O ff i c e - B a s e d U l t r a s o u n d f o r t h e U rol o g i s t Martha K. Terris, MDa,b,*, Zachary Klaassen, MDa KEYWORDS Office ultrasonography Renal ultrasonography Bladder ultrasonography Scrotal ultrasonography Penile Doppler ultrasonography Prostate ultrasonography
KEY POINTS Renal ultrasonography allows assessment of a dilated upper urinary tract particularly in pediatric patients, assessment of flank pain during pregnancy, and evaluation of hematuria in patients who are not candidates for intravenous pyelography, contrast computed tomography, or magnetic resonance imaging. Bladder ultrasonography allows assessment of postvoid residual in male patients with benign prostatic hyperplasia, particularly during the initial workup. Scrotal ultrasonography allows assessment of a scrotal or testicular mass or swelling, assessment of acute scrotal pain, and assessment of male infertility. Penile Doppler ultrasonography allows assessment of the cavernosal arteries and their spectral waveform evolution following intracavernosal injection of a pharmacostimulant in patients with erectile dysfunction. Transrectal ultrasound of the prostate is the most common modality for imaging the prostate during biopsy; new modalities include color Dopper prostate ultrasonography, three-dimensional ultrasonography, and elastography of the prostate.
Ultrasonography provides the busy office urologist with a minimally invasive, low-risk imaging modality that is easily accessible in the clinic setting. The basic concepts behind ultrasound imaging involve using a frequency (number of sound waves per second, measured in hertz [Hz]) too high for the human ear to hear.1 Ultrasound waves are generated by a transducer, which is housed in an ultrasound probe that is shaped for the desired application. These waves are then transmitted to the tissue of interest and waves that reflect (or echo) after bouncing off the tissue of interest are incorporated by a receiving element in the transducer. Through a process called acoustic-
electric conversion, the transducer transforms the sound energy into electrical energy, which is processed by the ultrasound console computer to generate white pixels corresponding to returning signals displayed on a black background.2 This article reviews the basic applications of ultrasound imaging in the office setting, including renal, bladder, scrotal, penile Doppler, and prostate ultrasonography.
RENAL ULTRASONOGRAPHY Given a urologist’s knowledge of the anatomy of the kidney and retroperitoneum, performing a focused retroperitoneal ultrasound in the office setting can be useful for specific clinical
Funding Sources: None. Conflict of Interest: None. a Department of Surgery, Section of Urology, Medical College of Georgia-Georgia Regents University, 1120 15th Street, Augusta, GA 30912, USA; b Multidisciplinary Genitourinary/Prostate Team, Georgia Regents University Cancer Center, 1411 Laney Walker Boulevard, Augusta, GA 30912, USA * Corresponding author. Department of Surgery, Section of Urology, Medical College of Georgia-Georgia Regents University, 1120 15th Street, Augusta, GA 30912. E-mail address: [email protected] Urol Clin N Am 40 (2013) 637–647 http://dx.doi.org/10.1016/j.ucl.2013.07.006 0094-0143/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved.
urologic.theclinics.com
INTRODUCTION
638
Terris & Klaassen indications. The ultrasound probe and transducer for renal ultrasonography is a 3.5- to 5.0-MHz curved probe; a 6- to 10-MHz transducer may be used for pediatric patients.3 The patient is placed in the supine position and scanning begins in the midclavicular line for the kidney of interest. In the sagittal plane, the probe is moved laterally until a midsagittal view of the kidney is obtained; when analyzing the image, the upper pole of the kidney is located on the left side of the monitor (Fig. 1). Imaging of the kidney in the transverse plane is possible by rotating the probe 90 counterclockwise and the kidney is scanned from upper to lower pole. Important office-based indications for renal ultrasound include follow-up of hydronephrosis on prenatal ultrasound, assessment of a dilated upper urinary tract particularly in pediatric patients, assessment of flank pain and monitoring ureteral stent position during pregnancy, and evaluation of hematuria in patients who are not candidates for intravenous pyelography (IVP), contrast computed tomography (CT), or magnetic resonance imaging (MRI).3 Pediatric patients requiring renal imaging represent an important subset of patients for which renal ultrasonography is used. Postoperative followup of pediatric patients following ureteroscopic treatment of lithiasis is effective with ultrasound. Resorlu and colleagues4 found negative and positive predictive values of 97.7% and 100%, respectively, for detecting hydronephrosis at 3 months postoperatively for ureteroscopic manipulation of lithiasis. Similar to postureteroscopy upper tract surveillance, ultrasound is important for surveillance of postpyeloplasty patients and can be used to identify patients who may require a mercaptoacetyltriglycine-3 scan in the setting of postoperative deteriorating renal function.5
