FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2014920995> ?p ?o ?g. }

• W2014920995 endingPage "491" @default.
• W2014920995 startingPage "479" @default.
• W2014920995 abstract "Purpose: To summarize the functional anatomy relevant to prostate cancer treatment planning.Methods and Materials: Coronal, axial, and sagittal T2 magnetic resonance imaging (MRI) and MRI angiography were fused by mutual information and registered with computed tomography (CT) scan data sets to improve definition of zonal anatomy of the prostate and critical adjacent structures.Results: The three major prostate zones (inner, outer, and anterior fibromuscular) are visible by T2 MRI imaging. The bladder, bladder neck, and internal (preprostatic) sphincter are a continuous muscular structure and clear definition of the preprostatic sphincter is difficult by MRI. Transition zone hypertrophy may efface the bladder neck and internal sphincter. The external “lower” sphincter is clearly visible by T2 MRI with wide variations in length. The critical erectile structures are the internal pudendal artery (defined by MRI angiogram or T2 MRI), corpus cavernosum, and neurovascular bundle. The neurovascular bundle is visible along the posterior lateral surface of the prostate on CT and MRI, but its terminal branches (cavernosal nerves) are not visible and must be defined by their relationship to the urethra within the genitourinary diaphragm. Visualization of the ejaculatory ducts within the prostate is possible on sagittal MRI. The anatomy of the prostate-rectum interface is clarified by MRI, as is the potentially important distinction of rectal muscle and rectal mucosa.Conclusion: Improved understanding of functional anatomy and imaging of the prostate and critical adjacent structures will improve prostate radiation therapy by improvement of dose and toxicity correlation, limitation of dose to critical structures, and potential improvement in post therapy quality of life. Purpose: To summarize the functional anatomy relevant to prostate cancer treatment planning. Methods and Materials: Coronal, axial, and sagittal T2 magnetic resonance imaging (MRI) and MRI angiography were fused by mutual information and registered with computed tomography (CT) scan data sets to improve definition of zonal anatomy of the prostate and critical adjacent structures. Results: The three major prostate zones (inner, outer, and anterior fibromuscular) are visible by T2 MRI imaging. The bladder, bladder neck, and internal (preprostatic) sphincter are a continuous muscular structure and clear definition of the preprostatic sphincter is difficult by MRI. Transition zone hypertrophy may efface the bladder neck and internal sphincter. The external “lower” sphincter is clearly visible by T2 MRI with wide variations in length. The critical erectile structures are the internal pudendal artery (defined by MRI angiogram or T2 MRI), corpus cavernosum, and neurovascular bundle. The neurovascular bundle is visible along the posterior lateral surface of the prostate on CT and MRI, but its terminal branches (cavernosal nerves) are not visible and must be defined by their relationship to the urethra within the genitourinary diaphragm. Visualization of the ejaculatory ducts within the prostate is possible on sagittal MRI. The anatomy of the prostate-rectum interface is clarified by MRI, as is the potentially important distinction of rectal muscle and rectal mucosa. Conclusion: Improved understanding of functional anatomy and imaging of the prostate and critical adjacent structures will improve prostate radiation therapy by improvement of dose and toxicity correlation, limitation of dose to critical structures, and potential improvement in post therapy quality of life. IntroductionImprovements in prostate cancer radiation therapy depend on improved imaging and improved understanding of the function of critical adjacent structures. Although the established structures of concern in prostate cancer treatment planning have been limited to the rectum and bladder, T2 magnetic resonance imaging (MRI) allows definition of genitourinary and sexual substructures, as well as improved definition of the rectum-prostate interface. Understanding both structural and functional anatomy and clarifying terminology of adjacent structures will improve the