Prostate MRI anatomy from UNIVERSITY OF MICHIGAN

Prostate MRI anatomy
UNIVERSITY OF MICHIGAN

1. Atlas of T2 MRI Prostate Anatomy with CT Correlation Patrick McLaughlin, MD, Sara Troyer, BS, Sally Berri, MS, George Hixson, Amichay Meirovitz, MD, Peter Roberson, PhD, Vrinda Narayana, PhD

2. Table of Contents: • Introduction ………3 • Zonal Anatomy ………5 • Part 1: Overview of T2 MRI scans……... 9 patient 1………10 patient 2………27 patient 3………42 patient 4………62 • Part 2: Variations in Prostate Anatomy………78 Section 1: Variations in TZ size………79 Section 2: Base/Bladder Interface Variations………83 Section 3: Prostate Apex/GUD variations………106 • Part 3: Post-prostate implant distortion of anatomy 141 Mild Distortion ………142 Moderate Distortion………151 Severe Distortion ………160 • Part 4: Contouring the prostate on MRI and CT ……… 172 Pre implant Scans ………173 Post implant Scans ………212

3. Introduction The following prostate atlas will serve several purposes.  First, it is a review of pelvic MRI anatomy.  T2 pelvic scans disclose details of prostate anatomy as well as anatomy of adjacent critical structures with much greater detail than CT scans.  It is likely that MRI-based planning will ultimately replace CT scanning due to this clarity and a review of the details of prostate associated anatomy will be useful. A second goal is to improve CT contouring of the prostate.  We have noted that with increased experience with MRI scans CT defined prostate volumes begin to approach MRI defined volumes.  There are also a number of clues on registered images that allow improved interpretation when CT alone is available.  The CT scans in the atlas were obtained on a CT simulator without contrast.  They would not be considered diagnostic level CT scans in the current era.  In some respects, the lack of clarity serves the atlas well.  In spite of the limited detail, it is possible to contour the prostate on the basis of adjacent anatomy defined on CT.    The atlas was created from multiple patients registered with MRI and CT data sets.  The atlas includes both post implant scans and non-implant scans. 

4. For the registration portion, CT scans were obtained on a helical scanner in 2 or 3 mm intervals.  MRIs were obtained in axial, sagittal, and coronal planes.  These three MRI data sets were then fused by mutual information.  A composite prostate was generated.  The composite is not a sum total of areas of agreement of coronal, sagittal, and axial.  Instead, the scan that clarified an individual region was weighed more heavily than the scans in which a region was not well defined.  For example, at the apex, the coronal scan unambiguously defines the apex due to the clear interface of the GUD and prostate apex.  Therefore, disagreements at the apex were settled in favor of the coronal defined apex.  At the base, the sagittal view can be extremely useful in distinguishing the prostate from bladder and seminal vesicle.  At mid-gland, there was excellent agreement between the three MRI data sets.  When the MRI is projected on the CT scan to instruct in contouring of the CT images, the projected contour is from the composite prostate rather than the axial.  It has been projected, in many cases, on the axial MRI for reference.  The second half of the teaching module following MRI anatomy, MRI-CT correlation, is an interactive test module.  In this “Prost-A-Doodle” module a CT image is presented, a contour can be entered, followed by review of the registered MRI image.  The MRI contour can then be projected on the CT to allow a back and forth interactive experience.  This module includes both non-implant and implant patients as well.  

5. Zonal Anatomy • Zonal anatomy refers to radiographically or histologically distinct regions within the prostate. The initial description and definition was by McLean and based on ultrasound defined regions. • 4 major zones are visible in young men - Peripheral zone (PZ) - Central zone - peri-ejaculatory duct zone(CZ) - Transition zone (TZ) - Anterior fibromuscular stroma (AFS) • In the following figure the left image depicts the zonal anatomy of a younger male. With age hypertrophy of the TZ may occur , compressing the CZ. This change is depicted in the right figure.

6. Zonal Anatomy of the Prostate

7. Zonal Anatomy of the prostate can be confusing due to different uses of the word “central zone”.  One use of “central zone” is in reference to the region immediately around the ejaculatory ducts posterior to the urethra (McLean). This is visible on ultrasound in young men, but TZ hypertrophy (BPH) compresses the central zone and it is not visible as a distinct zone in older men. Ironically the central, peri-ejaculatory duct zone merges with the peripheral zone (PZ) after TZ hypertrophy. A second use of the term “central” is in reference to TZ hypertrophy. This informal use may appear in ultrasound or radiology reports but creates confusion. Two solutions to the ambiguous nomenclature are available. One solution is to abandon the term central completely, because the central zone is not visible in most prostate cancer patients. TZ is used to refer to the zone of hypertrophy. A second solution divides the prostate into inner, outer, and anterior fibromuscular zones, the schema outlined by Matthew Rifkin in Ultrasound of the Prostate (Lippincott-Raven) . The inner zone includes the TZ and periurethral stroma. The outer zone includes the PZ and the central or peri-ejaculatory duct zone.    Zonal Anatomy

8. In this atlas the term central will be avoided, and TZ, PZ, and AFS will be used to define the prostate zones. Zonal anatomy has replaced lobar anatomy with one exception. The term median lobe hypertrophy refers to a distinct form of hypertrophy noted on digital exam as a third lobe palpable between the two lateral lobes . On cystoscopy and radiographically median lobe hypertrophy extends into the bladder lumen . In some the median lobe hypertrophy is comparable in size to the entire remaining prostate. It may cause obstruction by a ball valve mechanism in which the hypertrophied tissue folds over the urethral opening. Unlike TZ hypertrophy and BPH, there is no zonal anatomy correlate for the median lobe. The actual origin of the median lobe may be posterior TZ or peri-urethral stroma. Histologically it is not distinct from TZ. In the prior schematic it is presented as originating from the peri-urethral stroma (right figure), but its actual origin is uncertain. Zonal Anatomy

9. Part 1: Overview of T2 MRI scans on pre-prostate implant patients

10. Axial T2 MRI Images Patient 1:

11. Image 1 Image 2 Patient 1, Axial T2 MRI Crura of Corpus Cavernosa Penile Bulb Urethra Rectum Level: Penile Bulb

12. Image 3 Image 4 Patient 1, Axial T2 MRI Rectum Note the penile bulb ends and the GU Diaphragm (GUD) begins. Urethra Level: Penile Bulb/ GUD transition

13. Image 5 Image 6 Patient 1, Axial T2 MRI Rectum GUD Urethra Urethra Pudendal Canal External Sphincter External Sphincter Level: GUD Note the thickness of the External Sphincter muscle. The circular shape of the GUD suggests prostate but this is still 1 cm below the prostate. Also note the Pudendal Canal is clear near the GUD level.

