Showing papers on "Perfusion scanning published in 1986"

Technetium-99m-d, 1-HM-PAO: a new radiopharmaceutical for imaging regional brain perfusion using SPECT--a comparison with iodine-123 HIPDM.

Abstract: A new radiopharmaceutical, technetium-99m hexamethylpropyleneamine oxime (/sup 99m/Tc-d, 1-HM-PAO), has been reported to cross the blood-brain-barrier and to distribute in brain in proportion to regional blood flow. This study reports brain imaging obtained with /sup 99m/Tc-d,1 HM-PAO in 20 subjects; seven without evidence of cerebral disease and 13 with cerebrovascular disorders. In 16 patients comparative data were available with N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3-propanediamine ((/sup 123/I)HIPDM). Technetium-99m-d, 1-HM-PAO is retained sufficiently long to allow single photon emission computed tomography (SPECT) with widely available rotating gamma camera systems. The kinetics demonstrated a rapid brain uptake and prolonged retention of activity in cerebral structures. Good tomographic images are obtained with much higher uptake in gray than in white matter. Blood flow maps are comparable to those achieved with (/sup 123/I)HIPDM and established strokes were clearly seen, with similar details as in HIPDM studies. Delayed studies showed that the distribution in the brain remained virtually unchanged. Technetium-99m-d, 1-HM-PAO imaging appears particularly promising in routine examination of patients with cerebrovascular disorders.

Hepatic perfusion abnormalities during CT angiography: detection and interpretation.

Abstract: Twenty-seven perfusion abnormalities were detected in 17 of 50 patients who underwent computed tomographic angiography (CTA) of the liver. All but one of the perfusion abnormalities occurred in patients with primary or metastatic liver tumors. Perfusion abnormalities were lobar in nine cases, segmental in 11, and subsegmental in seven; 14 were hypoperfusion and 13 were hyperperfusion abnormalities. The causes for the abnormalities included nonperfusion of a replaced hepatic artery (n = 11), cirrhosis and nodular regeneration (n = 3), altered hepatic hemodynamics (e.g., siphoning, laminar flow) caused by tumor (n = 7), contrast media washout from a nonperfused vessel (n = 1), compression of adjacent hepatic parenchyma (n = 1), and unknown (n = 4). Differentiation of perfusion abnormalities from tumor usually can be made by comparing the morphology of the known tumor with the suspected perfusion abnormality, changes of each on delayed CTA scans, and review of initial angiograms and other imaging studies.

Positron imaging of myocardial infarction with rubidium-82

Abstract: Positron imaging provides tomographic images of regional myocardial perfusion but has required an on-site cyclotron. Rubidium-82 (/sup 82/Rb) is a short-lived (T1/2 = 75 sec) positron emitter available from a generator. In order to determine the feasibility for its use to image acute myocardial infarction, 18 patients with transmural infarctions who had coronary arteriography were given 30-40 mCi of /sup 82/Rb intravenously and positron tomographic imaging was carried out within 96 hr after onset of symptoms. Nine simultaneous transaxial slices were obtained for each patient with a positron camera. Images were also reconstructed in a long-axis, short-axis, and three-dimensional display. One study could not be interpreted because of excessive lung activity. Fourteen normals were also studied. The infarct related artery determined by angiography was correctly diagnosed by positron imaging in all 17 patients as were all three prior infarcts by readers blinded to the clinical data. No defects were observed in normals or in noninfarcted myocardial regions. This study indicates that /sup 82/Rb should be useful for perfusion imaging in patients with acute myocardial infarction. The short half-life of /sup 82/Rb should make it ideal for providing serial assessment of perfusion in patients undergoing thrombolytic therapy.

Thallium-201 myocardial imaging during coronary vasodilation induced by oral dipyridamole.

Abstract: Myocardial perfusion imaging of 201TI injected during maximum exercise has been an important diagnostic tool for coronary artery disease. Pharmacologic coronary vasodilation by i.v. infusion of dipyridamole may be used in lieu of exercise stress for purposes of diagnostic perfusion imaging. However, i.v. dipyridamole is not currently available from commercial sources for widespread routine use. Accordingly, this study was carried out in order to determine whether high dose, oral dipyridamole would be useful as a coronary vasodilator for purposes of diagnostic perfusion imaging. Fifty-eight patients undergoing diagnostic coronary arteriography also had myocardial perfusion imaging with 201TI under conditions of rest, maximum exercise stress, and high dose oral dipyridamole. Of those patients who had a defect on exercise thallium images, 75% also had a perfusion defect on thallium images after high dose oral dipyridamole. These results indicate that oral dipyridamole causes sufficient coronary arteriolar vasodilation and increase of coronary flow in nonstenotic arteries to identify perfusion defects comparable to those seen on maximum exercise stress in at least 75% of cases. In 25% of patients with exercise defects, no perfusion defect was seen after oral dipyridamole. Thus, oral dipyridamole is a potent coronary vasodilator, comparable to exercise stress in most cases, but in a minority of patients may not be comparable to exercise stress.

