Jay M. Pittman^1,2, Aritrick Chatterjee^1,2, Teodora Szasz³, Grace Lee^1,2, Mihai Giurcanu⁴, Milica Medved^1,2, Ambereen Yousuf^1,2, Ajit Devaraj⁵, Aytekin Oto^1,2, and Gregory S. Karczmar^1,2
1Radiology, The University of Chicago, Chicago, IL, United States, ²Sanford J. Grossman Center of Excellence in Prostate Imaging and Image Guided Therapy, The University of Chicago, Chicago, IL, United States, ³Research Computing Center, The University of Chicago, Chicago, IL, United States, ⁴Department of Public Health Sciences, The University of Chicago, Chicago, IL, United States, ⁵Philips Research North America, Cambridge, MA, United States

Diffusion Weighted Imaging (DWI) MRI detects prostate cancers but is very sensitive to motion artifacts. There has been little quantitative evaluation of variability to guide clinical use of DWI. We found very high variability between individual acquisitions used for averaging at high b-values (% ranges of 74.08% - 115.56% in cancers and 53.53% - 159.91% in normal prostate tissue), primarily due to motion during diffusion-sensitizing gradients. High signals in cancer voxels appear in some acquisitions but not others. Therefore, standard averaging can obscure cancers. We propose alternative methods for combining information from individual images at each b-value to maximize diagnostic accuracy.

Kaibao Sun¹, Guangyu Dan^1,2, Zheng Zhong^1,2, and Xiaohong Joe Zhou^1,2,3
1Center for MR Research, University of Illinois at Chicago, Chicago, IL, United States, ²Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, ³Departments of Radiology and Neurosurgery, University of Illinois at Chicago, Chicago, IL, United States

The dependence of apparent diffusion coefficient (ADC) on echo time (TE) has been observed in a number of biological tissues. Such coupling can be exploited to extract tissue microstructural information. We herein introduce a time-efficient sequence that is capable of studying the interplay between ADC and TE. The sequence incorporated multiple echo-train readouts into diffusion-weighted echo planar imaging, together with a 2D RF excitation pulse to reduce the FOV, thereby allowing multiple effective TEs in an acquisition. With this sequence, ADCs were evaluated at three TEs and T₂*s at three b-values. The proposed technique has been demonstrated in the prostate.

Yu Ueda¹, Tsutomu Tamada², Makoto Obara¹, Tetsuo Ogino¹, Daisuke Morimoto-Ishikawa³, Hiroyasu Sanai², Koji Yoshida², Ayumu Kido², Tomoko Hyodo⁴, Kazunari Ishii⁴, Masami Yoneyama¹, and Marc Van Cauteren^5
1Philips Japan, Tokyo, Japan, ²Department of Radiology, Kawasaki Medical School, Okayama, Japan, ³Radiology Center, Kindai University Hospital, Osaka, Japan, ⁴Department of Radiology, Kindai University, Osaka, Japan, ⁵BIU MR Asia Pacific, Philips Healthcare, Tokyo, Japan

The usefulness of short TR DWI in prostate has been reported. However, care should be taken when setting TR as DWI with shorter TR suffers from low SNR. It would be beneficial to generate an additional DWI with shorter TR (e.g. 1000ms) from DWIs with two different TR (e.g. conventional [long] and short TR such as 6000 and 2000ms). The synthetic DWI at b = 1000 s/mm² (DWI₁₀₀₀) with shorter TR of 1000ms calculated from DWIs with TR of 6000 and 2000ms had a tendency to show better diffusion contrast compared to the real-acquired DWI₁₀₀₀ with long TR of 6000ms.

David Atkinson¹, Fiona Gong¹, Giorgio Brembilla¹, and Shonit Punwani^1
1Centre for Medical Imaging, University College London, London, United Kingdom

Quantification of luminal water components provides tissue information in prostate MRI. The luminal water fraction (LWF) summarizes the amount of ‘luminal’, or longer T2 material in a distribution of tissue T2s. The parameters of this T2 distribution are found by fitting to the MR signal acquired from a multiple echo sequence. Iterative fitting of T2 distributions can be slow and different T2 distributions can give similar fits to data. The division into long and short T2 tissue for LWF calculations suggests that a simpler model may be effective. Two rapid alternative fits are presented.

