Tc-99m Pyrophosphate Research Articles

Cardiac amyloidosis in patients undergoing aortic valve replacement for aortic stenosis

Abstract Background Transthyretin cardiac amyloidosis (ATTR) has been increasingly recognized in patients with degenerative aortic stenosis (AS). In some reports, the uptake of Tc-99m labeled bone radiotracers in cardiac amyloidosis has been documented. Tc-99m pyrophosphate (PYP) scintigraphy in the absence of evidence of a monoclonal gammopathy was diagnostic for transthyretin cardiac amyloidosis, providing a cost-effective and non-invasive technique with a specificity and positive predictive value of nearly 100%. We sought to determine the prevalence of ATTR as detected by the bone scan tracer among the patients with severe AS requiring surgical valve replacement. Methods We retrospectively analyzed clinical and echocardiographical data for 44 patients with severe AS requiring surgical valve replacement between Jan. 2009 and Dec. 2016. All eligible patients were offered Tc-99m PYP scintigraphy. Retention of Tc-99m PYP in the heart was assessed using both a semiquantitative visual score (range, 0 [no uptake] to 3 [uptake greater than bone]). Positive uptake was defined score 2 and 3. Results Myocardial deposition of Tc-99m PYP (Score 2–3) was identified in 4 of 44 patients (9%), all >70 years and 75% male. Patients with myocardial deposition of the tracer were older (78±8 years vs. 70±12 years), and had more mean interventricular septum thickness (18±3 mm vs. 14±5 mm). Both groups had at least ejection fraction and abnormal global longitudinal strain with no significant difference between groups. Pre-operative serum median NT-pro BNP level was similar between two groups, but post-operative improvement of NT-pro BNP was larger in non-deposition of the tracer group. During the post operative follow-up, survival was significantly worse if patients had amyloid deposition compared with no deposition subjects (25% vs. 7.5%). Conclusion Incidental transthyretin cardiac amyroidosis had a prevelance of 9% among patients undergoing surgical aortic valve replacement and was associated with a poor outcome. Funding Acknowledgement Type of funding source: None

Evaluation of ATTR-cardiac amyloidosis employing Tc-99m pyrophosphate scintigraphy using planar, SPECT and gated SPECT imaging on dedicated cardiac CZT camera

Abstract Background/Introduction Recent recognition that ATTR cardiac amyloidosis (ATTR-CA) is not uncommon and the emergence of novel therapeutic opportunities resulted in the publication of “Expert Consensus Recommendations for Multimodality Imaging in Cardiac Amyloidosis”. However, almost all data were derived from general purpose NaI cameras, while new cardiac dedicated CZT cameras are becoming more widespread. Purpose To evaluate Tc-99m pyrophosphate (PYP) scintigraphy on D-SPECT cardio dedicated CZT camera (Spectrum Dynamics) in suspected ATTR-CA patients. Methods Seventy three consecutive patients suspected for ATTR-CA underwent planar (5 min), SPECT and gated SPECT (10 min, 8 bins) scintigraphy 89±26 min after injection of Tc99m-PYP 740 MBq, followed by late scintigraphy after 92±36 min in 65 consecutive patients. Perguini visual score, planar H/CL and SPECT derived H/CL ratio were evaluated by two blinded independent experienced readers. Diagnosis was based on visual interpretation after blood pool and monoclonal gammopathy were excluded. Results Very good to excellent planar and SPECT image quality was observed in almost all patients. PYP scintigraphy was positive in 6/73 patients, with left ventricular wall uptake clearly evident in the planar images of most patients. There was perfect agreement between readers regarding positive/negative interpretation. There was also substantial inter-observer agreement regarding the Perguini scoring (Cohen's k with linear weighting 0.819, 95% CI 0.701–0.937). Inter-observer agreement for H/CL ratio was also good (Pearson's correlation coefficient r(71)=0.873). SPECT and gated SPECT images were helpful only in one positive patient, and did not have an added value in any of the negative studies. Slightly better images were observed during late scintigraphy, but there was no change in interpretation, and H/CL ratio was not significantly changed (median difference −0.01, IQR 0.09). Alas, Inter-observer agreement of H/CL ratio was lower (Pearson's correlation coefficient r(64)=0.633). We also evaluated H/CL ratio derived from SPECT based application of the camera manufacturer. Agreement between early planar and early SPECT based H/CL ratio was good for both readers (r(69)=0.778 and r(66)=0.747), but inter-observer agreement was lower (r(66)=0.697). Conclusions ATTR PYP scintigraphy using cardiac dedicated CZT camera yielded excellent images in almost all patients, and uptake in the left ventricular wall could be easily identified in positive patients. Inter-observer agreement was excellent for both visual scoring and planar H/CL ratio. Early planar images were high quality, and limited additional diagnostic value was observed for both SPECT and gated SPECT scintigraphy and from later acquisition. Funding Acknowledgement Type of funding source: None

