ultrasonography in urology surgery.pptx

usg in urology

1. URINARY TRACT IMAGING Presented by Dr. Rohit K. Gupta

2. Basic Principles of Urologic Ultrasonography Ultrasound has often been referred to as the urologist's stethoscope. Ultrasonography is a versatile and relatively inexpensive imaging modality that has the unique feature of being the only imaging modality to provide real-time evaluation of urologic organs and structures without the need for ionizing radiation.

3. History of USG In 1880, Pierre and Jacques Curie made an important discovery that eventually led to the development of the modern-day ultrasound transducer. The Curie brothers observed that when pressure was applied to crystals of quartz or Rochelle salt, an electric charge was generated. This charge was directly proportional to the force applied to it, and the phenomenon was called “piezoelectricity” from the Greek word meaning “to press .”

4. Brief History of Ultrasound in Urology 1963 - Japanese urologists Takahashi and Ouchi became the first to attempt ultrasonic examination of the prostate. 1955 -Wild and Reid – transrectal ultrasonography 1974 -Watanabe et al. demonstrated radial scanning that could adequately identify prostate and bladder pathology “Magician's Chair,” Watanabe seated his patients on a chair with a hole cut in the center such that the transducer tube could be passed through the hole and into the rectum of the seated patient)

5. 1971 Goldberg and Pollack-A mode nephrosonography -in a series of 150 patients the capability of ultrasound to discern solid, cystic, and complex masses with an accuracy of 96 %. 2010 -Chen et al. used transrectal ultrasound guidance to inject botulinum toxin into the external urethral sphincters of a series of patients with detrusor external sphincter dyssynergia

6. A rea of circumscribed symmetric echogenicity representing benign prostatic hyperplasia [BPH]) and 4.1C (demonstrating an asymmetric area of hyperechogenicity , representing prostate cancer

7. Goldberg and Pollack were the first to differentiate among solid, complex, and cystic masses by ultrasound. In cystic lesions, the first spike represents the striking of the front wall of the cyst, and the second spike represents the striking of the back wall. More complex lesions therefore have return of more spikes. (From Goldberg B, Pollack H: Differentiation of renal masses using A-mode ultrasound. J Urol 167[2]:1022–1026, 2002.)

8. 1976 - Perri et al. were the first to use Doppler as a sonic “stethoscope” in their workup of patients with an acute scrotum. 1981 -Greene et al. documented that Doppler could adequately differentiate stenotic from normal renal arteries 1982 - Arima et al. used Doppler to differentiate acute from chronic rejection in renal transplant patients

9. PHYSICAL PRINCIPLES Ultrasound Image Generation Resolution Mechanisms of Attenuation Artifacts

10. Physical Principles Ultrasound imaging is the result of the interaction of sound waves with tissues and structures Ultrasound waves are produced by applying short bursts of alternating electrical current to a series of crystals housed in the transducer Alternating expansion and contraction of the crystals via the piezoelectric effect creates a mechanical wave that is transmitted through a coupling medium to the skin and then into the body

11. Physical Principles Cont.. The waves that are produced are longitudinal waves This motion produces areas of rarefaction and compression of tissue in the direction of travel of the ultrasound wave A portion of the wave is reflected toward the transducer, and it serves as a receiver and “listens” for the returning sound wave reconverting the mechanical to electrical energy.

12. The alternating expansion and contraction of the crystal produces longitudinal mechanical waves. In this simplified schematic drawing, the individual molecules (depicted as circles) are displaced in the direction of the propagated wave.

13. Areas of compression alternating with areas of rarefaction are depicted as a sine wave. The wavelength (λ) is the length from peak compression to peak compression in this drawing. This graphic depiction is critical to the understanding of the behavior of sound waves in the human body and of how ultrasound images are generated. (From Merritt CRB: Physics of ultrasound. In Rumack C, Wilson S, eds : Diagnostic ultrasound, ed 3, St. Louis, 2005, Elsevier.)

