Evaluation of left ventricular wall motion and function in patients with previous myocardial infarction by three-dimensional 99mTc-HSAD multigated cardiac pool imaging

Erythrocytes labeled with [(18) F]SFB as an alternative to radioactive CO for quantification of blood volume with PET

Inhaled radioactive CO is currently the tracer of choice for blood volume quantification by positron emission tomography (PET). This measurement is of great interest for several clinical and research applications. However, owing to the short half-life of the radiolabeled CO, it can only be used in centers equipped with a cyclotron. In the present work, we propose an alternative method to label the red blood cells with [(18) F] in order to obtain blood volume measurements by PET. The use of the radioactive synthon [(18) F] N-succinimidyl 4-[(18) F]fluorobenzoate ([(18) F]SFB) was evaluated for erythrocyte labeling and PET blood volume imaging. The images provided by [(18) F]SFB labeled erythrocytes were compared with those obtained with inhaled [(11) C]CO. Blood volumes obtained with [(18) F]SFB labeled erythrocytes were similar to those obtained with [(11) C]CO in all of the evaluated organs with the exception of spleen, which presented lower uptake with this method. Since the [(18) F]-SFB binds irreversibly to red blood cells, in vivo stability of the radiolabel was higher compared with the [(11) C]CO method. Additionally, owing to the longer half-life and the shorter positron range of [(18) F], the image quality was also higher with the [(18) F]SFB radiolabeled erythrocytes. The labeling of red blood with [(18) F]SFB represents an advantageous alternative to radioactive CO for blood volume measurement by PET and cardiovascular isotopic imaging.

Regional analysis of the left ventricle of the heart

This paper presents a method to analyze the local wall motion of the left ventricle of the heart. Data are sets of points (obtained from various medical imaging modalities) corresponding to surfaces of the left ventricle, which evolve as a function of time. After re-sampling, the surfaces are segmented in order to create regions of equivalent volume. Then, the local cardiac parameters are estimated: evolution of the regional volumes as a function of time, ejection fraction, end-diastolic and end-systolic volumes, end-diastolic and end-systolic instants. The method has been validated using deformable surfaces synthesized from an ellipsoidal model. It has also been tested in vivo on a set of 59 patients using a specially developed software product, which satisfies severe constraints of robustness, real-time, interactivity and ergonomics. The results obtained are similar to those provided by a reference nuclear medicine examination, but the proposed method is faster and gives a more precise localization of the cardiac wall motion anomalies.

Volume measurements in nuclear medicine gated SPECT and 4D echocardiography: validation using a dynamic cardiac phantom

PURPOSE

A dynamic cardiac phantom was used as a reference to compare volumes measured with gated SPECT and 4D echocardiography.

MATERIAL AND METHODS

Gated SPECT data were acquired with a standard single-head gamma camera, and the volume reconstructions were carried out using the Mirage software by Segami. 4D echocardiography used a new prototype of rotating scan head to acquire ultrasound images during a cardiac cycle, used to reconstruct the volume deformations as a function of time. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both gated SPECT and 4D echocardiography.

RESULTS

The results obtained showed a good correlation between volumes measured with the two modalities, but a slight overestimation of volumes with gated SPECT. The influence of filtering and pixel size parameters on the measured volumes was quantified for gated SPECT, in order to correct the overestimation.

CONCLUSION

The agreement between gated SPECT (after correction) and 4D echocardiography confirmed the relevance of the comparisons. This study was an initial step before conducting clinical trials to compare exhaustively left ventricular volumes obtained with the two modalities.

Effects of loop diuretics on myocardial fibrosis and collagen type I turnover in chronic heart failure

OBJECTIVES

This individually randomized, open-label, parallel-group pilot study was designed to test the hypothesis that the ability of loop diuretics to interfere with cardiac fibrosis in chronic heart failure (CHF) may be different between compounds.

