The incremental value of coronary artery calcium score in predicting long-term prognosis and defining the warranty period of normal adenosine stress-only myocardial perfusion imaging using CZT SPECT.

BACKGROUND: Normal stress-only (SO) myocardial perfusion imaging (MPI) using SPECT reduces imaging time and radiation dose with a good prognosis. However, the long-term prognostic value of combining coronary artery calcium score (CACS) with SO MPI to determine the warranty period remains unknown. Hence, we assessed the incremental prognostic value of CACS and its impact on the warranty period of normal SO MPI using SPECT. METHODS: We retrospectively included 1375 symptomatic patients without a history of coronary artery disease (CAD) and a normal SO MPI using adenosine who underwent simultaneous CAC scoring. Annual major adverse cardiac events (MACE) rates were calculated for CACS categories: 0, 1-399, 400-999, and ≥1000. RESULTS: The mean age was 60.0 ± 11.8 years (66.9% female) with a median follow-up of 10.3 [IQR 9.6-10.9] years. The warranty period for annual MACE rate for normal SO SPECT extended the total follow-up time in years. MACE rate categorized by CAC categories demonstrated an increase in MACE rates with increasing CACS; CACS 0 and CACS 1-399 were associated with a 10-year warranty period, CACS 400-999 had a warranty period of 4 years and no warranty period could be given for CACS≥1000 (5.9 % at 1 year). CONCLUSIONS: CACS as an adjunct to normal pharmacological SO MPI provides additional prognostic information and aids in determining a warranty period.

Performance of Digital PET Compared with High-Resolution Conventional PET in Patients with Cancer.

Recently introduced PET systems using silicon photomultipliers with digital readout (dPET) have an improved timing and spatial resolution, aiming at a better image quality than conventional PET (cPET) systems. We prospectively evaluated the performance of a dPET system in patients with cancer, as compared with high-resolution (HR) cPET imaging. Methods: After a single 18F-FDG injection, 66 patients underwent dPET and cPET imaging in randomized order. We used HR reconstructions (2 × 2 × 2 mm voxels) for both scanners and determined SUVmax, SUVmean, lesion-to-background ratio (LBR), metabolic tumor volume (MTV), and lesion diameter in up to 5 18F-FDG-positive lesions per patient. Furthermore, we counted the number of visible and measurable lesions on each PET scan. Two nuclear medicine specialists determined, in a masked manner, the TNM score from both image sets in 30 patients referred for initial staging. For all 66 patients, these specialists separately evaluated image quality (4-point scale) and determined the scan preference. Results: We included 238 lesions that were visible and measurable on both PET scans. For 27 patients, we found 37 additional lesions on dPET (41%) that were unmeasurable (n = 14) or invisible (n = 23) on cPET. Mean (±SD) SUVmean, SUVmax, LBR, and MTV on cPET were 5.2 ± 3.9, 6.9 ± 5.6, 5.0 ± 3.6, and 2,991 ± 13,251 mm3, respectively. On dPET, SUVmean, SUVmax, and LBR increased by 24%, 23%, and 27%, respectively (P < 0.001) whereas MTV decreased by 13% (P < 0.001), compared with cPET. Visual analysis showed TNM upstaging with dPET in 13% of the patients (4/30). dPET images also had higher scores for quality (P = 0.003) and were visually preferred in most cases (65%). Conclusion: dPET improved the detection of small lesions, upstaged the disease, and produced images that were visually preferred to those from HR cPET. More studies are necessary to confirm the superior diagnostic performance of dPET.Keywords: digital PET; conventional PET; FDG PET; lesion detection; cancer imaging.

Does fractional flow reserve overestimate severity of LAD lesions?

