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PubMed1986

Indomethacin and dexamethasone decrease oleic acid-induced pulmonary protein leak in rabbits.

Similarities between oleic acid (OA)-induced pulmonary injury and clinical adult respiratory distress syndrome (ARDS) have resulted in extensive use of this model. Using technetium 99m (Tc-99m)-labeled human serum albumin (Tc-HSA) we examined the effect of indomethacin (a prostaglandin synthetase inhibitor) and dexamethasone (a corticosteroid) alone and in combination on OA-induced pulmonary protein leak. Computer-acquired dynamic gamma camera imaging before (15 min), during, and after (60 min) OA infusion were used to generate time-activity curves for lung and heart regions. A lung:heart activity ratio curve with a positive slope indicates pulmonary capillary protein leak of the labeled substance. Tc-99m labeling of red blood cells followed by OA injury showed no significant change in slope, indicating that lung hemorrhage was not being measured; however, Tc-HSA showed significant protein leakage following OA injury. Pretreatment with indomethacin or dexamethasone did not significantly alter either the preinsult or the postinsult slope. Combined pretreatment with indomethacin and dexamethasone significantly decreased, but did not eliminate, the pulmonary protein leak produced by OA injury. Our results indicate that multiple factors are involved in the production of the pulmonary capillary leak in OA-induced lung injury. In addition to the possible therapeutic efficacy of combined corticosteroids and nonsteroidal antiinflammatory drugs, our results demonstrate that these substances may be useful in defining the pathophysiology involved in permeability pulmonary edema.

Animals↗
PubMed2000

Evaluation of gastric motility by Fourier analysis of condensed images.

In this study Fourier analysis was applied to condensed images of gastric emptying with the aim of evaluating the amplitude and frequency of gastric contractions as well as gastric emptying in patients with various well-defined disorders. In 15 controls, 65 patients with progressive systemic sclerosis (PSS), 41 patients with diabetes mellitus type I (DM), 12 patients with pyloric stenosis and 9 patients who had undergone gastric surgery, gastric emptying was determined after ingestion of a semi-solid test meal. In addition, condensed images were generated to evaluate the amplitude and frequency of gastric contractions by means of Fourier analysis. In PSS and DM patients, gastric emptying and contraction amplitudes were significantly reduced (P<0.01). Patients with pyloric stenosis displayed regular peristalsis but significantly delayed emptying (P<0.01). Patients who had undergone gastric surgery showed normal or rapid gastric emptying associated with decreased amplitudes (P<0.01). The frequency of gastric contractions in the patient groups was not different from that in controls. This study showed Fourier analysis of condensed images to be a rapid and feasible approach for the evaluation of gastric contractions. Depending on the underlying disorder, gastric emptying and peristalsis showed both corresponding and discrepant findings. Data on gastric contractions provided additional information compared with results obtained by conventional emptying studies. Therefore, both parameters should be routinely assessed to further improve characterisation of gastric dysfunction by scintigraphy.

Adult↗
PubMed1999

Application of mathematical methods in dynamic nuclear medicine studies.

Dynamic nuclear medicine studies can generate large quantities of data, and their analysis consists essentially of a reduction of these data to a small number of relevant parameters which will assist in clinical decision making. This review examines some of the mathematical techniques that have been used in the process of data reduction and attempts to explain the principles behind their application. It particularly identifies the techniques that have stood the test of time and demonstrated their usefulness, many of which are now available as standard tools on nuclear medicine processing computers. These include curve processing tools such as smoothing, fitting and factor analysis, as well as tools based on empirical models, such as the Patlak/Rutland plot and deconvolution. Compartmental models and vascular models are also examined and the review finishes with a summary of some functional images and condensed images. It is concluded that an appreciation of the principles and limitations of these mathematical tools is valuable for their correct usage and interpretation of the results produced.

Cardiovascular System↗
PubMed1987

Hepatic perfusion index in cirrhotic livers--investigation of imaging and analytical procedures.

