Introducing our Aquilion ONE...ESC acquires a640 slice CT scanner 2 Imaging the Heart -Current Status ofCT Angiography 4 ...a view of the futureToshiba and ESC signResearch PartnershipAgreement 8 The European Scanning Centre Newsletter Special Edition
Welcome to this specialedition of Vision. ESC acquires a 640 slice CT scannerIt has been an exciting In order to continue to provide a first 7 years to develop and at a cost of more CTA from Aquilion ONEsummer for the ESC with class imaging service, the ESC has than £500 million. With its 16cm detector, a demonstrating (a) vulnerable softseveral major developments, recently acquired the world’s most five times the size of traditional 64-slice cholesterol rich plaque powerful CT scanner, the Toshiba CT scanners, and its innovative in RCA (arrow) and (b)the most important of which is Aquilion ONE™ 640 slice scanner, reconstruction algorithm, ConeExact, it its extent and degree of which has been installed alongside can reconstruct 640 slices per rotation, stenosis as analysed bythe installation of a new CT its EBCT scanner. giving unprecedented accuracy and the software (green =scanner, the Toshiba Aquilion detail. Its unique area of coverage normal patent lumen, blue/red = soft plaque. enables scanning of most organs withinONE 640 slice CT scanner. Dr Sarah Howling, one rotation, eliminating the need for Far right panels show the cross-sectionDespite the challenging ESC’s Director of Imaging helical scanning, which in turn, lowers the through the artery. comments: radiation dose dramatically (0.8 mSv foreconomic climate, we remain “I am seldom allowed to shop with such a CT angiogram compared to 2-3 for latitude! To create a dream list and then other scanners and 6-10 mSv forconvinced that medical succeed in securing the top CT scanner conventional angiograms).practitioners continue to need available in the world is more than I hoped for when I joined the ESC in 2005. The new scanner is likely to offerhigh quality diagnostic We selected the Toshiba scanner after numerous applications but in particularimaging. The Aquilion One is detailed evaluation of all the CT systems has significant advantages in cardiac, on the market. The Aquilion ONE is the neurological, musculoskeletal, oncologythe world’s most powerful top of the CT premier league and a huge and gastroenterology imaging. advance in technology. Our referringand advanced scanner and b doctors are going to be amazed by the Cardiac Imaging – CT angiographyprovides images of unrivalled images and applications this will offer.” Coronary CT angiography (CTA) issensitivity and spatial gaining increasing acceptance as a The Aquilion ONE is the world’s first viable alternative to invasive coronarydifferentiation. In addition to dynamic volume CT system, taking over angiography for selected patient groups. Its advantages are speed, minimal risk ofthe installation, the centre complications, and low morbidity.has undergone major However, its more widespread use is presently limited by concerns about therefurbishment with the long- spatial definition of current scanners,needed creation of a waiting including the EBCT scanner, and also the radiation dose to patients. The Aquilionroom. These developments ONE scanner overcomes these limitations and in particular its highwill ensure the ESC remains a temporal and spatial resolution allowsleading independent imaging detailed imaging of all of the coronary arteries, including the distal branches, ascentre and we look forward to well as clearly differentiating between softexploring the capabilities of and calcified plaque. This goal has been unachievable by conventional angiography.this remarkable machine. The proprietary software of the Aquilion2 The European Scanning Centre Newsletter
Feature Aquilion ONE 64 slice scanner scanners (including dual-source scanners) ‘a major role in Image acquisition per rotation 16 cm volume 3.2 cm cerebral blood acquisition flow imaging in Spatial resolution (mm) 0.3 0.5 patients at risk No. of rotations to image heart 1 8-10 of stroke’ Radiation dose for CT angiogram (mSv) 0.8 ≈2-3 Accurate imaging and quantification of Yes No Representative soft plaque images from dynamic Need for beta blockade No Yes Cerebral perfusion study in patient with imaging of a previous occipital infarct demonstrating wrist and knee ‘The Aquilion Able to scan patients with arrhythmias Yes No decreased perfusion (blue) during joint Dynamic imaging Yes No movement, ONE...allows allowing Perfusion studies Yes No elucidation of detailed imaging symptom Ability to image moving joints Yes No aetiology. of all of the coronary arteries,ONE also quantifies the extent of soft plaque data. Current studies are exploring the useburden as well as accurately assessing the of adenosine-induced tachycardia in the including thedegree of stenosis. Such imaging capabilities functional assessment of any stenosisare likely to transform the management of observed during the CT angiogram. distal branches,CHD by enabling practitioners to follow up joint symptoms which may be due to bone impingement, this is potentially an important as well as clearlythe progression of soft and calcified Neurologyatheromatous plaque and assess the response The ability of the Aquilion ONE to acquire application for sports injuries. differentiatingto aggressive preventive management. 