BACKGROUND: Fractional Flow Reserve (FFR) is increasingly used to estimate the severity of coronary stenoses, prior to coronary revascularization. However, it has been suggested that FFR overestimates the severity of Left Anterior Descending (LAD) lesions. Our aim was to verify whether in patients without ischemia on Myocardial Perfusion Imaging, FFR of the LAD is more often abnormal in comparison to FFR of other coronary arteries. METHODS: Prospective cohort study of consecutive patients who underwent FFR measurement because of persistent or worsening of angina complaints, within 6 months after normal Myocardial Perfusion Imaging. FFR measurements of a graft or diagonal branch were excluded. A FFR ≤ 0.80 denoted a functionally relevant stenosis. RESULTS: In 133 patients, 167 FFR measurements were performed, of which 85 in the LAD. Mean age of the patients was 64.8 ± 10.5 years, 40% were women. There were no differences in baseline characteristics between patients undergoing LAD and non-LAD measurements. An abnormal FFR was observed in 35.3% of the LAD measurements, compared to 9.8% in the non-LAD measurements (P = 0.001). Also after adjusting for age and gender, the FFR remained more frequently abnormal in the LAD with OR 5.2 (95% CI 2.2 to 12.3). Of the abnormal FFR LAD measurements, 70% were visually considered non-obstructive on invasive angiography. CONCLUSIONS: In selected patients without ischemia on MPI, FFR measurement of the LAD is significantly more often abnormal. The majority of these patients has no obstructive lesions on invasive angiography. Possibly, FFR overestimates severity of LAD lesions, with risk of unnecessary revascularization.

SUV variability in EARL-accredited conventional and digital PET.

BACKGROUND: A high SUV-reproducibility is crucial when different PET scanners are in use. We evaluated the SUV variability in whole-body FDG-PET scans of patients with suspected or proven cancer using an EARL-accredited conventional and digital PET scanner. In a head-to-head comparison we studied images of 50 patients acquired on a conventional scanner (cPET, Ingenuity TF PET/CT, Philips) and compared them with images acquired on a digital scanner (dPET, Vereos PET/CT, Philips). The PET scanning order was randomised and EARL-compatible reconstructions were applied. We measured SUVmean, SUVpeak, SUVmax and lesion diameter in up to 5 FDG-positive lesions per patient. The relative difference ΔSUV between cPET and dPET was calculated for each SUV-parameter. Furthermore, we calculated repeatability coefficients, reflecting the 95% confidence interval of ΔSUV. RESULTS: We included 128 lesions with an average size of 19 ± 14 mm. Average ΔSUVs were 6-8% with dPET values being higher for all three SUV-parameters (p < 0.001). ΔSUVmax was significantly higher than ΔSUVmean (8% vs. 6%, p = 0.002) and than ΔSUVpeak (8% vs. 7%, p = 0.03). Repeatability coefficients across individual lesions were 27% (ΔSUVmean and ΔSUVpeak) and 33% (ΔSUVmax) (p < 0.001). CONCLUSIONS: With EARL-accredited conventional and digital PET, we found a limited SUV variability with average differences up to 8%. Furthermore, only a limited number of lesions showed a SUV difference of more than 30%. These findings indicate that EARL standardisation works. TRIAL REGISTRATION: This prospective study was registered on the 31th of October 2017 at ClinicalTrials.cov. URL: https://clinicaltrials.gov/ct2/show/NCT03457506?id=03457506&rank=1.

Coronary calcium score influences referral for invasive coronary angiography after normal myocardial perfusion SPECT.

BACKGROUND: In patients with normal SPECT but persistent complaints, invasive angiography may exclude obstructive coronary disease. We assessed whether high coronary artery calcium (CAC) scores are associated with increased referral for invasive angiography following normal SPECT. METHODS AND RESULTS: 2286 consecutive patients (mean age 60 ± 12, 39% male) with normal SPECT were assessed. All patients underwent simultaneous CAC scoring. Patients were categorized into four groups based on their CAC score: CAC = 0 (n = 694), CAC 1 to 100 (n = 891), CAC 101 to 400 (n = 368), and CAC >400 (n = 333). The decision to perform angiography was left to the discretion of treating physician. Follow-up angiography was confined to the first 60 days after SPECT. Occurrence of MACE (late revascularization, myocardial infarction or death) was recorded. Overall, 100 patients (4.4%) underwent early angiography with increasing rates in higher CAC score groups (1.0%, 2.6%, 8.4%, and 11.7%), respectively, P < .001). A CAC score >400 (OR 3.56, 95% CI 2.19 to 5.77, P < .001) was independently associated with referral to angiography. Similarly, CAC score >400 was an independent predictor for MACE (HR 9.26, 95% CI 5.06 to 16.93). Early angiography did not influence prognosis (HR 1.57, 95% CI 0.91 to 2.73). CONCLUSIONS: CAC scoring impacts clinical decision-making and increases referral rates for invasive angiography after normal SPECT.

