The American Association for the Surgery of Trauma (AAST) renal injury scale, most recently updated in 2018, is the most widely used grading system for renal trauma.
The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criteria for viscera...
The kidneys, ureters, bladder (KUB) radiograph is optimized for assessment of the urogenital system, and should not be confused with the AP supine abdomen view. However, in cases where the patient may have both gastrointestinal and urogenital abnormalities, all pathologies will still be reported...
AP oblique supine radiograph is a projection often used in barium studies and foreign body localization.
This view is normally performed when localizing foreign bodies or lines within the abdominal cavity. Additionally, the oblique abdominal series can be utilized in the assessment...
The PA prone radiograph is rarely performed and is often utilized when a patient is unable to lay supine. The projection is adequate for the examination of the abdominal cavity, however, not as practical for the renal structures due to magnification.
This view is useful in visualiz...
Abdominal and pelvic anatomy encompasses the anatomy of all structures of the abdominal and pelvic cavities.
This anatomy section promotes the use of the Terminologia Anatomica, the international standard of anatomical nomenclature.
Abdominal radiography can be useful in many settings. Before the advent of computed tomography (CT) imaging, it was a primary means of investigating gastrointestinal pathology and often allowed indirect evaluation of other abdominal viscera.
Although abdominal radiography has lower...
Abdominal tuberculous can manifest in almost every abdominopelvic organ:
jejunal and ileal tuberculosis
Abnormal renal rotation (renal malrotation) refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.
Abnormal testicular Doppler flow (arterial, venous, or both) can be a differential challenge. Always remember that the patient's presenting history helps quite a bit in narrowing the differential.
partial testicular torsion (<360 degrees)
venous outflow is obstructed first, resul...
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Accessory renal arteries are a common variant and are present in ~25% (range 20-30%) and are bilateral in ~10% of the population 1. Their proper identification is of utmost importance for surgical planning prior to live donor transplantation 2,3 and renal artery embolization for various reasons ...
Acquired cystic kidney disease (ACKD) is a condition that occurs in patients with end-stage renal disease (ESRD), especially when on dialysis treatment. They do not have a history of other cystic renal disease.
Its incidence increases with the amount of time a patient is azotemic...
Active surveillance describes a management option aiming at close monitoring of a specific stage in disease and minimizing adverse treatment-related effects without compromising survival at the same time. Curative or definite treatment is intended and offered upon deterioration or explicit patie...
Acute idiopathic scrotal edema (AISE) is a self-limiting condition characterized by marked edema of the skin and dartos fascia without involvement of the deeper layers, testes, or epididymis. It is an important condition to recognize in order to avoid unnecessary surgical exploration.
Acute non-traumatic abdominal pain in pregnancy requires a considered imaging approach due to the increased risks of fetal demise associated with undiagnosed diseases such as perforated acute appendicitis. Ultrasound is the first-line modality due to its wide availability and ability to diagnose...
Acute pyelonephritis (plural: acute pyelonephritides) is a bacterial infection of the renal pelvis and parenchyma most commonly seen in young women. It remains common and continues to have significant morbidity in certain groups of patients.
The incidence of acute pyelonephritis p...
Acute renal transplant rejection is a renal transplant complication that occurs within <5-7 days of the placement of the transplant. Although part of a spectrum of closely-related rejection disorders, the term is meant to distinguish this type of rejection from chronic renal transplant rejection...
Acute tubular necrosis is a common type of acute kidney injury, particularly in hospitalized patients.
Acute tubular necrosis is characterized by renal tubular cell damage and death and is usually caused by ischemic or nephrotoxic insults. Deposition of cellular debris within the tu...
Adenocarcinoma of the prostate with neuroendocrine differentiation is a malignant neuroendocrine tumor of the prostate which only differs from acinar or ductal adenocarcinoma on immunohistochemistry staining.
Adenocarcinoma of the prostate with neuroendocrine differentiation is an ac...
Adenocarcinomas of the seminal vesicles are the most common malignant primary neoplasm of the seminal vesicles.
Primary adenocarcinoma of the seminal vesicles are very rare 1,2 and can be observed at a wide age range 2.
There is a lack of specific symptoms ...
Adenocarcinoma of the urinary bladder is rare and accounts for only ~1% of all bladder cancers (90% are transitional cell carcinomas).