14. Physical Principles Cont.. The appearance of the image produced by ultrasonography is the result of the interaction of mechanical ultrasound waves with biologic tissues and materials. Ultrasound waves are transmitted and received at frequent intervals, the images can be rapidly reconstructed and refreshed, providing a real-time image. The frequencies of the sound waves used for urologic ultrasound imaging are in the range of 3.5 to 20 MHz

15. ULTRASOUND IMAGE GENERATION The image produced by an ultrasound machine begins with the transducer the transducer has a dual function as a sender and receiver Sound waves are created in short pulses and transmitted into the body and are then at least partially reflected Reflected mechanical sound waves are received by the transducer and converted back into electrical energy. The transducer acts as a receiver more than 99% of the time.

16. In this simplified schematic diagram of ultrasound imaging, the ultrasound wave is produced by a pulse generator controlled by a master clock. The reflected waves received by the transducer are analyzed for amplitude and transit time within the body. The scan converter produces the familiar picture seen on the monitor. The actual image is a series of vertical lines that are continuously refreshed to produce the familiar realtime , gray-scale image.

17. RESOLUTION The resolution of an ultrasound image refers to the ability to discriminate between two objects that are close to one another. Axial resolution refers to the ability to identify as separate two objects in the direction of the traveling sound wave. Lateral resolution refers to the ability to identify separately objects that are equidistant from the transducer

18. The velocity with which a sound wave travels through tissue is a product of its frequency and wavelength The average velocity of sound in human tissues is 1540 meters per second. High-frequency transducers of 7 to 18 MHz may be used to image structures near the surface of the body (e.g., testis, pediatric kidney) with excellent resolution

19. Mechanisms of Attenuation As sound waves transit tissues, energy is lost or attenuated Mechanisms of attenuation include reflection, scattering, interference, and absorption Reflection is the key physical phenomenon that allows for information to return to the transducer as mechanical energy . Impedance is a property that is influenced by tissue stiffness and density. The amount of energy reflected from an interface is also influenced by the impedance of the two tissues at the interface

20. Density and Impedance of Tissue Encountered During Urologic Ultrasound DENSITY (kg/m3) IMPEDANCE (kg/m2s) Air and other gases 1.2 0.0004 Fat tissue 952 1.38 Water and other clear liquids 1000 1.48 Kidney (average of soft tissue) 1060 1.63 Liver 1060 1.64 Muscle 1080 1.70 Bone and other calcified objects 1912 7.80

21. The impedance difference between perinephric fat and the kidney allows a sharp visual distinction at the interface. If the impedance difference between tissues is small (such as that between the liver and kidney), the interface between the tissues will be more difficult to see. If impedance differences are large, there will be significant reflection of the sound wave producing an acoustical shadow distal to the interface

22. (A) In this sagittal view of the right kidney, the paucity of perinephric fat and the small impedance difference make it difficult to distinguish the interface between the kidney and the liver (arrows). (B) The large impedance difference at the interface between urine and this bladder stone (arrow) results in significant reflection and attenuation of the sound wave. An acoustic shadow is seen distal to the stone (arrowheads).

23. Absorption occurs when the mechanical energy of the ultrasound waves is converted to heat Absorption is directly proportional to frequency

24. ARTIFACTS The interaction of ultrasound waves with tissues may produce images that do not reflect the true underlying anatomy These misrepresentations are called “artifacts.” Artifacts may be misleading but, if recognized, may also assist in diagnosis Acoustic shadowing occurs when there is significant attenuation or reflection of sound waves at a tissue interface

25. In this transverse view of the urinary bladder (B), there are two large bladder diverticula (D). Two stones (arrows) strongly reflect and attenuate the incident sound wave, producing an acoustic shadow. Note that the stones appear crescentic even though they are ovoid.

26. Modes of Ultrasound Gray-Scale Ultrasound Doppler Ultrasound Harmonic Scanning Spatial Compounding Sonoelastography Three-Dimensional Scanning Multiparametric Ultrasound

27. Gray-Scale Ultrasound/B-MODE The most commonly employed mode of ultrasound real-time two-dimensional (2D) images consisting of shades of gray Variations from these expected patterns of echogenicity indicate disorders of anatomy or physiology

28. Doppler Ultrasound depends on the physical principle of frequency shift when sound waves strike a moving object The basic principle of Doppler ultrasound is that sound waves of a certain frequency will be shifted or changed on the basis of the direction and velocity of the moving object as well as the angle of insonation A color map may be applied to direction with the most common assignation of the color blue to motion away from the transducer and red to motion toward the transducer

29. Color Doppler may be used to evaluate the presence or absence of blood flow in the kidney, testes, penis, and prostate It also may be useful in the detection of ureteral “jets” of urine emerging from the ureteral orifices.