16cm volumetric scans enables perfusion studies to be performed. The ESC has Cerebral CT angiogram demonstrating a Summary between soft andApart from its dramatic dose reduction, established close links with neurologists and In summary, the Aquilion ONE 640 slice CT large arteriovenous malformation (arrow) scanner represents a major advance in calcified plaque.another important aspect is the fact that neuroradiologists from the National Hospitalcardiac arrhythmia or heart rates up to 130 for Neurology and Neurosurgery and sees a scanning technology with unrivalled This goal has been “This scanner should provide high qualitybpm are no longer an issue as is frequently major role for the new scanner in cerebral sensitivity and spatial resolution. As such, it cerebral CT angiography, an imaging modalitythe case with helical 64 slice scanning, blood flow imaging in patients at risk of which is likely to supersede MRI angiography promises to offer both patients and unachievableincluding dual-source scanners. This is stroke. Its ability to perform high quality practitioners a viable non-invasive alternative and provide an alternative to invasive by conventionalbecause of the very fast speed of the image cerebral CT angiography will be clinically to many invasive diagnostic procedures, and angiography for many patients.”acquisition and the online assessment of the useful in the diagnosis and follow-up of with the added advantage of also being angiography.’imaged RR-interval by the new system’s carotid stenosis, arteriovenous malformations quicker and cheaper. However, we feel this is Musculoskeletalsoftware which ensures that image and aneurysms. just the start and with our talented The new scanner will for the first time alsoreconstruction can proceed as planned. radiography and radiologist team we are only allow imaging of joint kinematics,An exciting development of the Aquilion One Dr Paul Jarman, just beginning to consider its dynamic demonstrating moving joints in real timeis its unique ability to acquire volumetric consultant neurologist at the possibilities. It is an exciting time for all of us! (bone, ligaments and tendons by viewing inanalysis of the entire heart in one rotation National Hospital for Neurology different window width/levels). As staticwhich allows the acquisition of perfusion and Neurosurgery says: imaging often fails to elucidate the cause of 3
Imaging the Heart - Current Status of CT Angiography Dr Simon PG Padley The consequent reduction in scan times and Dr Nevin T Wijesekera renders images less susceptible to cardiac ‘an oral or Department of Radiology, dysrhythmias. Royal Brompton Hospital, Londonintravenous beta Spatial resolutionblocker is usually CT scanning has evolved hugely in the The coronary arteries measure from 4-5mm administered, past two decades. Improvements in in the left main stem to 1mm in the distal left speed and resolution have been so anterior descending artery. Sub-millimetre although not significant that it is now possible to spatial resolution with isotropic imaging (i.e. Prospective gating with Aquilion ONE CT angiogram scan. Imagerequired with 640 image structures as small and as rapidly equal resolution in all three planes) is acquisition occurs during single heart beat in late diastole, thereby significantly reducing radiation exposure slice scanners’ moving as the coronary arteries with desirable to delineate sub-millimetre temporal and spatial resolution coronary artery branches. In order to Only 180° of rotation is required for image In prospective approaching that of invasive coronary differentiate a 10-20% stenosis, isotropic generation, so temporal resolution is equal to gating, the angiography. spatial resolution of 0.3mm is considered half the gantry rotation speed. Current scan is ‘the experience necessary only achieved by the most up to technology has reduced a complete rotation triggered at a date scanners such as the Aquilion ONE. to 250ms. Ideally, a temporal resolution of specified point of both the 50ms is needed for coronary CT along the R-R radiographer Temporal resolution angiography (CTA) to cover all heart rates. interval, a short acquiring the The temporal resolution of a multi-detector However, with new reconstruction algorithms pulse of x-ray is delivered and then stops, to CT scanner is determined by the speed of and dual source scanners, a temporal recur at a similar time during the next cycle.images and the rotation of the gantry around the patient. resolution of 75ms is achievable. radiologist in In retrospective gating, data is acquired reporting them ECG gating continuously throughout the cardiac cycle, is crucial to the Images are typically acquired over a number allowing