Analytic Validation of the Automated Bone Scan Index as an Imaging Biomarker to Standardize Quantitative Changes in Bone Scans of Patients with Metastatic Prostate Cancer.

UNLABELLED: A reproducible and quantitative imaging biomarker is needed to standardize the evaluation of changes in bone scans of prostate cancer patients with skeletal metastasis. We performed a series of analytic validation studies to evaluate the performance of the automated bone scan index (BSI) as an imaging biomarker in patients with metastatic prostate cancer. METHODS: Three separate analytic studies were performed to evaluate the accuracy, precision, and reproducibility of the automated BSI. Simulation study: bone scan simulations with predefined tumor burdens were created to assess accuracy and precision. Fifty bone scans were simulated with a tumor burden ranging from low to high disease confluence (0.10-13.0 BSI). A second group of 50 scans was divided into 5 subgroups, each containing 10 simulated bone scans, corresponding to BSI values of 0.5, 1.0, 3.0, 5.0, and 10.0. Repeat bone scan study: to assess the reproducibility in a routine clinical setting, 2 repeat bone scans were obtained from metastatic prostate cancer patients after a single 600-MBq (99m)Tc-methylene diphosphonate injection. Follow-up bone scan study: 2 follow-up bone scans of metastatic prostate cancer patients were analyzed to determine the interobserver variability between the automated BSIs and the visual interpretations in assessing changes. The automated BSI was generated using the upgraded EXINI bone(BSI) software (version 2). The results were evaluated using linear regression, Pearson correlation, Cohen κ measurement, coefficient of variation, and SD. RESULTS: Linearity of the automated BSI interpretations in the range of 0.10-13.0 was confirmed, and Pearson correlation was observed at 0.995 (n = 50; 95% confidence interval, 0.99-0.99; P < 0.0001). The mean coefficient of variation was less than 20%. The mean BSI difference between the 2 repeat bone scans of 35 patients was 0.05 (SD = 0.15), with an upper confidence limit of 0.30. The interobserver agreement in the automated BSI interpretations was more consistent (κ = 0.96, P < 0.0001) than the qualitative visual assessment of the changes (κ = 0.70, P < 0.0001) was in the bone scans of 173 patients. CONCLUSION: The automated BSI provides a consistent imaging biomarker capable of standardizing quantitative changes in the bone scans of patients with metastatic prostate cancer.

Area of ischemia assessed by physicians and software packages from myocardial perfusion scintigrams.

BACKGROUND: The European Society of Cardiology recommends that patients with >10% area of ischemia should receive revascularization. We investigated inter-observer variability for the extent of ischemic defects reported by different physicians and by different software tools, and if inter-observer variability was reduced when the physicians were provided with a computerized suggestion of the defects. METHODS: Twenty-five myocardial perfusion single photon emission computed tomography (SPECT) patients who were regarded as ischemic according to the final report were included. Eleven physicians in nuclear medicine delineated the extent of the ischemic defects. After at least two weeks, they delineated the defects again, and were this time provided a suggestion of the defect delineation by EXINI HeartTM (EXINI). Summed difference scores and ischemic extent values were obtained from four software programs. RESULTS: The median extent values obtained from the 11 physicians varied between 8% and 34%, and between 9% and 16% for the software programs. For all 25 patients, mean extent obtained from EXINI was 17.0% (± standard deviation (SD) 14.6%). Mean extent for physicians was 22.6% (± 15.6%) for the first delineation and 19.1% (± 14.9%) for the evaluation where they were provided computerized suggestion. Intra-class correlation (ICC) increased from 0.56 (95% confidence interval (CI) 0.41-0.72) to 0.81 (95% CI 0.71-0.90) between the first and the second delineation, and SD between physicians were 7.8 (first) and 5.9 (second delineation). CONCLUSIONS: There was large variability in the estimated ischemic defect size obtained both from different physicians and from different software packages. When the physicians were provided with a suggested delineation, the inter-observer variability decreased significantly.

Computer-aided diagnosis system outperforms scoring analysis in myocardial perfusion imaging.

