than that reported after other studied opioids. IMPLICATIONS: Radioactive dye was injected IV into healthy volunteers to determine the time it took for the dye to appear in the duodenum. This was repeated under the influence of a short-acting narcotic analgesic, remifentanil. Remifentanil caused a much shorter delay than previously reported after morphine or meperidine.

Quantitative gated blood pool SPECT for the assessment of coronary artery disease at rest.

BACKGROUND: Planar gated blood pool imaging (GBPI) has long proven to be useful for the noninvasive assessment of ventricular function. From a practical viewpoint, gated blood pool single photon emission computed tomography (GBPS) acquisition can be accomplished in the same time as a three-view planar series, with the benefit of a tomographic perspective that avoids chamber overlap. METHODS AND RESULTS: Quantitative gated blood pool SPECT was applied to 10 patients who underwent coronary arteriography, contrast ventriculography, and planar gated blood pool imaging. For each patient, the mid-short axis oblique slice was divided into 4 discrete segments using 4 different reference models and 2 forms of segmentation. A center of mass (counts) fixed in the end-diastolic frame and segmentation that bisected the ventricular septum proved to have the highest sensitivity and specificity for determining regional wall motion abnormalities at rest in myocardium supplied by severely diseased coronary arteries (>75 %). GBPS correctly identified 19 of 21 abnormal segments (90%), with good specificity (95%), whereas ventriculography identified 12 (57%) and planar GBPI identified 9 (43%) of the segments supplied by diseased coronaries. CONCLUSION: Quantitative GBPS appears to be a sensitive method for assessing coronary artery disease at rest in myocardium perfused by severely diseased coronary arteries.

Lumbar spine duplication presenting as adolescent scoliosis. A case report.

STUDY DESIGN: A report of a case of lumbar spine duplication with the clinical appearance of adolescent scoliosis. OBJECTIVE: To increase knowledge about the pathogenesis and treatment of lumbar spinal duplication. SUMMARY OF BACKGROUND DATA: Although there have been other reports of lumbar spine duplication of this magnitude, these malformations typically are associated with severe neurologic abnormalities (dicephalus, myelomeningocele) or gastrointestinal abnormalities (omphalocele, neurenteric fistulas). Several investigators have recommended early surgical intervention for this abnormality because of the perceived risk of progressive neurologic abnormality from tethering of the cord. METHODS: In a 13-year-old girl who had truncal asymmetry, lumbar spine duplication was noted on plain radiographs. A magnetic resonance study was obtained, and the patient was observed with conservative treatment for 3 years. RESULTS: Although extensive abnormalities were noted on the magnetic resonance images, which were related to duplication of spinal cord and vertebral bodies, the patient was neurologically intact and remained so until skeletal maturity. CONCLUSIONS: This rare malformation typically has severe neurologic sequelae. Conservative management in the reported patient did not result in a progressive neurologic lesion at the time of skeletal maturity.

Prediction of radiation doses from therapy using tracer studies with iodine-131-labeled antibodies.

UNLABELLED: Tracer pharmacokinetic studies are often used in treatment planning for radionuclide therapy including radioimmunotherapy. This study evaluates the validity of using tracer studies to predict radiation doses from therapy with the same radiolabeled antibody. METHODS: Quantitative imaging and blood radioactivity were used to obtain the pharmacokinetics and radiation doses that were delivered to the total body, blood, marrow, lungs, liver, kidneys, thyroid, spleen and tumors. Tracer and therapy data for eight patients with lymphoma and one patient with breast cancer were compared using linear regression statistics. Doses of 131I-labeled antibody for the tracer studies ranged from 0.1 to 0.4 GBq (2 to 10 mCi), and therapy doses ranged from 0.7 to 5.6 GBq (20 to 150 mCi). RESULTS: Radiation doses to tissues and, in particular, the bone marrow and tumors were reliably predicted from tracer studies. In this group of patients, median dose to marrow from marrow targeting, total body and blood was 9.2 cGy/GBq for tracer studies and 7.6 cGy/GBq for therapy studies with a median difference of 0.5 cGy/GBq. Median dose to tumors was 81.1 cGy/GBq for tracer studies and 70.3 cGy/GBq for therapy studies with a median difference of 5.9 cGy/GBq. CONCLUSION: In these patients, tracer studies were predictive of the radiation doses from therapy for total body, major organs and tumors. The radiation doses to marrow and tumors, which are the usual determinants of the therapeutic index, correlated well between tracer and therapy studies (r > or = 0.95).

Validation of a knowledge-based boundary detection algorithm: a multicenter study.

