Radiology

Radiology

Urinary tract ultrasound scan USS ( Figure 81.14 ) can characterise pathologies of the kidney , bladder, prostate and testis very well but is not very good for assessing the ureters unless they are significantly dilated or have sizeable pathology . The lack of radiation and contrast exposure coupled with portability and availability make USS the first imaging investigation in urological diseases. It is extremely useful in the detection of hydronephrosis (even at the bedside in an emergency), renal cysts, tumours, scarring and stones. Stones classically produce an acoustic shadow , but USS is not the most sensitive imaging modality for detecting renal stones. USS is extensively used for the insertion of a percutaneous nephrostomy (PCN) to drain an obstructed renal collecting system. It is sometimes used to further characterise renal lesions detected by other modalities such as computed

Figure 81.7 A normal urethra on urethroscopy. Figure 81.8 The appearance of normal bladder mucosa on cystos copy: a normal right ureteric ori /f_i ce (yellow arrow) at the end of the interureteric bar (red arrow). (b) Figure 81.9 (a, b) Bladder wall trabeculation (yellow arrows) and saccules (red arrows) seen on cystoscopy. (Image (a) courtesy of The Center for Reconstructive Urology, CA, USA.)

Figure 81.10 An endoscopic view of the prostatic urethra with the verumontanum at 6 o’clock (red arrow) and the bulging right (black arrow) and left (blue arrow) lobes of the prostate.

tomography (CT) or MRI, particularly for haemorrhagic cysts versus solid lesions. USS can detect bladder tumours, calculi, a thickened, trabeculated bladder wall in patients with BOO and large bladder diverticula. It can also be used to determine the residual urine after micturition. In addition, USS is frequently employed to investigate men with scrotal swellings and has a role to play in the assessment of urethral stricture disease. Transrectal ultrasound scan TRUS is often performed in conjunction with biopsy of the prostate. It requires the use of a special probe ( Figure 81.15 that provides transverse as well as sagittal views of the prostate Summary box 81.7 Ultrasound scan /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF ( Figure 81.16 ). TRUS is most often used to guide a prostate biopsy in men suspected to have prostate cancer. The classic abnormality associated with prostate cancer is a hypoechoic area in the peripheral zone but this is rarely found in the absence of a palpable abnormality on DRE. Typically , 12 or more systematic biopsies are taken using a biopsy device such as that shown in Figure 81.17 . Additional biopsies may be ) taken from areas that are suspected to be malignant.

(b) Figure 81.11 Bladder calculi seen on cystoscopy. Stones may be multiple (a) or single (b) . The stone in (b) has a characteristic shape and is referred to as a ‘jack’ stone. (Image (b) reprinted with permission from Medscape Drugs & Diseases (http://emedicine. medscape.com/) , 2017, available at: http://emedicine.medscape. com/article/2120102-overview) . Figure 81.12 Papillary bladder tumours seen at cystoscopy near the right ureteric ori /f_i ce (arrow) (courtesy of Tim Nathan). Figure 81.13 A /f_l exible ureteroscope (top) and a semirigid uretero

scope (bottom). Frequently used to screen patients with suspected urological pathology Frequently part of a haematuria clinic protocol An excellent method to detect hydronephrosis Can be performed at the bedside in critically ill patients Recently has been combined with contrast enhancement in certain settings, such as in the assessment of renal cysts

(c) (e) Figure 81.14 Ultrasound scan showing: (a) hydronephrosis (courtesy of Dr Bruno Di Muzio, Radiopaedia.org, rID: 21885); (b) renal cyst (courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 21139); (c) tumour (courtesy of Wendy Boller); (d) medullary sponge kidney with renal calculi – note the stone gives rise to an acoustic window (courtesy of Dr Bruno Di Muzio, Radiopaedia.org, rID: 12141); (e) /uni00A0 angiomyolipoma (arrow). (d) renal Figure 81.15 Transrectal probe demonstrating the diagonal channel for the biopsy needle (arrow).