14. Image 7 Image 8 Patient 1, Axial T2 MRI Rectum GUD Note the convex shape of the Levator Ani at the upper GUD (Image 7). On image 8 the concave shape of the Levator Ani marks the transition to the prostate apex. External Sphincter External Sphincter Level : GUD Levator Ani muscle

15. Image 9 Image 10 Patient 1, Axial T2 MRI Rectum Prostate apex Note the external sphincter commonly extends into the prostate apex. prostate External Sphincter Level: Prostate Apex Levator Ani muscle

16. Image 11 Image 12 Patient 1, Axial T2 MRI Rectum prostate Obturator Internus Obturator Internus Level: Mid-Prostate Levator Ani muscle AFS

17. Image 13 Image 14 Patient 1, Axial T2 MRI Rectum PZ Note the TZ is visible in images 13 and 14 (also on image 12). TZ Bladder muscle / Bladder neck Level: Prostate Base

18. Image 15 Image 16 Patient 1, Axial T2 MRI Rectum prostate Bladder Muscle Bladder Muscle Seminal vesicles Note in image 16 the prostate base merges with the root of the seminal vesicles. Level: Prostate Base

19. Image 17 Patient 1, Axial T2 MRI Rectum Bladder Muscle Level: Prostate Base / Seminal Vesicle transition Seminal vesicles Image 18

20. Coronal T2 MRI Images Patient 1:

21. Image 2 Image 1 Patient 1, Coronal T2 MRI Crura of Corpus Cavernosa Pudendal Canal prostate Seminal vesicles GUD Penile Bulb Levator Ani muscle External Sphincter Prostate apex The distance between the prostate apex and the penile bulb is visible on the coronal images. Also note, the external sphincter extends through the GUD and into the prostate. Level: Mid-Prostate

22. Image 3 Image 4 Patient 1, Coronal T2 MRI Crura of Corpus Cavernosa prostate Lower Sphincter Penile Bulb Urethra Levator Ani muscle Level: Mid / Anterior Prostate

23. Image 5 Patient 1, Coronal T2 MRI prostate Crura of Corpus Cavernosa Penile Bulb/ Corpus Spongiosum Level: Anterior Prostate

24. Sagittal T2 MRI Images Patient 1:

25. Image 1 Image 2 Patient 1, Sagittal T2 MRI Seminal vesicles prostate Seminal vesicles Level: Lateral Prostate Levator Ani Muscle Pubic Symphysis

26. Image 3 Image 4 Patient 1, Sagittal T2 MRI Seminal vesicles prostate Urethra Penile Bulb Rectum Rectum Penile Bulb Seminal vesicles Note the urethra is visible through the center of the prostate in image 4. Also, the definition of the apex is less distinct on sagittal than on coronal. Sagittal views often clarify the prostate base/ seminal vesicle region. Level: Mid-Prostate AFS

27. Axial T2 MRI Images Patient 2:

28. Image 1 Image 2 Patient 2, Axial T2 MRI Rectum Penile Bulb Crura of Corpus Cavernosa Urethra Level: Penile Bulb

29. Image 3 Image 4 Patient 2, Axial T2 MRI Urethra In image 3, the penile bulb ends and the GUD begins . In image 4, the pudendal canals become clear. Rectum GUD External Sphincter Pudendal Canal Level: Inferior GUD

30. Image 5 Image 6 Patient 2, Axial T2 MRI External Sphincter GUD Rectum Pudendal Canal Rectum Level: GUD

31. Image 7 Image 8 Patient 2, Axial T2 MRI Rectum Prostate Note the TZ becomes clear near the center of the prostate- image 8 Obturator internus Level: Apex to Mid-Prostate TZ AFS

32. Image 9 Image 10 Patient 2, Axial T2 MRI Prostate Bladder Muscle Rectum Obturator internus Note the clarity of the rectal muscle/ rectal wall. Level: Mid-Prostate AFS

33. Image 11 Image 12 Patient 2, Axial T2 MRI Prostate Rectum Bladder Muscle Level: Prostate Base

34. Image 13 Image 14 Patient 2, Axial T2 MRI Prostate Rectum Bladder Muscle Notice the prostate base in images 12-14. Level: Prostate Base

35. Image 15 Patient 2, Axial T2 MRI Seminal vesicles transition Rectum Level: Prostate Base / Seminal Vesicle Transition Seminal vesicles Image 16

36. Coronal T2 MRI Images Patient 2:

37. Image 1 Image 2 Patient 2, Coronal T2 MRI Prostate Penile Bulb Urethra Crura of Corpus Cavernosa External Sphincter GUD Pudendal Canal Prostate apex Seminal vesicles Levator Ani muscle Note the distance between the prostate apex and the penile bulb on coronal MRI. Level: Mid-Prostate Pubis

38. Image 3 Image 4 Patient 2, Coronal T2 MRI Prostate Penile Bulb Crura of Corpus Cavernosa External Sphincter GUD Crura of Corpus Cavernosa Level: Anterior Prostate

39. Sagittal T2 MRI Images Patient 2:

40. Image 1 Image 2 Patient 2, Sagittal T2 MRI Penile Bulb Rectum Urethra External Sphincter Seminal vesicles Seminal vesicles Rectum Sagittal image 2 cuts though the center of the prostate showing the urethra. Note the significant base extension posterior to the bladder. Also note that the anterior fibromuscular stroma is contiguous with the bladder muscle and external sphincter. Level: Mid-Prostate AFS Pubic symphysis

41. Image 3 Image 4 Patient 2, Sagittal T2 MRI Prostate Rectum Seminal vesicles Rectum Seminal vesicles Level: Lateral Prostate

42. Axial T2 MRI Images Patient 3:

43. Image 1 Image 2 Patient 3, Axial T2 MRI Penile Bulb Rectum Urethra Level: Penile Bulb

44. Image 3 Image 4 Patient 3, Axial T2 MRI Rectum Urethra External Sphincter GUD Pudendal Canal Note the pudendal canals in image 4. Level: Inferior GUD

45. Image 5 Image 6 Patient 3, Axial T2 MRI Rectum External Sphincter GUD Pudendal Canal Rectum Level: GUD

46. Image 7 Image 8 Patient 3, Axial T2 MRI Prostate Rectum Pudendal Canal Level: Prostate Apex

47. Image 9 Image 10 Patient 3, Axial T2 MRI Prostate Rectum The TZ is visible in image 9. Obturator internus Level: Mid-Prostate TZ TZ

48. Image 11 Image 12 Patient 3, Axial T2 MRI Prostate Rectum Level: Mid-Prostate TZ

49. Image 13 Image 14 Patient 3, Axial T2 MRI Prostate Rectum Level: Prostate Base Note the hypertrophy extends into the bladder lumen. Such hypertrophy has a distinct shape referred to as a “median lobe”. Median Lobe Median Lobe

50. Image 15 Image 16 Patient 3, Axial T2 MRI Prostate Rectum Seminal vesicles Seminal vesicles The defining feature of a median lobe is a “dolphin nose” projection into the bladder, see coronal view image 6 and sagittal view image 4. Level: Prostate Base Median Lobe Median Lobe

51. Image 17 Image 18 Patient 3, Axial T2 MRI Prostate Rectum Seminal vesicles Level: Prostate Base Median Lobe Median Lobe

52. Image 19 Image 20 Patient 3, Axial T2 MRI Prostate Rectum Seminal vesicles Level: Prostate Base/ Seminal Vesicles Median Lobe Median Lobe