Recently, 3-dimensional (3D) ultrasonography has been reported when evaluating pediatric patients. 3D ultrasonography improves visualization of complex anatomy and pathologic condition in any plane and allows evaluation of a dilated collecting system with similar specificity to IVP and MR urography.6 When assessing a pregnant patient with renal colic, determining whether this is secondary to physiologic hydronephrosis or lithiasis may be challenging. In experienced hands, ultrasonography has a sensitivity of greater than 95% for diagnosis of nephrolithiasis.7 A review of 300 pregnant patients presenting with renal colic by Andreoiu and MacMahon8 found that the accuracy of ultrasonography for predicting a calculus improved from 56.2% to 71.9% when features of obstruction were present, such as the absence of a ureteric jet and an elevated resistive index. Although recent studies have suggested that low-dose CT scan may be safe and improve the efficacy of lithiasis diagnosis in pregnant patients,9 ultrasound remains an important and safe modality for diagnosing nephrolithiasis and monitoring progression of stone passage. As part of the evaluation for hematuria, the upper urinary tract has historically been evaluated with an IVP and more recently a contrast CT or MRI of the abdomen and pelvis. In patients with an elevated creatinine, a contrasted study risks further worsening of kidney function providing an opportunity for ultrasonography to evaluate the upper urinary tract. In this subset of patients, ultrasonography offers the ability to detect renal masses and cysts (Fig. 2). Mucksavage and colleagues10 analyzed 116 patients who underwent
Fig. 1. Normal renal ultrasonography: left kidney measuring 10.8 cm in length demonstrating isoechoic parenchymal echogenicity.
Fig. 2. Renal ultrasonography demonstrating a right 1.72 1.80 1.78 cm interpolar solid mass (delineated by red 1).
Office-Based Ultrasound ultrasound prior to imaging before definitive therapy. Patients also received an MRI or CT scan and they found that the size differences between CT and MRI compared with ultrasound was less than 3.5% and ultrasound correlated well with both MRI and CT (both P
KEY POINTS Renal ultrasonography allows assessment of a dilated upper urinary tract particularly in pediatric patients, assessment of flank pain during pregnancy, and evaluation of hematuria in patients who are not candidates for intravenous pyelography, contrast computed tomography, or magnetic resonance imaging. Bladder ultrasonography allows assessment of postvoid residual in male patients with benign prostatic hyperplasia, particularly during the initial workup. Scrotal ultrasonography allows assessment of a scrotal or testicular mass or swelling, assessment of acute scrotal pain, and assessment of male infertility. Penile Doppler ultrasonography allows assessment of the cavernosal arteries and their spectral waveform evolution following intracavernosal injection of a pharmacostimulant in patients with erectile dysfunction. Transrectal ultrasound of the prostate is the most common modality for imaging the prostate during biopsy; new modalities include color Dopper prostate ultrasonography, three-dimensional ultrasonography, and elastography of the prostate.
Ultrasonography provides the busy office urologist with a minimally invasive, low-risk imaging modality that is easily accessible in the clinic setting. The basic concepts behind ultrasound imaging involve using a frequency (number of sound waves per second, measured in hertz [Hz]) too high for the human ear to hear.1 Ultrasound waves are generated by a transducer, which is housed in an ultrasound probe that is shaped for the desired application. These waves are then transmitted to the tissue of interest and waves that reflect (or echo) after bouncing off the tissue of interest are incorporated by a receiving element in the transducer. Through a process called acoustic-
electric conversion, the transducer transforms the sound energy into electrical energy, which is processed by the ultrasound console computer to generate white pixels corresponding to returning signals displayed on a black background.2 This article reviews the basic applications of ultrasound imaging in the office setting, including renal, bladder, scrotal, penile Doppler, and prostate ultrasonography.
