Myocardial perfusion and function single photon emission computed tomography.
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Humans↗
Biomedical subjects
Raymond Taillefer
Publications and source records attributed to Raymond Taillefer.
Clinical applications of 99mTc-sestamibi scintimammography.
Mammography is the imaging modality of choice in detection of early, nonpalpable breast cancer. However, scintimammography may prove to be a very useful adjunct to a nondiagnostic or difficult mammography. Future prospective studies will have to be designed so that the specific clinical applications of scintimammography will be well defined. To be clinically relevant, each niche where scintimammography is potentially indicated should be clearly evaluated and incorporated into an algorithm of investigation of breast cancer, taking into consideration the relative advantages and limitations of scintimammography. Special care to obtain high-quality scintimammographic studies is mandatory. Because poor quality studies may be the major drawback, the nuclear medicine community should remind the lesson learned from radiologic mammography. Furthermore, it is also hoped that significant improvement in the scintigraphic equipment and data acquisition will be seen in a very near future to have more widespread clinical diagnostic applications of scintimammography.
Breast Neoplasms↗
Detection of silent myocardial ischemia in asymptomatic diabetic subjects: the DIAD study.
OBJECTIVE: To assess the prevalence and clinical predictors of silent myocardial ischemia in asymptomatic patients with type 2 diabetes and to test the effectiveness of current American Diabetes Association screening guidelines. RESEARCH DESIGN AND METHODS: In the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study, 1,123 patients with type 2 diabetes, aged 50-75 years, with no known or suspected coronary artery disease, were randomly assigned to either stress testing and 5-year clinical follow-up or to follow-up only. The prevalence of ischemia in 522 patients randomized to stress testing was assessed by adenosine technetium-99m sestamibi single-photon emission-computed tomography myocardial perfusion imaging. RESULTS: A total of 113 patients (22%) had silent ischemia, including 83 with regional myocardial perfusion abnormalities and 30 with normal perfusion but other abnormalities (i.e., adenosine-induced ST-segment depression, ventricular dilation, or rest ventricular dysfunction). Moderate or large perfusion defects were present in 33 patients. The strongest predictors for abnormal tests were abnormal Valsalva (odds ratio [OR] 5.6), male sex (2.5), and diabetes duration (5.2). Other traditional cardiac risk factors or inflammatory and prothrombotic markers were not predictive. Ischemic adenosine-induced ST-segment depression with normal perfusion (n = 21) was associated with women (OR 3.4). Selecting only patients who met American Diabetes Association guidelines would have failed to identify 41% of patients with silent ischemia. CONCLUSIONS: Silent myocardial ischemia occurs in greater than one in five asymptomatic patients with type 2 diabetes. Traditional and emerging cardiac risk factors were not associated with abnormal stress tests, although cardiac autonomic dysfunction was a strong predictor of ischemia.
Canada↗
Acute beta-blockade reduces the extent and severity of myocardial perfusion defects with dipyridamole Tc-99m sestamibi SPECT imaging.
OBJECTIVES: The goal of this study was to examine the effect of acute beta-blockade on dipyridamole Tc-99m sestamibi myocardial perfusion imaging (DMPI). BACKGROUND: Studies suggest that antianginal drugs may reduce the presence and severity of myocardial perfusion defects with dipyridamole stress. However, there are no data regarding specific drugs. METHODS: Patients with catheterization-proven coronary artery disease (CAD) were enrolled in this prospective, double-blind, placebo-controlled study and randomly assigned to DMPI after placebo, low-dose metoprolol (up to 10 mg), and high-dose metoprolol (up to 20 mg). Patients underwent one Tc-99m sestamibi study at rest on a separate day. The interval between DMPI studies was <or=14 days. Images were interpreted by three observers blinded to clinical data using a 17-segment, five-point model. For each image, a summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated (SDS = SSS - SRS). Images with an SSS <4 were considered normal. RESULTS: Twenty-one patients completed all four Tc-99m sestamibi studies. The sensitivity of DMPI for detection of CAD was 85.7% with placebo versus 71.4% with low- and high-dose metoprolol. In comparison with placebo, the SSS was significantly lower (p < 0.05) with low- and high-dose metoprolol (12.0 +/- 10.1 vs. 8.7 +/- 9.0 and 9.3 +/- 10.6, respectively). The SDS also was significantly lower (8.4 +/- 8.8 with placebo vs. 5.0 +/- 6.7 [p < 0.001] and 5.4 +/- 7.9 [p < 0.01] with low- and high-dose metoprolol, respectively). CONCLUSIONS: The presence and severity of CAD may be underestimated in patients receiving beta-blocker therapy undergoing dipyridamole stress myocardial perfusion imaging.