Positive Tc-99m Pyrophosphate Scintigraphy Predicts Thromboembolic Risk in Patients with Congestive Heart Failure and Atrial Fibrillation

Background Tc-99m pyrophosphate scintigraphy (PYP) has unmasked a high community prevalence of wild-type transthyretin cardiac amyloidosis (ATTRwt-CA), which is an increasingly recognized etiology of congestive heart failure (CHF) in the elderly. CHF is a known component of the CHA2DS2-VASc score that predicts thromboembolic risk in atrial fibrillation (AF). However, the impact of ATTRwt-CA on thromboembolic risk in AF is unknown. Hypothesis We hypothesized that ATTRwt-CA independently predicts thromboembolism in CHF patients with atrial fibrillation. Methods We studied patients with underlying CHF who underwent PYP between 6/2015 and 6/2019. Positive PYP was defined as Perugini grade ≥2 along with heart-to-contralateral lung ratio of ≥ 1.5 on planar image, and diffuse myocardial tracer uptake on the SPECT. Those with positive PYP, negative serum studies for AL amyloidosis and no transthyretin gene mutation were diagnosed with ATTRwt-CA. We compared the prevalence of AF in patients with and without ATTRwt-CA and the incidence of thromboembolism (stroke, transient ischemic attack or systemic embolism) in AF patients with ATTRwt-CA (AF-ATTR) and without (AF-controls). Results Of 277 patients referred for PYP, 77 (28%) had ATTRwt-CA. The prevalence of AF was markedly higher in patients with ATTRwt-CA (n=68, 88%) compared to patients with negative PYP (n=77, 39%, p Conclusion ATTRwt-CA is a strong predictor of thromboembolism in patients with AF, independent of CHA2DS2-VASc score, septal thickness or left atrial size.

Amyloidosis Prediction Score: A Clinical Model for Diagnosing Transthyretin Cardiac Amyloidosis

Introduction Tc-99m Pyrophosphate (PYP) scintigraphy has a high diagnostic accuracy for transthyretin cardiac amyloidosis (ATTR-CA). Referral for PYP imaging is guided by certain clinical features which are variably present among patients with ATTR-CA. We aimed to derive a clinical score that would allow for prediction of a positive PYP study. Hypothesis We hypothesized that a clinical score, derived from multiple predictive variables, could be used to predict positive PYP. Methods Demographic, clinical, ECG and echocardiographic data for all patients who underwent PYP imaging between 06/2015 to 01/2020 were recorded. Variables that independently predicted a positive PYP study were identified from multivariable logistic regression analysis, and were assigned a numerical value (e.g. -1 for age 80 years). These values were then weighted by the prevalence of these predictors in the study cohort. Amyloidosis Prediction Score (APS) was derived, for each patient, as the sum of the weighted scores of the independent predictors. Receiver operating curve analysis was used to determine the accuracy of APS for predicting a positive PYP study. Results Data of 440 patients (mean age at PYP 75 ± 11, 71% men, 81% Caucasians) was analyzed, of which 126 (28.6%) had a positive PYP study. Age, male gender, bilateral carpal tunnel syndrome, lumbar spinal stenosis, atrial fibrillation, low QRS voltage, pseudo-infarct pattern and left ventricular hypertrophy were significant independent predictors of a positive PYP study (table). APS values ranged from -10 to +13, and predicted a positive PYP study with an accuracy of 0.98 (figure). An APS value of 3.2 conferred a sensitivity and specificity of 96% and 91% for predicting a positive PYP study, respectively, with a positive likelihood ratio of 10. Conclusion The Amyloidosis Prediction Score has a high diagnostic accuracy for a positive PYP study and can be easily determined from clinical history and routinely assessed ECG and echocardiographic features. This score has the ability to increase the diagnostic yield of PYP scintigraphy.