Anatomically and functionally relevant coronary stenoses in patients with normal single-photon emission computed tomography but persistent stable angina.

Aims: Single-photon emission computed tomography (SPECT) is widely used for the assessment of coronary artery disease and for decision making regarding revascularization. Concerns about possible false negative findings exist. Our aim was to assess the prevalence of stenoses which are both functionally and anatomically significant in patients referred for invasive fractional flow reserve (FFR) measurements following a normal SPECT, because of persistent complaints. Methods and results: One hundred and thirty-three consecutive patients with normal SPECT were included, with a total of 180 FFR measurements. Luminal narrowing of ≥70% (≥50% for left main) together with a FFR ≤0.80 denoted an anatomically and functionally significant coronary artery stenosis. Separate analyses were performed for FFR <0.75. Mean age of the patients was 65, 40% were women. Sixteen percent of the study population had both anatomically and functionally significant stenoses. Besides the use of nitrate, no differences in baseline characteristics, symptoms, coronary history, or pre-test likelihood could be identified for the prediction of functionally relevant obstructive coronary disease. If FFR <0.75 was used, only 7.5% of the patients had both anatomically and functionally significant stenoses. Conclusion: In patients with normal SPECT who undergo FFR measurements because of persistent complaints, the prevalence of stenoses which are both anatomically and functionally significant is low. This suggests that the prevalence of false-negative SPECT is (very) low.

Diagnostic implications of a small-voxel reconstruction for loco-regional lymph node characterization in breast cancer patients using FDG-PET/CT.

BACKGROUND: We evaluated the diagnostic implications of a small-voxel reconstruction for lymph node characterization in breast cancer patients, using state-of-the-art FDG-PET/CT. We included 69 FDG-PET/CT scans from breast cancer patients. PET data were reconstructed using standard 4 × 4 × 4 mm3 and small 2 × 2 × 2 mm3 voxels. Two hundred thirty loco-regional lymph nodes were included, of which 209 nodes were visualised on PET/CT. All nodes were visually scored as benign or malignant, and SUVmax and TBratio(=SUVmax/SUVbackground) were measured. Final diagnosis was based on histological or imaging information. We determined the accuracy, sensitivity and specificity for both reconstruction methods and calculated optimal cut-off values to distinguish benign from malignant nodes. RESULTS: Sixty-one benign and 169 malignant lymph nodes were included. Visual evaluation accuracy was 73% (sensitivity 67%, specificity 89%) on standard-voxel images and 77% (sensitivity 78%, specificity 74%) on small-voxel images (p = 0.13). Across malignant nodes visualised on PET/CT, the small-voxel score was more often correct compared with the standard-voxel score (89 vs. 76%, p <  0.001). In benign nodes, the standard-voxel score was more often correct (89 vs. 74%, p = 0.04). Quantitative data were based on the 61 benign and 148 malignant lymph nodes visualised on PET/CT. SUVs and TBratio were on average 3.0 and 1.6 times higher in malignant nodes compared to those in benign nodes (p <  0.001), on standard- and small-voxel PET images respectively. Small-voxel PET showed average increases in SUVmax and TBratio of typically 40% over standard-voxel PET. The optimal SUVmax cut-off using standard-voxels was 1.8 (sensitivity 81%, specificity 95%, accuracy 85%) while for small-voxels, the optimal SUVmax cut-off was 2.6 (sensitivity 78%, specificity 98%, accuracy 84%). Differences in accuracy were non-significant. CONCLUSIONS: Small-voxel PET/CT improves the sensitivity of visual lymph node characterization and provides a higher detection rate of malignant lymph nodes. However, small-voxel PET/CT also introduced more false-positive results in benign nodes. Across all nodes, differences in accuracy were non-significant. Quantitatively, small-voxel images require higher cut-off values. Readers have to adapt their reference standards.