Ayumu Kido¹, Tsutomu Tamada¹, Yu Ueda², Masami Yoneyama², and Akira Yamamoto^1
1Radiology, Kawasaki Medical School, Okayama, Japan, ²Philips Japan, Tokyo, Japan

High b value DWI (b2000) shows insufficient image contrast between benign and malignant tissues and much overlap between ADCs of low grade and those of high-grade prostate cancers (PCs). Forty-nine patients with PC underwent multiparametric MRI including ultra-high b value DWI (b3000) and high b value DWI. Signal intensity of normal prostate was significantly lower in b3000 than in b2000. Other image quality parameters, tumor detection ability, and discrimination ability of PC aggressiveness between b3000 and b2000 were comparable. Compared with high b value DWI, ultra-high b value DWI could not contribute to increased diagnostic performance in PC.

Allison Y Zhong¹, Leonardino A Digma¹, Troy Hussain¹, Christine H Feng¹, Christopher C Conlin², Karen Tye¹, Asona J Lui¹, Maren MS Andreassen³, Ana E Rodríguez-Soto², Roshan Karunamuni¹, Joshua Kuperman², Rebecca Rakow-Penner², Michael E Hahn², Anders M Dale^2,4, and Tyler M Seibert^1,2,5
1Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, United States, ²Department of Radiology, University of California San Diego, La Jolla, CA, United States, ³Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway, ⁴Department of Neurosciences, University of California San Diego, La Jolla, CA, United States, ⁵Department of Bioengineering, University of California San Diego, La Jolla, CA, United States

Multiparametric MRI (mpMRI) improves prostate cancer diagnosis, but conventional apparent diffusion coefficient (ADC) and PI-RADS have poor reliability. We evaluated restriction spectrum imaging MRI (RSI-MRI) as a quantitative, patient-level classifier of higher-grade prostate cancer (grade group ≥2) and compared performance to conventional ADC and PI-RADS. Area under the receiver operating characteristic curve values for ADC, RSI-C₁, and PI-RADS were 0.58 [0.51,0.67], 0.76 [0.68,0.83], and 0.78 [0.71,0.85], respectively. RSI-C₁ was superior to ADC (p=0.003) as a patient-level classifier of higher-grade prostate cancer. Performance of RSI-C₁ was comparable to that of PI-RADS (p=0.59).

Ayumu kido¹, Tsutomu Tamada¹, Yu Ueda², Masami Yoneyama², Jaladhar Neelavalli³, and Akira Yamamoto^1
1Kawasaki Medical School, Okayama, Japan, ²Philips Japan, Tokyo, Japan, ³Philips India, Bangalore, India

Single-shot EPI (sshEPI) DWI still suffers from distortion and blurring. Multi-shot EPI (mshEPI) DWI called IRIS and sshEPI DWI using C-SENSE (a combination of parallel imaging and compressed sensing) enables to reduce distortion and blurring. A total of 14 prostate cancer (PC) patients underwent mpMRI including sshEPI DWI, IRIS, and sshEPI DWI using C-SENSE under the same scan time. The sshEPI DWI has comparable the diagnostic performance of PC equivalent to sshEPI DWI using C-SENSE and IRIS, whereas sshEPI DWI using C-SENSE and IRIS improve the image distortion and image blurring compared to sshEPI DWI.

Ayumu Kido¹, Tsutomu Tamada¹, Yu Ueda², Masami Yoneyama², and Akira Yamamoto^1
1Radiology, Kawasaki Medical School, Okayama, Japan, ²Phillips Japan, Tokyo, Japan

Image quality of DWI with single-shot echo-planar imaging (ssEPI) suffers from low SNR in high b-value acquisition. Compressed SENSE (C-SENSE) allow for a reduction of the noise. A total of 26 patients with prostate cancer (PC) underwent mpMRI including DWI with ssEPI and SENSE (EPIS) and DWI with ssEPI and C-SENSE (EPICS). SNR was significantly higher in EPICS than in EPIS. In comparison between ADC of clinically significant PC and ADC of clinically insignificant PC, only EPICS had significant difference. Compared with EPIS, EPICS improves the image quality and may contribute to increased diagnostic performance of tumor aggressiveness in PC.

