Accurate Measurement of Agatston Score Using kVp-Independent Reconstruction Algorithm for Ultra-High-Pitch Sn150 kVp CT

ObjectiveTo investigate the accuracy of the Agatston score obtained with the ultra-high-pitch (UHP) acquisition mode using tin-filter spectral shaping (Sn150 kVp) and a kVp-independent reconstruction algorithm to reduce the radiation dose.Materials and MethodsThis prospective study included 114 patients (mean ± standard deviation, 60.3 ± 9.8 years; 74 male) who underwent a standard 120 kVp scan and an additional UHP Sn150 kVp scan for coronary artery calcification scoring (CACS). These two datasets were reconstructed using a standard reconstruction algorithm (120 kVp + Qr36d, protocol A; Sn150 kVp + Qr36d, protocol B). In addition, the Sn150 kVp dataset was reconstructed using a kVp-independent reconstruction algorithm (Sn150 kVp + Sa36d, protocol C). The Agatston scores for protocols A and B, as well as protocols A and C, were compared. The agreement between the scores was assessed using the intraclass correlation coefficient (ICC) and the Bland–Altman plot. The radiation doses for the 120 kVp and UHP Sn150 kVp acquisition modes were also compared.ResultsNo significant difference was observed in the Agatston score for protocols A (median, 63.05; interquartile range [IQR], 0–232.28) and C (median, 60.25; IQR, 0–195.20) (p = 0.060). The mean difference in the Agatston score for protocols A and C was relatively small (−7.82) and with the limits of agreement from −65.20 to 49.56 (ICC = 0.997). The Agatston score for protocol B (median, 34.85; IQR, 0–120.73) was significantly underestimated compared with that for protocol A (p < 0.001). The UHP Sn150 kVp mode facilitated an effective radiation dose reduction by approximately 30% (0.58 vs. 0.82 mSv, p < 0.001) from that associated with the standard 120 kVp mode.ConclusionThe Agatston scores for CACS with the UHP Sn150 kVp mode with a kVp-independent reconstruction algorithm and the standard 120 kVp demonstrated excellent agreement with a small mean difference and narrow agreement limits. The UHP Sn150 kVp mode allowed a significant reduction in the radiation dose.     

A study of using a deep learning image reconstruction to improve the image quality of extremely low-dose contrast-enhanced abdominal CT for patients with hepatic lesions

Objective:To investigate the feasibility of using deep learning image reconstruction (DLIR) to significantly reduce radiation dose and improve image quality in contrast-enhanced abdominal CT.Methods:This was a prospective study. 40 patients with hepatic lesions underwent abdominal CT using routine dose (120kV, noise index (NI) setting of 11 with automatic tube current modulation) in the arterial-phase (AP) and portal-phase (PP), and low dose (NI = 24) in the delayed-phase (DP). All images were reconstructed at 1.25 mm thickness using ASIR-V at 50% strength. In addition, images in DP were reconstructed using DLIR in high setting (DLIR-H). The CT value and standard deviation (SD) of hepatic parenchyma, spleen, paraspinal muscle and lesion were measured. The overall image quality includes subjective noise, sharpness, artifacts and diagnostic confidence were assessed by two radiologists blindly using a 5-point scale (1, unacceptable and 5, excellent). Dose between AP and DP was compared, and image quality among different reconstructions were compared using SPSS20.0.Results:Compared to AP, DP significantly reduced radiation dose by 76% (0.76 ± 0.09 mSv vs 3.18 ± 0.48 mSv), DLIR-H DP images had lower image noise (14.08 ± 2.89 HU vs 16.67 ± 3.74 HU, p < 0.001) but similar overall image quality score as the ASIR-V50% AP images (3.88 ± 0.34 vs 4.05 ± 0.44, p > 0.05). For the DP images, DLIR-H significantly reduced image noise in hepatic parenchyma, spleen, muscle and lesion to (14.77 ± 2.61 HU, 14.26 ± 2.67 HU, 14.08 ± 2.89 HU and 16.25 ± 4.42 HU) from (24.95 ± 4.32 HU, 25.42 ± 4.99 HU, 23.99 ± 5.26 HU and 27.01 ± 7.11) with ASIR-V50%, respectively (all p < 0.001) and improved image quality score (3.88 ± 0.34 vs 2.87 ± 0.53; p < 0.05).Conclusion:DLIR-H significantly reduces image noise and generates images with clinically acceptable quality and diagnostic confidence with 76% dose reduction.Advances in knowledge:(1) DLIR-H yielded a significantly lower image noise, higher CNR and higher overall image quality score and diagnostic confidence than the ASIR-V50% under low signal conditions. (2) Our study demonstrated that at 76% lower radiation dose, the DLIR-H DP images had similar overall image quality to the routine-dose ASIR-V50% AP images.     

