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MP7-17 DIFFERENTIAL DETECTION OF LESIONS ON MULTI-PARAMETRIC PROSTATE MRI WITH OR WITHOUT USE OF AN ENDORECTAL COIL BASED ON QUANTITATIVE MEASURES OF OBESITY
THE JOURNAL OF UROLOGYâ
Vol. 191, No. 4S, Supplement, Saturday, May 17, 2014
MP7-17 DIFFERENTIAL DETECTION OF LESIONS ON MULTIPARAMETRIC PROSTATE MRI WITH OR WITHOUT USE OF AN ENDORECTAL COIL BASED ON QUANTITATIVE MEASURES OF OBESITY Soroush Rais-Bahrami*, Murat Elsekkaki, Baris Turkbey, Hong Truong, Harsh Agarwal, Arvin George, M. Minhaj Siddiqui, Marcelino Bernardo, Kinzya Grant, Annerleim Walton-Diaz, Jason Rothwax, Dima Raskolnikov, Nabeel Shakir, Chinonyerem Okoro, Lambros Stamatakis, Maria Merino, Bradford Wood, Peter Choyke, Peter Pinto, Bethesda, MD INTRODUCTION AND OBJECTIVES: Multiparametric 3T MRI (MP-MRI) with the use of an endorectal coil (ERC) provides improved signal to noise ratio for evaluation of prostatic lesions suspicious for prostate cancer. Herein, we aim to determine the degree of lesion identification lost by eliminating the use of an ERC based upon measures of obesity. METHODS: Prospectively collected data on 20 patients on an active surveillance protocol at the National Cancer Institute who have undergone non-ERC MP-MRI in 2013 following a prior ERC MP-MRI were analyzed. MP-MRI prostatic lesions suspicious for prostate cancer were identified and recorded on both ERC and non-ERC studies for each patient. Patient demographics including age, PSA, BMI, abdominal girth, waist circumference, and the drop distance from the anterior abdominal wall to the anterior aspect of the prostate were recorded. Quantitative measures of obesity were measured on T2-weighted MRI sequences. These parameters were analyzed using univariate and multivariable linear regression models individually with age and PSA to assess for significance in the decrease in number of lesions identified on followup studies without ERC use. RESULTS: The average number of lesions identified on ERC MP-MRI and followup non-ERC MP-MRI was 1.40.9 and 0.50.7, respectively. On univariate analysis, age and PSA were not significantly associated with a decrease in the number of lesions identified when the ERC was not used on followup MP-MRI. Of the quantitative parameters of obesity, on univariate analysis, greater BMI (p¼0.01) and abdominal girth (p¼0.0097) were significantly associated with a larger differential in the number of lesions identified. On multivariable linear regression models incorporating each of the measures of obesity with age and PSA, BMI (p¼0.026) and abdominal girth (p¼0.019) remained significant independent predictors of the difference in numbers of lesions identified between ERC and non-ERC studies. CONCLUSIONS: Typically more intraprostatic lesions are identified by MP-MRI performed with ERC due to the optimized signal to noise ratio. This difference is more dramatic in obese patients where the distance between body and surface coils and the prostate gland are increased. BMI and abdominal girth are predictors of significantly lower lesion identification when ERC is eliminated from the MP-MRI study. Since obesity has a negative impact on the detection of prostate cancer with non-ERC MRI, ERC use may be most important in this patient population. Source of Funding: none
MP7-18 VISUALIZATION OF PERIPROSTATIC NERVE FIBERS BEFORE AND AFTER RADICAL PROSTATECTOMY USING DIFFUSION TENSOR MAGNETIC RESONANCE IMAGING WITH TRACTOGRAPHY Hideaki Miyake*, Kazuhiro Kitajima, Satoru Takahashi, Yoshiko Ueno, Kazuro Sugimura, Masato Fujisawa, Kobe, Japan INTRODUCTION AND OBJECTIVES: Diffusion tensor imaging (DTI) and tractography have emerged as non-invasive MRI techniques providing in vivo information on neural pathway in the brain. Recently, this technology has also been adopted for mapping of periprostatic nerve fibers; however, there have not been any studies assessing the
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changes in nerve fibers by using this imaging modality before and after radical prostatectomy (RP) according to the type of surgical management of neurovascular bundle (NVB). The objective of this study was to evaluate whether the DTI technique with tractography can visualize changes in the numbers of periprostatic nerve fibers at different regions of the prostate on each side following nerve-sparing and non-nervesparing RPs. METHODS: Fifty-two patients with clinically localized prostate cancer underwent 3-Tesla MRI including DTI before and after RP. The periprostatic nerves were analyzed by separately tracking the fibers to the left and right of the posterolateral sectors at the base, mid-gland and apex. The numbers of tracts were then calculated, and changes in the numbers of these nerve tracts on each side before and after nervesparing and non-nerve-sparing RPs were compared. In this series, preservation of NVB was generally carried out by the interfascial dissection. RESULTS: Five patients were excluded from the analysis due to poor image quality, and 8 prostatic sectors, in which partial nervesparing