Intravenous streptokinase in acute myocardial infarction (I.S.A.M.) trial: serial evaluation of left ventricular function up to 3 years after infarction estimated by radionuclide ventriculography. I.S.A.M. Study Group.

The Intravenous Streptokinase in Acute Myocardial Infarction (I.S.A.M.) trial was a prospective, placebo-controlled, double-blind multicenter trial of high-dose short-term intravenous streptokinase in acute myocardial infarction administered within 6 h after the onset of symptoms. Global and regional left ventricular ejection fractions were determined by radionuclide ventriculography in a subset of 120 patients 3 days, 4 weeks, 7 months, 18 months and 3 years after acute myocardial infarction. In patients with anterior myocardial infarction, left ventricular ejection fraction was higher in the streptokinase than in the placebo group 3 days after acute infarction (49 +/- 14% vs. 40 +/- 11%, p = 0.02). This difference of about 10% units in ejection fraction persisted during the 3 year follow-up period. Among streptokinase-treated patients, regional left ventricular ejection fraction was higher within the infarct zone as well as in remote myocardium throughout the follow-up period. Among patients with inferior infarction, no significant differences between the treatment and control groups were demonstrable with respect to global and regional left ventricular ejection fraction. Thus, intravenous administration of streptokinase within 6 h after the onset of symptoms of acute myocardial infarction preserves left ventricular function over a period of greater than or equal to 3 years in patients with acute anterior myocardial infarction. It improves regional myocardial function within the infarct zone as well as in remote areas. In patients with acute inferior myocardial infarction, benefit from intravenous streptokinase is of only minor degree.

Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography.

OBJECTIVES: The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction. BACKGROUND: Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability. METHODS: Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 micrograms/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative short-axis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion by left ventriculography. RESULTS: Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean +/- SD 45 +/- 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 +/- 11%). CONCLUSIONS: Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.

Dobutamine magnetic resonance imaging predicts contractile recovery of chronically dysfunctional myocardium after successful revascularization.

OBJECTIVES: This study sought to evaluate whether myocardial viability, as assessed by magnetic resonance imaging (MRI), reliably predicts postrevascularization left ventricular (LV) recovery. BACKGROUND: Compared with positron emission tomographic findings, MRI has proved to be a reliable technique for the identification of residual myocardial viability. However, the predictive accuracy of MRI-assessed preserved end-diastolic wall thickness (DWT) and dobutamine-induced systolic wall thickening (SWT) for LV functional recovery has not yet been evaluated. METHODS: Rest and low dose dobutamine MRI was performed in 43 patients with a chronic infarct (> or =4 months since ischemic event) and LV dysfunction who had undergone revascularization of the infarct-related vessel. On the basis of segmental evaluation of corresponding short-axis tomograms, infarct regions were graded viable by MRI if 1) DWT was > or =5.5 mm, and 2) dobutamine-induced SWT was > or =2 mm in > or =50% of dysfunctional segments related to the infarct region. Functional recovery was defined as SWT > or =2 mm in > or =50% of infarct-related segments at rest 4 to 6 months after successful revascularization. RESULTS: Recovery of regional SWT could be observed in 27 (63%) of 43 patients. Comparison MRI grading before and after revascularization indicated that dobutamine-induced SWT was a better predictor of LV functional recovery (sensitivity 89%, specificity 94%) than was preserved DWT (sensitivity 92%, specificity 56%). Segments that remained akinetic after revascularization had significantly lower DWT (6.0+/-3.1 mm [n = 219] vs. 9.8+/-2.6 mm [n = 188], p < 0.001) than those with improved SWT. Left ventricular ejection fraction increased significantly in patients with dobutamine-induced SWT than in those with no contractile reserve (14+/-9% vs. 3+/-9%, p < 0.0002), and the magnitude of this increase was correlated with the number of dobutamine-responsive segments per infarct region (r = 0.68, p < 0.0001). CONCLUSIONS: Quantitative assessment of dobutamine-induced SWT in chronic infarcts by MRI is a highly accurate predictor of LV functional recovery, and the presence of significantly reduced DWT reliably indicates irreversible myocardial damage. Therefore, dobutamine stress testing for the assessment of myocardial viability can be restricted to patients with preserved DWT.

