Evaluation of left ventricular endocardial volumes and ejection fractions computed from gated perfusion SPECT with magnetic resonance imaging: comparison of two methods.

BACKGROUND: Two methods of computing left ventricular volumes and ejection fraction (EF) from 8-frame gated perfusion single photon emission computed tomography (SPECT) were compared with each other and with magnetic resonance (MR) imaging. METHODS AND RESULTS: Thirty-five subjects underwent 8-frame gated dual-isotope SPECT imaging and 12- to 16-frame gated MR imaging. Endocardial boundaries on short-axis MR images were hand traced by experts blinded to any SPECT results. Volumes and EF were computed with the use of Simpson's rule. SPECT images were analyzed for the same functional variables with the use of 2 automatic programs, Quantitative Gated SPECT (QGS) and the Emory Cardiac Toolbox (ECTb). The mean difference between MR and SPECT EF was 0.008 for ECTb and 0.08 for QGS. QGS showed a slight trend toward higher correlation for EF (r = 0.72, SE of the estimate = 0.08) than ECTb (r = 0.70, SE of the estimate = 0.09). For both SPECT methods, left ventricular volumes were similarly correlated with MR, although SPECT volumes were higher than MR values by approximately 30%. CONCLUSIONS: QGS and ECTb values of cardiac function computed from 8-frame gated perfusion SPECT correlate very well with each other and correlate well with MR. Averaged over all subjects, ECTb measurements of EF are not significantly different from MR values but QGS significantly underestimates the MR values.

Therapeutic angiogenesis with recombinant fibroblast growth factor-2 improves stress and rest myocardial perfusion abnormalities in patients with severe symptomatic chronic coronary artery disease.

BACKGROUND: We report the effects of the administration of recombinant fibroblast growth factor-2 (rFGF-2) protein on myocardial perfusion using single photon emission computed tomography imaging in humans with advanced coronary disease. METHODS AND RESULTS: A total of 59 patients with coronary disease that was not amenable to mechanical revascularization underwent intracoronary (n=45) or intravenous (n=14) administration of rFGF-2 in ascending doses. Changes in perfusion were evaluated at baseline and again at 29, 57, and 180 days after rFGF-2 administration. In this uncontrolled study, perfusion scans were analyzed by 2 observers who were blinded to patient identity and test sequence; scans were displayed in random order, with scans from nonstudy patients randomly interspersed to enhance blinding. Combining all dose groups, a reduction occurred in the per-segment reversibility score (reflecting the magnitude of inducible ischemia) from 1.7+/-0.4 at baseline to 1.1+/-0.6 at day 29 (P:<0.001), 1.2+/-0.7 at day 57 (P:<0.001), and 1.1+/-0.7 at day 180 (P:<0.001). The 37 patients with evidence of resting hypoperfusion had evidence of improved resting perfusion: their per-segment rest perfusion score of 1.5+/-0. 5 at baseline decreased to 1.0+/-0.8 at day 29 (P:<0.001), 1.0+/-0.8 at day 57 (P:=0.003), and 1.1+/-0.9 at day 180 (P:=0.11). CONCLUSIONS: These preliminary data suggest that the administration of rFGF-2 to patients with advanced coronary disease resulted in an attenuation of stress-induced ischemia and an improvement in resting myocardial perfusion; these findings are consistent with a favorable effect of therapeutic angiogenesis.

Two-point, timesaving method for measurement of gastric emptying with diagnostic accuracy comparable to that of the conventional method.

Solid-phase gastric emptying is linear. Therefore, the authors calculated gastric-emptying half-time, the time for half of the ingested solids or liquids to leave the stomach, with the conventional multiple-point method and the proposed two-point method (at 0 and 120 minutes) in retrospective and prospective studies of 50 patients each. The results showed excellent correlation. Results with the two-point method were comparable to those with the multiple-point method, and the two-point method substantially reduced technologist and camera times.

Attenuation and scatter compensation in myocardial perfusion SPECT.

Nonuniform attenuation, Compton scatter, and limited, spatially varying resolution degrade both the qualitative and quantitative nature of myocardial perfusion SPECT. Physicians must recognize and understand the effects of these factors on myocardial perfusion SPECT for optimal interpretation and use of this important imaging technique. Recent developments in the design and implementation of compensation algorithms and transmission-based imaging promise to provide clinically realistic solutions to these effects and provide the framework for truly quantitative imaging. This achievement should improve the diagnostic accuracy and cost-effectiveness of myocardial perfusion SPECT.

In-111 labeled octreotide imaging of a primary carcinoid lesion undetected by conventional imaging studies in a patient with "chronic pancreatitis".

This is a case report of a patient with an initial diagnosis of chronic pancreatitis who actually had metastatic carcinoid tumor. His symptoms of abdominal pain, weight loss, and diarrhea were manifestations of the large tumor bulk within the liver as well as carcinoid syndrome. Although abdominal CT scans showed multiple liver lesions, the primary lesion was not identified by conventional imaging studies. However, the mid-gut primary lesion was visualized on in-111 labeled octreotide scintigraphy; where the liver lesions were better delineated and seen to be separate from the normal pancreas when the Tc-99m sulfur colloid images were compared to the octreotide images.

SPECT quantification: a simplified method of attenuation and scatter correction for cardiac imaging.

The quantitative and visual interpretation of SPECT myocardial perfusion images is limited by physical factors such as photon attenuation, Compton scatter, and finite resolution effects. A method of attenuation correction is described for use in nonhomogeneous media and applied to cardiac SPECT imaging. This method, termed multiplicative variable attenuation compensation (MVAC), uses tissue contours determined from segmentation of a transmission scan to assign a priori determined attenuation coefficients to different tissue regions of the transaxial images. An attenuation correction map is then constructed using a technique inspired by Chang's method that includes regionally dependent attenuation within the chest cavity and is applied after reconstruction by filtered backprojection. Scatter correction using the subtraction of a simultaneously acquired scatter window image enables the use of narrow beam attenuation coefficients. Experimental measurements to evaluate these methods were conducted for 201Tl and 99mTc SPECT using a homomorphic cardiac phantom. Finite resolution effects were included in the evaluation of results by computer simulation of the three-dimensional activity distribution. The correction methodology was shown to substantially improve both relative and absolute quantification of uniform and nonuniform regions of activity in the phantom's myocardial wall.

Effects of myocardial wall thickness on SPECT quantification.

The effects of changing myocardial wall thickness in single photon emission computed tomography (SPECT) imaging are characterized, and a method which may be used to compensate for these effects is presented. The underlying principle is that the phenomena of attenuation, Compton scatter, and finite resolution can be separated and treated independently. Only finite resolution and its effects, along with a proposed method for correcting these effects, are addressed. A cardiac phantom with varying wall thickness (9-23 mm) was developed to characterize the dependence effects on (201)Tl myocardial SPECT images. Correction factors in the form of recovery coefficients have been developed with the use of a convolution simulation, and are shown to improve substantially the agreement of counts extracted from SPECT images of the phantom with the actual (201)Tl concentration. The degree of improvement, however, is markedly affected by external attenuation. Clinical application of this method will require corrections for attenuation and scatter or the development of regional recovery coefficients which include these effects.