Anne Sophie Hambye

Prediction of functional outcome by quantification of sestamibi and BMIPP after acute myocardial infarction

Abstract. Iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) can be used to image myocardial fatty acid regional distribution and utilisation with single-photon emission tomography (SPET). By visual analysis, a mismatching with regional uptake of BMIPP less than that of a perfusion tracer has been shown to predict myocardial viability and functional improvement after restoration of flow in patients with myocardial infarction. The current study aimed to evaluate a newly developed quantitative method of analysis of sestamibi and BMIPP uptake for the prediction of functional recovery after revascularization in patients with acute infarction. BMIPP and gated sestamibi SPET studies at rest were obtained before and >3 months after revascularization in 18 patients with recent infarction. A colour-coded polar map was generated from the comparison of sestamibi and BMIPP uptake. Depending on the relative distribution of the two tracers, different patterns of uptake were identified and their extent expressed as percentages of the surface of the whole left ventricle and of the three main coronary artery territories. At follow-up, recovery was defined as a ≥5% increase in ejection fraction compared with baseline. Receiver-operating characteristic curve analysis was performed to analyse the data. At baseline, significant correlations were found between ejection fraction and the % surface with decreased sestamibi or BMIPP uptake (r=–0.68, P= 0.001, and r=–0.72, P<0.0001, respectively). When combining both tracers, ejection fraction was significantly associated with the extent of myocardium showing decreased sestamibi uptake with lower BMIPP uptake (mismatching; r=–0.68, P=0.001). At follow-up, significant functional recovery was found in 13/18 patients. By ROC curve analysis, the optimal pattern of distribution predicting recovery was a mismatching with uptake of sestamibi <70% and uptake of BMIPP at least 10% lower. For this parameter, optimal cut-off of extent was 10% of the whole left ventricle surface (sensitivity 69%, specificity 80%, accuracy 72%) and 25% of the infarct-related arterial territory (sensitivity 77%, specificity 80%, accuracy 78%). The areas under the curve were 79% for the left ventricle surface and 72% for the individual arterial territories. These results suggest that in patients with acute infarction, quantitative analysis of sestamibi and BMIPP could offer an objective and reproducible method for estimating the severity of cardiac dysfunction and predicting the evolution of ejection fraction after revascularization.

Influence of the different biokinetics of sestamibi and tetrofosmin on the interpretation of myocardial perfusion imaging in daily practice.

AimDigestive activity can interfere with the interpretation of myocardial perfusion single photon emission computed tomography using sestamibi or tetrofosmin. Compared with sestamibi, the liver clearance of tetrofosmin is more rapid, but its absolute cardiac uptake is lower. In this study, the activity of sestamibi and tetrofosmin was quantified after exercise or pharmacological stress and at rest to objectify the biokinetic differences and to evaluate whether there is a correlation between quantitative measurements and the visual assessment of image quality. MethodsLeft ventricular activity and five ratios (R1–R5) of cardiac to adjacent extra-cardiac activity were quantified in 204 sestamibi (68 exercise stress/56 pharmacological stress/80 rest) and 221 tetrofosmin (67 exercise stress/59 pharmacological stress/95 rest) studies. Image quality was assessed by a three-point score (1, good; 2, moderate; 3, poor) and correlated with the heart to left supra-diaphragmatic region (R1) and heart to right supra-diaphragmatic region (R2) ratios. ResultsThe mean left ventricular activity was higher for sestamibi, especially at rest (sestamibi, 0.21±0.05 counts/pixel/injected MBq; tetrofosmin, 0.16±0.042 counts/pixel/injected MBq; P<0.001). By contrast, most ratios were higher with tetrofosmin, particularly for the exercise stress and rest studies. Using the three-point quality scoring, more sestamibi than tetrofosmin studies were scored as 3 (12.2% versus 6.3%), also particularly for the exercise stress and rest studies. A highly significant relationship was found between decreasing R1 and R2 and an increasing quality score, regardless of the radiopharmaceutical used (P values between 0.02 and <0.001). ConclusionsDespite a lower cardiac uptake, the more rapid liver clearance of tetrofosmin than sestamibi significantly improves the ratios of cardiac to digestive activity, especially after exercise or at rest. These quantitative differences in biokinetics result in less poor scans with tetrofosmin in daily practice.

FP-CIT SPECT in clinically inconclusive Parkinsonian syndrome during amiodarone treatment: a study with follow-up.