A completely operator-independent boundary detection algorithm for multigated blood pool (MGBP) studies has been evaluated at four medical centers. The knowledge-based boundary detector (KBBD) algorithm is nondeterministic, utilizing a priori domain knowledge in the form of rule sets for the localization of cardiac chambers and image features, providing a case-by-case method for the identification and boundary definition of the left ventricle (LV). The nondeterministic algorithm employs multiple processing pathways, where KBBD rules have been designed for conventional (CONV) imaging geometries (nominal 45 degrees LAO, nonzoom) as well as for highly zoomed and/or caudally tilted (ZOOM) studies. The resultant ejection fractions (LVEF) from the KBBD program have been compared with the standard LVEF calculations in 253 total cases in four institutions, 157 utilizing CONV geometry and 96 utilizing ZOOM geometries. The criteria for success was a KBBD boundary adequately defined over the LV as judged by an experienced observer, and the correlation of KBBD LVEFs to the standard calculation of LVEFs for the institution. The overall success rate for all institutions combined was 99.2%, with an overall correlation coefficient of r=0.95 (P<0.001). The individual success rates and EF correlations (r), for CONV and ZOOM geometers were: 98%, r=0.93 (CONV) and 100%, r=0.95 (ZOOM). The KBBD algorithm can be adapted to varying clinical situations, employing automatic processing using artificial intelligence, with performance close to that of a human operator.

A radioimmunoimaging and MIRD dosimetry treatment planning program for radioimmunotherapy.

A treatment planning program for radioimmunotherapy employing quantitative Anger camera imaging and the MIRD formalism has been designed and implemented on a clinical nuclear medicine computer. Radionuclide residence times are calculated from linear, mono- and bi-exponential, and cubic spline fits to regional activity versus time curves, and radiation-absorbed dose estimates for all target organs for 131I, 67Cu, and 58 other radionuclides can be calculated. This software has been successfully applied to radioimmunotherapy of B-cell malignancies and breast adenocarcinomas.

Efficacy and cost considerations of intraoperative autologous transfusion in spinal fusion for idiopathic scoliosis with predeposited blood.

STUDY DESIGN: One hundred five patients with adolescent idiopathic scoliosis who underwent posterior spinal instrumentation and fusion with predeposited autologous blood, with or without intraoperative autologous transfusion, were reviewed. OBJECTIVE: To determine the benefit/nonbenefit of intraoperative autologous transfusion in diminishing the need for homologous blood and influencing post-operative hematocrit values in healthy adolescents undergoing spinal fusion for scoliosis. SUMMARY OF BACKGROUND DATA: A steady increase in the use of intraoperative autologous transfusion in recent years has occurred without guidelines regarding which procedures and patient populations would be best served. Previous studies have failed to determine the cost effectiveness and actual reduction in homologous blood exposure attributable to intraoperative autologous transfusion in adolescents who have undergone preoperative phlebotomy. METHODS: Fifty-five adolescents (intraoperative autologous transfusion group) who underwent posterior instrumentation and fusion for idiopathic scoliosis with the use of an intraoperative autologous transfusion device were compared to 50 patients (control group) who underwent the same procedure without the intraoperative autologous transfusion device. RESULTS: The average percent salvage of red blood cells by the intraoperative autologous transfusion device was 35%. The control group utilized significantly more of the predonated autologous blood than the intraoperative autologous transfusion group (1.34 units/case vs. 1.78 units/case, P < 0.05). Homologous blood usage was the same in both groups. Two patients in the intraoperative autologous transfusion group required nondirected homologous blood (total of four units), compared to three patients in the control group (total of four units) (P = 0.048). Using multiple regression analysis, the total number of transfusions was significantly correlated with the estimated blood loss and the duration of surgery in both groups. Postoperative hematocrit levels were slightly higher in the control group, but there was not a significant difference. CONCLUSIONS: The addition of intraoperative autologous transfusion to a preoperative phlebotomy program had no benefit on homologous blood exposure or post-operative hematocrit changes in this population. Blood requirements for this procedure can be met less expensively and more reliably by merely donating one's own blood.

Results of operative treatment of idiopathic scoliosis in adults.

