Weber B ankle fracture

This is a trans-syndesmotic fracture with usually partial - and less commonly, total - rupture of the syndesmosis. According to Lauge-Hansen, it is the result of an exorotation force on the supinated foot.

The fracture starts anteriorly at the level of the ankle joint and extends in a posterior and proximal direction.

• Stage 1 - Rupture of the anterior syndesmosis.
• Stage 2 - Oblique fracture of the fibula (this is the true Weber B fracture).
• Stage 3 - Rupture of the posterior syndesmosis  or - fracture of the malleolus tertius.
• Stage 4 - Avulsion of the medial malleolus or - rupture of the medial collateral bands.

Smith’s fracture

● Fall onto the dorsum of the hand or due to a direct blow.
● Patient presents with a swollen tender wrist with associated deformity.
● Often described as a reverse Colles’ fracture.
● AP and lateral views recommended as may appear similar to Colles’ fracture if an AP view alone is examined.
● Transverse fracture through the distal radial metaphysis with associated
volar angulation and volar shift.
● Look for median nerve symptoms.

Oesophageal perforation/rupture

● Classically described following a forceful vomiting (Boerhaave syndrome).
● Commoner causes include – iatrogenic trauma, blunt/penetrating trauma, chemical injury, foreign body perforation, spontaneous rupture and postoperative breakdown.
● The oesophagus has no serosal covering and hence perforation allows direct access to the mediastinum.
● Perforation of the upper/cervical oesophagus allows access to the retropharygeal space.
● Perforation of the lower/mid-oesophagus tends to directly enter the mediastinum. Inflammatory reaction causes contamination of the pleural space.This is facilitated by negative pleural pressure.

● CXR: Classic signs are subcutaneous emphysema, pneumomediastinum, left sided pleural effusion, hydropneumothorax and mediastinal widening.
● Cervical spine: Lateral views may reveal retropharyngeal air.
● Pleural effusions, pulmonary infiltrates and a true mediastinal air–fluid level are not typically seen with a spontaneous pneumomediastinum.
● Water soluble contrast studies are of benefit to demonstrate perforations. If no perforation is seen a barium swallow will show better mucosal detail.These studies can be repeated over time.

Ultrasound In Radiology

Ultrasound Machine.

Sound is propagated through a medium (e.g. air) as a mechanical vibration of the particles of that medium and in simple terms may be categorised by its loudness and pitch or frequency. “Ultra” means beyond, ultrasound is sound with a frequency beyond that of human perception (i.e. >20 kHz), and has the same physical properties as “audio” sound. Most clinical diagnostic applications of ultrasound employ frequencies in the range 2 - 10 MHz.

  

Ultrasonic energy travels through a medium in the form of a wave. Although a number of different wave modes are possible, in almost all diagnostic applications, ultrasound propagates in the form of a longitudinal wave, where the particles of the medium oscillate in the direction of propagation of the sound. Energy is transferred through the medium in a direction parallel to that of the oscillations of the particles. The particles themselves do not move through the medium. They simply vibrate to and fro about their mean position.

It is often useful to think of the source of ultrasound, the transducer, as a vibrating piston. As it moves it displaces the adjacent particles of the adjoining medium. These in turn displace more particles throughout the medium. Since the particles are not rigidly fixed to each other, they do not all move together. There is a delay between the movement of adjacent particles (analogous to a series of balls connected by springs). 

At a particular time there will be some regions where the particles are closer together and the pressure and density of the medium is increased (regions of compression) and areas where the particles are further apart and the pressure and density of the medium is decreased (regions of rarefaction). These regions of compression or rarefaction move through the medium as a wave.

Practical measures for the reduction of patient radiation dose

Radiation Sign. Please Take care.

   (A) Some dose-saving equipment:

1.  Fast screen-film combinations (e.g. rare earth)

2. Low attenuation (e.g. carbon fiber) materials for cassette fronts, antiscatter grid interspacing.

3. Constant potential generators with appropriate kilovoltage.

4. Appropriate beam filtration (minimum 2.5 mm Al for general radiography).

5.  Specialized equipment for mammography and pediatrics

6. Pulsed and frame-hold (image storage) fluoroscopy equipment.

7.  Digital radiography equipment.

8. Dose-area product meter to monitor patient exposure.

   (B) Some dose-saving techniques:

1. Use smallest possible field size and good collimation.

2. Collimate to exclude radiosensitive organs (gonads, breasts and eyes).

3. When gonads lie outside the primary beam, make distance between the edge of the field and the gonads as large as possible.

