Dobutamine 99mTc-MIBI single-photon emission tomography: non-exercise-dependent detection of haemodynamically significant coronary artery stenoses

Dobutamine pharmacological stress testing in conjunction with technetium-99m methoxyisobutylisonitrile single-photon emission tomography (MIBI SPET) may be a useful alternative to convential exercise stress MIBI SPET for the detection and localisation of coronary artery stenoses. Therefore, 35 patients with stenoses ( 50% diameter reduction) of one or more coronary arteries were selected for dobutamine MIBI SPET. Each patient underwent MIBI injection at rest and during dobutamine infusion with incremental doses (5, 10, 15 and 20 g kg^–1 min^–1). A conventional exercise stress test (EST) was performed in all patients. Peak double product during steady-state dobutamine infusion (18 200 ± 4200 mmHg min^–1) was lower (P = 0.0001) than during EST (21 700 ± 4900 mmHg min^–1). Image quality was good in all but one patient, who had to be excluded from data analysis due to excessive hepatobiliary MIBI activity. Dobutamine-induced perfusion abnormalities were observed in 30/34 MIBI SPET studies, resulting in an overall detection rate for coronary artery disease of 88%. A pathological EST was observed in 23/34 patients (68%). The detection rate of individual coronary artery stenoses was 85% (28/33) for stenosess with a severe diameter reduction (>70%) and 50% (12/24) for stenoses with a moderate diameter reduction ( 50–70%). In particular, sensitivity and specificity for the detection of moderate and severe stenoses ( 50%) were 75%/100% for left anterior descending, 67%/95% for left circumflex and 67%/69% for right coronary artery stenoses. Dobutamine MIBI SPET is a well-tolerated, non-exercise-dependent test for detection and localisation of haemodynamically significant coronary artery stenoses. The use of dobutamine allows a stepwise increase in pharmacological stress similar to EST and is especially useful in patients who are unable to exercise. Correspondence to: E. Voth     

Comparison of iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane and 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane for imaging of the dopamine transporter in the living human brain

Several cocaine congeners are of potential for imaging the dopamine transporter (DAT). Previous studies have shown that iodine-123 labelled 2-carbomethoxy-3-(4-iodophenyl)tropane ([¹²³I]-CIT) is a promising radiotracer for imaging the serotonin (5-HT) and dopamine (DA) transporters in the living human brain with single-photon emission tomography (SPET). [¹²³I]-CIT was found to be not very practical for 1-day DAT imaging protocols since peak DAT uptake occurs later than 8 h. Here we report a pilot comparison of [¹²³I]-CIT and 2-carbomethoxy-3-(4-iodophenyl)-N-(3-fluoropropyl)nortropane ([¹²³I]-CIT FP), using SPET imaging in four healthy male subjects. Peak uptake of [¹²³I]-CIT-FP into the basal ganglia occurred earlier (3–4 h after injection of tracer) than that of [¹²³I]-CIT (>8 h). However, the specific DAT binding of [¹²³I]-CIT-FP in the basal ganglia was somewhat less (0.813±0.047) than that of [¹²³I]-CIT (0.922±0.004). Imaging quality is excellent with both tracers and they are potentially of value for brain imaging in various neuropsychiatric disorders.     

Prognostic value of iodine-123 labelled BMIPP fatty acid analogue imaging in patients with myocardial infarction