BACKGROUND: The aim of this myocardial perfusion imaging (MPI) study was to compare the diagnostic performance of two computer-aided diagnosis (CAD) systems, EXINI Heart(TM) (EXINI), and PERFEX(TM) (PERFEX) Emory Cardiac Toolbox (ECT), and the summed stress score (SSS) values from both software packages. METHODS: We studied 1,052 consecutive patients who underwent 2-day stress/rest (99m)Tc-sestamibi MPI studies. The reference standard classifications for the MPI studies were obtained from three experienced physicians who separately classified all cases regarding the presence or absence of ischemia and/or infarction. Automatic processing was carried out using EXINI and PERFEX to obtain CAD results and SSS values based on the 17-segment model. RESULTS: The three experts' classifications showed ischemia in 257 patients and abnormal studies, i.e., either ischemia or infarction or both, in 318 patients. Accuracy was significantly higher in EXINI than in PERFEX, regarding both the detection of ischemia (87.4 vs 77.6%; P < 0.0001) and the detection of abnormal studies (91.6 vs 67.9%; P < 0.0001). EXINI's CAD system showed a higher specificity than its SSS values (86.8 vs 73.6%; P < 0.0001) at the same level of sensitivity. CONCLUSIONS: EXINI demonstrated greater diagnostic accuracy for detection of ischemia and abnormal studies than did PERFEX. EXINI CAD also outperformed its SSS analysis.

Progression of bone metastases in patients with prostate cancer - automated detection of new lesions and calculation of bone scan index.

BACKGROUND: The objective of this study was firstly to develop and evaluate an automated method for the detection of new lesions and changes in bone scan index (BSI) in serial bone scans and secondly to evaluate the prognostic value of the method in a group of patients receiving chemotherapy. METHODS: The automated method for detection of new lesions was evaluated in a group of 266 patients using the classifications by three experienced bone scan readers as a gold standard. The prognostic value of the method was assessed in a group of 31 metastatic hormone-refractory prostate cancer patients who were receiving docetaxel. Cox proportional hazards were used to investigate the association between percentage change in BSI, number of new lesions and overall survival. Kaplan-Meier estimates of the survival function were used to indicate a significant difference between patients with an increase/decrease in BSI or those with two or more new lesions or less than two new lesions. RESULTS: The automated method detected progression defined as two or more new lesions with a sensitivity of 93% and a specificity of 87%. In the treatment group, both BSI changes and the number of new metastases were significantly associated with survival. Two-year survival for patients with increasing and decreasing BSI from baseline to follow-up scans were 18% and 57% (p = 0.03), respectively. Two-year survival for patients fulfilling and not fulfilling the criterion of two or more new lesions was 35% and 38% (n.s.), respectively. CONCLUSIONS: An automated method can be used to calculate the number of new lesions and changes in BSI in serial bone scans. These imaging biomarkers contained prognostic information in a small group of patients with prostate cancer receiving chemotherapy.

Right ventricular ejection fraction during exercise as a predictor of mortality in patients awaiting lung transplantation: a cohort study.

OBJECTIVE: The occurrence of right ventricular dysfunction is a well-known indicator of poor prognosis in patients with chronic cardiopulmonary disease. The role of right ventricular ejection fraction (RVEF) at rest and during exercise as predictors of outcome in patients awaiting lung transplantation (LTx) is unclear. DESIGN: We performed a retrospective analysis of lung transplant candidates who had undergone equilibrium radionuclide angiography (ERNA), to determine baseline and exercise RVEF. Lung function, gas exchange and pulmonary haemodynamics were also assessed. PATIENTS AND MAIN OUTCOME MEASURES: 152 patients (mean age 47±11 years; 59% women) were included in the study. Primary endpoint was death on the waiting list for LTx. Main diagnoses were α-1 antitrypsin deficiency (n=35), chronic obstructive pulmonary disease (n=41), cystic fibrosis (n=10), interstitial lung disease (n=34) and pulmonary arterial hypertension (n=32). Twenty-five patients died (16, 4%). LTx was performed in 121 patients. The mean RVEF at rest was equal to mean RVEF during exercise (38±12%). In univariate analysis RVEF at rest, RVEF during exercise, heart rate and forced volume capacity (FVC) % of predicted were factors significantly associated with risk of death. In multivariate analysis RVEF during exercise and FVC% of predicted were independent predictors of death. CONCLUSIONS: In lung transplant candidates, right ventricular function during exercise is a stronger predictor of outcome than right ventricular function at rest. RVEF during exercise assessed by ERNA could be incorporated into priority-based allocation algorithms for LTx.

When is reacquisition necessary due to high extra-cardiac uptake in myocardial perfusion scintigraphy?