Two-dimensional echocardiographic evaluation of ventricular asynergy induced by dipyridamole: correlation with thallium scanning.

Abstract: Myocardial asynergies detected by two-dimensional echocardiography during intravenous administration of Dipyridamole (0.75 mg/kg) were evaluated in 54 patients referred for angiographic evaluation of chest pain. Technically adequate two-dimensional echocardiograms suitable for analysis were recorded in 42 of 54 (77.7%) patients studied. Thallium-201 myocardial perfusion scintigraphy, during dipyridamole test was performed in the same patients. Thirty of the 42 patients studied showed significant coronary narrowing at cardiac catheterization. Dipyridamole-induced wall motion abnormalities and myocardial perfusion defects were detected, respectively, in 19 (63.3%) and 21 (70%) of 30 patients with significant coronary artery disease. Wall by wall comparison of the distribution of dipyridamole-induced echocardiographic asynergy with reversible thallium-201 (/sup 201/Tl) perfusion defects demonstrated complete correlation in 42 segments examined. Three segments with perfusion defects at thallium scanning did not show asynergy during the test while two segments showing wall motion abnormalities during dipyridamole infusion did not manifest perfusion defects. Our study demonstrates that two-dimensional echocardiography during dipyridamole testing is useful in detecting patients with coronary artery disease. Furthermore, ventricular asynergies detected during the test show a high correspondence with site of myocardial perfusion defects at thallium scanning.

Regional comparison of technetium-99m DTPA aerosol and radioactive gas ventilation (xenon and krypton) studies in patients with suspected pulmonary embolism.

Abstract: The regional distribution of (99mTc)DTPA aerosol was compared with that of /sup 133/Xe (n = 30) and krypton (n = 24) in a group of patients with suspected pulmonary embolism. All patients had an aerosol study using a recently available commercial generator system, a ventilation study with one of the gases, and perfusion imaging. Regional information was assessed visually on xenon, krypton, and aerosol studies independently by considering each lung as three equal-sized zones. In addition, gas ventilation findings peripheral to regions of aerosol turbulence (hot spots) were evaluated. Only 64% of the zones were in complete agreement on xenon and aerosol. Most of the discordance between xenon and aerosol was accounted for by minor degrees of /sup 133/Xe washout retention in zones that appeared normal in the aerosol study. An agreement rate of 85% was noted between 81mKr and aerosol regionally. The regions of discordance between aerosol and gas studies, however, usually were associated with unimpressive perfusion defects that did not change the scintigraphic probability for pulmonary embolism in any patient. Regarding zones of aerosol hyperdeposition, 76% had associated washout abnormalities on xenon; however, there was no correlation between the presence of these abnormalities or perfusion abnormalities. The resultsmore » confirm the high sensitivity of /sup 133/Xe washout imaging, but suggest that radioaerosol imaging will detect most parenchymal abnormalities associated with perfusion defects of significance.« less

Noninvasive Conjunctival Oxygen Monitoring During Carotid Endarterectomy

Abstract: • Conjunctival oxygen tension (Pcjo2) was measured continuously during carotid endarterectomy in 15 patients to evaluate its sensitivity in patients receiving shunts. These studies suggest that Pcjo2tracks brain perfusion during periods of carotid artery occlusion. Reduced Pcjo2was clearly demonstrated with systemic hypotension, carotid artery clamping, and carotid shunt obstruction and clamping. Monitoring of Pcjo2is noninvasive, easy to perform, offers no danger to the patient, and allows real-time assessment of the local tissue perfusion. It provides valuable information on the effectiveness of carotid oxygen transport and, in conjunction with arterial blood gas values, expresses carotid artery perfusion relative to systemic oxygen transport. Further investigations using the Pcjo2sensor may define criteria for intraoperative carotid arterial shunting in patients with tenuous cerebral perfusion, and for prompt intervention in patients with deteriorating perfusion prior to the onset of life-threatening cerebral ischemia. (Arch Surg1986;121:914-917)

Radionuclide brain perfusion studies in suspected brain death.