Value of automatic patient motion detection and correction in myocardial perfusion imaging using a CZT-based SPECT camera.

BACKGROUND: Correction of motion has become feasible on cadmium-zinc-telluride (CZT)-based SPECT cameras during myocardial perfusion imaging (MPI). Our aim was to quantify the motion and to determine the value of automatic correction using commercially available software. METHODS AND RESULTS: We retrospectively included 83 consecutive patients who underwent stress-rest MPI CZT-SPECT and invasive fractional flow reserve (FFR) measurement. Eight-minute stress acquisitions were reformatted into 1.0- and 20-second bins to detect respiratory motion (RM) and patient motion (PM), respectively. RM and PM were quantified and scans were automatically corrected. Total perfusion deficit (TPD) and SPECT interpretation-normal, equivocal, or abnormal-were compared between the noncorrected and corrected scans. Scans with a changed SPECT interpretation were compared with FFR, the reference standard. Average RM was 2.5 ± 0.4 mm and maximal PM was 4.5 ± 1.3 mm. RM correction influenced the diagnostic outcomes in two patients based on TPD changes ≥7% and in nine patients based on changed visual interpretation. In only four of these patients, the changed SPECT interpretation corresponded with FFR measurements. Correction for PM did not influence the diagnostic outcomes. CONCLUSION: Respiratory motion and patient motion were small. Motion correction did not appear to improve the diagnostic outcome and, hence, the added value seems limited in MPI using CZT-based SPECT cameras.

Changes in cardiovascular medication after coronary artery calcium scanning and normal single photon emission computed tomography myocardial perfusion imaging in symptomatic patients.

The impact of coronary artery calcium (CAC) scoring on subsequent changes in cardiovascular medication use in symptomatic patients with normal myocardial perfusion imaging (MPI) findings is not well established. The aim of the current study was to evaluate changes in aspirin and statin use in patients suspected for coronary artery disease after CAC scoring and normal single photon emission computed tomography (SPECT) MPI. METHODS: In the current study, 1,033 stable symptomatic patients without a known history of coronary artery disease with normal SPECT MPI who underwent concomitant CAC scoring were included. All patients had a clinical indication for imaging, mainly atypical chest pain and dyspnea, and were referred from the outpatient clinic of our hospital. Data regarding posttest medication change (either starting or discontinuation of aspirin and statin therapy at the subsequent outpatient visit) were retrospectively collected. Patients were categorized into 4 groups based on their CAC score. RESULTS: Mean age of the patients was 61±11 years and 39% were male. At baseline, 35% of the patients used aspirin and 39% used statin. In patients with CAC scores 0, 1-99, 100-399, and ≥400, aspirin was started in 1%, 4%, 9%, and 9%, respectively, and statin was started in 0%, 7%, 18%, and 24% of the patients, respectively (P<.001). Aspirin was discontinued in 19%, 11%, 7%, and 1% and statin was discontinued in 8%, 6%, 2%, and 0% (P<.001) of the patients in these respective CAC score categories. After correction for differences in risk factors and baseline medication use, increased CAC was independently associated with posttest aspirin (odds ratio 4.6, 11.2, and 27.1 for CAC scores 1-99, 100-399, and ≥400, respectively; P<.001) and statin use (odds ratio 4.4, 19.4, and 60.9 for CAC scores 1-99, 100-399, and ≥400, respectively; P<.001). CONCLUSIONS: Higher CAC scores are associated with the initiation of aspirin and statin therapy in patients with normal SPECT MPI. In patients with lower CAC scores, discontinuation of cardioprotective medication is more likely. CAC score is independently associated with posttest statin and aspirin use.

