First in vivo head-to-head comparison of high-definition versus standard-definition stent imaging with 64-slice computed tomography

The aim of this study was to compare image quality characteristics from 64-slice high definition (HDCT) versus 64-slice standard definition CT (SDCT) for coronary stent imaging. In twenty-five stents of 14 patients, undergoing contrast-enhanced CCTA both on 64-slice SDCT (LightSpeedVCT, GE Healthcare) and HDCT (Discovery HD750, GE Healthcare), radiation dose, contrast, noise and stent characteristics were assessed. Two blinded observers graded stent image quality (score 1=no, 2=mild, 3=moderate, and 4=severe artefacts). All scans were reconstructed with increasing contributions of adaptive statistical iterative reconstruction (ASIR) blending (0, 20, 40, 60, 80 and 100%). Image quality was significantly superior in HDCT versus SDCT (score 1.7±0.5 vs. 2.7±0.7; p<0.05). Image noise was significantly higher in HDCT compared to SDCT irrespective of ASIR contributions (p<0.05). Addition of 40% ASIR or more reduced image noise significantly in both HDCT and SDCT. In HDCT in-stent luminal attenuation was significantly lower and mean measured in-stent luminal diameter was significantly larger (1.2±0.4mm vs. 0.8±0.4mm; p<0.05) compared to SDCT. Radiation dose from HDCT was comparable to SDCT (1.8±0.7mSv vs. 1.7±0.7mSv; p=ns). Use of HDCT for coronary stent imaging reduces partial volume artefacts from stents yielding improved image quality versus SDCT at a comparable radiation dos

Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition

To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359±61 to 54±8HU (P<0.001), the latter comparing well to the value of 64±55HU found in the standard unenhanced CT (P=ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187±321, 72±114mm3, and 27±46mg/cm3, comparing well to the values from standard unenhanced CT (187±309, 72±110mm3, and 27±45mg/cm3) yielding an excellent correlation (r=0.96, r=0.96, r=0.92; P<0.001). Mean estimated radiation dose revealed 0.83±0.02mSv from the unenhanced CT and 1.70±0.53mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction

Perfusion CT best predicts outcome after radioembolization of liver metastases: a comparison of radionuclide and CT imaging techniques

Objective: To determine the best predictor for the response to and survival with transarterial radioembolisation (RE) with 90yttrium microspheres in patients with liver metastases. Methods: Forty consecutive patients with liver metastases undergoing RE were evaluated with multiphase CT, perfusion CT and 99mTc-MAA SPECT. Arterial perfusion (AP) from perfusion CT, HU values from the arterial (aHU) and portal venous phase (pvHU) CT, and 99mTc-MAA uptake ratio of metastases were determined. Morphologic response was evaluated after 4months and available in 30 patients. One-year survival was calculated with Kaplan-Meier curves. Results: We found significant differences between responders and non-responders for AP (P 20ml/100ml/min had a significantly (P = 0.01) higher 1-year survival, whereas an aHU value >55 HU did not discriminate survival (P = 0.12). The Cox proportional hazard model revealed AP as the only significant (P = 0.02) independent predictor of survival. Conclusion: Compared to arterial and portal venous enhancement and the 99mTc-MAA uptake ratio of liver metastases, the AP from perfusion CT is the best predictor of morphologic response to and 1-year survival with RE. Key Points : • Perfusion CT allows for calculation of the liver arterial perfusion. • Arterial perfusion of liver metastases differs between responders and non-responders to RE. • Arterial perfusion can be used to select patients responding to RE