Metaplasia of urinary bladder induced by chronic irritation or infection can lead to adenocarcinoma. Pathological types of adenocarcinoma of the urin...
Adenomatoid tumors of the scrotum are benign, solid extratesticular lesions that can originate from the epididymis, tunica vaginalis, or spermatic cord (90% derived from the funiculus).
They are the most common extratesticular neoplasm, and most common tumor of the epididymis, and...
Adrenal abscesses are rare lesions affecting the adrenal glands and are usually encountered in the setting of disseminated infection.
Although cases have been described in both neonates and adults, no systematic literature is available on the epidemiology of adrenal abscesses.
Adrenal adenomas (alternative plural: adenomata) are the most common adrenal lesion and are often found incidentally during abdominal imaging for other reasons. In all cases, but especially in the setting of known current or previous malignancy, adrenal adenomas need to be distinguished from adr...
The adrenal glands are highly vascular. Threefold arterial supply includes the:
superior adrenal arteries: typically 6-8 in number, arising from the ipsilateral inferior phrenic artery
middle adrenal artery: one or more, arising from lateral side of abdominal aorta
inferior adrenal artery: o...
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous hemorrhage or tuberculosis. Addison disease patients only occasionally develop calcification.
sepsis: Waterhouse-Friderichsen syndrome
An adrenal collision tumor or collision tumor of the adrenal gland is an uncommon condition where two histologically distinct tumors abut each other or are in close proximity in the same adrenal gland.
Collision tumors have been reported in nearly every organ, for example, collision ...
Adrenal congestion is considered to possibly precede non-traumatic adrenal hemorrhage 1, and refers to adrenal gland thickening and peri-adrenal fat stranding on imaging, which are nonspecific findings. However, more research is needed to elucidate this entity.
A possible explanation for adrena...
Primary adrenal cortical carcinoma (also known as adrenocortical carcinoma) is a highly malignant but rare neoplasm. It may present as a hormonally active or an inactive tumor.
Although men and women are affected equally, functioning tumors are more common in females, who are als...
Adrenal cysts are rare lesions that are usually found incidentally on imaging performed for other reasons.
Adrenal cysts are reported to be rare with an incidence of <1% 1.
Patients can present with pain or swelling, although a significant portion (~40%) ...
The adrenal (suprarenal) glands (often shortened to just the adrenals) are paired organs of the endocrine system, often asymmetric in shape.
Each gland is enclosed in the perirenal fascia and each has a body and two limbs: a medial limb and a lateral limb. However, the right adr...
Adrenal gland trauma most commonly results from blunt force trauma.
Adrenal gland trauma is present on 1-2% of CT imaging in blunt trauma although the occurrence is thought to be much higher as injury has been demonstrated at 28% in one autopsy series 1-4.
The right adrenal glan...
Despite its small size, the adrenal gland is affected by a relatively large number of neoplastic entities:
adrenal cortical carcinoma
adrenal lesions: for a more general list of...
Adrenal hemangiomas are rare benign tumors that are usually incidentally identified (one example of an adrenal incidentaloma). Its significance mainly relates to the difficulty in differentiation from other malignant lesions.
Although these can be found at any age, they are most ...
Adrenal hemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal hemorrhage can lead to catastrophic adrenal insufficiency.
The large majority of patients with unilateral adr...
Adrenal hyperplasia refers to non-malignant growth (enlargement) of the adrenal glands and is a rare cause of ACTH-independent Cushing syndrome, with unilateral adrenal cortical adenomas being the commonest. Approximately 20% of Conn syndrome cases are secondary to adrenal hyperplasia. In diffus...
Adrenal insufficiency refers to inadequate secretion of corticosteroids (glucocorticoids and mineralocorticoids).
It may occur from partial or complete destruction of the adrenal cortex, in which case it is termed primary adrenal insufficiency (also known as Addison disease). Secon...
Adrenal lesions cover a broad spectrum from benign to neoplastic entities. Due to increased use of cross-sectional imaging they are frequently detected as incidental lesions (incidentalomas). If found incidentally, please refer to the Management of Incidental Adrenal Masses: American College of ...
Adrenal lymphangiomas, also known as cystic adrenal lymphangiomas, are rare, benign cystic adrenal lesions.
Adrenal lymphangiomas are extremely rare; prevalence is estimated at 0.06% 8. They can occur at any age, with a peak incidence between the 3rd and 6th decades of life. Accor...
