Deepa Gopalan

Detection of Atherosclerotic Inflammation by 68Ga-DOTATATE PET Compared to [18F]FDG PET Imaging

Background Inflammation drives atherosclerotic plaque rupture. Although inflammation can be measured using fluorine-18-labeled fluorodeoxyglucose positron emission tomography ([18F]FDG PET), [18F]FDG lacks cell specificity, and coronary imaging is unreliable because of myocardial spillover. Objectives This study tested the efficacy of gallium-68-labeled DOTATATE (68Ga-DOTATATE), a somatostatin receptor subtype-2 (SST2)-binding PET tracer, for imaging atherosclerotic inflammation. Methods We confirmed 68Ga-DOTATATE binding in macrophages and excised carotid plaques. 68Ga-DOTATATE PET imaging was compared to [18F]FDG PET imaging in 42 patients with atherosclerosis. Results Target SSTR2 gene expression occurred exclusively in “proinflammatory” M1 macrophages, specific 68Ga-DOTATATE ligand binding to SST2 receptors occurred in CD68-positive macrophage-rich carotid plaque regions, and carotid SSTR2 mRNA was highly correlated with in vivo 68Ga-DOTATATE PET signals (r = 0.89; 95% confidence interval [CI]: 0.28 to 0.99; p = 0.02). 68Ga-DOTATATE mean of maximum tissue-to-blood ratios (mTBRmax) correctly identified culprit versus nonculprit arteries in patients with acute coronary syndrome (median difference: 0.69; interquartile range [IQR]: 0.22 to 1.15; p = 0.008) and transient ischemic attack/stroke (median difference: 0.13; IQR: 0.07 to 0.32; p = 0.003). 68Ga-DOTATATE mTBRmax predicted high-risk coronary computed tomography features (receiver operating characteristics area under the curve [ROC AUC]: 0.86; 95% CI: 0.80 to 0.92; p < 0.0001), and correlated with Framingham risk score (r = 0.53; 95% CI: 0.32 to 0.69; p <0.0001) and [18F]FDG uptake (r = 0.73; 95% CI: 0.64 to 0.81; p < 0.0001). [18F]FDG mTBRmax differentiated culprit from nonculprit carotid lesions (median difference: 0.12; IQR: 0.0 to 0.23; p = 0.008) and high-risk from lower-risk coronary arteries (ROC AUC: 0.76; 95% CI: 0.62 to 0.91; p = 0.002); however, myocardial [18F]FDG spillover rendered coronary [18F]FDG scans uninterpretable in 27 patients (64%). Coronary 68Ga-DOTATATE PET scans were readable in all patients. Conclusions We validated 68Ga-DOTATATE PET as a novel marker of atherosclerotic inflammation and confirmed that 68Ga-DOTATATE offers superior coronary imaging, excellent macrophage specificity, and better power to discriminate high-risk versus low-risk coronary lesions than [18F]FDG. (Vascular Inflammation Imaging Using Somatostatin Receptor Positron Emission Tomography [VISION]; NCT02021188)

Diagnosis of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is the only potentially curable form of pulmonary hypertension. Rapid and accurate diagnosis is pivotal for successful treatment. Clinical signs and symptoms can be nonspecific and risk factors such as history of venous thromboembolism may not always be present. Echocardiography is the recommended first diagnostic step. Cardiopulmonary exercise testing is a complementary tool that can help to identify patients with milder abnormalities and chronic thromboembolic disease, triggering the need for further investigation. Ventilation/perfusion (V′/Q′) scintigraphy is the imaging methodology of choice to exclude CTEPH. Single photon emission computed tomography V′/Q′ is gaining popularity over planar imaging. Assessment of pulmonary haemodynamics by right heart catheterisation is mandatory, although there is increasing interest in noninvasive haemodynamic evaluation. Despite the status of digital subtraction angiography as the gold standard, techniques such as computed tomography (CT) and magnetic resonance imaging are increasingly used for characterising the pulmonary vasculature and assessment of operability. Promising new tools include dual-energy CT, combination of rotational angiography and cone beam CT, and positron emission tomography. These innovative procedures not only minimise misdiagnosis, but also provide additional vascular information relevant to treatment planning. Further research is needed to determine how these modalities will fit into the diagnostic algorithm for CTEPH. CTEPH is a curable form of pulmonary hypertension which requires multimodality imaging for accurate diagnosis http://ow.ly/oTVT308CcD4

A cohort study reveals myocarditis to be a rare and life-threatening presentation of large vessel vasculitis