This study was undertaken to evaluate the prognostic value of iodine-123 labelled 15-iodophenyl3-R,S-methyl pentadecanoic acid (BMIPP) imaging in patients with myocardial infarction. BMIPP is an iodinated methyl branched fatty acid analogue which is trapped in the myocardium with little washout, thereby reflecting fatty acid utilization in the myocardium. We previously reported that in patients with myocardial infarction, regions are often observed where reduced BMIPP uptake is seen relative to thallium-201 perfusion at rest. However, the clinical significance of such discordant BMIPP uptake remains unknown. Fifty consecutive patients with chronic myocardial infarction referred for stress thallium scan and coronary arteriography underwent BMIPP imaging at rest. Each patient was in a stable condition at the time of the radionuclide study. Follow-up was performed at a mean interval of 23 months to investigate the prognostic implications of the radionuclide studies. Nine patients had cardiac events during the follow-up period. Univariate analysis showed that the number of discordant BMIPP versus²⁰¹TL uptake segments was the best predictor of future cardiac events (P=0.0245), followed by the presence of discordant BMIPP uptake (P=0.0388) and the number of²⁰¹TL redistribution segments (P=0.0444). When all the clinical and radionuclide variables were analysed by Cox regression analysis, the presence of discordant BMIPP uptake was the best, and an independent, predictor of future cardiac events (²=8.5) followed by the number of coronary stenoses on angiography (²=3.9). These preliminary data suggest that decreased BMIPP uptake relative to²⁰¹TL is a valuable predictor of future cardiac events in patients with myocardial infarction. Areas with such discordant BMIPP uptake may contain jeopardized myocardium where fatty acid utilization has been severely suppressed relative to myocardial perfusion.Presented in part at the 40th Annual Meeting of Society of Nuclear Medicine at Orlando, Florida, June 1994     

Three-dimensional display of myocardial perfusion detection of ischemic lesions using a new image subtraction method

A recent, commercially available computer program for the three-dimensional (3D) display of single-photon emission tomography (SPET) data was used to study myocardial perfusion in patients with coronary artery disease (CAD). To enable the detection of small ischemic lesions, the authors proposed a new distance-subtraction method: after suitable centering of the axial slices, 3D distance-shaded images of the stress study were subtracted from the corresponding views of the rest study. With this technique, small changes in surface-to-observer distance were highlighted, thus enabling us to detect nontransmural ischemic areas of the myocardium. General characteristics and possibilities of the subtraction technique were tested on a simple myocardial phantom. Some clinical results of the application of this method on CAD patients are presented and discussed. In CAD patients in whom only nontransmural ischemic lesions are present, the subtraction of distance-shaded images is decisive for a correct diagnosis.     

Evaluation of myocardial function with the 201Thallium scintimetry in various diseases of the heart

To assess the validity of the quantitative ²⁰¹Tl scintimetry in various diseases of the heart (coronary heart disease with and without myocardial infarction, non-coronary cardiomyopathy, scleroderma heart disease and asymmetric septal hypertrophy with IHSS), the ²⁰¹Tl myocardial uptake values for five standardized projections (a) were correlated with the grade of LAD stenosis, (b) the pattern of myocardial wall motion and (c) were compared with the ²⁰¹Tl uptake values derived from normal patients. Significant reduction (c) of ²⁰¹Tl myocardial uptake could in individual cases be evaluated in acute myocardial infarction (95%), in dys-and akinesia (90%), in hypokinesia (71%), in scleroderma heart disease (50%), in non-coronary cardiomyopathy (50%) as well as in normokinesia (28%) when associated with LAD stenosis. The mean values (b) of ²⁰¹Tl uptake in normo-and hypokinesia significantly differed between these two groups and from those evaluated in dys-and akinesia. The latter group showed the lowest ²⁰¹Tl uptake values computed which in some cases were very close to the mean mediastinal ²⁰¹Tl uptake. The correlation (a) of individual ²⁰¹Tl values demonstrated that ²⁰¹Tl distribution in the myocardium is not only equivalent to myocardial perfusion but is corresponding with the myocardial function. In non-coronary cardiomyopathy reduced ²⁰¹Tl values sometimes could not be separated from values in coronary heart disease (and myocardial infarction). A regional increase of myocardial mass as in septal hypertrophy correlated well with an augmented ²⁰¹Tl uptake when referred to the ²⁰¹Tl storage in the mediastinum.Dedicated to Prof. Dr. F.E. Stieve, Berlin, on the occasion of his 60th birthday     