Correlation between thoracic aorta 18F-natrium fluoride uptake and cardiovascular risk

AIM: To investigating the relationship between thoracic and cardiac ¹⁸F-Natrium-Fluoride (18F-NaF) uptake, as a marker of ongoing calcification and cardiovascular risk factors.METHODS: Seventy-eight patients (44 females, mean age 63, range 44-83) underwent whole body 18F-NaF positron emission tomography/computed tomography. Cardiovascular risk (CVR) was used to divide these patients in three categories: Low (LR), medium (MR) and high risk (HR). 18F-NaF uptake was measured by manually drawing volumes of interest on the ascending aorta, on the aortic arch, on the descending aorta and on the myocardium; average standardized uptake value was normalized for blood-pool, to obtain target-to-background ratio (TBR). Values from the three aortic segments were then averaged to obtain an index of the whole thoracic aorta.RESULTS: A significant difference in whole thoracic aorta TBR was detected between HR and LR (1.84 ± 0.76 vs 1.07 ± 0.3, P < 0.001), but also between MR and HR-LR (1.4 ± 0.4, P < 0.02 and P < 0.01, respectively). Significance of this TBR stratification strongly varied among thoracic aorta subsegments and the lowest P values were reached in the descending aorta (P < 0.01). Myocardial uptake provided an effective CVR classes stratification (P < 0.001).Correlation between TBR and CVR was appreciable when the whole thoracic aorta was considered (R = 0.67), but it peaked when correlating the descending thoracic segment (R = 0.75), in comparison with the aortic arch and the ascending segment (R = 0.55 and 0.53, respectively).CONCLUSION: Fluoride uptake within the thoracic aorta wall effectively depicts patients’ risk class and correlates with cardiovascular risk. Descending aorta is the most effective in CVR determination.     

Low-kV coronary artery calcium scoring with tin filtration using a kV-independent reconstruction algorithm

PurposeTo investigate the accuracy of Agatston scoring and potential for radiation dose reduction of a coronary artery calcium scoring (CACS) CT protocol at 100 kV with tin filtration (Sn100kV) and kV-independent iterative reconstruction, compared to standard 120 kV acquisitions.Materials and methodsWith IRB approval and in HIPAA compliance, 114 patients (61.8 ± 9.6 years; 66 men) underwent CACS using a standard 120 kV protocol and an additional Sn100kV CACS scan. The two datasets were reconstructed using a medium sharp convolution algorithm and in addition the Sn100kV scans were reconstructed iteratively based on a kV-independent algorithm. Agatston scores and radiation dose values were compared between the Sn100kV and the standard 120 kV protocol.ResultsMedian Agatston scores derived from the Sn100kV protocol with the kV-independent algorithm and the standard 120 kV were 21.4 (IQR, 0–173.8) and 24.7 (IQR, 0–171.1) respectively, with no significant differences (p=0.18). Agatston scores derived from the two different protocols had an excellent correlation (r = 0.99). The dose-length-product was 11.5 ± 4.1 mGy × cm using Sn100kV and 50.4 ± 24.9 mGy × cm using the standard 120 kV protocol (p < 0.01), resulting in a significantly lower (77%) effective dose at Sn100kV (0.16 ± 0.06 mSv vs. 0.71 ± 0.35 mSv, p < 0.01). Additionally, 99% of the patients were classified into the same risk category (0, 1–10, 11–100, 101–400, or >400) using the Sn100kV protocol.ConclusionCACS at Sn100kV using the kV-independent iterative algorithm is feasible and provides high accuracy when compared to standard 120 kV scanning. Furthermore, radiation dose can be significantly reduced for this screening application in a priori healthy individuals.     

Gender is a determinant of carotid artery stiffness independent of age and blood pressure

Objective:To identify the gender-specific differences in carotid artery structural and stiffening parameters by radiofrequency ultrasound (RFU) with an automatic arterial stiffness analyzing system.Methods:Seventy-two consecutive individuals (32 males and 40 females, age range from 36 to 62 years) with no history of significant cardiovascular diseases or carotid artery plaques were enrolled between September and December 2017. Quality intima-media thickness (QIMT) and quality arterial stiffness (QAS) parameters were automatically computed, including pulse wave velocity (PWV), vascular distension, compliance coefficient (CC), distensibility coefficient (DC), stiffness index α and β, augmentation pressure (AP), and augmentation index (AIx). Those parameters were compared between males and females. Multiple linear regression analysis was performed to assess the independent association between gender and RFU parameters.Results:The mean age had no difference between males and females (47.8 ± 3.3 vs 50.0 ± 8.5 years, p = 0.19). Females had higher systolic blood pressure (134.53 ± 9.65 vs 127.78 ± 6.12 mm Hg) and diastolic blood pressure (85.83 ± 3.94 vs 78.03 ± 5.22 mm Hg), greater carotid QIMT (598.73 ± 72.16 vs 550.84 ± 29.37 µm), advanced PWV (8.08 ± 1.60 vs 6.24 ± 0.70 m/s), higher stiffness index α (6.21 ± 1.94 vs 3.95 ± 0.78) and β (9.43 ± 3.17 vs 6.38 ± 0.78), higher AP (6.68 ± 2.24 vs 3.64 ± 1.22 mm Hg) and AIx (7.42 ± 2.08 vs 4.69 ± 1.26%), all p < 0.001. Multiple linear regression analysis demonstrated gender was independently associated with carotid structural and elastic parameters.Conclusion:Gender independently impacts carotid structure and function, with females more vulnerable to the progression of arterial aging. Awareness of the gender differences on the risk stratification of carotid artery disease will benefit reliable assessments and specific management recommendations in clinical practice.Advances in knowledge:(1) RFU provides an μm-unit quality IMT measurement and multiple quality arterial stiffness parameters. (2) Gender is an independent determinant in both the arterial structural and elastic aspects, with females of stiffer arteries in low CVD risk individuals.     