Archana Vadiraj Malagi¹, Virender Kumar², Kedar Khare³, Chandan J. Das⁴, and Amit Mehndiratta^1,5
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, ²Department of Nuclear Magnetic Resonance (NMR),, All India Institute of Medical Sciences Delhi, New Delhi, India, ³Department of Physics, Indian Institute of Technology Delhi, New Delhi, India, ⁴Department of Radiodiagnosis, All India Institute of Medical Sciences Delhi, New Delhi, India, ⁵Department of Biomedical Engineering, All India Institute of Medical Sciences Delhi, New Delhi, India

IVIM-DKI was used to evaluate clinical utility and diagnostic performance of IVIM-DKI parameters in characterization of prostate cancer(PCa) against benign prostatic hyperplasia(BPH) and healthy tissues. Sixteen patients suffering from PCa and BPH were recruited and underwent IVIM-DKI with routine MR sequences and biopsy. IVIM-DKI signal was modelled using hybrid model with total variation (TV) penalty function which removes any spurious values in parameters adaptively. HY with TV method produced high diagnostic performance (AUC:D=0.94-0.98, f=0.82-0.85 and k=0.85-0.91) than HY method for all tissues and high-quality parameter maps. IVIM-DKI parameters (D,f,k) showed significant differences between tumor and BPH and healthy tissue.

Chun-Ying Shen¹, Chia-Wei Li², Chien-Yuan Lin², and Ching-Hua Yang^1
1Department of Radiology, Taovuan General Hospital, Ministry of Health and Welfare, Taovuan, Taiwan, ²GE Healthcare, Taipei, Taiwan

This study aimed to evaluate and compare quantitatively the effect of image distortion of multiplexed sensitivity encoding (MUSE) and conventional single-shot echo-planar imaging (ssEPI) for diffusion-weighted imaging (DWI) of the prostate. Our result showed that prostate images by MUSE-DWI can provide significant less distortions and higher SNR than that by conventional ssEPI-DWI at the similar acquisition time.

Hiroaki Takahashi¹, Kotaro Yoshida², Akira Kawashima³, Num Ju Lee⁴, Adam T Froemming⁴, Daniel A Adamo⁴, Ashish Khandelwal⁴, Candice W Bolan⁵, Matthew T Heller⁶, Robert P Hartman⁴, Bohyun Kim⁴, Kenneth A Philbrick⁴, Rickey E Carter⁵, Lance A Mynderse⁴, Mitchell R Humphreys⁶, and Naoki Takahashi^4
1Department of Radiology, Mayo Clinic, Rochester, Rochester, MN, United States, ²Department of Diagnostic Radiology, Kanazawa University School of Medical Science, Kanazawa, Japan, ³Department of Radiology, Mayo Clinic, Arizona, Scottsdale, AZ, United States, ⁴Mayo Clinic, Rochester, Rochester, MN, United States, ⁵Mayo Clinic, Florida, Jacksonville, FL, United States, ⁶Mayo Clinic, Arizona, Scottsdale, AZ, United States

This study evaluated different 2D-ROI methods to measure ADC of prostate lesions on prostate MR. The optimal method for measuring ADC values of suspected lesion for differentiating csPCa and non-csPCa on prostate MRI is 2D-ROI method placed on the lowest ADC area using 6-8 mm2 / 8-9 pixel-size ROI (AUC, peripheral zone lesions: 0.740-0.743 / 0.742-0.743, transition zone lesions: 0.709-0.710 / 0.711-0.713). Use of a standardized ROI size improves interobsever variability.

