BackgroundCardiac imaging by means of myocardial Positron Emission Tomography/Computed Tomography (PET/CT) is being used increasingly to assess coronary artery disease, to guide revascularization decisions with more accuracy, and it allows robust quantitative analysis of both regional myocardial blood flow (MBF) and myocardial flow reserve (MFR).Recently, a more time-efficient protocol has been developed in combination with a residual activity correction algorithm in which a stress acquisition is performed directly after completion of the rest acquisition to subtract remaining myocardial radioactivity.The objective of this study is to define flow values of myocardial blood flow (MBF) and Myocardial Flow Reserve (MFR) with 13N–ammonia (13NH3) myocardial perfusion PET/CT on patients without coronary artery disease using a time-efficient protocol, since reference values for this particular type of study are lacking in literature. In addition, we aim to determine the effect of the residual activity correction algorithm in this time-efficient protocol.ResultsA mean MBF in rest of 1.02 ± 0.22 ml/g/min, a mean MBF in stress of 2.54 ± 0.41 ml/g/min with a mean MFR of 2.60 ± 0.61 were measured. Female patients had a significant higher MBF in rest and stress, but lower MFR; a small but significant negative correlation was measured between age and MBF in stress and MFR. Residual activity correction had a significant effect resulting in a difference in global stress MBF before and after correction of 0.39 ± 0.13 ml/g/min.ConclusionsThis study established flow values for 13NH3 myocardial PET/CT with a time-efficient protocol, and established that MBF in stress corrected for residual activity is comparable with known reference values in normal studies without temporal overlap. Further validation of the technique could be of value, e.g. by comparison to standard imaging without temporal overlap, or validation against catheterization results.Electronic supplementary materialThe online version of this article (10.1186/s41824-018-0029-z) contains supplementary material, which is available to authorized users.
Since 1981, 40 patients with advanced breast carcinoma have been treated with megavoltage radiotherapy combined with hyperthermia. The irradiation dose to the primary tumour was 50 Gy/25 fractions, five fractions per week. Hyperthermia (aim: 44 degrees C/30 min) was applied once a week, 30 minutes after the midweek radiation fraction. Tumour response did not correlate with the chance of long-term local control. The likelihood of 3-year local control was 46 per cent and 3-year survival was 52 per cent. The local tumour control rate decreased with increasing T stage and was related to non-uniformity of the temperature distribution in the heated volume. It was concluded that (a) the radiation dose should be increased and (b) the temperature uniformity should be improved.
Funding Acknowledgements Type of funding sources: None. Background Coronary artery calcium (CAC) is a well-known predictor of major adverse cardiac events and is scored manually from dedicated, ECG-triggered CT scans. In the present study, we investigated the accuracy of risk categorisation based on visual and automatic AI calcium scoring from low dose CT (LDCT) scans and dedicated Calcium Score CT (CSCT) scans. Purpose To assess the agreement of risk prediction based on visual and automatic AI CAC scoring from CSCT scans and LDCT scans as compared to a gold standard, manual CSCT scoring. Methods We retrospectively enrolled 222 patients. Each patient received a 13N-ammonia PET with LDCT and CSCT scan. The time interval between LDCT and CSCT was less than 6 months. Each LDCT and CSCT scan was scored visually, manually, and automatically with AI. For visual scoring we used a previously described 6–points scale (0; 1-10; 11-100; 101-400; 401-100; >1000 Agatston score). For manual scoring we used a generally available software package (Syngo.via,Siemens). The automatic AI scoring was performed with commercially available software based on a deep learning algorithm (included in Syngo.via,Siemens). Each manually and automatically measured Agatston score was converted into the 6-points scale. We performed a per patient analysis; the risk group categorization was based on the total Agatston score. Spearman correlation coefficient was used to analyse the association between manual and automatic AI scoring methods. Agreement between visual, manual, and automatic AI scoring methods was determined using weighted kappa test with 95% confidence intervals (95%CI). Results The correlation between manual scoring from LDCT and CSCT scans was 0.96 (p < 0.001).The agreement between manual scoring from two scans, however, was low with weighted kappa equal 0.57 (95% CI 0.51 – 0.63). 91,9% of calcium scores measured by AI software on CSCT were in the same risk group as manual CSCT scores.The agreement between AI scoring and manual scoring using CSCT was excellent, the weighted kappa was equal 0.95 (95% CI 0.92 - 0.97).Based on visual scoring on LDCT scans, 74,3% of the scores were in the same category as manual scoring on CSCT scans. The agreement between the visual scoring on LDCT scans and a gold standard was strong, weighted kappa equal was 0.82 (95% CI 0.77 – 0.86). The agreement between manual and automatic scoring on LDCT using manual CSCT as the gold standard was low (0.57, 95 % CI 0.51 – 0.63; 0.49, 95 % CI 0.43 – 0.56, respectively). Based on visual LDCT scoring, 7 patients were incorrectly classified as calcium score 0, which underestimated the overall patients’ risk.The AI method scoring CSCT scans, classified 2 patients incorrectly as non-calcium risk group. Conclusions CAC can be automatically assessed from CSCT scans with commercially available AI software.Of manual, automatic, and visual CAC scoring on LDCT scans the visual scoring showed the highest agreement with the gold standard manual CSCT CAC scoring.
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