Dynamic hepatic scintigraphy was performed in a group of cirrhotic patients to evaluate the optimum imaging and analytical procedures necessary for the measurement of the hepatic perfusion index (HPI). Patients were studied in the posterior (n = 19) and the anterior (n = 14), positions, with either 0.2 or 0.5 ml of 99Tcm sulphur colloid administered as a rapid bolus injection. In each subject, three ROIs (small, medium and large) were drawn over the liver, and time-activity perfusion curves were generated. Analytical techniques were developed to allow flexibility in selecting the arterial and portal venous phases of the liver perfusion curve. The quality of the bolus, expressed as the full width at half-maximum of the left ventricular time--activity curve, was independent of the bolus volumes and patient positioning. The dispersion in the data and the inter-observer variation were less in the anterior view using medium and large ROIs, compared with the anterior small ROI and all the posterior ROI sizes. A time delay between liver and kidney arterial phases, if ignored, produced statistically significant effects on the values of the HPI. We conclude that HPI investigations are best performed in the anterior projection. Data analysis using a large liver ROI is preferred, and flexible data-processing techniques are recommended, particularly in the presence of a liver and kidney arterial time delay.

Adult↗
PubMed2005

Osteoid osteoma of the spine: a novel technique using combined computer-assisted and gamma probe-guided high-speed intralesional drill excision.

STUDY DESIGN: A report of five cases of thoracolumbar osteoid osteoma treated with combined computer-assisted and gamma probe-guided high-speed drill excision. OBJECTIVES: To document the surgical technique consisting of a combination of both computer-assisted and gamma probe-guided high-speed drill excision for osteoid osteoma of the spine. SUMMARY OF BACKGROUND DATA: Curative treatment of spinal osteoid osteoma is performed by surgical intralesional excision of the nidus, but intraoperative localization of the nidus is often difficult. Although intraoperative gamma-probe guidance facilitates accurate localization of the nidus, wide surgical resection of the bony structure is still mandatory to ensure removal of the nidus. Computer-assisted surgery has been proven to facilitate surgical intervention in spinal surgery. However, there is no clinical report regarding the application and usefulness of computer-assisted intralesional excision of the osteoid nidus. Excision of the nidus with a computer-assisted high-speed drill and intraoperative gamma probe control may result in complete intralesional excision without sacrificing more bone than necessary. METHODS: One day before surgery, patients were injected with radioactive mTc-oxidronate. With a computed tomography-based electro-optical navigation system, real-time virtual images of the osteoid osteoma were generated by matching the intraoperative surface with preoperative computed tomography images. The osteoid osteoma was excised with the use of an image-guided high-speed drill, and complete excision was controlled with a gamma detection probe. RESULTS: Excision of the nidus was confirmed by relief of symptoms, postexcision computed tomography scans, and histologic evaluation on clinical and radiographic follow-up observation. All five patients reported immediate complete relief of characteristic pain and no evidence of recurrence after 6 to 33 months of follow-up observation. There were no complications. CONCLUSIONS: The combination of both computer-assisted surgery and gamma probe-guided high-speed drill excision for osteoid osteoma of the spine helps to localize and excise the nidus of the osteoid osteoma with minimal bone resection of the posterior spinal structures.

Adolescent↗
PubMed1987

Functional imaging of the heart.

The generation of functional images from the time-activity curves of individual pixels in the gated blood-pool study has become a routine part of most nuclear medicine computer systems. These images have the advantage of extracting useful functional information from the entire study and presenting it in an easily interpretable format. One can rapidly examine them, especially the phase and amplitude images, to seek out potential abnormalities of contraction and conduction. These are not designed to be "stand alone" images and correlation with the remainder of the study, including the cine display, is required. In addition to their use in assessing abnormalities of either ventricular chamber, they also have been shown to be useful in delineating atrioventricular borders in both the left and right sides of the heart. This facilitates definition of regions of interest for the calculation of ejection fractions. These images are produced at no increased expense or inconvenience to the patient and therefore should always be evaluated.

Heart↗
PubMed1992

Diagnosis of venous leakage by 133Xe corporeal clearance after intracavernous injection of prostaglandin E1 in poorly responding patients.

