Tissue characterization of acute lesions during cardiac magnetic resonance-guided ablation of cavo-tricuspid isthmus-dependent atrial flutter: a feasibility study

AIMS

To characterize acute lesions during cardiac magnetic resonance (CMR)-guided radiofrequency (RF) ablation of cavo-tricuspid isthmus (CTI)-dependent atrial flutter by combining T2-weighted imaging (T2WI), T1 mapping, first-pass perfusion, and late gadolinium enhancement (LGE) imaging. CMR-guided catheter ablation offers a unique opportunity to investigate acute ablation lesions. Until present, studies only used T2WI and LGE CMR to assess acute lesions.

METHODS AND RESULTS

Fifteen patients with CTI-dependent atrial flutter scheduled for CMR-guided RF ablation were prospectively enrolled. Directly after achieving bidirectional block of the CTI line, CMR imaging was performed using: T2WI (n = 15), T1 mapping (n = 10), first-pass perfusion (n = 12), and LGE (n = 12) imaging. In case of acute reconnection, additional RF ablation was performed. In all patients, T2WI demonstrated oedema in the ablation region. Right atrial T1 mapping was feasible and could be analysed with a high inter-observer agreement (r = 0.931, ICC 0.921). The increase in T1 values post-ablation was significantly lower in regions showing acute reconnection compared with regions without reconnection [37 ± 90 ms vs. 115 ± 69 ms (P = 0.014), and 3.9 ± 9.0% vs. 11.1 ± 6.8% (P = 0.022)]. Perfusion defects were present in 12/12 patients. The LGE images demonstrated hyper-enhancement with a central area of hypo-enhancement in 12/12 patients.

CONCLUSION

Tissue characterization of acute lesions during CMR-guided CTI-dependent atrial flutter ablation demonstrates oedema, perfusion defects, and necrosis with a core of microvascular damage. Right atrial T1 mapping is feasible, and may identify regions of acute reconnection that require additional RF ablation.

Flow patterns in ascending aortic aneurysms: Determining the role of hypertension using phase contrast magnetic resonance and computational fluid dynamics

Thoracic aortic aneurysm (TAA) is a local dilation of the thoracic aorta. Although universally used, aneurysm diameter alone is a poor predictor of major complications such as rupture. There is a need for better biomarkers for risk assessment that also reflect the aberrant flow patterns found in TAAs. Furthermore, hypertension is often present in TAA patients and may play a role in progression of aneurysm. The exact relation between TAAs and hypertension is poorly understood. This study aims to create a numerical model of hypertension in the aorta by using computational fluid dynamics. First, a normotensive state was simulated in which flow and resistance were kept unaltered. Second, a hypertensive state was modeled in which blood inflow was increased by 30%. Third, a hypertensive state was modeled in which the proximal and peripheral resistances and capacitance parameters from the three-element Windkessel boundary condition were adjusted to mimic an increase in resistance of the rest of the cardiovascular system. One patient with degenerative TAA and one healthy control were successfully simulated at hypertensive states and were extensively analyzed. Furthermore, three additional TAA patients and controls were simulated to validate our method. Hemodynamic variables such as wall shear stress, oscillatory shear index, endothelial cell activation potential (ECAP), vorticity and helicity were studied to gain more insight on the effects of hypertension on flow patterns in TAAs. By comparing a TAA patient and a control at normotensive state at peak-systole, helicity and vorticity were found to be lower in the TAA patient throughout the entire domain. No major changes in flow and flow derived quantities were observed for the TAA patient and control when resistance was increased. When flow rate was increased, regions with high ECAP values were found to reduce in TAA patients in the aneurysm region which could reduce the risk of thrombogenesis. Thus, it may be important to assess cardiac output in patients with TAA.

Altered biodistribution of [68Ga]Ga-DOTA-TOC during somatostatin analogue treatment

PURPOSE

The need for an interval between the administration of long-acting Somatostatin Receptor Analogues (SSA) and the [68Ga]Ga-DOTA-TATE PET has been questioned based on recent literature in the new EANM guidelines. Here an earlier studies showed that SSA injection immediately before SSTR PET had minimal effect on normal organ and tumor uptake (1). However, data are scarce and there are (small) differences between [68Ga]Ga-DOTA-TATE and [68Ga]Ga-DOTA-TOC binding affinity, and it remains unknown whether these findings can be directly translated to scans with [68Ga]Ga-DOTA-TOC as well. The purpose of this study was to assess the effect of SSA use on the biodistribution in a subsequent [68Ga]Ga-DOTA-TOC PET/CT and compare this intra-individually across several cycles of SSA treatments.

METHODS

Retrospectively, 35 patients with NENs were included. [68Ga]Ga-DOTA-TOC PET at staging and after the 1st and 2nd cycle of SSA were included. SUVmean and SUVmax of blood, visceral organs, primary tumor and two metastases were determined. Also, the interval between SSA therapy and the PET scan was registered.

RESULTS

Treatment with SSA resulted in a significantly higher bloodpool activity and lower visceral tracer uptake. This effect was maintained after a 2nd cycle of SSA therapy. Furthermore, there was an inverse relationship between bloodpool tracer availability and visceral tracer binding and a positive correlation between bloodpool tracer availability and primary tumor tracer uptake. With an interval of up to 5 days, there was a significantly higher bloodpool activity than at longer intervals.

CONCLUSION

Absolute comparison of the SUV on [68Ga]Ga-DOTA-TOC PET should be done with caution as the altered biodistribution of the tracer after SSA treatment should be taken into account. We recommend not to perform a scan within the first 5 days after the injection of lanreotide.

Contrast-enhanced breast imaging: Current status and future challenges

BACKGROUND

Contrast-enhanced breast MRI and recently also contrast-enhanced mammography (CEM) are available for breast imaging. The aim of the current overview is to explore existing evidence and ongoing challenges of contrast-enhanced breast imaging.

METHODS

This narrative provides an introduction to the contrast-enhanced breast imaging modalities breast MRI and CEM. Underlying principle, techniques and BI-RADS reporting of both techniques are described and compared, and the following indications and ongoing challenges are discussed: problem-solving, high-risk screening, supplemental screening in women with extremely dense breast tissue, breast implants, neoadjuvant systemic therapy (NST) response monitoring, MRI-guided and CEM- guided biopsy.

RESULTS

Technique and reporting for breast MRI are standardised, for the newer CEM standardisation is in progress. Similarly, compared to other modalities, breast MRI is well established as superior for problem-solving, screening women at high risk, screening women with extremely dense breast tissue or with implants; and for monitoring response to NST. Furthermore, MRI-guided biopsy is a reliable technique with low long-term false negative rates. For CEM, data is as yet either absent or limited, but existing results in these settings are promising.

CONCLUSION

Contrast-enhanced breast imaging achieves highest diagnostic performance and should be considered essential. Of the two contrast-enhanced modalities, evidence of breast MRI superiority is ample, and preliminary results on CEM are promising, yet CEM warrants further study.

The use of novel 3D dark-blood late gadolinium enhancement MRI to determine the optimal threshold for atrial scar after pulmonary vein isolation ablation

Background

Dark-blood late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is proved to be superior to bright-blood LGE MRI in localising subtle subendocardial scar in the ventricles, because of improved contrast between myocardial scar and blood. However, dark-blood LGE MRI has not yet been applied to identify atrial scar in the left atrium (LA) and therefore its threshold to determine scar is unknown.