53. Coronal T2 MRI Images Patient 3:

54. Image 1 Image 2 Patient 3, Coronal T2 MRI Prostate Penile Bulb Crura of Corpus Cavernosa External Sphincter GUD Levator Ani muscle Level: Mid-Prostate

55. Image 3 Image 4 Patient 3, Coronal T2 MRI Prostate Penile Bulb Urethra Crura of Corpus Cavernosa External Sphincter GUD Prostate apex Levator Ani muscle Notice the median lobe as it pushes into the bladder in coronal images 4-7. Obturator internus Level: Mid-Prostate

56. Image 5 Image 6 Patient 3, Coronal T2 MRI Prostate Penile Bulb Urethra Crura of Corpus Cavernosa Level: Anterior Prostate Median Lobe

57. Image 7 Patient 3, Coronal T2 MRI Prostate Penile Bulb Crura of Corpus Cavernosa Level: Anterior Prostate Median Lobe

58. Sagittal T2 MRI Images Patient 3:

59. Image 1 Image 2 Patient 3, Sagittal T2 MRI Prostate Penile Bulb Rectum Seminal vesicles Seminal vesicles Rectum Notice the median lobe in Sagittal images 2-5. Level: Lateral Prostate Median Lobe

60. Image 3 Image 4 Patient 3, Sagittal T2 MRI Prostate Penile Bulb Rectum Urethra External Sphincter Seminal vesicles Penile Bulb Rectum Seminal vesicles Notice the urethra in image 4 is not visible through the center of the prostate, however, it is visible below the prostate. Level: Mid-Prostate Median Lobe Median Lobe

61. Image 5 Patient 3, Sagittal T2 MRI Prostate Rectum Seminal vesicles Level: Lateral Prostate Median Lobe

62. Axial T2 MRI Images Patient 4:

63. Image 1 Image 2 Patient 4, Axial T2 MRI Penile Bulb Rectum Urethra Level: Penile Bulb

64. Image 4 Image 3 Patient 4, Axial T2 MRI Rectum Urethra External Sphincter GUD Level: GUD

65. Image 6 Image 5 Patient 4, Axial T2 MRI Prostate Rectum External Sphincter Pudendal Canal Prostate apex The prostate apex begins in image 5. Level: Prostate Apex

66. Image 8 Image 7 Patient 4, Axial T2 MRI Prostate Rectum Pudendal Canal Note the TZ and PZ are visible in image 8. Obturator internus Level: Mid-Prostate TZ PZ

67. Image 10 Image 9 Patient 4, Axial T2 MRI Prostate Rectum Bladder Muscle Bladder Muscle Level: Mid-Prostate TZ

68. Patient 4, Axial T2 MRI Image 12 Image 11 Prostate Rectum Bladder Muscle Seminal vesicles Note the hypertrophy causes the prostate to protrude into the bladder creating a median lobe. This is seen in images 11-14. Level: Prostate Base Median Lobe Median Lobe

69. Image 14 Image 13 Patient 4, Axial T2 MRI Prostate Rectum Bladder Muscle Seminal vesicles Bladder Muscle Seminal vesicles Level: Prostate Base / Seminal Vesicle Interface Median Lobe

70. Coronal T2 MRI Images Patient 4:

71. Image 1 Image 2 Patient 4, Coronal T2 MRI Prostate Penile Bulb External Sphincter GUD Pudendal Canal Note the pudendal canals on Coronal MRI image 2. Obturator internus Level: Mid-Prostate

72. Image 3 Image 4 Patient 4, Coronal T2 MRI Prostate Penile Bulb Crura of Corpus Cavernosa External Sphincter GUD Prostate apex Levator Ani muscle Note the TZ is clearly visible in Coronal MRI image 3. Also notice the short distance between the prostate apex and penile bulb. Level: Mid-Prostate TZ

73. Image 5 Image 6 Patient 4, Coronal T2 MRI Prostate Penile Bulb Urethra Crura of Corpus Cavernosa GUD Images 5-7 show the median lobe pushing into the bladder. Level: Anterior Prostate Median Lobe Median Lobe

74. Image 7 Patient 4, Coronal T2 MRI Prostate Penile Bulb Urethra Crura of Corpus Cavernosa Level: Anterior Prostate Median Lobe

75. Sagittal T2 MRI Images Patient 4:

76. Image 1 Image 2 Patient 4, sagittal T2 MRI Prostate Penile Bulb Rectum Urethra Seminal vesicles Rectum Penile Bulb Seminal vesicles In Image 1 the urethra is visible through the center of the prostate. The median lobe can also be seen in sagittal images 1-2. Level: Mid-Prostate Median Lobe Median Lobe

77. Image 3 Image 4 Patient 4, sagittal T2 MRI Prostate Penile Bulb Rectum Seminal vesicles Seminal vesicles Rectum Note the visible TZ on sagittal MRI in images 3-4. Level: Lateral Prostate TZ

78. Part 2: Variations in Prostate Anatomy T2 MRI Axial, Coronal, and Sagittal Pre-Implant scans

79. Variations in TZ Size Pre-prostate implant T2 MRI scans Part 2, Section 1

80. Patient 5-medium sized TZ prostate rectum Axial Prone Image Axial Prone Image TZ

81. Patient 6-large TZ Axial Supine Image Coronal Image prostate rectum TZ

82. Patient 7 Notice the large TZ accounts for most of the prostate volume. prostate rectum Axial Supine Image Axial Supine Image TZ

83. Base/ Bladder Interface Variations Part 2, Section 2

84. Distinct Bladder neck Mid-Sagittal MRI Prior to prostate hypertrophy the bladder neck muscle is visibly distinct. Often in patients with small glands, little BPH, a distinct bladder neck muscle can be seen connecting the bladder and the prostate. This muscle often extending into the prostate as seen above. The internal sphincter is a direct extension of bladder neck muscle into the prostate.

85. Partially obliterated bladder neck As the prostate begins to hypertrophy the bladder neck muscle becomes less distinct. Often, in this stage, muscle can be seen between the prostate and bladder but it does not extend into the prostate. Mid-Sagittal MRI

86. Obliterated bladder neck As hypertrophy continues the bladder neck muscle becomes ‘obliterated’ by the expanding prostate. Muscle can no longer be clearly seen between the prostate and bladder. Mid-Sagittal MRI

87. Median Lobe Hypertrophy A distinct form of hypertrophy, median lobe hypertrophy, results in a ‘dolphin-nose’ projection, originating from the posterior, projecting into the bladder lumen. It should be noted that there is no direct progression from BPH to median lobe hypertrophy. Mid-Sagittal MRI

88. Visible Bladder Neck 1 Bladder Neck AFS Mid-Sagittal This prostate has minimal hypertrophy and a visible bladder neck. The AFS can be seen merging with the bladder muscle. Axial MRI’s through the base are shown in the following slides.

