PURPOSE: Prostate cancer remains the second leading cancer killer of men, yet it is also a disease with a high rate of overtreatment. Diffusion-weighted imaging (DWI) has shown promise as a reliable, grade-sensitive imaging method, but it is limited by low image quality. Currently, DWI quality image is directly related to low gradient amplitudes, since weak gradients must be compensated with long echo times. METHODS: We propose a new type of MRI accessory, an "inside-out" and nonlinear gradient, whose sole purpose is to deliver diffusion encoding to a region of interest. Performance was simulated in OPERA and the resulting fields were used to simulate DWI with two-compartment and kurtosis models. Experiments with a nonlinear head gradient prove the accuracy of DWI and apparent diffusion coefficient (ADC) maps encoded with nonlinear gradients. RESULTS: Simulations validated thermal and mechanical safety while showing a 5- to 10-fold increase in gradient strength over prostate. With these strengths, lesion contrast to noise ratio in ADC maps approximately doubled for a range of anatomical positions. Proof-of-principle experiments show that spatially varying b-values can be corrected for accurate DWI and ADC. CONCLUSIONS: Dedicated nonlinear diffusion encoding hardware could improve prostate DWI.
PURPOSE: Prostate cancer remains the second leading cancer killer of men, yet it is also a disease with a high rate of overtreatment. Diffusion-weighted imaging (DWI) has shown promise as a reliable, grade-sensitive imaging method, but it is limited by low image quality. Currently, DWI quality image is directly related to low gradient amplitudes, since weak gradients must be compensated with long echo times. METHODS: We propose a new type of MRI accessory, an "inside-out" and nonlinear gradient, whose sole purpose is to deliver diffusion encoding to a region of interest. Performance was simulated in OPERA and the resulting fields were used to simulate DWI with two-compartment and kurtosis models. Experiments with a nonlinear head gradient prove the accuracy of DWI and apparent diffusion coefficient (ADC) maps encoded with nonlinear gradients. RESULTS: Simulations validated thermal and mechanical safety while showing a 5- to 10-fold increase in gradient strength over prostate. With these strengths, lesion contrast to noise ratio in ADC maps approximately doubled for a range of anatomical positions. Proof-of-principle experiments show that spatially varying b-values can be corrected for accurate DWI and ADC. CONCLUSIONS: Dedicated nonlinear diffusion encoding hardware could improve prostate DWI.
Authors: M Minhaj Siddiqui; Soroush Rais-Bahrami; Baris Turkbey; Arvin K George; Jason Rothwax; Nabeel Shakir; Chinonyerem Okoro; Dima Raskolnikov; Howard L Parnes; W Marston Linehan; Maria J Merino; Richard M Simon; Peter L Choyke; Bradford J Wood; Peter A Pinto Journal: JAMA Date: 2015-01-27 Impact factor: 56.272
Authors: Jeffrey C Weinreb; Jelle O Barentsz; Peter L Choyke; Francois Cornud; Masoom A Haider; Katarzyna J Macura; Daniel Margolis; Mitchell D Schnall; Faina Shtern; Clare M Tempany; Harriet C Thoeny; Sadna Verma Journal: Eur Urol Date: 2015-10-01 Impact factor: 20.096
Authors: Courtney A Woodfield; Glenn A Tung; David J Grand; John A Pezzullo; Jason T Machan; Joseph F Renzulli Journal: AJR Am J Roentgenol Date: 2010-04 Impact factor: 3.959
Authors: Jason P Stockmann; Gigi Galiana; Leo Tam; Christoph Juchem; Terence W Nixon; R Todd Constable Journal: Magn Reson Med Date: 2012-05-14 Impact factor: 4.668
Authors: Michael A Liss; Nathan S White; J Kellogg Parsons; Natalie M Schenker-Ahmed; Rebecca Rakow-Penner; Joshua M Kuperman; Hauke Bartsch; Hyung W Choi; Robert F Mattrey; William G Bradley; Ahmed Shabaik; Jiaoti Huang; Daniel J A Margolis; Steven S Raman; Leonard S Marks; Christopher J Kane; Robert E Reiter; Anders M Dale; David S Karow Journal: Front Oncol Date: 2015-02-17 Impact factor: 6.244