4. Shield breasts, eyes, and gonads unless the area of interest would be masked. Dose to ovary can be halved and that to testes reduced by a factor of 20.

5. Use largest practicable focus to skin distance: never less than 30 cm, especially in mobile radiography.

6. Position the patient carefully. Reduce the dose to the female breast and, in skull radiography, to the eye by postero-anterior projection. Minimize the gap between patient and film-screen.

7. Use compression of patient where possible.

8. Use non-grid techniques when examining children and small adults.

9. Keep film reject rate due to all causes down to 5%. Check the factors before exposure. Quality assurance, particularly of automatic processors, is important.

10. In fluoroscopy use the minimal field size and minimal screening time essential for good diagnosis.

11. Use zoom or small field techniques, which require a higher dose rate, with discretion.

(C) High-risk examinations:

1. Keep pediatric radiation doses to an absolute minimum consistent with adequate diagnosis as children up to the age of 10 years are believed to be 3-4 times more radiosensitive than adults.

2. In pelvimetry: use MRI or CT scanography where possible; otherwise use fast rare earth screens and carbon fiber components.

3. Mammography is not generally performed on women younger than 50 years unless there is a family history of breast cancer or the patient has related symptoms.

4. In CT scanning, take the minimum number of slices, position the patient to avoid the eyes and other critical organs; reduce milliamperage if appropriate, e.g. for the chest.

5.  Patients who are or might be pregnant.

6. Interventional radiology needs  care  to avoid  skin  reactions;  use  pulsed and frame-hold systems: minimize screening times.

The subarachnoid cisterns

Regarding the subarachnoid cisterns:

A) The chiasmatic or suprasellar cistern contains the circle of Willis.

B) The chiasmatic cistern leads posteriorly to the interpedencular cistern.

C) The cistern of the great cerebral vein is the quadrigeminal cistern.

D) The confluence of the vein of Galen and inferior sagittal sinuses occur in the quadrigeminal cistern.

E) The pericallosal artery runs in the cistern of the lamina terminalis.

Fusion Of Sacroiliac Joint

Fusion of sacroiliac joint is seen in: 

A) Tuberculosis.

B) Metastasis.

C) Reactive arthritis.

D) Reiter's.

E) Psoriasis.

ABCS In Cervical Spine Injuries

A cervical spine injury is unlikely in an alert patient (i.e. not under the influence of alcohol or drugs) without neck pain, bony tenderness, focal neurological defect or a painful distracting injury. 

Obtain lateral, AP and an open mouth peg view if a cervical spine injury 

is suspected. 

In the lateral view ABCS have to be examined as described below:

A Alignment and adequacy: 

Visualize from base of skull to the C7/T1 junction. In-line arm traction, during the cross table lateral or a swimmer’s views can be helpful in visualising C7/T1. Look for the normal smooth curve of the anterior vertebral, posterior vertebral and spino-laminar lines. In a child pseudo-subluxation of C2 on C3 can cause confusion. In these cases, examine the spinolaminar line from C1 to C3. If the bases of these spinous processes lie 2 mm from this line an injury should be suspected. Correlate with soft tissue findings.The distance between the anterior arch of C1 and the odontoid peg should be 3mm in an adult and 5mm in a child.

Lateral cervical radiography showing (A) anterior vertebral line, (P) posterior vertebral line and (SL) spinolaminar line. 

B Bone:

Assess for normal bony outline and density. An increase in density may indicate a compression fracture.

C Cartilage: 

The intervertebral spaces should be uniform. Widening of these or the interspinous distance may indicate an unstable dislocation. An increase in interspinous distance of 50% suggests ligamentous disruption. Muscular spasm can make interpretation difficult.

S Soft tissues: 

Retro-pharyngeal soft tissue swelling may be the only sign of a significant injury. Normal measurements are less than 7mm C2–C4 (half a vertebral body at this level) and less than 22m below C5 (a vertebral body width). Air within the soft tissues suggests rupture of esophagus or trachea/bronchus. Bulging of the pre-vertebral fat stripe is an early sign.