133Xe corporeal clearance after intracavernous (IC) prostaglandin E1 (PGE-1) injection was assessed in detecting venous leakage (VL) in a group of impotent patients with poor clinical response to PGE-1 injection. 133Xe corporeal washouts were done in the flaccid state and at full erection or at 20 min after the IC injection of 20 micrograms PGE-1 in cases where no full erection occurred in sequence on two separate days. In each case, data were acquired in frame mode after intracorporeal injection on one side of the midline just behind the glans of 0.1 ml, namely, 1-2 mCi (34-74 MBq) 133Xe in saline for 20 min. A time-activity curve was generated from the region of interest (ROI) at the site of injection and a computer routine was used to calculate clearance half-time (T1/2) in min and flow rate (Q) in ml per 100 g tissue per min. The data of 20 patients with equivocal response to IC PGE-1 were analysed. Of them, 14 had venous leakage and six had no vascular impairment (NVI). Venous leakage was proved by Doppler analysis, cavernosography after PGE-1, and/or selective arteriography. Twelve of 14 patients with VL had enhanced 133Xe corporeal clearance after PGE-1 with a significant decrease in T1/2 (mean +/- S.D.) from 115.9 +/- 196.0 to 13.3 +/- 13.4 (P less than 0.05) and increase in Q from 2.1 +/- 2.2 to 7.5 +/- 5.6 (P less than 0.01). In contrast, all six patients with NVI had decreased 133Xe corporeal clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2001

Bronchial edema alters (99m)Tc-DTPA clearance from the airway surface in sheep.

Airway wall edema, prominent in inflammatory airways disease, may alter barrier properties at the airway air-liquid interface such that normal absorption of soluble substances into the airway circulation is altered. We studied the effects of bradykinin-induced airway wall edema on the clearance of the soluble tracer technetium-99m-labeled diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) from subcarinal airways in sheep (n = 8). (99m)Tc-DTPA (6-10 microl) was delivered by a microspray nozzle inserted through a bronchoscope to a fourth-generation bronchus both before and 1 h after bradykinin (20 ml; 10(-6) M) had been infused through a cannulated and perfused bronchial artery. Airway retention (by scintigraphy) and blood levels of radiolabel were monitored for 30 min after the local deposition of (99m)Tc-DTPA. During control conditions, 85-90% of the tracer cleared from the deposition site within 30 min. The maximum blood level during that time was 17% of the total delivered tracer. However, 1 h after bradykinin infusion, there was significant retention of the marker at the deposition site with clearance within 30 min reduced to 63-70% and decreased blood levels of radiolabel (8%; both P < 0.05). These results demonstrate that moderate airway wall edema alters blood uptake and removal of soluble substances delivered to the subcarinal airways. We suggest that the interplay between vascular and mucociliary clearance routes will impact the resident time for clearance of soluble air toxins and/or therapeutic agents from the epithelial surface.

Animals↗
PubMed1992

Comparison of technetium-99mC and phytate aerosol in ventilation studies.

The image quality obtained with technetium-99mC aerosol (Technegas) was evaluated and compared with that obtained with 99mTc-phytate aerosol generated by a jet nebulizer. Fifty patients underwent ventilation scanning after inhalation of each aerosol (mean interval of 3 days). Four views (anterior, posterior, left and right posterior oblique) were recorded with 200 k precounts. Both sets of images were blindly compared for (i) qualitative evaluation of images, (ii) quantitation of penetration (PI) and heterogeneity (HI) indices and (iii) assessment of ventilation state. Peripheral penetration was the same in 64% of cases, greater with 99mTc-C in 27% and greater with 99mTc-phytate in 9%. The use of 99mTc-C led to fewer and less intense foci of bronchial or gastric activity. The differences for 99mTc-C and 99mTc-phytate, respectively, between mean PI (0.78 vs. 0.70) and HI (15 vs. 18) were not significant. Consideration of all the parameters indicates the overall superiority of 99mTc-C. The final interpretation of the lung ventilation scans was, however, similar with both tracers.

Administration, Inhalation↗
PubMed2006

Spatial accuracy of fMRI activation influenced by volume- and surface-based spatial smoothing techniques.

As improvements in cortical surface modeling allowed accurate cortical topology in brain imaging studies, surface-based methods for the analysis of functional magnetic resonance imaging (fMRI) were introduced to overcome the topological deficiency of commonly used volume-based methods. The difference between the two methods is mainly due to the smoothing techniques applied. For practical applications, the surface-based methods need to quantitatively validate the accuracy of localizing activation. In this study, we evaluated the spatial accuracy of activation detected by the volume- and surface-based methods using simulated blood oxygenation level-dependent (BOLD) signals and MRI phantoms focusing on the influence of their smoothing techniques. T1- and T2-weighted phantoms were acquired from BrainWeb () and used to extract cortical surfaces and to generate echo planar imaging (EPI) data. Simulated BOLD signals as the gold standard of activation in our experiment were applied to the surfaces and projected to the volume space with random noise. Three-dimensional isotropic Gaussian kernel smoothing and two-dimensional heat kernel smoothing were applied to the volume- and surface-based methods. Sensitivity and 1-specificity, which are truly and falsely detected activations, and similarity measures, which are spatially and statistically similar for the gold standard and detected activations, were calculated. In the results, the surface-based method showed the sensitivity and similarity scores of about 12% higher than the volume-based method. In conclusion, the surface-based method guarantees better spatial accuracy for the localization of BOLD signal sources within the cortex than the volume-based method.