Prognostic Value of Myocardial Perfusion Imaging with a Cadmium-Zinc-Telluride SPECT Camera in Patients Suspected of Having Coronary Artery Disease.

The prognostic value of myocardial perfusion imaging (MPI) with the cadmium-zinc-telluride (CZT) SPECT camera is not well established. Therefore, the aim of the current study was to evaluate the prognostic value of MPI performed with a CZT SPECT camera in a large cohort of patients suspected of having coronary artery disease. Methods: Consecutive symptomatic stable patients (n = 4,057) without a history of coronary artery disease underwent CZT SPECT MPI. During a median follow-up of 2.4 y (25th-75th percentile, 1.7-3.4), patients were monitored for primary (nonfatal myocardial infarction and cardiac mortality) and secondary outcomes (late revascularization [>90 d after scanning] and primary outcome). Results: Patients with normal perfusion demonstrated low annual event rates (primary outcome, 0.2%; secondary outcome, 0.6%). Annual event rates increased with the extent of abnormality of myocardial perfusion. In patients with small ischemic perfusion defects, annual event rates were 0.7% and 2.8% for the primary and secondary outcome, respectively. In patients with moderate or large ischemic perfusion defects, these event rates were 1.2% and 4.3%, respectively. After multivariate analysis, the risk for events was significantly associated with the extent of ischemia (hazard ratio for small ischemic defects: 2.2, 95% confidence interval [CI], 0.9-5.9 and 4.6, 95% CI, 2.8-7.6, for primary and secondary outcomes, respectively; hazard ratio for moderate or large ischemic defects: 4.0, 95% CI, 1.5-10.5 and 12.1, 95% CI, 7.2-20.2, for primary and secondary outcomes, respectively). Conclusion: Our findings show that MPI acquired with a CZT SPECT camera provides excellent prognostic information, with low event rates in patients with normal myocardial perfusion. In patients with abnormal SPECT MPI, the extent of abnormality is independently associated with an increased risk of events.

Digital PET compliance to EARL accreditation specifications.

BACKGROUND: Our aim was to evaluate if a recently introduced TOF PET system with digital photon counting technology (Philips Healthcare), potentially providing an improved image quality over analogue systems, can fulfil EANM research Ltd (EARL) accreditation specifications for tumour imaging with FDG-PET/CT. FINDINGS: We have performed a phantom study on a digital TOF PET system using a NEMA NU2-2001 image quality phantom with six fillable spheres. Phantom preparation and PET/CT acquisition were performed according to the European Association of Nuclear Medicine (EANM) guidelines. We made list-mode ordered-subsets expectation maximization (OSEM) TOF PET reconstructions, with default settings, three voxel sizes (4 × 4 × 4 mm3, 2 × 2 × 2 mm3 and 1 × 1 × 1 mm3) and with/without point spread function (PSF) modelling. On each PET dataset, mean and maximum activity concentration recovery coefficients (RCmean and RCmax) were calculated for all phantom spheres and compared to EARL accreditation specifications. The RCs of the 4 × 4 × 4 mm3 voxel dataset without PSF modelling proved closest to EARL specifications. Next, we added a Gaussian post-smoothing filter with varying kernel widths of 1-7 mm. EARL specifications were fulfilled when using kernel widths of 2 to 4 mm. CONCLUSIONS: TOF PET using digital photon counting technology fulfils EARL accreditation specifications for FDG-PET/CT tumour imaging when using an OSEM reconstruction with 4 × 4 × 4 mm3 voxels, no PSF modelling and including a Gaussian post-smoothing filter of 2 to 4 mm.

Sequential SPECT/CT imaging for detection of coronary artery disease in a large cohort: evaluation of the need for additional imaging and radiation exposure.

