Radiation dose reduction in pediatric great vessel stent computed tomography using iterative reconstruction: A phantom study

Background To study dose reduction using iterative reconstruction (IR) for pediatric great vessel stent computed tomography (CT). Methods Five different great vessel stents were separately placed in a gel-containing plastic holder within an anthropomorphic chest phantom. The stent lumen was filled with diluted contrast gel. CT acquisitions were performed at routine dose, 52% and 81% reduced dose and reconstructed with filtered back projection (FBP) and IR. Objective image quality in terms of noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as subjective image quality were evaluated. Results Noise, SNR and CNR were improved with IR at routine and 52% reduced dose, compared to FBP at routine dose. The lowest dose level resulted in decreased objective image quality with both FBP and IR. Subjective image quality was excellent at all dose levels. Conclusion IR resulted in improved objective image quality at routine dose and 52% reduced dose, while objective image quality deteriorated at 81% reduced dose. Subjective image quality was not affected by dose reduction

Baseline MDCT findings after prosthetic heart valve implantation provide important complementary information to echocardiography for follow-up purposes

Objectives: Recent studies have proposed additional multidetector-row CT (MDCT) for prosthetic heart valve (PHV) dysfunction. References to discriminate physiological from pathological conditions early after implantation are lacking. We present baseline MDCT findings of PHVs 6 weeks post implantation. Methods: Patients were prospectively enrolled and TTE was performed according to clinical guidelines. 256-MDCT images were systematically assessed for leaflet excursions, image quality, valve-related artefacts, and pathological and additional findings. Results: Forty-six patients were included comprising 33 mechanical and 16 biological PHVs. Overall, MDCT image quality was good and relevant regions remained reliably assessable despite mild-moderate PHV-artefacts. MDCT detected three unexpected valve-related pathology cases: (1) prominent subprosthetic tissue, (2) pseudoaneurysm and (3) extensive pseudoaneurysms and valve dehiscence. The latter patient required valve surgery to be redone. TTE only showed trace periprosthetic regurgitation, and no abnormalities in the other cases. Additional findings were: tilted aortic PHV position (n = 3), pericardial haematoma (n = 3) and pericardial effusion (n = 3). Periaortic induration was present in 33/40 (83 %) aortic valve patients. Conclusions: MDCT allowed evaluation of relevant PHV regions in all valves, revealed baseline postsurgical findings and, despite normal TTE findings, detected three cases of unexpected, clinically relevant pathology. Key Points: • Postoperative MDCT presents baseline morphology relevant for prosthetic valve follow-up. • 83 % of patients show periaortic induration 6 weeks after aortic valve replacement. • MDCT detected three cases of clinically relevant pathology not found with TTE. • Valve dehiscence detection by MDCT required redo valve surgery in one patient. • MDCT is a suitable and complementary imaging tool for follow-up purposes

Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging?

__Background:__ Complications might occur after great vessel stent implantation in children. Therefore follow- up using imaging is warranted. __Purpose:__ To determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children. __Material and methods:__ Five different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1), placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RFspoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D seq

Surgically implanted aortic valve bioprostheses deform after implantation: insights from computed tomography

Objective: Little is known about the prevalence and degree of deformation of surgically implanted aortic biological valve prostheses (bio-sAVRs). We assessed bio-sAVR deformation using multidetector-row computed tomography (MDCT). Methods: Three imaging databases were searched for patients with MDCT performed after bio-sAVR implantation. Minimal and maximal valve ring diameters were obtained in systole and/or diastole, depending on the acquired cardiac phase(s). The eccentricity index (EI) was calculated as a measure of deformation as (1 − (minimal diameter/maximal diameter)) × 100%. EI of 10% non-circular. Indications for MDCT and implanted valve type were retrieved. Results: One hundred fifty-two scans of bio-sAVRs were included. One hundred seventeen measurements were performed in systole and 35 in diastole. None or trivial deformation (EI 5%) in 56% of studied cases and were considered non-circular (eccentricity index > 10%) in 17% of studied valves. • The higher deformity rate found in bio-sAVRs with (suspected) valve pathology could suggest that geometric deformity may play a role in leaflet malformation and thrombus formation similar to that of transcatheter heart valves

