Evaluation of surgical gamma probes.
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Evaluation Studies as Topic↗
Biomedical subjects
A van Lingen
Publications and source records attributed to A van Lingen.
Prediction of improvement of regional left ventricular function after revascularization using different perfusion-metabolism criteria.
UNLABELLED: Increased myocardial uptake of 18F-fluorodeoxyglucose (FDG) in regions with perfusion defects (perfusion-FDG mismatch) has been shown to predict functional recovery after revascularization; conversely, a concordant decrease in perfusion and FDG uptake (perfusion-FDG match) represents scar tissue (varying from subendocardial to transmural scar) that will not improve in contractile function after revascularization. Several recent studies have used a mild reduction in perfusion or FDG uptake (or both) as an indicator of viable tissue. To our knowledge, this criterion has not been validated against functional outcome after revascularization. This study aimed to compare the predictive value for functional recovery of these different perfusion-metabolism criteria. METHODS: Forty-two patients referred for revascularization were studied with early resting 201Tl SPECT (to evaluate perfusion) and FDG SPECT. Contractile function was evaluated before and 3-4 mo after revascularization using two-dimensional echocardiography. Angiography was not repeated. RESULTS: Two hundred six dysfunctional segments were identified; functional recovery occurred in 71 segments. The 206 dysfunctional segments were divided into five groups: group I, segments (n = 37) with normal perfusion; group II, segments (n = 69) with a mild reduction in perfusion (> or =60% of normal 201Tl uptake) without increased FDG uptake (mild match); group III, segments (n = 29) with a mild reduction in perfusion and increased FDG uptake (mild mismatch); group IV, segments (n = 46) with a more severe reduction in perfusion (<60% of normal 201Tl uptake) without increased FDG uptake (severe match); and group V, segments (n = 25) with a 201Tl activity < 60% and increased FDG uptake (severe mismatch). The mean wall motion score improved significantly in groups I, III and V but not in groups II and IV. Improvement of function was observed in 76% of group I segments, in 69% of group III segments and in 68% of group V segments. In contrast, only 13% of group II segments and 7% of group IV segments improved after revascularization. CONCLUSION: The results indicate that normal perfusion and mismatch patterns (either mild or severe) are predictive of functional recovery, whereas match patterns (either mild or severe) are predictive of absence of recovery. Match patterns are likely to represent different degrees of scar tissue, ranging from subendocardial to transmural scars. To identify segments with a high likelihood of improvement of function after revascularization, integration of information on perfusion and FDG uptake appears mandatory.
Angioplasty, Balloon, Coronary↗
Predictive value of planar 18F-fluorodeoxyglucose imaging for cardiac events in patients after acute myocardial infarction.
This long-term study examines the predictive value of planar myocardial 18F-fluorodeoxyglucose (FDG) imaging for cardiac events after acute myocardial infarction (AMI). From December 1989 to April 1991, 59 consecutive patients with AMI had undergone planar rest thallium-201 (Tl-201)/FDG imaging for viability assessment; 53 (42 men) were included in this study. Mean follow-up was 47 +/- 15 months. Cardiac events were defined as cardiac-related death, reinfarction, late revascularization, and unstable angina pectoris. A mismatch pattern was defined as a FDG uptake exceeding Tl-201 uptake by > or = 20%. A concordant reduction in flow and metabolism was defined as a match. In the mismatch group (n = 39) were 19 events versus 1 event in the match group (n = 14) (p <0.009). In the mismatch group were 5 cardiac deaths, 3 reinfarctions, 7 late revascularizations, and 4 patients had unstable angina pectoris. There was 1 cardiac death in the match group. The event-free rate estimated using Kaplan Meier curves for patients with and without a mismatch was significantly different (p = 0.018). The relative risk for patients with a mismatch for developing a future cardiac event was estimated at 7.8 versus patients with a match. Thus, planar myocardial FDG imaging shortly after AMI has important prognostic significance for prediction of future cardiac events. Patients with a mismatch shortly after AMI have a high risk for future cardiac events on medical therapy.