Brain↗
PubMed2000

Evidence for cytotoxic T lymphocyte response against human lung cancer: reconstitution of antigenic epitope with peptide eluted from lung adenocarcinoma MHC class I.

BACKGROUND: Cancer-associated, major histocompatibility complex (MHC)-restricted peptide antigens have been elucidated in human melanomas and ovarian, breast, and renal carcinomas; but relatively little is known about lung cancer antigens. METHODS: To work toward delineation of lung cancer-associated antigens, we developed tumor infiltrating lymphocytes (TILs), peripheral blood mononuclear cell-derived cytolytic T cell lines (CTL), autologous lung cancer cell lines, and normal lung cell lines from 17 patients undergoing lung cancer resections. The TILs and CTL lines were subsequently evaluated for markers of activation and specific lysis of autologous or allogeneic lung cancer cell lines or both. RESULTS: Freshly isolated TILs contained a more activated T cell population compared with the patients' peripheral blood T cells as evidenced by an increased expression of HLA-DR, CD25, and CD45RO. TILs isolated from 15 patients lysed allogeneic lung cancer lines. TILs lysed autologous lung cancer but not autologous normal lung or Epstein-Barr virus transformed B cell lines (B-LCL) in 4 of 8 cases tested, suggesting tumor specificity. A CTL line (RHPBL57.1) was generated from peripheral blood mononuclear cells of an HLA-A24(+) patient by stimulation against an established HLA-A24(+) allogeneic lung cancer cell line. RHPBL57.1 lysed the lung cancer cell line in an HLA-A24-restricted manner. Moreover, RHPBL57.1 specifically lysed autologous B-LCL pulsed with peptides, eluted from MHC class I and isolated from the HLA-A24(+) lung cancer cell line. CONCLUSIONS: TILs isolated from patients with lung cancer are predominantly an activated population of T cells with evidence of tumor and MHC class I-restricted lysis. Furthermore, we provide evidence for a lung cancer-associated, MHC class I-bound peptide antigen(s) that reconstitutes the epitope recognized by a lung cancer specific CD8(+) T cell line derived from a patient with lung cancer.

Adenocarcinoma↗
PubMed1987

Exercise-induced pulmonary haemorrhage in the horses: results of a detailed clinical, post mortem and imaging study. VII. Ventilation/perfusion scintigraphy in horses with EIPH.

Detailed post mortem examination of the lungs of horses with exercise-induced pulmonary haemorrhage (EIPH) has demonstrated significant small airway disease and intense bronchial arterial proliferation in the dorsocaudal lungfields. The purpose of this study was to investigate ventilation and perfusion distribution in the lungs of a similar group of horses to compare changes in the live animal with the previously reported post mortem findings. Thoracic radiography and ventilation/perfusion (V/Q) scintigraphy were performed on five racing Thoroughbreds with recent histories of EIPH. Parametric images of V/Q ratios for left and right lungfields were also generated from the scan images. In all horses, ventilation and perfusion deficits were demonstrated in the dorsocaudal areas of the lung corresponding closely to the observed radiographic lesions. In particular, the perfusion images and V/Q ratio displays indicated that, in affected areas of lung, pulmonary arterial perfusion was the more seriously impaired. This finding appears to confirm the post mortem evidence of reduced pulmonary arterial perfusion and bronchial arterial dominance in these areas. Ventilation deficits in the same areas also confirmed the likelihood of partial airway obstruction consistent with the small airway disease noted in previous post mortem observations. These results suggest that the vascular and airway lesions demonstrated in detailed post mortems of horses with EIPH are also functionally important in affected horses, even at rest. As a consequence of the apparent persistent, insidious and progressive nature of the lesions associated with EIPH there are serious long term implications for management of the condition.

Animals↗
PubMedDate not supplied

An evaluation of four methods of 111In planar image quantification.