89. Bladder Neck Bladder Neck Note the bladder neck takes on a circular shape as it attaches to the prostate. Image 1 Image 2 Image 3 Visible Bladder Neck 1

90. Bladder Neck merging with AFS The bladder neck merges with the AFS in images 4 and 5. Image 4 Image 5 Visible Bladder Neck 1

91. Bladder Neck Mid-Sagittal Visible Bladder Neck 2 This prostate also has a distinct bladder neck visible on sagittal MRI. Notice the appearance of this in the following axial scans.

92. Bladder Muscle Bladder Neck Bladder Neck Bladder Muscle Note the circular shape of the bladder neck as it attaches to the prostate. Also note the large amount of bladder muscle visible on the scans. Image 1 Image 2 Image 3 Visible Bladder Neck 2

93. Bladder Neck Image 4 Image 5 Visible Bladder Neck 2

94. Bladder Neck AFS Mid-Sagittal Visible Bladder Neck 3 This prostate also has a distinct bladder neck muscle.

95. Visible Bladder Neck 3 Bladder Neck Image 1 Image 2 Note the circular shape of attachment of muscle and prostate.

96. AFS Image 4 Bladder Neck merging with AFS Image 3 Visible Bladder Neck 3 Note the bladder neck muscle merges with the AFS.

97. Mid-Sagittal Obliterated bladder neck 1 Notice the displacement of the bladder neck muscle after prostate hypertrophy.

98. Obliterated bladder neck 1 Image 1 Image 3 Image 2

99. Image 4 Image 5 Obliterated bladder neck 1

100. Mid-Sagittal Obliterated bladder neck 2 Notice the prostate protruding into the bladder obliterating and displacing the bladder neck.

101. Obliterated bladder neck 2 Image 1 Image 2 Image 3

102. Image 5 Image 6 Obliterated bladder neck 2 Image 4

103. The median lobe enters the bladder from the posterior Mid-Sagittal Median lobe 1 The presence of a median lobe, while a distinct form of hypertrophy, also obliterates and displaces the bladder neck muscle.

104. Median lobe 1 Image 1 Image 3 Image 2

105. Image 4 Image 5 Median lobe 1

106. Prostate Apex / GUD Variations Pre-prostate implant T2 MRI scans Part 2, Section 3

107. Apex Definition  Axial MRI apex /GUD transition  Ultrasound apex/GUD transition  Penile Bulb (1.5 cm above penile bulb) rule condemned  Coronal MRI apex/GUD transition

108. Note the transition from concave levator ani at the apex versus convex just below the apex. MRI Apex to GUD Transition Concave levator ani Convex levator ani

109. Ultrasound Apex / GUD Transition Apex GUD Bulbourethral Gland Prostate The apex / GUD transition on ultrasound is clearly defined in this example. However in less clear examples the external sphincter may be contoured as prostate. Recognition of the light H-shaped GUD or Bulbourethral gland indicates GUD. external sphincter

110. MRI GUD Ultrasound GUD GUD on Ultrasound and MRI Note the similar shape of the GUD on MRI and ultrasound.

111. Penile Bulb Rule Condemned The distance between the prostate apex and penile bulb is highly variable. When measured on MRI with a sample size of 25 the distance is 1.33 (.32) cm with a range of 0.6 cm to 1.97 cm. Using the penile bulb rule ( the prostate apex is 1.5 cm above the penile bulb ) often results in underestimation of the prostate. Also the penile bulb / GUD interface may be obliterated post implant. (see part 3 of atlas) Coronal: Mid-Prostate Coronal: Mid-Prostate Coronal: Posterior Prostate

112. Summary of GUD Shape Note the change in shape of the GUD: just above the penile bulb it is triangular in shape, near the mid-diaphragm it is circular, then hourglass shaped. These shapes are often visible in subtle form on CT. Image 1. just above penile bulb Image 2 Image 3 Image 4. apex

113. Axial Prone Image Coronal Image External sphincter rectum prostate Penile bulb Pudendal canal GUD Coronal cross section Crura of corpus cavernosa Patient 8 Notice the circular shape of the GUD in the Axial image. The green line ( ) depicts the plane of the coronal image.

114. Patient 9 Axial Prone Image Coronal Image rectum Coronal cross section External sphincter GUD prostate Penile bulb Crura of corpus cavernosa Notice the separation between the prostate and penile bulb on the Coronal MRI.

115. Patient 10 Axial Prone Image Coronal Image rectum Coronal cross section External sphincter GUD prostate Penile bulb Pudendal canal

116. Patient 11 Axial Supine Image Coronal Image Coronal cross section External sphincter GUD prostate Penile bulb Pudendal canal Note the thickness of the external sphincter on coronal.

117. Patient 12 Axial Supine Image Coronal Image rectum Coronal cross section GUD prostate Penile bulb Pudendal canal Crura of corpus cavernosa Note the thin GUD and the minimal separation between the prostate and penile bulb.

118. Overview of CT and US contouring errors at the apex

119. Clarity, Obscuration, Clarity Problem: On CT as contouring proceeds inferior, the prostate is clear above the apex, unclear at the apex, and mistaken for elliptical or circular GUD elements below the apex GUD CT Mid-Prostate CT Prostate Apex Level CT GUD Level

120. A 3-dimensional view shows when prostate contours have included too much GUD. A lateral BEV can also be used to visualized this projection. 3 D View- contouring GUD as prostate - “pros-teat” rectum The same figure with the MRI prostate shown in light blue. 3D view of Prostate contoured on CT to include round GUD and external sphincter often mistaken for prostate. rectum GUD contoured as prostate

121. 3 D View- contouring prostate with rectum as reference - “love handle” A 3-dimensional view shows the prostate has been contoured in reference to the clearly visualized rectum, on the assumption the prostate is adjacent to the rectum . A lateral BEV can be used to visualize this overestimation. The posterior edge of the prostate is convex. When aligned to the rectum it appears concave . 3D view of Prostate contoured to the edge of the rectum on CT The same figure with the MRI prostate shown in light blue rectum rectum Prostate contoured to the edge of rectum

122. Patient 13: Visible GUD on CT-pre implant Axial CT 1 AxialT2 MRI 1 Axial CT 2 AxialT2 MRI 2 Penile Bulb Note directly superior to the penile bulb the CT is unclear.

123. Patient 13-pre implant: Axial CT 3 AxialT2 MRI 3 Axial CT 4 AxialT2 MRI 4 Note the GUD hourglass shape is visible on CT image 4.

124. Axial CT 5 AxialT2 MRI 5 Axial CT 6 AxialT2 MRI 6 Patient 13-pre implant:

125. Axial CT 7 AxialT2 MRI 7 Axial CT 8 AxialT2 MRI 8 Prostate Apex Patient 13-pre implant:

126. Patient 14: Example of round GUD on CT-pre implant Axial CT 1 AxialT2 MRI 1 Axial CT 2 AxialT2 MRI 2 Penile Bulb

127. Axial CT 3 AxialT2 MRI 3 Axial CT 4 AxialT2 MRI 4 Patient 14-pre implant: Note the GUD appears round on the CT and can be mistaken for prostate.