BACKGROUND: Performing both single photon emission computerized tomography (SPECT) and coronary computed tomography angiography (CCTA) in patients suspected for coronary artery disease (CAD) leads to increased radiation exposure. We evaluated the need for additional imaging and following implications for radiation exposure of a sequential SPECT/computed tomography (CT) algorithm. METHODS AND RESULTS: 5018 consecutive patients without history of CAD were referred for stress-first SPECT and coronary artery calcium (CAC) scoring. If stress SPECT was abnormal, additional rest SPECT and, if feasible, CCTA were acquired. Stress SPECT was normal in 2617 patients (52%). CCTA was not performed in 1289 of the 2401 patients referred for additional imaging (54%), mainly because of severe CAC (47%) or fast/irregular heart rate (22%). 642 patients with abnormal SPECT underwent CCTA, which excluded significant CAD in 378 patients (59%). Mean radiation dose was 4.5 ± 0.3 mSv for stress-only imaging and 13.2 ± 3.3 mSv for additional imaging (P < 0.001). CONCLUSIONS: Half of the patients do not require additional imaging in our sequential SPECT/CT algorithm, which is accompanied with low radiation exposure. CCTA cannot be performed in half of the patients who undergo additional imaging because of (relative) contra-indications. CCTA is able to correct for false-positive SPECT findings in our algorithm.

Sequential SPECT/CT imaging starting with stress SPECT in patients with left bundle branch block suspected for coronary artery disease.

OBJECTIVES: To investigate the impact of left bundle branch block (LBBB) on sequential single photon emission computed tomography (SPECT)/ CT imaging starting with stress-first SPECT. METHODS: Consecutive symptomatic low- to intermediate-risk patients without a history of coronary artery disease (CAD) referred for SPECT/CT were included from an observational registry. If stress SPECT was abnormal, additional rest SPECT and, if feasible, coronary CT angiography (CCTA) were acquired. RESULTS: Of the 5,018 patients, 218 (4.3 %) demonstrated LBBB. Patients with LBBB were slightly older than patients without LBBB (65±12 vs. 61±11 years, p<0.001). Stress SPECT was more frequently abnormal in patients with LBBB (82 % vs. 46 %, p<0.001). After reviewing stress and rest images, SPECT was normal in 43 % of the patients with LBBB, compared to 77 % of the patients without LBBB (p<0.001). Sixty-four of the 124 patients with LBBB and abnormal stress-rest SPECT underwent CCTA (52 %), which could exclude obstructive CAD in 46 of the patients (72 %). CONCLUSIONS: Sequential SPECT/CT imaging starting with stress SPECT is not the optimal imaging protocol in patients with LBBB, as the majority of these patients have potentially false-positive stress SPECT. First-line testing using CCTA may be more appropriate in low- to intermediate-risk patients with LBBB. KEY POINTS: • Stress-first SPECT imaging is attractive if many patients demonstrate normal stress perfusion. • The majority of left bundle branch block patients have abnormal stress-first SPECT. • Coronary CT excluded obstructive CAD in many LBBB patients with abnormal SPECT. • Stress-first SPECT imaging is not the optimal imaging protocol in LBBB patients. • In LBBB patients imaging with initial coronary CT may be more appropriate.

Impact of new X-ray technology on patient dose in pacemaker and implantable cardioverter defibrillator (ICD) implantations.

