Imaging of Bone Neoplasms

Objectives 

• To describe the role of imaging in the evaluation of bone tumour

• To state the modes of imaging and their application and limitations

• To identify and differentiate between a aggressive (malignant) and non aggressive (benign)   bone tumour on imaging

• To correlate pathology of bone tumours with imaging

Role of imaging are three fold in the evaluation of bone tumours

• Diagnosis

• Exact estimation of the extent prior to surgical interventions

• Staging of tumours

Clues on imaging, which helps in diagnosis

• location

• appearance of lesion 

• type of periosteal reaction

• matrix of lesion

• density of lesion

• number of lesions

Clinical presentations of bone tumours
The clinical presentation is very nonspecific such as pain or swelling of a limb or any other region of the body, usually related to trauma. They may present with a pthological fracture or it may even be an incidental finding on imaging for other clinical problem.

Pathological fracture
Could occur at the site of a benign / malignant tumour.

                                  Fig 1 a- Pathological fracture in a Ewings Tumour

                                   Fig 1 b – pathological fracture in a bone cyst

Modes of imaging & applications

• Plain radiography

• MRI

• CT

• Nuclear imaging

Plain Radiography
Plain radiography remains the primary imaging modality. It detects the tumour, characterizes tumours but may not exactly estimate the extent of malignant lesions. It could differentiate a non aggressive ( fig 2) from aggressive tumour in most of the instances. Common non aggressive tumours are giant cell tumour, aneurismal bone cyst, enchondroma and osteochondroma (fig 3a,b,c).

Characteristics of  a non aggressive tumour on plain radiography
1.    Well defined, sclerotic margin
2.    Narrow zone of transition
3.    No breach of cortex
4.    No periosteal reaction
5.    Absence of an associated soft tissue mass

                               fig 2- Non aggressive (Benign) tumour on plain radiography

Common Benign bone tumours

                                                 Fig 2a - Giant cell tumour

                                                 2b- Aneurysmal bone cyst

                                                    2 c – Osteochondroma

Osteochondromas
Osteochondroma ( exostosis) are common benign tumours, which are seen in young adults, less than 20 year old. It has a M : F ratio of 1:3. They are composed of both osteoid tissues and a cartilage cap. The cartilage cap is only visualized on plain radiographs only when it is calcified.Their presentation can be just an incidental finding on imaging or a bony out growth or pain due to pressure effects on adjacent nerves or bursae causing bursitis. It occurs around knee in 40% of the cases. It may undergo malignant transformation, thus needs to follow up arises once it is diagnosed. Treatment is surgical resection and it is offered when they are symptomatic.

     Fig 3 – Osteochondroma at the fibula head causing pressure erosion on tibia


Aggressive (Malignant) bone tumour ( fig 4a,b)

They are characterized on plain radiography by,

• Wide zone of transition

• Periosteal reaction (Codmans trialgle , onion peel, sunray spicules)

• Soft tissue mass

• New bone formation

Types of periosteal reactions seen in malignant bone tumours ( fig 4a, b, c) showing an aggressive (Malignant ) tumour, osteogenic sarcoma on plain radiography with classic Codman triangle of periosteal  reaction sun ray apperance Onion peel periosteal reaction in an Ewing’s tumour.

                                                            Fig 4a AP view of femur

                                                                4 b -  lateral  view of femur

                                            Fig 4c – AP & lateral femur

Role of MRI in  Bone tumours
MRI detects the lesion and helps in characterizing the tumour. It gives an accurate estimate of  the extent of malignant tumours due to it’s inherent imaging characteristics and it’s ability to do multiplanar imaging. It is poor in detecting calcification or new bone formation. Role of  MRI in detecting the extent of the aggressive bone tumour is shown in the figure below.

                                                    Fig 5 – Coronal MRI -  Ewings




Role of CT in Bone tumours
CT is also used to detect extent of bone tumour as multiplanar imaging is feasible like in MRI( fig 6). It has an additional advantage of being able to characterize a bony lesion by identifying calcification and new bone formation. It is also used at the same time to detect  pulmonary metastases in a given case of suspected malignant bone tumour. Osteo chondroma, osteoid osteomas are easily characterized by CT, both being benign bone tumours of young.

          fig 6 - Osteochondroma on CT as an bony outgrowth on this  axial image of upper tibia


