Ashley Wachsman

Four-Dimensional Magnetic Resonance Imaging With 3-Dimensional Radial Sampling and Self-Gating-Based K-Space Sorting: Early Clinical Experience on Pancreatic Cancer Patients.

PURPOSE To apply a novel self-gating k-space sorted 4-dimensional MRI (SG-KS-4D-MRI) method to overcome limitations due to anisotropic resolution and rebinning artifacts and to monitor pancreatic tumor motion. METHODS AND MATERIALS Ten patients were imaged using 4D-CT, cine 2-dimensional MRI (2D-MRI), and the SG-KS-4D-MRI, which is a spoiled gradient recalled echo sequence with 3-dimensional radial-sampling k-space projections and 1-dimensional projection-based self-gating. Tumor volumes were defined on all phases in both 4D-MRI and 4D-CT and then compared. RESULTS An isotropic resolution of 1.56 mm was achieved in the SG-KS-4D-MRI images, which showed superior soft-tissue contrast to 4D-CT and appeared to be free of stitching artifacts. The tumor motion trajectory cross-correlations (mean ± SD) between SG-KS-4D-MRI and cine 2D-MRI in superior-inferior, anterior-posterior, and medial-lateral directions were 0.93 ± 0.03, 0.83 ± 0.10, and 0.74 ± 0.18, respectively. The tumor motion trajectories cross-correlations between SG-KS-4D-MRI and 4D-CT in superior-inferior, anterior-posterior, and medial-lateral directions were 0.91 ± 0.06, 0.72 ± 0.16, and 0.44 ± 0.24, respectively. The average standard deviation of gross tumor volume calculated from the 10 breathing phases was 0.81 cm(3) and 1.02 cm(3) for SG-KS-4D-MRI and 4D-CT, respectively (P=.012). CONCLUSIONS A novel SG-KS-4D-MRI acquisition method capable of reconstructing rebinning artifact-free, high-resolution 4D-MRI images was used to quantify pancreas tumor motion. The resultant pancreatic tumor motion trajectories agreed well with 2D-cine-MRI and 4D-CT. The pancreatic tumor volumes shown in the different phases for the SG-KS-4D-MRI were statistically significantly more consistent than those in the 4D-CT.

Dosimetric evaluation of simultaneous integrated boost during stereotactic body radiation therapy for pancreatic cancer

Stereotactic body radiation therapy (SBRT) provides a promising way to treat locally advanced pancreatic cancer and borderline resectable pancreatic cancer. A simultaneous integrated boost (SIB) to the region of vessel abutment or encasement during SBRT has the potential to downstage otherwise likely positive surgical margins. Despite the potential benefit of using SIB-SBRT, the ability to boost is limited by the local geometry of the organs at risk (OARs), such as stomach, duodenum, and bowel (SDB), relative to tumor. In this study, we have retrospectively replanned 20 patients with 25Gy prescribed to the planning target volume (PTV) and 33~80Gy to the boost target volume (BTV) using an SIB technique for all patients. The number of plans and patients able to satisfy a set of clinically established constraints is analyzed. The ability to boost vessels (within the gross target volume [GTV]) is shown to correlate with the overlap volume (OLV), defined to be the overlap between the GTV + a 1(OLV1)- or 2(OLV2)-cm margin with the union of SDB. Integral dose, boost dose contrast (BDC), biologically effective BDC, tumor control probability for BTV, and normal tissue complication probabilities are used to analyze the dosimetric results. More than 65% of the cases can deliver a boost to 40Gy while satisfying all OAR constraints. An OLV2 of 100cm(3) is identified as the cutoff volume: for cases with OLV2 larger than 100cm(3), it is very unlikely the case could achieve 25Gy to the PTV while successfully meeting all the OAR constraints.

The effects of everolimus on tuberous sclerosis-associated lesions can be dramatic but may be impermanent

BackgroundTuberous sclerosis complex (TSC) predisposes to the development of benign lesions within multiple organ systems, including the brain, kidneys, heart, lungs, and skin. Disease mortality is due to space-occupying subependymal giant cell astrocytomas and hemorrhage-prone renal angiomyolipomas. The recent use of mTORC1 inhibitors, such as everolimus, has allowed for direct targeting of TSC-associated mass lesions without apparent effect on surrounding tissues. Because of the mechanism of these drugs, there is reason to believe that these effects are not durable and that there may be need for continued long-term maintenance therapy.Case-diagnosis/treatmentWe present a case of TSC-associated mass lesions that were ill-suited for definitive surgical therapy. The patient was started on everolimus, however due to a complex social situation treatment was discontinued and ultimately resumed many months later. Radiologic studies acquired before and after each period of therapeutic onset/cessation reveal the dramatic but impermanent effects of mTORC1 inhibition.ConclusionsWhile everolimus provides a non-invasive way to treat TSC-associated lesions, patients may require lifelong therapy. When termination of therapy is considered, the patient should be made aware of the expectation of potentially dramatic increases in lesion size. If consideration is to be given to definitive surgical therapy, it should be pursued while the patient is still on the medication, or at least soon after treatment is halted.

Imaging of Neuroendocrine Tumors: Indications, Interpretations, Limits, and Pitfalls

Imaging is critical in the diagnosis, prognosis, and management of neuroendocrine tumors (NETs). NETs share common imaging features, but each type exhibits unique features. Computed tomography scans or MRI of the abdomen is used to assess tumor burden routinely. Functional imaging with octreotide scan or gallium-68 somatostatin analog PET is used selectively to confirm diagnosis and guide therapy. Clinicians and radiologists should be familiar with the indications and interpretations of imaging modalities. Novel functional imaging modalities likely will be developed to detect small NETs, predict prognosis, guide therapeutic choices, and design novel therapies.