30. Harmonic Scanning related to the nonlinear propagation of sound waves within tissue these harmonics are not subject to scattering at the frequency associated with the incident wave, there is less noise associated with the signal. Concentrating on the harmonic frequencies produced within the body and reflected to the transducer allows production of an image with less artifact and greater resolution.

31. (A) Standard gray-scale image of a cyst containing a mural nodule (arrowhead). Note the artifactual echogenicity within the cyst (arrow). (B) The same structure on harmonic scanning is more clearly seen. There is less artifact within and distal to the cyst. (From Merritt CRB: Physics of ultrasound. In Wilson S, Rumack C, eds : Diagnostic ultrasound, ed 3, St. Louis, 2005, Elsevier.)

32. Spatial Compounding Spatial compounding is a scanning mode whereby the direction of insonation is electronically altered and a composite image is generated This technique reduces the amount of artifact and noise, producing a scan of better clarity

33. Sonoelastography Sonoelastography (tissue elasticity imaging) is an ultrasound modality that adds the ability to evaluate the elasticity (compressibility and displacement) of biologic tissues Essentially, it gives a representation, using color, of the softness or hardness of the tissue of interest Presently, there are two ways to produce this mechanical wave: real-time elastography (RTE) and shear wave elastography (SWE).

34. In RTE, as in standard diagnostic, an external, nonquantifiable mechanically produced compression wave travels in tissue (1540 m/s). These waves successively compress tissue layers, producing backscattered reflected waves that are received and processed by the ultrasound equipment producing an image

35. Real-time elastography . A 4-mm hypoechoic nodule (arrowhead, left panel) was found with Doppler ultrasound with vascular flow internally. Real-time sonoelastography suggested a hard nodule (with this equipment blue is hard, not soft). Close follow-up with ultrasound every 3 months found no increase in size of the nodule. It was therefore considered “probably” benign. (From Goddi A et al: Real-time tissue elastography for testicular lesion assessment. Eur Radiol 22[4]:721–730, 2012.)

36. In SWE the shear wave produced can be measured precisely and travels more slowly (1 to 10 m/s). With SWE low-frequency (~100-Hz) pulses are rapidly transmitted into the tissue to induce a vibration in the tissue.

37. Shear wave elastography . (A) Two small hypoechoic vascular lesion (arrows, lower panel) found with B-mode ultrasound is shown in the upper panel to be a soft (blue) lesion with shear wave elastography ultrasound. Biopsy confirmed a Sertoli cell nodule. (B) A larger lesion with heterogeneous echogenicity on B-mode ultrasound (lower panel) demonstrates diffuse “hardness” on shear wave elastography (upper panel). Pathology demonstrated a nonseminomatous germ cell tumor.

38. Three-Dimensional Scanning Three-dimensional (3D) scanning has been used extensively in obstetrics and gynecology but so far has limited application in urology 3D scanning produces a composite of images which can then be manipulated to generate additional views of the anatomy.

39. A three-dimensional image of the testis demonstrating intratesticular blood flow on power Doppler. The image can be virtually rotated and manipulated to produce unique anatomic perspectives. (Used with permission by BK Medical.)

40. Multiparametric Ultrasound Just as multiparametric MRI ( mpMRI ) offers excellent anatomic resolution with T2- weighted imaging, ultrastructural histology with water diffusion, and vascularity with contrast enhancement, mpUS is able to address all of those tissue properties in real time mpUS is already used in transrectal ultrasound of the prostate and is finding many applications in nonprostate ultrasoundS

41. Multiparametric ultrasound is compared with MRI. ADC, Apparent diffusion coefficient; SNF, systemic nephrogenic fibrosis.