Improvement of myocardial blood flow to ischemic regions by angiotensin-converting enzyme inhibition with quinaprilat IV: a study using [15O] water dobutamine stress positron emission tomography.

OBJECTIVES: This study was designed to analyze the effects of acute angiotensin-converting enzyme (ACE) inhibition on myocardial blood flow (MBF) in control and ischemic regions. BACKGROUND: Although animal studies indicate an improvement of MBF to ischemic regions after ACE inhibition, this effect has not been conclusively demonstrated in patients with coronary artery disease. METHODS: Myocardial blood flow was analyzed in ischemic and nonischemic regions of 10 symptomatic patients with coronary artery disease using repetitive [15O] water positron emission tomography at rest and during maximal dobutamine stress before and after ACE inhibition with quinaprilat 10 mg i.v. To exclude the possibility that repetitive ischemia may cause an increase in MBF, eight patients underwent the same protocol without quinaprilat (placebo patients). RESULTS: Rate pressure product in control and quinaprilat patients was comparable. In placebo patients, repetitive dobutamine stress did not change MBF to ischemic regions (1.41 +/- 0.17 during the first stress vs. 1.39 +/- 0.19 ml/min/g during the second stress, p = 0.93). In contrast, MBF in ischemic regions increased significantly after acute ACE inhibition with quinaprilat during repetitive dobutamine stress (1.10 +/- 0.13 vs. 1.69 +/- 0.17 ml/min/g, p < 0.015). Dobutamine coronary reserve in ischemic regions remained unchanged in placebo patients (1.07 +/- 0.11 vs. 1.10 +/- 0.16, p = 0.92), but increased significantly after quinaprilat (0.97 +/- 0.10 vs. 1.44 +/- 0.14, p < 0.002). Total coronary resistance decreased after ACE inhibition (123 +/- 19 vs. 71 +/- 10 mm Hg x min x g/ml, p < 0.02). CONCLUSIONS: Angiotensin-converting enzyme inhibition by quinaprilat significantly improves MBF to ischemic regions in patients with coronary artery disease.

Significance of rest technetium-99m sestamibi imaging for the prediction of improvement of left ventricular dysfunction after Q wave myocardial infarction: importance of infarct location adjusted thresholds.

OBJECTIVE: The value of rest technetium-99m (Tc-99m) sestamibi scintigraphy under oral nitrate medication to predict myocardial viability was examined in patients with chronic infarcts. BACKGROUND: The value of rest Tc-99m sestamibi to predict viability in infarct regions has not been fully established because significant underestimation of viability, especially in the inferior myocardial wall, has been reported. METHODS: Forty patients with Q wave myocardial infarction underwent Tc-99m sestamibi single-photon emission computed tomography under nitrate medication before revascularization of the infarct-related artery. Wall motion was quantified from paired angiograms before and 4 months after revascularization. Tracer uptake was quantified in the central infarct region identified on the angiogram. RESULTS: The average Tc-99m sestamibi uptake in the central infarct region of patients with anterior infarcts and improvement of left ventricular function was significantly higher (68+/-12%, mean+/-SD) than in patients without improvement of function (40+/-14%, p < 0.02). The average Tc-99m sestamibi uptake in the central infarct region of patients with improvement of function and inferior infarcts was significantly lower (43+/-7%) than in patients with anterior infarcts (68+/-12%, p < 0.003), but was significantly higher than in patients with inferior infarction and no improvement of function (31+/-7%, p < 0.02). Using an infarct location adjusted optimal threshold (50% for anterior infarcts, 35% for inferior infarcts), Tc-99m sestamibi had a positive predictive value of 90% and a negative predictive value of 91% for improvement of left ventricular function. CONCLUSION: Quantitative rest Tc-99m sestamibi scintigraphy after oral nitrates reliably predicts improvement of left ventricular function after revascularization if infarct location adjusted thresholds are used.