capacity to standardize therapy, correlate dose and toxicity, and limit dose for an improved quality of life. There is a vast amount of literature on the improvement of prostate definition by MRI vs. computed tomography (CT) (1Roach M. Faillace-Akazawa P. Malfatti C. et al.Prostate volumes defined by magnetic resonance imaging and computerized tomographic scans for three-dimensional conformal radiotherapy.Int J Radiat Oncol Biol Phys. 1996; 35: 1011-1018Abstract Full Text PDF PubMed Scopus (268) Google Scholar, 2Milosevic M. Voruganti S. Blend R. et al.Magnetic resonance imaging (MRI) for localization of prostatic apex Comparison to computed tomography (CT) and urethrography.Radiother Oncol. 1998; 47: 277-284Abstract Full Text Full Text PDF PubMed Scopus (115) Google Scholar, 3Rasch C. Barillot I. Remeijer P. et al.Definition of the prostate in CT and MRI A multi-observer study.Int J Radiat Oncol Biol Phys. 1999; 43: 57-66Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar, 4Debois M. Oyen R. Maes F. et al.The contribution of magnetic resonance imaging to the three-dimensional treatment planning of localized prostate cancer.Int J Radiat Oncol Biol Phys. 1999; 45: 857-865Abstract Full Text Full Text PDF PubMed Scopus (186) Google Scholar, 5Dubois D.F. Prestidge B.R. Hotchkiss L.A. et al.Intra-observer and inter-observer variability of MR imaging and CT-derived prostate volumes after transperineal interstitial permanent prostate brachytherapy.Radiology. 1998; 207: 785-789PubMed Google Scholar, 6McLaughlin P.W. Narayana V. Drake D.G. et al.Comparison of MRI pulse sequences in defining prostate volume after permanent implantation.Int J Radiat Oncol Biol Phys. 2002; 54: 703-711Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). However, imaging of normal critical adjacent structures has not been emphasized, with the exception of the penile bulb, corpus cavernosum (7Wallner K.E. Merrick G.S. Benson M.L. et al.Penile bulb imaging.Int J Radiat Oncol Biol Phys. 2002; 53: 928-933Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar), and proximal neurovascular bundle (8Wright J.L. Newhouse J.H. Laguna J.L. et al.Localization of neurovascular bundles on pelvic CT and evaluation of radiation dose to structures putatively involved in erectile dysfunction after prostate brachytherapy.Int J Radiat Oncol Biol Phys. 2004; 59: 426-435Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar). In this article, the terminology, functional anatomy, and imaging of the prostate and related structures relevant to prostate treatment planning are reviewed.Such a review is limited for several reasons. The most basic is continued controversy about the structures themselves. Although one might assume that anatomy is a stable body of literature, questions remain about the nature and even existence of certain structures. Is the internal (preprostatic) sphincter a distinct entity separable from the bladder neck? After transition zone (TZ) hypertrophy, is the bladder neck identifiable? Does the genitourinary diaphragm (GUD) exist (9Kaye K.W. Milne N. Creed K. et al.The “urogenital diaphragm,” external urethral sphincter and radical prostatectomy.Aust N Z J Surg. 1997; 67: 40-44Crossref PubMed Scopus (30) Google Scholar)? How does the neurovascular bundle (NVB) reach and connect to the corpus cavernosum (CC) (10Lepor H. Gregerman M. Crosby R. et al.Precise localization of the autonomic nerves from the pelvic plexus to the corpora cavernosa A detailed anatomic study of the adult male pelvis.J Urol. 1985; 133: 207-212PubMed Google Scholar, 11Paick J.S. Donatucci C.F. Lue T.F. Anatomy of cavernous nerves distal to prostate Microdissection study in adult male cadavers.Urology. 