Abstract: The radionuclide brain perfusion study (RPS) has been suggested as a method of confirming suspected brain death. The hospital records and RPSs of 34 patients referred were reviewed because brain death was suspected. In every case but one the RPS showed absent or drastically reduced cerebral blood flow. No patient survived more than five days, and 25 survived less than 24 hours. These findings are consistent with the results of previous reports of a total of 248 patients; only one of 248 survived and was discharged from the hospital after having had a positive RPS. The RPS is highly accurate in confirming brain death.

Fat embolism syndrome.

Abstract: The fat embolism syndrome is clinically evident in approximately 0.5-2.0% of patients with long bone fractures. The clinical signs and symptoms are evident in 60% of patients within 24 hours and 85% of patients within 48 hours after trauma. A patient is reported who complained of dyspnea and hemoptysis approximately 72 hours after sustaining a fracture to the distal tibia and fibula. Radionuclide ventilation/perfusion imaging was obtained to rule out pulmonary thromboemboli. Perfusion imaging demonstrated the characteristic diffuse, subsegmental ("mottled") appearance of fatty emboli to the lung.

Inadvertent ligation of the left pulmonary artery instead of patent ductus arteriosus. Noninvasive diagnosis by pulmonary perfusion imaging.

Abstract: Pulmonary perfusion scintigraphy was used to noninvasively evaluate a neonate four days after attempted surgical closure of a large patent ductus arteriosus (PDA). No perfusion to the left lung was seen, suggesting inadvertent ligation of the left pulmonary artery (PA). This was confirmed by cardiac catheterization and reoperation. Radionuclide pulmonary perfusion imaging is an ideal noninvasive technique for evaluating pulmonary perfusion in neonates after complicated thoracic surgery.

Prognostic significance of regional myocardial ischemia of the ventricular septum assessed by thallium-201 exercise testing

Abstract: Use of exercise thallium (Tl-201) myocardial imaging for diagnosis of coronary artery disease (CAD) is well established. Recently, Tl-201 perfusion imaging has been shown to have important prognostic value in patients with CAD.1–3 Studies have consistently shown that the presence of transient Tl-201 defects, indicating ischemic viable myocardium, predicts cardiac events.1–3 We previously reported that among patients presenting for evaluation of chest pain without known previous myocardial infarction (MI), the total number of transient Tl-201 defects is superior to other clinical, exercise, angiographic and radionuclide data for predicting cardiovascular death or nonfatal MI.1 This suggests that the extent of ischemic viable myocardium is an important determinant of the risk of a cardiac event. However, whether specific regional abnormalities of myocardial perfusion carry prognostic value is unknown. Previous studies indicate that left anterior descending (LAD) CAD may have a worse outcome than disease in other arteries4,5 but regional ischemia determined by Tl-201 imaging has not been investigated for independent prognostic value. Therefore, our previously described cohort of patients1 was reevaluated to test the hypothesis that regional myocardial schemia has independent prognostic value.

Dynamic imaging of the compliant perfusion of the lungs.

Abstract: A method for the study of the dynamics of the perfusion of the compliant vascular tree of the lungs using in vivo labelled 99mTc red cells and ECG gating is presented. Following blood pool labelling, posterior, ECG gated gamma camera images were acquired in time intervals of about 40 ms for 1,000–2,000 cardiac cycles. The images show the lungs plus the heart and great vessels The image sequence containing the periodic variation of the blood activity in the lungs during the cardiac cycle is analyzed to obtain volume curves and functional images of the amplitude and phase of the lung perfusion. The interference of the heart and great vessels with the left lung can be avoided by excluding the superimposed areas in the ROIs with, the sacrifice of part of the left lung. This technique allows dynamic visualization of the perfusion process in the compliant arterial and venous vascular trees of the lungs. The results obtained with this method in normals and some pathologies are discussed.