Fully Automatic Coronary Calcium Score Software Empowered by Artificial Intelligence Technology: Validation Study Using Three CT Cohorts

ObjectiveThis study aimed to validate a deep learning-based fully automatic calcium scoring (coronary artery calcium [CAC]_auto) system using previously published cardiac computed tomography (CT) cohort data with the manually segmented coronary calcium scoring (CAC_hand) system as the reference standard.Materials and MethodsWe developed the CAC_auto system using 100 co-registered, non-enhanced and contrast-enhanced CT scans. For the validation of the CAC_auto system, three previously published CT cohorts (n = 2985) were chosen to represent different clinical scenarios (i.e., 2647 asymptomatic, 220 symptomatic, 118 valve disease) and four CT models. The performance of the CAC_auto system in detecting coronary calcium was determined. The reliability of the system in measuring the Agatston score as compared with CAC_hand was also evaluated per vessel and per patient using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. The agreement between CAC_auto and CAC_hand based on the cardiovascular risk stratification categories (Agatston score: 0, 1–10, 11–100, 101–400, > 400) was evaluated.ResultsIn 2985 patients, 6218 coronary calcium lesions were identified using CAC_hand. The per-lesion sensitivity and false-positive rate of the CAC_auto system in detecting coronary calcium were 93.3% (5800 of 6218) and 0.11 false-positive lesions per patient, respectively. The CAC_auto system, in measuring the Agatston score, yielded ICCs of 0.99 for all the vessels (left main 0.91, left anterior descending 0.99, left circumflex 0.96, right coronary 0.99). The limits of agreement between CAC_auto and CAC_hand were 1.6 ± 52.2. The linearly weighted kappa value for the Agatston score categorization was 0.94. The main causes of false-positive results were image noise (29.1%, 97/333 lesions), aortic wall calcification (25.5%, 85/333 lesions), and pericardial calcification (24.3%, 81/333 lesions).ConclusionThe atlas-based CAC_auto empowered by deep learning provided accurate calcium score measurement as compared with manual method and risk category classification, which could potentially streamline CAC imaging workflows.     

Chest CT features and progression of patients with coronavirus disease 2019

Objectives:Coronavirus disease 2019 (COVID-19) is a major public health emergency. It poses a grave threat to human life and health. The purpose of the study is to investigate the chest CT findings and progression of the disease observed in COVID-19 patients.Methods:Forty-nine confirmed cases of adult COVID-19 patients with common type, severe and critically severe type were included in this retrospective single-center study. The thin-section chest CT features and progress of the disease were evaluated. The clinical and chest imaging findings of COVID-19 patients with different severity types were compared. The CT severity score and MuLBSTA score (a prediction of mortality risk) were calculated in those patients.Results:Among the 49 patients, 35 patients (71%) were common type and 14 patients (28%) were severe and critically severe type. Nearly all patients (98%) had pure ground-glass opacities (GGO) in CT imaging. Of the severe and critically severe type patients, 86% exhibited GGO with consolidation, in comparison with 54% of the patients with common type. Fibrosis presented in 79% of the severe and critically severe type patients and 43% of the common type patients. The severe and critically severe type patients were significantly more prone to experience five-lobe involvement compared to the common type patients (p = 0.002). The severe and critically severe type patients also had higher CT severity and MuLBSTA scores than the common type patients (5.43 ± 2.38 vs 3.37 ± 2.40, p < 0.001;and 10.21 ± 3.83 vs 4.63 ± 3.43, p < 0.001, respectively). MuLBSTA score was positively correlated with admittance to the intensive care unit (p = 0.005, r = 0.351). Nineteen patients underwent three times CT scan. The interval between first and second CT scan was 4[4,8] days, second and third was 3[2,4] days. There were greater improvements in the third CT follow-up findings compared to the second (p = 0.002).Conclusions:The severe and critically severe type patients often experienced more severe lung lesions, including GGO with consolidation. The CT severity score and MuLBSTA score may be helpful for the assessment of COVID-19 severity and progression.Advances in knowledge:Chest CT has the value of evaluated radiographical features of COVID-19 and allow for dynamic observation of the disease progression. Considering coagulation disorder of COVID-19, MuLBSTA score may need to be updated to increase new understanding of COVID-19.     

