The Role of Scintigraphy with Bone Radiotracers in Cardiac Amyloidosis.

Cardiac amyloidosis (CA) is caused by the myocardial deposition of misfolded proteins, either amyloid transthyretin (ATTR) or immunoglobulin light chains (AL). The paradigm of this condition has transformed, since CA is increasingly recognized as a relatively prevalent cause of heart failure. Cardiac scintigraphy with bone tracers is the unique noninvasive technique able to confirm CA without performing tissue biopsy or advanced imaging tests. A moderate-to-intense myocardial uptake (Perugini grade ≥2) associated with the absence of a monoclonal component is greater than 99% specific for ATTR-CA, while AL-CA confirmation requires tissue biopsy.

Prognostic impact of patients' management based on anatomic/functional phenotype: a study in patients with chronic coronary syndromes.

BACKGROUND: In stable coronary artery disease (CAD), the prognostic interaction between clinical variables and treatment appropriateness based on anatomic/functional phenotype needs to be evaluated. METHODS: 1585 consecutive patients underwent myocardial perfusion scintigraphy and coronary angiography within 90 days. Obstructive CAD (> 70% stenosis) with downstream moderate-to-severe ischemia (> 10%) was considered significant. Coronary revascularization was considered appropriate if all hemodynamically significant lesions were revascularized, while medical therapy only was deemed appropriate in the absence of hemodynamically significant CAD. RESULTS: Obstructive CAD and moderate-to-severe ischemia were documented in 1184 (75%) and 466 (29%) patients, respectively. Over mean follow-up of 4.7 ± 2.5 years, the primary endpoint (cardiac death and non-fatal myocardial infarction) occurred in 132 (8.2%) patients. Of patients with obstructive CAD, 797 (67%) were managed appropriately. Patients' management was inappropriate in 389 patients, because either non-hemodynamically significant lesions were revascularized (50%, including 2 patients with non-obstructive lesions being inappropriately revascularized) or ischemia-causing CAD was left untreated (50%). At multivariate analysis, an inappropriate management (P < .001) was correlated with the primary endpoint, together with previous myocardial infarction (P = .009), lower ejection fraction (P < .001) and higher glucose levels (P < .001). CONCLUSIONS: In stable CAD patients, management based on anatomic/functional phenotyping was correlated with a prognostic advantage at long-term follow-up. Correlation between treatment categories and patients' prognosis. A significantly higher event-rate was observed in patients where hemodynamically significant coronary lesions were left untreated-either because MT was not-adherently chosen or in the case of incomplete revascularization-than in those that were revascularized completely (17.6% vs 5.1%; P < .001). Conversely, the revascularization of non-hemodynamically significant CAD correlated with a higher event-rate than that of similar patients managed medically (13.8% vs 8.3%, P = .04). The event-rate of patients in whom coronary revascularization was performed in the presence of hemodynamically significant CAD ('appropriate revascularization') was similar to those with "No CAD/non-obstructive CAD" (5.1% vs 3.5%; P = NS).

Bayesian Convolutional Neural Networks in Medical Imaging Classification: A Promising Solution for Deep Learning Limits in Data Scarcity Scenarios.

Deep neural networks (DNNs) have already impacted the field of medicine in data analysis, classification, and image processing. Unfortunately, their performance is drastically reduced when datasets are scarce in nature (e.g., rare diseases or early-research data). In such scenarios, DNNs display poor capacity for generalization and often lead to highly biased estimates and silent failures. Moreover, deterministic systems cannot provide epistemic uncertainty, a key component to asserting the model's reliability. In this work, we developed a probabilistic system for classification as a framework for addressing the aforementioned criticalities. Specifically, we implemented a Bayesian convolutional neural network (BCNN) for the classification of cardiac amyloidosis (CA) subtypes. We prepared four different CNNs: base-deterministic, dropout-deterministic, dropout-Bayesian, and Bayesian. We then trained them on a dataset of 1107 PET images from 47 CA and control patients (data scarcity scenario). The Bayesian model achieved performances (78.28 (1.99) % test accuracy) comparable to the base-deterministic, dropout-deterministic, and dropout-Bayesian ones, while showing strongly increased "Out of Distribution" input detection (validation-test accuracy mismatch reduction). Additionally, both the dropout-Bayesian and the Bayesian models enriched the classification through confidence estimates, while reducing the criticalities of the dropout-deterministic and base-deterministic approaches. This in turn increased the model's reliability, also providing much needed insights into the network's estimates. The obtained results suggest that a Bayesian CNN can be a promising solution for addressing the challenges posed by data scarcity in medical imaging classification tasks.