Milica Medved^1,2, Aritrick Chatterjee^1,2, Ajit Devaraj³, Carla Harmath¹, Grace Lee¹, Ambereen Yousuf^1,2, Tatjana Antic⁴, Aytekin Oto^1,2, and Gregory S Karczmar^1,2
1Radiology, The University of Chicago, Chicago, IL, United States, ²Sanford J. Grossman Center of Excellence in Prostate Imaging and Image Guided Therapy, The University of Chicago, Chicago, IL, United States, ³Philips Research NA, Cambridge, MA, United States, ⁴Pathology, The University of Chicago, Chicago, IL, United States

HiSS MRI is an echo-planar spectroscopic imaging (EPSI)-based method focusing on the shape and structure of the water and fat resonances.  In the prostate, temporal signal decay parameters (ROC AUC 0.74-0.91) and spectral resonance shape parameters (ROC AUC 0.83-0.91) show high diagnostic potential.  Spectral shape parameters do not correlate strongly with temporal decay parameters.  Thus, they carry information complementary to the standard clinical multi-parametric MRI and can likely be utilized to improve its diagnostic performance in prostate cancer.

Xin Li¹, Eric M. Baker¹, Brendan Moloney¹, Ryan P. Kopp², Fergus V. Coakley³, Mark G. Garzotto⁴, and Charles S. Springer^1
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, United States, ²Urology, Oregon Health & Science University, Portland, OR, United States, ³Radiology, Oregon Health & Science University, Portland, OR, United States, ⁴Urology, Portland VA Center, Portland, OR, United States

The first aMRI [activity MRI] parametric maps of malignant prostate are presented.  They show the differences in cell density [r (cells/μL)], average cell volume [V (pL)], and on-going metabolic activity across the prostate.  Metabolic activity is represented by the mean steady-state cellular water efflux rate constant [k_io (s^-1)], which reflects homeostatic cytolemmal Na⁺,K⁺-ATPase [NKA] enzymatic turnover [fmol(ATP)consumed/s/cell].  In a known Gleason (3 + 4) tumor, r is increased, while V and k_io are decreased – relative to normal-appearing tissue.  Such changes are sensible, and these new biomarkers may be diagnostic and/or predictive. 
 

Yunsong Liu¹, Hongkai Wang², Mingrui Zhuang², Lihua Chen¹, Qingwei Song¹, Shuang Meng¹, and Ailian Liu^1
1The First Affiliated Hospital of Dalian Medical University, Dalian, China, ²Dalian University of Technology, Dalian, China

It remains a challenge to diagnose differentiate PCa from BPH due to their similar clinical symptoms. The aim of this study was to evaluate the value of intratumoral susceptibility signal intensities (ITSS) in differentiating PCa and BPH based on enhanced T2 star-weighted angiography (ESWAN). The diagnostic efficiency was promising well in quantitatively and automatically differentiation of PCa from BPH by ITSS based on ESWAN.

Teodora Szasz¹, Milica Medved², Aritrick Chatterjee², Ajit Devaraj³, Ambereen Yousuf², Xiaobing Fan², Gregory Karczmar², Aytekin Oto², and Grace Lee^2
1Research Computing Center, The University of Chicago, Chicago, IL, United States, ²Department of Radiology, The University of Chicago, Chicago, IL, United States, ³Philips Research North America, Chicago, IL, United States

Diffusion weighted imaging (DWI) is important for prostate cancer diagnosis but is highly sensitive to artifacts. We developed a method for automatically and quantitatively measuring physically implausible DWI signals (PIDS) that could contribute to diagnostic errors. The level of PIDS is significant and similar in all prostate zones, for scans both with and without an endorectal coil, and is strongly correlated with motion.  For scans without the endorectal coil, PIDS is correlated with noise level. In regions with a high percentage of PIDS, PIRADS II criteria may not be optimal, and algorithms that emphasize T2 and DCE-MRI may be preferable.

Angeliki Stamatelatou¹, Diana Sima², Sabine Van Huffel³, Sjaak Van Asten⁴, Arend Heerschap⁴, and Tom Scheenen^4
1Radiology, Radboud UMC, Nijmegen, Netherlands, ²Icometrix, Leuven, Belgium, ³KU Leuven, Leuven, Belgium, ⁴Radboud UMC, Nijmegen, Netherlands

Water-unsuppressed MRSI acquisitions could obliviate the need for additional reference data sampling for signal quantification. We evaluated two methods for post-acquisition water signal removal in 1H-MRSI of the prostate. The method using Löwner Blind Source Separation for filtering the water signal outperformed the matrix-based Hankel Lanczos Singular Value Decomposition method. The two techniques were evaluated and compared against conventional water suppressed data acquisitions in 4 volunteers. The results demonstrate that post-acquisition water removal was successfully implemented in water-unsuppressed prostate MRS(I) data, and that the Löwner filter showed the best performance.

