Diagram displaying a left ureterocele.
Ureteroceles are classified as either intravesical or ectopic. In an intravesical ureterocele, which is also known as a simple ureterocele, the orifice of the ureter and the ureterocele itself are intravesical. The ectopic ureterocele lies in the submucosa of the bladder, and some part of it may extend into the bladder neck or urethra.

Intravesical ureteroceles can be unilateral or bilateral. They are usually diagnosed in adults; hence, they are also called adult-type ureteroceles. They occur more often in women than in men. Ureteroceles are considered congenital by some authorities. Because one of the causes is a narrowed ureteral orifice, however, it is reasonable to conclude that not all unilateral ureteroceles are congenital. Inflammation or trauma leading to fibrosis can cause development of such a ureterocele. Most intravesical ureteroceles are incidental findings in asymptomatic adult patients. When large, ureteroceles can cause obstruction of the bladder neck, along with obstruction of the ipsilateral ureter. This results in an increased frequency of calculus formation, as well as infection. With obstruction, there may be substantial delay in filling the ureter, requiring delayed imaging to make the diagnosis.

Ectopic ureteroceles are almost always seen in association with duplex ureters and arise from the upper-pole ureter. Ureteroceles are usually diagnosed in childhood. Rarely, an ectopic ureterocele occurs without ureteral duplication, usually in boys. Most commonly, the orifice is stenotic, resulting in an obstructed and often nonfunctioning system. An ectopic ureterocele generally appears as an intravesical filling defect instead of the classic cobra head sign.

The cobra head sign is an indicator of an un-complicated ureterocele. However, a cobra-shaped distal end of a ureter may be seen with incomplete distal ureteral obstruction caused by a tumor or calculus. This appearance is termed pseudoureterocele. The appearance of the radiolucent wall surrounding the dilated distal ureteral segment is an important differentiating point between a ureterocele and a pseudoureterocele. The lucency or halo surrounding a pseudoureterocele is thicker than that of a uterocele and is poorly defined; in cases of tumors, it may be irregular and may show a filling defect within the ureterocele. The urographic diagnosis of a pseudoureterocele is much more likely than that of a ureterocele when there is asymmetry of the dilated ureteral lumen, moderate to severe obstruction of the upper tract, and evidence of an acquired cause, such as a calculus or abnormal vesical mucosal pattern. Rarely, thickening of this lucency in a patient with a known ureterocele is usually associated with a complicating process, such as edema with a calculus.

Ultrasonography may demonstrate the wall of the ureterocele projecting into the lumen of the bladder. In questionable cases, cystoscopy may be helpful to rule out a bladder tumor that has formed a pseudoureterocele.  

The Ivory Vertebra Sign

The ivory vertebra sign is seen at conventional radiography and refers to an increase in opacity of a vertebral body that retains its size and contours, with no change in the opacity and size of adjacent intervertebral disks. The increased opacity may be diffuse and homogeneous and involve most or all of the vertebral body, giving it a white appearance as opposed to the normal or possibly osteoporotic appearance of the rest of the vertebral column.

The radiologic finding of a “white” vertebral body is observed in various conditions, each with its own mechanism of producing the classic appearance of the ivory vertebra sign. Osteoblastic metastases elicit a sclerotic response. This stimulation of osteoblasts results in the patchy replacement of vertebral body spongiosa with dense and amorphous bony mass that may become confluent. In a similar manner, certain lymphomatous deposits elicit marked osteoblastic response in the spongiosa, thereby resulting in bone formation and diffuse homogeneous sclerotic change. These lymphomatous foci involve the vertebral body through either hematogenous spread or contiguous invasion from adjacent lymph nodes. Another explanation is Paget disease, a condition in which simultaneous atrophy of the spongiosa and coursening of the vertical trabeculae can simulate an ivory vertebra.

Paget disease, however, usually causes expansion of the vertebral body contour, thereby limiting the ability of a vertebra affected by Paget disease to fully conform to the definition of an ivory vertebra. Reactive bone formation that occurs in response to stress on weakened bone, similar to the way a callus develops in a healing fracture, can give the appearance of an ivory vertebra; this process is termed idiopathic segmental sclerosis.

The ivory vertebra sign can be seen in both adults and children. In children, the finding is much less common and is typically the result of lymphoma, usually Hodgkin lymphoma. Even less frequently, children may have osteosarcoma, metastatic neuroblastoma, medulloblastoma, or osteoblastoma that involves a vertebral body and causes increased opacity. A few cases of Ewing sarcoma with dense vertebral bodies have been reported. In such cases, while the tumor itself is lytic, the reactive bone formation can be exceptionally opaque.