1993; 42: 145-149Abstract Full Text PDF PubMed Scopus (79) Google Scholar, 12Akman Y. Liu W. Li Y.W. et al.Penile anatomy under the pubic arch Reconstructive implications.J Urol. 2001; 166: 225-230Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar)? How have anatomic studies repeated with markers, such as nerve studies employing nitrous oxide stains to clarify the complex physiology of erections (13Burnett A.L. Tillman S.L. Chank T.S.K. et al.Immunohistochemical localization of nitric oxide synthase in the autonomic innervation of the human penis.J Urol. 1993; 150: 73-76PubMed Google Scholar), altered the nomenclature and classification of pelvic nerves? Although basic controversy is acknowledged in the current review, the discussion of such controversy is limited.A second barrier is terminology. The word “central,” for example, is used to define the peri-ejaculatory duct zone visible in the prostate of young men, a zone compressed and not visible as a distinct entity in the adult. It is also used to define the TZ hypertrophy clearly visible on ultrasound and MRI as a distinct central zone. Several rational systems of terminology are available based on different conceptions of the same anatomy. Although this controversy is acknowledged in the current review, no attempt is made to reconcile the differences, and nomenclature is discussed on a structure-by-structure basis rather than a single system of nomenclature.The third barrier is imaging. Not all known structures are visible, even with the most sophisticated imaging. For example, the NVB adjacent to the prostate may be defined on MRI or CT (8Wright J.L. Newhouse J.H. Laguna J.L. et al.Localization of neurovascular bundles on pelvic CT and evaluation of radiation dose to structures putatively involved in erectile dysfunction after prostate brachytherapy.Int J Radiat Oncol Biol Phys. 2004; 59: 426-435Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar), but the terminal branches that course through the GUD are not visible on MRI and must be defined by a fixed relationship to the membranous urethra, which is clearly visible. The emphasis in the current review is the whole pelvic region rather than rectal coil (14Coakley F.V. Hricak H. Wefer A.E. et al.Brachytherapy for prostate cancer Endorectal MR imaging of local treatment-related changes.Radiology. 2001; 219: 817-821Crossref PubMed Scopus (94) Google Scholar) and rectal coil-based MRI spectroscopy (15Mizowaki T. Cohen G.H. Fung A.Y. et al.Towards integrating functional imaging in the treatment of prostate cancer with radiation The registration of the MR spectroscopy imaging to ultrasound/CT images and its implementation in treatment planning.Int J Radiat Oncol Biol Phys. 2002; 54: 1558-1564Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar, 16Zelefsky M.J. Cohen G. Zakian K.L. et al.Intraoperative conformal optimization for transperineal prostate implantation using magnetic resonance spectroscopic imaging.Cancer J. 2000; 6: 249-255PubMed Google Scholar) or ultrasound. Rectal probe–based studies attempt to improve definition of cancer vs. normal prostate, but lead to anatomic distortion of prostate and surrounding tissue contours. The current review attempts to define the key relationships in and around the prostate under physiologic and treatment position conditions.A final barrier is the meaning of “functional” anatomy. Urologists use a variety of tests to evaluate function, and function is not always predicted by anatomy. For example, lower urinary tract obstructive symptoms are associated with prostate hypertrophy but do not necessarily correlate with hypertrophy. Obstruction may be associated with a “tight bladder neck” without hypertrophy, whereas a massively hypertrophied gland may cause no obstructive symptoms. The current review does not include a review of functional testing and, for the most part, functional anatomy refers to the accepted normal physiologic role of a structure.Despite these barriers, the basic structure and physiology of the pelvic region are defined sufficiently to be useful to radiation oncologists. In an era of improved sophistication of treatment planning, the barrier to progress is the ability to understand the function and imaging of critical structures that are adjacent to the prostate. Including such structures in the treatment planning process where cost functions can be assigned to individual structures will allow dose limitation and improve quality of life outcomes without compromising cure rates.Methods and materialsRadiographic studiesAxial CT scans were obtained with 2-mm slice thickness. T2 MRI images (Echo Time [TE] = 96 ms, Repetition Time [TR] = 4500 ms) were obtained with a pelvic coil in axial, coronal, and sagittal planes with a 3-mm slice thickness. In addition, a time-of-flight MRI angiography sequence was obtained to define the internal pudendal artery (IPA).Data set registration using mutual informationThe