This book has the unique goal of providing the greatest utility to the modern radiologist practicing diagnostic imaging of the genitourinary system. In preparing this book, a critical decision was made about the style of presentation of information.
Preface
Contributors
Kratzik
Combination of both sequences indicates cancer, which was confirmed by six directed right anterior biopsy (Gleason score 7, 13 mm of Ca). b): The x-axis of the spectral trace from the voxel represents frequency. Gleason score 7 (3+4).involving the three right sextants. a): right PZ hyposignal (arrow) and heterogeneous signal of the left PZ.
Adrenal Imaging
Introduction
Threshold values greater than 60% for absolute and 40% for relative enhancement washout have been shown to be over 90% specific for adenoma diagnosis. Loss of signal intensity of the adrenal mass using the spleen as a reference organ, on out-of-phase, compared to in-phase pulse sequence is diagnostic for the presence of intracellular lipid.
Cushing’s syndrome
Use of contrast-enhancing washout values is also useful in distinguishing between adenomas and malignant lesions. Qualitative analysis: The main sequence of adrenal MR imaging protocol is chemical shift imaging sequence.
Clinical features
Includes Cushing's disease (excess adrenocorticotropic hormone [ACTH] produced by pituitary adenomas) and Cushing's syndrome (ectopic ACTH syndrome or primary kidney disease resulting in glucocorticoid secretion independent of ACTH stimulation). Detection of an elevated cortisol level at midnight suggests Cushing's syndrome (midnight plasma level or late-night salivary cortisol sampling).
Pathophysiology
If Cushing's disease is ACTH-dependent and there is no clear pituitary lesion on MRI, petrous sinus sampling can be continued with corticotropin-releasing hormone (CRH) stimulation: a central-to-peripheral ACTH gradient is suggestive of Cushing's disease, whereas no gradient is to ectopic secretion of ACTH.
Treatment
Imaging findings
Primary hyperaldosteronism
Axial out-of-phase MR image shows nodular thickening of the adrenal glands bilaterally in a patient with Cushing's syndrome. Adrenal cortical carcinomas can also cause Cushing's syndrome (see below for imaging images of adrenocortical carcinoma).
Introduction
Pheochromocytoma
Show less than 16.5% loss of out-of-phase signal intensity compared to in-phase MRI pulse sequences. Pheochromocytomas occur associated with various syndromes such as; multiple endocrine neoplasia (MEN2), Von Recklinghausen neurofibromatosis (NF1) and Von Hippel-Lindau disease (VHL) (Fig. 1.7).
Adrenal cortical carcinoma
50-60% of patients have symptoms related to hormone hypersecretion (most commonly Cushing's syndrome and virilization). Mitotane (an adrenolytic) may be used as adjuvant therapy; controls endocrine symptoms in 50% of patients but generally does not affect survival.
Adrenal incidentaloma
Workup and treatment
Hypointense on T1-weighted images and hyperintense on T2-weighted images, with no soft tissue component and no internal enhancement (Fig. 1.11). Axial contrast enhanced CT shows a left adrenal mass with an intralesional fat area indicated by a negative attenuation value of -28 HU (arrow).
Retroperitoneal Masses
- Introduction
- Retroperitoneal anatomy
- Pathological conditions
- Primary solid retroperitoneal tumors
These spaces are separate, but they open inferiorly at the level of the pelvis, where the retroperitoneum space communicates with the extraperitoneal space in the pelvis, and the two spaces become contiguous. Identification of the retroperitoneal spaces on diagnostic imaging is useful in elucidating the etiologies of various solid or cystic masses.
Clinical problem – key concepts
Gerota's anterior renal fascia (yellow line) separates the perirenal space from the anterior retroperitoneum. Vague gastrointestinal symptoms may be caused by intestinal displacement or compression, while urological or neurological signs are uncommon.
Role of diagnostic imaging
The majority (80-85%) of primary retroperitoneal tumors are malignant, but they represent only 0.4% of all malignant tumors. Primary retroperitoneal tumors can be schematically divided into two groups based on their frequency in clinical practice: common retroperitoneal tumors and rare primary retroperitoneal masses (Tables 1.1 and 1.2).