In adults, numerous conditions are responsible for the appearance of an ivory vertebra. Traditionally, the ivory vertebra sign has been associated with metastatic disease, especially carcinoma of the prostate or breast, and occasionally with osteosarcoma, carcinoid, Paget disease, and lymphoma, particularly Hodgkin lymphoma.

Carcinoma of the breast or prostate commonly results in osteoblastic metastases. A radiopaque vertebral body at one or more vertebral levels in an elderly man is most compatible with a diagnosis of metastatic disease, commonly as the result of prostate carcinoma. Other metastatic tumors, including lymphoma, must be considered along with more rare lesions, such as plasmacytoma, chordoma, or primary bone sarcomas. Metastatic cancer involving the spine usually manifests at several vertebral levels; however, solitary lesions in patients with breast carcinoma are not uncommon.

Lateral radiograph shows uniformly increased opacity of entire T7 vertebra (arrow), with retention of vertebral body size and contour. Incidental note is made of loss of height at T8 vertebra.

Transverse computed tomographic scan at level of T7 vertebra demonstrates increased opacity involving nearly the entire vertebral body.                       

Paget disease can give the appearance of an ivory vertebral body, but, more often, the disease is characterized by the “picture frame” vertebral body. The “picture frame,” “double contour,” or “windowed” vertebral body of Paget disease shows increased overall opacity, with sclerosis most marked at the periphery, and a relatively lucent center owing to atrophy of the spongiosa. The trabecular bone is thickened, and increased anteroposterior and lateral dimensions result in overall bone expansion. In Paget disease, the increased size of the vertebral body is a distinct appearance and usually allows differentiation of this disease from the other causes of the ivory vertebra sign.

Paget disease occurs in an older age group and is usually polyostotic. It has been suggested that idiopathic ivory vertebra, which is defined as an ivory vertebra for which no apparent cause is found and for which the appearance remains unchanged over time, may be attributable to asymptomatic Paget disease of bone. Definitive histologic evidence of the condition, however, is lacking.

Osteomyelitis is known to produce sclerosis in a vertebra during the healing phase, but this condition rarely involves a single vertebra. Usually, erosive change is present at the margins of the intervertebral disk and helps to guide diagnosis.

The ivory vertebra sign has numerous causes. While clinical settings will vary, and a list of causes is available, most causes of the ivory vertebra sign are rare. In adults, three conditions should generally be considered: metastatic cancer, Paget disease, and lymphoma.                      


The Rugger Jersey Spine Sign

Rugby Sweater.

At radiography, sclerotic bands along the superior and inferior thoracic and lumbar vertebral body endplates give a striped appearance to the vertebral bodies, with a relative band of lucency at the center of each vertebral body. The alternating parallel sclerotic and lucent bands are analogous to the stripes on an English rugby sweater, from which arises the name “rugger jersey spine”.

The opaque sclerotic bands seen on the inferior and superior endplates of vertebral bodies represent accumulations of excess osteoid. Although they are deficiently mineralized, the areas of osteoid appear opaque at radiography because of their increased volume in comparison with that of normal bone. The spinal canal and intervertebral disk spaces are normal.

Lateral radiograph of the thoracic spine in a patient with chronic renal failure. The image shows band-like regions of increased opacity at the superior and inferior margins of the vertebral bodies, which is typical of the rugger jersey spine sign.                       

The rugger jersey spine sign is said to be almost DIAGNOSTIC OF the osteosclerosis associated with secondary hyperparathyroidism of chronic renal failure. The major skeletal components of renal osteodystrophy that can be seen on radiographs include osteomalacia, osteosclerosis, and soft-tissue calcification. Osteomalacia is defined as bone that contains insufficient or delayed mineralization of osteoid tissue. In children, osteomalacia secondary to renal disease may manifest as rickets. In adults, osteomalacia as a result of renal osteodystrophy may manifest as osteopenia, a decrease in bone density. Renal osteodystrophy may manifest radiographically as subperiosteal resorption of bone in the radial aspect of the middle phalanges of the hand. This process later manifests radiographically as areas of resorption in concave areas such as the proximal tibia and femoral neck. In contrast, osteosclerosis due to renal osteodystrophy tends to predominate in the axial skeleton, most commonly manifesting in the pelvis, ribs, and spine. Osteosclerosis occurs in about 20% of patients with chronic uremia and renal osteodystrophy. 