surgery for resecting nerve fibers around the base area alone was undertaken, were also excluded; therefore, a total of 86 prostatic sectors were analyzed in this series. In 69 prostatic sectors subjected to non-nerve-sparing procedure, the numbers of tracts were significantly decreased at the base (218.8198.8 vs. 60.588.7, p<0.0001), midgland (124.1134.5 vs. 32.545.7, p<0.0001) and apex (103.1127.4 vs. 29.157.1, p<0.0001). In 17 prostatic sectors subjected to nervesparing procedure, the numbers of tracts were not changed significantly at the base (170.5139.7 vs. 127.7146.0, p¼0.078), mid-gland (134.3140.8 vs. 83.758.3, p¼0.067) and apex (64.168.4 vs. 62.361.9, p¼0.46). CONCLUSIONS: Although further assessment would be required, the DTI technique with tractography may be feasible for visualization of periprostatic nerve fibers; thefore, this imaging technique could be a useful modality to help guide accurate surgical procedure for managing NVB during both nerve-sparing and nonnerve-sparing RPs. Source of Funding: None
MP7-19 IN VIVO MAGNETIC RESONANCE ELASTOGRAPHY TO IMAGE PROSTATE ANATOMY IN PATIENTS WITH PROSTATE CANCER: A FEASIBILITY STUDY Daniel Yelfimov*, Phillip Rossman, Kevin Glaser, Matthew Tollefson, Akira Kawashima, David Woodrum, Richard Ehman, Lance Mynderse, Rochester, MN INTRODUCTION AND OBJECTIVES: Elasticity as a biomarker for prostate cancer is a promising field of research. Magnetic resonance elastography (MRE) applies a phase-contrast imaging sequence to detect the propagation of shear waves generated by a mechanical driver system in tissues to measure elasticity differences. Mechanical drivers applied externally to the skin have failed due to attenuation of shear waves by soft tissues and bones. Transurethral studies have been limited to ex vivo or non-human models. Our objective was to demonstrate the feasibility of prostate MRE using a transurethral actuator in human volunteers with a diagnosis of prostate cancer. METHODS: This was a HIPPA-compliant, IRB-approved prospective study. Five patients with known prostate cancer were recruited. After acquisition of standard clinical multiparametric (mp) MRI using a 3Tesla magnet and an endorectal coil, a transurethral catheter attached to an external pneumatic driver system translated longitudinal motion to the prostate at frequencies ranging from 150-233 Hz. Phase-contrast imaging sequences were utilized to detect the propagation of the resulting shear waves. Quantitative elastograms were generated by post-acquisition processing and compared to standard mpMRI. All patients proceeded with radical prostatectomy following the study. mpMRI and MRE images correlated with histopathology.
Vol. 191, No. 4S, Supplement, Saturday, May 17, 2014
MP7-17 DIFFERENTIAL DETECTION OF LESIONS ON MULTIPARAMETRIC PROSTATE MRI WITH OR WITHOUT USE OF AN ENDORECTAL COIL BASED ON QUANTITATIVE MEASURES OF OBESITY Soroush Rais-Bahrami*, Murat Elsekkaki, Baris Turkbey, Hong Truong, Harsh Agarwal, Arvin George, M. Minhaj Siddiqui, Marcelino Bernardo, Kinzya Grant, Annerleim Walton-Diaz, Jason Rothwax, Dima Raskolnikov, Nabeel Shakir, Chinonyerem Okoro, Lambros Stamatakis, Maria Merino, Bradford Wood, Peter Choyke, Peter Pinto, Bethesda, MD INTRODUCTION AND OBJECTIVES: Multiparametric 3T MRI (MP-MRI) with the use of an endorectal coil (ERC) provides improved signal to noise ratio for evaluation of prostatic lesions suspicious for prostate cancer. Herein, we aim to determine the degree of lesion identification lost by eliminating the use of an ERC based upon measures of obesity. METHODS: Prospectively collected data on 20 patients on an active surveillance protocol at the National Cancer Institute who have undergone non-ERC MP-MRI in 2013 following a prior ERC MP-MRI were analyzed. MP-MRI prostatic lesions suspicious for prostate cancer were identified and recorded on both ERC and non-ERC studies for each patient. Patient demographics including age, PSA, BMI, abdominal girth, waist circumference, and the drop distance from the anterior abdominal wall to the anterior aspect of the prostate were recorded. Quantitative measures of obesity were measured on T2-weighted MRI sequences. These parameters were analyzed using univariate and multivariable linear regression models individually with age and PSA to assess for significance in the decrease in number of lesions identified on followup studies without ERC use. RESULTS: The average number of lesions identified on ERC MP-MRI and followup non-ERC MP-MRI was 1.40.9 and 0.50.7, respectively. On univariate analysis, age and PSA were not significantly associated with a decrease in the number of lesions identified when the ERC was not used on followup MP-MRI. Of the quantitative parameters of obesity, on univariate analysis, greater BMI (p¼0.01) and abdominal girth (p¼0.0097) were significantly associated with a larger differential in the number of lesions identified. On multivariable linear regression models incorporating each of the measures of obesity with age and PSA, BMI (p¼0.026) and abdominal girth (p¼0.019) remained significant independent predictors of the difference in numbers of lesions identified between ERC and non-ERC studies. CONCLUSIONS: Typically more intraprostatic lesions are identified by MP-MRI performed with ERC due to the optimized signal to noise ratio. This difference is more dramatic in obese patients where the distance between body and surface coils and the prostate gland are increased. BMI and abdominal girth are predictors of significantly lower lesion identification when ERC is eliminated from the MP-MRI study. Since obesity has a negative impact on the detection of prostate cancer with non-ERC MRI, ERC use may be most important in this patient population. Source of Funding: none