coronal, sagittal, and MRI angiogram data sets were registered independently to the axial MRI data set. Starting points were selected and mutual information between data sets was maximized. Intensity information for the two data sets being registered was used; contour information was not considered. No image cropping was necessary for the registration of coronal or sagittal MRI to axial MRI data sets because the scans were taken in succession. Visual inspection of the prostate and surrounding structures was used to judge the acceptability of the registrations.To register the axial MRI to the CT data set, the same program was used. The axial MRI data set was cropped to limit the volume of interest for the registration process, improving the likelihood of a successful registration. Because the two scans were taken during separate sessions, it was possible for the prostate to have shifted relative to surrounding bone anatomy, external surfaces, or other anatomic structures such as the bladder and rectum. The axial MRI was cropped to exclude the external surface; additional cropping of bone, rectum, or bladder was implemented if the prostate appeared shifted relative to one or more of these structures. The same method was used to determine the acceptability of registration as was used for the MRI data sets. The axial MRI to CT registration matrix was then used to register the axial, sagittal, coronal, and angiogram MRI data sets to the CT data set.Comparison of structuresLiterature on the function and terminology of the prostate and surrounding anatomy was reviewed for clarification. Structures reviewed included prostate zonal anatomy (transition zone, peripheral zone, central zone and anterior fibromuscular stroma zone), bladder neck, preprostatic (internal) sphincter, external sphincter, GUD, corpus spongiosum (penile bulb), CC, IPA, NVB, cavernosal nerves, and seminal vesicles. Because of the critical role of the rectum in treatment planning, the anatomy specific to the prostate-rectum interface was reviewed as well. These structures were located and reviewed on the MRI, CT, and, when relevant, ultrasound data sets. Data set registration allowed for structures contoured on any of the MRI data sets to be displayed on the CT data set and for CT-defined structures to be displayed on any of the MRI data sets.ResultsProstate zonal anatomyIn younger men, four zones (Fig. 1) can be defined within the prostate: peripheral zone (PZ), transition zone (TZ), central zone (CZ), and anterior fibromuscular stroma (AFS) zone (17McLean J.E. The zonal anatomy of the prostate.Prostate. 1981; 2: 35-49PubMed Google Scholar) (Fig. 1a). The CZ surrounds the ejaculatory ducts. The anterior fibromuscular stroma is an anterior band of fibromuscular tissue contiguous with the bladder muscle and the external sphincter. The TZ is central and less prominent in younger men, but hypertrophies with age to become the dominant zone. With hypertrophy (Fig. 1b), all other zones are compressed and the CZ “peri-ejaculatory duct zone” can no longer be defined as distinct from the PZ. The TZ, PZ, and the AFS are clearly defined on T2 MRI (Fig. 2A). Although the PZ and TZ are visible on ultrasound, the AFS is not well defined (Fig. 2B). Zonal anatomy is poorly defined on CT.Fig. 2Zonal anatomy of the prostate. Transition zone and peripheral zone on (a) T2 magnetic resonance imaging and (b) ultrasound. AFS = anterior fibromuscular stroma; PZ = peripheral zone; TZ = transition zone.View Large Image Figure ViewerDownload (PPT)Zonal anatomy has replaced lobar anatomy with one exception. The term “median lobe” was originally designated as a third lobe occasionally palpable on digital examination above and between the two lateral lobes (Fig. 1b). On cystoscopy, the median lobe is visualized as posterior encroachment, as opposed to lateral encroachment from TZ hypertrophy. The median lobe is visible on ultrasound, MRI, and CT as a distinct form of hypertrophy with a large intralumen component (Fig. 1). It is important to note there is no median lobe zone in the zonal anatomy nomenclature, and the origin of the median lobe is unclear. Histologically, it is indistinguishable from TZ hypertrophy, with varying proportions of fibrous, glandular, and muscle tissue. It may originate from the TZ or periurethral stroma. The