CT coronary calcium scoring with tin filtration using iterative beam-hardening calcium correction reconstruction

ObjectivesTo investigate the diagnostic accuracy of CT coronary artery calcium scoring (CACS) with tin pre-filtration (Sn100 kVp) using iterative beam-hardening correction (IBHC) calcium material reconstruction compared to the standard 120 kVp acquisition.BackgroundThird generation dual-source CT (DSCT) CACS with Sn100 kVp acquisition allows significant dose reduction. However, the Sn100 kVp spectrum is harder with lower contrast compared to 120kVp, resulting in lower calcium score values. Sn100 kVp spectral correction using IBHC-based calcium material reconstruction may restore comparable calcium values.MethodsImage data of 62 patients (56% male, age 63.9 ± 9.2years) who underwent a clinically-indicated CACS acquisition using the standard 120 kVp protocol and an additional Sn100 kVp CACS scan as part of a research study were retrospectively analyzed. Datasets of the Sn100 kVp scans were reconstructed using a dedicated spectral IBHC CACS reconstruction to restore the spectral response of 120 kVp spectra. Agatston scores were derived from 120 kVp and IBHC reconstructed Sn100 kVp studies. Pearson’s correlation coefficient was assessed and Agatston score categories and percentile-based risk categorization were compared.ResultsMedian Agatston scores derived from IBHC Sn100 kVp scans and 120 kVp acquisition were 31.7 and 34.1, respectively (p = 0.057). Pearson‘s correlation coefficient showed excellent correlation between the acquisitions (r = 0.99, p < 0.0001). Agatston score categories and percentile-based cardiac risk categories showed excellent agreement (ĸ = 1.00 and ĸ = 0.99), resulting in a low cardiac risk reclassification of 1.6% with the use of IBHC CACS reconstruction. Image noise was 24.9 ± 3.6HU in IBHC Sn100 kVp and 17.1 ± 3.9HU in 120 kVp scans (p < 0.0001). The dose-length-product was 13.2 ± 3.4 mGy cm with IBHC Sn100 kVp and 59.1 ± 22.9 mGy cm with 120 kVp scans (p < 0.0001), resulting in a significantly lower effective radiation dose (0.19 ± 0.07 mSv vs. 0.83 ± 0.33 mSv, p < 0.0001) for IBHC Sn100 kVp scans.ConclusionLow voltage CACS with tin filtration using a dedicated IBHC CACS material reconstruction algorithm shows excellent correlation and agreement with the standard 120 kVp acquisition regarding Agatston score and cardiac risk categorization, while radiation dose is significantly reduced by 75% to the level of a chest x-ray.     

Cone-Beam CT-Guided Percutaneous Transthoracic Needle Lung Biopsy of Juxtaphrenic Lesions: Diagnostic Accuracy and Complications

ObjectiveTo investigate the diagnostic accuracy and complications of cone-beam CT-guided percutaneous transthoracic needle biopsy (PTNB) of juxtaphrenic lesions and identify the risk factors for diagnostic failure and complications.Materials and MethodsIn total, 336 PTNB procedures for lung lesions (mean size ± standard deviation [SD], 4.3 ± 2.3 cm) abutting the diaphragm in 326 patients (189 male and 137 female; mean age ± SD, 65.2 ± 11.4 years) performed between January 2010 and December 2014 were included. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the PTNB procedures for the diagnosis of malignancy were measured based on the intention-to-diagnose principle. The risk factors for diagnostic failures and complications were evaluated using logistic regression analysis.ResultsThe accuracy, sensitivity, specificity, PPV, and NPV were 92.7% (293/316), 91.3% (219/240), 91.4% (74/81), 96.9% (219/226), and 77.9% (74/95), respectively. There were 23 diagnostic failures (7.3%), and lesion sizes ≤ 2 cm (p = 0.045) were the only significant risk factors for diagnostic failure. Complications occurred in 98 cases (29.2%), including 89 cases of pneumothorax (26.5%) and 7 cases of hemoptysis (2.1%). The multivariable analysis showed that old age (> 65 years) (p = 0.002), lesion size of ≤ 2 cm (p = 0.003), emphysema (p = 0.006), and distance from the pleura to the target lesion (> 2 cm) (p = 0.010) were significant risk factors for complications.ConclusionThe diagnostic accuracy of cone-beam CT-guided PTNB of juxtaphrenic lesions for malignancy was fairly high, and the target lesion size was the only significant predictor of diagnostic failure. Complications of cone-beam CT-guided PTNB of juxtaphrenic lesions occurred at a reasonable rate.     

Influence of cone beam CT enhancement filters on diagnosis ability of longitudinal root fractures

Objectives:

To determine whether cone beam CT (CBCT) enhancement filters influence the diagnosis of longitudinal root fractures.

Methods:

40 extracted human posterior teeth were endodontically prepared, and fractures with no separation of fragments were made in 20 teeth of this sample. The teeth were placed in a dry mandible and scanned using a Classic i-CAT® CBCT device (Imaging Sciences International, Inc., Hatfield, PA). Evaluations were performed with and without CBCT filters (Sharpen Mild, Sharpen Super Mild, S9, Sharpen, Sharpen 3 × 3, Angio Sharpen Medium 5 × 5, Angio Sharpen High 5 × 5 and Shadow 3 × 3) by three oral radiologists. Inter- and intraobserver agreement was calculated by the kappa test. Accuracy, sensitivity, specificity and positive and negative predictive values were determined. McNemar test was applied for agreement between all images vs the gold standard and original images vs images with filters (p < 0.05).