Predictive value of low dose dobutamine transesophageal echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography for recovery of regional left ventricular function after successful revascularization.

OBJECTIVES: This study was designed to assess the predictive value of myocardial viability diagnosed by dobutamine transesophageal echocardiography and fluorine (F)-18 fluorodeoxyglucose positron emission tomography for left ventricular functional recovery after revascularization in patients with chronic left ventricular dysfunction. BACKGROUND: The identification of akinetic but viable myocardium is of particular importance for the selection of patients with a compromised left ventricle who will benefit from coronary revascularization. METHODS: Multiplane rest and dobutamine transesophageal echocardiography (dobutamine, 5 and 10 microg/min per kg) studies and F-18 fluorodeoxyglucose positron emission tomographic studies at rest were performed in 2 patients with 1) previous myocardial infarction and regional akinesia, 2) a stenosed infarct-related coronary artery, and 3) a patent infarct-related vessel after revascularization. A basally akinetic segment was considered viable by transesophageal echocardiography if dobutamine-induced contractile reserve could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion. Recovery of regional left ventricular function 4 to 6 months after revascularization was diagnosed by transesophageal echocardiography if > or = 50% of segments akinetic at baseline had improved wall thickening. RESULTS: Dobutamine transesophageal echocardiography identified viable infarct regions in 25 (59%) of 42 patients, and F-18 fluorodeoxyglucose positron emission tomography in 30 (71%) of 42 patients, yielding diagnostic agreement in 86% of patients. Sensitivity and specificity for prediction of left ventricular functional recovery in individual patients was 92% and 88%, respectively, for dobutamine transesophageal echocardiography versus 96% and 69% for F-18 fluorodeoxyglucose positron emission tomography. Segments remaining akinetic after revascularization had a significantly lower (p < 0.001) F-18 fluorodeoxyglucose uptake (48 +/- 15%) than that (73 +/- 15%) of segments with recovery of regional left ventricular function. CONCLUSIONS: Both dobutamine transesophageal echocardiography and F-18 fluorodeoxyglucose positron emission tomography were highly sensitive in predicting functional recovery of chronically kinetic or dyskinetic myocardium after successful revascularization. Thus, dobutamine transesophageal echocardiography is a clinically valuable alternative to F-18 fluorodeoxyglucose positron emission tomography for assessing residual viability and predicting functional recovery after revascularization.

Dipyridamole scintigraphy and intravascular ultrasound after successful coronary intervention.

UNLABELLED: Despite angiographically successful interventions, perfusion defects are not uncommonly observed in postinterventional perfusion scintigrams. The aim of this study was to test the hypothesis that perfusion defects after coronary intervention are associated with a significant residual stenosis in the treated vessel segment detectable by intravascular ultrasound but not by angiography. METHODS: Forty consecutive patients with angiographically successful coronary interventions were prospectively studied by intravascular ultrasound immediately after the intervention. Within 48 hr after the intervention all patients had myocardial scintigraphy using 99mTc-methoxyisobutyl-isonitrile SPECT after dipyridamole stress. Myocardial perfusion defects in the scintigram were assigned to a segmental left ventricular model and compared to the perfusion territory of the treated vessel estimated from the coronary angiogram. RESULTS: Twenty of 40 patients had reversible myocardial perfusion defects. Mean ultrasound area stenosis was 50% in these patients and 33% in patients without perfusion defects (p < 0.002); ultrasound percent plaque area was 75% versus 63% (p < 0.0001), respectively. The best concordance between residual area stenosis and perfusion defects was found for an ultrasound area stenosis > or = 40%. CONCLUSION: Patients with stress-induced myocardial perfusion defects immediately after successful coronary intervention show high-grade residual stenoses that are more pronounced in patients with perfusion defects than in patients with normal postinterventional scintigrams. In addition, vessels serving myocardial regions with perfusion defects showed a significantly higher plaque burden indicating diffuse atherosclerotic changes in the vessel. The evaluation of the postprocedural result by intravascular ultrasound contributes to a better understanding of the discrepancy between the angiographic finding of a widely patent vessel but scintigraphic evidence of impaired perfusion.