42. Contrast Agents in Ultrasound Intravenous compounds that contain microbubbles have been used for enhancing the echogenicity of blood and tissue Contrast agents may be useful in prostatic ultrasonography by enhancing the ability to recognize areas of increased vasculature Several intravenous ultrasound contrast agents have been approved by the US Food and Drug Administration (FDA) They have a good safety profile and have found use in a number of urologic scanning situations (Auer et al., 2017; Mitterberger et al., 2007a; Wildeboer et al., 2017; Wink et al., 2008).

43. Images By convention, the liver is used as a benchmark for echogenicity . If a structure is hypoechoic , it means it is darker than the surrounding tissues. If a structure is hypoechoic , it means it is darker than the surrounding tissues If it is hyperechoic , it means it is brighter than the surrounding tissues. Isoechoic means it is similar to the surrounding tissues Structures that do not generate echoes are called anechoic. A simple cyst is an example of a structure with an anechoic interior.

44. In general, a high water content causes tissue to appear hypoechoic . In general, a high fat content causes tissue to appear hyperechoic

45. Clinical Urologic Ultrasound Renal Ultrasound Transabdominal Pelvic Ultrasound Ultrasonography of the Scrotum Ultrasonography of the Penis and Male Urethra Transrectal Ultrasonography of the Prostate

46. Renal Ultrasound Urologists, because of their intimate knowledge of surgical anatomy of the kidneys and retroperitoneum , are uniquely qualified to perform and interpret selected ultrasound examinations of the abdomen Urologists generally perform abdominal ultrasonography for a specific clinical indication and less often for general screening of the abdominal contents.

47. Technique- Renal Ultrasound The transducer normally used for renal ultrasonography is a curved array transducer of 3.5 to 5.0 MHz Transducers of a higher frequency may be used for pediatric patients Scanning of the right kidney is performed with the patient supine The kidney is located by beginning in the midclavicular line in the right upper quadrant. In the sagittal plane the transducer is moved laterally until the midsagittal plane of the kidney is imaged

48. Once the kidney has been imaged anteriorly and posteriorly in the sagittal plane, the probe is rotated 90 degrees counterclockwise. The midtransverse plane will demonstrate the renal hilum containing the renal vein. The kidney is scanned from the upper pole to the lower pole. The technique and documentation for left renal ultrasonography is identical to that of the right side

49. Indications-Renal Ultrasound 1. Assessment of renal and perirenal masses 2. Assessment of the dilated upper urinary tract 3. Assessment of flank pain during pregnancy 4. Evaluation of hematuria in patients who are not candidates for IVP, CT, or MRI because of renal insufficiency, contrast allergy, or physical impediment 5. Assessment of the effects of voiding on the upper urinary tract 6. Evaluation for and monitoring of urolithiasis 7. Intraoperative renal parenchyma and vascular imaging for ablation of renal masses 8. Percutaneous access to the renal collecting system 9. Guidance for transcutaneous renal biopsies, cyst aspiration, or ablation of renal masses 10. Postoperative evaluation of patients after renal and ureteral surgery 11. Postoperative evaluation of renal transplant patients

50. Normal Findings The lower pole of the kidney is displaced 15 degrees laterally compared with the upper pole (A). The kidney is rotated 30 degrees posterior to the true coronal plane (B). The lower pole of the kidney is slightly anterior compared with the upper pole.

51. - The adult right kidney in the sagittal view demonstrates a cortex that is usually hypoechoic with respect to the liver - The central band of echoes in the kidney is a hyperechoic area that contains the renal hilar adipose tissue, blood vessels, and collecting system -By having the patient take a deep breath, the kidney can be moved inferiorly to assist complete imaging

52. The echogenicity of the kidney varies with age. The renal cortex of an infant is relatively hyperechoic compared with that of an adult. In the adult, the echogenicity of the renal cortex is usually hypoechoic with respect to the liver ( Emamian et al., 2013) In patients with chronic medical renal diseases the renal cortex is often thinned and isoechoic or hyperechoic with respect to the liver (O'Neill, 2001).

53. The average adult kidney measures 10 to 12 cm in length and 4 to 5 cm in width. Measurements of renal volume may be appropriate in cases of severe renal impairment Although there is no universal standard, the renal cortical thickness should be greater than 7 mm and the renal parenchymal thickness should be greater than 15 mm in adults ( Emamian et al., 2013).

