Faculty Bibliography

BACKGROUND: Various algorithms have been developed to compute right ventricular (RV) and left ventricular (LV) end-diastolic volumes, end-systolic volumes, and ejection fractions (EF) from tomographic radionuclide ventriculography (TRV). The aims of this investigation were to establish sex-specific normal limits, to determine whether different algorithms produce the same normal values, and to compare TRV normal limits vs for magnetic resonance imaging values in the literature. METHODS: Fifty-one healthy volunteers (29 men, 22 women) were studied prospectively. All subjects had normal electrocardiograms and echocardiographic examinations, and underwent both planar radionuclide ventriculography and TRV. Four algorithms were used to process TRV data. RESULTS: Normal limits for most functional parameters differed significantly from one algorithm to another. Volumes were greater in men, but no statistically significant differences were found between men and women for LV EF or RV EF values for any method. Normal LV and RV EF and volumes were largely consistent with the literature for cardiac magnetic resonance imaging. CONCLUSIONS: Ventricular measurements differ significantly among TRV algorithms. Therefore, it is important to apply sex-specific normal limits that are specific to a given TRV algorithm in interpreting LV and RV EF and volume measurements for each patient.

The imaging sequences used in first pass (FP) perfusion to date have important limitations in contrast-to-noise ratio (CNR), temporal and spatial resolution, and myocardial coverage. As a result, controversy exists about optimal imaging strategies for FP myocardial perfusion. Since imaging performance varies from subject to subject, it is difficult to form conclusions without direct comparison of different sequences in the same subject. The purpose of this study was to directly compare the saturation recovery SSFP technique to other more commonly used myocardial first pass perfusion techniques, namely spoiled GRE and segmented EPI. Differences in signal-to-noise ratio (SNR), CNR, relative maximal upslope (RMU) of signal amplitude, and artifacts at comparable temporal and spatial resolution among the three sequences were investigated in computer simulation, contrast agent doped phantoms, and 16 volunteers. The results demonstrate that SSFP perfusion images exhibit an improvement of approximately 77% in SNR and 23% in CNR over spoiled GRE and 85% SNR and 50% CNR over segmented EPI. Mean RMU was similar between SSFP and spoiled GRE, but there was a 58% increase in RMU with SSFP versus segmented EPI.

PURPOSE: To study a first-pass myocardial perfusion imaging method, such that long-axis imaging slices are obtained rotationally around the short-axis centroid of the left ventricular cavity, in order to improve myocardial coverage and better delineate the basal and apical myocardium. MATERIALS AND METHODS: This rotational long-axis (RLA) method was examined in 12 volunteers and compared to the perfusion images from conventional parallel short-axis (PSA) acquisitions in terms of the contrast to noise ratio (CNR), relative signal upslope and myocardial coverage. Both RLA and PSA first-pass perfusion images were acquired on each volunteer with otherwise identical imaging parameters using the partial Fourier saturation recovery steady state gradient echo sequence with refocused magnetization (TrueFISP) technique. RESULTS: Compared to PSA, RLA perfusion images with identical imaging parameters on the same subject exhibit an average of near 30% improvement in total myocardial area imaged. In addition, true basal and apical myocardium was seen on RLA, but not on PSA. The mean CNR and relative upslope were similar between the two techniques. CONCLUSIONS: This RLA perfusion imaging scheme is superior to the conventional PSA approach in terms of extent myocardial coverage and delineation of basal and apical regions of the left ventricle.

BACKGROUND: We compared gated blood pool single photon emission computed tomography (SPECT) (GBPS), planar gated blood pool imaging (planar GBP), and cardiac magnetic resonance (CMR) measurements of left ventricular (LV) end-diastolic volume (EDV) and ejection fraction (EF) in patients with abnormal left ventricles. METHODS AND RESULTS: LV functional parameters were measured for 40 subjects (age, 59 +/- 13 years; 85% male) by GBPS, planar GBP, and CMR. GBPS data were analyzed by use of count-threshold software (BP-SPECT) and surface gradient software (QBS). Limits of agreement with CMR for EF were -5% to +18%, -15% to +14%, and -15% to +16% for BP-SPECT, QBS, and planar GBP, respectively. However, limits of agreement with CMR for LV EDV were wide by both GBPS methods: -118 mL to +55 mL and -143 mL to +22 mL for BP-SPECT and QBS, respectively. Bland-Altman reproducibility limits for EF were -9% to +8%, -6% to +9%, and -7% to +7% by BP-SPECT, QBS, and planar GBP, respectively, and those for EDV were -46 mL to +48 mL and -31 mL to +35 mL by BP-SPECT and QBS, respectively. CONCLUSION: GBPS LV EF measurements agree with measurements by CMR and are as reproducible as planar GBP measurements. However, wide limits of agreement of radionuclide versus CMR values suggest that caution must be applied in interpreting GBPS LV volume results, especially for patients with markedly abnormal left ventricles.

BACKGROUND: Calculation differences between various gated blood pool (GBP) single photon emission computed tomography (SPECT) (GBPS) algorithms may arise as a result of different modeling assumptions. Little information has been available thus far regarding differences for right ventricular (RV) function calculations, for which GBPS may be uniquely well suited. METHODS AND RESULTS: Measurements of QBS (Cedars-Sinai Medical Center, Los Angeles, Calif) and BP-SPECT (Columbia University, New York, NY) algorithms were evaluated. QBS and BP-SPECT left ventricular (LV) ejection fraction (EF) correlated strongly with conventional planar-GBP LVEF for 422 patients (r = 0.81 vs r = 0.83). QBS correlated significantly more strongly with BP-SPECT for LVEF than for RVEF (r = 0.80 vs r = 0.41). Both algorithms demonstrated significant gender differences for 31 normal subjects. BP-SPECT normal LVEF (67% +/- 9%) was significantly closer to values in the magnetic resonance imaging (MRI) literature (68% +/- 5%) than QBS (58% +/- 9%), but both algorithms underestimated normal RVEF (52% +/- 7% and 50% +/- 9%) compared with the MRI literature (64% +/- 9%). For 21 patients, QBS correlated similarly to MRI as BP-SPECT for LVEF (r = 0.80 vs r = 0.85) but RVEF correlation was significantly weaker (r = 0.47 vs r = 0.81). For 16 dynamic phantom simulations, QBS LVEF correlated similarly to BP-SPECT (r = 0.81 vs r = 0.91) but QBS RVEF correlation was significantly weaker (r = 0.62 vs r = 0.82). Volumes were lower by QBS than BP-SPECT for all data types. CONCLUSIONS: Both algorithms produced LV parameters that correlated strongly with all forms of image data, but all QBS RV relationships were significantly different from BP-SPECT RV relationships. Differences between the two algorithms were attributed to differences in their underlying ventricular modeling assumptions.