Morphologic correlate of pathologic Q waves as assessed by gradient-echo magnetic resonance imaging.

To assess the morphologic correlate of the presence and absence of pathologic Q waves in the electrocardiogram, 30 patients with and 17 patients without pathologic Q waves and chronic myocardial infarction (infarct age > 4 months) and 15 patients without previous myocardial infarction but significant coronary artery disease (> 70% diameter stenoses) were studied by gradient-echo magnetic resonance imaging (MRI). Short-axis MRI tomograms were evaluated on a segmental basis by calculating end-diastolic wall thickness and systolic wall thickening. All segments were graded transmural scar (end-diastolic wall thickness < end-diastolic wall thickness of a healthy control group [n = 21]-2.5 SD and lack of systolic wall thickening), hypokinetic (end-diastolic wall thickness > or = end-diastolic wall thickness of the control group-2.5 SD and systolic wall thickening < or = 2 mm), or normal (end-diastolic wall thickness > or = end-diastolic wall thickness of the control group-2.5 SD and systolic wall thickening > 2 mm) by MRI criteria. Myocardial infarcts were defined as transmural if at least 1 segment fulfilled the MRI criteria for transmural scar. Of 30 patients with Q-wave infarction, 26 (87%) had a transmural defect, and 6 of 17 patients (35%) with non-Q-wave infarction had a transmural infarct. Segmental evaluation yielded 129 of 480 scar segments (27%) for patients with Q-wave infarction, 20 of 272 scar segments (7%) for patients with non-Q-wave infarction, and no scar segments for patients without previous myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Recanalization of chronic total coronary arterial occlusions by percutaneous excimer-laser and laser-assisted angioplasty.

A low primary success and high restenosis rate after recanalization of chronic total occlusions by conventional coronary angioplasty have encouraged the application of new interventional techniques like excimer-laser angioplasty. In 39 patients with a coronary occlusion for 1 to 12 months, recanalization was attempted by laser angioplasty through a multifiber-catheter coupled to a pulsed XeCl excimer laser. After successful passage of the occlusion by a standard guidewire in 27 patients (69%), the laser catheter was advanced over the central guidewire and crossed the occlusion in 25 patients (64%). In 2 patients with unsuccessful passage of the laser catheter, the subsequent attempt with a low profile balloon catheter also failed. In 19 of the 25 patients with successful laser recanalization, the residual stenosis exceeded 50% and was therefore followed by additional balloon angioplasty. The average residual stenosis after laser was 61 +/- 17% of the vessel diameter, and after balloon angioplasty 28 +/- 9% (n = 19), whereas after laser angioplasty alone it was 38 +/- 5% (n = 6). No complications associated with the laser application were observed. Angiographic control after 24 hours showed a reocclusion of 2 (8%) recanalized vessels. In this pilot study, laser angioplasty proved to be a safe and feasible method for the treatment of chronic total coronary occlusions. Because it was necessary to guide the catheter by a central wire, the primary success was limited by a successful passage of the wire of the occlusion. The rate of stand-alone laser angioplasty has to be increased by future improvements of the technique to enable a comparative evaluation of this method with conventional angioplasty.

Comparison of dobutamine transesophageal echocardiography and dobutamine magnetic resonance imaging for detection of residual myocardial viability.