Comparison of thallium-201 single-photon emission tomography after rest injection and fluorodeoxyglucose positron emission tomography for assessment of myocardial viability in patients with chronic coronary artery disease

This prospective study in 42 patients with chronic coronary artery disease and severe wall motion abnormalities (sWMA) on cineventriculography (24 patients with previous myocardial infarction; ejection fraction, 45%±13%) was designed to compare myocardial thallium-201 uptake after rest injection and normalized fluorodeoxyglucose (¹⁸FDG) uptake (after oral glucose load) for assessment of a rest ²⁰¹Tl protocol to evaluate myocardial viability. The left ventricle was divided into the supply territory of the left anterior descending coronary artery (LAD) and the lateral wall and posterior territory (inferior, posterior and posteroseptal segments) because of the high variability of left circumflex and right coronary artery supply territories. Segmental ²⁰¹Tl uptake in single-photon emission tomography (SPET) and segmental normalized ¹⁸FDG uptake (13 segments per patient) showed a close linear relationship in the LAD territory (r=0.79) and in the lateral wall (r=0.77), while the correlation in the posterior territory was considerably lower (r=0.52). ²⁰¹Tl/¹⁸FDG concordance was defined as an ¹⁸FDG uptake exceeding ²⁰¹Tl uptake by < 20%. Discordance was assumed if ¹⁸FDG exceeded ²⁰¹Tl uptake by at least 20%. Concordant results were shown by 81% (439/541) of segments. In segments with severe ²⁰¹Tl reduction ( 50% of peak, n=78) discordance was observed in 10% of segments in the LAD territory and lateral wall (n=62) and in 44% of segments in the posterior territory (n=16). In segments with moderate ²⁰¹Tl reduction (51%–75%, n=205) discordance occured in 12% (LAD and lateral wall, n=126) or 46% (posterior territory, n=79) of segments, respectively. Severe defects were defined as the entire area with ²⁰¹Tl uptake 50% within a defined territory. Discordance was observed in 6/43 (14%) of these. Of 90 areas with sWMA on cineventriculography, 12 showed discordant results. Ten of these 12 discordant areas affected septum or posterior wall. In areas with normal wall motion or only mild hypokinesis, discordance occured in the septum or posterior wall in 22% whereas the figure for the anterior or lateral wall was only 2%. These results point to a significant role of photon attenuation in ²⁰¹Tl SPET imaging in the septum and posterior wall. It is concluded that ²⁰¹Tl SPET using a rest protocol identifies viable myocardium in the supply area of the LAD and in the lateral wall with high accuracy compared to ¹⁸FDG positron emission tomography while disordance in the posterior territory may be governed by photon attenuation in the SPET study rather than by a pathophysiological difference. Correspondence to: C. Aftehoefer     

Practical benefit of [123I]FP-CIT SPET in the demonstration of the dopaminergic deficit in Parkinson's disease

Loss of striatal dopamine (DA) transporters in Parkinson's disease (PD) has been accurately assessed in vivo by single-photon emission tomography (SPET) studies using [¹²³I]-CIT. However, these studies have also shown that adequate imaging of the striatal DA transporter content can be performed only 20–30 h following the injection of [¹²³I]-CIT, which is not convenient for routine out-patient evaluations. Recently, a new ligand,N--fluoropropyl-2-carbomethoxy-3-(4-iodophenyl)tropane (FP-CIT), became available for in vivo imaging of the DA transporter. The faster kinetics of [¹²³I]FP-CIT have been shown to allow adequate acquisition as early as 3 h following injection. In the present study, loss of striatal DA transporters in five non-medicated PD patients was assessed on two consecutive SPET scans, one with [¹²³I]-CIT (24 h following injection) and one with [¹²³I]FP-CIT (3 h following injection). The ratios of specific to non-specific [¹²³I]FP-CIT uptake in the caudate nucleus and putamen were consistently 2.5-fold lower than those of [¹²³I]-CIT. However, when the uptake ratio of both ligands in these brain regions of patients was expressed as a percentage of the uptake ratio found in healthy controls, both the decrease and the variation of the data were similar. It is concluded on the basis of these findings that [¹²³I]FP-CIT seems as good as [¹²³I]-CIT for the assessment of the dopaminergic deficit in PD. The faster kinetics of [¹²³I]FP-CIT are a clear advantage.     