ObjectivesTo evaluate whether dopamine transport system imaging by FP-CIT single-photon emission computed tomography (SPECT) can be helpful to differentiate idiopathic Parkinsons disease (IPD) from secondary Parkinsonism induced by amiodarone. MethodsTwenty-two patients with Parkinsonism during amiodarone therapy were evaluated by clinical neurological examination and FP-CIT SPECT. Thereafter, amiodarone was discontinued whenever possible and antiparkinsonian treatment was modified, if required. Clinical neurological status was reevaluated within a year of the SPECT examination. ResultsAt baseline, clinical neurological examination was quite similar in all patients. No clinical symptom was able to clearly orientate the diagnosis toward IPD or drug-induced Parkinsonism. Using SPECT, the number of normal and abnormal patients was evenly distributed. In the abnormal SPECT group, amiodarone was modified in seven patients of whom six improved at follow-up. Antiparkinsonian treatment had been modified in all the patients. In the four cases with no amiodarone changes, clinical improvement was noted if antiparkinsonian treatment was optimized (three patients). In the 11 normal SPECT patients, amiodarone was modified in five patients. All patients ameliorated (two) or even normalized (three). In the six patients with normal SPECT in whom amiodarone had not been modified, symptoms remained stable despite the absence of antiparkinsonian treatment. ConclusionIn patients treated with amiodarone, IPD is sometimes clinically difficult to differentiate from drug-induced Parkinsonism. Using FP-CIT, a normal scan suggests drug-induced Parkinsonism, hence, there is no need for antiparkinsonian treatment and all possible attempts to reduce or preferably stop amiodarone. An abnormal scan, on the other hand, indicates IPD. In this case, treating IPD seems to have more impact on motor changes than modifying the antiarrhythmic drug.

Chronic brain hypoperfusion due to multi-vessel extracranial atherosclerotic disease: a potentially reversible cause of cognitive impairment.

A 62-year-old patient presented with persistent cognitive deficits 3 months after a right temporal ischemic stroke due to ipsilateral carotid occlusion. Work-up disclosed hemodynamically significant contralateral carotid artery stenosis and left subclavian steal phenomenon. Brain SPECT imaging revealed bihemispheric chronic brain hypoperfusion that substantially improved on repeat imaging when the subclavian steal was temporarily diminished by inflating a cuff around the left arm. Carotid endarterectomy of the asymptomatic carotid stenosis substantially ameliorated bihemispheric brain perfusion and reversed cognitive impairment. This case highlights that multi-vessel, extracranial atherosclerotic disease may cause chronic diffuse brain hypoperfusion that can be associated with cognitive impairment.

BMIPP imaging to assess functional outcome in patients with acute and chronic left ventricular dysfunction.

Assessment of myocardial viability is an important clinical issue for patient management during the acute and chronic stages of myocardial infarction. BMIPP (15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid) is a free fatty acid analogue which is trapped in the myocardium, thus permitting for metabolic imaging with single photon emission computerized tomography (SPECT). Less BMIPP than flow tracers that may be observed in the areas of infarction, may reflect the metabolic shift from fatty acid to glucose utilization in ischaemic myocardium. In this sense, the combined imaging of BMIPP and a flow tracer with SPECT may provide similar and important information as fluoro-18 deoxyglucose (FDG) and positron emission tomography (PET) regarding the assessment of myocardial viability. The purpose of this article is to review the clinical impact of BMIPP in patients with acute and with chronic left ventricular dysfunction for the identification of jeopardized but viable myocardium and the prediction of the functional outcome.

SPET-generated colour-coded polar maps to quantify 99Tcm-MIBI and 123I-BMIPP uptake in chronically dysfunctional myocardium: Comparison with coronary anatomy and wall motion

The combined use of 123I-BMIPP and 99Tcm-MIBI SPET imaging has been proposed as an alternative to PET for the non-invasive detection of jeopardized myocardium after a myocardial infarction, a mismatch accurately indicating jeopardized but still viable tissue. In this paper, a new quantitative approach is described, expressing the presence and degree of mismatch as the percentage of the left ventricular surface globally as well as for each major epicardial artery by means of clearly identified colour-coded polar maps. With this method, the relative proportion of normal and scar tissue, each characterized by a specific colour, is measured using thresholds of 99Tcm-MIBI uptake of 60% and 30% of the expected mean normal value respectively, whereas the presence and extent of mismatch between 99Tcm-BMIPP and 99Tcm-MIBI are calculated only between these two thresholds, typically corresponding to a reduction in flow associated with a possible but uncertain post-revascularizarion recovery. Applied to 15 patients with severely impaired left ventricular function after a myocardial infarction, small intra- and inter-observer differences were noted in the assessment of the relative proportion of normal, mismatched and scar tissue. More specifically, analysing the variability in the calculated percent mismatch, good reproducibility was observed, with intra- and interobserver correlation coefficients of 0.96 and 0.94 respectively, a mean (

Educational impact of discussing results among nuclear medicine physicians participating in interobserver reproducibility studies: Our experience with I-123 FP-CIT SPECT

PT S.D.) intra-observer difference of 0.25

Head-to-head comparison of uncorrected and scatter corrected, summed and end diastolic myocardial perfusion SPECT in coronary artery disease.

PT2.0% for the left ventricle globally, 1.65

Secondary hypertrophic osteoarthropathy on bone scintigraphy as a diagnosis of vascular prosthesis infection.

PT 2.9% for the left anterior descending artery (LAD), −1.56

Influence of high-energy photons on the spectrum of iodine-123 with low- and medium-energy collimators: Consequences for imaging with 123I-labelled compounds in clinical practice

PT 3.6% for the left circumflex artery (LCX) and −1.24