BACKGROUND: Technetium-labeled agents, which are most often used for assessing myocardial perfusion in myocardial perfusion scintigraphy (MPS), are cleared by the liver and excreted by the biliary system. Spillover from extra-cardiac activity into the myocardium, especially the inferior wall, might conceal defects and lower the diagnostic accuracy of the study. The objective was to determine rules of thumb for when reacquisition is useful due to high extra-cardiac uptake, i.e., when interpretation of the studies was affected by poor image quality. METHODS: Patients admitted to MPS at any of the three study sites, who also underwent a reacquisition due to high extra-cardiac uptake were included. Image quality was assessed by ten technologists on a scale ranging from 1 to 5. Interpretations regarding the presence/absence of ischemia/infarction, including the certainty of the diagnosis, were made by three physicians. RESULTS: There was a statistically significant increase in image quality between the first and the repeated acquisition (1,256 cases of increased quality at the repeated study (66%), 134 cases of decreased quality at the repeated study (7%), 510 cases of unchanged quality (27%) P < 0.0001). The number of equivocal studies, interpreted by physicians, decreased when evaluating the repeated studies compared to the first studies for all physicians, both for the interpretations of ischemia and for infarction. Receiver operating characteristic analyses revealed that for both endpoints (ischemia, infarction) and all physicians, the optimal cutoff point for performing a reacquisition was between quality categories 2 and 3. CONCLUSION: This study indicates that repeat acquisition is useful when (1) the intensity of the extra-cardiac uptake is equal to or higher than the cardiac uptake when there is no separation between the extra-cardiac uptake and the inferior cardiac wall and (2) when the intensity of the extra-cardiac uptake is higher than the cardiac uptake when there is a separation between the extra-cardiac uptake and the inferior wall of less than one cardiac wall.

Bone Scan Index: a prognostic imaging biomarker for high-risk prostate cancer patients receiving primary hormonal therapy.

BACKGROUND: The objective of this study was to explore the prognostic value of the Bone Scan Index (BSI) obtained at the time of diagnosis in a group of high-risk prostate cancer patients receiving primary hormonal therapy. METHODS: This was a retrospective study based on 130 consecutive prostate cancer patients at high risk, based on clinical stage (T2c/T3/T4), Gleason score (8 to 10) and prostate-specific antigen (PSA) (> 20 ng/mL), who had undergone whole-body bone scans < 3 months after diagnosis and who received primary hormonal therapy. BSI was calculated using an automated method. Cox proportional-hazards regression models were used to investigate the association between clinical stage, Gleason score, PSA, BSI and survival. Discrimination between prognostic models was assessed using the concordance index (C-index). RESULTS: In a multivariate analysis, Gleason score (p = 0.01) and BSI (p < 0.001) were associated with survival, but clinical stage (p = 0.29) and PSA (p = 0.57) were not prognostic. The C-index increased from 0.66 to 0.71 when adding BSI to a model including clinical stage, Gleason score and PSA. The 5-year probability of survival was 55% for patients without metastases, 42% for patients with BSI < 1, 31% for patients with BSI = 1 to 5, and 0% for patients with BSI > 5. CONCLUSIONS: BSI can be used as a complement to PSA to risk-stratify high-risk prostate cancer patients at the time of diagnosis. This imaging biomarker, reflecting the extent of metastatic disease, can be of value both in clinical trials and in patient management when deciding on treatment.

A novel automated platform for quantifying the extent of skeletal tumour involvement in prostate cancer patients using the Bone Scan Index.