Purpose

To determine the optimal intensity threshold for 3D dark-blood LGE MRI for atrial ablation scar after pulmonary vein isolation (PVI)

Methods

Twelve re-do PVI patients with symptomatic atrial fibrillation (AF) who underwent pre-procedural 3D dark-blood LGE MRI were included. The image intensity ratio (IIR = myocardial intensity normalized to the blood pool) from the LGE MRI were calculated using ADAS-AF. High-density bipolar voltages (BiV) maps were recorded during sinus rhythm prior to ablation. All BiV locations ≤5 mm from the ADAS LA anatomy were compared with the corresponding IIR, using custom-made software in MATLAB. To achieve an equal ratio between scar (BiV ≤0.15 mV) and non-scar (BiV >0.15 mV) for each patient, non-scar pairs were randomly resampled to the same number as scar pairs. This was repeated 10 times and for every random selection, receiver operating characteristics (ROC) analysis was performed to determine the optimal IIR threshold (provided by the Youden's index) for scar defined as BiV <0.15 mV (Figure 1). All IIR thresholds and areas under the curve were averaged to determine the overall performance and optimal IIR threshold.

Results

Of the 12 included patients, 8 had prior cryo PVI, 2 radiofrequency PVI, and 2 surgical/hybrid AF ablation. ROC curve analysis estimated the average optimal threshold for predicting BiV <0.15 mV to be an IIR of 1.106, with a mean area under the curve (AUC) of 0.73 (Figure 1). Figure 2 shows two examples of the IIR map (A), BiV map (B), and the correspondence map (C) providing information on spatial agreement between IIR and BiV. This individual qualitative assessment provides insight into the spatial variation between techniques and may facilitate future studies on the pathophysiological understanding of atrial ablation scarring.

Conclusion

This is the first study to use the novel 3D dark-blood whole heart LGE MRI to evaluate LA ablation scar after PVI. Based on the ROC analyses, an IIR of 1.106 is the optimal threshold for atrial ablation scar, defined as high density bipolar voltage <0.15 mV.

Funding Acknowledgement

Type of funding sources: None.

Direct pre- and post-ablation cardiac magnetic resonance imaging of tissue characteristics in patients with typical atrial flutter

Funding Acknowledgements

Type of funding sources: None.

Background

Real-time cardiac magnetic resonance (CMR) imaging as guidance in electrophysiology (EP) procedures enables a detailed overview of the anatomy of the heart and surrounding structures, active and passive catheter tracking, and real-time visualisation of ablation lesions throughout the ablation procedure, without using fluoroscopy.

Purpose

To evaluate ablation induced changes in tissue characteristics of the cavotricuspid isthmus (CTI), directly following typical atrial flutter ablation in an interventional cardiac magnetic resonance (iCMR) suite.

Methods

Nine patients with symptomatic typical atrial flutter were referred for CTI ablation in an iCMR suite. Procedures were performed using a 1.5T MRI scanner. Pre-ablation imaging included T2-weighted edema imaging in the right anterior oblique (RAO) and transversal view. During the ablation procedure, CMR imaging facilitated active tracking and real-time navigation of both diagnostic and ablation catheters, as well as visualisation of the ablated tissue. Post-ablation imaging to evaluate the target tissue again included T2-weighted edema imaging as well as dark-blood late gadolinium enhancement (LGE) imaging. Data regarding post-ablation imaging findings, ablation outcome, and complications were collected for all patients. All patients provided written informed consent.

Results

In eight of the nine patients, T2-weighted imaging was successfully performed pre- and post-ablation, which identified myocardial edema at the CTI ablation line in all patients (Figure 1A-B). Due to time restraints, post-ablation LGE imaging was performed in five patients, which showed pathological signal intensity at the level of the CTI in all five patients (Figure 1C). Bidirectional block of the CTI was confirmed by differential pacing in eight patients. No complications occurred during or immediately after the procedures. In one patient, the registration of intracardiac electrograms was not possible due to technical problems and the patient was transferred to a conventional EP lab to complete the ablation following our predefined bailout procedure.

Conclusion

Real-time CMR guided CTI ablation in patients with typical atrial flutter is safe and successful. CMR enables accurate visualisation of the CTI line and provides immediate post-ablation evaluation of tissue characteristics at the ablation target location.

Figure 1. T2-weighted edema cardiac magnetic resonance (CMR) imaging in the right anterior oblique (RAO) view acquired pre- (A) and post-ablation (B) during interventional CMR ablation therapy. Late gadolinium enhancement (LGE) CMR in the RAO view post-ablation (C) of the same patient. The blue arrowheads indicate the cavotricuspid isthmus (CTI) line. High signal intensity at the level of CTI is observed post-ablation on both T2-weighted (indicating edema) and LGE (indicating cell membrane rupture) images.

First clinical experience with cardiac magnetic resonance guided typical atrial flutter ablation with the integration of active catheter tracking and electro-anatomical mapping

Funding Acknowledgements

Type of funding sources: None.

Background

In our university hospital, we previously implemented cardiac magnetic resonance (CMR) guided typical atrial flutter ablation in a pre-existing MRI suite which was transformed into an interventional cardiac MRI (iCMR) suite.

Purpose

To describe our first clinical experience with integration of active catheter tracking and dedicated electro-anatomical mapping (EAM) system for the treatment of typical atrial flutter in a transformed pre-existing MRI suite.

Methods

Between February 2021 and December 2021, all consecutive patients planned for CMR guided typical atrial flutter ablation were included in this analysis. The procedure was performed under general anaesthesia. Feasibility and safety of active catheter tracking and the integration with a dedicated EAM was evaluated. All patients provided written informed consent.

Results

In total, nine patients underwent CMR guided atrial flutter ablation. Procedural characteristics are presented in Table 1. In all patients, both active catheter tracking and the integration with EAM were performed successfully. Bidirectional cavo-tricuspid isthmus block was achieved in eight out of nine patients and confirmed by differential pacing using intracardiac electrograms and EAM. In one of these eight patients, the registration of intracardiac electrograms was not possible due to technical problems and the patient was transferred to a conventional electrophysiology lab to complete the ablation following our predefined bailout procedure. Seven out of nine patients were in sinus rhythm at the start of the procedure, one in nodal rhythm with atrial bigeminy, one patient required electrical cardioversion for atrial fibrillation prior to the procedure. No periprocedural complications occurred.

Conclusion

CMR guided typical atrial flutter ablation in a transformed pre-existing MRI suite using active catheter tracking and a dedicated EAM system is feasible and safe based on this small population. It allows for detailed visualisation of catheters and individual patients anatomy. Further studies in larger patient populations are required to evaluate whether iCMR is cost effective and can improve clinical outcome of typical atrial flutter ablation and other arrhythmias.

Concealed Coronary Atherosclerosis In Idiopathic Paroxysmal Atrial Fibrillation is Associated with Imminent Cardiovascular Diseases

Background

Previous research showed a significant difference in the presence of subclinical coronary artery disease (CAD) on cardiac CT angiography (CTA) between patients with idiopathic paroxysmal atrial fibrillation (iAF) versus a matched sinus rhythm population (iSR). Here we present 5-year follow-up data and the consequences of subclinical CAD on baseline CTA on the development of cardiovascular disease in iAF.

Methods

In 99 iAF patients (who underwent CTA as part of work-up for pulmonary vein isolation) and 221 matched iSR controls (who underwent CTA for CAD assessment), the incidence of hypertension, diabetes and major cardiovascular events (MACCE) during follow-up was obtained. Multivariable Cox regression analysis was used to reveal predictors of incident cardiovascular disease in the iAF group.

Results

During a follow-up of 68±11 months, over one third of patients developed cardiovascular disease, with no difference between iAF and iSR (log-rank p=0.56), and comparable low rates of MACCE (4.0% vs 5.0%,p=0.71). Within the iAF group, age (HR1.12(1.03-1.20);p=0.006), left atrial diameter (HR1.16(1.03-1.31);p=0.01), Segment Involvement Score (total number of coronary segments with atherosclerotic plaque; HR1.43(1.09-1.89);p=0.01) and the number of calcified plaques on CTA (HR0.53(0.30-0.92);p=0.01) were independent predictors of incident cardiovascular disease.