18-FDG PET for large vessel vasculitis diagnosis and follow-up.

OBJECTIVES: Large vessel vasculitis (LVV) are chronic inflammatory diseases that affect arteries. While a mere clinical-serological approach does not seem sensitive either in the initial evaluation nor in long-term monitoring, 18-FDG positron emission tomography (18-FDG PET) is currently considered a useful assessment tool in LVV. We aimed at exploring the utility of 18-FDG, compared with traditional assessments, in the short- and long-term follow-up of patients with LVV. In addition, we compared patterns of vascular involvement in patients with Takayasu's arteritis (TAK) and giant cell arteritis (GCA). METHODS: We retrospectively analysed 47 patients affected by LVV, evaluating clinics, blood chemistry and 18-FDG PET results, at two time points, short-term (average 8 months after diagnosis) and long-term (average 29 months). RESULTS: 18-FDG PET uptake, expressed as mean value of SUV max, decreased significantly during follow-up in all the patients. A low concordance between 18-FDG PET and acute phase reactants levels was observed, but also a good sensitivity in detecting the response to treatment. CONCLUSIONS: The results confirm the role of 18-FDG PET as a powerful tool in the evaluation of LVV, both at the time of diagnosis and during monitoring. Furthermore, the data confirm that GCA and TAK are part of the same disease spectrum.

Stress-induced alteration of left ventricular eccentricity: An additional marker of multivessel CAD.

BACKGROUND: Abnormal left ventricular (LV) eccentricity index (EI) is a marker of adverse cardiac remodeling. However, the interaction between stress-induced alterations of EI and major cardiac parameters has not been explored. We sought to evaluate the relationship between LV EI and coronary artery disease (CAD) burden in patients submitted to myocardial perfusion imaging (MPI). METHODS AND RESULTS: Three-hundred and forty-three patients underwent MPI and coronary angiography. LV ejection fraction (EF) and EI were computed from gated stress images as measures of stress-induced functional impairment. One-hundred and thirty-six (40%), 122 (35%), and 85 (25%) patients had normal coronary arteries, single-vessel CAD, and multivessel CAD, respectively. Post-stress EI was lower in patients with multivessel CAD than in those with normal coronary arteries and single-vessel CAD (P = 0.001). This relationship was confirmed only in patients undergoing exercise stress test, where a lower post-stress EI predicted the presence of multivessel CAD (P = 0.039). CONCLUSIONS: Post-stress alterations of LV EI on MPI may unmask the presence of multivessel CAD.

Accuracy of 99mTc-Hydroxymethylene diphosphonate scintigraphy for diagnosis of transthyretin cardiac amyloidosis.