Renal transplantation paradoxically worsens osteodystrophy, and steroids necessary to prevent transplant rejection accentuate osteoporosis and can cause ischemic necrosis of the femoral heads. In addition, secondary hyperparathyroidism can continue after renal transplantation. Tertiary hyperparathyroidism may develop, an entity in which the parathyroid glands develop autonomous control, which results in persistent bone resorption and hypercalcemia. 

Other disease processes may mimic the rugger jersey spine sign. Paget disease, osteoporosis, metastatic lesions, or osteomalacia are the diseases that have radiographic appearances that are commonly confused with the rugger jersey spine.

One factor to keep in mind when differentiating spinal dystrophic findings is that the rugger jersey spine sign is multi-segmental, as it affects multiple vertebral bodies. The bands of increased opacity along the superior and inferior aspect of the vertebral bodies differ from the uniformly increased opacity seen in Paget disease, skeletal metastasis, or lymphoma. Skeletal metastasis and lymphoma produce the so-called ivory vertebral body, and these diseases may affect a solitary vertebral body.

The rugger jersery spine sign can be differentiated from the “picture frame” vertebral body seen with Paget disease. The cortex of the vertebral body is thickened in a patient with Paget disease. This is a result of disorganized new cortical bone formation after excessive osteoclastic activity causes the resorption of normal bone. At radiography, this results in increased opacity of the cortex on ALL sides of the vertebral body, whereas the characteristic sclerosis of the rugger jersey spine is seen only at the superior and inferior endplates. 

Lateral radiograph of the lower thoracic and lumber spine in a patient with Paget disease showing the "frame picture".
The appearance of osteoporotic vertebral bodies can vary and at times may mimic that of osteosclerosis. Osteoporosis most frequently results in wedging and compression of the vertebral bodies. Osteoporosis can result in concavity of the superior and inferior endplates. These appearances are caused by diffuse weakening of the bone and occur most commonly in the thoracic and lumbar spine. Trabecular thinning, which is usually seen in the middle to upper thoracic spine, leads to relative radiographic opacity of the superior and inferior endplates. 

Other generalized disease processes that seemingly imitate the rugger jersey spine sign include fluorosis and myelofibrosis. Fluorosis and myelofibrosis involve the axial skeleton and result in increased opacity of the vertebral bodies, pelvis, and bones of the thorax. Diffuse findings such as ligamentous calcification, periostitis, and vertebral osteophytosis differentiate fluorosis from renal osteodystrophy. Myelofibrosis is associated with splenomegaly and cortical thinning of long bones. A complete skeletal survey, in addition to pertinent clinical and laboratory data, aids in distinguishing these disorders.

The Football Sign

American Football with laces and seams.

The football sign, which is seen on supine abdominal radiographs, refers to a large oval radiolucency in the shape of an American football. The long axis of the “football” runs cephalocaudad, and the blunted ends are defined by the diaphragm and pelvic floor. A well-defined and vertically oriented linear opacity may be identified within the cephalic portion of the radiolucency, overlying the right upper abdomen. An additional, well-defined and vertically oriented linear opacity may be seen within the caudal portion of the radiolucency, overlying the midline of the lower abdomen.  

The oval radiolucency seen in the football sign represents massive pneumoperitoneum, which distends the peritoneal cavity. In the supine position, free air collects anterior to the abdominal viscera, producing a sharp interface with the parietal peritoneum and thereby creating the football outline. The pneumoperitoneum may outline the falciform ligament, which is seen as a faint linear opacity situated longitudinally within the right upper abdomen.
Also, the massive pneumoperitoneum may outline the median umbilical ligament, which comprises the urachal vestige, or may outline the medial and lateral umbilical ligaments, which comprise the umbilical arteries and inferior epigastric vessels, respectively. Similar to the appearance of the falciform ligament, these anterior abdominal body wall structures may be visualized as faint longitudinal linear opacities in the midline of the lower abdomen. Some authors describe these anterior abdominal wall structures as necessary components of the football sign; they represent the seams or laces of an American football.