The role of β-adrenergic receptors in stress-induced cardiac injury in a rat model of Takotsubo syndrome

Introduction. The pathophysiological mechanisms of cardiac injury in Takotsubo syndrome are currently poorly understood. The role of adrenergic receptor (AR) subtypes in the development of stress-induced myocardial injury (SIMI) remains unclear.Aim. To assess the role of β-ARs in the development of SIMI.Material and Methods. The study was performed using female Wistar rats (n = 84). Rats were subject to 24-hour immobilization in the supine position to simulate SIMI. 99mTc-pyrophosphate radiopharmaceutical was used to determine the degree of cardiac injury.Results. The study showed that β-AR blockade with propranolol reduced the degree of cardiac injury by 38.4%. Selective β1- AR antagonists, atenolol and nebivolol, led to 2.00- and 2.55-fold decreases in 99mTc pyrophosphate accumulation in the heart, respectively. Blockade of β2-ARs by a selective antagonist ICI-118.551 caused an increase in the degree of 99mTc-pyrophosphate accumulation in the heart by 34.6%. A selective β3-AR antagonist L-748337 did not affect 99mTc pyrophosphate accumulation in the heart.Conclusions. The study showed that β1-ARs are involved in the damaging effects of stress on the heart during immobilization stress. β2-AR had a cardioprotective effect in immobilization. β3-AP did not play a significant role in the stress-induced cardiac injury with a single exposure to the stressor.

WILD-TYPE TRANSTHYRETIN AMYLOID CARDIOMYOPATHY PREDICTS THROMBOEMBOLIC RISK IN ATRIAL FIBRILLATION

The impact of wild-type transthyretin amyloid cardiomyopathy (ATTR-CA wt) on thromboembolic risk in patients with atrial fibrillation (AF) is unknown. We studied patients who underwent Tc-99m pyrophosphate scintigraphy (PYP) between 6/2015 and 6/2019. Those with positive PYP, negative serum for AL

FASTER PROGRESSION OF LEFT VENTRICULAR THICKNESS IN MEN COMPARED TO WOMEN IN WILD-TYPE TRANSTHYRETIN CARDIAC AMYLOIDOSIS

We determined the progression of LV thickness and its association with ECG, biomarkers and symptoms in untreated wild-type transthyretin cardiac amyloidosis (ATTR-CA wt). Measurements were made on 2 echocardiograms, at least 18 months apart, before and after the diagnostic Tc-99m pyrophosphate (PYP

Estimating cancer risk from 99mTc pyrophosphate imaging for transthyretin cardiac amyloidosis

BackgroundIncreasing recognition that transthyretin cardiac amyloidosis (ATTR-CA) is much more common than previously appreciated and the emergence of novel disease-modifying therapeutic agents have led to a paradigm shift in which ATTR-CA screening is considered in high-risk populations, such as patients with heart failure with preserved ejection fraction (HFpEF) or aortic stenosis. Radiation risk from 99mTc-pyrophosphate (99mTc-PYP) scintigraphy, a test with very high sensitivity and specificity for ATTR-CA, has not been previously determined. Methods and ResultsRadiation doses to individual organs from 99mTc-PYP were estimated using models developed by the Medical Internal Radiation Dose Committee and the International Commission on Radiological Protection. Excess future cancer risks were estimated from organ doses, using risk projection models developed by the National Academies and extended by the National Cancer Institute. Excess future risks were estimated for men and women aged 40-80 and compared to total (excess plus baseline) future risks. All-organ excess cancer risks (90% uncertainty intervals) ranged from 5.88 (2.45,11.4) to 12.2 (4.11,26.0) cases per 100,000 patients undergoing 99mTc-PYP testing, were similar for men and women, and decreased with increasing age at testing. Cancer risks were highest to the urinary bladder, and bladder risk varied nearly twofold depending on which model was used. Excess 99mTc-PYP-related cancers constituted < 1% of total future cancers to the critical organs. ConclusionVery low cancer risks associated with 99mTc-PYP testing suggest a favorable benefit-risk profile for 99mTc-PYP as a screening test for ATTR-CA in high-risk populations, such as such as patients with HFpEF or aortic stenosis.