A dobutamine-induced contraction reserve in akinetic but viable myocardium, observed by echocardiography or magnetic resonance imaging (MRI), is a reliable indicator of myocardial viability. However, the comparative diagnostic accuracy of these 2 techniques is unknown. Therefore, 43 patients with myocardial infarction (infarct age > or = 4 months) and regional akinesia underwent dobutamine transesophageal echocardiography (TEE) and dobutamine MRI (10 microg dobutamine/ min/kg). Both imaging techniques were compared with the reference standard 18F-fluorodeoxyglucose positron emission tomography (FDG PET). An infarct region was considered viable if a dobutamine contraction reserve could be assessed visually by TEE or quantitatively by MRI in > or = 50% of segments graded "a" or dyskinetic at rest. Infarct regions were graded viable by PET if FDG uptake was > or = 50% of the maximal FDG uptake in a region with normal wall motion by left ventriculography. A dobutamine contraction reserve was found in 21 of 43 patients (49%) by TEE and MRI. A viable infarct region by FDG PET was diagnosed in 26 of 43 patients (60%). FDG uptake and dobutamine TEE were concordant in 36 of 43 patients (84%) and dobutamine MRI and FDG PET were concordant in 38 of 43 patients (88%). Sensitivity and specificity of dobutamine TEE and dobutamine MRI for FDG PET-defined myocardial viability were 77% versus 81% and 94% versus 100%, respectively. Both imaging techniques yielded similar results for the detection of myocardial viability as defined by FDG uptake, with a slightly higher sensitivity and specificity for the quantitatively evaluated dobutamine contraction reserve by MRI.

Technetium 99m-MIBI-SPECT: A highly sensitive diagnostic tool for localization of parathyroid adenomas.

BACKGROUND: The aim of this study was to assess the value of technetium 99m-MIBI scintigraphy using the single photon emission computed tomography (SPECT) technique for preoperative localization of smaller (

Kinetics of melphalan leakage during hyperthermic isolation perfusion in melanoma of the limb.

The kinetics of melphalan leakage into the peripheral blood were studied in 21 patients undergoing hyperthermic isolation perfusion of the upper or lower limb as an adjuvant treatment in high-risk melanoma; in 5 patients cisplatin was added. The melphalan concentrations in the peripheral blood rose predominantly during the first 20 min of perfusion and levelled out to an apparent steady state of about 0.28 micrograms/ml in upper extremity perfusions, and 0.34 (without cisplatin) and 0.37 micrograms/ml (with cisplatin) in lower extremity perfusion. Erythrocytes labelled with technetium Tc 99m, which were added concomitantly with melphalan to the perfusion medium, appeared in the systemic circulation of the patients at an almost constant rate of 0.32% (lower and upper limb perfusions without cisplatin and 0.37% (with cisplatin) of total tracer/min. This perfusate flow rate indicated by labelled erythrocytes completely explained the leakage of melphalan from the perfusion circuit into the peripheral blood. Peak concentrations of melphalan in the peripheral blood were observed immediately after reconstitution of normal hemodynamic conditions once isolation perfusion had been terminated. This fraction of melphalan might originate from tissue-binding sites, but also from vascular compartments; therefore, a thorough washing-out procedure might minimize this effect.

99mTc-hexamethylpropylene amine oxime SPECT and X-ray CT in acute cerebral ischaemia.

Early diagnosis of acute cerebral ischaemia is still unsatisfactory, because X-ray computed tomography (CT) does not reveal the site and extent of hypoperfusion within the first 24 h. Single photon emission computed tomography (SPECT) using 99mTc-hexamethylpropylene amine oxime (HMPAO) may offer earlier information, since the distribution of HMPAO follows the actual cerebral perfusion pattern. We therefore investigated 53 patients suffering from acute cerebral ischaemia (10 with transient ischaemic attacks, 9 with prolonged ischaemic reversible neurological deficits, 34 with completed stroke). SPECT and CT examinations were performed on days 1, 3, and 14. On day 1, SPECT revealed hypoperfused areas in 42 patients, whereas CT showed hypodensities only in 5. The sensitivity of SPECT was higher in cortical compared with subcortical ischaemia. In patients suffering from reversible neurological deficits SPECT normalized in the follow-up, corresponding to clinical improvement. In completed stroke, SPECT demonstrated variable perfusion patterns with hypo-, normo-, and hypoperfused areas on day 3 and especially on day 14. In contrast to CT, HMPAO SPECT leads to early diagnosis of cerebral ischaemia, in particular within the cerebral cortex.

The development of an epileptogenic focus. A case study with 99mTc-HMPAO SPECT.