Transperineal template biopsies of the prostate Transperineal template biopsies of the prostate (TPTBP) are increasingly used clinically and may replace TRUS-guided prostate biopsies as a first-line test. Currently , TPTBP are used to further evaluate men with a negative TRUS-guided prostate biopsy in whom the PSA trend remains suspicious, or younger men for whom a diagnosis of low-risk prostate cancer has been made and in whom it is important to exclude more significant disease in other parts of the prostate (most notably in the anterior aspects of the gland) not easily accessible via the transrectal route. TPTBP are usually performed under local anaesthetic and have a much lower risk of sepsis than TRUS-guided biopsies. Summary box 81.8 Prostate biopsies /uni25CF /uni25CF /uni25CF Kidneys–ureters–bladder radiograph A plain radiograph of the abdomen and pelvis that includes the regions of the body occupied by the KUB is frequently called an x-ray KUB ( Figure 81.18 ). In the normal setting, soft-tissue outlines of the kidneys are commonly seen but normal ureters and bladder will not be seen. The commonest indication for a KUB radiograph is to screen patients for the presence of urinary tract calculi. Patients who have had a CT scan resulting in the diagnosis of a urinary tract calculus often have a supplementary KUB radiograph to determine if a plain radiograph can be used in the subsequent follow-up of the patient. Phleboliths (thrombosed, calcified veins in the pelvis) can easily be mistaken for distal ureteric stones. Finally , a KUB radiograph is often used to check for correct positioning of a ureteric stent. Intravenous urography Intravenous urography (IVU) continues to be frequently used in the evaluation and management of patients with urinary

Figure 81.16 Views of the prostate on a transrectal ultrasound scan. (a) On the transverse image, the normal prostate demonstrates an anterior transition zone (TZ) and a posterior (cow-horn-shaped) peripheral zone (PZ). Asterisk indicates the verumontanum. (b) sagittal image the bladder is seen above the prostate (arrowheads) as well as the seminal vesicles (arrow). (a) (b) Figure 81.17 (a) A biopsy device used for prostatic biopsy. (b) cores taken from the right and left prostatic lobes during transrectal ultrasound scanning. On the TRUS has been the traditional method of guiding prostate biopsies TPTBP are becoming increasingly popular TPTBP have a much lower sepsis risk than TRUS biopsies Biopsy

stones and urinary TB in many parts of the world, even though it provides less information than a CT scan. This is primarily due to its wider availability , lower cost and lower radiation exposure ( Figure 81.19 ). Retrograde urethrogram and voiding cystourethrogram During a retrograde urethrogram (RGU), radiocontrast material is gently instilled into the urethra to delineate its anat omy . The investigation is primarily used to identify urethral strictures in men. Radiocontrast material is instilled into the bladder, through either a urethral catheter or a suprapubic Morton A Bosniak , 1929–2016, Professor of Radiology , New Y ork University (NYU) Langone School of Medicine, New Y ork, NY , USA. tube for a voiding cystourethrogram (VCUG). VCUGs are used to identify reflux into the ureter, usually in children, and for delineation of the proximal urethra in men with complete urethral strictures. They may also help in assessing bladder capacity in TB ( Figure 81.20 ). Computed tomography scan A non-contrast CT scan is the imaging modality of choice in the investigation of a patient with suspected urinary tract calculi ( Figure 81.21 ). This investigation is quick, often taking less than 2 minutes to perform, picks up most calculi and can be tailored to deliver low radiation doses. Other variations of the CT scan include a contrast CT , which can be tailored to acquire images in multiple phases (triple phase for renal tumours) and a urographic phase for urothelial tumours. A contrast CT scan of the chest, abdomen and pelvis is fre - quently used to stage patients with renal tumours ( Figure 81.22 ), muscle-invasive bladder cancer and young men with testicular cancer. CT is less fr equently used in men with prostate cancer but does have a role to play when lymph node disease is being assessed prior to treatment. Cysts are a frequent incidental finding on USS and CT - scans of the kidneys. In 1986, a classification of renal cysts based on CT criteria, known as the Bosniak classification, was devised. This classification can also be applied to MRI.

(c) Figure 81.18 (a) Left lower pole renal stone on a plain kidneys– ureters–bladder radiograph (courtesy of Professor Frank Gaillard, Radiopaedia.org, rID: 12555). (b) A staghorn calculus in the left kidney /uni00A0 (courtesy of Dr Natalie Yang, Radiopaedia.org, rID: 9733). (c) Right lower pole calculi and steinstrasse (multiple stone fragments from shock-wave lithotripsy to break the kidney stone), leading to the formation of a ‘stone street or steinstrasse’ in the distal right ureter (arrow) (courtesy of Dr Ali Abougazia, Radiopaedia.org).