BACKGROUNDnThe predominant forms of adult large vessel vasculitis (LVV) are giant cell arteritis (GCA) and Takayasu arteritis (TA). Cardiac involvement in LVV is a cause of morbidity and mortality, particularly in TA. Cardiac failure is most commonly secondary to uncontrolled arterial hypertension or myocardial ischaemia. Pulmonary hypertension and aortic valve incompetence following ascending aortic dilatation represent other serious cardiovascular complications. However, cardiac failure as a consequence of myocarditis is rarely reported, principally in single case reports or in autopsy studies.nnnMETHODSnThe Imperial College LVV database was, retrospectively, reviewed to identify patients with cardiac involvement at presentation. Patients with evidence for myocarditis were identified. The cardiac presentation, imaging studies and subsequent medical and surgical management were reviewed in detail.nnnRESULTSnThe cohort included 139 patients with TA and 24 with GCA. Sixteen presented with cardiac failure without a history of ischaemic coronary heart disease, 14 (10%) with TA and 2 (8.3%) with GCA. Cardiovascular disease identified at presentation included aortic regurgitation (n = 11), myocarditis (n = 4) and hypertensive cardiomyopathy secondary to renal artery stenosis (n = 1). Those patients with evidence of myocarditis at presentation (2.8%) underwent transthoracic echocardiography and cardiac magnetic resonance imaging (CMR). These non-invasive techniques were sufficient for diagnosis of clinically significant myocarditis. Furthermore, they were subsequently used to monitor response to treatment, with serial improvement in left ventricular ejection fraction (LVEF) observed in all 4 patients (p < 0.05). Prednisolone plus cyclophosphamide (CyC) therapy was associated with significant improvement in heart failure symptoms and LVEF in 3 cases. In one case where CyC was contraindicated, tocilizumab treatment led to marked improvement in cardiac symptoms.nnnCONCLUSIONnClinically significant myocarditis in LVV remains a rare but serious presentation. Non-invasive imaging techniques offer an alternative to the gold-standard myocardial biopsy. Initial aggressive immunosuppressive therapy is recommended and led to significant improvements in LVEF and cardiac status.

Complications of myocardial infarction on multidetector- row computed tomography of chest

Myocardial infarction (MI) secondary to coronary artery disease remains the leading cause of death in the western world. The advent of early reperfusion therapy has substantially decreased in-hospital mortality and has improved the outcome in survivors of the acute phasexa0of MI. Complications of MI include ischaemic, mechanical, arrhythmic, embolic and inflammatory disturbances. Although some of these complications may be infrequent, their importance is underscored because of the potential ability to correct them with early diagnosis and appropriate treatment. The majority of these complications will be detected on clinical examination and confirmed by echocardiography. Some patients may undergo non-electrocardiogram (ECG)-gated thoracic multidetector-row computed tomography (MDCT) due to non-specific presentation. In this group, it is imperative for the radiologist to be aware of and be confident in diagnosing the complications secondary to MI. This review illustrates the spectrum and imaging features of acute and chronic complications of MI that can be visualized on both ECG-gated cardiac and non-ECG-gated thoracic MDCT.

Acute and sub-acute sinus node dysfunction following pulmonary vein isolation: a case series

Abstract Six patients submitted to paroxysmal atrial fibrillation (AF) ablation presented with long post-reversion sinus pauses between a few hours to 2 months after their procedures, causing recurrent syncope or pre-syncope. Five patients required urgent pacemaker implantation. None of these patients had previous symptoms suggestive of sick sinus syndrome (SSS) or a history of symptomatic bradycardia. Acute or sub-acute sinus node dysfunction (SND) has only recently been suggested as a potential complication of AF ablation. In three of our patients, the sinus node artery (SNA) was exclusively left-sided, running along the high anterior left atrium in close proximity to the ostia of the left and right superior pulmonary veins. In a fourth case, the SNA originated from the right coronary artery and coursed along the high anterior left atrium close to the ostium of the right superior pulmonary vein. In the remaining two cases, a pre-procedural assessment of the SNA was not possible, although a post-procedural CT scan performed in one of these did not reveal any signs of the SNA. Overdrive suppression of the sinus node exacerbated by thermal injury to the SNA may have been implicated. This was supported by (i) the lack of symptoms/signs suggestive of SSS pre-ablation, (ii) post-ablation acute/sub-acute pronounced post-AF reversion sinus pauses, and (iii) the observation that the SNA coursed along areas typically ablated during an AF ablation. Although this case series is hypothesis-generating only, we hope it will raise the awareness for the occurrence of acute/sub-acute SND as a potential complication of AF ablation.

Update of Screening and Diagnostic Modalities for Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

OBJECTIVEnPulmonary arterial hypertension (PAH) has high morbidity and mortality in connective tissue diseases (CTDs), especially systemic sclerosis (SSc). In this systematic review, we provide an update on screening measures for early detection of PAH in CTD.nnnMETHODSnManuscripts published between July 2012 and October 2017, which incorporated screening measures to identify patients with PAH by right heart catheterization, were identified. Risk of bias was assessed using the QUADAS-2 tool.nnnRESULTSnThe systematic review resulted in 1514 unique citations and 22 manuscripts were included for final review; the majority of manuscripts had a lower risk of bias based on the QUADAS-2 tool. There were 16 SSc cohort studies and 6 case-control studies (SSc 4, SLE 2). Four SSc cohort studies evaluated transthoracic echocardiography (TTE) only. Eight SSc cohort studies evaluated composite measures including ASIG, DETECT, and a combination of tricuspid regurgitation velocity (TRV) and PFT variables. DETECT and ASIG had greater sensitivity and negative predictive value (NPV) compared to the 2009 ESC/ERS guidelines in different cohorts. The addition of PFT variables, such as DLCO or FVC/ DLCO ratio, to TRV, resulted in greater sensitivity and NPV compared to TRV alone.nnnCONCLUSIONnCurrent screening for PAH in CTDs is centered on SSc. Data continues to support the use of TTE and provides additional evidence for use of composite measures.