The “dural tail” adjacent to meningiomas studied by dynamic contrast-enhanced MRI: a comparison with histopathology

We examined 32 patients with intracranial tumors (17 meningiomas, 8 neuromas, 7 pituitary adenomas) by conventional and dynamic contrast-enhanced MRI. Our aim was to clarify whether the pathological dural contrast enhancement adjacent to meningiomas (the dural tail) is specific to meningiomas and, more important, whether it represents neoplastic dural infiltration or hypervascularization as a tumor accompanying reaction. A dural tail was found in 9 of 17 meningiomas. None of the other extra-axial tumours (neuromas, pituitary adenomas) showed comparable dural enhancement. Dynamic examinations with an ultrafast single slice imaging technique (snapshot-FLASH) after a bolus injection of contrast medium showed a dural tail in seven out of these nine meningiomas, while in two cases the dural tail turned out to be a cortical vein with a characteristic dynamic contrast enhancement pattern. In the dynamic study all seven dural tails were found to have earlier, steeper contrast enhancement than the corresponding tumours. All the tumours and part of the adjacent dura mater in four of the seven meningiomas with dural enhancement were examined histopathologically. In none of these four cases was neoplastic tissue found more than 2 mm away from the main tumour. The results strongly support the suggestion that the dural tail adjacent to meningiomas represents a hypervascular, non-neoplastic dural reaction.     

Reverse redistribution of thallium-201 represents a low-risk finding in thrombolysed patients following myocardial infarction

The aim of the study was to evaluate the prevalence and clinical significance of reverse redistribution on thallium-201 imaging in post-myocardial infarction patients who have undergone thrombolytic therapy. Sixty-two patients aged 35–79 (mean 60) years with proven myocardial infarction who had undergone thrombolysis were studied 6 weeks post infarction. Standard stress and 4-h redistribution imaging was performed with ²⁰¹Tl following treadmill exercise. Separate day rest injection of ²⁰¹T1 was given after sublingual nitroglycerine; imaging was performed at 1 h. Planar images were acquired in three standard views and semiquantitative segmental analysis of the images was performed from the unprocessed images. All patients had radionuclide ventriculography for the assessment of left ventricular ejection fraction and wall motion abnormality. Thirty-three patients also had coronary angiography. ²⁰¹T1 scintigraphy revealed fixed defects in 19 patients, reversible defects in 22, and reverse redistribution in 21. Those with reverse redistribution had a significantly higher exercise capacity (P < 0.01). Mean (SD) left ventricular ejection fraction was 46 (12)% for those with fixed defects, 47 (9)% for those with reversible defects and 45 (15)% for patients with reverse redistribution (P = NS). The regional wall motion abnormality score was 8 (5), 11.8 (2.2) and 14.2 (6) respectively in patients with reverse redistribution, redistribution alone and fixed defects. Regions with reverse redistribution revealed less regional wall motion abnormality compared to the other two groups (P < 0.01). Fifteen patients demonstrated significant ²⁰¹Tl uptake in the region showing reverse redistribution, with rest injection of ²⁰¹Tl following sublingual nitroglycerine, suggesting viable myocardium in that region. Patients with reverse redistribution had less residual stenosis of the infarct-related artery than those with fixed or reversible defects. Reverse redistribution on ²⁰¹T1 scintigraphy is a common phenomenon, even at 6 weeks, in patients with myocardial infarction who have received thrombolytic therapy. Areas with reverse redistribution demonstrate ²⁰¹T1 uptake following rest injection, less regional wall motion abnormality and a more patent infarct-related artery. Thus, reverse redistribution in these patients represents a low risk finding which suggests retained myocardial viability and successful thrombolytic therapy.     