Adrenal metastases are the most common malignant lesions involving the adrenal gland. Metastases are usually bilateral but may also be unilateral. Unilateral involvement is more prevalent on the left side (ratio of 1.5:1).
They are present at autopsy in up to 27% of patients with ...
Adrenal myelolipomas are rare, benign and usually asymptomatic tumors of the adrenal gland characterized by the predominance of mature adipocytes.
On imaging, they usually present as large masses with a variable amount of fat-containing components.
Rare tumors with estimated aut...
Adrenal pseudocysts account for ~40% of adrenal cysts and are more likely than simple adrenal cysts to be symptomatic.
Pseudocysts do not have an epithelial lining and typically arise after an episode of adrenal hemorrhage. There is an ~7% association with malignancy (e.g. from hemor...
Tuberculous adrenalitis is the result of adrenal mycobacterium tuberculosis (TB) infection. Its incidence has decreased in the western world with the declining incidence of tuberculosis.
As the tuberculous infection causes destruction of the adrenal cortex, primary adrenal insufficie...
Adrenal vein sampling (AVS) is a procedure where blood is collected from the adrenal veins via catheter to confirm autonomous hormone production, if it is unilateral or bilateral, and to guide further treatment.
Adrenal vein sampling is commonly performed in primary aldosteronism, b...
Adrenal washout can be calculated using the density value of an adrenal mass on non-enhanced, portal venous phase and 15 minutes delayed CT scans (density measured in Hounsfield units (HU)). It is primarily used to diagnose adrenal adenoma.
[(HUportal venous phase) - (HUdelaye...
Adrenocorticotropin independent macronodular adrenocortical hyperplasia (AIMAH) is considered a rare form of macronodular adrenal hyperplasia. It is an uncommon cause of primary adrenal hypercortisolism.
Patients with AIMAH tend to present 10 years earlier on average than...
Adult cystic renal disease comprises multiple distinct hereditary and non-hereditary disease processes.
adult polycystic kidney disease (APCKD), a.k.a. autosomal dominant polycystic kidney disease (ADPCKD)
medullary cystic kidney disease
von Hippel-Lindau dis...
Alagille syndrome (also known as arteriohepatic dysplasia) is a congenital genetic multisystem disorder.
Infants typically present with symptoms relating to the liver where it is one of the most common causes of hereditary cholestasis.
Alagille syndrome is inhe...
Alport syndrome is an X-linked dominant disease characterized by progressive sensorineural hearing loss, renal disease and, at times, ocular lesions.
sensorineural hearing loss: typically high frequency 2
anterior lenticonus: most common ...
The anal triangle forms the posterior half of the diamond-shaped perineum. The triangle's three corners are defined by the tip of the coccyx posteriorly and both ischial tuberosities anterolaterally. The anterior border is the transverse perineal muscles and the posterolateral borders are the sa...
The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists.
Head and neck anatomy
Abdominal and pelvic anatomy
Androgen deprivation therapy (ADT), also called androgen suppression therapy or is a form of treatment in prostate cancer, which basically aims to slow prostate cancer growth by blocking the effect of androgens e.g. testosterone.
Such therapy is mainly used for treating men with intermediate- a...
Androgen insensitivity syndrome (AIS), also known as the testicular feminization syndrome, results from end-organ resistance to androgens, particularly testosterone. AIS may be complete or incomplete with variable imaging findings.
The incidence may vary depending on whether it i...
Angiomyofibroblastoma-like tumor of the scrotum is a rare, well-defined, slow growing mesenchymal extratesticular nonepididymal tumor rarely seen in the perineum or scrotum of older male patients. A similar tumor can occur in females in the vulval region.
In males, they are seen ...
Angiomyolipomas (AMLs) refer to hamartomatous lesions composed of abnormal, thick-walled vessels (angio-) and varying amounts of smooth muscle–like cells (-myo-) and adipose tissue (-lipoma). They predominantly occur in the kidney (renal angiomyolipoma) but occasionally occur in other organs suc...
Angiotensin converting enzyme (ACE) is a central component of the renin-angiotensin system (RAS) which assists in blood pressure control by regulating the volume of fluids in the body.
Normal individuals may have a small volume of the angiotensin converting enzyme circulating in their blood.
The angular interface sign is used to characterize an exophytic renal mass, in which the exophytic renal mass has an angular interface with the renal parenchyma. In other words, the exophytic lesion has a tapered pyramidal contour or definite apex within the renal parenchyma.