Results:

Means of intraobserver agreement ranged from good to excellent. Angio Sharpen Medium 5 × 5 filter obtained the highest positive predictive value (80.0%) and specificity value (76.5%). Angio Sharpen High 5 × 5 filter obtained the highest sensitivity (78.9%) and accuracy (77.5%) value. Negative predictive value was the highest (82.9%) for S9 filter. The McNemar test showed no statistically significant differences between images with and without CBCT filters (p > 0.05).

Conclusions:

Although no statistical differences was observed in the diagnosis of root fractures when using filters, these filters seem to improve diagnostic capacity for longitudinal root fractures. Further in vitro studies with endodontic-treated teeth and research in vivo should be considered.     

Cerebral and tumoral blood flow in adult gliomas: a systematic review of results from magnetic resonance imaging

Objective:Blood flow is the rate of blood movement and relevant to numerous processes, though understudied in gliomas. The aim of this review was to pool blood flow metrics obtained from MRI modalities in adult supratentorial gliomas.Methods:MEDLINE, EMBASE and the Cochrane database were queried 01/01/2000–31/12/2019. Studies measuring blood flow in adult Grade II–IV supratentorial gliomas using dynamic susceptibility contrast (DSC) MRI, dynamic contrast enhanced MRI (DCE-MRI) or arterial spin labelling (ASL) were included. Absolute and relative cerebral blood flow (CBF), peritumoral blood flow and tumoral blood flow (TBF) were reported.Results:34 studies were included with 1415 patients and 1460 scans. The mean age was 52.4 ± 7.3 years. Most patients had glioblastoma (n = 880, 64.6%). The most common imaging modality was ASL (n = 765, 52.4%) followed by DSC (n = 538, 36.8%). Most studies were performed pre-operatively (n = 1268, 86.8%). With increasing glioma grade (II vs IV), TBF increased (70.8 vs 145.5 ml/100 g/min, p < 0.001) and CBF decreased (85.3 vs 49.6 ml/100 g/min, p < 0.001). In Grade IV gliomas, following treatment, CBF increased in ipsilateral (24.9 ± 1.2 vs 26.1 ± 0.0 ml/100 g/min, p < 0.001) and contralateral white matter (25.6 ± 0.2 vs 26.0± 0.0 ml/100 g/min, p < 0.001).Conclusion:Our findings demonstrate that increased mass effect from high-grade gliomas impairs blood flow within the surrounding brain that can improve with surgery.Advances in knowledge:This systematic review demonstrates how mass effect from brain tumours impairs blood flow in the surrounding brain parenchyma that can improve with treatment.     

Low-dose CT urography using deep learning image reconstruction: a prospective study for comparison with conventional CT urography

Objectives:To compare the image quality of low-dose CT urography (LD-CTU) using deep learning image reconstruction (DLIR) with conventional CTU (C-CTU) using adaptive statistical iterative reconstruction (ASIR-V).Methods:This was a prospective, single-institutional study using the excretory phase CTU images for analysis. Patients were assigned to the LD-DLIR group (100kV and automatic mA modulation for noise index (NI) of 23) and C-ASIR-V group (100kV and NI of 10) according to the scan protocols in the excretory phase. Two radiologists independently assessed the overall image quality, artifacts, noise and sharpness of urinary tracts. Additionally, the mean CT attenuation, signal-to-noise ratio (SNR) and contrast-to-noise (CNR) in the urinary tracts were evaluated.Results:26 patients each were included in the LD-DLIR group (10 males and 16 females; mean age: 57.23 years, range: 33–76 years) and C-ASIR-V group (14 males and 12 females; mean age: 60 years, range: 33–77 years). LD-DLIR group used a significantly lower effective radiation dose compared with the C-ASIR-V group (2.01 ± 0.44 mSv vs 6.9 ± 1.46 mSv, p < 0.001). LD-DLIR group showed good overall image quality with average score >4 and was similar to that of the C-ASIR-V group. Both groups had adequate and similar attenuation value, SNR and CNR in most segments of urinary tracts.Conclusion:It is feasibility to provide comparable image quality while reducing 71% radiation dose in low-dose CTU with a deep learning image reconstruction algorithm compared to the conventional CTU with ASIR-V.Advances in knowledge:(1) CT urography with deep learning reconstruction algorithm can reduce the radiation dose by 71% while still maintaining image quality.     

Coronary calcium score and computed tomography coronary angiography in high-risk asymptomatic subjects: assessment of diagnostic accuracy and prevalence of non-obstructive coronary artery disease

Objectives

The aim of the study was to compare the coronary artery calcium score (CACS) and computed tomography coronary angiography (CTCA) for the assessment of non-obstructive/obstructive coronary artery disease (CAD) in high-risk asymptomatic subjects.