Su1116 Small Bowel Ultrasound Accurately Predicts Post-Operative Endoscopic Recurrence in Crohn's Disease

Background & Aim: Recently, mucosal healing assessed by endoscopic findings appears to predict long-term remission in patients with ulcerative colitis (UC), although there is no agreement on clinical, endoscopic or histological scoring system. In most of clinical trial, endoscopic score of Mayo 0 or 1 is defined as mucosal healing in UC patients. However, assessment of endoscopic score of Mayo 0 or 1 is quite different depending on endoscopists. Therefore, to develop the objectively quantitative scoring system that will help to improve patient outcome is required. Emerging endoscopic imaging modalities, including both, vital and virtual chromoendoscopy and magnification endoscopy, enabled endoscopists to visualize and interpret mucosal details. Among them, i-scan is the newly developed imageenhanced endoscopic technology from HOYA/PENTAX (Tokyo, Japan). i-scan TE-c is one of digital transmission method among HOYA/PENTAX EPK-i system in conjunction with EC38-i10M. The aim of study is to assess the significance of new endoscopic imaging system with i-scan TE-c for quantitative evaluation of colonic inflammation in patients with UC. Method: From January 2011 to Aug 2012, a total of 76 UC patients with endoscopic score of Mayo 0 or 1 by standard white light endoscopy were reassessed by i-scan TE-c. We performed white light (WL) colonoscopy in conjunction with i-scan TE-c in UC patients with endoscopic score of Mayo 0 or 1, and the difference of the tone of color between normal and inflamed colonic mucosa was given with a numeric conversion. The intensity and width of inflammatory lesion identified by modified color phase and saturation was given with a numeric conversion and visualized. Results: In 29 of 76 UC patients, endoscopic score of Mayo was estimated as 0. In the remaining 47 patients, that was estimated as 1. The mean i-scan TE-c score of UC patients with endoscopic score of Mayo 0 and with Mayo 1 was 576.1±437.3 and 1172.7±668.6, respectively. A significant difference of i-scan TE-c score was observed between UC patients with endoscopic score of Mayo 0 and those with Mayo 1 (p,0.001). There was a considerable variation in i-scan TE-c score of UC patients with endoscopic score of Mayo 1 by WL colonoscopy, suggesting that UC patients diagnosed with endoscopic score of Mayo 1 had intestinal inflammation with objectively varying degrees. Conclusion: In UC patients with endoscopic score of Mayo 0 or 1, this new imaging system with i-scan TE-c can make the inflammatory lesion visualized more clearly in comparison with WL colonoscopy, and their intensity and width digitized. Application with this new system is easy and useful for objective and quantitative evaluation of colonic inflammation in UC patients with endoscopic score of Mayo 0 or 1. Further clinical trial with a new imaging system will be required for clinically quiescent UC patients.

The role of pre-operative imaging and double balloon enteroscopy in the surgical management of small bowel neuroendocrine tumors: Is it necessary?

Pre‐operative localization of small bowel neuroendocrine tumors (SBNET) is important for operative planning. The aim was to determine the effectiveness of pre‐operative imaging and double‐balloon enteroscopy (DBE) in identifying extent of disease.

TH‐CD‐204‐01: FEATURED PRESENTATION and BEST IN PHYSICS (JOINT IMAGING‐THERAPY): Novel SG‐KS‐4D‐MRI Sequence Reduces 4D Rebinning Artifacts and Improves GTV Contouring Consistency for Pancreatic Cancer Patients

Purpose: Dynamic magnetic resonance imaging (MRI) has been used to characterize tumor motion but real time acquisition has been limited to 2-dimensions. Methods have been developed to reconstruct four-dimensional MRI (4D-MRI) based on time-stamped 2D images or 2D K-space data. These methods suffer from anisotropic resolution and rebinning artifacts. We have developed a self-gating based K-space sorted 4D-MRI (SG-KS-4D-MRI) method to overcome these limitations and in this study apply it to monitoring organ motion of pancreatic cancer patients. Methods: Ten patients were imaged using 4D-CT, cine 2D-MRI and the SG-KS-4D-MRI method, which is a spoiled gradient recalled echo (GRE) sequence with 3D radial-sampling K-space projections and 1D projection-based self-gating. Tumor volumes were drawn at the end of exhalation phases in the 4D-MRI and 4D-CT, and mapped to the other phases using deformable registration. The tumor volumes and motion trajectories were compared. Results: An isotropic resolution of 1.6 mm was achieved in the SG-KS-4D-MRI images, which showed superior soft tissue contrast to 4D-CT and appeared to be free of rebinning artifacts. SG-KS-4D-MRI was able to detect out-of-plane tumor motion and showed good correlation with 4D-CT and cine 2D-MRI in superior-inferior direction with a correlation coefficient of 0.91±0.06 and 0.93±0.03, respectively. The average standard deviation of GTV (GTV_σ) calculated from ten breathing phases were 0.81 cc and 1.02 cc for SG-KS-4D-MRI and 4D-CT (p=0.004) respectively. Conclusion: A novel SG-KS-4D-MRI acquisition method capable of reconstructing rebinning-artifact-free high resolution 4D-MRI images was used to quantify pancreas tumor motion. The resultant pancreatic tumor motion trajectories better agreed with 2D-cine-MRI and 4D-CT in the SI direction than the other 2 directions due to smaller motions in those directions. The pancreatic tumor volumes derived using SG-KS-4D-MRI were significantly more consistent than those from the 4D-CT.This work is supported in part by NIH grant 1R03CA173273-01. This study is supported in part by NIH 1R03CA173273