Pictorial review: non-anatomical cardiovascular gas: causes, appearances and consequences

Gas does not occur naturally in the cardiovascular system, although it is not unusual to identify it on imaging. The true incidence is difficult to know as asymptomatic cases are rarely recorded. In iatrogenic instance, this occurs when atmospheric air enters the cardiovascular system from a high to low pressure, or when gas is forcibly injected into a vessel. The source of air must be promptly identified and treatment must be expedited to reduce morbidity and mortality. This pictorial review aims to give an overview of the causes (with particular emphasis on the conditions that may be encountered by a Radiologist), appearances of cardiovascular gas, and any subsequent treatment.

Complications of pulmonary hypertension: a pictorial review

Pulmonary hypertension (PH) is a rare disease with a significant morbidity and mortality if untreated. The disease has a multifactorial aetiology and is often associated with insidious onset of signs and symptoms. Multimodality imaging is often required for establishing the diagnosis, evaluating the underlying haemodynamic compromise and follow-up after institution of therapy. The range of potential complications associated with PH vary widely. We aimed to summarize the imaging findings of complications that the radiologist should be familiar with.

Use of somatostatin receptor PET to differentiate between high-risk and low-risk atherosclerotic lesions: a prospective clinical study

Abstract Background Inflammation drives atherosclerotic plaque rupture that underlies most myocardial infarctions and strokes. Upregulation of somatostatin receptor subtype-2 (SST 2 ) occurs on the cell surface of activated macrophages, offering a potential imaging target for tracking vascular inflammation. We tested the hypothesis that SST 2 PET-CT imaging with 68 Ga-DOTATATE can detect high-risk carotid and coronary plaque inflammation. We then compared its efficacy with 18 F-fludeoxyglucose ( 18 F-FDG), which has limited use in coronary imaging. Methods Prospective sequential 68 Ga-DOTATATE PET and 18 F-FDG PET imaging, plus CT angiography, were performed in 42 patients with either a recent cardiovascular event (within 3 months of imaging) or stable atherosclerosis, and at least 30% carotid or coronary artery stenosis. Images were analysed, with investigators masked to clinical details, to derive median (IQR) maximum arterial tissue-to-background ratio (TBR). Arterial TBRs were statistically evaluated against clinical and biochemical data, as well as CT-derived plaque morphology. Findings 70 carotid arteries and 230 coronary segments were included. 24 patients (57%) had a recent cardiovascular event. 68 Ga-DOTATATE TBR (1·98 [1·67–2·14]) was higher in symptomatic carotid arteries than in contralateral arteries (1·77 [1·46–2·08], p=0·0031) and asymptomatic plaques (1·49 [1·36–1·66], p=0·0012). 18 F-FDG TBR was also higher on the symptomatic side (1·68 [1·49–1·97] vs 1·51 [1·44–1·80], p=0·0081). The two PET tracers were moderately correlated ( r =0·40, p=0·0007). Coronary SST 2 signals were visible in all patients, but high myocardial muscle 18 F-FDG uptake was prohibitive in 27 patients (64%). Culprit coronary arteries had higher 68 Ga-DOTATATE TBR (2·91 [2·69–4·08]) than the highest non-culprit segment (2·61 [1·94–3·01], p=0·0078), stable stented (2·00 [1·51–2·70], p=0·0063), and calcified (1·64 [1·33–2·04], p 2 signal from culprit and high-risk coronary arteries was correlated with total cholesterol (r=0·44, p=0·042). Interpretation We have shown that measurement of vascular inflammation with SST 2 PET is feasible and differentiates high-risk and low-risk carotid and coronary lesions. High target specificity, low myocardial binding, and lower cost owing to generator-production give advantage to 68 Ga-DOTATATE over 18 F-FDG for atherosclerosis imaging. Correlations with 18 F-FDG TBR and serum cholesterol further support the vascular SST 2 signal as a potential prognostic biomarker to identify patients most at risk of future cardiovascular events. Funding Wellcome Trust.

Transcatheter aortic valve implantation in the young.

a Cardiovascular Sciences, Faculty of Medicine, National Heart and Lung Institute, Imperial College London, London, UK b Cardiology Department, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK c Radiology Department, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK d Renal and Transplant Department, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK