Report on the development and application of PET/CT in mainland China

The diagnostic value of dual-layer CT in the assessment of lymph nodes in lymphoma patients with PET/CT as a reference standard

This study aimed to evaluate the diagnostic performances of dual-layer CT (DLCT) for the identification of positive lymph nodes (LNs) in patients with lymphoma and retrospectively included 1165 LNs obtained by biopsy from 78 patients with histologically proven lymphoma, who underwent both pretreatment DLCT and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). According to 18F-FDG PET/CT findings as a reference standard, cases were categorized into the LN-negative and LN-positive groups. LNs were then randomly divided at a ratio of 7:3 into the training (n = 809) and validation (n = 356) cohorts. The patients' clinical characteristics and quantitative parameters including spectral curve slope (λHU), iodine concentration (IC) on arterial phase (AP) and venous phase (VP) images were compared between the LN-negative and LN-positive groups using Chi-square test, t-test or Mann-Whitney U test for categorical variables or quantitative parameters. Multivariate logistic regression analysis with tenfold cross-validation was performed to establish the most efficient predictive model in the training cohort. The area under the curve (AUC) was used to evaluate the diagnostic value of the predictive model, and differences in AUC were determined by the DeLong test. Moreover, the predictive model was validated in the validation cohort. Repeatability analysis was performed for LNs using intraclass correlation coefficients (ICCs). In the training cohort, long diameter (LD) had the highest AUC as an independent factors compared to other parameter in differentiating LN positivity from LN negativity (p = 0.006 to p < 0.001), and the AUC of predictive model jointly involving LD and λHU-AP was significantly elevated (AUC of 0.816, p < 0.001). While the AUC of predictive model in the validation cohort was 0.786. Good to excellent repeatability was observed for all parameters (ICC > 0.75). The combination of DLCT with morphological and functional parameters may represent a potential imaging biomarker for detecting LN positivity in lymphoma.

Predicting 18F-FDG SUVs of metastatic pulmonary nodes from CT images in patients with differentiated thyroid cancer by using a convolutional neural network

Purpose

The aim of this study was to predict standard uptake values (SUVs) from computed tomography (CT) images of patients with lung metastases from differentiated thyroid cancer (DTC-LM).

Methods

We proposed a novel SUVs prediction model using 18-layer Residual Network for generating SUVmax, SUVmean, SUVmin of metastatic pulmonary nodes from CT images of patients with DTC-LM. Nuclear medicine specialists outlined the metastatic pulmonary as primary set. The best model parameters were obtained after five-fold cross-validation on the training and validation set, further evaluated in independent test set. Mean absolute error (MAE), mean squared error (MSE), and mean relative error (MRE) were used to assess the performance of regression task. Specificity, sensitivity, F1 score, positive predictive value, negative predictive value and accuracy were used for classification task. The correlation between predicted and actual SUVs was analyzed.

Results

A total of 3407 nodes from 74 patients with DTC-LM were collected in this study. On the independent test set, the average MAE, MSE and MRE was 0.3843, 1.0133, 0.3491 respectively, and the accuracy was 88.26%. Our proposed model achieved high metric scores (MAE=0.3843, MSE=1.0113, MRE=34.91%) compared with other backbones. The predicted SUVmax (R^{2 =} 0.8987), SUVmean (R^{2 =} 0.8346), SUVmin (R^{2 =} 0.7373) were all significantly correlated with actual SUVs.

Conclusion

The novel approach proposed in this study provides new ideas for the application of predicting SUVs for metastatic pulmonary nodes in DTC patients.

Clinical effectiveness of contrast medium injection protocols for 80-kV coronary and craniocervical CT angiography-a prospective multicenter observational study

BACKGROUND AND OBJECTIVE

Decreasing X-ray tube voltage is an effective way to reduce radiation and contrast dose, especially in non-obese patients. The current study focuses on CTA in non-obese patients to evaluate image quality and feasibility of 80-kV acquisition protocols with varying iodine delivery rates (IDR) and contrast concentrations in routine clinical practice.