We compared the results in eighty-one patients (average age, fifty-six years; range, forty-three to eighty-three years) who had had operative treatment of idiopathic scoliosis with those in thirty patients (average age, fifty-eight years; range, forty-five to seventy years) who had declined operative treatment. Seventy-six individuals (average age, forty-eight years; range, thirty-five to seventy-four years) who did not have scoliosis served as a control group. The average duration of follow-up was five years (range, two to seventeen years). The population base consisted of 454 patients who were seen between 1970 and 1985. The treated patients were drawn from a group of 160 patients for whom an operation had been recommended; 110 patients agreed to the operation and fifty refused. The remaining 294 patients had curves of insufficient severity to warrant concern about progression, had symptoms unrelated to the scoliosis, or had curves that did not necessitate any intervention. The functional status since the operation (for the treated patients), since recommendation of the operation (for the untreated patients), or within the last ten years (for the control group) was evaluated with a comprehensive questionnaire designed to elicit details regarding pain, fatigue, and any disability in the performance of twenty-six activities of daily living. At the most recent follow-up examination, the treated patients reported a significantly greater decrease in pain and fatigue and significantly more improvement in self-image and in the ability to perform physical, functional, and positional tasks than did the untreated patients (p = 0.0001).

Body and blood clearance and marrow radiation dose of 131I-Lym-1 in patients with B-cell malignancies.

Fifty-eight per cent of patients with B-cell malignancies had durable responses to treatment with 131I-Lym-1. Myelosuppression manifested by peripheral blood cytopenia was the radiation dose-limiting toxicity. The mean biologic half-times were 3.3 and 31.2 h for the fast and slow phases, respectively, of the blood clearance and 33.5 h for the clearance from the total body. Nonpenetrating radiation from the blood contributed 0.18 rad and penetrating radiations from the total body contributed 0.18 rad per administered mCi to the bone marrow. The average total contribution from both of these sources was 0.36 +/- 0.14 rad mCi-1. Clearances and marrow radiation doses were remarkably constant among different patients and among different therapy doses for the same patient. These results are potentially useful as an initial approximation for other mouse monoclonal antibodies of the same isotype. While radiation to normal marrow from 'spill-over' incident to specific targeting of 131I-Lym-1 on malignant B-cells in the marrow is not addressed in this publication because it is unique for each patient, it should be considered in the case of individual patients.

A new heart-sounds gating device for medical imaging.

A heart-sounds gating device has been designed and tested which identifies, individually, both the first (S1) and second (S2) heart sound from their timing relationship, providing two trigger points through the cardiac cycle for synchronizing medical images. The new heart-sounds gate utilizes dynamically varying timing windows to anticipate the occurrence of S1 and S2. The heart-sounds gate has been initially applied to nuclear imaging of the cardiac bloodpool, but may be applied to any imaging modality requiring cardiac synchronization.

Image normalization and background subtraction in T1-201/Tc-99m parathyroid subtraction scintigraphy. Effect on lesion detection.

The authors have developed two computer algorithms for T1-201/Tc-99m parathyroid subtraction scintigraphy that was performed on patients who subsequently underwent surgical exploration of the neck. Both methods employed a region-of-interest drawn around the thyroid/parathyroid glands for image realignment. The first algorithm normalized the Tl-201 and Tc-99m images using the ratio of maximum counts over the thyroid in each image. The second computer algorithm incorporated Tl-201 image background correction and normalization by the average of the ratios of maximum counts computed over each quadrant in both images. In 10 patients with confirmed parathyroid adenomas or hyperplasia, the first method yielded a 44% sensitivity. Upon reanalysis with the second algorithm, the sensitivity improved to 100%. Subsequently, in a total of 22 patients with 30 abnormal glands analyzed with the second algorithm, a sensitivity of 80% (94% for adenoma and 62% for hyperplasia) was achieved, with a specificity of 91%, as confirmed by surgery.

Alpha 2-adrenergic model of gastroparesis: validation with renzapride, a stimulator of motility.

Motility-stimulating drugs can increase gastric antral and intestinal contractions but do not usually enhance emptying unless gastroparesis is present. An alpha 2-adrenergic agonist (SC-39585A) was used to inhibit antroduodenal motility and simulate gastroparesis in dogs. SC-39585A caused dose-related inhibition of emptying of solid and liquid meals as well as the antral and duodenal motility responses to the solid meal. The motility-enhancing agent renzapride (100 micrograms/kg iv) did not enhance emptying of the solid meal under nondelayed conditions. However, at the same dose it partially reversed the delay in solid emptying but only when antroduodenal motility was incompletely (30 micrograms/kg sc) and not totally (100 micrograms/kg sc) inhibited by SC-39585A. This was done in part by antagonizing antral but not duodenal inhibition of motility. Renzapride was also effective orally in reversing the delay in solid emptying. Similarly, renzapride reversed the delay in liquid emptying caused by SC-39585A (30 micrograms/kg sc). An alpha 2-adrenergic agonist can be used to model gastroparesis in dogs by inhibiting antroduodenal motility and can also be used to examine the actions of motor stimulants, such as renzapride, which promote gastric emptying.