BACKGROUND: There is little consensus on a standard approach to analysing bone scan images. The Bone Scan Index (BSI) is predictive of survival in patients with progressive prostate cancer (PCa), but the popularity of this metric is hampered by the tedium of the manual calculation. OBJECTIVE: Develop a fully automated method of quantifying the BSI and determining the clinical value of automated BSI measurements beyond conventional clinical and pathologic features. DESIGN, SETTING, AND PARTICIPANTS: We conditioned a computer-assisted diagnosis system identifying metastatic lesions on a bone scan to automatically compute BSI measurements. A training group of 795 bone scans was used in the conditioning process. Independent validation of the method used bone scans obtained ≤3 mo from diagnosis of 384 PCa cases in two large population-based cohorts. An experienced analyser (blinded to case identity, prior BSI, and outcome) scored the BSI measurements twice. We measured prediction of outcome using pretreatment Gleason score, clinical stage, and prostate-specific antigen with models that also incorporated either manual or automated BSI measurements. MEASUREMENTS: The agreement between methods was evaluated using Pearson's correlation coefficient. Discrimination between prognostic models was assessed using the concordance index (C-index). RESULTS AND LIMITATIONS: Manual and automated BSI measurements were strongly correlated (ρ=0.80), correlated more closely (ρ=0.93) when excluding cases with BSI scores≥10 (1.8%), and were independently associated with PCa death (p<0.0001 for each) when added to the prediction model. Predictive accuracy of the base model (C-index: 0.768; 95% confidence interval [CI], 0.702-0.837) increased to 0.794 (95% CI, 0.727-0.860) by adding manual BSI scoring, and increased to 0.825 (95% CI, 0.754-0.881) by adding automated BSI scoring to the base model. CONCLUSIONS: Automated BSI scoring, with its 100% reproducibility, reduces turnaround time, eliminates operator-dependent subjectivity, and provides important clinical information comparable to that of manual BSI scoring.

Carotid artery longitudinal displacement predicts 1-year cardiovascular outcome in patients with suspected coronary artery disease.

OBJECTIVE: Total longitudinal displacement (tLoD) of the common carotid artery can be measured using the ultrasound-based velocity vector imaging (VVI) technique. This study aimed to investigate clinical correlates and the possible predictive value of tLoD for cardiovascular outcome. METHODS AND RESULTS: Four hundred forty-one patients referred for myocardial perfusion scintigraphy examination for suspected coronary artery disease were recruited and underwent VVI-assisted tLoD measurement. Patients were followed up with regard to major adverse cardiovascular event (MACE) 1 year later. Low tLoD (≤ 0.055 mm) was associated with greater clinically determined myocardial ischemia (P<0.01). During a median follow-up time of 372 days, 61 MACEs occurred. In a Kaplan-Meier survival analysis, high tLoD (>0.055 mm) predicted 1-year event-free survival (P<0.01, highest versus lowest tertile odds ratio [OR] = 1.9). In a Cox regression model adjusting for age, gender, intima-media thickness, radial strain, pulse pressure, and percentage reversibility mass of myocardium, low tLoD remained a significant independent predictor of MACE (P = 0.03). Finally, low tLoD provided additional predictive value in subjects with increased intima-media thickness. CONCLUSIONS: VVI-derived tLoD seems to reflect cardiovascular status and predicts short-term event-free survival in medium- to high-risk patients. Finally, tLoD per se or in combination with intima-media thickness measurement may be a novel cardiovascular surrogate biomarker.

Clinical data do not improve artificial neural network interpretation of myocardial perfusion scintigraphy.

Artificial neural networks interpretation of myocardial perfusion scintigraphy (MPS) has so far been based on image data alone. Physicians reporting MPS often combine image and clinical data. The aim was to evaluate whether neural network interpretation would be improved by adding clinical data to image data. Four hundred and eighteen patients were used for training and 532 patients for testing the neural networks. First, the network was trained with image data alone and thereafter with image data in combination with clinical parameters (age, gender, previous infarction, percutaneous coronary intervention, coronary artery bypass grafting, typical chest pain, present smoker, hypertension, hyperlipidaemia, diabetes, peripheral vascular disease and positive family history). Expert interpretation was used as gold standard. Receiver operating characteristic (ROC) curves were calculated, and the ROC areas for the networks trained with and without clinical data were compared for the diagnosis of myocardial infarction and ischaemia. There was no statistically significant difference in ROC area for the diagnosis of myocardial infarction between the neural network trained with the combination of clinical and image data (95.8%) and with image data alone (95.2%). For the diagnosis of ischaemia, there was no statistically significant difference in ROC area between the neural network trained with the combination of clinical and image data (87.9%) and with image data alone (88.0%). Neural network interpretation of MPS is not improved when clinical data are added to perfusion and functional data. One reason for this could be that experts base their interpretations of MPS mainly on the images and to a lesser degree on clinical data.

Relation between pain and skeletal metastasis in patients with prostate or breast cancer.