Anteroposterior supine abdominal radiograph shows the football sign in a neonate with rectal perforation secondary to traumatic placement of a rectal tube. Pneumoperitoneum is seen as a large oval radiolucency demarcated by the parietal peritoneum of the abdominal wall (curved arrows). The falciform ligament (straight arrows) is outlined by air.                       
Conditions that result in a degree of pneumoperitoneum sufficient to create the football sign occur most commonly in infants. Massive pneumoperitoneum is much less common in adults and older children. In part, this may relate to the improved ability of older patients to communicate their abdominal symptoms, which leads to earlier intervention. A small-to-moderate volume of pneumoperitoneum in an adult may be inadequate to produce the football sign, but this may represent a relatively large amount of free air in a small infant.

Although the source of pneumoperitoneum may vary, the football sign is most frequently encountered in infants with spontaneous or iatrogenic gastric perforation. In many cases of perforated small bowel or perforating appendicitis, there is little to no pneumoperitoneum identified, which is likely because of the localized inflammatory process surrounding the perforation.

Other causes of pneumoperitoneum in neonates include necrotizing enterocolitis, bowel obstruction (i.e. malrotation with midgut volvulus, Hirschsprung disease, meconium ileus, or atresia), and sources of inflammation such as gastric or duodenal ulcers. Mechanical ventilation causing barotrauma and extra-ventilatory air can extend beneath the diaphragm, resulting in pneumoperitoneum without gastrointestinal perforation.

In most cases, the football sign in infants is DIAGNOSTIC of gastrointestinal perforation, and NO further imaging is necessary. With smaller quantities of extraluminal air, the football sign may be absent, and other features, such as air on both sides of the bowel wall or localized radiolucency, may be seen. Either left lateral decubital or cross-table lateral views are standard in assessment for pneumoperitoneum.

The football sign, seen at supine abdominal radiography, refers to a large oval radiolucency that represents a large amount of pneumoperitoneum in the shape of an American football. The ovoid appearance is the acknowledged hallmark of the football sign. Ancillary findings, including visualization of the falciform ligament or the umbilical ligaments, are also confirmatory of pneumoperitoneum and have been variously included in descriptions of this sign.                   

The Dripping Candle Wax Sign

Dripping Candle Wax.
The dripping (or flowing) candle wax sign is seen on conventional radiographs depicting bone. The appearance is that of irregular cortical hyperostosis, typically occurring on one side of the involved bone, and has been likened to melted wax flowing down one side of a candle.

The dripping candle wax sign indicates melorheostosis. The radiographic findings may reflect a developmental error primarily in intramembranous bone formation. This leads to an irregular thickening of cortical bone (cortical hyperostosis) that extends up to (but usually not past) the articular surface. Pathologic findings suggest both overproduction of bone matrix and increased angiogenesis. The distribution of affected bone is thought to be due to the predilection of melorheostosis to occur in sclerotomes (skeletal regions innervated by a single spinal sensory nerve).

Preoperative posteroanterior chest radiograph of a man presenting for excision of facial arteriovenous malformation.
Note irregular flowing hyperostosis (arrows) along caudal surface of the eighth and ninth right posterior ribs.                       

Melorheostosis (also known as Leri disease) is a rare sclerosing bone dysplasia. The name is derived from the Greek words for limb (melos) and flow (rhein), due to its characteristic appearance of flowing hyperostosis. Patients are often asymptomatic, with the condition diagnosed as an incidental finding on radiographs obtained for another purpose.

When melorheostosis does manifest clinically, the most common presentation is of limb stiffness or pain. Although the age at presentation varies, it usually remains occult until late adolescence or early adulthood. The disease follows a chronic progressive course, occasionally resulting in substantial disability that may lead to amputation.

Melorheostosis predominantly affects the appendicular skeleton and is most common in the long bones of the upper and lower extremities, although it can be seen in the hands and feet as well. Melorheostosis has rarely been reported in the axial skeleton. It may affect a single bone (monostotic), a single limb (monomelic), or multiple bones (polyostotic).

The dripping candle wax sign on conventional radiographs indicates melorheostosis. Although other imaging techniques are rarely necessary for diagnosis, similar findings can be noted on computed tomographic (CT) scans. Magnetic resonance imaging depicts decreased signal intensity of affected bone on images obtained with all pulse sequences, while radionuclide bone scanning reveals moderate and asymmetric increased uptake.

Non-contiguous transverse CT images through eighth (left image) and ninth (right image) right posterior ribs of same patinet with previous plain chest X-ary show sharp delineation between normal and affected bone segments (arrows), highlighting sclerotomal distribution.