Aged↗
Volumetric measurements of bone mineral density of the lumbar spine: comparison of three geometrical approximations using dual-energy X-ray absorptiometry (DXA)
Measurements of bone mineral density using dual-energy X-ray absorptiometry (DXA) gives area values (g cm-2) rather than true volumetric values (g cm-3). To calculate the vertebral volume using planar postero-anterior and lateral DXA values, several different geometrical approximations were used: cubic, cylindrical with a circular cross-section and cylindrical with an elliptical cross-section. The aim of this study was to compare these geometrical approximations with each other and with a reference standard, defined as the volume found on a computed tomographic (CT) scan. L2 and L3 were evaluated in a phantom study. Volume approximations by the cube or cylinder with circular cross-section geometry showed more than a 50% overestimation (range 54-74%). However, the elliptical cylinder approach showed very good agreement: 2.1% and 1.2% for L2 and L3, respectively, when compared to the CT volumes. In addition, we performed four patient studies with both CT and DXA to evaluate the elliptical cylinder estimate in a clinical setting. For L2 and L3, the mean relative difference was less than 2%. We conclude that the elliptical cylinder approach results in the most accurate bone volume estimates in both the phantom and patients.
Absorptiometry, Photon↗
Increased uptake of iodine-123-BMIPP in chronic ischemic heart disease: comparison with fluorine-18-FDG SPECT.
UNLABELLED: To evaluate the potential role of 15-p-[123I]iodophenyl-3-(R,S)-methylpentadecanoic acid (BMIPP) for the assessment of myocardial viability, the patterns of BMIPP versus 18F-fluorodeoxyglucose (FDG) uptake were evaluated in patients with chronic ischemic heart disease. METHODS: Twenty-one patients with stable chronic coronary artery disease underwent resting TI SPECT to delineate myocardial perfusion followed by FDG SPECT to detect residual viability in regions showing perfusion defects. Resting BMIPP SPECT was obtained on a separate day. SPECT images were displayed as polar maps (13 segments) and analyzed semiquantitatively. A total of 273 segments were analyzed. RESULTS: In 87 (32%) of the segments, a perfusion defect was observed. In perfusion defects, the distributions of BMIPP/TI (mis)matches were significantly different (p < 0.0001) between the FDG viable (n = 42) and nonviable (n = 45) segments. A BMIPP/TI mismatch (BMIPP uptake higher than perfusion) was found in 74% of FDG viable segments, whereas a BMIPP/TI match (BMIPP uptake equal or lower than perfusion) was found in 69% of FDG nonviable segments. Agreement between matching or mismatching of segments was assessed to be 71%. Agreement was 81% when the data were analyzed on a patient basis. The observed frequency of BMIPP/TI mismatches was significantly higher (p < 0.05) in segments with an old myocardial infarction (20 of 36; 55%) than it was in subacute infarcted myocardium (5 of 21; 24%). CONCLUSION: In chronically hypoperfused myocardium, an increased BMIPP uptake relative to perfusion was detected, which is different from the decreased BMIPP uptake often reported in (sub)acute myocardial ischemia. Therefore, the interval from infarction may be an important factor in the interpretation of BMIPP scintigraphic data. Increased BMIPP uptake was associated with FDG/TI mismatches and may, therefore, confirm myocardial viability. Some segments with a FDG/TI mismatch, however, revealed a BMIPP/TI match. These segments may contain viable but more severely damaged tissue. Further studies on functional recovery are warranted to assess the significance of a BMIPP/perfusion (mis)match for tissue viability.
Aged↗
Comparison of fluorine-18-FDG with rest-redistribution thallium-201 SPECT to delineate viable myocardium and predict functional recovery after revascularization.
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Aged↗
Comparison between 360 degrees and 180 degrees data sampling in thallium-201 rest-redistribution single-photon emission tomography to predict functional recovery after revascularization.