Efficient 1-Hour Technetium-99 m Pyrophosphate Imaging Protocol for the Diagnosis of Transthyretin Cardiac Amyloidosis.

Technetium-99 m pyrophosphate protocols for transthyretin cardiac amyloidosis diagnosis have variably used 1- and 3-hour imaging time points. We investigated whether imaging at 1 hour with superior efficiency had comparable diagnostic accuracy as 3-hour imaging. This is a registry analysis of patients with suspected transthyretin cardiac amyloidosis referred for technetium-99 m pyrophosphate at a single tertiary center from June 2015 through January 2019. Patients underwent planar and single-photon emission computed tomography (SPECT) imaging at 1 and 3 hours. A positive Tc-99m pyrophosphate study was defined by the presence of diffuse myocardial tracer uptake on SPECT. For planar imaging, visual semiquantitative (grades 0-3, ≥2 considered positive) and quantitative heart to contralateral ratios (≥1.5 considered positive) were used. Two hundred thirty-three patients (69% men; median age, 77 [69-83] years) underwent the study protocol. There were 60 (25.8%) patients with diffuse myocardial uptake, 1 (0.4%) with regional uptake, and 172 (73.8%) with no myocardial uptake. Results of SPECT were identical at 1 and 3 hours. Planar imaging at 1 hour had 98% sensitivity and 96% specificity. Planar grade 0 uptake or heart to contralateral ratio ≤1.2 and planar grade 3 uptake or heart to contralateral ratio ≥2.0 were always associated with negative and positive SPECT, respectively. For planar grades 1 and 2 uptake and heart to contralateral ratio 1.3 to 1.9, SPECT was needed to make a diagnosis. No patient with light-chain cardiac amyloidosis had positive SPECT. An efficient 1-hour technetium-99 m pyrophosphate protocol had comparable diagnostic performance to a 3-hour protocol.

Varying levels of small microcalcifications and macrophages in ATTR and AL cardiac amyloidosis: implications for utilizing nuclear medicine studies to subtype amyloidosis.

Recently, there has been much interest in using nuclear medicine studies to noninvasively identify and subtype cardiac amyloidosis. In particular, modified bone scans using (99m)Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) and (99m)Tc-pyrophosphate ((99m)Tc-PYP) are being used to selectively identify patients with ATTR amyloidosis rather than AL amyloidosis. The morphologic basis underlying the selectivity of these imaging modalities for ATTR amyloidosis has been unclear. To determine if variations in microcalcifications and/or macrophages within ATTR and AL amyloidosis might be responsible for the selectivity for these imaging modalities, 8 endomyocardial biopsies of ATTR amyloidosis and 7 endomyocardial biopsies of AL amyloidosis were stained with von Kossa calcium stains and with immunohistochemistry for the macrophage marker CD68. Compared with AL amyloidosis, there was a greater density of small microcalcifications in cases of ATTR amyloidosis (mean=16.8 vs. 6.5 per 200× field, P=.008). In contrast, there were fewer macrophages in ATTR amyloidosis compared with AL amyloidosis (mean=2.5 vs. 11.7 per 200× field, P=.0004). The density of microcalcifications within each group was not related to patient age, echocardiographic features of cardiac function, or serum levels of calcium and creatinine. These data suggest that microcalcifications but not macrophages likely underlie the selectivity of modified bone scans for ATTR amyloidosis and suggest that other pathologic entities containing microcalcifications might also result in positive scans with these imaging modalities.