The aim of this study was to examine the relation between pain and bone metastases in a group of patients with prostate or breast cancer that had been referred for bone scintigraphy. Whole-body bone scans, anterior and posterior views obtained with a dual detector gamma camera were studied from 101 consecutive patients who had undergone scintigraphy (600 MBq Tc-99m MDP) because of suspected bone metastatic disease. At the time of the examination, all patients were asked whether they felt any pain or had recently a trauma. This information was correlated with the classifications regarding the presence or absence of bone metastases made by a group of three experienced physicians. In patients with prostate cancer, we found metastases in 47% (18/38) of the patients with pain, but only in 12% (2/17) of the patients without pain (p = 0.01). In patients with breast cancer, on the other hand, metastases were more common in patients without pain (71%; 10/14) than in patients with pain (34%; 11/32) (p = 0.02). In conclusion, a significant relation between pain and skeletal metastases could be found in patients with prostate cancer and a reverse relation in patients with breast cancer.

Diagnostic evaluation of three cardiac software packages using a consecutive group of patients.

PURPOSE: The aim of this study was to compare the diagnostic performance of the three software packages 4DMSPECT (4DM), Emory Cardiac Toolbox (ECTb), and Cedars Quantitative Perfusion SPECT (QPS) for quantification of myocardial perfusion scintigram (MPS) using a large group of consecutive patients. METHODS: We studied 1,052 consecutive patients who underwent 2-day stress/rest 99mTc-sestamibi MPS studies. The reference/gold-standard classifications for the MPS studies were obtained from three physicians, with more than 25 years each of experience in nuclear cardiology, who re-evaluated all MPS images. Automatic processing was carried out using 4DM, ECTb, and QPS software packages. Total stress defect extent (TDE) and summed stress score (SSS) based on a 17-segment model were obtained from the software packages. Receiver-operating characteristic (ROC) analysis was performed. RESULTS: A total of 734 patients were classified as normal and the remaining 318 were classified as having infarction and/or ischemia. The performance of the software packages calculated as the area under the SSS ROC curve were 0.87 for 4DM, 0.80 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.03; other differences p < 0.0001). The area under the TDE ROC curve were 0.87 for 4DM, 0.82 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.0005; other differences p < 0.0001). CONCLUSION: There are considerable differences in performance between the three software packages with 4DM showing the best performance and ECTb the worst. These differences in performance should be taken in consideration when software packages are used in clinical routine or in clinical studies.

Evaluation of new automated gated-SPECT and echocardiographic methods for calculating left ventricular volumes and ejection fraction.

BACKGROUND: Left ventricular (LV) volumes and ejection fraction (LVEF) are assessed using ECG-gated myocardial perfusion scintigraphy (MPS) and echocardiography. We have developed CAFU, a new automated method for the quantification of MPS images. AutoEF software is a new automated method for quantifying echocardiograms (Tomtec research arena). The aim of the study was to compare these new methods with standard methods. METHODS: Patients undergoing clinical MPS were invited to an echocardiographic examination. Eighty-eight patients were included, mean age 64+/-10 years, 50% men. LV volumes and LVEF from the echocardiographic examinations were calculated using the AutoEF software and calculations according to Simpson's rule. The LV volumes and LVEF from the MPS images were calculated using CAFU, Quantitative gated-SPECT (QGS) and Emory Cardiac Toolbox (ECT). RESULTS: The MPS methods revealed larger LV volumes and LVEF compared with the echocardiographic methods. CAFU showed an excellent correlation with QGS and ECT (0.91-0.99). The correlations between the MPS and the echocardiographic methods (0.47-0.88), as well as between the AutoEF-assessed values and Simpson's method (0.57-0.87), were lower, however statistically significant. The correlations between the methods were higher for LV volumes than for LVEF. CONCLUSION: There was better agreement between LV volumes and LVEF values from the three MPS methods than between those from the two echocardiographic methods. The echocardiographic methods produced significantly lower LV volumes and LVEF compared with the MPS methods. In the clinical situation, LV volumes and LVEF values from different types of examination or different software packages should be treated with caution.

Can nuclear medicine technologists assess whether a myocardial perfusion rest study is required?