BACKGROUND

The apparent mortality and cardiac benefits seen in studies comparing torasemide with furosemide in CHF suggest that torasemide may have beneficial effects beyond diuresis (e.g., on the process of cardiac fibrosis).

METHODS

Patients with New York Heart Association functional class II to IV CHF received diuretic therapy with either 10 to 20 mg/day oral torasemide (n = 19) or 20 to 40 mg/day oral furosemide (n = 17), in addition to their existing standard CHF therapy for eight months. At baseline and after eight months, right septal endomyocardial biopsies were obtained to quantify collagen volume fraction (CVF) with an automated image analysis system. Serum carboxy-terminal peptide of procollagen type I (PIP) and serum carboxy-terminal telopeptide of collagen type I (CITP), indexes of collagen type I synthesis and degradation, respectively, were measured by specific radioimmunoassays.

RESULTS

In torasemide-treated patients, CVF decreased from 7.96 +/- 0.54% to 4.48 +/- 0.26% (p < 0.01), and PIP decreased from 143 +/- 7 to 111 +/- 3 microg/l (p < 0.01). Neither CVF nor PIP changed significantly in furosemide-treated patients. In all patients, CVF was directly correlated with PIP (r = 0.88, p < 0.001) before and after treatment. No changes in CITP were observed with treatment in either group.

CONCLUSIONS

These findings suggest that loop diuretics possess different abilities to reverse myocardial fibrosis and reduce collagen type I synthesis in patients with CHF.

Single photon emission computed tomography radionuclide ventriculography in the noninvasive diagnosis and evaluation of a false left ventricular aneurysm (pseudoaneurysm)

An inferior wall false aneurysm (pseudoaneurysm) was diagnosed in a 77-year-old male by single photon emission computed tomography (SPECT) radionuclide ventriculography (RNV). This immediately followed routine planar RNV because the latter did not lead to definitive characterization of the type of aneurysm and did not ideally characterize the location and size of the aneurysm. RNV was followed by false-negative first-pass radionuclide ventriculography, routine echocardiography, and gated magnetic resonance imaging of the heart (cardiac MRI). A definitive diagnosis of a false aneurysm is found at surgery and pathology; however, the patient declined surgery and has done well for 1.5 years after these imaging studies. The first-pass study is limited with relatively small pseudoaneurysms, like in this case. Echocardiography is noninvasive and can show wall motion and aneurysm size. Cardiac MRI is the most expensive noninvasive study but, in addition to revealing the diameters of the neck and body of the aneurysm, MRI is able to characterize the surrounding myocardium. This case report suggests the critical information needed for a confident, noninvasive diagnosis of false aneurysm can be obtained with SPECT RNV. The location of the aneurysm is easily determined, and the relative diameters of the neck to the body of the aneurysm can be easily seen. SPECT RNV is superior to planar RNV and first-pass radionuclide ventriculography in making a diagnosis of false aneurysm. Although RNV might be unable to directly demonstrate the perfusion and thickness of the myocardium, it has an advantage over MRI in terms of ejection fraction (EF) and cost.

Validation of a volumic reconstruction in 4-d echocardiography and gated SPECT using a dynamic cardiac phantom

A dynamic cardiac phantom was used as a reference to compare the volumes reconstructed with 4-D echocardiography and gated single-photon emission computed tomography (SPECT). 4-D echocardiography used a new prototype of rotating scan head to acquire ultrasound (US) images during a cardiac cycle, associated with a new protocol (left ventricular 4-D or LV 4-D) to reconstruct the volume deformations of the heart as a function of time. Gated SPECT data were acquired with a standard single-head gamma camera, and the reconstructions were carried out using the Mirage software released by Segami. The influences of different LV 4-D parameters were tested and analyzed. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both LV 4-D and gated SPECT. Results obtained showed a straight correlation between the two examinations. The agreement confirmed the relevance of the comparisons. This study is an initial step before conducting clinical trials to exhaustively compare the two modalities.