median lobe has unique behavior, and its presence has implications to radiation treatment planning and treatment selection (see Discussion).Overview of critical pathwaysThree major vascular and neural pathways near the prostate are defined in Fig. 3. The first is the posterolateral, which includes the NVB. These vessels and nerves course over the lateral rectal surface and are posteriorly and laterally adjacent to the seminal vesicle and superior prostate. They course inferior along the posterolateral surface of the prostate and through the GUD. The second pathway is the inferolateral pathway. Unlike the posterolateral pathway, vessels and nerves in this pathway do not come in contact with the prostate. Included in the inferolateral pathway is the IPA and inferolateral pathway nerve. The third pathway is the anteroinferior pathway consisting of the dorsal venous complex, which courses over the anterior prostate from the inferior direction.Fig. 3Nerve and vascular pathways. The posterolateral (PL) pathway proceeds from superior (seminal vesicle) and along the posterior lateral prostate and pierces the genitourinary diaphragm (GUD) lateral to the urethra. The inferior lateral (IL) proceeds from posterior through the GUD and includes the internal pudendal artery and nerve. The anterior inferior (AI) proceeds under the pubic symphysis and over the anterior prostate surface and includes the dorsal venous complex.View Large Image Figure ViewerDownload (PPT)Genitourinary functional anatomy: bladder neck and preprostatic sphincterAt the base of the bladder, the internal longitudinal layer of bladder muscle converges and merges with the inner longitudinal muscle of the internal or preprostatic sphincter (Fig. 1a). The term preprostatic is confusing because the preprostatic urethra and preprostatic sphincter extend into the prostate to the verumontanum. The designation preprostatic is from the transitional epithelium covering the preprostatic urethra. Thus the bladder (as defined by transitional epithelium) effectively extends into the prostate. The preprostatic sphincter is an involuntary sphincter composed of smooth muscle fibers, which play a role in maintenance of urinary continence as well as playing a key role by preventing retrograde ejaculation (18Brooks J.D. Chao W.M. Kerr J. Male pelvic anatomy reconstructed from the visible human data set.J Urol. 1998; 159: 868-872Abstract Full Text Full Text PDF PubMed Scopus (62) Google Scholar, 19Hinman Jr, F. Prostate and urethral sphincters.in: Hinman Jr., F. Atlas of urosurgical anatomy. W.B. Saunders Company, Philadelphia1993: 45-388Google Scholar, 20Oelrich T.M. The urethral sphincter muscle in the male.Am J Anat. 1980; 158: 229-246Crossref PubMed Scopus (213) Google Scholar, 21Elbadawi A. Mathews R. Light J.K. et al.Immunohistochemical and ultrastructural study of rhabdosphincter component of the prostatic capsule.J Urol. 1997; 158: 1819-1829Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar).The bladder, bladder neck, and preprostatic sphincter are continuous and therefore no line of demarcation is diagnostically apparent. T2 MRI defines bladder muscle well, but in the presence of TZ hypertrophy, the anatomy of the bladder neck is distorted because the TZ extends into and “obliterates” the bladder neck (18Brooks J.D. Chao W.M. Kerr J. Male pelvic anatomy reconstructed from the visible human data set.J Urol. 1998; 159: 868-872Abstract Full Text Full Text PDF PubMed Scopus (62) Google Scholar). The progressive changes in bladder neck/prostate interface are presented in Fig. 4.Fig. 4Change in base anatomy with transition zone (TZ) enlargement. (a) A distinct bladder neck is apparent. With progressive TZ enlargement, the bladder neck is effaced by TZ enlargement (b, c). The most extreme change is median lobe enlargement (d) with associated ball valve obstruction.View Large Image Figure ViewerDownload (PPT)Genitourinary functional anatomy: external sphincterThe external sphincter, also called the prostatomembranous sphincter, contains both the membranous urethral sphincter, surrounding the urethra in the GUD, and the prostatic sphincter, extending from the verumontanum to the prostate apex (19Hinman Jr, F. Prostate and urethral sphincters.in: Hinman Jr., F. Atlas of urosurgical anatomy. W.B. Saunders Company, Philadelphia1993: 