Myocardial perfusion imaging by digital subtraction angiography

Abstract: Several methods of digital subtraction angiography (DSA) were compared to determine which could better visualize regional myocardial perfusion using coronary angiography in seven patients with myocardial infarction, two with angina pectoris and five with normal coronary arteries. Satisfactory DSA was judged to be achieved if the shape of the heart on the mask film was identical to that on the live film and if both films were exactly superimposed. To obtain an identical mask film in the shape of each live film, both films were selected from the following three phases of the cardiac cycle; at the R wave of the electrocardiogram, 100 msec before the R wave, and 200 msec before the R wave. The last two were superior for obtaining mask and live films which were similar in shape, because the cardiac motion in these phases was relatively small. Using these mask and live films, DSA was performed either with the continuous image mode (CI mode) or the time interval difference mode (TID mode). The overall perfusion of contrast medium through the artery to the vein was adequately visualized using the CI mode. Passage of contrast medium through the artery, capillary and vein was visualized at each phase using TID mode. Subtracted images were displayed and photographed, and the density of the contrast medium was adequate to display contour lines as in a relief map. Using this DSA, it was found that regional perfusion of the contrast medium was not always uniform in normal subjects, depending on the typography of the coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventilation/perfusion mismatch of one lung in a patient with Takayasu's arteritis.

Abstract: A case of Takayasu's arteritis with pulmonary artery involvement was reported. Pulmonary artery involvement was first detected by ventilation/perfusion imaging, which showed ventilation/perfusion mismatch of the right lung, and was confirmed by pulmonary arteriography. Pulmonary artery involvement o

Assessment of Myocardial Perfusion Using Digital Angiocardiography

Abstract: Digital processing of coronary angiocardiograms provides the capability for visualizing myocardial opacification by applying contrast enhancement techniques. Smith et al. (1978) described roentgen scanning densitometry as a new method for the analysis of the spatial distribution as well as the movement of radiopaque indicators through the coronary microcirculation. The basic procedure in these studies was the subtraction of the natural image background (without contrast material) from images of the myocardial opacification period on a picture element basis. Previous work from this laboratory has similarly demonstrated the potential enhancement of angiographic contrast by digital subtraction, integration, and rescaling techniques (Brennecke et al. 1976, 1977; Heintzen et al. 1978). It was noticed that not only coronary but likewise aortic root or left ventricular injections of contrast medium could successfully be applied for the visualization of the perfused myocardium (Radtke 1982; Radtke et al. 1981a). It was the immediate goal of this experimental study to systematically examine the needs and performance of digitized myocardiography with regard to both normal and pathologic perfusion conditions of the coronary circulation.

Functional myocardial perfusion imaging by digital subtraction coronary arteriography: comparison of contrast decay rates in normal and ischemic myocardium.

Abstract: Recent advances in computer technology have enabled the generation of time-density curves of myocardial contrast medium after injection into the coronary artery, using digital subtraction angiography (DSA). Utilizing this advantage, we have described a new technique to assess regional myocardial blood flow in computerized washout analysis of the timedensity curve [1, 2]. T~/2, the contrast decay half-life derived by this technique, showed a good linear correlation with great cardiac vein flow measured by the thermodilution method and a curvilinear relationship with percentage stenosis of the left anterior descending coronary artery (LAD), as shown in Fig. 1. Therefore, T~/2 values proved to be a valuable index of regional myocardial blood flow. In the present study, we have further developed a functional imaging of T~/2 values to visualize the regional myocardial blood flow. After injecting the contrast medium into the LAD, a serial myocardial image was obtained for 20 s in the right anterior oblique projection and this image was then enhanced digitally with the DSA apparatus (TOSHIBA Digiformer X). It was then transmitted to the image-processing computer (TOSHIBA GMS-55A) and was sequentially digitized into a 64 x 64 pixel matrix window. The epicardial outline was drawn by an observer using a computer-aided outlining technique, and a time-density curve of each pixel was generated in the myocardium perfused by the LAD. The descending slope of the time-density curve was fitted to a monoexponential function with a standard least-square method (Fig. 2). The functional image was constructed to present the absolute value of the exponential decay rate constant of the respective pixel in one of four different colors--red, yellow, green, and blue. The exponential decay rates

Rationale for lung ventilation imaging

Abstract: In reply to Cosgriff and Berry, we would like to make the following comments. If ventilation scintigraphy is performed the day after abnormal perfusion images are obtained, there is a delay of 15 to 24 h before a definite report can be issued. We consider this to be unacceptable in the investigation of probable pulmonary emboli. Furthermore it is necessary to repeat the perfusion scan after 133Xe ventilation to exclude definitely (or definitely confirm) V/Q mismatch. The ventilation pattern can alter rapidly, for example as the result of mucous plugs, and it is not reasonable to compare the distribution of ventilation with that of perfusion 18 h or so earlier.