Conclusions

Subclinical coronary disease on CTA may be useful to identify the subset of patients with iAF that harbour concealed cardiovascular risk factors and need intensive clinical follow-up to ensure timely initiation of appropriate therapy once CV disease develops, including anticoagulation and vascular prophylactic therapy.

Determining the optimal interval for imaging surveillance of ascending aortic aneurysms

Background

Cardiovascular guidelines recommend (bi-)annual computed tomography (CT) or magnetic resonance imaging (MRI) for surveillance of the diameter of thoracic aortic aneurysms (TAAs). However, no previous study has demonstrated the necessity for this approach. The current study aims to provide patient-specific intervals for imaging follow-up of non-syndromic TAAs.

Methods

A total of 332 patients with non-syndromic ascending aortic aneurysms were followed over a median period of 6.7 years. Diameters were assessed using all available imaging techniques (echocardiography, CT and MRI). Growth rates were calculated from the differences between the first and last examinations. The diagnostic accuracy of follow-up protocols was calculated as the percentage of subjects requiring pre-emptive surgery in whom timely identification would have occurred.

Results

The mean growth rate in our population was 0.2 ± 0.4 mm/year. The highest recorded growth rate was 2.0 mm/year, while 40.6% of patients showed no diameter expansion during follow-up. Females exhibited significantly higher growth rates than men (0.3 ± 0.5 vs 0.2 ± 0.4 mm/year, p = 0.007). Conversely, a bicuspid aortic valve was not associated with more rapid aortic growth. The optimal imaging protocol comprises triennial imaging of aneurysms 40–49 mm in diameter and yearly imaging of those measuring 50–54 mm. This strategy is as accurate as annual follow-up, but reduces the number of imaging examinations by 29.9%.

Conclusions

In our population of patients with non-syndromic TAAs, we found aneurysm growth rates to be lower than those previously reported. Yearly imaging does not lead to changes in the management of small aneurysms. Thus, lower imaging frequencies might be a good alternative approach.

The performance of non-ECG gated chest CT for cardiac assessment - The cardiac pathologies in chest CT (CaPaCT) study

PURPOSE

Evaluating the prevalence of CAD on non-ECG gated chest CTs, image quality (IQ) and the clinical performance of the CAD-RADS classification for predicting cardiovascular events (CVE).

METHODS

215 consecutive patients referred for chest CTs between May 2016 and March 2018 were included (3rd-generation DSCT) using non-ECG gated acquisitions with automated tube voltage selection (110kV_qual.ref/40mAs_qual.ref), pitch 2.65-3.0 and individualized contrast media injection protocols. Dedicated cardiac post-processing reconstructions (0.6 mm/0.4 mm/Kernel Bv36) were added to standard chest reconstructions. Two independent cardiac radiologists performed a 3-step analysis. In case of discrepancy, a third reader gave the final decision. Step 1: visual presence of calcifications; 2: scans with calcifications assessed for IQ using a 5-point Likert scale (poor/sufficient/moderate/good/excellent); 3: stenosis severity was analysed in detail (if Likert sufficient-excellent using CAD-RADS). Electronic patient files were checked to see if pathology was previously mentioned (incidental) and whether patients developed an CVE during follow-up.

RESULTS

1: Calcifications were present in 156/215 cases (72.6 %), 74 of these were incidental. 2: In 68/156 (43.6 %) patients with calcifications IQ was rated sufficient-excellent. 3: CAD-RADS≥3 was seen in 39/68 patients (57.4 %), 12 times (30.8 %) findings were incidental. During follow-up (median 16 [0-35] months), 7/39 (18 %) patients with CAD-RADS≥3 developed a CVE. 17 patients died during follow-up.

CONCLUSION

Coronary calcification on non ECG-gated chest CTs was detected in 72.6 % of patients, cardiac assessment was feasible in nearly half of these patients. Only patients with a CAD-RADS≥3 developed CVE, therefore the CAD-RADS may help identify and guide patients at risk of future CVE.

Impact on clinical practice of updated guidelines on iodinated contrast material: CINART

Objective

Guidelines on safe use of iodinated contrast material recommend intravenous prophylactic hydration to prevent post-contrast adverse (renal) effects. Recently, guidelines have been updated and standard prophylaxis is no longer recommended for the majority of patients. The current study aims to evaluate the consequences for clinical practice of the updated guidelines in terms of complications, hospitalisations, and costs.

Methods

The Contrast-Induced Nephropathy After Reduction of the prophylaxis Threshold (CINART) project is a retrospective observational study. All elective procedures with intravascular iodinated contrast administration at Maastricht University Medical Centre (UMC+) in patients aged > 18 years, formerly eligible for prophylaxis (eGFR 30–44 ml/min/1.73 m² or eGFR 45–59 ml/min/1.73 m² in combination with diabetes or > 1 predefined risk factor), and currently eligible for prophylaxis (eGFR < 30 ml/min/1.73 m²) were included. Data were used to calculate relative reductions in complications, hospitalisations, and costs associated with standard prophylactic intravenous hydration. CINART is registered with Clinicaltrials.gov: NCT03227835.

Results

Between July 1, 2017, and July 1, 2018, 1992 elective procedures with intravascular iodinated contrast in patients formerly and currently eligible for prophylaxis were identified: 1808 in patients formerly eligible for prophylaxis and 184 in patients currently eligible for prophylaxis. At Maastricht UMC+, guideline updates led to large relative reductions in numbers of complications of prophylaxis (e.g. symptomatic heart failure; − 89%), extra hospitalisations (− 93%), and costs (− 91%).

Conclusion

Guideline updates have had a demonstrable impact on daily clinical practice benefiting patient, hospital, and health care budgets. Clinical practice varies between institutions and countries; therefore, a local estimation model is provided with which local impact on costs, hospitalisations, and complications can be calculated.

Key Points

• Clinical practice guidelines recommend prophylactic intravenous hydration to prevent post-contrast adverse outcomes such as contrast-induced acute kidney injury.

• Clinical practice guidelines have recently been updated, and standard prophylaxis is no longer recommended for the majority of patients.

• The guideline updates have a large impact on daily clinical practice: relative reductions at Maastricht UMC+ were − 89% prophylaxis complications, − 93% hospitalisations, and − 91% costs, and similar reductions are expected for Dutch and adherent European medical centres.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-06719-7) contains supplementary material, which is available to authorized users.

Rapid Access to Contrast-Enhanced spectral mammogRaphy in women recalled from breast cancer screening: the RACER trial study design

BACKGROUND

In the Dutch breast cancer screening program, women recalled with a BI-RADS 0 score are referred for additional imaging, while those with BI-RADS 4/5 scores are also directed to an outpatient breast clinic. Approximately six out of ten women are recalled without being diagnosed with a malignancy. However, these recalls require additional imaging and doctor visits, which result in patient anxiety and increased health care costs. Conventional types of imaging used for additional imaging are full-field digital mammography and tomosynthesis. Contrast-enhanced spectral mammography has proved to have higher sensitivity and specificity than conventional imaging in women recalled from screening. Therefore, the aim is to study if CESM instead of conventional imaging is a more accurate, patient-friendly, and cost-effective strategy in the work-up of women recalled from breast cancer screening.

METHODS

This prospective, multicenter, randomized controlled trial will be conducted at four centers and will include 528 patients recalled for suspicious breast lesions from the Dutch breast cancer screening program. Participants are randomized in two groups: (1) standard care using conventional breast imaging techniques as initial imaging after recall versus (2) work-up primarily based on CESM. Written informed consent will be collected prior to study inclusion. The primary outcome is the diagnostic accuracy for detection of breast cancer. Secondary outcomes are numbers of additional diagnostic exams, days until final diagnosis, health care costs, and experienced patient anxiety.