54. The distinction between renal cortical thickness and renal parenchymal thickness is that the renal parenchyma is measured from the central band of echoes to the renal capsule. The renal cortex is measured from the outer margin of the medullary pyramid to the renal capsule

55. Doppler ultrasound may be helpful in evaluating the renal artery and renal vein and assessing the vascular resistance in the kidney Doppler modes may also be useful in evaluating neovascularity associated with renal tumors and in correctly characterizing hypoechoic structures in the renal pelvis such as a parapelvic cyst, the renal vein, or the dilated collecting system

56. Procedural Applications Percutaneous renal biopsy as an office procedure has been used by several groups for the past two decades and found to be a safe and effective procedure (Christensen et al., 1995; Fraser and Fairley, 1995; Hergesell , 1998)

57. Limitations Some patients are not favorable candidates for renal ultrasonography . Obesity, intestinal gas, and physical deformity may be impediments to complete renal evaluation Renal ultrasonography has poor sensitivity for renal masses less than 2 cm ( Warshauer , McCarthy, and Street, 1988) There is a lack of specificity for renal tumor type except for angiomyolipoma . Angiomyolipoma has characteristics that are distinctive on ultrasonography (highly echoic), but some small renal cell carcinomas have been shown to be indistinguishable from angiomyolipoma by ultrasound criteria (Forman, Middleton, and Melson , 1993;Yamashita, Takahashi, and Watanabe, 1992).

58. Transabdominal Pelvic Ultrasound Transabdominal pelvic ultrasonography is a tremendously versatile tool for the urologist It is a noninvasive method for evaluating the lower urinary tract and prostate in men and the bladder in women A curved array transducer of 3.5 to 5 MHz is most commonly employed to perform transabdominal ultrasonography

59. Technique Bladder ultrasonography is most commonly performed with the patient supine and the sonographer on the patient's right side. The scan should be performed in a warm room and the patient draped to provide for comfort and privacy generalLY should be performed with a moderately full bladder transabdominal scanning is the most common means of evaluating the bladder, The bladder may also be assessed via a transvaginal and transrectal approach. These approaches are useful in patients who are obese or who are not suitable candidates for transabdominal scanning.

60. Indications 1. Measurement of bladder volume or postvoid residual urine 2. Assessment of prostate size and morphology 3. Demonstration of secondary signs of bladder outlet obstruction 4. Evaluation of bladder wall configuration and thickness 5. Evaluation of hematuria of lower urinary tract origin 6. Detection of ureteroceles 7. Assessment for ureteral obstruction 8. Detection of perivesical fluid collections 9. Evaluation of clot retention 10 . Confirmation of catheter position 11. Removal of retained catheter 12. Guidance of suprapubic tube placement 13. Establishment of bladder volume before and after flow rate determination

61. Normal Findings Transabdominal pelvic ultrasonography should include evaluation of the lumen of the bladder, as well as bladder wall configuration and thickness. The presence of specific lesions such as stones or tumors should be documented. The structures immediately surrounding the bladder may also be evaluated including the distal ureters , the prostate in men, and the uterus and ovaries in women The emergence of urine from the ureteral orifices ( ureteral jets) can be demonstrated. The clinical value of demonstrating ureteral jets has been questioned. Up to 10 minutes of continuous observation may be required to verify the absence of a ureteral jet ( Delair and Kurzrock , 2006).

62. (A) Transverse view of the bladder (BL) in this female patient demonstrates the uterus (U). (B) Sagittal view of the bladder shows the uterus posterior to the bladder

63. In this transverse view of the bladder, ureteral “jets” emerging from the left (arrow) and right (arrowhead) ureteral orifices are demonstrated by power Doppler.

64. Bladder volume can be calculated manually by obtaining measurements in the midtransverse and midsagittal planes. Numerous studies have shown that for bladder volumes between 100 and 500 mL , such calculated volumes are within 10% to 20% of the actual bladder volume Measuring bladder wall thickness may assist the clinician in understanding the degree of bladder outlet obstruction It has been shown that measuring bladder wall thickness may predict bladder outlet obstruction with greater accuracy than free uroflowmetry , postvoid residual urine, and prostate volume ( Oelke et al., 2007).