BACKGROUND AND AIM: Either 99mTechnetium diphosphonate (Tc-DPD) or pyrophosphate (Tc-PYP) scintigraphy plays a relevant role in diagnosing transthyretin cardiac amyloidosis (CA), and labeled radiotracers have been extensively studied in diagnosing CA. Few studies have analyzed and validated 99mTc-Hydroxymethylene diphosphonate (Tc-HMDP). Our aim was to validate the diagnostic accuracy of Tc-HMDP total-body scintigraphy in a cohort of patients with biopsy-proven transthyretin CA. METHODS AND RESULTS: We retrospectively evaluated all patients undergoing 99mTc-HMDP total-body scintigraphy, in adjunct to a comprehensive diagnostic work-up for suspected CA. Sixty-five patients were finally diagnosed with CA, while it was excluded in 20 subjects with left ventricular hypertrophy of various etiologies. Twenty-six patients had AL-CA, 39 had TTR CA (16 TTRm, 23 TTRwt). At Tc-HMDP scintigraphy, 2 AL patients showed a Perugini score grade 1 heart uptake, while 24 showed no uptake. All TTR patients showed Tc-HMDP uptake, with three patients showing a Perugini score grade 1, 16 grade 2, and 20 grade 3, respectively. No uptake was observed in patients with left ventricular hypertrophy. A positive Tc-HMDP scintigraphy showed a 100% sensitivity and a 96% specificity for TTR CA identification. CONCLUSIONS: Tc-HMDP scintigraphy is as accurate as Tc-DPD or Tc-PYP, and may therefore de facto be considered a valuable tool for the diagnosis of TTR CA.

Effect of prolonged fasting and low molecular weight heparin or warfarin therapies on 2-deoxy-2-[18F]-fluoro-D-glucose PET cardiac uptake.

BACKGROUND: Whether anticoagulants other than unfractionated heparin are able to suppress cardiac PET uptake of 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) is unknown. METHODS: One-hundred-seventy-four patients without history and clinical evidence of cardiac dysfunction and/or coronary heart disease underwent a 18F-FDG PET/CT study. All patients were studied with a >12-hours fasting and divided into 2 groups: group-1 without anticoagulant therapy (n:75); group-2 patients on low molecular weight heparin (n:60) or warfarin therapy (n:39). Cardiac 18F-FDG uptake was estimated qualitatively using a 4-point scale and semiquantitatively as total LV glycolysis (LVG) and metabolic volume (MV), drawing isocontour volume of interest (VOI) including the whole LV. RESULTS: Qualitatively, LV 18-FDG uptake was scored 0 or 1, indicating a good suppression, in 10/75 (13%) patients of group-1 and 77/99 (78%) of group-2 (p < .001). Semiquantitatively, patients of group-1 showed higher values of 18-FDG uptake than patients of group-2, assessed as LVG (802,649 ± 468,442 vs 198,989 ± 261,439, p < .0001) or MV (219 ± 77 vs 57 ± 48 cm3, p < .0001). Subanalysis for anticoagulant drugs showed similar results. CONCLUSIONS: Prolonged fasting combined to anticoagulants other than unfractionated heparin is able to minimize glucose cardiac metabolism. Our data confirm previous observation on the possibility to influence the metabolic pattern of the heart before the PET scan and broadens the spectrum of pharmacological options.

Food addiction distinguishes an overweight phenotype that can be reversed by low calorie diet.

Similarities in neural activation patterns in obese and substance-dependent subjects led to the food addiction concept, but studies exploiting this issue for obesity stratification are missing. We assessed brain activation in response to food cues using 18 F-2-fluoro-2-deoxy-glucose-PET in 36 overweight women, stratified by low or high food addiction groups according to the Yale Food Addiction Scale (YFAS). Assessments were repeated after a 3-month diet. We found greater activation in thalamus, hypothalamus, midbrain, putamen, and occipital cortex (reward), but not in prefrontal and orbitofrontal cortices (control/reward receipt) in the high-YFAS versus low-YFAS group. In high-YFAS subjects, orbitofrontal responsiveness was inversely related to YFAS severity and hunger rating, and positive associations were observed between regional brain activation and lipid intake. A 3-month diet abolished group differences in brain activation. Our data suggest that food addiction distinguishes an overweight phenotype that can be reversed by diet, opening to personalized strategies in obesity treatment.

PET-CT evaluation of amyloid systemic involvement with [18F]-florbetaben in patient with proved cardiac amyloidosis: a case report.