MRI for Imaging Breast Implants

MRI is the technique of choice for assessing the integrity of breast implants, with a sensitivity and specificity of over 90%. When imaging breast implants, NO contrast agent is required unless malignancy is suspected. Imaging should be performed in the prone position using a dedicated breast coil. The main goal is to determine whether the implant has ruptured and, if so, to establish the location of the leaked filler (usually silicon).

When implants fail, the rupture may be either intra-capsular or extra-capsular. Intra-capsular rupture occurs when silicon has escaped from the plastic shell of the implant, but is contained within the fibrous implant capsule; signs of intracapsular rupture include the ‘wavy line’, ‘linguini’, ‘key-hole’ and ‘salad oil’ sign. False-positive interpretations can be made when normal implant folds are mistaken for signs of rupture.

Intra-capsular implant rupture.'linguini' sign and ‘salad oil’ sign.

Extra-capsular implant rupture.

Hampton's hump sign

Picture of a camel displaying its hump which is a rounded mass or protuberance on its back.

Hampton's hump sign, also called Hampton hump, is a radiological sign which consists of a shallow wedge-shaped opacity in the periphery of the lung with its base against the pleural surface. It is named after Aubrey Otis Hampton who first described it in 1940.


Hampton's hump along with Westermark's sign aids in the diagnosis of pulmonary embolism.

Hampton's Sign.

Yellow star in the region of wedged-shape opacity that represent Hampton's Sign.  

Todani Classification Of Bile Duct Cysts

According to Todani classification of bile duct cysts, there are FIVE major classes of bile duct cysts exist (ie, types I-V), with sub-classifications for types I and IV (ie, types IA, IB and IC; types IVA and IVB).

No strong unifying etiologic theory exists for bile duct cysts. The pathogenesis is probably multifactorial. In many patients with bile duct cysts, an anomalous junction between the common bile duct and the pancreatic duct can be demonstrated. This occurs when the pancreatic duct empties into the common bile duct more than 1 cm proximal to the ampulla.

Diagram showing the normal anatomy of the biliary and pancreatic ducts.

Diagram showing the biliary tree.

  

Type I

Also known as a true choledochal cyst. It is the most common type and represent 80-90% of bile duct cysts. They consist of saccular or fusiform dilatations of the common bile duct, which involve either a segment of the duct or the entire duct.

• Type IA is saccular in configuration and involves either the entire extrahepatic bile duct or the majority of it.
• Type IB is saccular and involves a limited segment of the bile duct.
• Type IC is more fusiform in configuration and involves most or all of the extrahepatic bile duct.

Type I Cyst should be resected completely to prevent associated complications (i.e. ascending cholangitis and malignant transformation).

Bile Duct Cyst Type I (True Choledochal Cyst).

Type II

Also known as a bile duct diverticulum.It accounts for 3% of all bile duct cysts,  appearing as an isolated diverticulum protruding from the wall of the common bile duct (Saccular outpouchings arising from the supra-duodenal extrahepatic bile duct or the intra-hepatic bile ducts). The cyst may be joined to the common bile duct by a narrow stalk.

Bile Duct Cyst Type II (Bile Duct Diverticulum).

Type III

Also known as a choledochocele. It accounts for 5% of all bile duct cysts, arising from the intra-duodenal portion (distal end) of the common bile duct.

Bile Duct Cyst Type III (Chledochocele).

Type IV

Multiple communicating intra- and extra-hepatic duct cysts. It is the second most common type of bile duct cysts (10%). It is subdivided into sub-types A and B

• Type IVA : fusiform dilation of the entire extrahepatic bile duct with extension of dilation of the intrahepatic bile ducts.
• Type IVB : Multiple cystic dilations involving only the extrahepatic bile duct.
  
  



Bile Duct Cyst Type IV.

Type V

Also known as Caroli disease. Caroli disease is a rare form of congenital biliary cystic disease manifested by cystic dilations limited to intrahepatic bile ducts. It is associated with benign renal tubular ectasia and other forms of renal cystic disease.

Bile Duct Cyst Type V (Caroli Disease).