65. Measurement of bladder volume using this formula: bladder volume = width (transverse plane) × height (transverse plane) × length ( midsagittal plane) × 0.625. In the sagittal plane, the dome (D) of the bladder is to the left and the prostate (P) to the right.

66. Bladder wall thickness may provide information about bladder outlet obstruction. In this sagittal view, bladder wall thickness is measured posteriorly (arrow) near the midline. Note the trabeculation of the relatively hyperechoic bladder wall.

67. Transabdominal prostatic ultrasonography requires angling the probe beneath the pubic bone In the transverse plane the transducer is fanned inferiorly until the largest transverse diameter of the prostate is identified The transducer is then rotated 90 degrees clockwise to produce a true sagittal image of the prostate. The transducer is fanned until the midline is identified. This is recognized by a V-shaped indentation at the bladder neck

68. The degree of protrusion of the prostate into the bladder may have some predictive value for bladder outlet obstruction It has been shown that intravesical prostatic protrusion correlates relatively well with formal urodynamic evaluation of bladder outlet obstruction ( Chia et al., 2003; Keqin et al., 2007) The measurement is obtained by drawing a line corresponding to the bladder base on sagittal scan and measuring the perpendicular distance from the bladder base to the greatest protrusion of the prostate into the bladder

69. In this sagittal view of the prostate, the middle lobe extends into the bladder (A). The bladder base is defined by line B. The length of line A is the intravesical prostatic protrusion (IPP).

70. Procedural Applications Transabdominal ultrasound-guided percutaneous bladder aspiration with or without catheter placement has been successfully used in neonates, children, and adults ( Gochman et al., 1991; Wilson and Johnson, 2003) It has also been employed for treatment of bladder stones ( Ikari et al., 1993; Sofer et al., 2004). Ultrasound-guided aspiration has also been used for peritoneal drainage after bladder perforation (Manikandan et al., 2003).

71. Limitations Transabdominal pelvic ultrasonography yields limited information in patients with an empty bladder The ability to identify distal ureteral obstruction, bladder stones, and bladder tumors requires a full bladder Pelvic structures may be difficult to evaluate in patients with a protuberant abdomen or panniculus Automated measurement of bladder volume or residual urine, although using ultrasonography , is not an imaging study

72. (A) Transabdominal ultrasound is extremely useful for measuring prostatic volume and evaluating prostatic morphology. The volume of the prostate can be calculated using this formula: prostate volume ( mL ) = width (cm) × height (cm) × length (cm) × 0.523. (B) In this midsagittal view of the prostate, the bladder neck is identified as a Vshaped indentation (arrow). Note the characteristically hyperechoic trigone (arrowhead).

73. Ultrasonography of the Scrotum Urologists have a surgical understanding of the anatomy and extensive experience with the diagnosis and treatment of disorders that affect the scrotum Because the scrotum and its contents are superficial, high-frequency transducers may be employed to yield excellent and detailed anatomic and physiologic information

74. Technique The examination should be carried out in a quiet room that is adequately warm for patient comfort The patient should be supine with the scrotum supported on a towel or on the anterior thighs Complete but gentle contact between skin and transducer is essential because excessive pressure results in movement of testis or compression of the testis Compression may change echogenicity and obscure fine anatomic detail. In addition, compression may significantly alter volume measurements.

75. Scrotal ultrasonography is performed with a high-frequency linear array transducer, generally in the range of 7 to 18 MHz. Transducers may be 4 to 7.5 cm in width. Imaging should be done in a systematic fashion and should include sagittal and transverse views of the testis. The sagittal view should proceed from the midline medially and then laterally and from the midtransverse section of the testis to the upper pole and the lower pole of the testis.

76. Indications 1. Assessment of scrotal and testicular mass 2. Assessment of scrotal and testicular pain 3. Evaluation of scrotal trauma 4. Evaluation of infertility 5. Follow-up after scrotal surgery 6. Evaluation of the empty or abnormal scrotum

77. Normal Findings It is important to document the size and, if appropriate, the volume of the testes. It is important to compare the testes for echogenicity because some infiltrative processes may result in diffuse changes in a testis that would be noticed only when that testis is compared with its contralateral mate

78. In this longitudinal view the head of the epididymis (E) is seen to the left, and the lower pole of the testis is to the right. Normal testicular sonographic anatomy is characterized by a homogeneous finely granular appearance of the testis

79. lymphomatous or leukemic involvement of the testis may result in a diffusely hypoechoic and homogeneous appearance, which may be unilateral ( Mazzu et al., 1995).