METHODS

A prospective observational study in patients ≥ 18 years and ≤ 90 kg referred for coronary or craniocervical CTA at 10 centers in China (ClinicalTrials.gov: NCT02840903). Patients were divided into four groups: a standard 100-kV protocol (370 mgI/ml, IDR 1.48 gI/s), and three 80-kV protocols (370 mgI/ml, IDR 1.2 gI/s; 300 mgI/ml, IDR 1.2 gI/s; 300 mgI/ml, IDR 0.96gI/s). The primary outcome was contrast opacification of target vascular segments. Secondary outcomes were image quality (contrast-to-noise ratio, signal-to-noise ratio, visual image quality, and diagnostic confidence assessment), radiation, and iodine dose.

RESULTS

From July 2016 to July 2017, 1213 patients were enrolled: 614 coronary and 599 craniocervical CTA. The mean contrast opacification was ≥ 300 HU for 80-kV 1.2 gI/s IDR scanned segments; IDR 0.96 gI/s led to lower opacification. Image quality and diagnostic confidence were fair to excellent (≥ 98% of images), despite lower contrast-to-noise ratios and signal-to-noise ratios in 80-kV images. Compared to the standard protocol, 80-kV protocols led to 44-52% radiation dose reductions (p < 0.001) and 19% iodine dose reductions (p < 0.001).

CONCLUSION

Eighty-kilovolt 1.2 gI/s IDR protocols can be recommended for coronary and craniocervical CTA in non-obese patients, reducing radiation and iodine dose without compromising image quality.

KEY POINTS

• Using low-voltage scanning CTA protocols, in which tube voltage and iodine delivery rate are reduced proportionally (voltage: 80 kV, IDR: 1.2 gI/s), reduces radiation and contrast dose without compromising image quality in routine clinical practice. • Reducing iodine delivery rate beyond direct proportionality to tube voltage is not beneficial.

Pre-feasibility Study for Establishing Radioisotope and Radiopharmaceutical Production Facilities in Developing Countries

BACKGROUND

A significant number of developing countries have no facilities to produce medical radioisotopes and radiopharmaceuticals.

OBJECTIVE

In this paper we show that access to life-saving radioisotopes and radiopharmaceuticals and the geographical distribution of corresponding infrastructure is highly unbalanced worldwide.

METHODS

We discuss the main issues which need to be addressed in order to establish the production of radioisotopes and radiopharmaceuticals, which are especially important for developing countries as newcomers in the field. The data was gathered from several sources, including databases maintained by the International Atomic Energy Agency (IAEA), World Health Organization (WHO), and other international organizations; personal interactions with representatives in the nuclear medicine field from different regions of the world; and relevant literature.

RESULTS

Developing radioisotope and radiopharmaceutical production program and installing corresponding infrastructure requires significant investments, both man-power and financial. Support already exists to help developing countries establish their medical radioisotope production installations from several organizations, such as IAEA.

CONCLUSION

This work clearly shows that access to life-saving radioisotopes and the geographical distribution of corresponding infrastructure is highly unbalanced. Technology transfer is important as it not only immediately benefits patients, but also provides employment, economic activity and general prosperity in the region to where the technology transfer is implemented.

Nuclear cardiology in China: 2017

This paper provides the current state of nuclear cardiology in China and contrasts it with the state of nuclear cardiology in the United States (US). The West China Hospital and New York-Presbyterian Hospital (NYPH) were used as representative hospitals to contrast nuclear cardiology in China and the US, respectively. In 2015, there were 101 medical cyclotrons, 774 SPECT or SPECT/CT, 240 PET/CT, and 6 PET/MR cameras in China. Most (~90%) of the nuclear cardiology studies are gated SPECT myocardial perfusion imaging (MPI), and ~10% are other types of studies including MUGA, PET/CT MPI, and viability studies. There are differences in nuclear cardiology between the West China Hospital and NYPH and these include those in cardiac stress tests, SPECT/CT acquisition protocols, PET/CT blood flow and viability studies, reimbursement, and fellowship training. In this paper, we aim to present status of nuclear cardiology in China and provide potential solutions.