Cardiac amyloidosis detected on tc-99m bone scan.

Cardiac amyloidosis is an important cause of restrictive cardiomyopathy and congestive heart failure. There are two major types of cardiac amyloidosis: cardiac amyloid light-chain (AL) and transthyretin-related cardiac amyloidosis (ATTR) [1, 2]. The treatment options and prognosis for these two subtypes are different. The AL subtype cardiac amyloidosis is associated with greater than 50 % mortality within 6 months after the diagnosis, while the ATTR subtype has a more favorable prognosis of 98–100 % 2-year survival [3, 4]. Therefore, differentiating the type of cardiac amyloidosis (AL vs. ATTR) is crucial in guiding patient care. Due to its variable clinical symptoms, as well as the nonspecific ECG and echocardiographic presentations, cardiac amyloidosis is a diagnostic challenge and usually underdiagnosed [5, 6]. Endomyocardial biopsy remains the gold standard for diagnosis (Fig. 1). Fig. 1 A 68-year-old male with prostate cancer underwent a bone scan for disease staging. Diffuse cardiac uptake of the bone-seeking radiotracer, Tc-99m MDP (methylene diphosphonate), was incidentally found (arrow, a: bone scan). Given the patient’s ... Perugini et al. [7] demonstrated Tc-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (Tc-99m DPD) bone scan findings among patients with cardiac amyloidosis of ATTR (n = 15) and AL (n = 10) subtypes in which cardiac Tc-99m DPD uptake was present in all ATTR patients and absent in all AL patients at visual assessment. Rapezzi et al. [8] evaluated myocardial uptake of Tc-99m DPD in patients with ATTR-related (n = 45, 28 mutant and 17 wild-type) and AL-related (n = 34) cardiac amyloidosis as well as 15 nonaffected controls. On semiquatitative analysis, patients with ATTR had higher visual scoring of cardiac retention (range: score 0, absent cardiac uptake and normal bone uptake; score 1, mild cardiac uptake, inferior to bone uptake; score 2, moderate cardiac uptake accompanied by attenuated bone uptake; score 3, strong cardiac uptake with attenuated bone uptake), with positive and negative predictive values of 88 and 100 % (visual score ≥2). On quantitative analyses, compared to AL and unaffected controls, ATTR patients also had significantly higher (p < 0.0001) heart retention (HR, 7.8 %) and heart-to-whole-body retention ratios (H/WB 10.4), while both unaffected controls (HR 3.5 %; H/WB 5.7) and AL subtypes (HR 4.0 %; H/WB 6.1) were similarly low. Another bone scintigraphic tracer, Tc-99m hydroxymethylene diphosphonate (Tc-99m HDP), has shown high cardiac retention and H/WB ratios in 19 of 30 patients with ATTR cardiac amyloidosis [9]. Bokhari et al. [10] reported that 45 subjects (12 AL, 16 ATTR wild type and 17 ATTR mutants) underwent Tc-99m pyrophosphate (Tc-99m PYP) cardiac imaging. Subjects with ATTR cardiac amyloid had a significantly higher semiquantitative cardiac visual score (range, 0; no uptake to 3, diffuse uptake) than the AL cohort (2.9 ± 0.06 versus 0.8 ± 0.27; P < 0.0001) as well as a higher quantitative score (1.80 ± 0.04 versus 1.21 ± 0.04; P < 0.0001). Using a heart-to-contralateral-lung ratio of 1.5 on Tc-99m PYP cardiac imaging distinguished ATTR amyloidosis (≥1.5) from AL amyloidosis (<1.5), with 97 % sensitivity and 100 % specificity. Sporadic case reports [11, 12] have shown that Tc-99m MDP radiotracers can accumulate in the heart in patients with cardiac amyloidosis; however, there were no corresponding myocardium tissue biopsy results. Our case demonstrated that intense cardiac uptake of Tc-99m MDP correlates with biopsy-proven ATTR cardiac amyloidosis. We think that the preferential binding of Tc-99m MDP to ATTR is similar to those of Tc-99m PYP, Tc-99m DPD (not available in the USA) and Tc-99m HDP, which may be due to the fact that transthyretin amyloid fibrils have higher calcium contents. Given its universal availability, Tc-99m MDP imaging may serve as a noninvasive adjunct in the differential diagnosis of cardiac amyloid.