Methods

Two hundred and thirteen consecutive asymptomatic subjects (113 male; mean age 53.6?±?12.4 years) with more than one risk factor and an inconclusive or unfeasible non-invasive stress test result underwent CACS and CTCA in an outpatient setting. All patients underwent conventional coronary angiography (CAG). Data from CACS (threshold for positive image: Agatston score 1/100/1,000) and CTCA were compared with CAG regarding the degree of CAD (non-obstructive/obstructive; </≥50% lumen reduction).

Results

The mean calcium score was 151?±?403 and the prevalence of obstructive CAD was 17% (8% one-vessel and 10% two-vessel disease). Per-patient sensitivity, specificity, positive and negative predictive values of CACS were: 97%, 75%, 45%, and 100%, respectively (Agatston?≥1); 73%, 90%, 60%, and 94%, respectively (Agatston?≥100); 30%, 98%, 79%, and 87%, respectively (Agatston?≥1,000). Per-patient values for CTCA were 100%, 98%, 97%, and 100%, respectively (p?<?0.05). CTCA detected 65% prevalence of all CAD (48% non-obstructive), while CACS detected 37% prevalence of all CAD (21% non-obstructive) (p?<?0.05).

Conclusion

CACS proved inadequate for the detection of obstructive and non-obstructive CAD compared with CTCA. CTCA has a high diagnostic accuracy for the detection of non-obstructive and obstructive CAD in high-risk asymptomatic patients with inconclusive or unfeasible stress test results.     

Accessory spleen-like masses in oncology patients: Are they always benign?

AIM: To assess retrospectively the significance of accessory spleen-like mass (ASLM) in oncology patients undergoing positron emission tomography/computed tomography (PET/CT).METHODS: The results of PET/CT of 913 patients (278 lymphoma; 635 solid tumors) were reviewed. The number, size, location and attenuation of all ASLMs, and spleen attenuation, were recorded. ASLM fluorodeoxyglucose uptake was graded as normal (less than or equal to that in the liver) or representative of malignancy (more than in the liver). Follow-up PET/CT in patients with ASLM was reviewed when available. ASLM size and attenuation for spleen and ASLM were compared by unpaired Student’s t test. The χ² and Fisher’s exact tests were used to compare ASLM frequency and uptake for lymphomatous and solid tumors, respectively.RESULTS: ASLM frequency was 14.8%, with 152 ASLMs found in 135 patients. Mean attenuation was lower in ASLM compared with spleen by enhanced and non-enhanced CT (80.7 ± 20.4 HU vs 92.0 ± 14.4 HU, P < 0.0011 and 42.3 ± 9.0 HU vs 51.5 ± 6.3 HU, P < 0.0001, respectively). ASLM incidence was higher in lymphoma patients (56/278, 20.1%) than in those with solid tumors (56/278, 20.1% vs 79/635, 12.4%, P = 0.0036). Pathological uptake was found in four (7.1%) lymphoma patients but not in any patients with a solid tumor (P = 0.028) and it upstaged one patient with lymphoma. Follow-up PET/CT within 3-16 mo was available in 54% of patients with ASLM. Lesion regression was noted in all four pathological ASLMs on follow-up PET/CT after chemotherapy.CONCLUSION: In patients with lymphoma, ASLM can represent malignancy, and thus further characterization with PET/CT might be warranted. Patients with neoplasia other than ASLM can be confidently diagnosed with accessory spleen.     

Imaging diagnosis of basal ganglia germ cell tumors: subtype features subtype imaging features of GCTs

Objectives:To evaluate the subtype imaging features of basal ganglia germ cell tumors (GCTs).Methods:Clinical and imaging data of 33 basal ganglia GCTs were retrospectively analyzed, including 17 germinomas and 16 mixed germ cell tumors (MGCTs).Results:The cyst/mass ratio of germinomas (0.53 ± 0.32) was higher than that of MGCTs (0.28 ± 0.19, p = 0.030). CT density of the solid part of germinomas (41.47 ± 5.22 Hu) was significantly higher than that of MGCTs (33.64 ± 3.75 Hu, p < 0.001), while apparent diffusion coefficients (ADC, ×^10-3 mm²/s) value of the solid part was significantly lower in geminomas (0.86 ± 0.27 ×^10-3 mm²/s) than in MGCTs (1.42 ± 0.39 ×^10-3 mm²/s, p < 0.001). MGCTs were more common with intratumoral hemorrhage (68.75% vs 11.76%, p = 0.01), T1 hyperintense foci (68.75% vs 5.88%, p < 0.001) and calcification (64.29% vs 20.00%, p = 0.025) than germinomas. There was no significant difference in internal capsule involvement between the two subtypes (p = 0.303), but Wallerian degeneration was more common in germinomas than in MGCTs (70.59% vs 25.00%, p = 0.015).Conclusion:The subtypes of GCT have different imaging features. Tumoral cystic-solidity, heterogeneity, ADC value, CT density, and Wallerian degeneration are helpful to differentiate germinomas and MGCTs in basal ganglia.Advances in knowledge:The subtypes of GCT have different histological characteristics, leading to various imaging findings. The imaging features of GCT subtypes in basal ganglia may aid clinical diagnosis and treatment.     