Whether 360 degrees or 180 degrees imaging should be used in cardiac thallium-201 single-photon emission tomography (SPET) studies to detect coronary artery disease remains controversial. Moreover, the relative diagnostic accuracy of 360 degrees and 180 degrees 201Tl SPET for the assessment of myocardial viability has never previously been studied. The aim of this study was to perform a direct comparison between 180 degrees and 360 degrees data sampling to detect viable myocardium in patients undergoing revascularization; in order to allow optimal detection of viability a rest-redistribution protocol was used. The 201Tl results were compared with improvement of regional wall motion abnormalities after the revascularization, which was considered as the "gold standard" for myocardial viability. Thirty-two patients, scheduled for revascularization, underwent rest-redistribution 201Tl SPET, using a 360 degrees arc. Raw data along a 180 degrees arc (45 degrees RAO to LPO) were selected from the original 360 degrees data sets (both early an late 201Tl images). All SPET data were analysed semiquantitatively using circumferential profiles of the short-axis images; the data were displayed in polar maps. Criteria for viability included percentage 201Tl redistribution and percentage 201Tl activity on the late image. Regional wall motion was assessed with two-dimensional echocardiography before and 3 months after revascularization. The sensitivities of 360 degrees and 180 degrees imaging for the prediction of functional recovery were 82% and 89%, respectively, whereas the specificities were 51% and 55%, respectively. The diagnostic accuracy of 360 degrees imaging was 62% and that of 180 degrees imaging 67%. This study shows that 360 degrees and 180 degrees imaging have comparable diagnostic accuracy in the prediction of functional recovery after revascularization. With the newer dual-head gamma camera systems with each detector opposing each other, 360 degrees imaging may be preferred.
Angioplasty, Balloon, Coronary↗
Optimal metabolic conditions during fluorine-18 fluorodeoxyglucose imaging; a comparative study using different protocols.
Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) can identify viable myocardium in patients with coronary artery disease. Recently, FDG imaging with single-photon emission tomography (SPET) and 511-keV collimators has been described. To obtain optimal image quality in all patients, cardiac FDG studies should be performed during hyperinsulinaemic glucose clamping. It has been suggested that FDG imaging after the administration of a nicotinic acid derivative may yield comparable image quality to clamping. We studied eight patients and compared the image quality of cardiac FDG SPET studies after oral glucose loading, after administration of a nicotinic acid derivative (acipimox, 250 mg orally) and during hyperinsulinaemic glucose clamping. The image quality was expressed as the myocardial to blood pool (M/B) activity ratio, which is used as a measure of the target-to-background ratio The M/B ratios were comparable after clamping and acipimox (2.8+/-0.8 vs 2.9+/-0.7), whereas the M/B ratio was lower after oral glucose loading (2.2+/-0.3, P<0.05 vs clamp and acipimox). To determine the clearance of FDG from the plasma, blood samples were drawn at fixed time intervals and the FDG activity was measured in a gamma well counter. The FDG clearance was significantly lower after oral glucose loading (T(1/2) oral load=16. 2+/-5.7 min) as compared with clamping (T(1/2) clamp=8.1+/-3.1 min) and acipimox (T(1/2) acipimox=10.7+/-4.0 min, NS vs clamp, P<0.05 vs oral load). It may be concluded that FDG SPET imaging after acipimox administration yields image quality and clearance rates comparable to those obtained during clamping. FDG SPET in combination with acipimox may useful in clinical routine for the assessment of myocardial viability.
Aged↗
Prediction of improvement of contractile function in patients with ischemic ventricular dysfunction after revascularization by fluorine-18 fluorodeoxyglucose single-photon emission computed tomography.
OBJECTIVES: We evaluated the use of fluorine-18 fluorodeoxyglucose (FDG) and single-photon emission computed tomography (SPECT) to predict improvement of left ventricular ejection fraction (LVEF) after revascularization. BACKGROUND: FDG SPECT has recently been proposed for assessment of myocardial viability. However, FDG SPECT still awaits validation in terms of predicting improvement of contractile function after revascularization in patients with poor left ventricular (LV) function. METHODS: Fifty-five patients with contractile dysfunction (including 22 with LVEF < 30%) underwent FDG SPECT during hyperinsulinemic glucose clamping and early thallium-201 SPECT (to assess perfusion). Improvement of LV function was evaluated 3 months after revascularization with echocardiography and radionuclide ventriculography. RESULTS: The 55 patients were arbitrarily classified into two groups: 19 with three or more viable, dysfunctional segments on FDG SPECT and 36 with less than three viable, dysfunctional segments. LVEF increased significantly in the first group, from 28 +/- 8% (mean +/- SD) before to 35 +/- 9% (p < 0.01) after revascularization. In the second group, LVEF remained unchanged after revascularization (45 +/- 14% vs. 44 +/- 14%, p = NS). The 22 patients with severely depressed LV function were similarly classified into two groups: 14 with three or more viable segments on FDG SPECT in whom LVEF improved significantly (25 +/- 6% vs. 32 +/- 6%) and 8 with less than three viable segments in whom LVEF remained unchanged (24 +/- 6% vs. 25 +/- 6%). CONCLUSIONS: This study shows that FDG SPECT can identify patients in whom LV function improves after revascularization. Because SPECT is widely available, this technique may contribute to more routine use of FDG for determination of viability.
Echocardiography↗
Metabolic imaging using F18-fluorodeoxyglucose to assess myocardial viability.
Over the past 10 years, F18-fluorodeoxyglucose (FDG) imaging with positron emission tomography (PET) has emerged as an important technique in the delineation of myocardial viability. Using this technique it has become possible to predict recovery of ventricular function after revascularization in patients with chronic coronary artery disease. Data from long-term (although retrospective) follow-up studies have demonstrated that patients with viable myocardium on FDG PET who do not undergo revascularization are prone to cardiac events, including cardiac death and non-fatal infarction. The same studies have pointed out that patients with viable tissue on FDG PET, who do undergo revascularization, improve substantially in symptoms related to congestive heart failure. To allow FDG imaging in centers without PET equipment, recent studies have evaluated the use of FDG imaging with single photon emission computed tomography (SPECT) and 511 keV collimators. Preliminary data using this alternative approach are promising, but need further confirmation. In this review the experience with FDG imaging (using either PET or SPECT) in the assessment of tissue viability in patients with coronary artery disease will be discussed.
Coronary Disease↗
FDG SPECT in the assessment of myocardial viability. Comparison with dobutamine echo.
The use of 18F-fluorodeoxyglucose (FDG) imaging with single photon emission computed tomography (SPECT) has been introduced recently to assess myocardial viability. Several centres have now gained experience with cardiac FDG SPECT imaging, and this report is a summary of the currently available FDG SPECT data. Three studies have compared FDG SPECT with FDG positron emission tomography and demonstrated good agreement between them. Initial results in patients undergoing revascularization suggest that FDG SPECT can predict improvement in contractile function after revascularization. Although the initial results are promising, larger studies are needed to determine the precise role of FDG SPECT in the assessment of myocardial viability.
Cardiotonic Agents↗
Prediction of improvement of ventricular function after revascularization. 18F-fluorodeoxyglucose single-photon emission computed tomography vs low-dose dobutamine echocardiography.
