ECR_2015

www.totoku.eu The new CCL650i2 When size matters - 6 Megapixel - 30inch - 800cd/m² brightness LEDBACKLIGHT C M Y CM MY CY CMY K EUROPEAN HOSPITAL Vol 24 Issue 1/15 8 EH @ ECR New 3-D system quickens black-blood sequencing Seeking time-efficiency and high contrast Precisio Professor Hedvig Hricak MD PhD, Chair of the Department of Radiology at the Memorial Sloan- Kettering Cancer Centre, New York, and Professor of Radiology at Cornell University, Ithaca, New York, is a notable expert on cross- sectional anatomic and molecular imaging, particularly of gynaecologic and prostate cancers. John Brosky interviewed her about the potential and impact of more precise viewing of inter- and intra-tumoral heterogeneity Tobias Saam studied medicine at Heidelberg University where he also gained a doctorate in 2003. In July 2010 he wrote his habilitation on ‘Methodical Development and Clinical Evaluation of High Resolution MRI of Atherosclerotic Plaques in the Carotid Arteries’. Since 2006, Dr Saam has worked at the Institute for Clinical Radiology at the Ludwig Maximilian University (LMU) in Munich and has headed Magnetic Resonance Imaging since 2013. His numerous honours for work on MRI use to detect atherosclerotic plaques include the Coolidge Award. Report: Sascha Keutel Black Blood Imaging may not sound helpful – but it is. The MRI special- ist can work with clearer contrasts and gain greater certainty in tumour diagnosis as well as the detection of inflammatory changes in tissue. MRI procedures can be divided into those that show blood flow as bright (bright blood) and those that show it as dark (black blood). Although the latter method has numerous advantages compared to conventional imaging it is not yet used in clinical routine, according to Dr Tobias Saam, Head of Magnetic Resonance Imaging at the Inner City branch of the Institute for Clinical Radiology at the Ludwig-Maximilian University Munich. Black-blood sequences primar- ily visualise the actual walls of the blood vessels rather than blood flow. These sequences are routinely used for cardiac imaging and to identify artery dissections. However, they have great potential in imaging atherosclerotic plaques and inflam- matory changes in the vascular walls. Up to recent years, black-blood sequences could only be shown in 2-D, and running these was very complex. ‘It used to take us up to 40-50 seconds to visualise a sec- tion of the intracranial vessels of 2mm thickness. It took five to six minutes to acquire a small number of images. A new 3-D procedure, which we developed along with Philips Healthcare, now makes it possible to acquire images of the entire head, and with even better resolution, within the same space of time, so the procedure is now much more time efficient,’ Dr Saam explains. The procedure visualises significantly higher number of masses The new 3-D Black-Blood T1-TSE Sequence does not require pre- pulse for blood suppression and is therefore particularly time-effi- cient. In a first study on intracra- nial tumour imaging Saam’s team showed that the new procedure visualises a significantly higher number of masses compared to conventional sequences. ‘This new 3-D black-blood one Tesla sequence with variable flip angles allows us to detect more metasta- vessels,’ he adds. Advantages for the visual- isation of vascular walls Vasculitis is a comparatively rare disease often with unspecific clini- cal symptoms; its early detection poses a particular challenge for all clinicians. Vasculitides are primarily based on changes in the vascular walls. Diagnostic difficulty increas- es because any luminal changes detected are usually unspecific and they can also manifest as a result of other diseases. Therefore, the valid- ity of conventional imaging proce- dures is often limited. So far, the gold standard for imaging large vessel vasculitis has been PET-CT. However, Saam sees considerable advantages in the new procedure. ‘Black-blood technol- ogy enables us to directly visualise the vascular wall, to it’s possible to detect - at an early stage and with the help of contrast media - thickening of the walls, which can be evidence of atherosclerosis or inflammation of the vascular walls. Therefore we can use the procedure for direct imaging of inflammatory changes of intracranial as well as extracranial arteries.’ Black-blood imaging can reveal central nervous sys- tem (CNS) vasculitis The specialist cites central nerv- ous (CNS) system vasculitis as an example: ‘We cannot visualise this with other imaging procedures. In this case, black-blood imaging is the only procedure that makes this pos- sible. This capability has recently caused a lot of interest amongst neurologists,’ Saam points out. ‘Although this still has to be evalu- ated in larger studies, the procedure definitely has potential. ‘We are already having patients referred to us whose doctors are excited about it.’ Precision medicine in oncology offers tremendous potential and challenges. Are there obstacles? ‘Probably one of the greatest chal- lenges to the implementation of pre- cision medicine in oncology is the tremendous inter- and intra-tumoral genetic heterogeneity. The notions of inter- and intra-tumour heterogene- ity have been recognised for many years, but recent advances in sequenc- ing technology are allowing the true extent of both forms of heterogeneity to be revealed in detail. ‘Furthermore, sequential analysis of tumours has also revealed that intra-tumour heterogeneity tem- porally evolves during the disease course, which enables development of tumour resistance to therapies. Imaging has a tremendous potential to play in addressing this challenge, as it is the only tool that can examine biological heterogeneity both within an entire tumour and across multiple tumour deposits in the body, in vivo. ‘However, wide-spread use of imaging for this purpose will require tremen- dous further research, test-validation further combine with overcoming reg- ulatory hurdles to tracer development and approval, educating current and future radiologists to have a deeper understanding of molecular biology, and implementing bioinformatics on a much larger scale.’ You have said MRI has extensive untapped potential to contribute to molecularly-based precision medi- cine. Where is this being realised? ‘I’d like to point out that my comments are limited to the abdominal and pel- vic MR – as those are the areas of my expertise. Functional MRI techniques, such as dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI, are already providing prognostic, predictive, and early-response bio- markers that can be used to help determine the need for treatment, pre- 72-year-old patient with polymyalgia rheumatica and known giant-cell arteritis. Activity? A black-blood examination of the thorax clearly shows the vascular walls of the aorta as well as the supra-aortic vessels. After contrast medium administration there is clear evidence of contrast medium absorption along both subclavian arteries (arrowed). Synovitis in the right shoulder joint (right image*) is a secondary finding. Head MRI of patient with known small-cell bronchial carcinoma. The white arrows point towards three contrast-medium absorbing metastases, which are visible both in the 3-D-MPRAGE sequence as well as the 3-D black-blood sequence. The arrows point towards four additional lesions that can only be visualised in the 3-D black-blood sequence. A study carried out by our working group (Kammer N et al, RSNA 2014) demonstrated that the black-blood sequence detects considerably more metastases than the 3-D-MPRAGE sequence. 15-year-old patient with disseminated encephalomyelitis. MRI head scan of a 15-year- old patient with known Encephalomyelitis disseminata, or multiple sclerosis. The contrast medium enhanced image of the large lesion is shown both in the standard 3-D-MPRAGE sequence as well as a 3-D-Black-Blood Sequence (arrowed), although several of the white matter lesions detected in the FLAIR sequence show contrast medium absorption in the black-blood sequence that cannot be detected in the conventional sequence (circles). The existence of contrast medium absorption in these lesions shows the degree of disease activity and directly affects the patient’s clinical management. ses than with 3-D gradient echo sequences that are normally used for tumour detection. The differ- ence is significant. The procedure also has fewer flow artefacts than 2D-TSE sequences,’ Saam explains. ‘This is of clinical relevance because the earlier we can detect metastases or lesions the better we can treat them.’ A further effect of the new sequence: With conventionally used gradient sequences blood and lesions appear bright. The black- blood sequence shows masses/ lesions brightly, but not the blood, which is shown as dark. ‘This makes it easier to detect lesions, as there is less distraction from bright blood

ECR_2015

Pages Overview