Adaptive Statistical Iterative Reconstruction-Applied Ultra-Low-Dose CT with Radiography-Comparable Radiation Dose: Usefulness for Lung Nodule Detection

Objective

To assess the performance of adaptive statistical iterative reconstruction (ASIR)-applied ultra-low-dose CT (ULDCT) in detecting small lung nodules.

Materials and Methods

Thirty patients underwent both ULDCT and standard dose CT (SCT). After determining the reference standard nodules, five observers, blinded to the reference standard reading results, independently evaluated SCT and both subsets of ASIR- and filtered back projection (FBP)-driven ULDCT images. Data assessed by observers were compared statistically.

Results

Converted effective doses in SCT and ULDCT were 2.81 ± 0.92 and 0.17 ± 0.02 mSv, respectively. A total of 114 lung nodules were detected on SCT as a standard reference. There was no statistically significant difference in sensitivity between ASIR-driven ULDCT and SCT for three out of the five observers (p = 0.678, 0.735, < 0.01, 0.038, and < 0.868 for observers 1, 2, 3, 4, and 5, respectively). The sensitivity of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT in three out of the five observers (p < 0.01 for three observers, and p = 0.064 and 0.146 for two observers). In jackknife alternative free-response receiver operating characteristic analysis, the mean values of figure-of-merit (FOM) for FBP, ASIR-driven ULDCT, and SCT were 0.682, 0.772, and 0.821, respectively, and there were no significant differences in FOM values between ASIR-driven ULDCT and SCT (p = 0.11), but the FOM value of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT and SCT (p = 0.01 and 0.00).

Conclusion

Adaptive statistical iterative reconstruction-driven ULDCT delivering a radiation dose of only 0.17 mSv offers acceptable sensitivity in nodule detection compared with SCT and has better performance than FBP-driven ULDCT.     

Reliability of respiratory-triggered two-dimensional cine k-adaptive-t-autocalibrating reconstruction for Cartesian sampling for the assessment of biventricular volume and function in patients with repaired tetralogy of Fallot

Objective:To compare left ventricular (LV) and right ventricular (RV) volume, function, and image quality of a respiratory-triggered two-dimensional (2D)-cine k-adaptive-t-autocalibrating reconstruction for Cartesian sampling (2D kat-ARC) with those of the standard reference, namely, breath-hold 2D balanced steady-state free precession (2D SSFP), in patients with repaired tetralogy of Fallot (TOF).Methods:30 patients (14 males, mean age 32.2 ± 13.9 years) underwent cardiac magnetic resonance, and 2D kat-ARC and 2D SSFP images were acquired on short-axis view. Biventricular end-diastolic volume (EDV) and end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass (LVM) were analysed.Results:The 2D kat-ARC had significantly shorter scan time (35.2 ± 9.1 s vs 80.4 ± 16.7 s; p < 0.0001). Despite an analysis of image quality showed significant impairment using 2D kat-ARC compared to 2D SSFP cine (p < 0.0001), the two sequences demonstrated no significant difference in terms of biventricular EDV, LVESV, LVSV, LVEF, and LVM. However, the RVESV was overestimated for 2D kat-ARC compared with that for 2D SSFP (73.8 ± 43.2 ml vs 70.3 ± 44.5 ml, p = 0.0002) and the RVSV and RVEF were underestimated (RVSV = 46.2±20.5 ml vs 49.4 ± 20.4 ml, p = 0.0024; RVEF = 40.2±12.7% vs. 43.5±14.0%, p = 0.0002).Conclusion:Respiratory-triggered 2D kat-ARC cine is a reliable technique that could be used in the evaluation of LV volumes and function.Advances in knowledge:2D cine kat-ARC is a reliable technique for the assessment LV volume and function in patients with repaired TOF.     

Correlation analysis of dual-energy CT iodine maps with quantitative pulmonary perfusion MRI

AIM:To correlate dual-energy computed tomography(DECT) pulmonary angiography derived iodine maps with parameter maps of quantitative pulmonary perfusion magnetic resonance imaging(MRI).METHODS:Eighteen patients with pulmonary perfusion defects detected on DECT derived iodine maps were included in this prospective study and additionally underwent time-resolved contrast-enhanced pulmonary MRI [dynamic contrast enhanced(DCE)-MRI].DCE-MRI data were quantitatively analyzed using a pixel-by-pixel deconvolution analysis calculating regional pulmonary blood flow(PBF),pulmonary blood volume(PBV) and mean transit time(MTT) in visually normal lung parenchyma and perfusion defects.Perfusion parameterswere correlated to mean attenuation values of normal lung and perfusion defects on DECT iodine maps.Two readers rated the concordance of perfusion defects in a visual analysis using a 5-point Likert-scale(1 = no correlation,5 = excellent correlation).RESULTS:In visually normal pulmonary tissue mean DECT and MRI values were:22.6 ± 8.3 Hounsfield units(HU);PBF:58.8 ± 36.0 mL/100 mL per minute;PBV:16.6 ± 8.5 mL;MTT:17.1 ± 10.3 s.In areas with restricted perfusion mean DECT and MRI values were:4.0 ± 3.9 HU;PBF:10.3 ± 5.5 mL/100 mL per minute,PBV:5 ± 4 mL,MTT:21.6 ± 14.0 s.The differences between visually normal parenchyma and areas of restricted perfusion were statistically significant for PBF,PBV and DECT(P < 0.0001).No linear correlation was found between MRI perfusion parameters and attenuation values of DECT iodine maps(PBF:r = 0.35,P = 0.15;PBV:r = 0.34,P = 0.16;MTT:r = 0.41,P = 0.08).Visual analysis revealed a moderate correlation between perfusion defects on DECT iodine maps and the parameter maps of DCE-MRI(mean score 3.6,k 0.45).CONCLUSION:There is a moderate visual but not statistically significant correlation between DECT iodine maps and perfusion parameter maps of DCE-MRI.     

