Continuous real time 3D motion reproduction using dynamic MRI and precomputed 4DCT deformation fields.

Radiotherapy of mobile tumors requires specific imaging tools and models to reduce the impact of motion on the treatment. Online continuous nonionizing imaging has become possible with the recent development of magnetic resonance imaging devices combined with linear accelerators. This opens the way to new guided treatment methods based on the real-time tracking of anatomical motion. In such devices, 2D fast MR-images are well-suited to capture and predict the real-time motion of the tumor. To be used effectively in an adaptive radiotherapy, these MR images have to be combined with X-ray images such as CT, which are necessary to compute the irradiation dose deposition. We therefore developed a method combining both image modalities to track the motion on MR images and reproduce the tracked motion on a sequence of 3DCT images in real-time. It uses manually placed navigators to track organ interfaces in the image, making it possible to select anatomical object borders that are visible on both MRI and CT modalities and giving the operator precise control of the motion tracking quality. Precomputed deformation fields extracted from the 4DCT acquired in the planning phase are then used to deform existing 3DCT images to match the tracked object position, creating a new set of 3DCT images encompassing irregularities in the breathing pattern for the complete duration of the MRI acquisition. The final continuous reconstructed 4DCT image sequence reproduces the motion captured by the MRI sequence with high precision (difference below 2 mm).

Is early enteral nutrition dangerous in acute non surgical complicated diverticulitis? About 25 patients fed with oral fiber free energetic liquid diet.

BACKGROUND AND STUDY AIMS: Complicated Acute Colonic Diverticulitis (ACD) is usually treated by parenteral way thus keeping the bowel at rest. To date there are no clear recommendations regarding the route of nutrition administration. We study the safety of early feeding by oral energetic fiber-free liquid diet in non-surgical complicated ACD patients. PATIENTS AND METHODS: From February 2008 to October 2011, 25 patients were admitted with complicated ACD and took part in this prospective study. Surgical and medical assessments were performed at admission. Initial treatment was given with perfusion, intravenous antibiotics and hydric diet. Within 72 hours of admission, antibiotic therapy was switched to oral administration for 5 up to 15 days depending on the progression of the disease. At the same time the patient received oral liquid fiber-free feeding. Solid but fiber-free diet was introduced 24h hours before discharge. RESULTS: 25 cases of ACD were complicated with covered perforation and/or abscess. Mean hospitalisation time was 10A.4 days. 23 cases had good recovery and discharged, while 1 case progressed to colonic stenosis during hospitalisation, requiring a sigmoidectomy with a one-time anastomosis with good recovery. One patient relapsed his abscess during hospitalisation despite CT guided drainage and required sigmoidectomy with transient ileostomy. The mean daily treatment and nutrition cost for the non-surgical 23 patients was 30 euros. CONCLUSIONS: Early enteral nutrition in complicated ACD is feasible, not harmful, and reduce both, mean hospitalization time and treatment cost. Further studies comparing enteral with parenteral nutrition are necessary to confirm our hypothesis.