Nicolás Moyano Brandi^1,2,3, Daniel Fino^1,2,4, Joaquín Capó^1,2,3, Federico González^1,4,5, Bruno Lima^1,2, Maximiliano Noceti^1,2,6, Pablo Ariza^1,2, and Andrés Dominguez^1,2
1Magnetic Resonance, Fundacion Escuela de Medicina Nuclear, Mendoza, Argentina, ²Magnetic Resonance, Fundación Argentina para el Desarrollo en Salud, Mendoza, Argentina, ³Universidad de Mendoza, Mendoza, Argentina, ⁴Universidad Nacional de Cuyo, Mendoza, Argentina, ⁵Comisión Nacional de Energía Atómica, Mendoza, Argentina, ⁶Hospital Italiano, Mendoza, Argentina

MRE generates quantitative information of shear modulus. Several challenges exist for the assessment of prostate. Difficulties with wave propagation due to the central location of the prostate, have induced the development of different techniques including transurethral and endorectal drivers. The objectives of this work were to study the 3.0 Tesla trans-pelvic MRE performance in PCa at a standard excitation frequency (⍵) of 60 Hz, as well as the reproducibility of µ at different ⍵ values. In  43 patients, the MRE were acquired using five 2D-SE sequences (⍵ values: 40, 50, 60, 70 and 80 Hz) and GRE 2D sequences

Yi Sui¹, Kay Pepin¹, Phillip J. Rossman¹, Kevin Glaser¹, Lance Mynderse², Richard L. Ehman¹, and Ziying Yin^1
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Urology, Mayo Clinic, Rochester, MN, United States

Slip interface imaging is a MR elastography based technique that enables assessing the mechanical connectivity between the tumor and its sourronding tissues. In this study, we have implemented a distortion-free MRE method (DIADEM-MRE) for detecting slip boundary of the prostate capsule. This technique has the great potential to be used to locate the margin of tumor adherent to the prostatic capsule, thus predicting the present of extraprostatice extension of prostate cancer.

Shuang Li¹, Ailian Liu¹, Lihua Chen¹, Yuanfei Li¹, Shuang Meng¹, Jiazheng Wang², Peng Sun², Qingwei Song¹, and Renwang Pu^1
1The First Affiliated Hospital of Dalian Medical University, Dalian, Dalian, China, ²Philips Healthcare, Beijing, China, Beijing, China

Differential diagnosis of benign prostatic hyperplasia (BPH) and prostatic cancer (PCa) now mainly depends on the results of the pathology. Both amide proton transfer-weighted (APTw) and diffusion-weighted imaging (DWI) are promising non-invasive methods to classify BPH and PCa. In this study, we explore the correlation between the APT values and ADC derived from DWI in BPH and PCa. The results indicate the APT values showa moderate negative correlation with ADC, which confirms both methods are effective in the differential diagnosis of BPH and PCa.

Wenjun HU¹, Ailian Liu¹, Lihua Chen¹, Zhiwei Shen², Jiazheng Wang³, Yi Zhang⁴, and Qingwei Song^1
1The First Affiliated Hospital of Dalian Medical University, Dalian, China, ²Philips Healthcare, Beijing, China, ³Philips Healthcare, Bejing, China, ⁴Zhejiang University, Hangzhou, China

Recently, prostate disease prevalence has been shown to increase gradually. Amide proton transfer-weighted (APTw) imaging, a molecular MRI technique at the protein level, has been applied in the diagnosis of prostate disease. This study aims to explore the optimal scan parameters for prostate APTw MR imaging. The preliminary results showed higher SNR of APTw images in central zones was acquired with the optimal scan parameters including the echo train length, the numbers and thickness of slices, FOV, the type of fold-over suppression and shimming, the size of voxel and phase encoding direction.