Feasibility study of computed vs measured high b-value (1400 s/mm2) diffusion-weighted MR images of the prostate

AIM: To evaluate the impact of computed b = 1400 s/mm² (C-b1400) vs measured b = 1400 s/mm² (M-b1400) diffusion-weighted images (DWI) on lesion detection rate, image quality and quality of lesion demarcation using a modern 3T-MR system based on a small-field-of-view sequence (sFOV).METHODS: Thirty patients (PSA: 9.5 ± 8.7 ng/mL; 68 ± 12 years) referred for magnetic resonance imaging (MRI) of the prostate were enrolled in this study. All measurements were performed on a 3T MR system. For DWI, a single-shot EPI diffusion sequence (b = 0, 100, 400, 800 s/mm²) was utilized. C-b1400 was calculated voxelwise from the ADC and diffusion images. Additionally, M-b1400 was acquired for evaluation and comparison. Lesion detection rate and maximum lesion diameters were obtained and compared. Image quality and quality of lesion demarcation were rated according to a 5-point Likert-type scale. Ratios of lesion-to-bladder as well as prostate-to-bladder signal intensity (SI) were calculated to estimate the signal-to-noise-ratio (SNR).RESULTS: Twenty-four lesions were detected on M-b1400 images and compared to C-b1400 images. C-b1400 detected three additional cancer suspicious lesions. Overall image quality was rated significantly better and SI ratios were significantly higher on C-b1400 (2.3 ± 0.8 vs 3.1 ± 1.0, P < 0.001; 5.6 ± 1.8 vs 2.8 ± 0.9, P < 0.001). Comparison of lesion size showed no significant differences between C- and M-b1400 (P = 0.22).CONCLUSION: Combination of a high b-value extrapolation and sFOV may contribute to increase diagnostic accuracy of DWI without an increase of acquisition time, which may be useful to guide targeted prostate biopsies and to improve quality of multiparametric MRI (mMRI) especially under economical aspects in a private practice setting.     

Head and neck single- and dual-energy CT: differences in radiation dose and image quality of 2nd and 3rd generation dual-source CT

Objectives:To compare radiation dose and image quality of single-energy (SECT) and dual-energy (DECT) head and neck CT examinations performed with second- and third-generation dual-source CT (DSCT) in matched patient cohorts.Methods:200 patients (mean age 55.1 ± 16.9 years) who underwent venous phase head and neck CT with a vendor-preset protocol were retrospectively divided into four equal groups (n = 50) matched by gender and BMI: second (Group A, SECT, 100-kV; Group B, DECT, 80/Sn140-kV), and third-generation DSCT (Group C, SECT, 100-kV; Group D, DECT, 90/Sn150-kV). Assessment of radiation dose was performed for an average scan length of 27 cm. Contrast-to-noise ratio measurements and dose-independent figure-of-merit calculations of the submandibular gland, thyroid, internal jugular vein, and common carotid artery were analyzed quantitatively. Qualitative image parameters were evaluated regarding overall image quality, artifacts and reader confidence using 5-point Likert scales.Results:Effective radiation dose (ED) was not significantly different between SECT and DECT acquisition for each scanner generation (p = 0.10). Significantly lower effective radiation dose (p < 0.01) values were observed for third-generation DSCT groups C (1.1 ± 0.2 mSv) and D (1.0 ± 0.3 mSv) compared to second-generation DSCT groups A (1.8 ± 0.1 mSv) and B (1.6 ± 0.2 mSv). Figure-of-merit/contrast-to-noise ratio analysis revealed superior results for third-generation DECT Group D compared to all other groups. Qualitative image parameters showed non-significant differences between all groups (p > 0.06).Conclusion:Contrast-enhanced head and neck DECT can be performed with second- and third-generation DSCT systems without radiation penalty or impaired image quality compared with SECT, while third-generation DSCT is the most dose efficient acquisition method.Advances in knowledge:Differences in radiation dose between SECT and DECT of the dose-vulnerable head and neck region using DSCT systems have not been evaluated so far. Therefore, this study directly compares radiation dose and image quality of standard SECT and DECT protocols of second- and third-generation DSCT platforms.