DISCUSSION

Based on previously published retrospective studies, we expect to demonstrate in this prospective multicenter randomized controlled trial, that using CESM as a primary work-up tool in women recalled from breast cancer screening is a more accurate, cost-effective, and patient-friendly strategy.

TRIAL REGISTRATION

Netherlands Trial Register, NL6413/NTR6589. Registered on 6 July, 2017.

Evaluation of single-view contrast-enhanced mammography as novel reading strategy: a non-inferiority feasibility study

BACKGROUND

Guidelines recommend screening of high-risk women using breast magnetic resonance imaging (MRI). Contrast-enhanced mammography (CEM) has matured, providing excellent diagnostic accuracy. To lower total radiation dose, evaluation of single-view (1 V) CEM exams might be considered instead of double-view (2 V) readings as an alternative reading strategy in women who cannot undergo MRI.

METHODS

This retrospective non-inferiority feasibility study evaluates whether the use of 1 V results in an acceptable sensitivity for detecting breast cancer (non-inferiority margin, - 10%). CEM images from May 2013 to December 2017 were included. 1 V readings were performed by consensus opinion of three radiologists, followed by 2 V readings being performed after 6 weeks. Cases were considered "malignant" if the final BI-RADS score was ≥ 4, enabling calculation of sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). Histopathological results or follow-up served as a gold standard.

RESULTS

A total of 368 cases were evaluated. Mean follow-up for benign or negative cases was 20.9 months. Sensitivity decreased by 9.6% from 92.9 to 83.3% when only 1 V was used for evaluation (p < 0.001). The lower limit of the 90% confidence interval around the difference in sensitivity between 1 V and 2 V readings was - 15% and lies below the predefined non-inferiority margin of - 10%. Hence, non-inferiority of 1 V to 2 V reading cannot be concluded. AUC for 1 V was significantly lower, 0.861 versus 0.899 for 2 V (p = 0.0174).

CONCLUSION

Non-inferiority of 1 V evaluations as an alternative reading strategy to standard 2 V evaluations could not be concluded. 1 V evaluations had lower diagnostic performance compared with 2 V evaluations.

KEY POINTS

• To lower radiation exposure used in contrast-enhanced mammography, we studied a hypothetical alternative strategy: single-view readings (1 V) versus (standard) double-view readings (2 V). • Based on our predefined margin of - 10%, non-inferiority of 1 V could not be concluded. • 1 V evaluation is not recommended as an alternative reading strategy to lower CEM-related radiation exposure.

Contrast-enhanced spectral mammography in the evaluation of breast suspicious calcifications: diagnostic accuracy and impact on surgical management

Background

Detecting pathological breast calcifications remains challenging. Based on recent studies, contrast-enhanced spectral mammography (CESM) was shown to be superior compared to full-field digital mammography (FFDM).

Purpose

To evaluate the diagnostic accuracy of CESM in suspicious breast calcifications and its impact on surgical decision-making.

Material and Methods

All screening recalled patients with suspicious calcifications that underwent CESM in the period October 2012 until September 2015 were included. One experienced radiologist provided a BI-RADS classification for the FFDM images only. The evaluation was repeated for the CESM exam. In a simulated tumor board meeting, two breast surgeons decided on the preferred surgical treatment (breast conservation therapy [BCT] versus mastectomy) for all malignant cases. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated defining BI-RADS ≥4 as being malignant. In addition, differences in surgical decision-making were analyzed and compared using McNemar’s test.

Results

In total, 147 women were included in this study (mean age = 61 years; age range = 49–75 years). Pathology showed 82 benign and 65 malignant lesions, of which 33 were ductal carcinomas in situ and 32 were invasive lesions. Diagnostic performances of CESM (differences compared to FFDM in brackets) were: sensitivity 93.8% (+3%), specificity 36.6% (−2.5%), PPV 54% (0%), and NPV 88.2% (+4%). Based on low-energy images, surgeons suggested BCT in 89% of the cases. Based on the CESM exam, no statistical changes in decisions were observed (86% BCT, P = 0.453).

Conclusion

CESM only slightly improves the diagnostic accuracy of the evaluation of breast calcifications. It is not of added value compared to FFDM in guiding surgical decision-making.

Microvasculature and intraplaque hemorrhage in atherosclerotic carotid lesions: a cardiovascular magnetic resonance imaging study

BACKGROUND

The presence of intraplaque haemorrhage (IPH) has been related to plaque rupture, is associated with plaque progression, and predicts cerebrovascular events. However, the mechanisms leading to IPH are not fully understood. The dominant view is that IPH is caused by leakage of erythrocytes from immature microvessels. The aim of the present study was to investigate whether there is an association between atherosclerotic plaque microvasculature and presence of IPH in a relatively large prospective cohort study of patients with symptomatic carotid plaque.

METHODS

One hundred and thirty-two symptomatic patients with ≥2 mm carotid plaque underwent cardiovascular magnetic resonance (CMR) of the symptomatic carotid plaque for detection of IPH and dynamic contrast-enhanced (DCE)-CMR for assessment of plaque microvasculature. Ktrans, an indicator of microvascular flow, density and leakiness, was estimated using pharmacokinetic modelling in the vessel wall and adventitia. Statistical analysis was performed using an independent samples T-test and binary logistic regression, correcting for clinical risk factors.

RESULTS

A decreased vessel wall Ktrans was found for IPH positive patients (0.051 ± 0.011 min- 1 versus 0.058 ± 0.017 min- 1, p = 0.001). No significant difference in adventitial Ktrans was found in patients with and without IPH (0.057 ± 0.012 min- 1 and 0.057 ± 0.018 min- 1, respectively). Histological analysis in a subgroup of patients that underwent carotid endarterectomy demonstrated no significant difference in relative microvessel density between plaques without IPH (n = 8) and plaques with IPH (n = 15) (0.000333 ± 0.0000707 vs. and 0.000289 ± 0.0000439, p = 0.585).

CONCLUSIONS

A reduced vessel wall Ktrans is found in the presence of IPH. Thus, we did not find a positive association between plaque microvasculature and IPH several weeks after a cerebrovascular event. Not only leaky plaque microvessels, but additional factors may contribute to IPH development.

TRIAL REGISTRATION

NCT01208025 . Registration date September 23, 2010. Retrospectively registered (first inclusion September 21, 2010). NCT01709045 , date of registration October 17, 2012. Retrospectively registered (first inclusion August 23, 2011).

Can high school students help to improve breast radiologists in detecting missed breast cancer lesions on full-field digital mammography?

Aim: To investigate whether full-field digital mammography (FFDM) and contrast-enhanced mammography (CEM), evaluated by non-experienced high school students, improves detection of missed breast cancer lesions on FFDM, in the same cohort of patients. Methods: Non-experienced first- and second year high school students examined fourteen cases of patients diagnosed with breast cancer. These cases consisted of missed breast cancer lesions on FFDM by a breast radiologist. Sensitivity of assessment of the students on FFDM and CEM was analysed and compared with the initial results of the breast radiologists. Results: A total of 134 high school students participated in this study. Mean age was 12.8 years (range 10-14). Based on FFDM, mean overall sensitivity of the students was 29.2% (18.9 - 39.6%). When recombined CEM images were used, mean overall sensitivity of students improved to 82.6% (74.0 - 91.2%) (p=0.001). Mean overall sensitivity of FFDM exams evaluated by radiologists was 75.7% (64.2 - 87.3%), which was lower when compared to student's evaluations on recombined CEM exams, yet not statistically significant (p=0.098). Conclusions: Contrast-enhanced mammography evaluated by non-experienced high school students might improve detection rate of breast cancer when compared to evaluations of only full-field digital mammography by radiologists.