PURPOSE: New X-ray technology providing new image processing techniques may reduce radiation exposure. The aim of this study was to quantify this radiation exposure reduction for patients during pacemaker and implantable cardioverter defibrillator (ICD) implantation. METHODS: In this retrospective study, 1185 consecutive patients who had undergone de novo pacemaker or ICD implantation during a 2-year period were included. All implantations in the first year were performed using the reference technology (Allura Xper), whereas in the second year, the new X-ray technology (AlluraClarity) was used. Radiation exposure, expressed as the dose area product (DAP), was compared between the two time periods to determine the radiation exposure reduction for pacemaker and ICD implantations without cardiac resynchronization therapy (CRT) and with CRT. Procedure duration and contrast volume were used as measures to compare complexity and image quality. RESULTS: The study population consisted of 591 patients who had undergone an implantation using the reference technology, and 594 patients with the new X-ray technology. The two groups did not differ in age, gender, or body mass index. The DAP decreased with 69 % from 16.4 ± 18.5 to 5.2 ± 6.6 Gy cm2 for the non-CRT implantations (p < 0.001). The DAP decreased with 75 % from 72.1 ± 60.0 to 17.8 ± 17.4 Gy cm2 for the CRT implantations (p < 0.001). Nevertheless, procedure duration and contrast volume did not differ when using the new technology (p = 0.09 and p = 0.20, respectively). CONCLUSIONS: Introduction of new X-ray technology resulted in a radiation exposure reduction of more than 69 % for patients during pacemaker and ICD implantation while image quality was unaffected.

Impact of Gender on the Prognostic Value of Coronary Artery Calcium in Symptomatic Patients With Normal Single-Photon Emission Computed Tomography Myocardial Perfusion.

The coronary artery calcium (CAC) score provides independent prognostic value on top of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). We sought to determine whether the prognostic value of the CAC score in patients with normal SPECT MPI is gender specific. We studied 3,705 consecutive symptomatic patients without a history of coronary artery disease with normal SPECT MPI. All patients underwent concomitant CAC scoring, which was categorized as CAC score 0, 1 to 99, 100 to 399, 400 to 999, or ≥1,000. Major adverse cardiac events were defined as revascularization, nonfatal myocardial infarction, or all-cause mortality. The median CAC score was 9 in women (interquartile range 0 to 113) and 47 in men (interquartile range 1 to 307, p <0.001). The annual event rate was lower in women than in men (1.6% and 2.7%, respectively, p <0.001). When stratified by CAC score, annual event rates were similar (for women and men, respectively: CAC score 0, 0.6% and 0.5%, p = 0.95; CAC score 1 to 99, 0.9% and 1.2%, p = 0.45; CAC score 100 to 399, 2.7% and 3.8%, p = 0.23; CAC score 400 to 999, 3.8% and 5.3%, p = 0.34; CAC score ≥1,000, 8.4% and 8.7%, p = 0.99). The CAC score was an independent predictor of major adverse cardiac events in both genders (CAC score ≥1,000: hazard ratio for women 8.5, 95% confidence interval 4.0 to 18.1; hazard ratio for men 14.8, 95% confidence interval 5.3 to 41.1). In conclusion, risk for events is similar for both genders when stratified by CAC score, wherein a high CAC score carries a high risk for events despite normal SPECT MPI. Our findings do not reveal a gender-specific prognostic value of the CAC score.

Technical note: how to determine the FDG activity for tumour PET imaging that satisfies European guidelines.

BACKGROUND: For tumour imaging with PET, the literature proposes to administer a patient-specific FDG activity that depends quadratically on a patient's body weight. However, a practical approach on how to implement such a protocol in clinical practice is currently lacking. We aimed to provide a practical method to determine a FDG activity formula for whole-body PET examinations that satisfies both the EANM guidelines and this quadratic relation. RESULTS: We have developed a methodology that results in a formula describing the patient-specific FDG activity to administer. A PET study using the NEMA NU-2001 image quality phantom forms the basis of our method. This phantom needs to be filled with 2.0 and 20.0 kBq FDG/mL in the background and spheres, respectively. After a PET acquisition of 10 min, a reconstruction has to be performed that results in sphere recovery coefficients (RCs) that are within the specifications as defined by the EANM Research Ltd (EARL). By performing reconstructions based on shorter scan durations, the minimal scan time per bed position (T min) needs to be extracted using an image coefficient of variation (COV) of 15 %. At T min, the RCs should be within EARL specifications as well. Finally, the FDG activity (in MBq) to administer can be described by [Formula: see text] with c a constant that is typically 0.0533 (MBq/kg(2)), w the patient's body weight (in kg), and t the scan time per bed position that is chosen in a clinical setting (in seconds). We successfully demonstrated this methodology using a state-of-the-art PET/CT scanner. CONCLUSIONS: We provide a practical method that results in a formula describing the FDG activity to administer to individual patients for whole-body PET examinations, taking into account both the EANM guidelines and a quadratic relation between FDG activity and patient's body weight. This formula is generally applicable to any PET system, using a specified image reconstruction and scan time per bed position.