Oblique View of Lumbar Spine

This view is particularly useful to show the pars interarticularis region and the apophyseal joints. Note that the pars interarticularis is a purely radiological term, its equivalent anatomically being the anterior part of the lamina. The oblique view causes a certain well- known appearance of a Scottie dog: the dog's collar is the pars interarticularis, the eye is the pedicle, the nose is the transverse process and the ear is the superior articular facet. Defects of ossification of the pars may lead to spondylolisthesis. Again, as in the cervical spine, facet articulation disorders can be seen.

Scottie dog.

Cobra Head Sign

Cobra Head.

The cobra head sign is characterized by bulbous dilatation of the distal end of the ureter with a surrounding radiolucent halo, seen within the contrast material–enhanced bladder on intravenous urograms.

The cobra head sign is classically seen with an intravesical ureterocele. This type of ureterocele is also termed orthotopic, since it arises from a ureter with a normal insertion into the trigone. The term ureterocele denotes a cystic ballooning of the distal end of the ureter. What causes ureterocele is not clear. However, the anatomic basis and the mechanism of formation described in the literature is as follows: An intravesical ureterocele results from the prolapse of the mucosa of the terminal segment of the ureter through the ureterovesical orifice into the bladder. This prolapsed ureteral mucosa carries with it a portion of the continuous sheet of the bladder mucosa around the orifice. The prolapsed segment thus has a wall that consists of a thin layer of muscle and collagen interposed between the bladder uroepithelium and the ureter uroepithelium. Since the terminal ureteral orifice is usually narrowed and partially obstructed, and since there is no muscle support for the double mucosal walls of the prolapsed segment, it dilates. This dilated segment fills with urine and protrudes into the bladder.

Frontal urogram after intravenous contrast material administration shows bulbous dilatation of the distal end of the left ureter. Note the surrounding radiolucent halo (arrows).

At intravenous urography, the lumen of the ureterocele is usually filled with contrast material and is surrounded by opacified urine in the bladder. Since the double mucosal wall of the ureterocele is visible as a thin lucent line or halo surrounding its lumen, the ureterocele is outlined, giving the appearance of a cobra head.

In conclusion, the cobra head sign, when present, allows DIAGNOSIS of a URETEROCELE. However, causes of pseudoureterocele, such as a tumor or calculus, need to be ruled out on the basis of the appearance of the surrounding radiolucent halo.

Osgood–Schlatter Disease

Osgood–Schlatter disease (also known as tibial tubercle apophyseal traction injury) is an irritation of the patellar tendon at the tibial tuberosity.  The condition occurs in active boys and girls aged 9–16 years coinciding with periods of growth spurts. It occurs more frequently in boys than in girls. It has been suggested the difference is related to a greater participation by boys in sports and risk activities than by girls.

Lateral radiograph of the knee demonstrating fragmentation of the tibial tubercle with overlying soft tissue swelling.

The condition is usually self-limiting and is caused by stress on the patellar tendon that attaches the quadriceps muscle at the front of the thigh to the tibial tuberosity. Following an adolescent growth spurt, repeated stress from contraction of the quadriceps is transmitted through the patellar tendon to the immature tibial tuberosity. This can cause multiple subacute avulsion fractures along with inflammation of the tendon, leading to excess bone growth in the tuberosity and producing a visible lump which can be very painful when hit.

Diagnosis is made clinically, and treatment is conservative with rest, and if required acetaminophen (paracetamol) or ibuprofen. The condition usually resolves in a few months.

The Yin-Yang Sign

The Ancient Chinese Yin-Yang Symbol.

The yin-yang sign is a finding that may be seen on contrast material–enhanced computed tomographic (CT) scans obtained throughout the body but is primarily seen in the abdomen and the brain. The configuration of a well-defined round or oval mass with increased attenuation in half of its area and decreased attenuation in the other half resembles the ancient Chinese yin-yang symbol.

The yin-yang sign is helpful in FACILITATING DIAGNOSIS of partially thrombosed true arterial aneurysms and false aneurysms. At contrast-enhanced CT, increased attenuation in one portion of the thrombosed aneurysm indicates the presence of a partially contrast material–filled lumen, whereas reduced attenuation in the remaining portion of the thrombosed aneurysm indicates the presence of a mural thrombus. 