Ischemic Preconditioning Effect of Prodromal Angina Is Attenuated in Acute Myocardial Infarction Patients With Hypertensive Left Ventricular Hypertrophy

Several animal experiments on acute myocardial infarction (AMI) have shown that the cardioprotective effects of ischemic preconditioning are more significant in hypertensive subjects. However, because there are no clinical data on the impact of hypertension on ischemic preconditioning in patients with AMI, whether clinical ischemic preconditioning of prodromal angina was beneficial in AMI patients with hypertension was investigated in the present study. 125 patients with a first anterior AMI who had undergone successful reperfusion therapy were divided into 2 groups, with or without hypertension, and into 2 further subgroups based on the presence or absence of prodromal angina. Dual-isotope (thallium-201(TL)/Tc-99m pyrophosphate) single-photon emission computed tomography (SPECT) was performed within 1 week of reperfusion therapy. Left ventricular (LV) function and LV mass index (LVMI) were measured by left ventriculography and echocardiography, respectively. In patients without hypertension, prodromal angina resulted in significantly less myocardial damage on TL-SPECT, better LV ejection fraction and a greater myocardial blush grade compared to patients without prodromal angina. However, these cardioprotective effects of prodromal angina were significantly diminished in hypertensive patients. Importantly, the myocardial salvage effects of prodromal angina showed a significant negative correlation with LVMI, which was significantly greater in hypertensive patients. The cardioprotective effects of prodromal angina were attenuated in patients with hypertension. Hypertensive LV hypertrophy may crucially limit the effects of ischemic preconditioning in AMI.

Myocardial Infarction Without Coronary Artery Stenosis Illustrated by Tc-99m Pyrophosphate Scan, Cardiac Magnetic Resonance Imaging, and Myocardial Perfusion Scintigraphy

A 42-year-old woman presented with chest pain and ECG changes suggestive of acute myocardial infarction. However, a coronary angiogram showed no significant epicardial coronary stenosis. Nonetheless, abnormal Tc-99m pyrophosphate activity accumulated within the inferolateral wall, consistent with acute necrosis. Cardiac magnetic resonance revealed near transmural extent of late gadolinium-enhancement with mild hypokinesis in the mid to basal inferolateral segments. Dipyridamole Tl-201 single photon emission computed tomography 6 months later demonstrated stress-induced ischemia in the corresponding area, with subendocardial scar in the mid level. Nuclear perfusion scintigraphy is needed for accurate assessment of infarct size and coronary flow after the acute stage of a myocardial infarction has passed.

A new imaging modality in detection of caustic oesophageal injury: Technetium-99m pyrophosphate scintigraphy

Early oesophagoscopy is usually recommended in children after caustic ingestion to assess the severity of the initial digestive lesions. An oesophagoscopic procedure in children always demands to be performed under sedation and bears a certain risk of iatrogenic injury. The purpose of the study is to determine the value and sensitivity of Tc-99m pyrophosphate (99mTc-PYP) scintigraphy for the detection of caustic oesophageal injury. The caustic oesophageal burns were created with 25% NaOH in an experimental rat model. Seventeen rats were divided into two groups. The BURN group (n=9) included caustic oesophageal burning rats. Non-BURN group (n=8) included sham-operated rats. All animals underwent 99mTc-PYP scintigraphy 72 h after the burning experiment. Anterior static and single-photon emission computed tomography images were obtained using a low-energy all-purpose collimator, 2.55 zoom factor, 3h after intravenous injection of 10 mCi 99mTc-PYP. After the imaging, all the oesophagi were explored for external determination of the injury sites and macroautoradiographic scintigraphy as well. Rectangular region of interest were placed in the visually determined lesion of oesophagus (O) as well as non-lesion area (N), and an ON ratio was created. The severity and extension of oesophageal burn were assessed 3 days after burning by histopathologic evaluation. The injuries were graded according to the ulcer depth, ulcer width, thrombus formation, and the development of perivascular fibrinoid necrosis. The oesophageal burning areas were demonstrated by visual evaluation of the Tc-99m PYP scintigraphy on all animals. The mean ON ratio of 99mTc-PYP was 21.61+/-7.01 in the BURN group and in the non-BURN group, was 2.25+/-0.24 (p<0.001). The best cut-off point of the ON ratio for caustic oesophageal injury was 5.45, with sensitivity and specificity of 100%. PYP scan findings were also confirmed by histological evidence of ulcer depth, ulcer width, thrombus formation, and perivascular fibrinoid necrosis in the same areas. The caustic oesophageal injuries have been demonstrated by 99mTc-PYP scintigraphy in burning experiment. 99mTc-PYP scintigraphy is sensitive for detection of caustic oesophageal injury. This new imaging tool is found to be sensitive and specific for the detection of caustic oesophageal injury in the rats.