45-388Google Scholar, 20Oelrich T.M. The urethral sphincter muscle in the male.Am J Anat. 1980; 158: 229-246Crossref PubMed Scopus (213) Google Scholar). There are three muscle types contributing to the external sphincter; smooth muscle, slow twitch, and fast twitch skeletal muscle (21Elbadawi A. Mathews R. Light J.K. et al.Immunohistochemical and ultrastructural study of rhabdosphincter component of the prostatic capsule.J Urol. 1997; 158: 1819-1829Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar). Skeletal muscle forms an omega-shaped sling termed the rhabdosphincter (22Strasser H. Frauscher F. Helweg G. et al.Transurethral ultrasound Evaluation of anatomy and function of the rhabdosphincter of the male urethra.J Urol. 1998; 159: 100-105Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 23Hollabaugh Jr, R.S. Dmochowski R.R. Steiner M.S. Neuroanatomy of the male rhabdosphincter.Urology. 1997; 49: 426-434Abstract Full Text PDF PubMed Scopus (166) Google Scholar, 24Strasser H. Bartsch G. Anatomy and innervation of the rhabdosphincter of the male urethra.Semin Urol Oncol. 2000; 18: 2-8PubMed Google Scholar). The slow twitch component is capable of sustained contraction. Along with the smooth muscle component, slow twitch fibers are responsible for passive or involuntary continence. The fast twitch component is controlled by branches of the pudendal nerve and is responsible for voluntary control of continence. The external sphincter can easily be seen on T2 MRI and varies in both length and thickness (Figs. 5a and 5b, coronal). In addition, the GUD, which surrounds the membranous sphincter, varies in length and thickness and is visible on T2 MRI as well. The detail of the GUD is presented in Figs. 5c–f.Fig. 5Genitourinary diaphragm. Variation in thickness of the genitourinary diaphragm (GUD) (a, b). Levels of GUD from apex to penile bulb (c–f).View Large Image Figure ViewerDownload (PPT)Urethral segmentsUrethral segments are defined by the zone or structure the urethra passes through. The preprostatic urethra is adjacent to the preprostatic sphincter. The prostatic urethra courses from the verumontanum to the GUD. The membranous urethra courses through the GUD and is surrounded by the external sphincter. The bulbar urethra passes through the penile bulb, which is continuous with the corpus spongiosum (penile urethra). There are two points of angulation of the urethra. Within the prostate, at the verumontanum, the urethra bends 30–40° anterior. Within the penile bulb, the urethra bends at a 30° angle, a common point of stricture formation unrelated to radiation.Erection functional anatomy: IPA, NVB, and CCThe IPA originates from the internal iliac and passes through the pudendal canal. It supplies three main arteries of the penis: the bulbo-urethral artery, the cavernous or deep artery, and the dorsal artery. These branch as the IPA passes through the GUD (25Benson G.S. Erection, emission, and ejaculation Physiologic mechanisms.in: Lipshultz L. Howard S.S. Infertility in the male. 3rd ed. Mosby-Year Book Inc, St. Louis1997: 155-172Google Scholar, 26Johnson D.E. Costello A.J. Anatomy of the penis and groin.in: Raghavan D. Scher H.I. Leibel S.A. Lange P.F. Principles and practice of genitourinary oncology. Lippincott-Raven Publishers, Philadelphia1997: 913-920Google Scholar, 27Brooks J.D. Anatomy of the lower urinary tract and male genitalia.in: Walsh P.C. Retik A.B. Vaughan Jr, E.D. Wein A.J. Campbell’s urology. 8th ed. Saunders, Philadelphia2002: 41-81Google Scholar). The deep artery of the penis follows the center of the CC and supplies increased blood flow to these tissues during penile erection. The dorsal artery of the penis courses above the corpus spongiosum and between the corpus cavernosa. The bulbo-urethral artery supplies the penile bulb.The IPA can be defined by a noncontrast MRI time-of-flight sequence (Fig. 6). The terminal branches of the IPA (dorsal artery, deep artery, and bulbo-urethral artery) are not well visualized on a time-of-flight sequence. The distal IPA can be traced to the CC by a combination of time-of-flight sequence and coronal T2 MRI. It is possible in most patients to define the course of the entire IPA by T2 MRI alone, although the patency of the vessel is not disclosed by this technique.Fig. 6Internal pudendal