IN VIVO PROTON MR SPECTROSCOPY OF GLIOMATOSIS CEREBRI: DIAGNOSIS AND EXPLORATION OF TUMOR METABOLISM E.D. Gotsis a,* , D.S. Gkotsi b , G. Pissakas c , I. Seimenis d a Institute Euromedica-Encephalos, Halandri, Greece b Univeristy of St Andrews, Department of Chemistry, St Andrews, Scotland, United Kingdom c General Hospital ”Alexandra”, 2nd Oncologic Clinic, Athens, Greece d Democritus University of Thrace, Medical School, Medical Physics Laboratory, Alexandroupolis, Greece ⇑ Corresponding author. Introduction. Gliomatosis cerebri was not recognised as a sepa- rate entity till a few years ago and it was thought to be a rare entity. Advanced imaging methods and In Vivo Proton MR spectroscopy (MRS) have contributed to the safe diagnosis of the disease, which is not such a rare entity as once thought. Purpose. To explore the capabilities of In Vivo Proton MR Spec- troscopy not only for diagnosing the disease but also for exploring the metabolism of the tumor cells. Materials and methods. In an extended period of 16 years, 147 patients were diagnosed with gliomatosis cerebri by In Vivo MR Spectroscopy (single voxel at selected areas and 3D Spectroscopic Imaging). Metabolic maps of choline and creatines showed tumor infiltration. For some patients serial MRS was also performed. Results. In virtually all cases except one – a patient diagnosed with gliomatosis cerebri for whom the biopsy showed limbic encephalitis – biopsy confirmed a ”glioma” or in cases without biopsy the progress of the disease confirmed the MRS diagnosis. What was a surprise was that in most cases creatine concentration was higher than normal leading to the notion that part of the tumor cells maintain for some time normal cell metabolism (aerobic glycol- ysis). With advance of time, the metabolism switches to the primi- tive tumor cell metabolism. Conclusion. In Vivo Proton MR Spectroscopy is a potent probe for the diagnosis of gliomatosis cerebri as well as for exploring tumor cell metabolism. Disclosure. None of the authors has anything to declare. http://dx.doi.org/10.1016/j.ejmp.2016.07.525 TREATMENT PLAN VERIFICATION IN MRGFUS FOR BONE METASTASIS PAIN PALLIATION D. Bianchini * , F. Marcocci, E. Menghi, V. D’Errico, E. Mezzenga, A. Sarnelli Medical Physics Department, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola (FC), Italy ⇑ Corresponding author. Introduction. Focused ultrasound are recently introduced as alternative therapy for pain palliation caused by bone metastases. The heat absorption and propagation in the soft tissues and in the bones strongly depends on the correct focalization of the ultrasonic beam through the interfaces. The real-time thermal map provided by the MRI gives to the interventional radiologist the feedback for the online treatment planning. Purpose. The present work is focused on the verification of plan- ning therapy system of a MRgFUs system giving a verification of the propagation and the accumulation of the temperature in bones in particular for the pelvic bone. Materials and methods. In this work it has been studied the Philips Sonalleve HIFU installed on Ingenia 3T. The thermal maps has been studied on a multi-interface phantom with albumin-agarose gel volu- metric detector. The planned volume ablation temperature has been compared with the T2 imaging modification on the phantom. A dedi- cated software has been developed for the extraction of the thermal image maps from the system and for the evaluation of the cumulative thermal dose. A first approach has been proposed for the evaluation of the plan in term of DVH (dose/volume histogram). Results. High impedance interfaces create local depositions of energy along the sonicated surfaces. The plan cumulative dose veri- fication gives constraints to the physicians on sonication cells positioning. Conclusion. The MRgFUs feedback planning gives partial informa- tion of the heat deposition. The bone phantom is used to evaluate the real cells volume. The de-focalization created by bones demonstrate the needs of preplanning system dedicated to bones treatments. http://dx.doi.org/10.1016/j.ejmp.2016.07.526 A METHOD FOR FAST 3D IMAGING OF CONTRAST ENHANCED VESSELS OR CATHETERS USING MAGNETIC RESONANCE PROJECTIONS M. Unan a , I. Seimenis b,* , A.G. Webb c , N.V. Tsekos a a Medical Robotics Laboratory, Dept of Computer Science, University of Houston, Houston, TX, USA b Democritus University of Thrace, Medical School, Medical Physics Laboratory, Alexandroupolis, Greece c C.J. Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, Netherlands ⇑ Corresponding author. Introduction. With a plethora of soft-tissue contrast mechanisms, lack of ionizing radiation and on-the-fly computer controller adjust- ment of imaging parameters, MRI has emerged as an alternative modality for guiding interventions. However, due to its inherent low signal sensitivity, conventional MRI cannot achieve the high speeds of X-ray fluoroscopy. Purpose. To address this, we describe a novel approach for 3D MRI of tubular structures such as blood vessels or catheters, based on the collection of thick slab spatially matched projections. Materials and methods. The implemented method includes the following: three elements. (1) Collection of three orthogonal projec- tions of the same volume that contains the structure with a GRE (TR/ TE = 26.07/3.71 ms, angle = 75°, matrix = 256 Â 256, FOV = 200 Â 200 mm 2 , slice = 200 mm). (2) Segmentation of the 2D structures on the three projections. (3) Reconstruction of the 3D structure by back projection. The method was tested on phantoms with vessel- mimicking structures made of tubing filled with 2% Gd-agent in a fatty matrix. The ground truth was an MRA (128 slices, TR/ TE = 3.8/1.52 ms, angle = 40°, matrix = 384 Â 264, FOV = 191 Â 131 mm 2 , slice = 1.3 mm). Results. The 3D centerline of the rendered structures was extracted and then found to be virtually the same (±pixel) to this extracted from a multislice MRA of the same structure. Conclusion. The method can accurately image 3D tubular object in 20 s as compared to 186 s with the used MRA. Disclosure. None of the authors has anything to declare. http://dx.doi.org/10.1016/j.ejmp.2016.07.527 ASSESSMENT OF TOTAL GEOMETRIC DISTORTION IN MR IMAGES USED IN INTRACRANIAL STEREOTACTIC RADIOSURGERY Mukhtar Alshanqity a , Eleftherios P. Pappas b,* , Pantelis Karaiskos b , Argyris Moutsatsos b , Khalid Alsafi a , Hani Lababidi a , Evangelos Georgiou b a King Fahad Medical City, Riyadh, Saudi Arabia 248 Abstracts / Physica Medica 32 (2016) 222–250