AIMS: To compare assessment of myocardial flow and glucose metabolism by single-photon emission computed tomography (SPECT) with low-dose dobutamine echocardiography in predicting improvement in regional and global left ventricular function after coronary artery bypass grafting. METHODS AND RESULTS: Thirty patients with regional wall motion abnormalities (mean ejection fraction 32 +/- 19%) were studied with low-dose dobutamine echocardiography (5 and 10 micrograms. kg-1 min-1) and thallium-201/ 18F-fluorodeoxyglucose(FDG) SPECT prior to surgery. For comparative analysis, a 13-segment model was used. Postoperative improvement was predicted if the echocardiogram showed that wall motion abnormalities were reversible during the dobutamine infusion and there was normal perfusion or relatively increased FDG uptake in perfusion defects (mismatch) in dyssynergic segments on SPECT. After surgery, ventricular function was reassessed. An echocardiogram was taken at the 3 month follow-up with the patient at rest. Regional wall motion had improved in 62/168 (37%) revascularized segments. In predicting functional outcome, low-dose dobutamine echocardiography reached a sensitivity of 89% and a specificity of 82%, with a positive predictive value of 74% and a negative predictive value of 93%, whereas for thallium-201/FDG SPECT these values were 84%, 86%, 78% and 90%, respectively. In patients with more than two viable segments on either technique, the wall motion score index, a surrogate of global ventricular function, improved significantly. CONCLUSION: For the optimal prediction of functional outcome, combined assessment of flow and FDG imaging is needed. Both thallium-201/FDG SPECT and low-dose dobutamine echocardiography appear comparable and similarly accurate in predicting improvement of left ventricular function after surgical revascularization.
Analysis of Variance↗
Evaluation of heart-to-organ ratios of 123I-BMIPP and the dimethyl-substituted 123I-DMIPP fatty acid analogue in humans.
Radioiodinated fatty acid analogues modified by methyl-substitution are used for single photon emission tomography (SPET) imaging of the heart. The effect of mono- and dimethyl-substitution on heart-to-organ ratios was investigated in humans to evaluate their relative merits for SPET image quality. Planar total body scans were performed in fasting patients with coronary artery disease, but without heart failure, 1 h after administration of 111 MBq 15-(p-[I-123]-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP, n = 7) or 111 MBq 15-(p-[I-123]-iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPP, n = 4). Because these branched fatty acids are used for cardiac imaging, we focused on heart-to-organ (heart/organ) ratios by comparing small regions of interest in heart, liver, lung, muscle and bladder. Both tracers showed good visualization of the heart. DMIPP showed a relatively high liver uptake: the heart/liver ratios for DMIPP and BMIPP were 0.39 +/- 0.05 and 1.00 +/- 0.12, respectively (P < 0.0001). Increased lung activity was found for BMIPP, with a heart/lung ratio of 1.63 +/- 0.17 versus 2.32 +/- 0.28 for DMIPP (P < 0.001). In contrast to DMIPP, BMIPP also showed increased activity in the bladder. In conclusion, BMIPP and DMIPP show different distribution patterns. Despite the more favourable heart/lung ratios for DMIPP, the high liver uptake affects cardiac SPET image quality and therefore BMIPP appears to provide superior cardiac SPET image quality in humans.
Blood Glucose↗
Detection of myocardial viability with F-18-fluorodeoxyglucose and single photon emission computed tomography.
The application of 18-F-fluorodeoxyglucose (FDG) imaging with single photon emission computed tomography (SPECT) to detect tissue viability has been introduced recently in several centers, both in Europe and the USA. This paper summarizes the available data on FDG SPECT. Three studies have performed a direct comparison between FDG SPECT and FDG PET, showing good agreement between these techniques. Preliminary data in patients with poor left ventricular function undergoing revascularization suggest that FDG SPECT can predict improvement of ventricular function after revascularization. Comparative studies between FDG SPECT and low-dose dobutamine echocardiography also showed close agreement. Although the initial results are promising, larger studies are needed to determine the precise role of FDG SPECT in the assessment of myocardial viability.
Cardiotonic Agents↗
Course of impaired left ventricular function after acute myocardial infarction predicted with planar thallium-201 chloride and F18-fluorodeoxyglucose imaging.