PET/MR outperforms PET/CT in suspected occult tumors

BACKGROUND To compare the diagnostic accuracy of PET/MR and PET/CT in patients with suspected occult primary tumors. METHODS This prospective study was approved by the institutional review board. Sequential PET/CT-MR was performed in 43 patients (22 male subjects; median age, 58 years; range, 20-86 years) referred for suspected occult primary tumors. Patients were assessed with PET/CT and PET/MR for the presence of a primary tumor, lymph node metastases, and distant metastases. Wilcoxon signed-rank test was performed to compare the diagnostic accuracy of PET/CT and PET/MR. RESULT According to the standard of reference, a primary lesion was found in 14 patients. In 16 patients, the primary lesion remained occult. In the remaining 13 patients, lesions proved to be benign. PET/MR was superior to PET/CT for primary tumor detection (sensitivity/specificity, 0.85/0.97 vs 0.69/0.73; P = 0.020) and comparable to PET/CT for the detection of lymph node metastases (sensitivity/specificity, 0.93/1.00 vs 0.93/0.93; P = 0.157) and distant metastases (sensitivity/specificity, 1.00/0.97 vs 0.82/1.00; P = 0.564). PET/CT tended to misclassify physiologic FDG uptake as malignancy compared with PET/MR (8 patients vs 1 patient). CONCLUSIONS PET/MR outperforms PET/CT in the workup of suspected occult malignancies. PET/MR may replace PET/CT to improve clinical workflow

Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition

To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70 keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359 ± 61 to 54 ± 8 HU (P < 0.001), the latter comparing well to the value of 64 ± 55 HU found in the standard unenhanced CT (P = ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187 ± 321, 72 ± 114 mm(3), and 27 ± 46 mg/cm(3), comparing well to the values from standard unenhanced CT (187 ± 309, 72 ± 110 mm(3), and 27 ± 45 mg/cm(3)) yielding an excellent correlation (r = 0.96, r = 0.96, r = 0.92; P < 0.001). Mean estimated radiation dose revealed 0.83 ± 0.02 mSv from the unenhanced CT and 1.70 ± 0.53 mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction

Determinants of diagnostic performance of 18F-FDG PET/CT in patients with fever of unknown origin

OBJECTIVES There is uncertainty about patient selection and the adequate timing at which fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) is indicated in the diagnostic work-up of fever of unknown origin (FUO). The aim of this study was to determine the diagnostic performance of F-FDG PET/CT in patients with FUO. METHODS All consecutive patients who underwent F-FDG PET/CT at the University Hospital Zurich because of FUO between 2006 and 2012 were included in this retrospective, observational study. RESULTS A total of 76 patients [70% men, median (interquartile range) age 60 (47-67) years] were included. F-FDG PET/CT showed characteristically increased F-FDG activity in 56 patients (74%), leading to confirmation of or change in the suspected cause of FUO in 57 and 17%, respectively. The final diagnosis after F-FDG PET/CT included infection (21%), malignancy (22%), noninfectious inflammatory disease (12%), others (5%), or an unknown cause (40%). The success rate, sensitivity, and specificity of F-FDG PET/CT were 60, 77, and 31%, respectively. Sensitivity was highest in patients with suspected malignancy (100%, 95% confidence interval 79-100%). Diagnostic performance was independent of the investigated variables other than suspected infection as a cause of FUO (odds ratio 0.1, 95% confidence interval 0.01-0.8, P=0.033). CONCLUSION The diagnostic performance of F-FDG PET/CT was significantly higher in patients with suspected malignancy causing a FUO compared with suspected infection or noninfectious inflammatory disease. However, it was independent of the baseline characteristics and duration of fever. This supports the recommendation to perform F-FDG PET/CT early in the diagnostic work-up of FUO, which may shorten disease duration and lower health costs, particularly when infection or malignancy is suspected

CT-perfusion in peripheral arterial disease - Correlation with angiographic and hemodynamic parameters