Ludwig’s Angina

Ludwig’s angina denotes cellulitis of the floor of the mouth with infection of the submental, sublingual, and submandibular space. This infection is usually due to streptococcus or staphylococcus species. Patients usually present with pain, tenderness and swelling of the mouth floor. The infection is usually precipitated by an odontogenic infection. In neglected cases, Ludwig’s angina may spread inferiorly through fascial planes into the mediastinum, with some patients presenting with chest pain. Since the tongue can rapidly become posteriorly displaced in this condition, securing a patient’s airway is a priority.

Contrast-enhanced CT shows swelling of the floor of the mouth frequently associated with streaky changes in the adjacent subcutaneous fat and thickening of the overlying platysmus muscle. Enlargement of the submental or submandibular lymph nodes may also be seen, with pus or gas formation present in late cases.

Ludwig’s angina. Contrast enhanced CT shows multiple abscess (arrow) in the sublingual space.
Contrast enhanced MR images, if performed, may show a thickened floor of the mouth with strong enhancement. On T2-weighted images, diffuse high signals are evident in the floor of the mouth and adjacent soft tissues.

Parapharyngeal Abscess

An abscess in the parapharyngeal space may arise from direct extension of infection from the pharynx through the pharyngeal wall, as a consequence of odontogenic infection, local trauma, and occasionally peritonsillar abscess. Diabetes is the most common systemic condition predisposing one to parapharyngeal abscess.

Patients often present with fever, sore throat and neck swelling. Erythema, odynophagia, and dysphagia often accompany such infections. Trismus is most commonly associated with anterior compartment abscesses.

Parapharyngeal space abscess. Contrast-enhanced CT shows a low attenuation fluid collection with peripheral enhancement in the left parapharyngeal space (arrow).
Contrast-enhanced CT scanning is the imaging examination of choice to diagnose parapharyngeal abscess. CT shows a single or multiloculated low-density lesion with an air and/or fluid center with occasional enhancement of the abscess wall.

Rasmussen's Encephalitis MRI Findings

Rasmussen encephalitis is a chronic, progressive inflammation of the brain of un-known origin. The onset is in childhood and is characterized by an abrupt appearance of focal, persistent motor seizure activity (epilepsia partialis continua), followed by hemiplegia and progressive cognitive deterioration. Early diagnosis and treatment with immunoactive agents or hemispherectomy are sought to prevent the cognitive decline. A hypothesis of the pathogenesis is glutamate receptor autoimmunity associated with persistent viral infection. This receptor activation may trigger seizures in these patients.

CT and MRI Images of All patients display cortical atrophy associated with ipsilateral ventricular enlargement and caudate atrophy, more severe in those with hemiparesis. The most affected areas were insular, temporal and parietal regions. Gray and white matter focal signal intensity abnormalities (hyperintense signal in long TR-weighted images) were found in with hemiparesis.

Histopathologic examination of biopsy material reveals a characteristic triad of findings: perivascular lymphocytic cuffing of round cells, gliosis and microglial nodules. CT and MRI demonstrate progressive destruction of a single cerebral hemisphere. Decreased NAA and elevation of glutamate/glutamine levels on MRS are reported.

MRS performed showed increased lactate and choline and decreased NAA in atrophic regions in a patient with Rasmussen's Encephalitis.

Bezold Abscess

A Bezold abscess is a rare complication of otomastoiditis with necrosis of the mastoid tip and spread of infection from bone to the adjacent soft tissue. Inflammatory collections may course along the plane of the sternocleidomastoid muscle to the lower neck. If left untreated, the abscess may spread as far as the larynx and mediastinum, which results in a poor prognosis. Clinically, patients present with fever, neck pain, restricted neck motion, and otalgia. Due to the close proximity to the internal jugular vein, internal jugular vein thrombosis is a recognised commonly associated complication.
On CT imaging, there is usually unilateral opacification of the middle ear and mastoid cavities, often associated with bone erosion, especially of the mastoid tip. The abscess involves the adjacent musculature surrounding the mastoid and extends inferiorly.

A: Axial contrast-enhanced CT shows opacification of the mastoid air cells with associated bone erosion indicating an aggressive inflammatory process (arrow).
B: The soft tissue algorithm demonstrates a multiloculated abscess involving the paraspinal musculature (arrow).

MRI of the head showed subcutaneous and occipital epidural abscesses. On magnetic resonance angiography, intracranial thrombosis was found in both the right transverse sinus and the sigmoid sinus.
MRI demonstrates a right suboccipital epidural abscess (circled area).
Magnetic resonance angiogram demonstrating thrombosis of the transverse and sigmoid sinuses (circled area).