UNLABELLED: Planar reset myocardial thallium-201 chloride (201Tl)/F18-fluorodeoxyglucose (FDG) imaging has been shown to distinguish between viable and non-viable tissue. Twenty-five patients (60 +/- 9 years) with acute myocardial infarction were studied using this technique within 6 +/- 2 days (T1) after infarction and again after 42 +/- 4 days (T6). Serial assessment of wall motion with 2D-echocardiography was performed to determine the predictive value of radionuclide indices for the course of impaired regional left ventricular function. No revascularization procedure was performed. Segmental 201Tl and FDG uptake was evaluated using circumferential profiles. Echocardiographic wall motion was scored as normal, hypokinetic or akinetic. Myocardial segments were considered non-viable if a match between 201Tl and FDG uptake was present, which is a concordant reduction in 201 Tl and FDG uptake (Group A). Myocardial segments were considered viable if: a mismatch was present between 201Tl and FDG uptake which was defined as a segmental FDG uptake exceeding 201Tl uptake by > or = 20% in a segment with reduced 201Tl uptake (Group B); a normal FDG uptake (> or = 75%) was present without a mismatch pattern in a segment with reduced 201Tl uptake (201Tl < 75% of peak activity) (Group C); a normal 201Tl uptake was present in the area of wall motion abnormality (Group D). Corresponding scintigraphic images obtained at T1 and T6 were compared. RESULTS: 51 segments were normokinetic, 37 were hypokinetic and 6 were akinetic at T1. Of the 63 segments with wall motion abnormalities at T1, 18 regions showed a match (FDG-201Tl < 20%) (Group A). Regional function improved in only one (6%) of these segments. In 19 regions a mismatch was present (FDG-201Tl > 20%) (Group B) of which three (16%) showed spontaneous improvement in function (p = NS vs. matched segments), although recovery varied considerably among patients. Regional function in two segments deteriorated. In 14 regions with reduced 201Tl uptake, FDG uptake was normal (Group C) of which five (36%) were improved after 6 weeks (p < 0.05 vs. match; p = NS vs. mismatched segments). Of the 12 segments with normal 201Tl uptake (Group D), seven (58%) showed improvement in function, whereas five (42%) did not show improvement (p < 0.05 vs. match). In addition, all scintigraphically selected viable segments were grouped (Group B + C + D) and compared with the non-viable segments (Group A). The predictive value of a positive viability test for spontaneous functional improvement was 33%. The predictive value of a negative viability test for lack of functional improvement was 94%. CONCLUSIONS: absence of residual FDG uptake shortly after infarction is associated with irreversible injury, while preservation of metabolic activity identifies segments with variable outcome. Wall motion alone is not a good indicator for the presence of viable tissue. Planar 201Tl/FDG imaging allows early identification of viable but jeopardized tissue and may help select patients who will benefit from aggressive therapy to salvage endangered myocardium.
Deoxyglucose↗
Absorbed dose distribution of the auger emitters 67GA and 125I and the beta-emitters 67CU, 90Y, 131I, and 186RE as a function of tumor size, uptake, and intracellular distribution.
PURPOSE: The influence of tumor volume, uptake of radioactive compounds in cells of tumors and normal tissues, and characteristics of the emitted ionizing particles on the efficacy of systemic radiation were studied. METHODS AND MATERIALS: The influence of these variables was assessed using a point kernel approach combined with a distance histogram technique. Simulation calculations were performed to assess dose distributions for three tumor sizes (phi = 200 microns, 2 mm, or 2 cm) and six radionuclides: 67Ga, 125I, 67Cu, 90Y, 131I, and 186Re. RESULTS: The energy deposition patterns depended on the relation of the tumor size and range of the emitted particles. Selective uptake was especially important in cases where the range was short compared to the dimension of the tumor. CONCLUSION: To attain a high dose for treatment of micrometastases, the use of Auger and conversion electron emitters (67Ga and 125I) or beta-emitters with emission spectra including low energetic electrons (67Cu and 131I) was recommended. The results demonstrated the complementary nature of selectivity of energy deposition and crossfire. This implied that for tumor cells or areas with reduced uptake, crossfire from radioactivity in surrounding cells or areas with selective uptake would be provided by intermediate (conversion electrons) or long-range (beta-particles) emissions.