images to be later reconstructed at of cardiac cycles at time points when cardiac an appropriate percentage of the R-R quality of the motion is least, usually in late diastole (65% interval.images and thus to 85% of the R-R interval). This requires the final report’ acquisition of data to be synchronised with Radiation dose the cardiac cycle by reference to a Radiation doses in MDCT coronary simultaneously recorded ECG. angiography depends on a number of fixed Technical background and adjustable factors and now range from Successive generations of MDCT scanners The most commonly used ECG less than 1mSv to 5mSv on state of the art have rapidly evolved from 2 to 4, 8, 16, 32, synchronisation techniques for cardiac CT scanners, which is lower than invasive 40, 64, 128, 256 and now 320 rows of scanning are prospective ECG triggering coronary angiography (typically 6 – 10mSv). detectors (such as the Aquilion ONE). and retrospective ECG gating. The radiation exposure is higher when using 4 The European Scanning Centre Newsletter
retrospective ECG gating, compared with non-invasive visualisation of coronary Indications for CT angiography CTA vs conventional angiographyprospective imaging, because of the arteries with simultaneous evaluation of thecontinuous x-ray exposure and overlapping • Atypical chest pain pulmonary arteries, thoracic aorta, and other Advantagesdata acquisition. • Exclude coronary heart disease intra-thoracic structures that might explain • Non-invasive • Equivocal exercise stress test signs and symptoms that overlap with an • afer S ‘Aquilion ONE • oronary artery bypass graft C (no risk of local damage or stroke) acute coronary syndrome.CT Angiography: evaluation • Quicker - avoids day case admission promisesstep by step • Evaluate stent stenosis Plaque imaging • bility to visualise vulnerable soft A to be the • ardiac vein imaging to guide C plaque A number of studies have evaluated the ablation therapy • Visualise anomalous anatomy exceptionPremedication. If the heart rate is more ability of CT to distinguish between differentthan 65 beats/min, an oral or intravenous • Anomalous coronary artery anatomy types of atherosclerotic plaque, with the • omparable spatial resolution C with a • Congenital heart disease (0.3mm with 640 slice scanners)beta-blocker is usually administered, hope that this may help identify patients at • riple rule out (pulmonary, coronary T • Lower radiation reportedalthough not required with 640 slice elevated risk of future coronary events.scanners. Sublingual nitrates immediately and aortic angiogram) Plaques may be classified as calcified, • Cost - cheaper spatialbefore scanning help dilate the coronary mixed or soft, based on density Disadvantages (16-64 slice scanners) resolutionarteries. of haemodynamically relevant coronary measurement. The clinical application of • nable to scan arrhythmias U artery stenoses (50% luminal diameter coronary CTA for risk stratification based on (AF or high heart rate) of 0.3mm’Intravenous contrast delivery. A high reduction) using 16-slice and 64-slice CT. plaque characterisation is not yet supported • Lower spatial resolution (0.5 mm)concentration of contrast agent is injected Whilst the positive predictive value of MDCT by convincing scientific evidence but is an • rone to artefact from high coronary Pintravenously at a high flow rate (4-5mL/s) using 64-slice MDCT is relatively modest at area of much interest particularly with the artery calcium depositionfollowed by a 40-50ml saline chaser bolus to only 80-85%, the negative predictive value ability of the latest scanners to accurately • annot proceed to immediate Cwash out contrast from the right ventricle. approaches 100%, suggesting that CT can visualise and quantify the vulnerable soft therapeutic procedure reliably rule out the presence of significant cholesterol-rich plaque which may exist in e.g. angioplasty/ stent insertionPost-processing techniques. Analysis of coronary artery stenoses and makes the absence of calcification.the resultant enormous dataset is performed coronary CTA useful in symptomaticon dedicated powerful workstations. As with patients who are considered for invasive Bypass grafts assessmentall radiology, the experience of both the angiography but have a low-to-intermediate CT permits non-invasive assessment of theradiographer acquiring the images and the pre-test probability of coronary artery state of previous bypass grafts, includingradiologist in reporting them is crucial to the disease. This approach is currently favoured the anastamosis and the distal nativequality of the images and thus final report. in NICE guidelines (due to be published arteries. Several studies performed using early 2010). Patients whose clinical 16- and 64-slice MDCT have shown thatClinical applications of CT coronary presentation suggests a high likelihood of occlusion of bypass grafts and stenoses inangiography having a stenosis remain more likely to the body of the grafts can be detected withMDCT is now an established alternative to benefit from invasive angiography, which high accuracy. Native coronary arteries arecardiac catheterisation in the diagnosis of provides the option of immediate more difficult to assess since they maycoronary artery disease (CAD). Studies have intervention. become heavily calcified following bypassshown sensitivities of up to 97% and “Triple rule-out” coronary CT angiography is surgery making interpretation of stenosesspecificities as high as 94% for the detection a relatively new technique that provides difficult. This limits the clinical usefulness of 5