Prognostic Value of Coronary Artery Calcium Scoring in Addition to Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging in Symptomatic Patients.

BACKGROUND: The prognostic value of coronary artery calcium (CAC) scoring on top of myocardial perfusion imaging with single-photon emission computed tomography (SPECT) in patients suspected for coronary artery disease is not well established. METHODS AND RESULTS: Four thousand eight hundred ninety-seven symptomatic patients without a history of coronary artery disease referred for SPECT and CAC scoring were included. Major adverse cardiac events (MACEs) were defined as late revascularization (>90 days after scanning), nonfatal myocardial infarction, and all-cause mortality. The frequency of abnormal SPECT increased with higher CAC scores, from 12% in patients with CAC scores of 0 to 19%, 32%, 37%, and 50% among those with CAC scores 1 to 99, 100 to 399, 400 to 999, and ≥1000, respectively (P<0.001). During a median follow-up of 940 days (25th to 75th percentile, 581-1377), a total of 278 MACEs were observed. Overall incidence of MACE was 2.3% per year. A stepwise increase of MACE was present with increasing CAC scores, both in patients with normal SPECT (annual event rate CAC score 0: 0.6%; CAC score ≥1000: 5.5%) and abnormal SPECT (annual event rate CAC score 0: 0.4%; CAC score ≥1000: 7.6%). After multivariate analysis, both SPECT and CAC score were independent predictors of MACE (CAC score ≥1000: hazard ratio, 7.7; P<0.001 and large perfusion defect on SPECT: hazard ratio, 3.7; P<0.001). CONCLUSIONS: CAC score and SPECT are independent predictors of MACE in patients suspected for coronary artery disease. Our findings strongly support performing a CAC score in addition to SPECT in symptomatic patients to better define the risk of events during follow-up.

Prognostic value of normal stress-only myocardial perfusion imaging: a comparison between conventional and CZT-based SPECT.

PURPOSE: Single photon emission computed tomography (SPECT) myocardial perfusion imaging has proven to have prognostic importance in patients with suspected stable coronary artery disease (CAD). The recently introduced ultrafast cadmium zinc telluride (CZT)-based gamma cameras have been associated with less equivocal findings and more normal interpretations, allowing stress-only imaging to be performed more often. However, it is yet unclear whether normal stress-only CZT SPECT has comparable prognostic value as normally interpreted stress-only conventional SPECT. METHODS: The study population consisted of 1,650 consecutive patients without known CAD with normal stress-only myocardial perfusion results with either conventional (n = 362) or CZT SPECT (n = 1,288). The incidence of major adverse cardiac events (MACE, all-cause death, non-fatal myocardial infarction and/or coronary revascularization) was compared between the conventional SPECT and CZT SPECT groups. Multivariable analyses using the Cox model were used to adjust for differences in baseline variables. RESULTS: Patients scanned with CZT were less often male (33 vs 39 %), had less often hypercholesterolaemia (41 vs 50 %) and had more often a family history of CAD (57 vs 49 %). At a median follow-up time of 37 months (interquartile range 28-45 months) MACE occurred in 68 patients. The incidence of MACE was 1.5 %/year in the CZT group, compared to 2.0 %/year in the conventional group (p = 0.08). After multivariate analyses, there was a trend to a lower incidence of MACE in the CZT SPECT group (hazard ratio 0.61, 95 % confidence interval 0.35-1.04, p = 0.07). CONCLUSION: The prognostic value of normal stress-only CZT SPECT is at least comparable and may be even better than that of normal conventional stress SPECT.