artery. (a) Magnetic resonance imaging (MRI) angio. (b) Axial MRI. (c) MRI angiogram registered to computed tomography.View Large Image Figure ViewerDownload (PPT)Corpus cavernosumThe erection expansile tissue is the corpus cavernosum. The base of the CC is surrounded by the ischiocavernosus muscle and relaxation of this muscle in concert with IPA dilation results in rapid filling of the CC. Because of the unique venous anatomy, the filling of the CC compresses the veins, limiting efflux. Erectile dysfunction can result from arterial insufficiency (e.g., IPA-occlusive disease is the most common cause of impotence), venous leak, or nerve dysfunction. The CC is visible on CT lateral to the penile bulb, but is more clearly defined by T2 MRI, where the muscle surrounding the base of the CC (crura) is visible as a distinct entity (Figs. 5a and 5b).Neurovascular bundleThe NVB follows a path between the prostate and rectum posterior and lateral to the prostate (Fig. 7a) and terminates in the cavernosal nerves. There are two cavernosal nerves (Fig. 3). The lesser cavernosal nerve passes through the GUD and terminates on the CC. A second cavernosal nerve, the greater cavernosal nerve, courses along the surface of the GUD and passes through the opening in the GUD just posterior to the pubic symphysis, through which the dorsal vein passes. The greater cavernosal nerve is not defined or addressed in the current nerve sparing prostatectomy literature (28Walsh P.C. Anatomic radical retropubic prostatectomy.in: Walsh P.C. Retik A.B. Vaughan Jr, E.D. Wein A.J. Campbell’s urology. 8th ed. Saunders, Philadelphia2002: 3107-3129Google Scholar). It is interesting to note that studies employing CaverMap (UroMed, Boston, MA), a nerve-stimulating device used to define the cavernosal nerves, were not considered specific in that 54% of patients stimulated away from the NVB had erections (29Walsh P.C. Marschke P. Catalona W.J. et al.Efficacy of first-generation Cavermap to verify location and function of cavernous nerves during radical prostatectomy A multi-institutional evaluation by experienced surgeons.Urology. 2001; 57: 491-494Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar). It is possible that greater cavernosal nerve stimulation contributed to such erections.Fig. 7Neurovascular bundle (NVB) and terminal branches. (a) Axial magnetic resonance imaging. (b) Three-dimensional reconstruction with cavernosal nerve defined by relationship to membranous urethra.View Large Image Figure ViewerDownload (PPT)The NVB adjacent to the prostate is visible on ultrasound (especially color Doppler), CT, and T2 MRI (Fig. 7a). The average diameter of the terminal branches (cavernosal nerves) of the NVB is 0.12 mm (30Myers R.P. Gross and applied anatomy of the prostate.in: Kantoff P.W. Carroll P.R. D’Amico A.V. Prostate cancer principles and practice. Lippincott Williams & Wilkins Publishers, Philadelphia2002: 3-15Google Scholar, 31Yang C.C. Bradley W.E. Innervation of the human glans penis.J Urol. 1999; 161: 97-102Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar). Because of this small diameter, the nerves themselves cannot be seen on T2 MRI. The path of the lesser cavernosal nerve can be approximated based on its relationship to the membranous urethra (Fig. 7b). At the prostate apex, the lesser cavernosal nerve is located at the 5 and 7 o’clock positions, relative to the urethra. I" @default.
• W2014920995 created "2016-06-24" @default.
• W2014920995 creator A5003047411 @default.
• W2014920995 creator A5018226548 @default.
• W2014920995 creator A5018511777 @default.
• W2014920995 creator A5056257547 @default.
• W2014920995 creator A5060037809 @default.
• W2014920995 creator A5076002647 @default.
• W2014920995 creator A5086576471 @default.
• W2014920995 date "2005-10-01" @default.
• W2014920995 modified "2023-10-10" @default.
• W2014920995 title "Functional anatomy of the prostate: Implications for treatment planning" @default.
• W2014920995 cites W142283833 @default.
• W2014920995 cites W1582880225 @default.
• W2014920995 cites W1964572317 @default.
• W2014920995 cites W1970630888 @default.
• W2014920995 cites W1981964144 @default.
• W2014920995 cites W1982618467 @default.
• W2014920995 cites W1983412795 @default.
• W2014920995 cites W1984209823 @default.
• W2014920995 cites W1986614041 @default.