128. Axial CT 5 AxialT2 MRI 5 Axial CT 6 AxialT2 MRI 6 The round diaphragm shape continues into the prostate apex making the GUD/ apex distinction difficult on CT. Patient 14-pre implant:

129. Axial CT 7 AxialT2 MRI 7 Axial CT 8 AxialT2 MRI 8 Patient 14-pre implant:

130. Patient 15: Unclear GUD- pre implant Axial CT 1 AxialT2 MRI 1 Axial CT 2 AxialT2 MRI 2

131. Patient 15-pre implant: Axial CT 3 AxialT2 MRI 3 Axial CT 4 AxialT2 MRI 4 Note that the GUD is not clear on the CT scan making it difficult to determine prostate apex location. On axial CT 4 the elements are barely visible (external sphincter and posterior extension of GUD [white on MRI] ).

132. Axial CT 5 AxialT2 MRI 5 Axial CT 6 AxialT2 MRI 6 At the apex, the CT image is still not clear. Patient 15-pre implant:

133. Axial CT 7 AxialT2 MRI 7 Axial CT 8 AxialT2 MRI 8 Patient 15-pre implant:

134. Patient 16: Example of clear GUD on CT-post implant Axial CT 1 AxialT2 MRI 1 Axial CT 2 AxialT2 MRI 2

135. Axial CT 3 AxialT2 MRI 3 Axial CT 4 AxialT2 MRI 4 Patient 16-post implant: Notice the shape of the GUD and external sphincter is visible on the post implant CT scan as a bull’s eye target (Axial CT3)

136. Axial CT 5 AxialT2 MRI 5 Axial CT 6 AxialT2 MRI 6 Patient 16-post implant:

137. Patient 17: Unclear GUD- post implant Axial CT 1 AxialT2 MRI 1 Axial CT 2 AxialT2 MRI 2

138. Patient 17-post implant: Axial CT 3 AxialT2 MRI 3 Axial CT 4 AxialT2 MRI 4 Note that the GUD is not clear on the CT scan.

139. Axial CT 5 AxialT2 MRI 5 Axial CT 6 AxialT2 MRI 6 The lack of GUD/ prostate apex clarity on CT often results in overestimation of the prostate at the apex. Patient 17-post implant:

140. Axial CT 7 AxialT2 MRI 7 Axial CT 8 AxialT2 MRI 8 Patient 17-post implant:

141. Post-prostate implant T2 MRI scans Part 3: Post Prostate Implant ‘Distortion’ of Anatomy

142. Patient 18: mild post-implant distortion

143. Patient 18- mild distortion Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan PRE POST This patient exhibits only mild-post implant ‘distortion’ of surrounding anatomy. Note the reduced clarity of the prostate border between pre and post scans. However, the GUD and external sphincter remain fairly clear.

144. PRE POST Pre-implant sagittal T2 MRI Scan Pre-implant sagittal T2 MRI Scan Note there is little visible distortion between pre and post sagittal scans of the same patient. Patient 18- mild distortion

145. Axial image 1 Axial image 2 Patient 18: Post-Implant, mild distortion

146. Axial image 3 Axial image 4 Patient 18: Post-Implant, mild distortion

147. Axial image 5 Axial image 6 Patient 18: Post-Implant, mild distortion

148. Axial image 7 Axial image 8 Note the inner (TZ) and outer (PZ) prostate zones are distinct. Patient 18: Post-Implant, mild distortion

149. Axial image 9 Axial image 10 Patient 18: Post-Implant, mild distortion

150. Axial image 11 Patient 18: Post-Implant, mild distortion

151. Patient 19: moderate post-implant distortion

152. Patient 19- moderate distortion PRE POST Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan This patient exhibits moderate post-implant ‘distortion’. Note visible distortion of GUD and external sphincter. Also note the reduced clarity of the prostate border between pre and post scans.

153. Axial image 1 Axial image 2 Patient 19: Post-Implant, moderate distortion

154. Axial image 3 Axial image 4 Patient 19: Post-Implant, moderate distortion

155. Axial image 5 Axial image 6 Note that the mid-prostate margin remains distinct, however, the inner (TZ) and outer (PZ) zones are not distinct. Patient 19: Post-Implant, moderate distortion

156. Axial image 7 Axial image 8 Patient 19: Post-Implant, moderate distortion

157. Axial image 9 Axial image 10 Patient 19: Post-Implant, moderate distortion

158. Axial image 11 Axial image 12 Patient 19: Post-Implant, moderate distortion

159. Axial image 13 Patient 19: Post-Implant, moderate distortion

160. Patient 20: severe post-implant distortion

161. Patient 20-severe distortion PRE POST Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan This patient exhibits severe post-implant ‘distortion’. Note the distortion of both the obturator internus and levator ani muscles post-implant. Possible hemorrhage with superior displacement of prostate

162. PRE POST Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan Note the reduced clarity of the prostate border, as well as the obturator internus and levator ani muscles. Also note the TZ is difficult to define post-implant. Patient 20-severe distortion

163. PRE POST Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan Note the ‘disappearance’ of the prostate apex and the GUD post-implant. Also note the difference in levator ani and obturator internus muscles pre vs post. Patient 20-severe distortion

164. PRE POST Pre-implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan Note the swelling and distortion below the prostate. Patient 20-severe distortion

165. Pre Implant Day of Implant 2 Week Post Implant Pre-implant Coronal T2 MRI Scan Day of implant Coronal T2 MRI Scan Post-implant Coronal T2 MRI Scan Note the penile bulb in the Day of Implant MRI compared to the pre and 2 week post MRIs. Patient 20- Day of MRI

166. Patient 20: Post-Implant, severe distortion Axial image 1 Axial image 2

167. Axial image 1 Axial image 2 Patient 20: Post-Implant, severe distortion

168. Axial image 3 Axial image 4 Patient 20: Post-Implant, severe distortion

169. Axial image 5 Axial image 6 Patient 20: Post-Implant, severe distortion

170. Axial image 7 Axial image 8 Patient 20: Post-Implant, severe distortion

171. Axial image 9 Patient 20: Post-Implant, severe distortion

172. Part 4: Contouring the Prostate on MRI and CT

173. Pre-Implant Scans

174. Patient 21

175. Patient 21 Axial CT without Contour Axial MRI without Contour Penile Bulb Level: inferior to the prostate

176. Axial CT without Contour Axial MRI without Contour Penile Bulb Level: inferior to the prostate Patient 21

177. Patient 21 Axial CT without Contour Axial MRI without Contour Penile Bulb Level: inferior to the prostate

178. Patient 21 Axial CT without Contour Axial MRI without Contour GUD Level: inferior to the prostate - note outline of the GU diaphragm is often visible on CT.

179. Patient 21 Axial CT without Contour Axial MRI without Contour GUD Level: inferior to the prostate - again note the outline of the rectangular GUD is often visible on CT. In this patient the “target” of the external sphincter and urethra is visible as well. At the apex level these distinctions are no longer visible (see following images)

180. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 21 Note lack of boundaries at apex vs. GUD

181. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 21

182. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 21

183. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 21

184. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 21

185. Axial CT without Contour Axial MRI without Contour Patient 21 Seminal Vesicle Level: superior to the prostate

186. Patient 21 Axial CT without Contour Axial MRI without Contour Seminal Vesicle Level: superior to the prostate

187. Patient 22

188. Axial CT without Contour Axial MRI without Contour Patient 22 Penile Bulb Level: inferior to the prostate

189. Axial CT without Contour Axial MRI without Contour Patient 22 GUD Level: inferior to the prostate

190. Axial CT without Contour Axial MRI without Contour Patient 22 GUD Level: inferior to the prostate- in this patient the GUD and external sphincter are not defined on CT.

191. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

192. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

193. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

194. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

195. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

196. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

197. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22 Note the anterior extent of the prostate

198. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

199. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 22

200. Axial CT without Contour Axial MRI without Contour Patient 22

201. Patient 23

202. Axial CT without Contour Axial MRI without Contour Patient 23 Penile Bulb Level: inferior to the prostate

203. Axial CT without Contour Axial MRI without Contour Patient 23 GUD Level: inferior to the prostate

204. Axial CT without Contour Axial MRI without Contour Patient 23 GUD Level: inferior to the prostate

205. Axial CT without Contour Axial MRI without Contour Patient 23 GUD Level: inferior to the prostate

206. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23

207. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23

208. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23

209. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23

210. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23

211. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 23 Prostate Base/ Seminal Vesicle Interface

212. Post Implant Scans

213. Patient 24

214. Axial CT without Contour Axial MRI without Contour Patient 24 Penile Bulb Level: inferior to the prostate

215. Axial CT without Contour Axial MRI without Contour Patient 24 GUD Level: inferior to the prostate

216. Axial CT without Contour Axial MRI without Contour Patient 24 GUD Level: inferior to the prostate

217. Axial CT without Contour Axial MRI without Contour Patient 24 GUD Level: inferior to the prostate

218. Axial CT without Contour Axial MRI without Contour Patient 24 GUD Level: inferior to the prostate

219. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

220. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

221. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

222. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

223. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

224. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

225. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

226. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24

227. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 24 Prostate Base/ Seminal Vesicle Interface

228. Axial CT without Contour Axial MRI without Contour Patient 24

229. Patient 25

230. Axial CT without Contour Axial MRI without Contour Patient 25 Penile Bulb Level: inferior to the prostate

231. Axial CT without Contour Axial MRI without Contour Patient 25 Penile Bulb Level: inferior to the prostate- less distinct post implant on CT

232. Axial CT without Contour Axial MRI without Contour Patient 25 GUD Level: inferior to the prostate

233. Axial CT without Contour Axial MRI without Contour Patient 25 GUD Level: inferior to the prostate

234. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25 The levator ani is often contoured as prostate due to “circling the seeds” Prostate Apex/ GUD Interface

235. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

236. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

237. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

238. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

239. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

240. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

241. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

242. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

243. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

244. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 25

245. Patient 26

246. Axial CT without Contour Axial MRI without Contour Patient 26 Penile Bulb Level: inferior to the prostate

247. Axial CT without Contour Axial MRI without Contour Patient 26 GUD Level: inferior to the prostate

248. Axial CT without Contour Axial MRI without Contour Patient 26 GUD Level: inferior to the prostate

249. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

250. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

251. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

252. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

253. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

254. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

255. Axial CT without Contour Axial CT with Contour Axial MRI without Contour Axial MRI with Contour Patient 26

256. Axial CT without Contour Axial MRI without Contour Patient 26

257. NEUROVASCULAR BUNDLE and CAVERNOSAL NERVES

258. Neurovascular Bundle The neurovascular bundle was so named by Dr. Walsh because the nerves are not grossly visible, but track with the prostatic capsular arteries and veins. These vessels serve as a surgical landmark for the nerves in nerve sparing prostatectomy. The vessels are not visible on time-of-flight angio (see internal pudendal artery section). They are visible on Color Doppler ultrasound but are not visible on CT or MRI. The NVB location can be approximated by a number of methods (1,2). In the superior prostate/ seminal vesicle region they pass from the lateral seminal vesicle to the junction of the prostate and rectum. In the inferior prostate they course within the triangle formed by the rectum, prostate and levator ani.

259. Lateral Pelvic Fascia Levator Fascia Prostate Fascia Denonvillieres’ Fascia Prostate Capsule Rectum Prostate Neurovascular Bundle (Schematic) : The neurovascular bundle is located between the two layers of the lateral pelvic fascia (levator fascia and prostate fascia) near the junction with Denonvillieres’ fascia. Neurovascular Bundle (NVB) NVB

260. Cavernosal Nerves The terminal branches of the NVB are the cavernosal nerves. The greater cavernosal nerve was defined in Gray’s anatomy as a terminal branch of the NVB which coursed anterior along the GU diaphragm and through the fault in the anterior GUD through which the dorsal venous complex passes. Though described as greater due to its clarity relative to the lesser cavernosal nerve, there are no references to the greater cavernosal nerve in the modern surgical / anatomic literature . The lesser cavernosal nerve passes through the GUD in a fixed relationship to the external sphincter. In the supine position: At the apex the nerves are located in the 7 and 5 o’clock position. In mid GUD they are located at 9 and 3 o’clock. In the inferior GUD, just above the Corpus Cavernosa, they are positioned at 11 and 1 o’clock.

261. Patient 1: Axial T2 MRI

262. Patient 1, Axial T2 MRI NVB NVB Prostate Bladder

263. Patient 1, Axial T2 MRI NVB NVB Prostate Bladder

264. Patient 1, Axial T2 MRI NVB NVB Prostate Bladder

265. Patient 1, Axial T2 MRI NVB NVB Prostate Rectum

266. Patient 1, Axial T2 MRI NVB NVB Prostate Rectum

267. Patient 1, Axial T2 MRI NVB NVB Prostate Rectum

268. Patient 1, Axial T2 MRI NVB NVB Prostate Rectum

269. Patient 1, Axial T2 MRI NVB NVB Prostate

270. Patient 1, Axial T2 MRI Neurovascular bundle (NVB) Neurovascular bundle (NVB) area alongside Prostate that would contain the Greater Cavernosal Nerves area alongside Prostate that would contain the Greater Cavernosal Nerves

271. Patient 1, Axial T2 MRI Level : Prostate Apex The lesser cavernosal nerves are not visible radiographically. At the prostate apex they are located nerves at the 7 and 5’o’clock position. Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter Prostate Apex

272. Patient 1, Axial T2 MRI Level : GUD Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter GUD

273. Patient 1, Axial T2 MRI Level : mid-GUD At the mid GUD they are located at the 9 and 3 o’clock position Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter GUD

274. Patient 1, Axial T2 MRI Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter

275. Patient 1, Axial T2 MRI At the mid-to-inferior GUD they transition towards the 11 and 1’o’clock positions. Lesser Cavernosal Nerve Lesser Cavernosal Nerve Rectum

276. Patient 1, Axial T2 MRI Level : 1 cut above penile bulb At the inferior GUD they appear at the 11 and 1’o’clock position. Lesser Cavernosal Nerve Lesser Cavernosal Nerve