RENAL ULTRASONOGRAPHY Given a urologist’s knowledge of the anatomy of the kidney and retroperitoneum, performing a focused retroperitoneal ultrasound in the office setting can be useful for specific clinical
Funding Sources: None. Conflict of Interest: None. a Department of Surgery, Section of Urology, Medical College of Georgia-Georgia Regents University, 1120 15th Street, Augusta, GA 30912, USA; b Multidisciplinary Genitourinary/Prostate Team, Georgia Regents University Cancer Center, 1411 Laney Walker Boulevard, Augusta, GA 30912, USA * Corresponding author. Department of Surgery, Section of Urology, Medical College of Georgia-Georgia Regents University, 1120 15th Street, Augusta, GA 30912. E-mail address: [email protected] Urol Clin N Am 40 (2013) 637–647 http://dx.doi.org/10.1016/j.ucl.2013.07.006 0094-0143/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved.
urologic.theclinics.com
INTRODUCTION
638
Terris & Klaassen indications. The ultrasound probe and transducer for renal ultrasonography is a 3.5- to 5.0-MHz curved probe; a 6- to 10-MHz transducer may be used for pediatric patients.3 The patient is placed in the supine position and scanning begins in the midclavicular line for the kidney of interest. In the sagittal plane, the probe is moved laterally until a midsagittal view of the kidney is obtained; when analyzing the image, the upper pole of the kidney is located on the left side of the monitor (Fig. 1). Imaging of the kidney in the transverse plane is possible by rotating the probe 90 counterclockwise and the kidney is scanned from upper to lower pole. Important office-based indications for renal ultrasound include follow-up of hydronephrosis on prenatal ultrasound, assessment of a dilated upper urinary tract particularly in pediatric patients, assessment of flank pain and monitoring ureteral stent position during pregnancy, and evaluation of hematuria in patients who are not candidates for intravenous pyelography (IVP), contrast computed tomography (CT), or magnetic resonance imaging (MRI).3 Pediatric patients requiring renal imaging represent an important subset of patients for which renal ultrasonography is used. Postoperative followup of pediatric patients following ureteroscopic treatment of lithiasis is effective with ultrasound. Resorlu and colleagues4 found negative and positive predictive values of 97.7% and 100%, respectively, for detecting hydronephrosis at 3 months postoperatively for ureteroscopic manipulation of lithiasis. Similar to postureteroscopy upper tract surveillance, ultrasound is important for surveillance of postpyeloplasty patients and can be used to identify patients who may require a mercaptoacetyltriglycine-3 scan in the setting of postoperative deteriorating renal function.5
Recently, 3-dimensional (3D) ultrasonography has been reported when evaluating pediatric patients. 3D ultrasonography improves visualization of complex anatomy and pathologic condition in any plane and allows evaluation of a dilated collecting system with similar specificity to IVP and MR urography.6 When assessing a pregnant patient with renal colic, determining whether this is secondary to physiologic hydronephrosis or lithiasis may be challenging. In experienced hands, ultrasonography has a sensitivity of greater than 95% for diagnosis of nephrolithiasis.7 A review of 300 pregnant patients presenting with renal colic by Andreoiu and MacMahon8 found that the accuracy of ultrasonography for predicting a calculus improved from 56.2% to 71.9% when features of obstruction were present, such as the absence of a ureteric jet and an elevated resistive index. Although recent studies have suggested that low-dose CT scan may be safe and improve the efficacy of lithiasis diagnosis in pregnant patients,9 ultrasound remains an important and safe modality for diagnosing nephrolithiasis and monitoring progression of stone passage. As part of the evaluation for hematuria, the upper urinary tract has historically been evaluated with an IVP and more recently a contrast CT or MRI of the abdomen and pelvis. In patients with an elevated creatinine, a contrasted study risks further worsening of kidney function providing an opportunity for ultrasonography to evaluate the upper urinary tract. In this subset of patients, ultrasonography offers the ability to detect renal masses and cysts (Fig. 2). Mucksavage and colleagues10 analyzed 116 patients who underwent
Fig. 1. Normal renal ultrasonography: left kidney measuring 10.8 cm in length demonstrating isoechoic parenchymal echogenicity.
Fig. 2. Renal ultrasonography demonstrating a right 1.72 1.80 1.78 cm interpolar solid mass (delineated by red 1).
Office-Based Ultrasound ultrasound prior to imaging before definitive therapy. Patients also received an MRI or CT scan and they found that the size differences between CT and MRI compared with ultrasound was less than 3.5% and ultrasound correlated well with both MRI and CT (both P