• W2014920995 cites W1988003121 @default.
• W2014920995 cites W1989652485 @default.
• W2014920995 cites W1991557114 @default.
• W2014920995 cites W1992213600 @default.
• W2014920995 cites W2003662012 @default.
• W2014920995 cites W2007513615 @default.
• W2014920995 cites W2011084131 @default.
• W2014920995 cites W2013813241 @default.
• W2014920995 cites W2013943547 @default.
• W2014920995 cites W2015071129 @default.
• W2014920995 cites W2016453130 @default.
• W2014920995 cites W2023406850 @default.
• W2014920995 cites W2025348847 @default.
• W2014920995 cites W2025785329 @default.
• W2014920995 cites W2028320337 @default.
• W2014920995 cites W2030924064 @default.
• W2014920995 cites W2032809021 @default.
• W2014920995 cites W2034446231 @default.
• W2014920995 cites W2035032611 @default.
• W2014920995 cites W2036564302 @default.
• W2014920995 cites W2037964436 @default.
• W2014920995 cites W2044020773 @default.
• W2014920995 cites W2050043874 @default.
• W2014920995 cites W2051632366 @default.
• W2014920995 cites W2052197259 @default.
• W2014920995 cites W2057842796 @default.
• W2014920995 cites W2060445317 @default.
• W2014920995 cites W2065412214 @default.
• W2014920995 cites W2075810750 @default.
• W2014920995 cites W2077546766 @default.
• W2014920995 cites W2082648248 @default.
• W2014920995 cites W2090243182 @default.
• W2014920995 cites W2090469719 @default.
• W2014920995 cites W2112870348 @default.
• W2014920995 cites W2124530895 @default.
• W2014920995 cites W2128760486 @default.
• W2014920995 cites W2134199567 @default.
• W2014920995 cites W2137419415 @default.
• W2014920995 cites W2144841219 @default.
• W2014920995 cites W2145887747 @default.
• W2014920995 cites W2154492280 @default.
• W2014920995 cites W2155681686 @default.
• W2014920995 cites W2160817777 @default.
• W2014920995 cites W2164144700 @default.
• W2014920995 cites W2171367875 @default.
• W2014920995 cites W2402399220 @default.
• W2014920995 cites W2409682632 @default.
• W2014920995 cites W2415580910 @default.
• W2014920995 doi "https://doi.org/10.1016/j.ijrobp.2005.02.036" @default.
• W2014920995 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/16168840" @default.
• W2014920995 hasPublicationYear "2005" @default.
• W2014920995 type Work @default.
• W2014920995 sameAs 2014920995 @default.
• W2014920995 citedByCount "91" @default.
• W2014920995 countsByYear W20149209952012 @default.
• W2014920995 countsByYear W20149209952013 @default.
• W2014920995 countsByYear W20149209952014 @default.
• W2014920995 countsByYear W20149209952015 @default.
• W2014920995 countsByYear W20149209952016 @default.
• W2014920995 countsByYear W20149209952017 @default.
• W2014920995 countsByYear W20149209952018 @default.
• W2014920995 countsByYear W20149209952019 @default.
• W2014920995 countsByYear W20149209952020 @default.
• W2014920995 countsByYear W20149209952021 @default.
• W2014920995 countsByYear W20149209952022 @default.
• W2014920995 countsByYear W20149209952023 @default.
• W2014920995 crossrefType "journal-article" @default.
• W2014920995 hasAuthorship W2014920995A5003047411 @default.
• W2014920995 hasAuthorship W2014920995A5018226548 @default.
• W2014920995 hasAuthorship W2014920995A5018511777 @default.
• W2014920995 hasAuthorship W2014920995A5056257547 @default.
• W2014920995 hasAuthorship W2014920995A5060037809 @default.
• W2014920995 hasAuthorship W2014920995A5076002647 @default.
• W2014920995 hasAuthorship W2014920995A5086576471 @default.
• W2014920995 hasConcept C105702510 @default.
• W2014920995 hasConcept C121608353 @default.
• W2014920995 hasConcept C126322002 @default.

• next