General imaging criteria
Abdominal sonography on longitudinal scan showing a large solid retroperitoneal abdominal mass with ill-defined profiles infiltrating various abdominal structures.
Specific imaging criteria
Retroperitoneal lymphoma
Malignancy can be suspected based on the infiltrative nature and detection of metastases. Unilocular or multilocular cystic mass with water density and mild wall contrast enhancement.
Imaging criteria
Cystic retroperitoneal masses
On CT, a mature teratoma in the retroperitoneum consists of a complex mass containing a well-circumscribed fluid component, fatty tissue and calcification (Fig. 2.8). Mullerian cyst. M¨ullerian cyst in the retroperitoneum is an extremely rare disease that is thought to be a subtype of urogenital cyst.
Retroperitoneal metastases
Retroperitoneal fibrosis (Ormond’s disease)
Imaging criteria Conventional radiology
Retroperitoneal fluid collections (traumatic and non-traumatic)
Retroperitoneal traumatic hematomas Clinical problem – key concepts
To facilitate the clinical management of hematomas resulting from blunt trauma, the retroperitoneum can be anatomically divided into three zones. Zone I is the upper central area extending caudally from the aortic hiatus of the diaphragm to the sacral promontory. CT is the imaging modality of choice for evaluating stable patients with blunt or penetrating trauma.
Retroperitoneal non-traumatic hematomas Clinical problem – key concepts
CT transverse scan without contrast shows a non-homogeneous mass with high density values due to recent bleeding. Large fluid collection extending from the left retroperitoneum to the pelvis with swelling of the psoas and hip muscle.
Retroperitoneal urinoma Clinical problem – key concepts
A large multiloculated collection extending from the left kidney to the pelvis with low density values due to a long-standing urinoma. They are particularly useful in patients who cannot receive CT with intravenous contrast because of elevated creatinine levels or who are allergic to iodinated contrast or who have received a kidney transplant.
Retroperitoneal abscesses Iliopsoas abscesses
Imaging of Renal Artery Stenosis
- Introduction
- Clinical features
- Pathology
- Imaging of suspected renal artery stenosis
In cases where there is a high clinical suspicion of renal artery stenosis and secondary hypertension, radiological examination can often be useful. There are a number of studies available using different modalities for the evaluation of suspected renal artery stenosis (RAS).
Ultrasound
Ultrasound findings in RAS
Nuclear Medicine Angiotensin Converting Enzyme (ACE) Inhibition Renogram
CT Angiography
Images of the kidneys from 1–20 minutes (a) demonstrate prolonged cortical retention in the left kidney relative to the right. This is due to decreased urine flow in the left kidney due to renal artery stenosis.
MR Angiography
An eccentric area of narrowing near the origin of the renal artery, often containing calcification, suggestive of atherosclerotic RAS. Eccentric narrowing at the beginning of the right renal artery (arrow), characteristic of stenosis secondary to atherosclerosis (a), is contrasted with multiple stenoses in the middle right renal artery (arrow) of a patient with fibromuscular dysplasia (b).
Renal Masses
Introduction
Symptomatic renal carcinoma
Imaging approach
- Incidental renal masses
- Patients with a known cancer (other than RCC)
- Renal mass in patients with symptoms
- Vascular lesions presenting as a renal mass
- Renal mass in patients with cystic disease
- Treatment
A 1.8 cm clear cell carcinoma was removed with partial nephrectomy from the lower pole of the right kidney. Acquired cystic disease of the kidney, seen in patients after several years of dialysis, has a markedly increased propensity to develop RCC (Fig. 4.19).
Non-neoplastic Renal Cystic Lesions
Introduction
Classification
Cystic lesions affecting renal cortex
Simple renal cyst
Cystic lesions of renal medulla
Medullary sponge kidney
Dilated collecting ducts in the renal medulla, which contain small stones seen on IVU or CT urography (CTU), are key to the diagnosis of medullary fungal kidneys. In the excretory phase of CTU, dilated collecting ducts are seen in the renal medulla.