Important factors for salvaging myocardium in patients with acute myocardial infarction

This study was designed to evaluate the factors that affect myocardial salvage after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). One hundred and eighty-three patients with AMI who had undergone successful PCI were recruited for this study. Patients underwent (99m)Tc-pyrophosphate single photon emission computed tomography (SPECT) on the third day and (99m)Tc-MIBI SPECT on the sixth day after admission. In the 20 SPECT segments, the summed defect score (TDS) and extent score (ES) of AMI segments were determined and the percentage of the salvaged myocardium was calculated based on the TDS and ES. We performed multivariate analysis to evaluate factors that can affect myocardial salvage. Multivariate analysis was performed among the value of myocardial salvage rate and the 15 clinical variables. Administration of nicorandil (p=0.006), prodromal angina (p<0.001), and high TIMI grade (p<0.001) had significant positive correlation to myocardial salvage rate. Use of a distal protection device had a significant negative correlation with myocardial salvage rate (p=0.006). The presence of high TIMI grade before PCI and prodromal angina are very important for salvaging myocardium. Furthermore, administration of nicorandil is important in salvaging myocardium in patients with AMI.

Dual SPECT Imaging With Tc-99m Pyrophosphate and Tl-201 of Circumferential Subendocardial Myocardial Infarction in Aortic Stenosis Without Coronary Artery Stenosis

An 88-year-old woman with aortic stenosis, who had demonstrated fever for several preceding days, complained of angina and orthopnea. Although the symptoms were suggestive of acute myocardial infarction, coronary angiography failed to demonstrate coronary artery stenosis. Dual SPECT with Tc-99m pyrophosphate and Tl-201 demonstrated an abnormal accumulation of the former tracer throughout the inner layers of the left ventricle, indicating circumfer- ential subendocardial infarction. Confirmation of this diagnosis is often difficult, and there have been only a few documented cases. However, the present images clearly depicted this unusual view of infarction in a patient with aortic stenosis but without coronary artery stenosis.

Sympathetic Dystrophy Associated With Sirolimus Therapy

The reflex sympathetic dystrophy syndrome (RSDS) in organ transplant recipients has only previously been reported in patients treated with calcineurin inhibitors. We retrospectively analyzed 393 renal transplant patients treated with sirolimus, 9 of whom developed RSDS. All the patients reported varying degrees of pain in the legs, affecting the knees, ankles, and/or feet, plus cutaneous erythema. The onset of pain ranged from 1-6 months after transplantation. At the time of diagnosis of RSDS, the mean serum creatinine was 1.4 mg/dL (range 1.0-1.7) and bone scintigraphy with 99mTc pyrophosphate showed increased uptake in all cases. The symptoms remitted 3-10 months after treatment (mean, 4 months) with calcitriol, with or without nifedipine or calcitonin, and in one case with suppression of sirolimus. We conclude that sirolimus therapy may induce RSDS in renal transplant recipients.