It is used to predict the likelihood of malignancy in the lesion. Based on this classification ( Figures 81.23 and 81.24 majority of cysts are category I and II and do not require treatment or follow-up imaging. Category IIF (‘F’ indicating the need for follow-up) cysts do require further imaging but the duration of this is uncertain. Category III cysts have a risk of malignancy of 30–100% and should undergo a biopsy to identify those patients requiring surgery . Category IV ‘cysts’ have an incidence of malignancy of 67–100% and surgical removal should be considered. ), the Magnetic resonance imaging MRI scanning has a significant role to play , either on its own or as an adjunct to other cross-sectional imaging modalities, in the staging of a number of urological cancers, particularly prostate cancer. Modern MRI techniques utilise both anatomical and

(b) Figure 81.19 Intravenous urogram plain (a) and 5-minute (b) demonstrating a partial staghorn stone in the left kidney. The right kidney is normal. A 5-minute /f_i lm shows contrast entering the pelvica lyceal system and helps in identifying the location of the stone. Figure 81.20 Cystogram in a patient with tuberculosis, demonstrating a small ‘thimble’ bladder and re /f_l ux into the right kidney. (a) (b) (c) (d) Figure 81.21 (a) A non-contrast computed tomography scan demon

strating bilateral renal calculi (courtesy of Dr Jeremy Jones, Radiopae

dia.org, rID: 6211); (b, c) left ureteric calculus in the axial and coronal reconstructions (courtesy of Dr Raju Sharma and Dr Ankur Goyal); (d) bilateral lower ureteric calculi (courtesy of Dr Raju Sharma and Dr Ankur Goyal). /f_i lms,

functional imaging and are known as multiparametric MRI (mpMRI). Anatomical imaging is based on standard MRI techniques (T1- and T2-weighted images) and functional imaging is based on di ff usion-weighted imaging (DWI) (for enhanced (DCE) imaging (for tissue perfusion assessment after intravenous contrast administration) ( Figure 81.25 ). The multiple parameters assessed in the scan are combined in a fiv e-point scoring system, called PI-RADS (Prostate Imaging – Reporting and Data System), to assign a likelihood (from 1, benign to 5, highly suspicious) that prostate cancer is present within the abnormality detected on mpMRI of the prostate. The lesions identified on mpMRI can be specifically targeted for biopsy using novel technologies. MRI images can be fused with real-time TRUS-USS images to guide the biopsies to these abnormal areas in a similar manner to TRUS biopsy . Such ‘fusion’ biopsies require specialised workstations. Similar scoring systems are being used to assess bladder cancer. Summary box 81.9 Magnetic resonance imaging /uni25CF /uni25CF /uni25CF /uni25CF

Figure 81.22 Computed tomography scan demonstrating a large left renal tumour with involvement of the left renal vein (arrow) (courtesy of Dr Laughlin Dawes, Radiopaedia.org, rID: 35937). I ~0% are malignant IIF ~5% are malignant III ~50% are malignant Used to stage many urological cancers mpMRI has a signi /f_i cant role in the assessment of men with suspected prostate cancer mpMRI is increasingly used prior to prostate biopsy. Prebiopsy MRI permits selection of biopsy technique (TRUS versus TPTBP) Prebiopsy MRI assists with targeting of biopsies II ~0% are malignant Figure 81.23 Bosniak classi /f_i cation of renal cysts. The classi /f_i

cation depends on the characteristics of the cyst wall, septae, solid component and enhancement on con

trast administration. IV ~100% are malignant

Figure 81.24 Computed tomography scans showing cysts of various categories: (d) Bosniak III cyst; (e) Bosniak IV cyst (courtesy of Dr Raju Sharma and Dr Ankur Goyal). (a) (c) Figure 81.25 Multiparametric magnetic resonance images of a patient with prostate cancer. (c) Apparent diffusion coef /f_i cient (ADC). (d) Dynamic contrast enhanced (DCE). The tumour appears dark on the axial T2-weighted image /uni00A0 (arrow); the corresponding area shows restricted diffusion on the DWI and ADC images as well as abnormal contrast enhancement on the DCE axial image (within the prostate, the red colour denotes abnormal areas that are possibly malignant) (courtesy of Janet Cochrane Miller, Radiology Rounds, Massachusetts General Hospital).