OBJECTIVE The purpose of this study was the assessment of volumetric CT-perfusion (CTP) of the lower leg musculature in patients with symptomatic peripheral arterial disease (PAD) of the lower extremities, comparing it with established angiographic and hemodynamic parameters. MATERIALS AND METHODS Thirty-five consecutive patients with symptomatic PAD of the lower extremities requiring interventional revascularization were assessed prospectively. All patients underwent a CTP scan of the lower leg, and hemodynamic and angiographic assessment. Hemodynamic parameters, specifically ankle-brachial pressure index (ABI), ankle blood pressure (ABP), peak systolic velocity (PSV), and segmental pulse oscillography (SPO) level, were determined. Lesion length and degree of collateralization were assessed by interventional angiography. CTP parameters were calculated with a perfusion software, acting on a no outflow assumption. A sequential two-compartment model was used. Differences in CTP parameters and correlations between CTP, hemodynamic and angiographic parameters were assessed with non-parametric tests. RESULTS The cohort consisted of 27 subjects with an occlusion, and eight with a high-grade stenosis. The mean blood flow (BF) was 7.71 ± 2.96 ml/100ml*min-1, mean blood volume (BV) 0.71 ± 0.33 ml/100ml, and mean mean transit time (MTT) 7.22 ± 2.66 s. BF and BV were higher in subjects with longer lesions, and BV was higher in subjects with lower ABI. Significant correlations were found between lesion length and BV (r = 0.65) and BF (r = 0.52). Significant inverse correlations were found between BV and ABI and between BV and ABP (r = -0.56, for both correlations). CONCLUSIONS In our study, we have shown the feasibility of CTP for the assessment of PAD. In the future, this quantitative method might serve as a non-invasive method, possibly complementing the diagnostic workup of patients with peripheral arterial disease

CT perfusion in peripheral arterial disease-hemodynamic differences before and after revascularisation.

OBJECTIVES The purpose of this study was the assessment of volumetric CT perfusion (CTP) of the lower leg musculature in patients with symptomatic peripheral arterial disease (PAD) before and after interventional revascularisation. METHODS Twenty-nine consecutive patients with symptomatic PAD of the lower extremities requiring interventional revascularisation were assessed prospectively. All patients underwent a CTP scan of the lower leg, and hemodynamic and angiographic assessment, before and after intervention. Ankle-brachial pressure index (ABI) was determined. CTP parameters were calculated with a perfusion software, acting on a no outflow assumption. A sequential two-compartment model was used. Differences in CTP parameters were assessed with non-parametric tests. RESULTS The cohort consisted of 24 subjects with an occlusion, and five with a high-grade stenosis. The mean blood flow before/after (BFpre and BFpost, respectively) was 7.42 ± 2.66 and 10.95 ± 6.64 ml/100 ml*min-1. The mean blood volume before/after (BVpre and BVpost, respectively) was 0.71 ± 0.35 and 1.25 ± 1.07 ml/100 ml. BFpost and BVpost were significantly higher than BFpre and BVpre in the treated limb (p = 0.003 and 0.02, respectively), but not in the untreated limb (p = 0.641 and 0.719, respectively). CONCLUSIONS CTP seems feasible for assessing hemodynamic differences in calf muscles before and after revascularisation in patients with symptomatic PAD. We could show that CTP parameters BF and BV are significantly increased after revascularisation of the symptomatic limb. In the future, this quantitative method might serve as a non-invasive method for surveillance and therapy control of patients with peripheral arterial disease. KEY POINTS • CTP imaging of the lower limb in patients with symptomatic PAD seems feasible for assessing hemodynamic differences before and after revascularisation in PAD patients. • This quantitative method might serve as a non-invasive method, for surveillance and therapy control of patients with PAD

Radiomics in esophageal and gastric cancer

Esophageal, esophago-gastric, and gastric cancers are major causes of cancer morbidity and cancer death. For patients with potentially resectable disease, multi-modality treatment is recommended as it provides the best chance of survival. However, quality of life may be adversely affected by therapy, and with a wide variation in outcome despite multi-modality therapy, there is a clear need to improve patient stratification. Radiomic approaches provide an opportunity to improve tumor phenotyping. In this review we assess the evidence to date and discuss how these approaches could improve outcome in esophageal, esophago-gastric, and gastric cancer