80. If paratesticular fluid is present, the epididymis and the testicular and epididymal appendages are more easily identified

81. Normal testicular blood flow may be demonstrated with color or power Doppler (Barth and Shortliffe , 1997) Intratesticular blood flow is primarily supplied by the testicular artery, which ultimately divides to supply the individual testicular septa. The fibrous septa coalesce to form the mediastinum testis, which is a hyperechoic linear structure seen in the sagittal plane

82. (A) Normal intratesticular blood flow by power Doppler; note the epididymal cyst (arrowhead). (B) Increased blood flow in an irregular pattern demonstrated by color Doppler was associated with necrotizing vasculitis ; note the relatively hypoechoic areas of decreased vascularity (arrows).

83. The sagittal image of this testis demonstrates a common anatomic finding, the hyperechoic mediastinum testis (arrows). The mediastinum testis is a normal structure resulting from the coalescence of the fibrous septa of the testis.

84. Procedural Applications The testis provides easy access for ultrasound localization of internal structures and therefore for percutaneous access In particular, small nonpalpable lesions can be localized by ultrasound, guiding placement of a needle for percutaneous biopsy or injection of a dye for localization during open biopsy ( Buckspan et al.,1989). Current therapeutic applications using ultrasound guidance include percutaneous testicular sperm aspiration (TESA) ( Belker et al., 1998; Friedler et al., 1997; Khadra et al., 2003) or from percutaneous epididymal sperm aspiration (PESA) (Belker et al., 1998; Craft et al., 1995; Lin et al, 2000; Meniru et al., 1998a; 1998b; Pasqualotto et al., 2003; Rosenlund et al., 1998).

85. Sonoelastography Two recent studies have used real-time elastography to differentiate benign from malignant testicular lesions because it is postulated that malignant lesions have an increased stiffness resulting from a higher concentration of vessels and cells compared with surrounding tissues.

86. Limitations Caution should be used when interpreting Doppler flow studies in the evaluation of suspected testicular torsion The hallmark of testicular torsion is the absence of intratesticular blood flow Paratesticular flow in epididymal collaterals may appear within hours of torsion

87. Demonstration of normal bilateral intratesticular blood flow by color Doppler.

88. Ultrasonography of the Penis and Male Urethra Technique Penile and urethral ultrasonography is best performed with a 12- to 18-MHz linear array transducer for optimum resolution The technique for penile and urethral ultrasonography includes imaging the phallus in the longitudinal and transverse plane. Ventral and dorsal surfaces of the phallus can be interrogated. The examination is performed beginning at the base of the penis and proceeding distally to the glans

89. It is possible to get an image of the proximal urethra and corporal bodies by scanning through the scrotum or the perineum. It may be helpful when evaluating the penile urethra, especially for stricture disease, to inject a sterile gel into the urethra in a retrograde fashion.

90. Indications 1. Evaluation of penile vascular dysfunction 2. Documentation of fibrosis of the corpora cavernosa 3. Localization of foreign body 4. Evaluation of urethral stricture 5. Evaluation of urethral diverticulum 6. Assessment of penile trauma or pain

91. Normal Findings Scanning of the external portion of the phallus can be performed either from the dorsal or ventral surface Transverse scanning of the phallus reveals the two corpora cavernosa dorsally and the urethra ventrally The sagittal view of the phallus demonstrates the corpora cavernosa with a hyperechoic , double linear structure representing the cavernosal artery The urethra is collapsed except during voiding.

92. A transverse view of the phallus with the transducer placed either on the dorsal or ventral surface. Note the compression of the urethra and corporal spongiosum compression in the ventral projection with minimal pressure applied to the phallus.

93. (A) In the transverse plane scanning from the dorsal surface of the midshaft of the penis, the corpora cavernosa (CC) are paired structures seen dorsally whereas the corpus spongiosum (CS) is seen ventrally in the midline. A calcification (Ca++) is seen between the two CC with posterior shadowing.