support the role of CT for routine follow-up cardiovascular magnetic resonance (CMR). of patients after coronary stent implantation, However, due to the relatively high radiation although more modern scanners have the dose, MDCT is currently not recommended‘CT can reliably potential to overcome this as they are less for the evaluation of cardiac function alone, rule out the affected by artefact and can offer clearer but these data are frequently available from images of the stent lumen. studies acquired for other primary presence of indications. CT also allows global cardiac significant Ventricular assessment assessment in patients unsuitable for MRI. Multiphase studies allow determination of coronary both end-diastolic and end-systolic volumes Myocardial perfusion artery using semi-automated software and hence An area of exciting current study is the use allow accurate calculation of stroke volume, of contrast-enhanced CT to visualise stenoses ejection fraction and cardiac output as well infarcted myocardium during first-pass and and makes as regional wall motion. There is good late perfusion imaging. Preliminary studies correlation between MDCT and cine assessing myocardial enhancement and coronary CTA of bypass grafts showing atheroma within the grafts (arrows) CTA useful in coronary CTA in patients who develop chest Cardiac function analysis of a patient with an anomalous LAD arising from RCA demonstrating reduced wall motion in the area from the anterior wall of the left ventricle to symptomatic pain after bypass surgery, as it usually will the apex (blue is reduced, green to red is normal). Image courtesy of Charité Hospital, Berlin using an Aquilion ONE scanner. be necessary to assess the status of both patients who the bypass grafts and the native coronary Wall Motion Wall Thickening Proportional Ejectionare considered arteries. When it is necessary to re-operate, Fraction MDCT can be critical in delineating the for invasive position of bypass grafts relative to the angiography sternum. but have Coronary stents low to Stent imaging is challenging due to the small size and high-density of stent material intermediate with resulting artefacts that can obscure the CTA of a patent stent in the LAD. Image pre test lumen. Accurate stent assessment depends acquired using Aquilion ONE 320 detector upon several factors, including stent type scanner. probability and material, stent dimensions (particularly of coronary the diameter) and the vessel in which the stent has been implanted. In-stent re-artery disease’ stenosis can be suggested when the lumen does not appear to completely enhance but current studies using 64 slice scanners have not yet provided conclusive evidence to6 The European Scanning Centre Newsletter
infarct size early after acute myocardialinfarction have shown good correlation gantry at approximately 90° to each other, producing faster scanning and temporal Our Radiologistsbetween MDCT and CMR. resolutions of 75ms, although they are unable to image the heart in one rotation. In order to further enhance the quality of our reportingCongenital anomalies of the exceptional images from the new scanner, we haveWhilst echocardiography and CMR imaging Summary recently recruited several additional specialist radiologists,remain the techniques of choice for the Computed tomography has advanced from many of the top institutions.assessment of patient with complex rapidly during the past years. Current MDCTcongenital heart disease, MDCT is now technology permits reliable and accurate Our team of radiologists with their NHS base and expertise is:emerging as a viable alternative to CMR visualisation of the coronary arteries. The(claustrophobia, pacemakers etc). MDCT technique is firmly established but recent Cardiaccoronary angiography can also be used to technological advances on a number of Dr Simon Padley, The Royal Brompton Hospitalidentify the course of anomalous coronary fronts are likely to improve the accuracy and Dr Paras Dalal, Harefield Hospitalarteries. reliability of CT for assessing coronary artery Dr Sujal Desai, King College Hospital disease and, if the expected reductions inDefining pulmonary vein anatomy radiation dose are achieved, the spectrum ChestCardiac CT is routinely employed in of accepted clinical indications willplanning of electrophysiological procedures, undoubtedly expand. Dr Sarah Howling, The Whittington Hospitalsuch as atrial fibrillation ablation since athree-dimensional CT image