Adrenergic beta-Antagonists↗
Imaging characteristics of a novel technetium Tc 99m-labeled platelet glycoprotein IIb/IIIa receptor antagonist in patients With acute deep vein thrombosis or a history of deep vein thrombosis.
BACKGROUND: The diagnosis of recurrent deep vein thrombosis (DVT) is challenging. Imaging with radiolabeled peptides offers a new approach for detecting acute DVT. Technetium Tc 99m ((99m)Tc)-apcitide binds with high affinity and specificity to the glycoprotein IIb/IIIa receptors expressed on activated platelets and, therefore, (99m)Tc-apcitide scintigraphy should be negative with residual abnormalities caused by old, inactive thrombi and positive with new, active thrombi. METHODS: In a prospective multicenter study, (99m)Tc-apcitide imaging was performed on 38 patients with a newly diagnosed first DVT (group 1) and 40 patients with previous DVT, symptoms of postthrombotic syndrome, and chronic intraluminal abnormalities on ultrasonography (group 2). Images were interpreted in a blinded fashion by 2 experts and by newly trained nuclear medicine physicians. The sensitivity and specificity of (99m)Tc-apcitide were determined by calculating the proportion of scans in group 1 patients that were read as "positive for acute DVT" and the proportion of scans in group 2 patients that were read as "negative for acute DVT," respectively. RESULTS: When read by 2 experts, ( 99m)Tc-apcitide had a sensitivity of 92% for both readers and specificities of 82% and 90%. Agreement between the experts was excellent. However, the accuracy and interreader agreement for newly trained nuclear medicine physicians were lower. CONCLUSIONS: Technetium Tc 99m-apcitide scintigraphy has potential utility in suspected recurrent DVT because it detects most acute thrombi and has few false-positive results in patients with previous DVT. However, the accuracy appears to depend on the training and experience of the interpreters.
Acute Disease↗
(99m)Tc sestamibi breast imaging for the examination of patients with dense and fatty breasts: multicenter study.
PURPOSE: To evaluate the accuracy of scintimammography as an adjunct to physical examination and mammography in the detection of breast cancer in women with dense and fatty breasts. MATERIALS AND METHODS: A total of 558 women were prospectively enrolled from 42 centers in North America. Images were interpreted by readers blinded to the subjects' clinical history, mammographic findings, and other test results. The Breast Imaging Reporting and Data System classification was used to describe breast density. Parenchymal patterns of "heterogeneously dense" and "extremely dense" were used to classify breasts as dense, whereas "almost entirely fat" and "numerous vague densities" defined fatty breasts. Between-group differences were evaluated with the 2 test for categorical variables and Student t test for continuous variables. Accuracy of scintimammography was assessed against the core laboratory histopathologic evaluation, the standard. The 95% CIs around point estimates of sensitivity, specificity, and positive and negative predictive values were calculated with the normal approximation to the binomial distribution. RESULTS: The analyses were based on 580 breasts with an abnormality; 276 (48%) breasts were dense and 228 had a malignant lesion. Diagnostic properties for scintimammography of fatty versus dense breasts were, respectively, sensitivity, 72% versus 70%; specificity, 80% versus 78%; positive predictive value, 72% versus 67%; negative predictive value, 81% versus 81%; and accuracy, 77% versus 75% (all not significant). Scintimammography led to similar and significant changes in the posttest likelihood of cancer for both dense and fatty breasts. CONCLUSION: The diagnostic accuracy of scintimammography is not affected by breast density.
Adipose Tissue↗
Clinical validation of SPECT attenuation correction using x-ray computed tomography-derived attenuation maps: multicenter clinical trial with angiographic correlation.
BACKGROUND: Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon emission computed tomography (SPECT) myocardial perfusion images. In phantoms, normal subjects, and patients suspected of having coronary artery disease (CAD), we evaluated a new hybrid attenuation correction (AC) system that combines x-ray computed tomography (CT) with conventional stress SPECT imaging. METHODS AND RESULTS: The effect of CT-based AC was evaluated in phantoms by assessing homogeneity of normal cardiac inserts. AC improved homogeneity of normal cardiac phantoms from 11% +/- 2% to 5% +/- 1% (P < .001). Attenuation-corrected normal patient files were created from 37 normal subjects with a low likelihood (<3%) of CAD. The diagnostic performance of AC for detection of CAD was evaluated in 118 patients who had stress technetium 99m sestamibi or tetrofosmin stress SPECT imaging and coronary angiography. SPECT images with and without AC were interpreted by 4 blinded readers with different interpretative attitudes. Overall, AC improved the diagnostic performance of all readers, particularly the normalcy rate. The degree of improvement depended on interpretative attitude. Readers prone to high sensitivity or with less experience had the greatest gain in the normalcy rate, whereas a reader prone to higher specificity had improvements in sensitivity and specificity but not the normalcy rate. Importantly, improvement of one diagnostic variable was not associated with worsening of other variables. CONCLUSION: CT-based AC of SPECT images consistently improved overall diagnostic performance of readers with different interpretive attitudes and experience. CT-based AC is well suited for routine use in clinical practice.
Angiography↗
Long myotomy with antireflux repair for esophageal spastic disorders.
This report presents the long-term subjective and objective results of esophageal myotomy and fundoplication by thoracotomy in the treatment of esophageal spastic disorders. From 1977 to 1995, a total of 16 patients with esophageal spastic disorders were referred to our unit and underwent a myotomy with an added partial (n = 12) or total (n = 4) fundoplication. The median follow-up was 6 years. Assessments included clinical evaluation, esophagogram, radionuclide emptying, manometry, 24-hour pH studies, and endoscopy. From the global results, patients with pure spastic disorders (n = 8) were compared to patients with spastic disorders with an accompanying epiphrenic diverticulum (n = 8). There were no deaths, and morbidity was minimal. Preoperative symptoms were similar in all patients with spastic disorders. After surgery, the clinical outcome was significantly better in patients with spastic disorders in the presence of a diverticulum. Delays in esophageal emptying persisted after surgery. Patients with pure spastic disorders showed more diffuse functional abnormalities. Patients with a diverticulum had dysfunction mostly in the distal esophagus. Both groups showed signs of coordination and relaxation abnormalities in the lower esophageal sphincter. Myotomy with antireflux surgery resulted in decreased propulsion and contraction pressure. The resting pressure and relaxation at the level of the lower esophageal sphincter improved, but the coordination abnormalities remained. Failure resulted from either reflux complications (n = 1) or obstruction (n = 4). Patients with spastic disorders plus a diverticulum showed better clinical results and improved esophageal function after surgery when compared to patients with pure spastic disorders.
Adult↗
Attenuation correction and gating synergistically improve the diagnostic accuracy of myocardial perfusion SPECT.
BACKGROUND: The diagnostic accuracy of myocardial perfusion single photon emission computed tomography is limited by soft tissue attenuation. Artifacts may be reduced by attenuation correction (AC) or compensated for by assessment of wall motion in gated images. We studied the benefit of gating and AC, both separately and combined, in improving accuracy. METHODS AND RESULTS: Sixty-six subjects (27 with > or =50% angiographic stenosis, 5 with <50% stenosis, and 34 Bayesian normal volunteers) underwent gated AC single photon emission computed tomography. Images were reconstructed and independently viewed in 4 ways: static with motion correction (MC) only, gated with MC only, static with MC plus blur correction plus AC (referred to as combined corrections [CC]), and gated with CC. Images were interpreted by 2 blinded observers for overall presence of coronary disease and for vascular territory (left anterior descending [LAD], left circumflex [LCx], and right coronary artery [RCA]). Statistical analysis of sensitivity and normalcy was done by means of the Cochran Q test. Overall diagnostic accuracy showed statistically significant improvement (P =.05 for sensitivity, P <.001 for normalcy), progressing from static MC to gated MC to static CC to gated CC (sensitivity/normalcy = 85%/54%, 78%/62%, 93%/77%, and 96%/85%, respectively, for the 4 reconstruction and viewing approaches). Sensitivity was highest in all 3 vascular territories for the combination of gating and CC; normalcy was also highest with the same combination for the LAD and RCA territories; sensitivity/normalcy with this combination was 85%/87% for the LAD, 69%/87% for the LCx, and 89%/87% for the RCA territory. CONCLUSIONS: The combination of gating and CC provides the highest diagnostic accuracy, and gating and AC should thus be considered complementary and synergistic.
Artifacts↗