Evaluation of pressure-controlled mammography compression paddles with respect to force-controlled compression paddles in clinical practice

Objectives

To reduce pain and discomfort associated with breast compression in mammography, a pressure-controlled compression paddle was recently introduced.

The objective was to evaluate the pressure-controlled paddle by comparing it to the standard force-controlled paddle.

Methods

Differences of compressed breast thickness (CBT), compression force, compression pressure, and average glandular dose (AGD) between annual follow-up full-field digital mammography exams of 3188 patients were retrospectively examined. Two groups were compared: (1) force-force group (FF-group), both examinations were performed with the force-controlled paddle, and (2) force-pressure group (FP-group), only the follow-up examination was performed with the pressure-controlled paddle.

In an additional group of patients, pain scores on a scale of 0 (no pain at all) to 10 (worst pain imaginable) were evaluated prospectively (n = 343) who were randomly assigned to either paddle.

Results

Median differences between follow-up exams in CBT, compression force, compression pressure, and AGD were for the FF- and FP-group respectively − 1.0 vs 0.0 mm (p < 0.001); 0.0 vs − 1.0 daN (p = 0.002); − 1.0 vs − 0.5 kPa (p = 0.005); and 0.05 vs − 0.02 mGy (p < 0.001). These differences were, although statistically significant, clinically non-relevant (defined as ΔCBT > ± 2 mm; Δforce > ± 2 daN; Δpressure > ± 1 kPa and ΔAGD > ± 0.1 mGy). The subanalysis dividing CBT into five categories revealed similar results. The median [interquartile range] pain scores were 6 [3, 7] and 5 [3, 7] for the force-controlled and pressure-controlled paddle, respectively, which was not significantly different (p = 0.113).

Conclusions

We observed no clinically relevant differences in CBT, compression force, compression pressure, AGD, or pain score between the force- and pressure-controlled paddle. As such, we found no basis for preferring one paddle over the other.

Key Points

• The pressure-controlled paddle did not show any clinically relevant changes in breast compression parameters compared to the force-controlled paddle.

• The pressure-controlled paddle did not lead to significant reduction in pain scores indicated by the patients compared to the force-controlled paddle.

• A large variation in compression force and compression pressure was observed in mammography exams for the both the force- and pressure-controlled compression paddle.

Electronic supplementary material

The online version of this article (10.1007/s00330-018-5953-6) contains supplementary material, which is available to authorized users.

Combined image interpretation of computed tomography and hybrid PET in head and neck cancer

Aim: Evaluation of potential synergistic effects of combined image interpretation of FDG PET using a gamma camera modified for coincidence detection (hybrid PET) and computed tomography (CT) and comparison of the diagnostic accuracy of hybrid PET and dedicated PET in patients with head and neck cancer. Methods: Forty-two patients with suspected primary or recurrent cancer were included. Twenty-four patients underwent dedicated PET in addition to attenuationcorrected hybrid PET using a one-day protocol. Results: Sensitivity, specificity and accuracy for detection of primary or recurrent head and neck cancer were 74, 73, and 74% for hybrid PET, 52, 82, and 60% for CT and 77, 82, and 79% for combined reading. With the combination of CT and hybrid PET all cases of recurrent disease were detected. The largest tumour not detected was 1.7 cm in diameter. Sensitivity, specificity and accuracy for the detection of neck sides with lymph node metastases were 69, 88, and 85% for hybrid PET, 62, 88, and 84% for CT, 69, 99, and 94% for combined image interpretation. With combined interpretation four involved neck sides were missed including two cases of microscopic metastases. Hybrid PET revealed concordant results to dedicated PET in all patients with respect to the detection of primary or recurrent tumour and in 45 of 48 neck sides (94%) with the same number of false negative findings. Conclusion: The combination of functional information of hybrid PET and morphological information of CT by the simple approach of combined image interpretation improves the sensitivity for the detection of primary/recurrent head and neck cancer and increases the specificity of lymph node staging compared to CT alone. The accuracy of hybrid PET and dedicated PET was almost identical.

[Prophylactic hydration to protect renal function from intravascular iodinated contrast material in patients at high risk of contrast-induced nephropathy (AMACING): a prospective, randomised, phase 3, controlled, open-label, non-inferiority trial]

BACKGROUND

Intravenous saline is recommended in clinical practice guidelines as the cornerstone for preventing contrast-induced nephropathy in patients with compromised renal function. However, clinical-effectiveness and cost-effectiveness of this prophylactic hydration treatment in protecting renal function has not been adequately studied in the population targeted by the guidelines, against a group receiving no prophylaxis. This was the aim of the AMACING trial.

METHODS

AMACING is a prospective, randomised, phase 3, parallel-group, open-label, non-inferiority trial of patients at risk of contrast-induced nephropathy according to current guidelines. High-risk patients (with an estimated glomerular filtration rate [eGFR] of 30-59 mL per min/1·73 m²) aged 18 years and older, undergoing an elective procedure requiring iodinated contrast material administration at Maastricht University Medical Centre, the Netherlands, were randomly assigned (1:1) to receive intravenous 0·9% NaCl or no prophylaxis. We excluded patients with eGFR lower than 30 mL per min/1·73 m², previous dialysis, or no referral for intravenous hydration. Randomisation was stratified by predefined risk factors. The primary outcome was incidence of contrast-induced nephropathy, defined as an increase in serum creatinine from baseline of more than 25% or 44 μmol/L within 2-6 days of contrast exposure, and cost-effectiveness of no prophylaxis compared with intravenous hydration in the prevention of contrast-induced nephropathy. We measured serum creatinine immediately before, 2-6 days, and 26-35 days after contrast-material exposure. Laboratory personnel were masked to treatment allocation. Adverse events and use of resources were systematically recorded. The non-inferiority margin was set at 2·1%. Both intention-to-treat and per-protocol analyses were done. This trial is registered with ClinicalTrials.gov, number NCT02106234.

FINDINGS

Between June 17, 2014, and July 17, 2016, 660 consecutive patients were randomly assigned to receive no prophylaxis (n=332) or intravenous hydration (n=328). 2-6 day serum creatinine was available for 307 (92%) of 332 patients in the no prophylaxis group and 296 (90%) of 328 patients in the intravenous hydration group. Contrast-induced nephropathy was recorded in eight (2·6%) of 307 non-hydrated patients and in eight (2·7%) of 296 hydrated patients. The absolute difference (no hydration vs hydration) was -0·10% (one-sided 95% CI -2·25 to 2·06; one-tailed p=0·4710). No hydration was cost-saving relative to hydration. No haemodialysis or related deaths occurred within 35 days. 18 (5·5%) of 328 patients had complications associated with intravenous hydration.

INTERPRETATION

We found no prophylaxis to be non-inferior and cost-saving in preventing contrast-induced nephropathy compared with intravenous hydration according to current clinical practice guidelines.

Quantitative performance evaluation of 124I PET/MRI lesion dosimetry in differentiated thyroid cancer

The aim was to investigate the quantitative performance of ¹²⁴I PET/MRI for pre-therapy lesion dosimetry in differentiated thyroid cancer (DTC). Phantom measurements were performed on a PET/MRI system (Biograph mMR, Siemens Healthcare) using ¹²⁴I and ¹⁸F. The PET calibration factor and the influence of radiofrequency coil attenuation were determined using a cylindrical phantom homogeneously filled with radioactivity. The calibration factor was 1.00  ±  0.02 for ¹⁸F and 0.88  ±  0.02 for ¹²⁴I. Near the radiofrequency surface coil an underestimation of less than 5% in radioactivity concentration was observed. Soft-tissue sphere recovery coefficients were determined using the NEMA IEC body phantom. Recovery coefficients were systematically higher for ¹⁸F than for ¹²⁴I. In addition, the six spheres of the phantom were segmented using a PET-based iterative segmentation algorithm. For all ¹²⁴I measurements, the deviations in segmented lesion volume and mean radioactivity concentration relative to the actual values were smaller than 15% and 25%, respectively. The effect of MR-based attenuation correction (three- and four-segment µ-maps) on bone lesion quantification was assessed using radioactive spheres filled with a K₂HPO₄ solution mimicking bone lesions. The four-segment µ-map resulted in an underestimation of the imaged radioactivity concentration of up to 15%, whereas the three-segment µ-map resulted in an overestimation of up to 10%. For twenty lesions identified in six patients, a comparison of ¹²⁴I PET/MRI to PET/CT was performed with respect to segmented lesion volume and radioactivity concentration. The interclass correlation coefficients showed excellent agreement in segmented lesion volume and radioactivity concentration (0.999 and 0.95, respectively). In conclusion, it is feasible that accurate quantitative ¹²⁴I PET/MRI could be used to perform radioiodine pre-therapy lesion dosimetry in DTC.

Added value of dedicated axillary hybrid 18F-FDG PET/MRI for improved axillary nodal staging in clinically node-positive breast cancer patients: a feasibility study

Purpose

To investigate the feasibility and potential added value of dedicated axillary 18F-FDG hybrid PET/MRI, compared to standard imaging modalities (i.e. ultrasound [US], MRI and PET/CT), for axillary nodal staging in clinically node-positive breast cancer.

Methods

Twelve patients with clinically node-positive breast cancer underwent axillary US and dedicated axillary hybrid 18F-FDG PET/MRI. Nine of the 12 patients also underwent whole-body PET/CT. Maximum standardized uptake values (SUVmax) were measured for the primary breast tumor and the most FDG-avid axillary lymph node. A positive axillary lymph node on dedicated axillary hybrid PET/MRI was defined as a moderate to very intense FDG-avid lymph node. The diagnostic performance of dedicated axillary hybrid PET/MRI was calculated by comparing quantitative and its qualitative measurements to results of axillary US, MRI and PET/CT. The number of suspicious axillary lymph nodes was subdivided as follows: N0 (0 nodes), N1 (1–3 nodes), N2 (4–9 nodes) and N3 (≥ 10 nodes).

Results

According to dedicated axillary hybrid PET/MRI findings, seven patients were diagnosed with N1, four with N2 and one with N3. With regard to mean SUVmax, there was no significant difference in the primary tumor (9.0 [±5.0] vs. 8.6 [±5.7], p = 0.678) or the most FDG-avid axillary lymph node (7.8 [±5.3] vs. 7.7 [±4.3], p = 0.767) between dedicated axillary PET/MRI and PET/CT. Compared to standard imaging modalities, dedicated axillary hybrid PET/MRI resulted in changes in nodal status as follows: 40% compared to US, 75% compared to T2-weighted MRI, 40% compared to contrast-enhanced MRI, and 22% compared to PET/CT.

Conclusions

Adding dedicated axillary 18F-FDG hybrid PET/MRI to diagnostic work-up may improve the diagnostic performance of axillary nodal staging in clinically node-positive breast cancer patients.

Presence and extent of cardiac computed tomography angiography defined coronary artery disease in patients presenting with syncope

Background

In syncope patients, presence of coronary artery disease (CAD) is associated with poor prognosis. However, data concerning CAD prevalence in syncope patients without known cardiovascular disease are lacking. Therefore, the aim of this study was to investigate presence and extent of CAD in syncope patients.

Methods

We included 142 consecutive patients presenting with syncope at the outpatient cardiology clinic who underwent coronary computed tomography (CT) angiography. Syncope type was ascertained by two reviewers, blinded for coronary CT angiography results. Of the patients, 49 had cardiac syncope (arrhythmia or structural cardiopulmonary disease) and 93 had non-cardiac syncope (reflex [neurally-mediated], orthostatic or of unknown cause). Cardiac syncope patients were compared with matched stable chest pain patients regarding age, gender, smoking status, diabetes mellitus type 2 and systolic blood pressure.

Results

Distribution of CAD presence and extent in cardiac and non-cardiac syncope patients was as follows: 72% versus 48% any CAD; 31% versus 26% mild, 8% versus 14% moderate and 33% versus 7% severe CAD.

Compared with non-cardiac syncope, patients with cardiac syncope had a significantly higher CAD presence and extent (p = 0.001). Coronary calcium score, segment involvement and stenosis score were also higher in cardiac syncope patients (p-values ≤0.004). Compared to the chest pain control group, patients with cardiac syncope showed a higher, however, non-significant, prevalence of any CAD (72% versus 63%) and severe CAD (33% versus 19%).

Conclusion

Patients with cardiac syncope show a high presence and extent of CAD in contrast to non-cardiac syncope patients. These results suggest that CAD may play an important role in the occurrence of cardiac syncope.

Electronic supplementary material

The online version of this article (doi: 10.1007/s12471-017-0970-7) contains supplementary material, which is available to authorized users.

Quantitative and qualitative assessment of left ventricular volume with ECG-gated multislice spiral CT: value of different image reconstruction algorithms in comparison to MRI

Purpose: To assess the value of different image reconstruction algorithms for assessment of the left ventricular function using retrospectively ECG-gated multislice spiral computed tomography (MSCT) of the heart.

Material and Methods: MSCT and cine magnetic resonance (MR) imaging of the heart were performed in 15 patients. For MSCT, standard and multisegmental image reconstruction with improved temporal resolution were used. Standardized multiplanar reformats in the short axis and long axis views were reconstructed from MSCT data. End-systolic (ESV) and end-diastolic volume (EDV), stroke volume (SV), ejection fraction (EF) and myocardial mass (MM) were calculated. Left ventricular wall motion was assessed qualitatively.

Results: MSCT was in acceptable agreement with MR imaging for quantification of the ventricular function. According to the Bland–Altman approach the mean differences for the left ventricular volumes (ESV, EDV, SV) ranged from −9.6 ml to 3.1 ml with standard image reconstruction and from −0.6 ml to 1.9 ml utilizing multisegmental image reconstruction with limits of agreement ranging from −26.6 ml to 12.5 ml and −15.6 ml to 15.0 ml, respectively. Applying the multisegmental image reconstruction algorithm, a significantly improved agreement with the MR data was found for EDV, SV and EF. For wall motion analysis, standard image reconstruction showed a significant difference to MR imaging with a correspondence in 83.75% of the 240 assessed segments, while multisegmental image reconstruction agreed with MR imaging in 92.5% of the segments.

Conclusion: Multisegmental image reconstruction improves the quantitative assessment of left ventricular function when compared to standard image reconstruction. Multisegmental image reconstruction allows qualitative wall motion analysis.

Value of 3D-volume rendering in the assessment of coronary arteries with retrospectively ECG-gated multislice spiral CT

Purpose: To assess the diagnostic value and measurement precision of 3D volume rendering technique (3D-VRT) from retrospectively ECG-gated multislice spiral CT (MSCT) data sets for imaging of the coronary arteries.

Material and Methods: In 35 patients, retrospectively ECG-gated MSCT of the heart using a four detector row MSCT scanner with a standardized examination protocol was performed as well as quantitative X-ray coronary angiography (QCA). The MSCT data was assessed on segmental basis using 3D-VRT exclusively. The coronary artery diameters were measured at the origin of each main coronary branch and 1 cm, 3 cm and 5 cm distally. The minimum, maximum and mean diameters were determined from MSCT angiography and compared to QCA.

Results: A total of 353 of 525 (67.2%) coronary artery segments were assessable by MSCT angiography. The proximal segments were more often assessable when compared to the distal segments. Stenoses were detected with a sensitivity of 82.6% and a specificity of 92.8%. According to the Bland-Altmanmethod the mean differences between QCA and MSCT ranged from −0.55 to 1.07 mm with limits of agreement from −2.2 mm to −2.7 mm.

Conclusion: When compared to QCA, the ability of 3D-VRT to quantitatively assess coronary artery diameters and coronary artery stenoses is insufficient for clinical purposes.

Phase-based vascular input function: Improved quantitative DCE-MRI of atherosclerotic plaques

PURPOSE

Quantitative pharmacokinetic modeling of dynamic contrast-enhanced (DCE)-MRI can be used to assess atherosclerotic plaque microvasculature, which is an important marker of plaque vulnerability. Purpose of the present study was (1) to compare magnitude- versus phase-based vascular input functions (m-VIF vs ph-VIF) used in pharmacokinetic modeling and (2) to perform model calculations and flow phantom experiments to gain more insight into the differences between m-VIF and ph-VIF.

METHODS

Population averaged m-VIF and ph-VIFs were acquired from 11 patients with carotid plaques and used for pharmacokinetic analysis in another 17 patients. Simulations, using the Bloch equations and the MRI scan geometry, and flow phantom experiments were performed to determine the effect of local blood velocity on the magnitude and phase signal enhancement.

RESULTS

Simulations and flow phantom experiments revealed that flow within the lumen can lead to severe underestimation of m-VIF, while this is not the case for the ph-VIF. In line, the peak concentration of the m-VIF is significantly lower than ph-VIF (p < 0.001), in vivo. Quantitative model parameters for m- and ph-VIF differed in absolute values but were moderate to strongly correlated with each other [K(trans) Spearman's ρ > 0.93 (p < 0.001) and vp Spearman's ρ > 0.58 (p < 0.05)].

CONCLUSIONS

m-VIF is strongly influenced by local blood velocity, which leads to underestimation of the contrast medium concentration. Therefore, it is advised to use ph-VIF for DCE-MRI analysis of carotid plaques for accurate quantification.

Altered Hippocampal White Matter Connectivity in Type 2 Diabetes Mellitus and Memory Decrements

Type 2 diabetes mellitus is associated with cognitive decrements. Specifically affected cognitive domains are learning and memory, for which the hippocampus plays an essential role. The pathophysiological mechanism remains to be revealed. The present study examined whether local hippocampal microstructure and white matter connectivity are related to type 2 diabetes and memory performance. Forty participants with type 2 diabetes and 38 participants without type 2 diabetes underwent detailed cognitive assessment and 3-Tesla diffusion magnetic resonance imaging (MRI). Diffusion MRI was performed to assess microstructure (fractional anisotropy and mean diffusivity) and white matter connectivity (tract volume) of the hippocampus, which were compared between participants with and without type 2 diabetes. No differences in hippocampal microstructure were observed. Participants with type 2 diabetes had fewer white matter connections between the hippocampus and frontal lobe (P = 0.017). Participants who scored lower on memory function, regardless of type 2 diabetes, had fewer white matter connections between the hippocampus and temporal lobe (P = 0.017). Taken together, type 2 diabetes and memory decrements appear to be associated with altered hippocampal white matter connectivity.

The role of dual energy CT in differentiating between brain haemorrhage and contrast medium after mechanical revascularisation in acute ischaemic stroke

OBJECTIVES

To assess the feasibility of dual energy computed tomography (DE-CT) in intra-arterially treated acute ischaemic stroke patients to discriminate between contrast extravasation and intracerebral haemorrhage.

METHODS

Thirty consecutive acute ischaemic stroke patients following intra-arterial treatment were examined with DE-CT. Simultaneous imaging at 80 kV and 140 kV was employed with calculation of mixed images. Virtual unenhanced non-contrast (VNC) images and iodine overlay maps (IOM) were calculated using a dedicated brain haemorrhage algorithm. Mixed images alone, as "conventional CT", and DE-CT interpretations were evaluated and compared with follow-up CT.

RESULTS

Eight patients were excluded owing to a lack of follow-up or loss of data. Mixed images showed intracerebral hyperdense areas in 19/22 patients. Both haemorrhage and residual contrast material were present in 1/22. IOM suggested contrast extravasation in 18/22 patients; in 16/18 patients this was confirmed at follow-up. The positive predictive value (PPV) of mixed imaging alone was 25 %, with a negative predictive value (NPV) of 91 % and accuracy of 63 %. The PPV for detection of haemorrhage with DE-CT was 100 %, with an NPV of 89 % and accuracy improved to 89 %.

CONCLUSIONS

Dual energy computed tomography improves accuracy and diagnostic confidence in early differentiation between intracranial haemorrhage and contrast medium extravasation in acute stroke patients following intra-arterial revascularisation.

KEY POINTS

• Contrast material and haemorrhage have similar density on conventional 120-kV CT. • Contrast material hinders interpretation of CT in stroke patients after recanalisation. • Iodine and haemorrhage have different attenuation at lower kVs. • Dual energy CT improves accuracy in early differentiation of haemorrhage and contrast extravasation. • Early differentiation between iodine and haemorrhage helps to initiate therapy promptly.

Characterization of tumor heterogeneity using dynamic contrast enhanced CT and FDG-PET in non-small cell lung cancer

PURPOSE

Dynamic contrast-enhanced CT (DCE-CT) quantifies vasculature properties of tumors, whereas static FDG-PET/CT defines metabolic activity. Both imaging modalities are capable of showing intra-tumor heterogeneity. We investigated differences in vasculature properties within primary non-small cell lung cancer (NSCLC) tumors measured by DCE-CT and metabolic activity from FDG-PET/CT.

METHODS

Thirty three NSCLC patients were analyzed prior to treatment. FDG-PET/CT and DCE-CT were co-registered. The tumor was delineated and metabolic activity was segmented on the FDG-PET/CT in two regions: low (<50% maximum SUV) and high (≥50% maximum SUV) metabolic uptake. Blood flow, blood volume and permeability were calculated using a maximum slope, deconvolution algorithm and a Patlak model. Correlations were assessed between perfusion parameters for the regions of interest.

RESULTS

DCE-CT provided additional information on vasculature and tumor heterogeneity that was not correlated to metabolic tumor activity. There was no significant difference between low and high metabolic active regions for any of the DCE-CT parameters. Furthermore, only moderate correlations between maximum SUV and DCE-CT parameters were observed.

CONCLUSIONS

No direct correlation was observed between FDG-uptake and parameters extracted from DCE-CT. DCE-CT may provide complementary information to the characterization of primary NSCLC tumors over FDG-PET/CT imaging.

The role of magnetic resonance imaging in assessing residual disease and pathologic complete response in breast cancer patients receiving neoadjuvant chemotherapy: a systematic review

OBJECTIVES

This systematic review aimed to assess the role of magnetic resonance imaging (MRI) in evaluating residual disease extent and the ability to detect pathologic complete response (pCR) after neoadjuvant chemotherapy for invasive breast cancer.

METHODS

PubMed, the Cochrane Library, MEDLINE, and Embase databases were searched for relevant studies published until 1 July 2012. After primary selection, two reviewers independently assessed the content of each eligible study using a standardised extraction form and pre-defined inclusion and exclusion criteria.

RESULTS

A total of 35 eligible studies were selected. Correlation coefficients of residual tumour size assessed by MRI and pathology were good, with a median value of 0.698. Reported sensitivity, specificity, positive predictive value and negative predictive value for predicting pCR with MRI ranged from 25 to 100 %, 50-97 %, 47-73 % and 71-100 %, respectively. Both overestimation and underestimation were observed. MRI proved more accurate in determining residual disease than physical examination, mammography and ultrasound. Diagnostic accuracy of MRI after neoadjuvant chemotherapy could be influenced by treatment regimen and breast cancer subtype.

CONCLUSIONS

Breast MRI accuracy for assessing residual disease after neoadjuvant chemotherapy is good and surpasses other diagnostic means. However, both overestimation and underestimation of residual disease extent could be observed.

MAIN MESSAGES

• Breast MRI accuracy for assessing residual disease is good and surpasses other diagnostic means. • Correlation coefficients of residual tumour size assessed by MRI and pathology were considered good. • However, both overestimation and underestimation of residual disease were observed. • Diagnostic accuracy of MRI seems to be affected by treatment regimen and breast cancer subtype.

Pre-treatment differences and early response monitoring of neoadjuvant chemotherapy in breast cancer patients using magnetic resonance imaging: a systematic review

OBJECTIVES

To assess whether magnetic resonance imaging (MRI) can identify pre-treatment differences or monitor early response in breast cancer patients receiving neoadjuvant chemotherapy.

METHODS

PubMed, Cochrane library, Medline and Embase databases were searched for publications until January 1, 2012. After primary selection, studies were selected based on predefined inclusion/exclusion criteria. Two reviewers assessed study contents using an extraction form.

RESULTS

In 15 studies, which were mainly underpowered and of heterogeneous study design, 31 different parameters were studied. Most frequently studied parameters were tumour diameter or volume, K(trans), K(ep), V(e), and apparent diffusion coefficient (ADC). Other parameters were analysed in only two or less studies. Tumour diameter, volume, and kinetic parameters did not show any pre-treatment differences between responders and non-responders. In two studies, pre-treatment differences in ADC were observed between study groups. At early response monitoring significant and non-significant changes for all parameters were observed for most of the imaging parameters.

CONCLUSIONS

Evidence on distinguishing responders and non-responders to neoadjuvant chemotherapy using pre-treatment MRI, as well as using MRI for early response monitoring, is weak and based on underpowered study results and heterogeneous study design. Thus, the value of breast MRI for response evaluation has not yet been established.

KEY POINTS

Few well-validated pre-treatment MR parameters exist that identify responders and non-responders. Eligible studies showed heterogeneous study designs which hampered pooling of data. Confounders and technical variations of MRI accuracy are not studied adequately. Value of MRI for response evaluation needs to be established further.

Potential of integrated [18F] fluorodeoxyglucose positron-emission tomography/CT in identifying vulnerable carotid plaques

BACKGROUND AND PURPOSE

There is a need for improved risk stratification of patients with TIA/stroke and carotid atherosclerosis. The purpose of this study was to prospectively investigate the potential of integrated (18)F-FDG PET/MDCT in identifying vulnerable carotid plaques.

MATERIALS AND METHODS

Fifty patients with TIA/stroke with an ipsilateral carotid plaque causing <70% stenosis and a plaque on the contralateral asymptomatic side underwent integrated (18)F-FDG PET/MDCT within 36.1 ± 20.0 days (range, 9-95 days) of the last symptoms. Carotid plaque (18)F-FDG uptake was measured as both the mean and maximum blood-normalized SUV, known as the TBR. Using MDCT, we assessed volumes of vessel wall and individual plaque components.

RESULTS

Mean TBR was only significantly larger in the ipsilateral plaques of patients who were imaged within 38 days (1.24 ± 0.04 [SE] versus 1.17 ± 0.05, P = .014). This also accounted for maximum TBR (1.53 ± 0.06 versus 1.42 ± 0.06, P = .015). MDCT-assessed vessel wall and LRNC volumes were larger in ipsilateral plaques of all patients (982.3 ± 121.3 versus 811.3 ± 106.6 mm(3), P = .016; 164.7 ± 26.1 versus 134.3 ± 35.2 mm(3), P = .026, respectively).

CONCLUSIONS

In the present study, (18)F-FDG PET only detected significant differences between ipsilateral and contralateral asymptomatic plaques in patients with TIA/stroke who were imaged within 38 days, whereas MDCT detected larger vessel wall and LRNC volumes, regardless of time after symptoms. In view of the substantial overlap in measurements of both sides, it remains to be determined whether the differences we found will be clinically meaningful.

Performance evaluation of a computer-aided detection algorithm for solid pulmonary nodules in low-dose and standard-dose MDCT chest examinations and its influence on radiologists

The aim of the study was to evaluate the performance of a computer-aided detection (CAD) algorithm in low-dose and full-dose multidetector-row CT (MDCT) of the thorax and its impact on radiologists' performance. Chest CT examinations of 77 patients were evaluated retrospectively for pulmonary nodules. All patients had undergone a 16-slice MDCT chest examination with a standard acquisition protocol. Artificial image noise was added to the raw data to simulate image acquisition at 10 mAs(eff.) The data were transferred to dedicated lung analysis software (LungCare) with a prototype CAD algorithm (LungCAD). CAD was applied to both dose settings. Images were read by a radiologist and a first-year resident with and without the software at both dose settings. All images were reviewed in consensus by the two radiologists to set the reference standard. Sensitivity results with respect to the reference standard were compared. No statistically significant differences in the detection rate for all pulmonary nodules could be found between low-dose and full-dose settings for the CAD software alone (p = 0.0065). Both radiologists displayed a statistically significant increase in sensitivity with the use of CAD (p<0.0001). In conclusion, CAD is beneficial in both low-dose and standard-dose settings. This may be beneficial in reducing false-negative diagnosis in lung cancer screening, standard chest examinations and the search for metastases.

Pediatric multidetector computed tomography using tube current modulation and a patient image gallery

BACKGROUND

Dose reduction is crucial in pediatric multidetector computed tomography (MDCT).

PURPOSE

To perform pediatric 16-slice MDCT using tube current modulations and to adjust prospectively the tube current using a patient image gallery (IG) providing simulated dose-reduced protocols; and to evaluate and compare the image quality of the IG and the clinical MDCT.

MATERIAL AND METHODS

30 examinations (thorax, n = 15; abdomen, n = 8; pelvis, n = 7) in 20 patients (nine male, age 8.05 +/- 7.33 years, weight 29.8 +/- 24.02 kg) were performed according to an IG on a 16-slice MDCT with additional use of online tube current modulation (CARE Dose). Three radiologists visually assessed image quality from the IG and actual 16-slice MDCT scans. For objective analysis, image noise was determined.

RESULTS

Statistical analysis showed moderate concordance in objective (K = 0.68-0.78) and subjective (K = 0.33-0.64) image assessment between the IG and clinical 16-slice MDCT scans. Depending on the weight group and clinical question, no or only minor dose reductions in the chest, but moderate to considerable reductions in the abdominal/pelvic 16-slice MDCT scans compared to previously used pediatric protocols were achieved. Extra dose reduction was achieved due to additional use of CARE Dose depending on age group and scan region (mean 8.6-23.9%).

CONCLUSION

The IG enabled us to prospectively reduce the tube current and adapt the required image quality to the clinical question. Additional dose reduction was achieved with application of CARE Dose; nevertheless, the images are comparable to the simulated images of the IG.

Computertomografisch gesteuerte Interventionen bei Kindern

In pediatric CT-guided interventions specific features have to be taken into account. Due to a lack of cooperation or limited ability to cooperate, procedures are often performed using analgosedation or general anesthesia. To provide radiation protection, justified indication for CT-guided intervention is necessary and sonography and MRI are to be preferred whenever possible. CT examinations also need to be dose-adapted with sequential scanning and a tube voltage and tube current reduction compared to pediatric diagnostic CT studies must be ensured. Gonad shields are recommended for male patients. Biopsy device selection depends on the assumed tumor entity since histology and also immunohistochemical, molecular pathological and cytogenetical analysis are necessary to differentiate pediatric tumors (small, round, blue cell tumors). In addition to diagnostic procedures, therapeutic interventions (drainage, injection therapies, neurolysis, and radiofrequency ablation) can also be used in children and can provide an alternative to surgery in selected cases. With justified indications and precise performance, CT-guided interventions can be successful in pediatric patients with limited risks.