UNLABELLED: Both stress and rest imaging are usually performed to diagnose ischemia or infarction in the left ventricle. If the stress study is performed first and the images indicate normal findings, it might be unnecessary to perform the rest study. The current study determines whether nuclear medicine technologists can assess the necessity of a rest study. METHODS: The results of gated SPECT performed using a 2-d nongated stress and gated rest (99m)Tc-sestamibi protocol for 532 consecutive patients were studied. Myocardial perfusion imaging was performed for diagnosing coronary artery disease (CAD) in 421 patients and for managing known CAD in 107 patients; 4 patients were examined for other reasons. Seventy-nine patients had previous myocardial infarction. Visual interpretation by 1 experienced physician at the time of clinical reporting was used as the gold standard for determining the scintigraphic presence of myocardial infarction or ischemia; rest, stress, and gated rest images and clinical information were available to this physician. All cases categorized as infarction or ischemia present or probably present were categorized as the group requiring a rest study (i.e., the "rest-study-required group"), whereas all other cases were categorized as the group not requiring a rest study (i.e., the "no-rest-study-required group"). A total of 3 physicians and 3 technologists independently interpreted the nongated stress images (slice images and polar plots) and decided whether a rest study was required. RESULTS: In the rest-study-required group, the 3 technologists correctly classified on average 171 of the 172 cases, and the 3 physicians correctly classified 169 (a difference that was not statistically significant). In the no-rest-study-required group, the physicians correctly classified 32% and the technologists 21% of the cases (P = 0.001). The risk that a patient sent home without a rest study would have been diagnosed with infarction or ischemia using the combined stress-rest interpretation was 1.3% (1/75) for the technologists and 2.6% (3/115) for the physicians. CONCLUSION: The nuclear medicine technologists were able to assess whether a rest study was needed; the risk that this assessment would be incorrect was not higher for the technologists than it was for the physicians. This type of assessment by a nuclear medicine technologist could be of value in efforts to improve effectiveness at a nuclear medicine clinic.

Evaluation of a decision support system for interpretation of myocardial perfusion gated SPECT.

PURPOSE: We have recently presented a decision support system for interpreting myocardial perfusion scintigraphy (MPS). In this study, we wanted to evaluate the system in a separate hospital from where it was trained and to compare it with a quantification software package. METHODS: A completely automated method based on neural networks was trained for the interpretation of MPS regarding myocardial ischaemia and infarction using 418 MPS from one hospital. Features from each examination describing rest and stress perfusion, regional and global function were used as inputs to different neural networks. After the training session, the system was evaluated using 532 MPS from another hospital. The test images were also processed with the quantification software package Emory Cardiac Toolbox (ECTb). The images were interpreted by experienced clinicians at both the training and the test hospital, regarding the presence or absence of myocardial ischaemia and/or infarction and these interpretations were used as gold standard. RESULTS: The neural network showed a sensitivity of 90% and a specificity of 85% for myocardial ischaemia. The specificity for the ECTb was 46% (p < 0.001), measured at the same sensitivity. The neural network sensitivity for myocardial infarction was 89% and the specificity 96%. The corresponding specificity for the ECTb was 54% (p < 0.001). CONCLUSION: A decision support system based on neural networks presents interpretations more similar to experienced clinicians compared to a conventional automated quantification software package. This study shows the feasibility of disseminating the expertise of experienced clinicians to less experienced physicians by the use of neural networks.

Normal limits for left ventricular ejection fraction and volumes determined by gated single photon emission computed tomography--a comparison between two quantification methods.

To compare gender-related normal limits for left ventricular (LV) ejection fraction (EF), end-diastolic and end-systolic volumes (EDV and ESV), obtained using two myocardial perfusion-gated single photon emission computed tomography (SPECT) quantification methods. A total of 185 patients were retrospectively selected from a consecutive series of patients examined for coronary artery disease (CAD) or for management of known CAD. Patients were included in the study group if they had normal or probably normal results with stress and rest perfusion imaging and if the combined interpretation of perfusion studies and gated rest studies showed no signs or suspicion of myocardial infarction. The gated SPECT studies were performed using a 2-day stress/gated rest Tc-99m sestamibi protocol. All patient studies were processed using CAFU and quantitative-gated SPECT (QGS), the two software packages for quantification of gated SPECT images. The lower normal limits for EF were higher for CAFU compared with QGS for both women (59% versus 53%) and men (54% versus 47%). The upper normal limits for EDV were also higher for CAFU compared with QGS for both women (133 versus 107 ml) and men (182 versus 161 ml). The differences between the software packages were small for ESV (women 44 versus 44 ml; men 69 versus 74 ml). Gender-specific normal limits need to be applied for LV EF and volumes determined by gated SPECT. Separate criteria for abnormal LV EF and EDV need to be used for women and men depending on the software package used.