The accurate quantification of the in vivo distribution of 111In labeled platelets, other cells, and proteins with a scintillation camera is important in clinical and experimental medicine. Planar techniques of image quantification were therefore evaluated with the aim of improving on the accuracy, and simplifying the techniques currently in use. The attenuation of the 172- and 247-keV photons of 111In, singly and in combination, was determined for varying diameter flat sources (3.4 to 16.9 cm). The influence of region of interest (ROI) selection on the shape of the attenuation curves was also determined for five different ROI's. Defining the attenuation curves mathematically generated parameters of fit for three approaches to in vivo quantification, namely: a single exponential geometric mean approach that takes into account source size, depth-dependent, and depth-independent buildup factor approaches to account for the contribution of scatter. The accuracy of these techniques was ascertained and compared to the classical geometric mean method. This was done in a waxen phantom of a human thorax with a hollow liver and spleen. The results indicated that the depth-independent buildup factor is the best method; the error for quantification in the spleen was 0.8% +/- 2.2%. The classical geometric mean approach gave a corresponding error of 43.3% +/- 3.4%. Since the attenuation of the two energies of 111In differ, their ratio changes with depth. This phenomenon was investigated with the goal of determining whether the depth of an object can be estimated from one set of planar images. This was not successful.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1985

Lymphscintigraphy in peripheral lymphedema using technetium-labelled human serum albumin: normal and abnormal patterns.

Lymphscintigraphy using Tc-99m human serum albumin (HSA) was examined in 23 patients with peripheral leg lymphedema. Each was injected intradermally with one mCi in the medial web space bilaterally. Images of the lower pelvis and both thighs were obtained within five minutes after injection using an extralarge field view camera GE 500A with low energy all purpose collimator interfaced with G.E. Star computer. These images were acquired in dynamic byte mode, 128 X 128 matrix size, every minute for 40 minutes. Delayed images for this region and of both legs were also taken at 90 minutes and time activity curves from comparable regions of interest over the inguinal area bilaterally were generated. Three patterns emerged: 1--normal lymph flow (12 patients) characterized by symmetrical or nearly symmetrical early appearance of lymphatics (medial bands) with visualization of inguinal and pelvic lymph nodes in both early and delayed images. Time activity curves showed step ladder rise, in "pulses" every three to four minutes. 2--enhanced lymph flow pattern (6 patients) was characterized by rapid movement of radiolabelled albumin through dilated lymphatics, occasionally with subcutaneous pooling, and both larger and more numerous inguinal and pelvic nodes on the lymphedematous side. 3--obstructed lymph flow (5 patients) was characterized by subcutaneous pooling, absent lymphatics, (medial bands) and flat, time activity curve on the lymphedematous side (only background activity) and absent inguinal and pelvic nodes. On delayed images, where lymphatic obstruction was incomplete there was delayed appearance of inguinal pelvic nodes which were fewer and smaller compared to the nonedematous side.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

CT in occult disease of the skull base and basilar foramina.

Current generation CT with its high resolution technology, its capability for soft tissue and bone imaging through an expanded gray scale, its feature of thin section imaging (1.5 mm cuts), and its capacity for multiplanar imaging (axial, direct coronal, coronal, and sagittal reformations, etc.) bring a truly unique element to radiologic evaluation of the skull base and basilar foramina. CT modifications continue to develop, such as dynamic scanning. Thus CT provides the possibility of improved radiologic diagnosis in a clinically problematic area--the recognition of occult disease, invariably tumor, involving the skull base, the neurovascular foramina that penetrate it, and portions of the subjacent visceral cranium and the suprajacent brain. The purpose of this manuscript is to demonstrate and define a role for CT in the possible solution of this problem. Equally, a role for the selective and continued use of conventional radiology and other imaging modalities to both guide and complement CT is considered.

Brain Neoplasms↗
PubMed2003

Prokinetic effect of cisapride on pedicled stomach, small bowel and colon grafts replacing the esophagus after esophageal resection.