94. (B) In the parasagittal plane the CC is dorsal with the relatively hypoechoic CS seen ventrally. Within the CC the cavernosal artery is shown with a Ca++ in the wall of the artery and posterior shadowing

95. Perineal Ultrasound The more proximal aspects of the urethra and corpora cavernosa are best assessed through a perineal approach by placement of the transducer on the perineum The bulbar urethra with the bulbar branch of the pudendal artery as well as the proximal cavernosal bodies and the cavernosal branch of the pudendal artery can be visualized

96. (A) The internal pudendal artery gives rise to the bulbourethral artery, dorsal artery, and cavernosal artery. The most proximal aspect of the cavernosal artery is best imaged through the perineum. (From Gilbert BR: Ultrasound of the male genitalia, New York, 2014, Springer.) (

97. (B) In this schematic the bulbocavernosus muscle, also known as the bulbospongiosus muscle, is red ( Gray's anatomy of the human body, ed 20, Philadelphia, 1918, Lea & Febiger .).

98. Transperineal Ultrasound The most common application of penile ultrasound is in the evaluation of erectile dysfunction (ED) and penile curvature Primary criteria for arteriogenic ED include a PSV less than 25 cm/s, cavernosal artery dilation less than 75%, and acceleration time more than 110 msec. Cases of equivocal PSV measurements, particularly when PSV is between 25 and 35 cm/s, included asymmetry of greater than 10 cm/s in PSV between the two cavernosal arteries, focal stenosis of the cavernosal artery, cavernosal artery, and cavernosal-spongiosal flow reversal (Benson et al., 1993).

99. Transrectal Ultrasonography of the Prostate Transrectal ultrasonography of the prostate (TRUS) is the sonographic imaging procedure most commonly performed by urologists TRUS performed by the urologist enhances patient care by providing a minimally invasive procedure that gives real-time information for a rapid and accurate diagnosis.

100. Technique A high-frequency 7.5- to 10-MHz transducer is usually used. This can be a biplane or single-plane transducer (i.e., “end fire” or “side fire”) It is essential to perform a digital rectal exam before inserting the ultrasound probe. Pain or tenderness, rectal stricture, mass, lesion, and/or bleeding that is encountered when performing the rectal exam or when inserting the probe may preclude the TRUS.

101. Indications 1. Measurement of prostate volume for determination of PSAD 2. Abnormal digital rectal exam 3. Prostatic assessment with sonographic -controlled biopsy 4. Cysts 5. Evaluation for and aspiration of prostate abscess 6. Assessment for suspected congenital abnormality 7. Lower urinary tract symptoms 8. Pelvic pain 9. Prostatitis / prostadynia 10. Hematospermia 11. Infertility (e.g., azoospermia ) a. Low volume or poorly motile specimen b. Cysts c. Hypoplastic or dilated seminal vesicle d. Impaired motility e. Antisperm antibodies

102. Normal Findings Echogenicity is best evaluated by comparing the left and right side of the prostate TRUS is often indicated in the evaluation of the subfertile male. The young male prostate is homogenous with zones often difficult to visualize. The “ sonographic capsule” can be identified because of the impedance difference between the prostate and surrounding fat.

103. (A) Young male prostate. The peripheral zone ( pz ) is often hyperreflective to the central ( cz ) and transition ( tz ) zones. The cz and tz are difficult to differentiate from each other, and the fibromuscular stroma ( fs ) is positioned anterior to the urethra

104. (B) Older male prostate. The glandular and stromal elements enlarge, increasing the size of the tz and occasionally the pz . The tz is seen independent of other zones, and the cz is difficult to visualize.

105. Procedural Applications Transrectal ultrasound-guided biopsy (TRUS/BX) of the prostate is most often initially performed for a specific clinical indication, such as an elevation or change in the PSA or in an abnormal digital rectal examination High-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small acinar proliferation (ASAP) on initial biopsy are considered by some to be indications for immediate or planned repeat biopsy. Prostatic cyst aspiration is a therapeutic procedure easily performed in the office with minimal patient discomfort