Due to its high se...
Antegrade ureteric stents are performed under fluoroscopic guidance, typically by an interventional radiologist or urologist. It is performed via percutaneous access from the kidney. It is usually performed using the access from a prior percutaneous nephrostomy, a so-called two-step procedure, a...
The anterior pararenal space is the portion of the retroperitoneum that lies between the posterior surface of the parietal peritoneum and the anterior reflection of the perirenal fascia.
It contains the duodenum (D2 and D4), pancreas and retroperitoneal segments of the ascending ...
Antopol-Goldman lesions are very rare presentations of subepithelial hemorrhage in the renal pelvis, presenting as discrete mass-like hematomas.
The cause of these lesions is uncertain, although long-term anticoagulation, non-steroidal anti-inflammatory drugs (NSAIDs) overuse, trauma...
Artificial urethral sphincters, also known as inflatable artificial sphincters and urinary control systems, are devices used for the treatment of urinary stress incontinence (e.g. due to pelvic floor dysfunction in female or prostate surgery in male) and are sometimes used in combination with a ...
Asbestos-related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibers. They can be divided into benign and malignant processes 1-3.
Benign pleural and parenchymal lung disease
asbestos-related benign pleural...
Ascites (hydroperitoneum is a rare synonym) is defined as an abnormal amount of intraperitoneal fluid.
Ascites (plural is same word) tends to be reserved for relatively sizable amounts of peritoneal fluid. The amount has not been defined formally, however it is noted that physiolog...
Atresia (plural: atresias) refers to a situation where there is absence, underdevelopment or abnormal closure, of a normal anatomical tubular structure or opening.
Contrast this with agenesis which refers to the complete absence of any anatomical structure including its primordial precursors.
Atypical small acinar proliferations (ASAP) are premalignant lesions of the prostate, which can be found in as many as 5% of prostate biopsies. They are suspicious glands without adequate histologic atypia to establish a definitive diagnosis of prostate cancer. Some studies showed that there is ...
The aubergine sign (also known as egg-plant sign or deformity) is a clinical sign of a fractured penis. Hemorrhage beyond the tunica albuginea produces swelling and bruising of the penis simulating the appearance of an aubergine.
Autonephrectomy refers to the end stage of renal tuberculosis where chronic tuberculous infection causes caseous necrosis and progressive renal cavitation, rendering the kidney non-functioning 1.
It is a rare occurrence in non-endemic populations today but can be misdiagnosed if n...
Autosomal dominant polycystic kidney disease (ADPKD), also sometimes more vaguely referred to as "adult polycystic kidney disease", is as the name would suggest, a hereditary form of adult cystic renal disease.
Autosomal dominant polycystic kidney disease is one of the most commo...
Autosomal recessive polycystic kidney disease (ARPKD) is one of many pediatric cystic renal diseases.
On imaging, it usually presents on ultrasound with enlarged echogenic kidneys with multiple small cysts. Liver involvement with coarse echotexture, biliary tract cystic changes, and portal hype...
The avascular plane of Brodel is the section of renal parenchyma between 2/3 anterior and 1/3 posterior kidney on the cross-section that is relatively avascular. The reason for its relative avascularity is that it represents the plane where the anterior and posterior segmental renal artery branc...
Azoospermia refers to complete absence of sperm in the semen. It accounts for 5-10% of male infertility 1.
It can be obstructive or non-obstructive, e.g. primary testicular failure. This differentiation is of utmost importance, as obstructive azoospermia can be corrected by surgical ...
Bähren classification of left varicoceles:
type 0: no evidence of venous reflux in internal spermatic vein (ISV)
type I: single ISV with insufficient or absent valve
type II: single ISV with ≥ 2 ostia to renal vein; may be branches to ascending lumbar/retroperitoneal veins
IIa: insufficient ...
Balkan nephropathy (a.k.a. Balkan endemic nephropathy) refers to a degenerative interstitial nephropathy endemic to the Balkan states, which is associated with a very high rate of transitional cell carcinomas of the renal pelvis and upper ureter.
The condition is largely restricte...
The ball-on-tee sign, golf ball-on-tee sign, or egg in cup appearance, refers to a urographic pattern of papillary excavation that may be seen with renal papillary necrosis.