BACKGROUND: One of the most frequent disorders which lead to cardiac amyloidosis is transthyretin-related amyloidosis (ATTR). Some PET radio-pharmaceuticals for the detection of beta-amyloid deposits within the brain have shown to be able to detect also cardiac amyloid deposits. We present a case of a man with ATTR studied with [18F]-florbetaben PET-CT. RESULTS: Total-body scan showed a moderate uptake in the bone marrow, especially in correspondence of the vertebral column, while no significant myocardial uptake was present. Cardiac-focused scans showed low mean cardiac SUV values confirming the absence of significant myocardial uptake. Brain scan showed a significant cortical brain uptake of the radio-pharmaceutical more evident in correspondence of frontal and temporal lobes. CONCLUSIONS: Distinct subtypes of amyloidosis show different uptake of the radiotracer. Brain amyloid deposition in the presence of a systemic disease could not be caused by the same amyloid precursor.

Determinants of left ventricular mechanical dyssynchrony in patients submitted to myocardial perfusion imaging: A cardiac CZT study.

BACKGROUND: An interaction between coronary anatomy, myocardial perfusion, and left ventricular (LV) functional parameters in the development of mechanical LV dyssynchrony (LVD) has been suggested. This study examined the correlates of LVD in a large sample size of patients with known or suspected coronary artery disease (CAD) using cadmium-zinc-telluride camera. METHODS: Six-hundred and fifty-seven consecutive patients who underwent myocardial perfusion imaging (MPI) and coronary angiography were included. Coronary stenosis >70% was considered significant. LV perfusion and functional parameters were computed from MPI images. The presence of significant LVD was evaluated by phase standard deviation and histogram bandwidth. RESULTS: 415/657 (63%) patients had significant CAD. LVD was present in 247 (38%) patients and was associated with the presence of a higher CAD burden (P < .001), more impaired measures of LV perfusion (P < .001), contractile function (P < .001), and larger LV volumes (P < .001). By multivariate analysis, the LV end-systolic volume index (P < .001) and ischemic burden (P < .001) were the strongest predictors of LVD independent of CAD extent and LV systolic dysfunction. CONCLUSIONS: LVD is frequent in patients undergoing MPI for suspected or known CAD. Its presence is independent of CAD burden and LV systolic dysfunction, but is dependent on the presence of myocardial perfusion abnormalities and LV end-systolic volume.

Relationships between myocardial perfusion abnormalities and poststress left ventricular functional impairment on cadmium-zinc-telluride imaging.

PURPOSE: To evaluate the interplay between myocardial ischaemic burden and poststress left ventricular (LV) systolic and diastolic abnormalities in patients with suspected or known coronary artery disease (CAD). METHODS: A total of 471 patients underwent myocardial perfusion imaging by cadmium-zinc-telluride scintigraphy and coronary angiography. A fast imaging protocol was used with stress imaging performed 10 - 15 min after tracer injection. The summed difference score (SDS) and the percent stress-to-rest ratios for LV ejection fraction and peak filling rate (PFR), measures of stress-induced systolic and diastolic impairment, were computed from scintigraphic images. A SDS of >3 was considered abnormal and >7 a marker of moderate-to-severe ischaemia. RESULTS: Of the 471 patients, 321 (68%) showed significant CAD in one (27%), two (23%) or three (18%) vessels. The extent of CAD associated with gradual alterations in SDS (P < 0.001). Interestingly, while impairment in the percent stress-to-rest PFR ratio paralleled the increase in the extent of CAD (P < 0.001 for trend), the occurrence of significant stress-induced systolic dysfunction was limited to patients with multivessel disease (P < 0.001 vs. patients without CAD, and P = 0.002 vs. patients with single-vessel disease). Similarly, while a strict correlation between percent stress-to-rest PFR ratio and myocardial ischaemic burden was evident (P < 0.001), significant stress-induced LV systolic impairment was limited to patients with moderate-to-severe ischaemia (P < 0.001 vs. patients with no or mild ischaemia). CONCLUSION: Stress-induced LV diastolic impairment is associated with a less extensive ischaemic burden and CAD extent than poststress systolic dysfunction, which is limited to patients with multivessel CAD.

Feasibility of [(123)I]-meta-iodobenzylguanidine dynamic 3-D kinetic analysis in vivo using a CZT ultrafast camera: preliminary results.

PURPOSE: No data are yet available in the literature concerning 3-D [(123)I]-meta-iodobenzylguanidine ([(123)I]-MIBG) kinetics in vivo. In this study we investigated the feasibility of dynamic 3-D [(123)I]-MIBG kinetic analysis using a CZT ultrafast camera. METHODS: The study group comprised 16 patients consecutively scheduled for [(123)I]-MIBG cardiac scintigraphy for clinical purpose who were studied using a CZT camera (NM530c, GE). Dynamic acquisition in list mode was simultaneously started with a bolus injection of the radiotracer (185-370 MBq) for an overall duration of 900 s. A temporal series of 3-D volumes was reconstructed from the first 150 s of dynamic acquisition with a temporal resolution of 5 s. A summed cardiac image was also reconstructed to serve as reference for blood pool (BP) and left ventricle (LV) wall identification. BP and LV volumes of interest (VOIs) were manually drawn to cover the whole heart and automatically reported on the reframed volumes. Time-activity curves (TACs) for the BP and LV were extracted by averaging the signal intensity in the respective VOI in each time frame. BP TACs were fitted to a gamma variate model while LV TACs were fitted to a bicompartmental model. RESULTS: TAC analysis was feasible in all patients with good interobserver reproducibility. BP TACs were well described by a gamma variate model as they represent the first pass of the tracer. The first compartment of LV TACs corresponded to contamination spillover of the LV signal from the BP signal. The LV second compartment characterized the uptake of the tracer in the myocardium quantified in terms of maximum signal intensity value (6.95 ± 2.76 counts/mm(3)/s(2)), maximum up-slope value (0.36 ± 0.15 counts/mm(3)/s) and normalized washout of the signal value (7.0 ± 0.6 %). CONCLUSION: Using CZT technology and dynamic 3-D acquisition, analysis of [(123)I]-MIBG radiotracer kinetics in vivo is feasible and may provide pathophysiological information in addition to that available with standard planar and SPECT imaging.

Association between left ventricular regional sympathetic denervation and mechanical dyssynchrony in phase analysis: a cardiac CZT study.

PURPOSE: To evaluate the relationships among myocardial sympathetic innervation, perfusion and mechanical synchronicity assessed with cardiac cadmium-zinc-telluride (CZT) scintigraphy. METHODS: A group of 29 patients underwent an evaluation of myocardial perfusion with (99m)Tc-tetrofosmin CZT scintigraphy and adrenergic innervation with (123)I-metaiodobenzylguanidine (MIBG) CZT scintigraphy. The summed rest score (SRS), motion score (SMS) and thickening score (STS), as well as the summed (123)I-MIBG defect score (SS-MIBG), were determined. Regional tracer uptake for both (99m)Tc-tetrofosmin and (123)I-MIBG was also calculated. Finally, the presence of significant myocardial mechanical dyssynchrony was evaluated in phase analysis on gated CZT images and the region of latest mechanical activation identified. RESULTS: Significant mechanical dyssynchrony was present in 17 patients (59 %) and associated with higher SRS (P = 0.030), SMS (P < 0.001), STS (P = 0.003) and early SS-MIBG (P = 0.037) as well as greater impairments in left ventricular ejection fraction (P < 0.001) and end-diastolic volume (P < 0.001). In multivariate analysis a higher end-diastolic volume remained the only predictor of mechanical dyssynchrony (P = 0.047). Interestingly, while in the whole population regional myocardial perfusion and adrenergic activity were strongly correlated (R = 0.68), in patients with mechanical dyssynchrony the region of latest mechanical activation was predicted only by greater impairment in regional (123)I-MIBG uptake (P = 0.012) that overwhelmed the effect of depressed regional perfusion. CONCLUSION: Left ventricular mechanical dyssynchrony is associated with greater depression in contractile function and greater impairments in regional myocardial perfusion and sympathetic activity. In patients with dyssynchrony, the region of latest mechanical activation is characterized by a significantly altered adrenergic tone.

Relationship between myocardial perfusion abnormalities and contractile impairment in anginal patients.

BACKGROUND: A relationship between left ventricular (LV) contractile impairment and myocardial perfusion abnormalities has been suggested. METHODS AND RESULTS: Three-hundred and thirty-seven patients underwent myocardial perfusion imaging at CZT and coronary angiography. On scintigraphic images, the summed difference score (SDS) and LV-ejection fraction (EF) were computed. Patients were categorized as follows: Group-1 (LV-EF < 40%; 71 patients), Group-2 (LV-EF ≥ 40% and < 55%; 77 patients), and Group-3 (LV-EF ≥ 55%; 189 patients). Significant coronary artery disease (CAD; ≥50% stenosis) was recognized in 159/337 (47%) patients. Interestingly, while in Group-3 subjects an inverse relationship between SDS values and post-stress LV-EF was evident (P < .001), Group-1 patients presented a significant association between an increased SDS and more elevated post-stress LV-EF values (P = .009). Similarly, despite in the overall population an increasing severity of CAD was associated with higher SDS values (P < .001), this relationship disappeared in Group-1 patients (P = .298). At multiple regression analysis, after correction for CAD, LV dysfunction was negatively associated with an elevated SDS (P = .018). Conversely in patients with normal LV function and no history of myocardial infarction, CAD extent, and functional measures of stress-induced myocardial ischemia were strictly correlated. CONCLUSIONS: Independently from CAD, a significantly impaired LV function associates with a lower prevalence of reversible ischemia.

Wild-Type Transthyretin Cardiac Amyloidosis is Not Rare in Elderly Subjects: the CATCH Screening Study.

BACKGROUND: Wild-type transthyretin cardiac amyloidosis (ATTRwt-CA) affects older adults and is currently considered as a rare disorder. OBJECTIVE: We investigated for the first time the prevalence of ATTRwt-CA in elderly individuals from the general population. METHODS: General practitioners from Pisa, Italy, proposed a screening for ATTRwt-CA to all their patients aged 65-90 years, until 1,000 accepted. The following red flags were searched: interventricular septal thickness ≥12 mm, any echocardiographic, ECG or clinical hallmark of CA, or high sensitivity-troponin T ≥14 ng/L. Individuals with at least one red flag (n=346) were asked to undergo the search for a monoclonal protein and bone scintigraphy, and 216 accepted. RESULTS: Four patients received a non-invasive diagnosis of ATTRwt-CA. All complained of dyspnea on moderate effort. A woman and a man aged 79 and 85 years, respectively, showed an intense cardiac tracer uptake (grade 3), left ventricular (LV) wall thickening, grade 2 to 3 diastolic dysfunction, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) >1,000 ng/L. Two other patients (a man aged 74 years and a woman aged 83 years) showed a grade 2 uptake, an increased LV septal thickness, but preserved diastolic function, and NT-proBNP <300 ng/L. The prevalence of ATTR-CA in subjects ≥65 years was calculated as 0.46% (i.e., 4 out of the 870 subjects completing the screening, namely 654 not meeting the criteria for Step 2 and 216 progressing to Step 2). CONCLUSIONS: ATTRwt-CA is uncommon in elderly subjects from the general population, but more frequent than expected for a rare disease.

Wild-type transthyretin cardiac amyloidosis (ATTRwt-CA) is a heart condition mostly found in older adults. ATTRwt-CA is considered a rare disease, although no systematic screening have been performed yet. The study aimed to understand how common this disease is among the general population aged 65 to 90 years in Pisa, Italy. To do this, general practitioners offered screening for ATTRwt-CA to their patients within this age group. The initial step of the screening involved checking for certain warning signs (red flags), like abnormal thickness in a part of the heart called the interventricular septum, unusual heart function observed through various tests, or elevated levels of a specific heart protein. Out of 1,000 individuals who began the screening process, 346 showed at least one of these red flags and were further examined using bone scintigraphy (a type of imaging test) and tests for a specific protein related to this condition. Of these, 216 agreed to proceed with these additional tests. The results showed that four of these patients actually had ATTRwt-CA. Their conditions varied in severity, with some showing more intense signs of the disease on the heart scans, thicker heart walls, and higher levels of heart stress proteins. All four patients experienced mild difficulty in breathing during physical activity. Based on these findings, the study concluded that about 0.46% of elderly individuals in the general population might have ATTRwt-CA, indicating that the disease is somewhat more common in this age group than previously thought.

Gender differences in the evaluation of coronary artery disease with a cadmium-zinc telluride camera.

PURPOSE: Coronary artery disease remains one of the most significant causes of morbidity and mortality among women. The published literature shows the importance of standard single photon emission computed tomography in the evaluation of women with known or suspected ischaemic heart disease, in terms of target intervention and clinical treatment. The purpose of the present study was to ascertain the diagnostic accuracy of cadmium-zinc-telluride (CZT) myocardial perfusion imaging according to gender, within a prospective database of patients with known or suspected coronary artery disease, using coronary angiography as the reference standard. METHODS: Included in the study were 309 consecutive patients, of whom 248 were men (80 %), with known or suspected coronary artery disease and who had been referred to our laboratory for stress-rest myocardial perfusion imaging. All patients underwent coronary angiography within 30 days. All patients underwent a single-day stress-rest low-dose ultrafast protocol. Fifteen minutes after the end of the stress (dose range 185 to 222 MBq of (99m)Tc-tetrofosmin), all patients underwent the first scan with an acquisition time of 7 min. The rest scan (dose range 370 to 444 MBq of (99m)Tc-tetrofosmin) was acquired from 30 min to 45 min after injection, with an acquisition time of 6 min. Images were visually inspected, and summed stress scores (SSS) and summed rest scores (SRS) were obtained. RESULTS: Image quality was graded "good" or better in more than 90 % of patients. On coronary angiography, left main trunk stenosis, left anterior descending artery stenosis, left circumflex artery stenosis and right coronary artery stenosis were seen in 3, 155 , 142 and 131 patients, respectively. In women, the mean SSS and SRS were 8 ± 5 and 3 ± 1, respectively. Semiquantitative regional and global SSS were good discriminants of coronary artery disease, and the overall area under the receiver operator characteristic (ROC) curve was 0.822 (95 % CI 0.685 - 0.959). The value was comparable to that obtained in men (overall ROC area 0.884, 95 % CI 0.836 - 0.933). CONCLUSION: A low-dose protocol with a CZT camera can be routinely used in women with known or suspected coronary artery disease without loss of accuracy and with lower radiation exposure of the patients.

Gated SPECT evaluation of left ventricular function using a CZT camera and a fast low-dose clinical protocol: comparison to cardiac magnetic resonance imaging.

PURPOSE: CZT technology allows ultrafast low-dose myocardial scintigraphy but its accuracy in assessing left ventricular function is still to be defined. METHODS: The study group comprised 55 patients (23 women, mean age 63 ± 9 years) referred for myocardial perfusion scintigraphy. The patients were studied at rest using a CZT camera (Discovery NM530c; GE Healthcare) and a low-dose (99m)Tc-tetrofosmin clinical protocol (mean dose 264 ± 38 MBq). Gated SPECT imaging was performed as a 6-min list-mode acquisition, 15 min after radiotracer injection. Images were reformatted (8-frame to 16-frame) using Lister software on a Xeleris workstation (GE Healthcare) and then reconstructed with a dedicated iterative algorithm. Analysis was performed using Quantitative Gated SPECT (QGS) software. Within 2 weeks patients underwent cardiac magnetic resonance imaging (cMRI, 1.5-T unit CVi; GE Healthcare) using a 30-frame acquisition protocol and dedicated software for analysis (MASS 6.1; Medis). RESULTS: The ventricular volumes obtained with 8-frame QGS showed excellent correlations with the cMRI volumes (end-diastolic volume (EDV), r = 0.90; end-systolic volume (ESV), r = 0.94; p < 0.001). However, QGS significantly underestimated the ventricular volumes (mean differences: EDV, -39.5 ± 29 mL; ESV, -15.4 ± 22 mL; p < 0.001). Similarly, the ventricular volumes obtained with 16-frame QGS showed an excellent correlations with the cMRI volumes (EDV, r = 0.92; ESV, r = 0.95; p < 0.001) but with significant underestimations (mean differences: EDV, -33.2 ± 26 mL; ESV, -17.9 ± 20 mL; p < 0.001). Despite significantly lower values (47.9 ± 16 % vs. 51.2 ± 15 %, p < 0.008), 8-frame QGS mean ejection fraction (EF) was closely correlated with the cMRI values (r = 0.84, p < 0.001). The mean EF with 16-frame QGS showed the best correlation with the cMRI values (r = 0.91, p < 0.001) and was similar to the mean cMRI value (49.6 ± 16 %, p not significant). Regional analysis showed a good correlation between both 8-frame and 16-frame QGS and cMRI wall motion score indexes (8-frame WMSI, r = 0.85; 16-frame WMSI, r = 0.89; p < 0.01). CONCLUSION: Low-dose gated SPECT with a CZT camera provides ventricular volumes that correlate well with cMRI results despite significant underestimation in the measure values. EF estimation appeared to be more accurate with 16-frame reformatted images than with 8-frame images.

Sex-specific associations of myocardial perfusion imaging with outcomes in patients with suspected chronic coronary syndrome.

BACKGROUND: Myocardial perfusion scintigraphy (MPS) is an established diagnostic technique for inducible ischemia in patients with suspected chronic coronary syndrome (CCS). Some MPS findings, most notably an ischemia extent>10% of the left ventricle (LV), hold prognostic significance and support maximization of anti-ischemic treatment. We aimed to assess sex-specific associations of MPS findings with cardiovascular (CV) events in a population at high risk of CCS. METHODS: In a prospective cohort study, 1,229 consecutive patients (age 70 ± 9.5 years, 73.5% males) without known CCS were referred to stress-rest MPS. All patients were followed for a median of 4.6 years for CV events. RESULTS: Men and women had comparable risk profiles and incidence rates of CV events (6.6% vs. 4.6% respectively, P = 0.186). A summed stress score (SSS) > 7 was associated with the primary endpoint, including CV death and/or nonfatal myocardial infarction (MI) (adjusted hazard ratio [HR], 3.13; 95% confidence interval [CI], 1.79-5.46; P = 0.001), all-cause mortality (HR, 3.01; 95% CI, 1.31-6.93; P = 0.01), and incidence of late revascularization (HR, 1.84; 95% CI, 1.22-2.78; P = 0.004) in men but not women. A summed difference score (SDS) > 6 was related to a higher rate of the primary endpoint only in men (adjusted HR, 1.97; 95% CI, 1.18-3.30; P = 0.009). CONCLUSIONS: Among patients undergoing a diagnostic workup for suspected CCS, stress perfusion and reversible ischemia abnormalities may independently predict worse survival and more CV events in men. However, the obtained results indicated the need for sex-specific cutoffs to refine risk stratification and assist in clinical decisions on anti-ischemic therapy beyond coronary artery anatomy.