The added value of ECG-gating for the diagnosis of myocardial infarction using myocardial perfusion scintigraphy and artificial neural networks.

To assess the value of ECG-gating for the diagnosis of myocardial infarction using myocardial perfusion scintigraphy (MPS) and an artificial neural network. A total of 422 patients referred for MPS were studied using a one day (99m)Tc-tetrofosmin protocol. Adenosine stress combined with submaximal dynamic exercise was used. The images were interpreted by one of three experienced clinicians and these interpretations regarding the presence or absence of myocardial infarction were used as the standard. A fully automated method using artificial neural networks was compared with the clinical interpretation. Either perfusion data alone or a combination of perfusion and function from ECG-gated images were used as input to different artificial neural networks. After a training session, the two types of neural networks were evaluated in separate test groups using an eightfold cross-validation procedure. The neural networks trained with both perfusion and ECG-gated images had a 4-7% higher specificity compared with the corresponding networks using perfusion data only, in four of five segments compared at the same level of sensitivity. The greatest improvement in specificity, from 70% to 77%, was seen in the inferior segment. In the septal and lateral segments the specificity rose from 73% to 77% and from 81% to 85%, respectively. In the anterior segment, the increase in specificity from 93% to 94% by adding functional data was not significant. The addition of functional information from ECG-gated MPS is of value for the diagnosis of myocardial infarction using an automated method of interpreting myocardial perfusion images.

Validation of a new automated method for analysis of gated-SPECT images.

We recently presented a new method for quantification of CArdiac FUnction--denoted CAFU--as the first step in the development of an automated method for integrated interpretation of gated myocardial perfusion single photon emission computed tomography (SPECT) images. The aim of this study was to validate CAFU in the assessment of global and regional function of the left ventricle. Quantitative gated-SPECT (QGS), the most widely used software package for quantification of gated-SPECT images, was used as reference method for the measurements of ejection fraction (EF) and ventricular volumes, and visual analysis by an experienced physician was used as reference method for the measurements of regional wall motion and thickening. Two different groups of consecutive patients referred for myocardial perfusion scintigraphy were studied. Global function was evaluated in 316 patients and regional function in 49 other patients. The studies were performed using a 2-day stress/rest 99 m-Tc-sestamibi protocol. A good correlation was found between EF values from QGS and CAFU (EF CAFU = 0.84 EF QGS + 13, r = 0.94), but CAFU values were on average 4 EF points higher than QGS values. With CAFU the segments with normal thickening according to the physician showed significantly higher thickening values (in all parts of the myocardium) compared to the segments classified as having abnormal thickening. In conclusion, this study demonstrates that CAFU can be used to quantify global and regional function in gated-SPECT images. This is an important step in our development of an automated method for integrated interpretation of gated-SPECT myocardial perfusion scintigraphy studies.

A new automated method for analysis of gated-SPECT images based on a three-dimensional heart shaped model.

A new automated method for quantification of left ventricular function from gated-single photon emission computed tomography (SPECT) images has been developed. The method for quantification of cardiac function (CAFU) is based on a heart shaped model and the active shape algorithm. The model contains statistical information of the variability of left ventricular shape. CAFU was adjusted based on the results from the analysis of five simulated gated-SPECT studies with well defined volumes of the left ventricle. The digital phantom NURBS-based Cardiac-Torso (NCAT) and the Monte-Carlo method SIMIND were used to simulate the studies. Finally CAFU was validated on ten rest studies from patients referred for routine stress/rest myocardial perfusion scintigraphy and compared with Cedar-Sinai quantitative gated-SPECT (QGS), a commercially available program for quantification of gated-SPECT images. The maximal differences between the CAFU estimations and the true left ventricular volumes of the digital phantoms were 11 ml for the end-diastolic volume (EDV), 3 ml for the end-systolic volume (ESV) and 3% for the ejection fraction (EF). The largest differences were seen in the smallest heart. In the patient group the EDV calculated using QGS and CAFU showed good agreement for large hearts and higher CAFU values compared with QGS for the smaller hearts. In the larger hearts, ESV was much larger for QGS than for CAFU both in the phantom and patient studies. In the smallest hearts there was good agreement between QGS and CAFU. The findings of this study indicate that our new automated method for quantification of gated-SPECT images can accurately measure left ventricular volumes and EF.