Dose-Response Relationship, Radiation↗
Prediction of recovery of myocardial dysfunction after revascularization. Comparison of fluorine-18 fluorodeoxyglucose/thallium-201 SPECT, thallium-201 stress-reinjection SPECT and dobutamine echocardiography.
OBJECTIVES: We compared three techniques to predict functional recovery after revascularization. BACKGROUND: Recently, fluorine-18 (F-18) fluorodeoxyglucose in combination with single-photon emission computed tomography (SPECT) has been proposed to identify viable myocardium, Thallium-201 reinjection and low dose dobutamine echocardiography are used routinely for this purpose. METHODS: Seventeen patients (mean [+/- SD] left ventricular ejection fraction 36 +/- 11%) were studied. Regional and global ventricular function were evaluated before and 3 months after revascularization by echocardiography and radionuclide ventriculography, respectively. Myocardial F-18 fluorodeoxyglucose uptake (during hyperinsulinemic glucose clamping) was compared with rest perfusion assessed with early thallium-201 SPECT. On a separate day, low dose dobutamine echocardiography and post-stress thallium-201 reinjection SPECT were simultaneously performed. RESULTS: The sensitivities for F-18 fluorodeoxyglucose/thallium-201, thallium-201 reinjection and low dose dobutamine echocardiography to assess recovery were 89%, 93% and 85%, respectively; specificities were 77%, 43% and 63%, respectively. Stepwise logistic regression indicated that F-18 fluorodeoxyglucose/ thallium-201 was the best predictor. In hypokinetic segments, the combination of F-18 fluorodeoxyglucose/thallium-201 and low dose dobutamine echocardiography was the best predictor. Global function improved (left ventricular ejection fraction increased > 5%) in 6 patients and remained unchanged in 11. All three techniques correctly identified five of six patients with improvement. Fluorine-18 fluorodeoxyglucose/thallium-201 identified all patients without improvement; low dose dobutamine echocardiography identified 9 of 11 without improvement; and thallium-201 reinjection identified 6 of 11 patients without improvement. CONCLUSIONS: Fluorine-18 fluorodeoxyglucose/thallium-201 SPECT was superior to the other techniques in assessing functional recovery. Integration of metabolic and functional data is necessary, particularly in hypokinesia, for optimal prediction of improvement of regional function.
Adult↗
Dual X-ray absorptiometry for alveolar bone: precision of peri-implant mineral measurements ex vivo.
The precision of measurements of minor mineral changes in alveolar bone mineral content (ABMC) and alveolar bone mineral density (ABMD) on implant surfaces was determined in small regions (0.03 +/- 0.005 cm2) using dual X-ray absorptiometry (DXA). Dog hemimandibles with alveolar processes containing 17 implants were studied ex vivo. The precision was expressed as the coefficient of variation in percent (c.v. %). The ultra-high resolution protocol was applied to the mesial, distal and apical subregions of each implant. The line spacing was 0.0254 cm and the point resolution was 0.0127 cm. The mean c.v. (%) +/- s.d. for the ABMC in the mesial, distal and apical regions were 0.42 +/- 17, 0.47 +/- 0.21 and 0.48 +/- 0.18, respectively. For the ABMD these values were 0.42 +/- 0.16, 0.47 +/- 0.19 and 0.48 +/- 0.16. For each region approximately 68% of the 17 c.v. values were distributed within 1 s.d. from the mean c.v. These results indicate that measurements are highly reproducible (better than 0.48%) and that there are no differences in precision between several peri-implant regions. Changes as small as 0.85% in ABMC and ABMD in small areas adjacent to implant surfaces are measurable with a confidence level of 95%. Therefore the DXA technique will be expedient for our research evaluating the efficacy of the ceramic hydroxyapatite implant releasing agents affecting or inducing alveolar bone- and root cementum-like materials on its surface.
Absorptiometry, Photon↗