The sign occurs when contrast material fills central excavations in the papilla of the interpolar region giving a ball-on...
The balloon on a string sign refers to the appearance of the ureter on intravenous urography in ureteropelvic junction obstruction. It is seen due to the high and eccentric point of the exit of ureter from a dilated renal pelvis.
Bardet-Biedl syndrome (BBS), previously known as the Laurence-Moon-Bardet-Biedl syndrome (LMBBS), is a rare autosomal recessive hereditary condition.
The clinical spectrum includes:
retinal anomalies: similar to that of retinitis pigmentosa
Bartholin gland cysts (often shortened to Bartholin cysts) are cysts of the Bartholin gland, found in the posterolateral inferior third of the vagina and are associated with the labia majora.
Most patients are asymptomatic 4.
infection: may turn into Barth...
The Bartholin glands, also known as the greater vestibular glands (or vulvovaginal glands) are paired pea-sized structures, lying on either side of the vaginal opening, and are homologous to the bulbourethral (Cowper) glands in the male. They form part of the vulva.
These glands ...
Bartter syndrome is a rare inherited renal disorder.
Bartter syndrome is characterized by hyperplasia of the juxtaglomerular cells along with:
elevated plasma renin
Basal cell carcinoma of the prostate or prostatic adenoid basal proliferation of uncertain significance is a type of prostate cancer resembling adenoid cystic carcinoma of the salivary glands.
Other terms include 'adenoid cystic carcinoma', 'adenoid basal cell tumor', 'adenoid cyst...
Batson venous plexus, also known as Batson veins, are a network of veins with no valves that connect deep pelvic veins draining the bladder, prostate, and rectum to the internal vertebral venous plexus 1. These veins are important because they are believed to provide a route for spread of pelvic...
The bear paw sign refers to the cross-sectional appearance of the kidney affected by xanthogranulomatous pyelonephritis. There is a radial arrangement of multiple, low attenuation rounded spaces representing dilated calyces, surrounded by thin renal parenchyma that has higher attenuation or cont...
Behçet disease is a multisystemic and chronic inflammatory vasculitis of unknown etiology.
The mean age at which Behçet disease occurs is 20-30 years. The disease is most prevalent in the Mediterranean region, Middle East and East Asia. The highest incidence has been reported in T...
A bell clapper deformity is a predisposing factor in testicular torsion in which the tunica vaginalis has an abnormally high attachment to the spermatic cord, leaving the testis free to rotate. Bell clapper deformity predisposes to intravaginal torsion of the testis.
It is best defined as the c...
Benign prostatic hyperplasia (BPH), also known as benign prostatic enlargement (BPE), is an extremely common condition in elderly men and is a major cause of bladder outflow obstruction.
The term benign prostatic hypertrophy was formerly used for this condition, but since there is...
A bifid ureter, or ureter fissus, is an example of incomplete duplication of a duplex collecting system and is an anatomical variant.
Multiple seemingly unrelated terms for blind-ending bifid ureters are currently in use and there is no consensus on terminology in the literature. T...
The differential for bilaterally enlarged adrenal glands (adrenomegaly) is relatively limited:
micronodular adrenal hyperplasia
macronodular adrenal hyperplasia
adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH) 2
Bilateral renal enlargement can arise from a number of causes which include 1,2:
diabetic nephropathy (common)
renal involvement with lymphoma
acute interstitial nephritis
acute urate nephropathy
Bilateral testicular lesions have a relatively limited differential diagnosis.
lymphoblastic leukemia (acute or chronic)
primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Bilobed testis, also known as incomplete unilateral polyorchidism, is a very rare congenital variant in children, and considered to be an incomplete form of polyorchidism.
Birt-Hogg-Dubé syndrome or folliculin gene-associated syndrome is a genetic multisystemic disease mainly characterized by:
multiple lung cysts and secondary spontaneous pneumothoraces
multiple bilateral renal tumors (particularly chromophobe renal cell cancer and oncocytoma)
Bladder and ureteric tuberculosis (TB) refers to infection of ureters and urinary bladder with Mycobacterium tuberculosis.
characteristic beaded appearance due to alternate areas of strictures and dilatation (chronic state)
A simple mnemonic to recall the common causes of bladder calcification is:
C: cytotoxic: see radiation- and chemotherapy-induced cystitis
R: radiation: see radiation- and chemotherapy-induced cystitis
I: interstitial cystitis