Delineation and Visualization of Prostate Cancer for Targeted Radiation Therapy (Rt)
Radka Stoyanova¹, Raj Rajpara¹, Elizabeth Bossart¹, Victor Casillas², Jill Palma¹, May Abdel-Wahab¹, Alan Pollack^1
1Radiation Oncology, University of Miami, Miami, FL, United States; ²Diagnostic Radiology, University of Miami, Miami, FL, United States

We present an application of Pattern Recognition technique for analysis of DCE-MRI data from patients with prostate cancer and after prostatectomy. Our analysis indicates that we can detect the area of tumor burden in the prostate as well as abnormalities suggestive of residual/recurrent tumor in the prostate bed. The constructed 3D maps can be directly imported into DICOM-RT ready format to the RT planning system for targeting of the contrast enhancing areas specifically in order to improve tumor control and limit toxicity.

A Study of Endorectal MRI and MRSI of the Prostate as Predictive Biomarkers of Biochemical Relapse After Radical Prostatectomy
Kristen Zakian¹, Hedvig Hricak², Nicole Ishill³, Victor Reuter⁴, Steven Eberhardt⁵, Chaya Moskowitz³, Amita Shukla-Dave, Liang Wang, Peter Scardino⁶, James Eastham, Jason Koutcher
¹Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, United States; ²Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States; ³Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, United States; ⁴Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States;  ⁵Radiology, University of New Mexico, Albuquerque, NM, United States; ⁶Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, United States

The purpose of this study was to determine whether pre-treatment endorectal MRI/MRSI can predict biochemical relapse (BCR)  after radical prostatectomy (RP). 130 of 202 patients who underwent endorectal MRI/MRSI in 2000-2002 followed by RP satisfied data quality criteria and were followed until Jan. 2009. MRI risk score was assigned based on local disease extent.  An MRSI index lesion comprised of voxels with elevated [Cho+Cr]/Cit volume was designated. MRI risk score, MRSI index lesion volume and the presence of high grade MRSI voxels correlated with time-to-biochemical failure after radical prostatectomy even when adjusted for clinical stage, biopsy Gleason score and PSA.

3D Proton MR Spectroscopic Imaging of Prostate Cancer: Accuracy Evaluation in Different Prostate Regions
Stefan Zbyn^1,2, Martin Krssak², Mazda Memarsadeghi², Klaus Kubin², Andrea Haitel³, Michael Weber², Thomas Helbich², Ewald Moser¹, Siegfried Trattnig^1,2, Stephan Gruber^1,2
1MR Centre of Excellence, Medical University of Vienna, Vienna, Austria; ²Department of Radiology, Medical University of Vienna, Vienna, Austria; ³Department of Pathology, Medical University of Vienna, Vienna, Austria

Since spectral quality of prostate 3D-MRSI data vary dramatically within measured volume, the total inaccuracies in (choline+creatine)/citrate (CC/C) ratios using Cramér-Rao lower bounds were calculated to compare the accuracy of this method between different prostate regions and measurement resolutions. Our analysis suggests that voxels from prostate base and from periphery of the prostate suffer the most from inaccurate CC/C ratios. To prevent from misleading findings or time consuming manual inspection of spectral quality in each prostate voxel, the metabolic-quality maps, that combine the information of CC/C ratio and its accuracy in one image using the various voxel transparencies, are demonstrated.

MRI-Guided Transurethral Ultrasound Therapy with Real-Time Feedback – a Human Study
Masoom Haider^1,2, Laurence Klotz^3,4, Michael Bronskill^5,6, Kashif Siddiqui³, Alexandra Colquhoun³, Linda Sugar⁷, Rajiv Chopra^5,6
1Medical Imaging, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada; ²Medical Imaging, University of Toronto, Toronto, Ontario, Canada; ³Urology, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada; ⁴Surgery, University of Toronto, Toronto, Ontario, Canada; ⁵Imaging Research, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada; ⁶Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; ⁷Pathology, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada

MRI-guided transurethral ultrasound therapy with real-time thermometry feedback has the potential to reduce morbidity of prostate cancer therapy. To our knowledge this is the first report of the use of this technology in humans. The procedure was performed immediately prior to prostatectomy. Ultrasound energy was delivered while MR thermography was performed. The rate of rotation and output power of the applicator were adjusted by computer control. Treatment times were 9-10 minutes. The maximum temperature distribution map 55°C boundary matched the histologic section showing necrosis. It is feasible to perform accurate spatial heating of the prostate in humans using MRI-guided transurethral ultrasound.

Wash-Out Gradient Derived from Dynamic Contrast-Enhanced MRI Detects Cancerous Tissues and Predicts Gleason Scores in Prostate Cancer
Yu-Jen Chen¹, Woei-Chyn Chu¹, W-Y Isaac Tseng^2,3
1Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan; ²Departments of Medical Imaging National Taiwan University Hospital, Taipei, Taiwan; ³Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan

DCE MRI was reported to assess microvascularity of prostate cancer, and is potentially useful to predict clinical staging. However, there are few studies demonstrating weak association between DCE MRI parameters and Gleason score. In this study, we have retrospectively analyzed the DCE MRI parameters in pathologically confirmed PCA regions. We found that washout gradient values were capable of differentiating PCA from normal tissues and best correlated with Gleason score.