Cisapride is a potent third generation prokinetic agent acting on postganglionic receptors by increasing the release of acetylcholine. In a prospective, self-controlled study the prokinetic action of cisapride was tested on pedicled stomach, jejunum and colon grafts used for substitute after esophageal resection. Between 1995 and 1998 15 patients with gastric pull up, 10 patients with colon replacement or bypass and eight patients with free jejunum transplant or jejunum replacement were evaluated. Esophageal transit scintigraphy was performed before and after cisapride administration. From the time-activity curves, the half-life of radiolabeled bolus in the esophagus was calculated and preadministration and postadministration half-lives were compared. Cisapride significantly reduced the half-life of radiolabeled bolus in the substitute in the case of stomach and jejunum replacement, while for colon replacement the results were dispersed too widely to yield significant difference. Cisapride exerts prokinetic effect on pedicled stomach and jejunum substitutes after esophageal resection.

Adult↗
PubMed2003

Salivary gland scintigraphy: the use of semiquantitative analysis for uptake and clearance.

OBJECTIVE: Quantitative analysis of (99m)Tc-pertechnetate salivary gland scintigraphy has been used in the evaluation of salivary gland function, but so far no one method can be considered optimal for this task. In this study, a semiquantitative method providing 2 functional parameters for objective assessment of salivary gland function by scintillation camera imaging was tested. METHODS: Twenty-one patients referred for (99m)Tc-pertechnetate thyroid scanning were studied. Two patients with salivary complaints were also included. Dynamic imaging of the anterior head using a scintillation camera was started after a bolus intravenous injection of 185 MBq (5 mCi) (99m)Tc-pertechnetate at 1 frame per 30 s for 30 min. At 15 min after injection, diluted lemon juice was administered orally. Analysis of the dynamic study included time-activity curves of 4 salivary glands (right and left parotid and right and left submandibular). Two parameters of function were defined: uptake rate, taken as the value of the initial slope of the time-activity curve, and washout fraction, which was the relative mobilizable radioactivity from each salivary gland after ingestion of the sialogogue. A parametric image of the washout fraction was also generated. RESULTS: The images showed gradual uptake in the parotid and submandibular glands. Washout was noted immediately after ingestion of the lemon juice. The pattern of the time-activity curve in all glands showed an early fast-rising part followed by a slow-rising component to nearly a plateau within 6-10 min after injection. The mean value of the uptake rate parameter was 0.10 +/- 0.09 cps/s. There was no significant difference between the parotid and submandibular glands or the right and left sides. Uptake in the parotid gland was 1.5-2 times that in the submandibular gland. The washout fraction was 1.40 +/- 1.60 for the parotid glands and 0.77 +/- 0.41 for the submandibular glands (P = 0.005). CONCLUSION: The quantitative analysis method including the uptake rate and the washout fraction parameters would enable objective assessment of salivary function and provide a reproducible means for follow-up of functional impairment in certain diseases.

Adolescent↗
PubMedDate not supplied

Comparison of exercise, dipyridamole, and adenosine by use of technetium 99m sestamibi tomographic imaging.

BACKGROUND: Pharmacologic stress has been shown in animal studies to induce high degrees of myocardial hyperemia. At these levels of myocardial blood flow, the myocardial uptake of technetium 99m sestamibi may plateau and may affect the diagnostic accuracy. This study compared the effects of myocardial hyperemia induced by exercise, dipyridamole, and adenosine on 99mTc sestamibi tomographic imaging in normal subjects and patients with ischemic coronary artery disease. METHODS AND RESULTS: Twenty subjects (group I, 10 normal subjects; group II, 10 patients with known coronary artery disease) underwent 99mTc sestamibi tomographic imaging after rest, exercise, dipyridamole infusion, and adenosine infusions on separate occasions. Total and background-corrected myocardial counts of the resulting images were calculated. Visual and computer-generated quantitative myocardial perfusion defect analysis was performed in subjects in group II. For subjects in both groups I and II, there were no significant differences in the background-corrected myocardial counts obtained with exercise, dipyridamole, and adenosine stress. There were no significant differences in the myocardial perfusion defects obtained after the three different modes of stress, including percentage defect size, stress deficit percentage, percentage of ischemia, count deficit index, and defect nadir. CONCLUSIONS: The myocardial uptake of 99mTc sestamibi in normal subjects and patients with coronary artery disease is comparable after exercise, dipyridamole, and adenosine stress. In addition, the defect sizes and intensities with 99mTc sestamibi after all forms of stress were equivalent. Thus 99mTc sestamibi, in combination with either adenosine or dipyridamole infusions, provides imaging data equivalent to those with exercise and may be considered an alternative in patients unable to undergo adequate exercise.

Adenosine↗