Sodium bicarbonate-augmented stress thallium myocardial scintigraphy

It is well known that sodium bicarbonate in pharmacological doses induces transient alkalosis, causing intracellular transport of serum potassium. The aims of this study were (a) to investigate whether, in humans, myocardial thallium-201 uptake can be augmented by pretreatment with a single bolus of sodium bicarbonate at a pharmacological dose, (b) to verify general safety aspects of the intervention and (c) to evaluate the clinical implications of augmentation of ²⁰¹Tl uptake, if any. Routine exercise myocardial scintigraphy was performed twice in eight adult volunteers (five normal and three abnormal), once without intervention and the second time (within a week) following intravenous administration of sodium bicarbonate (88 mEq in 50 ml) as a slow bolus 1 h prior to the injection of ²⁰¹Tl. Conventional myocardial thallium study was compared with sodium bicarbonate interventional myocardial scintigraphy with respect to myocardial uptake (counts per minute per mCi injected dose), washout patterns in normal and abnormal myocardial segments, and overall clinical interpretation based on planar and single-photon emission tomographic (SPET) images. All patients remained asymptomatic after the intervention. A mean increase of 53% in myocardial uptake of thallium was noted in post-exercise acquisitions after the intervention, confirming uptake of the tracer via the potassium-hydrogen pump and its augmentation by transient alkalosis. The washout pattern remained unchanged. The visual quality of planar and SPET images improved significantly after the intervention. Out of the five abnormal myocardial segments identified in three cases, four showed significant filling-in after the intervention, causing the diagnosis to be upgraded from partial scar to ischaemia, or from ischaemia to normal. The overall scan impression changed in two out of three such cases. Sodium bicarbonate augmentation may have significant implications for stress-thallium scintigraphy and may be a new parameter for defining myocardial viability.     

201Tl in the scintigraphic evaluation of the “cold” thyroid areas

²⁰¹Tl-chloride, which has a metabolic behaviour similar to that of potassium and cesium, has been used in 68 patients for the evaluation of thyroid nodules previously recognized as cold on ¹³¹I or ^99mTc scans.All patients were re-examined with gamma-camcra and/or sequential scintigraphic recordings during 60 min after i.v. administration of thallium. In some cases, simultaneous imaging and integral digital plot with ¹³¹I or ^99mTc and ²⁰¹Tl were performed.In all 12 malignant nodules, ²⁰¹Tl has showed a high uptake, while it did not concentrate in 47 benign nodules (cystic or macrofollicular adenomas); thallium uptake was nevertheless found in 10 solid neoformations in which histological pictures were negative for malignancy or atypical lesions.The computerized study of the ²⁰¹Tl intranodular concentration, with the analysis of its dynamic function curves, seems to offer further possibility in differentiating and in a more objective evaluation of the cold areas on the thyroid scan.     

Single-photon emission tomography studies of rubidium-81 in the detection of ischaemic heart disease,using a stress-reinjection protocol