A patient is described who developed complex partial seizures with secondary generalization 3 years after a severe viral encephalitis with a CT and EEG identified lesion in the left insular cortex and its surrounding structures. When the seizures first occurred CT and MRI as well as repeated interictal conventional EEG recordings were entirely normal. Single photon emission computed tomography (SPECT), however, revealed an area of increased 99mTc-hexamethyl propyleneamine oxime (HMPAO) uptake in the left insular cortex. After anticonvulsive therapy the seizures and the SPECT findings disappeared. 99mTc-HMPAO SPECT is a highly sensitive method for the demonstration of functional alterations in brain tissue. It can improve diagnosis of epilepsy and may provide additional information to monitor anticonvulsive therapy.

Safety aspects of transcranial brain stimulation in man tested by single photon emission-computed tomography.

Single photon emission-computed tomography (SPECT) using 99mTc-labelled hexamethylpropyleneamine oxime (99mTc-HMPAO), a new method to visualize regional cerebral blood flow (rCBF) and epileptogenic foci, was used to study acute and long-term effects of transcranial brain stimulation. Magnetic and electric brain stimulation increase rCBF not more than voluntary muscle activation mimicking the motor effects of transcranial brain stimulation. Focal rCBF increase, typical for epileptogenic foci, or other pathological findings could not be detected even when the subject had received several thousand stimulations in the past. Transcranial brain stimulation does not produce rCBF patterns indicating acute or chronic adverse effects.

Hypothyroidism after therapy for larynx and pharynx carcinoma.

Early detection of local and regional recurrence is the main goal during follow-up of patients with larynx and pharynx cancer. Hypothyroidism occurring in those patients stays frequently undiagnosed as screening for hypothyroidism is not part of the routine follow-up. This study was performed to assess the prevalence of hypothyroidism in these patients. We included 120 patients (106 male, 14 female) with larynx or pharynx cancer treated more than 2 months earlier (mean = 41 months) in the study. Cancer treatment consisted of either surgery (n = 44), radiotherapy (n = 15), or surgery combined with postoperative radiotherapy (n = 61). In all patients, thyroid function studies (thyrotropin [TSH], free triiodothyronine [FT3], and free thyroxine [FT4]) were performed. Twenty-six of all patients (22%) were hypothyroid; in two patients hypothyroidism was diagnosed postoperatively and these two patients were on replacement therapy with thyroid hormones. The highest rate of hypothyroidism (34%) was present in patients treated with surgery combined with radiotherapy, whereas among patients treated with surgery only 7% were hypothyroid (p < 0.001). There was no difference in the duration of follow-up between therapy and inclusion in the study between those two groups. Two of 15 patients treated only with radiotherapy were diagnosed hypothyroid, but in this group the latency was shorter (p < 0.05). The results indicate that thyroid function studies should be routinely performed in the follow-up of head and neck cancer patients, especially if radiotherapy was part of the treatment.

Glucose metabolism of the thyroid in Graves' disease measured by F-18-fluoro-deoxyglucose positron emission tomography.

The radiolabeled glucose surrogate F-18-fluoro-deoxyglucose (F-18-FDG) and positron emission tomography (PET) were used to measure glucose metabolism of the thyroid in vivo. We evaluated patients with Graves' disease before therapy with radioiodine in comparison to patients with normal thyroids. Thirty-six patients with Graves' disease underwent scanning the day before radioiodine therapy. Twenty patients with head tumors and normal thyroids were the controls. Overall F-18-FDG uptake was determined for all thyroids and modeling of glucose metabolism was performed in order to differentiate between glucose concentration in the fractional blood volume, glucose transport, and glucose utilization. F-18-FDG uptake was significantly higher in Graves' disease patients compared with controls. In these patients F-18-FDG uptake increased with increasing antithyroid antibodies and shorter radioiodine half-life. Modeling of glucose metabolism revealed substantial differences in thyroid F-18-FDG utilization constants (k3 values) corresponding to enhanced local metabolic rates in Graves' disease. No significant differences in the remaining rate constants and the fractional blood volume were detected. These results indicate that glucose metabolism is enhanced in the thyroid of Graves' disease patients not only due to enhanced fractional blood volume but to enhanced utilization. Whether a lymphocytic infiltration or thyroid epithelial cells utilize this surplus of glucose cannot be determined using in vivo PET measurements in humans. Still, the correlation of radioiodine half-life and glucose hypermetabolism suggests direct or nondirect connections of glucose metabolism and hormone synthesis in thyroid cells.