277. Patient 2, Axial T2 MRI Patient Prone

278. Image 7 Image 8 Rectum Neurovascular bundle (NVB) Patient 2, Axial T2 MRI Neurovascular bundle (NVB) Prostate beg. of Bladder

279. Patient 2, Axial T2 MRI NVB NVB Prostate Rectum

280. Patient 2, Axial T2 MRI NVB NVB Prostate Rectum

281. Patient 2, Axial T2 MRI NVB NVB Prostate Rectum

282. Patient 2, Axial T2 MRI Neurovascular bundle (NVB) Neurovascular bundle (NVB) Prostate

283. Neurovascular bundle (NVB) Neurovascular bundle (NVB) Patient 2, Axial T2 MRI area alongside Prostate that would contain the Greater Cavernosal Nerves area alongside Prostate that would contain the Greater Cavernosal Nerves

284. Patient 2, Axial T2 MRI The lesser cavernosal nerves appear at the apex. Note that they seem localized at the 11 and 1’o’clock relative to the prostate because the patient is prone. If supine, it would be noted at the 5 and 7 o’clock position. Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter Prostate Apex Level: Apex

285. Patient 2, Axial T2 MRI Here they appear at the 9 and 3’o’clock positions. Lesser Cavernosal Nerve Lesser Cavernosal Nerve Rectum External Sphincter Level: mid-GUD

286. Image 7 Image 8 Rectum External Sphincter Lesser cavernosal nerve Patient 2, Axial T2 MRI

287. Image 7 Image 8 GUD Rectum External Sphincter Lesser Cavernosal Nerve Patient 2, Axial T2 MRI Lesser Cavernosal Nerve

288. Patient 2, Axial T2 MRI Lesser Cavernosal Nerves At the inferior GUD the nerves are at 5 and 7 o’clok in the prone patient

289. Patient 3, Axial T2 MRI Patient Supine

290. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

291. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

292. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

293. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

294. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

295. Patient 3, Axial T2 MRI NVB NVB Prostate Rectum

296. Patient 3, Axial T2 MRI Neurovascular bundle (NVB) Neurovascular bundle (NVB) area alongside Prostate that would contain the Greater Cavernosal Nerves area alongside Prostate that would contain the Greater Cavernosal Nerves

297. Patient 3, Axial T2 MRI Transition from NVB to cavernosal nerves just above the prostate apex NVB/Lesser Cavernosal Nerve NVB/Lesser Cavernosal Nerve

298. Patient 3, Axial T2 MRI Level : mid-GUD At mid GUD they appear at the 9 and 3’o’clock positions. Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter GUD

299. Patient 3, Axial T2 MRI At the inferior GUD they appear at the 11 and 1’o’clock position. Level : GUD Lesser Cavernosal Nerve Lesser Cavernosal Nerve External Sphincter GUD

300. References G.S. Merrick, W.M. Butler et al. , A comparison of radiation dose to the neurovascular bundles in men with and without prostate brachytherapy-induced erectile dysfunction. Int J Radiat Oncol Biol Phys 48 (2000), pp.1069-1074. 2. S.J. DiBiase, K. Wallner et al. , Brachytherapy radiation doses to the neurovascular bundles. Int J Radiat Oncol Biol Phys 46 (2000), pp. 1301-1307.

301. PUDENDAL CANAL and INTERNAL PUDENDAL ARTERY

302. The internal pudendal artery is a branch of the internal iliac artery. It passes along the lateral pelvic wall and through the pudendal canal. The pudendal canal is a connective tissue sheath on the medial surface of the Obturator internus. It then passes through the inferior fascia of the genitourinary diaphragm (GUD). Its terminal branches are within the GUD and supply penile bulb and corpus cavernosa. Internal Pudendal Artery

303. Patient 1: Axial T2 MRI

304. Patient 1, Axial MRI Note the two circled structures as they make their way around the ischium and up towards the crura in the following images. IPA IPA Prostate Bladder Obturator internus Obturator internus Ischium Bone Ischium Bone

305. Patient 1, Axial MRI IPA IPA Bladder

306. Patient 1, Axial MRI IPA IPA Obturator internus Rectum

307. Patient 1, Axial MRI IPA IPA Ischioanal/ Ischiorectal Fossa (IF)

308. Patient 1, Axial MRI IPA IPA Obturator internus

309. Patient 1, Axial MRI IPA IPA

310. Patient 1, Axial MRI IPA IPA

311. Patient 1, Axial MRI IPA IPA

312. Patient 1, Axial MRI IPA IPA

313. Patient 1, Axial MRI IPA IPA

314. Patient 1, Axial MRI IPA IPA External Sphincter Prostate Apex

315. Patient 1, Axial MRI IPA IPA Prostate Apex External Sphincter Rectum

316. Patient 1, Axial MRI IPA IPA External Sphincter GUD Rectum

317. Patient 1, Axial MRI IPA IPA GUD External Sphincter IF Levator ani

318. Patient 1, Axial MRI IPA IPA

319. IPA IPA Penile Bulb Patient 1, Axial MRI After entering the GUD the IPA into branches to supply the penile bulb and corpus cavernosum

320. Patient 2: Axial T2 MRI

321. Patient 2, Axial MRI IPA Ischium Prostate Rectum Bladder

322. Patient 2, Axial MRI IPA Prostate Obturator internus

323. Patient 2, Axial MRI IPA IPA

324. Patient 2, Axial MRI IPA IPA

325. Patient 2, Axial MRI IPA IPA

326. Patient 2, Axial MRI IPA IPA

327. Patient 2, Axial MRI IPA IPA

328. Patient 2, Axial MRI IPA IPA External Sphincter Prostate Apex

329. Patient 2, Axial MRI IPA IPA Prostate Apex

330. Patient 2, Axial MRI IPA IPA External Sphincter Rectum

331. Patient 2, Axial MRI IPA IPA

332. Patient 2, Axial MRI IPA IPA Rectum Crura of Corpus Cavernosa

333. Patient 3: Axial T2 MRI

334. Patient 3, Axial T2 MRI IPA IPA Prostate Rectum Obturator internus

335. Patient 3, Axial T2 MRI IPA IPA

336. Patient 3, Axial T2 MRI IPA IPA Prostate Apex

337. Patient 3, Axial T2 MRI IPA IPA IF GUD External Sphincter

338. Patient 3, Axial T2 MRI IPA IPA

339. Patient 3, Axial T2 MRI The Ischioanal/Ischiorectal Fossa (IF) are the wedge-shaped areas lateral to the anal canal. The pudendal canal is found on the lateral wall of the IF. Ischioanal Fossa (IAF) Rectum IPA IPA

340. Patient 3, Axial T2 MRI IPA IPA

341. Patient 3, Axial T2 MRI IPA IPA Corpus Cavernosa

342. Patient 3, Axial T2 MRI IPA IPA Corpus Cavernosum Corpus Cavernosum Penile Bulb

343. Patient 4: Axial CT and T2 MRI The following images are a side by side comparison of a patient CT and correlating Axial T2 MRI. In a subset of patients it is possible to localize the IPA on CT but it is more obvious on MRI.