The present study was designed to determine the feasibility of using single-photon emission tomography (SPET) imaging with rubidium-81 (T _1/2 = 4.54 h) to detect ischaernic heart disease, using a stress-reinjection protocol and a specially constructed 511-keV hexagonal hole collimator for a standard gamma camera. The diagnostic performance of ⁸¹Rb SPET in detecting coronary artery disease (CAD) was investigated in 52 patients with a high prevalence of CAD. Coronary arteriography was performed in 34 patients, 25 of whom were classified as having significant stenosis (50%). At peak exercise (Cornell protocol), 111–222 MBq ⁸¹Rb was injected i.v. for stress imaging, and after 3 h of rest, 74–111 MBq was reinjected for rest imaging. The displayed short- and long-axis slices and the polar map images were interpreted qualitatively. In comparison to coronary arteriography, which served as the gold standard, the performance of ⁸¹Rb SPET revealed a sensitivity of 95% for the detection of CAD. Images of diagnostic quality were obtained in all patients, these being comparable to thallium-201 SPET images. In conclusion, these results indicate that the described method can be routinely used for the positron emitter ⁸¹Rb with a conventional gamma camera and special shielding. ⁸¹Rb has the well-known advantages of a potassium analogue and ⁸¹Rb SPET permits better visualization, particularly of the posterior wall of the myocardium, due to the higher photon energy. Considering the typical dose of ²⁰¹Tl used for SPET (74–148 MBq), a ⁸¹Rb SPET scan imposes a significantly lower radiation burden on the patient.     

Headache after lumbar iohexol myelography: the influence of a history of headaches and early ambulation

Whether a history of headache or early versus late ambulation (no bed rest or bed rest for 24 h) influence the occurrence of headache after lumbar iohexol myelography was studied by blinded interviews in 158 consecutive patients referred for elective lumbar myelography (LM) because of suspected lumbar disc prolapse or spinal stenosis. Headache after LM occurred more often in patients with a history of headache (57%) than in patients without such a history (29%),P<0.001. Patients with normal myelographic findings complained of headache after LM more often (55%) than patients with abnormal normal myelographams (31%),P<0.008. No difference in the incidence of headache after LM was demonstrated in early versus late ambulation.Died 27 July 1991     

Detection of coronary artery disease by dynamic planar and single photon emission tomographic imaging with technetium-99m teboroxime

To test the clinical significance of technetium-99m teboroxime regional myocardial clearance in the detection of coronary artery disease, 25 patients underwent dynamic planar or single-photon emission tomographic (SPET) myocardial imaging with ^99mTc-teboroxime after exercise and again 2 h later at rest. All patients underwent both thallium-201 exercise and redistribution SPET and coronary arteriography. The early phases of exercise ^99mTc-teboroxime myocardial clearance determined by dynamic planar imaging showed a significant difference between normal and post-stenotic myocardial regions (clearance rate constant k: 0.047±0.005 min' versus 0.034±0.003 min^–1, P <0.001). Reflecting this differential clearance between myocardial regions, an early redistribution-like phenomenon was observed in a significant number of myocaridal segments by comparing serially acquired post-exercise ^99mTc-teboroxime SPET images. These results indicated that the analysis of ^99mTc-teboroxime myocardial clearance was of potential use in the detection of coronary artery disease, yielding additional information to that provided by the tracer distribution analysis. Although the early redistribution-like phenomenon of ^99mTc-teboroxime could be the source of underestimation of ischaemia if acquisition of the initial post-exercise image were delayed, it could also prove useful in the early differentiation of ischaemia from scar because when the phenomenon was observed in delayed post-exercise images, the rest study could be omitted under some circumstances.     

Local Administration of NF-κ B Decoy Oligonucleotides to Prevent Restenosis after Balloon Angioplasty: An Experimental Study in New Zealand White Rabbits

Purpose To evaluate the efficacy of NF- B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.Materials and Methods In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF- B in two different concentrations (1 g: n=14; 10 g: n=8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.Results NF- B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF- B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm² using 1 g NF- B ODN compared to 0.98 mm² in the control group. The higher dose resulted in a neointimal area of 0.97 mm² compared to 1.07mm² at the control side.Conclusions Local drug delivery of NF- B ODN using the channeled balloon catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.     

Reverse redistribution: fact or fiction?