Validation of Multiparametric Magnetic Resonance Imaging and Spectroscopy (DWI/MRSI) to Assess Prostate Cancer Aggressiveness
Thiele Kobus¹, Thomas Hambrock¹, Christina Hulsbergen - Van de Kaa², Jelle Barentsz¹, Arend Heerschap¹, Tom Scheenen^1
1Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; ²Pathology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands

To validate the use of diffusion weighed imaging (DWI) and magnetic resonance spectroscopic imaging (MRSI) for tumor aggressiveness assessment, 37 patients with prostate cancer had a magnetic resonance imaging, DWI and MRSI exam on a 3T system with endorectal coil prior to prostatectomy. Individual and combined DWI and MRSI methods were used to discriminate between high- and low-grade tumors using histopathology as gold standard. Combining DWI and MRSI with linear discriminant analysis to separate tumors gave a higher sensitivity and specificity than any of the techniques separately. This suggests that DWI and MRSI provide complementary information about aggressiveness.

Evaluating and Relating Contrast Mechanisms in Prostate Cancer: Heterogeneity Within Normal and Tumor Regions at 3.0 T
Sharon Giles¹, Sophie F. Riches², Veronica A. Morgan¹, Catherine Simpkin¹, Nandita deSouza^2
1Cancer Research UK and EPSRC Cancer Imaging Centre, Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom; ²Cancer Research UK and EPSRC Cancer Imaging Centre, Institute of Cancer Research & Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom

We report T2, magnetisation transfer ratios, and apparent diffusion coefficients for prostate tissues at 3T. ADC showed a lower coefficient of variation for all prostate regions compared to other parameters, indicating it to be more reliable at differentiating tumor from non-tumor in the prostate. Negative correlation of ADC with MTR suggests that diffusion-weighted contrast may be linked to features other than cellularity, with presence of large macromolecules playing a role.

Does Quantification of T2 SNR Decrease After USPIO Administration Allow Differentiation Between Benign and Malignant Normal Sized Pelvic Lymph Nodes?
Johannes M. Froehlich¹, Benedikt Rückriem¹, Maria Triantafyllou¹, Frederic D. Birkhaeuser², Michael von Gunten³, Peter Vermathen⁴, Harriet C. Thoeny^1
1Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital, Bern, Switzerland; ²Department of Urology, University Hospital, Bern, Switzerland; ³Institute of Pathology, University Hospital, Bern, Switzerland; ⁴Department of Clinical Research, University Hospital, Bern, Switzerland

Methodologically the staging of lymph nodes based on uptake of USPIO is judged on a qualitative level analyzing signal decrease and distribution on T2/T2*-weighted sequences. Quantification of SI/SNR-decrease in 320 lymph nodes comprising 20 malignant lymph nodes, 57 benign inguinal and 243 benign iliacal lymph nodes revealed significant differences (p<0.05) when comparing benign with malignant lymph nodes. Contrary to iliacal lymph nodes (24.8% ± 54.6%) inguinal ones presented limited SNR decrease (3.4% ± 55.4%). Substantial overlap of single data, limit the diagnostic potential of quantification. In practice morphological criteria, fatty content and localization of lymph nodes must be considered.

Tissue Segmentation Improves Prostate Cancer Detection with Artificial Neural Networks Analysis of ¹H MRSI
Lukasz Matulewicz¹, Jacobus F. Jansen², Herbert A. Vargas Alvarez², Oguz Akin², Samson Fine², Amita Shukla-Dave², James Eastham², Hedvig Hricak², Jason A. Koutcher², Kristen L. Zakian^2
1Memorial Sloan-Kettering Cancer Center, New York, NY, United States; ²Memorial Sloan-Kettering Cancer Center, New York, NY, United States

Artificial Neural Network (ANN) model was introduced for automatic detection of tumor voxels in the prostate from 1H-MRSI datasets with additional information about tissue segmentation. The ANN’s accuracy for automatic detection of tumor voxels in the prostate MRSI datasets was demonstrated. Applying tissue segmentation from MRI as an additional input to ANN improves the accuracy of detecting tumor voxels from MRSI.

Absolute Quantification in 1H MRSI of the Prostate at 3T
Paul Michael Walker^1,2, Gilles Créhange³, Sébastien Parfait², Alexandre Cochet¹, Philippe Maingon³, Luc Cormier¹, François Brunotte^1,2
1University Hospital of Dijon, Dijon, France; ²LE2I, University of Burgundy, Dijon, France; ³Radiotherapy Department, CGFL, Dijon, France

Although, it is common in MRSI to use a Choline/Citrate ratio when evaluating PCa, the use of citrate (Cit) as a reference is questionable in the context of treatment such as hormonotherapy and radiotherapy, because Cit levels fall very sharply even in non-cancerous tissue. We have proposed an absolute quantification method at 3T and we observed significantly higher Cit in normal PZ than in CG tissue. However, in PCa, reductions in Cit were not accompanied by important increases in tCho, suggesting increases in tCho/Cit are primarily due to loss of Cit and not to a sharp rise in tCho.