of the atria can Neurobe superimposed on the electro-anatomical Dr Katherine Miszkiel, National Hospital for Neurology Neurosurgerymap, improving the ability to localise the Dr Jane Evanson, Bart’s and The Londonpulmonary veins and hence reducefluoroscopy times. Abdomen/pelvisRecent technical developments Dr Chris Harvey, Hammersmith HospitalComputed tomography has gone through Dr Chris Schelvan, St Mary’s Hospitalrapid improvement during the last few years. Dr Niall Power, Bart’s and The LondonScanners with more detector rows allow agreater volume to be covered in one rotation Musculo-skeletalof the scanner, significantly reducing Dr Charles House, The Middlesex and UCL Hospitalbreath-hold time and amount of contrast. Dr Simon Bleese, full time privateThe latest 320-detector (640-slice) scannersincrease coverage and decrease overall Urologyscan time. Dual-source CT (DSCT) also Dr Jeevan Kumaradevan, The Whittington Hospitaloffers improvements in temporal resolution.These scanners have two sets of X-ray tubesand detectors, which are mounted onto the 7
European Scanning Centre Scans Aquilion ONE 640 slice CT scans AbdominalToshiba and ESC sign ESC completes Angiography (abdominal, carotid artery, cerebral, coronary,Research Partnership Agreement its makeover peripheral pulmonary) Brain Lung scan The building works at the ESC to accommodate the PelvicAs part of the collaboration between the ESC and Renal tract new scanner have resulted in a few additional changes.Toshiba Medical Systems, the two organisations have Gone is our old neon-lit office and now in its place is a Sinusesentered into a long-term Partnership Agreement. stylishly designed new waiting room, a huge Virtual colonoscopy improvement on the old corridor seating which patientsThe main features of this are: Electron Beam Computed previously had to endure! Top interior designer, Hugh Tomography (EBCT)• he ESC will become Toshiba’s UK reference site T Berry, has worked his magic again and given the room Heart scan (coronary artery and centre of excellence for CT imaging. a warm elegant feel but adding a hint of cosiness to calcium score) make clients feel relaxed both before and after their Bone mineral density• he ESC will be provided with all upgrades for the T scans. The lounge photographs on the wall are of new scanner for the duration of the agreement, Harley Street architecture and were taken by our Ultrasound thereby maintaining it at the cutting edge of consultant radiologist, Dr Sarah Howling whose love Abdomen Pelvis scanning technology. of digital imaging also extends to photography. Abdominal aorta• oshiba will support the ESC as an academic centre T Breast by jointly funding a Toshiba Research Fellow for a The refurbishments have also resulted in the creation Carotid Doppler minimum of 3 years. of a new ultrasound room as well as two large and Chest wall beautifully appointed consulting rooms. We are Shown here (left), Dr Paul Jenkins, Medical Gallbladder (static dynamic)Dr Matthew Stork, Managing Director, Director of ESC shaking hands on the agreement currently looking to occupy these by medical EchocardiographyToshiba Medical Systems UK says: with (right), Dr Matthew Stork, Managing Director, practitioners and if this is of potential interest, Female reproductive“Toshiba Medical Systems are delighted to Toshiba Medical Systems UK. please contact the centre on 020 7436 5755 for Fingerhave formed a partnership with the European further information. Leg veinsScanning Centre to work together on research The results of this research will be published in peerin this exciting new area. We have just started Neck reviewed journals and also presented at national andexploring the benefits of dynamic volume CT. international scientific meetings. Penile DopplerWhether it is for cardiac, neuro, abdominal, Post micturition bladderorthopaedic or other examinations, the potential Dr Paul Jenkins, Medical Director of ESC says: Prostate (trans-abdominal implications of functional CT studies are trans-rectal) “We are very excited about our partnership withwidespread. The European Scanning Centre is Toshiba and in becoming their UK reference site. Renal arteryan ideal partner for us, working with leading The establishment of a Toshiba Research Fellow Renal tractacademics across many therapeutic areas will allow us to further our aim of becoming an Urinary flow rate measurementproviding a broad scope for research.” academic centre and we look forward to Testes developing our clinical applications with the new Thyroid GlandThe Research Fellow will be based at the ESC and will scanner, particularly the role of CT angiography We offer a complete X-ray andcarry out research in a number of agreed areas - for in both cardiac and cerebral studies as well as MRI serviceexample myocardial and cerebral perfusion. functional perfusion studies.” European Scanning Centre • 68 Harley Street • London W1G 7HE • Tel: 020 7436 5755 • Fax: 020 7436 5756 • www.europeanscanning.com
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