Role of CT in patients with prosthetic heart valves

Valvular heart disease accounts for a substantial part of the cardiovascular disease worldwide with an estimated prevalence of 2.5% in the Western population aged 75 years. Surgical prosthetic heart valve (PHV) replacement is the indicated therapy for severe valve disease or in symptomatic patients. PHV-related complications are serious and potentially life threatening and include structural valve deterioration, regurgitation, endocarditis and obstruction. Acquired PHV obstruction is mostly caused by valve thrombosis or pannus (fibrous subprosthetic tissue), whereas valve obstruction presenting early after implantation may be caused by patient prosthesis mismatch. Depending on the cause and severity of dysfunction, the treatment may include antibiotic therapy, anticoagulant therapy, fibrinolysis, redo valve surgery or valve-in-valve implantation and is associated with high morbidity and mortality. Hence, baseline and follow-up imaging after PHV implantation is important to detect and differentiate between these complications and to determine the correct treatment strategy. Transthoracic echocardiography (TTE) is the routine diagnostic imaging modality. In addition, transesohageal echocardiography (TEE) and fluoroscopy may be considered in suspected PHV dysfunction. Although echocardiography is readily available and provides functional information, it may result in an inconclusive diagnostic work-up as it often cannot detect the underlying cause of PHV dysfunction. In this thesis the role of computed tomography (CT) as diagnostic imaging modality in addition to routine work-up in patients with PHVs was evaluated. Presented in vitro results show that compared with fluoroscopy, CT can accurately assess mechanical valve leaflet excursions and detect leaflet restriction. Although the effective radiation dose of retrospectively ECG-gated CT acquisitions may be a drawback, modern iterative reconstruction techniques allow for dose reduction while maintaining good image quality. In patients, CT performed at baseline after PHV implant detected pathology that was not detected with routine TTE imaging including pseudoaneuryms, valve dehiscence and subprosthetic tissue. In suspected PHV dysfunction, additional CT imaging provided complementary information to echocardiography on the underlying cause of PHV dysfunction by detecting subvalvular membrane, pannus and/or thrombus. In mechanical PHVs, CT also resulted in a change of the treatment strategy in a third of patients. In biological valves. CT can be used to detect valve calcifications in (early) structural valve deterioration. In patients with suspected PHV regurgitation, the strength of complementary CT is its ability to detect or exclude infectious complications in both mechanical and biological valves. Furthermore, CT showed relevant for planning redo surgery and percutaneous periprosthetic leak closure as it provides information on PHV-related anatomy, implanted PHV size and can be used for concomitant evaluation of coronary artery stenosis and transcatheter (valve-in-valve) sizing. In conclusion, CT as additional imaging modality has incremental value to echocardiography and fluoroscopy and provides complimentary, readily available information helpful for planning redo surgery or transcatheter procedures. CT should therefore always be considered in all patients with suspected PHV dysfunction and may be considered in selected patients at baseline after PHV implant

Sublingual Nitroglycerin Administration in Coronary Computed Tomography Angiography : a Systematic Review

To systematically investigate the literature for the influence of sublingual nitroglycerin administration on coronary diameter, the number of evaluable segments, image quality, heart rate and blood pressure, and diagnostic accuracy of coronary computed tomography (CT) angiography. A systematic search was performed in PubMed, EMBASE and Web of Science. The studies were evaluated for the effect of sublingual nitroglycerin on coronary artery diameter, evaluable segments, objective and subjective image quality, systemic physiological effects and diagnostic accuracy. Due to the heterogeneous reporting of outcome measures, a narrative synthesis was applied. Of the 217 studies identified, nine met the inclusion criteria: seven reported on the effect of nitroglycerin on coronary artery diameter, six on evaluable segments, four on image quality, five on systemic physiological effects and two on diagnostic accuracy. Sublingual nitroglycerin administration resulted in an improved evaluation of more coronary segments, in particular, in smaller coronary branches, better image quality and improved diagnostic accuracy. Side effects were mild and were alleviated without medical intervention. Sublingual nitroglycerin improves the coronary diameter, the number of assessable segments, image quality and diagnostic accuracy of coronary CT angiography without major side effects or systemic physiological changes. aEuro cent Sublingual nitroglycerin administration results in significant coronary artery dilatation. aEuro cent Nitroglycerin increases the number of evaluable coronary branches. aEuro cent Image quality is improved the most in smaller coronary branches. aEuro cent Nitroglycerin increases the diagnostic accuracy of coronary CT angiography. aEuro cent Most side effects are mild and do not require medical intervention