Cardiac Imaging Update

Resting electrocardiogram and stress myocardial perfusion imaging in the determination of left ventricular systolic function: an assessment enhancing the performance of gated SPET.

Hell J Nucl Med. 2010 May-Aug;13(2):118-26

Authors: Moralidis E, Spyridonidis T, Arsos G, Skeberis V, Anagnostopoulos C, Gavrielidis S

This study aimed to determine systolic dysfunction and estimate resting left ventricular ejection fraction (LVEF) from information collected during routine evaluation of patients with suspected or known coronary heart disease. This approach was then compared to gated single photon emission tomography (SPET). Patients having undergone stress (201)Tl myocardial perfusion imaging followed by equilibrium radionuclide angiography (ERNA) were separated into derivation (n=954) and validation (n=309) groups. Logistic regression analysis was used to develop scoring systems, containing clinical, electrocardiographic (ECG) and scintigraphic data, for the discrimination of an ERNA-LVEF<0.50. Linear regression analysis provided equations predicting ERNA-LVEF from those scores. In 373 patients LVEF was also assessed with (201)Tl gated SPET. Our results showed that an ECG-Scintigraphic scoring system was the best simple predictor of an ERNA-LVEF<0.50 in comparison to other models including ECG, clinical and scintigraphic variables in both the derivation and validation subpopulations. A simple linear equation was derived also for the assessment of resting LVEF from the ECG-Scintigraphic model. Equilibrium radionuclide angiography-LVEF had a good correlation with the ECG-Scintigraphic model LVEF (r=0.716, P=0.000), (201)Tl gated SPET LVEF (r=0.711, P=0.000) and the average LVEF from those assessments (r=0.796, P=0.000). The Bland-Altman statistic (mean+/-2SD) provided values of 0.001+/-0.176, 0.071+/-0.196 and 0.040+/-0.152, respectively. The average LVEF was a better discriminator of systolic dysfunction than gated SPET-LVEF in receiver operating characteristic (ROC) analysis and identified more patients (89%) with a

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Incidental detection of skeletal metastases from thyroid cancer during myocardial perfusion imaging.

Hell J Nucl Med. 2010 May-Aug;13(2):169-70

Authors: Kashyap R, Balasubramanian Harisankar CN, Parmar M, Bhattacharya A, Singh B, Mittal BR

To the Editor: The HJNM has published cases of various incidental findings on myocardium perfusion imaging (MPI). We report another incidental finding on MPI that may be important for the treatment schedule of the patients studied. A 65 years old female patient with follicular thyroid cancer was subjected to stress MPI using technetium-99m tetrofosmin ((99m)Tc-TF) in order to exclude coronary artery disease, as part of tests performed before anaesthesia and total thyroidectomy. She was hypertensive and diabetic and complained of symptoms equivalent to angina. Cardiac stress was given with dobutamine, starting with a dose of 10mcg/kg to a maximum of 40mcg/kg. (99m)Tc-TF was injected 1min before discontinuing the infusion of dobutamine. A second injection comprising 777MBq of the radiotracer was administered after 3hrs at rest. Abnormal tracer accumulation was noted adjoining the myocardium, in both stress and rest images. A lateral image acquired in prone position with the breast hanging did not show any abnormal uptake in the breast tissue. Another focus of abnormally increased tracer uptake, at the site of a palpable swelling, was noticed in the occipital region. Subsequent whole body imaging was performed using the already injected dose, of (99m)Tc-TF for rest MPI that showed one more focus of faint tracer uptake at the left pelvic region. Single photon emission tomography /computerized tomography (SPET/CT) examination of the thoracic region with (99m)Tc-TF injected for rest MPI localized the abnormal focus to be in the 4th left rib near the costochondral junction. No hybrid imaging was performed for the pelvic focus after the MPI. The patient was subjected to total thyroidectomy and metastasectomy of metastasis at the skull. A whole body iodine-131 ((131)I) scan performed 48h after oral administration of 55.5MBq of (131)I showed residual tracer uptake at the occipital region, a focal tracer uptake in the chest and another focus in the pelvis. Hybrid imaging localized the tracer uptake in the pelvis, at the acetabular margin. Several case reports of incidental extracardiac uptake of the radiotracer have been reported in the literature. Metastases from thyroid cancer to the skull are seen in approximately 2.5%-5.8% of these cases, while skeletal metastases are seen in approximately 10%-40%. The patient was further treated with (131)I as all metastases were iodine avid. Due to the diagnosis of multiple skeletal metastases the (131)I dose was increased to 150mCi. The patient is on regular follow up and is doing well.In conclusion, incidental findings in MPI performed by hybrid SPET/CT showed skeletal metastases of thyroid cancer and altered treatment procedure.

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Chronic kidney disease and risk for coronary events: Value of myocardial perfusion imaging.

J Nucl Cardiol. 2010 Sep 2;

Authors: Beller GA

20811968

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Atrial and Ventricular Functional and Structural Adaptations of the Heart in Elite Triathletes Assessed with Cardiac MR Imaging.

Radiology. 2010 Aug 31;

Authors: Scharf M, Brem MH, Wilhelm M, Schoepf UJ, Uder M, Lell MM

Purpose: To assess cardiac morphologic and functional adaptations in elite triathletes with magnetic resonance (MR) imaging and to compare findings to those in recreationally active control subjects. Materials and Methods: The institutional review board approved the study, and written informed consent was obtained from all subjects. Twenty-six male triathletes (mean age +/- standard deviation, 27.9 years +/- 3.5; age range, 18-35 years) and 27 nonathletic male control subjects (mean age, 27.3 years +/- 3.7; age range, 20-34 years) underwent cardiac MR imaging. Electrocardiographically gated steady-state free-precession cine MR imaging was used to measure indexed left ventricular (LV) and right ventricular (RV) myocardial mass, end-diastolic and end-systolic volumes, stroke volume, ejection fraction (EF), and cardiac index at rest. The ventricular remodeling index, which is indicative of the pattern of cardiac hypertrophy, was calculated. The maximum left atrial (LA) volume was calculated according to the biplane area-length method. Differences between means of athletes and control subjects were assessed by using the Student t test for independent samples. Results: The atrial and ventricular volume and mass indexes in triathletes were significantly greater than those in control subjects (P < .001). In 25 of the 26 athletes, the LV and RV end-diastolic volumes were greater than the normal ranges reported in the literature for healthy, male, nonathletic control subjects (47-92 mL/m(2) and 55-105 mL/m(2), respectively). There was a strong positive correlation between end-diastolic volume and myocardial mass (P < .01). The mean LV and RV remodeling indexes of the athletes (0.73 g/mL +/- 0.1 and 0.22 g/mL +/- 0.01, respectively) were similar to those of the control subjects (0.71 g/mL +/- 0.1 [P = .290] and 0.22 g/mL +/- 0.01 [P = .614], respectively). There was a negative correlation between LA end-systolic volume and heart rate (P < .01). Conclusion: Changes in cardiac morphologic characteristics and function in elite triathletes, as measured with cardiac MR imaging, reflect a combination of eccentric and concentric remodeling with regulative enlargement of atrial and ventricular chambers. These findings are different from what has been observed in previous studies in other types of elite athletes. (c) RSNA, 2010.

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A Strategic Approach for Cardiac MR Left Ventricle Segmentation.

Cardiovasc Eng. 2010 Aug 31;

Authors: Dakua SP, Sahambi JS

Quantitative evaluation of cardiac function from cardiac magnetic resonance (CMR) images requires the identification of the myocardial walls. This generally requires the clinician to view the image and interactively trace the contours. Especially, detection of myocardial walls of left ventricle is a difficult task in CMR images that are obtained from subjects having serious diseases. An approach to automated outlining the left ventricular contour is proposed. In order to segment the left ventricle, in this paper, a combination of two approaches is suggested. Difference of Gaussian weighting function (DoG) is newly introduced in random walk approach for blood pool (inner contour) extraction. The myocardial wall (outer contour) is segmented out by a modified active contour method that takes blood pool boundary as the initial contour. Promising experimental results in CMR images demonstrate the potentials of our approach.

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