It has been well documented that it is not uncommon for a thallium-201 perfusion defect to develop or become more evident on delayed exercise thallium scintigraphic imaging, as compared with the initial image immediately following stress. The pathophysiology and clinical significance of the phenomenon are currently unclear. Literature on this subject is reviewed, and it is concluded that reverse redistribution of ²⁰¹Tl in the post-myocardial infarction patient is indeed a fact. In this context it represents a low-risk condition and may imply successful thrombolysis, patent infarct-related coronary artery, improved wall motion at the infarct site and retained myocardial viability in that segment. Correspondence to: A. Labiri     

The influence of orthoses on the proprioception of the ankle joint

The ankle joints of 14 healthy volunteers and 16 patients with unstable ankle joints were tested regarding their functional and proprioceptive capabilities. All of them were active athletes. Three tests were used of the study: single-leg stance test, single-leg jumping course test, angle-reproduction test. The influence of three stabilization devices (lace-on-brace/Mikros, stirrup-brace/ Aircast, taping) on the proprioceptivity of stable and unstable ankle joints was evaluated. The scores of the singleleg jumping course without any stabilizing device (category standard) ranged between 8.06 and 13.68 (10.65±1.29). In the categories Mikros (9.85±0.99), and Aircast (9.99±1.14) as well as with the tape bandage (10.27±0.81) better scores were achieved. The differences standard vs. Mikros and standard vs. Aircast revealed a significant reduction of the scores with orthoses (P<0.01). The error rate in the single-leg stance test was within the range of 0–16 (5.12±2.85) for the category standard. It was lower for the categories Mikros (3.65±2.65) and Aircast (4.17±2.59). The error rate was highest in the group with a tape bandage (5.79±3.53). The differences standard vs Mikros as well as standard vs. Aircast were significant (P<0.01). There was also a significant difference between these categories regarding injured and not injured ankle joints (P<0.01). The angle-reproduction-test showed higher values for the category standard (2.36°±0.97) in comparison to the categories Mikros (1.46°±0.72), Aircast (1.62°±0.91) and taping (1.84°±0.41). In the category standard the reproduction error was lower testing not injured ankle joints (2.30°±1.04) than testing the group of unstable ankle joints (2.44°±0.81), whereas in all other categories the reproduction error was higher in the group of not injured joints. The differences in all measurements between standard vs. Mikros and standard vs. Aircast were significant (P<0.01). The results of the three tests showed a highly significant difference between injured and not injured ankle joints (P<0.01).     

Myocardial viability assessment in patients with highly impaired left ventricular function: comparison of delayed enhancement, dobutamine stress MRI, end-diastolic wall thickness, and TI201-SPECT with functional recovery after revascularization

This study compared different magnetic resonance imaging (MRI) methods with Tl²⁰¹ single photon emission computerized tomography (SPECT) and the gold standard for viability assessment, functional recovery after coronary artery bypass grafting (CABG). Twenty patients (64±7.3 years) with severely impaired left ventricular function (ejection fraction [EF] 28.6±8.7%) underwent MRI and SPECT before and 6 months after CABG. Wall-motion abnormalities were assessed by stress cine MRI using low-dose dobutamine. A segment with a nonreversible defect in Tl²⁰¹-SPECT and a delayed enhancement (DE) in an area >50% of the entire segment, as well as an end-diastolic wall thickness <6 mm, was defined as nonviable. The mean postoperative EF (n=20) improved slightly from 28.6±8.7% to 32.2±12.4% (not significant). Using the Tl²⁰¹-SPECT as the reference method, end-diastolic wall thickness, MRI-DE, and stress MRI showed high sensitivity of 94%, 93%, and 84%, respectively, but low specificities. Using the recovery of contractile function 6 months after CABG as the gold standard, MRI-DE showed an even higher sensitivity of 99%, end-diastolic wall thickness 96%, stress MRI 88%, and Tl²⁰¹-SPECT 86%. MRI-DE showed advantages compared with the widely used Tl²⁰¹-SPECT and all other MRI methods for predicting myocardial recovery after CABG.     