Uremic medullary cystic disease (Juvenile Nephronophthisis)
Medullary necrosis
Contrast cavities the size of a grain of rice in the papilla, which are pathognomonic of the medullary form of renal papillary necrosis. Contrast-filled fissures in the renal parenchyma and filling defects caused by necrotic, detached papillae may be in the medullary cavities, renal pelvis, or ureters on CTU (Figure 5.5).
Pyelogenic cyst (calyceal diverticulum/cyst)
Cystic diseases affecting both the cortex and medulla
Autosomal recessive polycystic kidney disease
This is similar to polycystic infantile disease except that renal involvement is less and hepatic involvement is the predominant feature of the disease. Increased echogenicity of the portal tracts in the liver due to periportal fibrosis.
Autosomal dominant polycystic kidney disease (ADPKD)
Calcification can develop in the wall of the cyst or in the renal parenchyma between the cysts. These measurements are useful for clinical trials testing new drugs aimed at slowing the progression of the cystic changes in the kidneys.
Multicystic dysplastic kidney
CT urography (CTU) in the nephrographic phase using fine collimation is more sensitive than US in demonstrating small renal cysts and can be used to rule out ADPKD in patients over 20 years of age. Ureteropelvic junction obstruction and vesicoureteral reflux (VUR) are the most common defects in the contralateral kidney.
Acquired cystic kidney disease (ACKD)
The hyperplasia may develop into tubular papillary adenomas which may progress in equal proportions to clear cell or papillary renal cancer. Dilated calyces of the right kidney are secondary to tuberculous stricture of the right ureter (not shown in this figure).
Miscellaneous acquired cystic lesions of the kidneys
Extraparenchymal renal cysts
Ravine D, Gibson RN, Walker RG, Sheffield LJ, Kincaid-Smith P, Danks DM (1994) Evaluation of ultrasound diagnostic criteria for autosomal dominant polycystic kidney disease 1. Thomsen HS, Levine E, Meilstrup JW, Van Sluke MA, Edgar KA , Barth JC, Hartman DS (1997) Renal cystic disease. Eur.
Urological and Vascular Complications Post-renal
Introduction
Vascular complications
Thrombosis
MRA is particularly beneficial in cases with patchy perfusion of the graft by Doppler ultrasound, as it can distinguish between severe rejection and vascular thrombosis. This appearance indicates total infarction of the kidney which was proven during the operation. a) Anterior wedge-shaped subcapsular segment shows no color flow signals on power Doppler US due to infarction.
Transplant renal artery stenosis
Urological complications
Urinary leakage
Pathology
Imaging findings Ultrasound
Ureteric strictures
T2 MRU is safe and provides accurate information about the level and length of the ureteric stricture and the degree of hydronephrosis, especially in patients with marked renal impairment (Fig. 6.10a). Early strictures are usually successfully managed by antegrade balloon dilatation and stent placement. a) Mild pelvic enlargement is frequently seen in the transplanted kidney without obstruction.
Post-transplant lymphocele
MRU provides an accurate image of the lymphoid in relation to the transplanted kidney, ureter and urinary bladder. Ultrasound is the initial screening tool to diagnose such pathology, while MRI provides reliable detailed delineation of the joint and graft.
Delayed graft function (DGF)
If an isotope study is normal early postoperatively and becomes abnormal afterward, acute rejection should be suspected. Recent reports had confirmed the great ability of functional MRI in differentiating between different etiologies of DGF, namely acute rejection and acute tubular necrosis.
Summary
Post-transplant bladder malignancy
El-Mekresh M, Osman Y, Ali-El-Dein B, El-Diasty T, Ghoneim M (2001) Urological complications after living donor kidney transplantation.BJU Int. Vascular complications after living donor kidney transplantation: Study of risk factors and effects on graft and patient survival.J. Pfaff W, Howard R, Patton Pet al. 1998).