Glucose metabolism of the thyroid in autonomous goiter measured by F-18-FDG-PE.

The radiolabeled glucose analogue F-18-Fluoro-Deoxyglucose (F-18-FDG) and Positron Emission Tomography (PET) were used to measure glucose metabolism of the thyroid in vivo. We evaluated patients with autonomous goitre before therapy with radioiodine in comparison to patients with normal thyroids. 30 patients with autonomous goitre underwent scanning the day before radioiodine therapy. 19 patients with head or brain tumours and normal thyroids were the controls. Overall F-18-FDG uptake was determined for all thyroids and proved to be significantly higher in autonomy patients compared to controls and in disseminated autonomous goitre slightly but not significantly higher than in focal autonomy. In autonomy patients F-18-FDG uptake increased with increasing radioiodine uptake and shorter radioiodine half-life. These results indicate that glucose metabolism is enhanced in the thyroids of patients with focal and disseminated autonomy. The negative correlation of radioiodine half-life and glucose metabolism as well as the positive correlation of radioiodine uptake and glucose metabolism suggest connections of glucose metabolism and iodine-dependent hormone synthesis in thyroid cells.

[Sonographic determination of thyroid volume--comparison with surgical data]. / Sonographische Bestimmung des Schilddrüsenvolumens--Vergleich mit operativen Daten.

AIM: Objective of this prospective study was to find out, if especially the volume of large nodular goitres can be determined accurately by using ultrasonography and the ellipsoid model. METHODS: 100 patients with different thyroid disorders, who all underwent a thyroid resection, were examined by a single experienced investigator. The preoperative thyroid volume was determined by ultrasonography and correlated to the sum of surgically removed and postoperative thyroid volume determined by ultrasound. RESULTS: Patients included had thyroid volumes between 12 and 450 ml (mean value 89 ml). Within the whole study group, coefficients of correlation and variation were r = 0.90 and CV = 0.29, respectively. The mean difference between the thyroid volume determined preoperatively by ultrasonography and the sum of surgically removed and postoperative thyroid volume was 3 +/- 27 ml or 13 +/- 38%. Excluding patients with retrosternal goitres or cysts with a diameter > 2 cm, the correlation coefficient increased to r = 0.95 (CV = 0.21) and mean differences decreased to 2 +/- 20 ml and 9 +/- 30%. Further subdivision according to thyroid volume (< or = 50 ml, < or = 100 ml, > 100 ml) revealed no significant influence of thyroid volume on the accuracy of ultrasound volume determination. Subdividing the study collective according thyroid disorders, relevant deviations of preoperative sonographic thyroid volume from the sum of surgically removed and postoperative thyroid volume were observed in case of retrosternal goitre (19 +/- 62%), cystic degeneration (41 +/- 52%) and Graves' disease (23 +/- 29%). CONCLUSION: These results show, that even large suprasternal goitres > 100 ml can be sufficiently determined by ultrasound by an experienced examiner.

[Immunogenic hyperthyroidism following radioiodine ablation of a focal autonomy]. / Immunogene Hyperthyreose nach Radiojod-Ablation einer fokalen Autonomie.

Immunogenic hyperthyroidism rarely develops after radioiodine elimination of focal autonomous thyroid tissue. We observed this phenomenon in 8 patients between 1989 and 1992. The occurrence of immunogenic hyperthyroidism shortly after elimination of autonomous nodules has not been studied nor is it properly understood. Most studies known today describe the development of autonomous nodules in the course of immunogenic hyperthyroidism or ignore the chronologic order of occurrence. The possibility that immunogenic hyperthyroidism may occur after radioiodine therapy of autonomous nodules, makes a consequent follow-up within the first year following radioiodine therapy mandatory.