An aneurysm is defined as the focal or diffuse DILATION of an artery to more than 50% of its normal diameter. True aneurysms are caused by either acquired or congenital arterial disease for which all layers of the vessel wall are dilated but intact. False aneurysms are acquired lesions that lack an arterial wall and are constrained by the surrounding hematoma and soft tissues. True and false aneurysms may grow rapidly WITHOUT SYMPTOMS and may even reach large dimensions. Their diagnosis is fundamental in avoiding rupture, which can be sudden and life threatening. Because large and giant aneurysms and false aneurysms tend to thrombose (usually partially), the blood flow may fill only part of the lesion.

In almost every part of the human body, the presence of the yin-yang sign may increase suspicion of a partially thrombosed aneurysm; however, this sign is particularly helpful for areas such as the brain and the abdomen, in which several diseases may mimic an aneurismal vessel. Specifically, in the brain, the differential diagnosis between cerebral aneurysms and other lesions (eg, large, partially, and/or cystic suprasellar meningiomas; craniopharyngiomas; or pituitary tumors) may often be difficult, particularly at CT. Also, large basilar aneurysms can, at times, simulate meningiomas or oligodendrogliomas. Finally, hemorrhagic metastases or metastases with areas of high protein content (eg, those in the colon or thyroid) may all be included in the differential diagnosis of mixed lesions that mimic the yin-yang sign.         

      

Transverse contrast-enhanced CT scan of the brain in a patient with giant suprasellar partially thrombosed aneurysm.

  

In the abdomen, the yin-yang sign is often helpful in differentiating aneurysms from other masses that are commonly seen in the left upper quadrant, including cystic pancreatic tumors, islet cell tumors, solid and epithelial neoplasms, pseudocysts, gastric leiomyomas, and leiomyosarcomas. The yin-yang sign is not, however, a specific sign for partially thrombosed or false aneurysms. Although rare, some neoplasms, such as solid and papillary epithelial neoplasms, may demonstrate the yin-yang sign.

Transverse contrast-enhanced abdominal CT scan obtained during arterial phase in patient who underwent orthotopic liver transplantation and had a partially thrombosed splenic artery aneurysm. Posterior hypoattenuating mural thrombus (arrow) and anterior hyperattenuating contrast material–filled lumen (arrowhead) demonstrate yin-yang sign.

            

Because the presence of the yin-yang sign cannot lead to a definitive diagnosis of partially thrombosed aneurysms, the absence of this sign when an aneurysm is suspected is not an otherwise valid criterion for definitely excluding aneurysm. For example, when the thrombus is concentric rather than eccentric, the typical yin-yang pattern is not seen. In conclusion, the yin-yang sign seen at contrast-enhanced CT raises the strong possibility of a diagnosis of aneurysm.

                                                             

Terry Thomas Sign

Terry-Thomas sign is refered to an increase in the scapho-lunate space on an anterio-posterior (AP) radiography or coronal CT of the wrist. The increased distance indicates scapho-lunate dislocations or dissociation (rotary sub-luxation of the scaphoid) due to ligamentous injury. This gap between the scaphoid and lunate bones is more than 3 mm on AP view radiography or coronal wrist CT.

AP radiograph showing a gap between the scaphoid and lunate bones which is known as Terry-Thomas Sign.

This sign is named after well-known British comic Terry-Thomas (1911 - 1990), who had a large gap between his two front teeth.

British Comic Terry-Thomas (1911-1990).

Knutsson's Sign

In 1942 Knutsson correlated vacuum phenomenon (VP) with disc degeneration. In current radiological practice, the general and universally accepted term “vacuum phenomenon” is incorrectly used to characterize gas-like density that can either be due to true VP caused by a rapid increase in the volume of joint space (“acute VP” as seen in the protraction of the shoulder in children) or represent a true gas as commonly seen in degenerative disc of the spine, called “subacute” or “chronic VP”.

These lucent areas are produced by gas, mainly nitrogen, accumulating in the clefts and are accentuated on radiography obtained during extension of the spine. Vacuum phenomena are a reliable indicator of disk degeneration, and their visualization virtually excludes the presence of tumor or infection.

 Vacuum phenomenon. Gas collects in the disk clefts and radiolucent areas appear (red arrows).