MP7-18 VISUALIZATION OF PERIPROSTATIC NERVE FIBERS BEFORE AND AFTER RADICAL PROSTATECTOMY USING DIFFUSION TENSOR MAGNETIC RESONANCE IMAGING WITH TRACTOGRAPHY Hideaki Miyake*, Kazuhiro Kitajima, Satoru Takahashi, Yoshiko Ueno, Kazuro Sugimura, Masato Fujisawa, Kobe, Japan INTRODUCTION AND OBJECTIVES: Diffusion tensor imaging (DTI) and tractography have emerged as non-invasive MRI techniques providing in vivo information on neural pathway in the brain. Recently, this technology has also been adopted for mapping of periprostatic nerve fibers; however, there have not been any studies assessing the
e73
changes in nerve fibers by using this imaging modality before and after radical prostatectomy (RP) according to the type of surgical management of neurovascular bundle (NVB). The objective of this study was to evaluate whether the DTI technique with tractography can visualize changes in the numbers of periprostatic nerve fibers at different regions of the prostate on each side following nerve-sparing and non-nervesparing RPs. METHODS: Fifty-two patients with clinically localized prostate cancer underwent 3-Tesla MRI including DTI before and after RP. The periprostatic nerves were analyzed by separately tracking the fibers to the left and right of the posterolateral sectors at the base, mid-gland and apex. The numbers of tracts were then calculated, and changes in the numbers of these nerve tracts on each side before and after nervesparing and non-nerve-sparing RPs were compared. In this series, preservation of NVB was generally carried out by the interfascial dissection. RESULTS: Five patients were excluded from the analysis due to poor image quality, and 8 prostatic sectors, in which partial nervesparing surgery for resecting nerve fibers around the base area alone was undertaken, were also excluded; therefore, a total of 86 prostatic sectors were analyzed in this series. In 69 prostatic sectors subjected to non-nerve-sparing procedure, the numbers of tracts were significantly decreased at the base (218.8198.8 vs. 60.588.7, p<0.0001), midgland (124.1134.5 vs. 32.545.7, p<0.0001) and apex (103.1127.4 vs. 29.157.1, p<0.0001). In 17 prostatic sectors subjected to nervesparing procedure, the numbers of tracts were not changed significantly at the base (170.5139.7 vs. 127.7146.0, p¼0.078), mid-gland (134.3140.8 vs. 83.758.3, p¼0.067) and apex (64.168.4 vs. 62.361.9, p¼0.46). CONCLUSIONS: Although further assessment would be required, the DTI technique with tractography may be feasible for visualization of periprostatic nerve fibers; thefore, this imaging technique could be a useful modality to help guide accurate surgical procedure for managing NVB during both nerve-sparing and nonnerve-sparing RPs. Source of Funding: None
MP7-19 IN VIVO MAGNETIC RESONANCE ELASTOGRAPHY TO IMAGE PROSTATE ANATOMY IN PATIENTS WITH PROSTATE CANCER: A FEASIBILITY STUDY Daniel Yelfimov*, Phillip Rossman, Kevin Glaser, Matthew Tollefson, Akira Kawashima, David Woodrum, Richard Ehman, Lance Mynderse, Rochester, MN INTRODUCTION AND OBJECTIVES: Elasticity as a biomarker for prostate cancer is a promising field of research. Magnetic resonance elastography (MRE) applies a phase-contrast imaging sequence to detect the propagation of shear waves generated by a mechanical driver system in tissues to measure elasticity differences. Mechanical drivers applied externally to the skin have failed due to attenuation of shear waves by soft tissues and bones. Transurethral studies have been limited to ex vivo or non-human models. Our objective was to demonstrate the feasibility of prostate MRE using a transurethral actuator in human volunteers with a diagnosis of prostate cancer. METHODS: This was a HIPPA-compliant, IRB-approved prospective study. Five patients with known prostate cancer were recruited. After acquisition of standard clinical multiparametric (mp) MRI using a 3Tesla magnet and an endorectal coil, a transurethral catheter attached to an external pneumatic driver system translated longitudinal motion to the prostate at frequencies ranging from 150-233 Hz. Phase-contrast imaging sequences were utilized to detect the propagation of the resulting shear waves. Quantitative elastograms were generated by post-acquisition processing and compared to standard mpMRI. All patients proceeded with radical prostatectomy following the study. mpMRI and MRE images correlated with histopathology.