344. Patient 4, CT vs. Axial T2 MRI Post Implant IPA IPA IPA IPA

345. Patient 4, CT vs. Axial T2 MRI Patient 4, CT vs Axial T2 MRI IPA IPA IPA IPA

346. Patient 4, CT vs. Axial T2 MRI IPA IPA IPA IPA

347. Locating Pudendal Arteries on Coronal MRI The terminal branches of the IPA within the GUD are poorly visualized on Axial MRI. They can be identified on Coronal MRI as a cluster of vessels above the corpus cavernosa. These vessels can be traced posterior to the pudendal canal which is well visualized on coronal view.

348. Patient 5: Coronal T2 MRI

349. Patient 5, Coronal T2 MRI IPA IPA in the pudendal canal IF

350. Patient 5, Coronal T2 MRI IPA IPA

351. Patient 5, Coronal T2 MRI IPA IPA

352. Patient 5, Coronal T2 MRI IPA IPA Levator ani Levator ani

353. Patient 5, Coronal T2 MRI IPA IPA Obturator internus

354. Patient 5, Coronal T2 MRI IPA IPA Obturator internus

355. Patient 5, Coronal T2 MRI Terminal branches of IPA = Terminal IPA Crura of Corpus Cavernosum Terminal branches of IPA

356. Patient 5, Coronal T2 MRI Terminal IPA Terminal IPA Penile Bulb Prostate Crura of Corpus Cavernosum

357. Patient 6: Coronal T2 MRI

358. Patient 6, Coronal T2 MRI IPA IPA Rectum

359. Patient 6, Coronal T2 MRI IPA IPA

360. Patient 6, Coronal T2 MRI IPA IPA

361. Patient 6, Coronal T2 MRI IPA IPA

362. Patient 6, Coronal T2 MRI IPA IPA

363. Patient 6, Coronal T2 MRI IPA IPA

364. Patient 6, Coronal T2 MRI IPA IPA

365. Patient 6, Coronal T2 MRI IPA IPA Bladder

366. Patient 6, Coronal T2 MRI IPA IPA

367. Patient 6, Coronal T2 MRI IPA IPA

368. Patient 6, Coronal T2 MRI IPA IPA in pudendal canal Levator Ani Obturator internus

369. Patient 6, Coronal T2 MRI IPA IPA Prostate beginning of crura

370. Patient 7, Coronal T2 MRI

371. Patient 7, Coronal T2 MRI IPA IPA

372. Patient 7, Coronal T2 MRI IPA IPA

373. Patient 7, Coronal T2 MRI IPA Bladder IPA

374. Patient 7, Coronal T2 MRI Terminal IPA Terminal IPA Bladder

375. Patient 7, Coronal T2 MRI Terminal IPA Terminal IPA Bladder

376. Patient 7, Coronal T2 MRI Terminal IPA Terminal IPA Prostate Bladder Penile Bulb

377. Patient 7, Coronal T2 MRI Terminal IPA Terminal IPA Bladder Penile Bulb

378. Patient 7, Coronal T2 MRI Terminal IPA Terminal IPA Bladder Corpus cavernosum

379. Patient 7, Coronal T2 MRI Terminal branches of IPA Terminal branches of IPA Bladder Penile Bulb Corpus Cavernosum External Sphincter

380. Angio vs. Axial MRI This image shows the fusion of the Angio MRI to its correlating Axial T2 MRI. Note the IPA is visible on both scans. IPA IPA Prostate

381. Pudendal Arteries on Angiogram The following angiograms were obtained by a time of flight MRI sequence, a non contrast study completed in less than 10 minutes. There is great variation in the quality of an IPA time of flight angiogram. The range from poor to excellent visualization may be due to differences in body habitus, technical factors and vessel patency. The following images clearly display the course of the IPA.

382. Patient 8: IPA Angiogram

383. Patient 8, Angio MRI IPA IPA

384. Patient 8, Angio MRI IPA IPA Prostate Obturator internus

385. Patient 8, Angio MRI IPA IPA

386. Patient 8, Angio MRI IPA IPA Prostate

387. Patient 8, Angio MRI IPA IPA

388. Patient 8, Angio MRI IPA IPA

389. Patient 8, Angio MRI IPA IPA IF

390. Patient 8, Angio MRI IPA IPA

391. Patient 8, Angio MRI IPA IPA

392. Patient 8, Angio MRI IPA IPA

393. Patient 8, Angio MRI IPA IPA

394. Patient 8, Angio MRI IPA IPA

395. Patient 8, Angio MRI IPA IPA

396. Patient 8, Angio MRI Rectum IPA IPA

397. Patient 9: IPA Angiogram (Patient Prone)

398. Patient 9, Angio MRI IPA Prostate IPA Rectum Pubic Symphysis Femoral Head

399. Patient 9, Angio MRI IPA IPA Prostate

400. Patient 9, Angio MRI IPA IPA Rectum Prostate

401. Patient 9, Angio MRI IPA IPA

402. Patient 9, Angio MRI IPA IPA IF IF Rectum Prostate

403. Patient 9, Angio MRI IPA IPA

404. Patient 9, Angio MRI IPA IPA

405. Patient 9, Angio MRI IPA IPA

406. Patient 9, Angio MRI IPA IPA

407. Patient 9, Angio MRI IPA IPA

408. Patient 9, Angio MRI IPA IPA

409. Patient 9, Angio MRI IPA IPA

410. Patient 9, Angio MRI IPA IPA

411. Patient 9, Angio MRI IPA IPA

412. Patient 9, Angio MRI IPA IPA

413. Patient 9, Angio MRI IPA IPA

414. Patient 9, Angio MRI IPA IPA

415. Patient 9, Angio MRI IPA IPA

416. Patient 9, Angio MRI IPA IPA

417. Patient 9, Angio MRI IPA IPA

418. Patient 9, Angio MRI IPA IPA

419. Patient 9, Angio MRI IPA IPA Penile Bulb

420. Angio MRI vs. CT The following images are side by side comparisons of IPA visible on Angio MRI and the equivalent CT. Since it is difficult to locate the IPA on CT, the contours shown on CT are cut from the correlated Angio MRI images.

421. Patient 10, Angio MRI IPA IPA Prostate Rectum Rectum

422. Patient 10, Angio MRI IPA IPA

423. Patient 10, Angio MRI IPA IPA

424. Patient 10, Angio MRI IPA IPA

425. Patient 10, Angio MRI IPA IPA Note that the IPA is slightly visible on CT. Its location is relative to the IPA identified in the Angio.

426. Angio MRI vs. CT The following images on CT show the visible and estimated position of the the IPA based on its relationship to adjacent structures. They have not been contoured but rather encircled broadly to allow review of the vessel appearance and location on CT. Calcification of the vessels may improve visualization on CT.

427. Patient 10, Angio MRI IPA IPA

428. Patient 10, Angio MRI IPA IPA

429. Patient 10, Angio MRI IPA IPA

430. Patient 10, Angio MRI IPA IPA

431. Patient 10, Angio MRI IPA IPA

432. A 3D Image of Prostate and critical adjacent structures