Abstract 3302: Contribution of Cardiac F-18 FDG PET Imaging to the Management of Patients with Cardiac Sarcoidosis

Early detection and correct assessment of disease activity are critical for the optimal management of patients with cardiac sarcoidosis (CSRD). There are some recent reports showing F-18 FDG (FDG) uptake by sarcoid granulomas. In the present study, we estimated the significance of cardiac FDG PET imaging in 47 patients (57+/−11 years, 16 males and 31 females) with proven diagnosis of CSRD and receiving steroid therapy (30 – 60 mg prednisolone on alternate days) based on clinical signs of acute myocardial involvement. We interpreted regionally enhanced myocardial FDG uptake as positive in the 5-hr fasting FDG PET imaging. In addition, we determined standardized uptake value (SUV) of the FDG uptake. Before steroid therapy, positive myocardial finding was 89% (42/47) in FDG PET, 55% (21/38) in Tc-99m pyrophosphate tomographic imaging, 68% (30/44) in Ga-67 tomographic imaging, 49% (23/47) in echocardiographically estimated septal wall thinning and 35% (13/37) in biopsy. SUV was above 2.5 in all with positive FDG finding. In 3 patients with severe heart failure and with positive finding in biopsy, myocardial FDG uptake showed diffuse patterns and was hardly interpreted positive. The follow-up studies after steroid therapy revealed that the enhanced FDG uptake gradually reduced and disappeared in 6 months in most of the patients, while positive Ga-67 uptake disappeared soon after therapy. Afterwards, recurrence of active inflammation was symptomatically suspected in 4 patients. Performing FDG PET imaging, they all showed re-enhancement of myocardial FDG uptake, which contributed to decision-making of increasing steroid dose. These results suggest that the FDG PET imaging is a sensitive means in detecting disease activity of CSRD and contributes to the decision-making and evaluation of steroid therapy.

Tc-99m pyrophosphate imaging of poloxamer-treated electroporated skeletal muscle in an in vivo rat model

Objective This study investigates whether 99mTc pyrophosphate (PYP) imaging provides a quantitative non-invasive assessment of the extent of electroporation injury, and of the effect of poloxamer in vivo on electroporated skeletal muscle. Methods High-voltage electrical shock was used to produce electroporation injury in an anesthetized rat's hind limb. In each experiment, the injured limb was treated intravenously by either poloxamer-188, dextran, or saline, and subsequently imaged with 99mTc PYP. The radiotracer's temporal behavior among the experimental groups was compared using curve fitting of time–activity curves from the dynamic image data. Results The washout kinetics of 99mTc PYP changed in proportion to the electric current magnitude that produced electroporation. Also, 99mTc PYP washout from electroporated muscle differed between poloxamer-188 treatment and saline treatment. Finally, 10-kDa dextran treatment of electroporated muscle altered 99mTc PYP washout less than poloxamer-188 treatment. Conclusions Behavior of 99mTc PYP in electroporated muscle appears to be an indicator of the amount of electroporation injury. Compared to saline, intravenous polaxamer-188 treatment reduced the amount of 99mTc PYP uptake. Coupled to results showing poloxamer-188 seals ruptured cellular membranes, lessens the extent of electroporation injury and improves cell viability, 99mTc PYP imaging appears to be a useful in vivo monitoring tool for the extent of electroporation injury.

Localization of Myocardial Amyloid Deposits in Cardiac Amyloidosis by Tc-99m Pyrophosphate Myocardial SPECT: Implication for Medical Treatment

A 69-year-old man with a recent history of aortic valve replacement was hospitalized for paradoxical increasing dyspnea and congestive heart failure. However, echocardiography showed no dysfunction of the prosthetic aortic valve. Planar radionuclide imaging demonstrated intense uptake of Tc-99m pyrophosphate within the myocardium. SPECT revealed biventricular abnormal uptake, mild in the right ventricular free wall and intense in the left ventricular septum and apex, suggesting amyloid deposits. Right heart catheterization found a “dip and plateau” diastolic pressure configuration and histology confirmed amyloidosis on myocardial biopsy. Diagnosis of amyloidosis had not been made by other noninvasive methods: ECG without low QRS voltage, echocardiography showing increased chamber size and concentric hypertrophy, but no infiltrating process in the ventricular walls.