Urinary Tract Injuries
Introduction
Renal trauma
Clinical presentation and evaluation
Imaging Techniques
A subcapsular hematoma appears as an elliptical collection of fluid that lines the contour of the right kidney. Larger renal lacerations may be associated with devascularization of the renal parenchyma or extension to the renal collecting system.
Management
Adrenal trauma
Clinical presentation
Imaging CT
Hematomas should show no significant change in attenuation, while adenomas should show more than 50% washout.
Clinical management
Ureteral trauma
Injuries to the ureter after blunt trauma typically occur at the ureteropelvic junction (UPJ), where acute flexion or extension can tear or deflate the ureter. Almost all ureteral injuries after blunt trauma are associated with injuries to other abdominal organs or a major blood vessel.
Imaging
Bladder trauma
A normal appearance of the bladder on IVU or in the excretory phase of CTU does not exclude a bladder injury. Static or CT cystography with retrograde filling of the bladder with contrast will be required to rule out bladder injury.
Management Contusion
Urethral trauma
Pure injury of the base of the bladder with periurethral extravasation simulating a true type IV urethral injury (Fig. 7.8k–m). Contrast clearly extends to the level of the membranous urethra, but not beyond the UG diaphragm (lower arrow). i) Diagrammatic illustration reproduced from SM Goldman et al,.
Penile and scrotal trauma
Women with proximal urethral disruptions should undergo immediate investigation with realignment of the urethral ends or primary reanastomosis via a catheter. For women with distal urethral lacerations, urethral catheterization with primary closure of the vaginal laceration is sufficient.
Clinical presentation Injuries to the penis
Imaging The penis
Disruption of the tunica albuginea is pathognomonic of testicular rupture and requires urgent surgical intervention, especially when testicular tissue is seen protruding from the tear. Tunic lacerations can be difficult to determine on ultrasound because of the presence of severe intratesticular and extratesticular hematomas.
Surgical management Injuries to the penis
Ill-defined testicular margins and heterogeneous echotexture with areas of focal hyper- and hypoechogenicity corresponding to areas of hemorrhage and infarction, respectively, are consistent with testicular rupture. US can be used to determine vascular injury or identify bullet fragments or other foreign bodies, in addition to findings in blunt trauma.
Injuries to the scrotum
Urinary Tract Infections
Symptomatic urinary tract infection in children
Symptoms depend on the age of the patient and the degree of infection (bladder or kidney involvement). Older children may report symptoms that point to upper or lower urinary tract infection.
Laboratory tests and findings Urine sample
Pathology Acute infection
Healing may be complete and leave no detectable residue, or result in permanent kidney damage. Various combinations of ultrasound (US), DMSA scintigraphy, and voiding cystourethrography (VCUG) can be used to investigate children with first-time UTI.
Evaluation of the urinary tract Ultrasonography (US)
Symptomatic upper urinary tract infection in adults
Imaging of the urinary tract in adults is usually considered only after repeated episodes of UTI or if a complication is suspected. Adults with repeated episodes of febrile UTI/pyelonephritis should have urinary tract imaging to reveal any underlying cause.
Emphysematous pyelonephritis
CT is the method of choice as it is very sensitive for detecting even very small amounts of gas. CT shows collections of gas in the parenchyma (focal or widespread), in combination with signs of inflammation (renal swelling, irregular, reduced contrast enhancement and perirenal stranding).
Xanthogranulomatous pyelonephritis
Demonstration of gas in the renal parenchyma, collecting system, or perirenal tissues by any imaging modality in the clinical setting of UTI should raise the suspicion of emphysematous pyelonephritis. Contrast-enhanced CT shows a markedly enlarged right kidney with a large antler stone in the renal pelvis and multiple peripheral renal calcifications.
Urinary tract infection in the immunocompromised patient
The findings on urinary tract imaging are similar to those in other patients with infectious diseases of the urogenital organs. It can precipitate in the urine and cause indinavir 'calculi', which can obstruct the urinary tract.
Tuberculosis