A comparison of dobutamine and maximal exercise as stress for thallium scintigraphy

In the assessment and evaluation of patients with suspected coronary artery disease there is a need for pharmacological stress combined with thallium scintigraphy. Thallium images were obtained following stress both with dobutamine infusion (5–20 g kg^–1 min^–1) and with symptom-limited bicycle ergometry in 20 patients (age 39–70 years) with chest pain who had been admitted for coronary angiography. Percentage thallium uptake was calculated using a region of interest technique. Detailed comparison was performed of the presence, size and distribution of left ventricular thallium perfusion defects; the percentage thallium uptake in ventricles, lung and liver; and the haemodynamic response to stress. Each stress produced a similar number of abnormal segments in each of three views (total EX 166/300; DOB 167/295), but exercise produced larger defects in the anterior view (P<0.025). Thallium uptake in left and right ventricles and relative uptake to lungs were similar, but dobutamine produced higher relative liver uptake [EX 1.55 (0.67); DOB 2.97 (1.23) P<0.0001]. Fourteen patients were able to tolerate dobutamine 20 g kg^–1 min^–1. The ratio of peak stress to rest double product was smaller with dobutamine in both patients with (DOB 1.3; EX 2.0; P<0.0047) and patients without -blockade (DOB 1.5; EX 2.4; P<0.008). Dobutamine produced fewer conventional stress endpoints of chest pain and ST depression. In conclusion, dobutamine produces a well-tolerated incremental pharmacological stress with thallium images similar to maximal exercise, and provides a useful alternative stress in patients unable to perform adequate dynamic exercise.Correspondence to: D.R. Wallbridge     

The stereoisomers of 17α-[123I]iodovinyloestradiol and its 11α-methoxy derivative evaluated for their oestrogen receptor binding in human MCF-7 cells and rat uterus,and their distribution in immature rats

We studied the potential of both stereoisomers of 17-[¹²³I]iodovinyloestradiol (E- andZ-[¹²³I]IVE) and of 11-methoxy-17-[¹²³I]iodovinyloestradiol (E-andZ-[¹²³I]MIVE) as suitable radioligands for the imaging of oestrogen receptor(ER)-positive human breast tumours. The 17-[¹²³I]iodovinyloestradiols were prepared stereospecifically by oxidative radio-iododestannylation of the corresponding 17-tri-n-butylstannylvi-nyloestradiol precursors. Competitive binding studies were performed in order to determine the relative binding affinity (RBA) of the unlabelled 17-iodovinyloes-tradiols for the ER in both human MCF-7 breast tumour cells and rat uterine tissue, compared with that of diethylstilboestrol (DES). Target tissue uptake, retention and uptake selectivity of their¹²³I-labelled analogues were studied in immature female rats. All four 17-iodovi-nyloestradiols showed high affinity for the ER in human MCF-7 cells, as well as rat uterus. Their RBA for the ER showed the following order of decreasing potency: RBA of DES >Z-IVE >Z-MIVE >E-MIVE E-IVE. Neither of these 17-iodovinyloestradiols showed any significant binding to the sex hormone binding globulin in human plasma. The biodistribution studies showed ER-mediated uptake in the uterus, ovaries and pituitary, that ofE- andZ-[¹²³I]MIVE being higher than that ofE- andZ-[¹²³I]IVE. High target-to-non-target tissue uptake ratios, especially at longer periods after injection (up to 24 h), were exhibited by both isomers of [¹²³I]MIVE. The uterus-to-blood uptake ratio was higher for^E-[¹²³I]MIVE. However, the uterus-to-fat uptake ratio appeared to be higher for theZ-isomer of [¹²³I]MIVE, especially at 24 h after injection. Metabolic properties and temperature effects, which play a more important role in vivo, probably cause the discrepancies seen between in vitro and in vivo binding results. On the basis of their in vitro binding properties and in vivo distribution characteristics we conclude thatE- andZ-[¹²³I]MIVE could be suitable radioligands for the diagnostic imaging of ER in human breast cancer. Therefore, further studies with these radioligands in mature normal and tumour-bearing rats are warranted.