Role of Nuclear imaging in Bone tumours
Nuclear imaging studies detect lesions which are bone forming indicating the osteoblastic activity. They detect metastatic disease earlier than x –rays even not symptomatic. It is useful in the management of cancer, on staging and planning the management protocols. They identify metastatic bone disease in common malignancies such as carcinoma of breast, bronchus, prostate.

                    fig 8-  multiple bone metastases in  an isotope bone scan

Metastatic Disease of Bone
Bone metastases are imaged on plain radiography as a preliminary mode of imaging. They can be lytic or sclerotic. Former are more commoner. Sclerotic metastases are predominantly from carcinoma of prostate. In females carcinoma of breast after treatment may give rise to sclerotic or mixed metastases. Skeletal survey was done to detect metastases which is now mostly replaced by more sensitive isotope scanning with less radiation.

Imaging of multiple Myeloma
Is a malignant bone tumour of bone marrow of plasma cell origin. It may start off with plasmacytoma or as multiple myeloma from the beginning. Skeletal surveys were carried out for the diagnosis of multiple myeloma which is characterized by punched out lytic lesions.

Mimics of bone tumours
There are some mimics of bone tumours or rather pit falls in imaging suspected bone tumours. Acute osteomyelitis mimicking Ewing’s sarcoma and benign  Brown tumour or cystic tuberculosis mimicking metastases. 

Arterial system of the lower limb

Femoral artery

It’s the distal continuation of the External Iliac artery beyond the inguinal ligament. Along its course it traverses the femoral triangle and terminates a hand’s breadth above the Adductor tubercle, passing through the hiatus in the Adductor Magnus to become the popliteal artery.


Branches
1) Branches In the Groin
A) Superficial circumflex iliac artery
B) Superficial epigastric artery
C) Superficial external pudendal artery                        

2) Profunda Femoris
            This arises from the femoral artery posterolaterally 5cm distally from the inguinal ligament.    

Conventionally above this branch it’s called the Common iliac artery. Below it the Superficial femoral artery. Profunda femoris has 4 perforating branches, a medial circumflex and a lateral circumflex branch.


Clinical            
Arterial access is obtained into the femoral artery at the groin for Arteriography.

Popliteal Artery

Continues down from the Femoral artery at the Adductor hiatus & terminates at the lower border of the popliteal muscle. It lies deep within the popliteal fossa( It is covered superficially by the popliteal vein and crossed by the tibial nerve).

                                           Popliteal vein above the popliteal artery not compreesd

                                            Popliteal vein above the popliteal artery compressed

                                                              DVT

Branches of the popliteal artery

• Muscular branches

• Geniculate branches (to knee joint)

• Terminal branches- Anterior tibial artery

                                          Posterior tibial artery



Posterior tibial artery

Proximally it descends deep to soleus muscle, and becomes superficial in the lower 3rd of the leg and passes behind the medial malleolus, between the tendons of Flexor digitorum longus and flexor hallucis longus. It’s accompanied by corresponding vein and nerve.

Below the ankle the Posterior tibial artery divides into medial and lateral Plantar arteries which constitutes the main blood supply to the foot. In addition to the branches to muscles and skin it gives off the peroneal artery about 4cm distally from its origin.

Peroneal artery runs down the postrior aspect of the fibula. Above the ankle it gives off its perforating branch which pierces the interosseous membrane, descends over the lateral malleolus to & anastamoses with the arteries of the dorsum of the foot.

Anterior tibial artery  
                                         
After its origin from the bifurcation of the popliteal artery it passes forward between the tibia and the fibula under the lower margin of the popliteus, and descends in the anterior compartment of the leg. At first it’s deeply buried but becomes superficial just above the ankle between the tendons of extensor hallucis longus and tibials anterior.


The artery continues over the dorsum of the foot as the Dorsalis pedis. This gives off the arcuate artery which supplies the cutaneous branches to the back of the toes. Dorsalis pedis runs between the 1st & the 2nd metatarsals to join the lateral plantar artery in the formation of the plantar arch, from which branches run forward to supply the plantar aspect of the toes.

Choledochal cysts - 2

Prevalence
Race

• Persons of Asian ancestry, especially those of Japanese descent, may have a somewhat increased risk.

Sex

• Choledochal cysts are more prevalent in females. The female-to-male ratio is approximately between 3:1 and 4:1.

Presentation

• The clinical history and presentation of a patient with a choledochal cyst varies with the patient's age.

• Overt, dramatic signs and symptoms are more common in infancy, whereas manifestations are more subtle in adulthood.

• Most patients with choledochal cysts have some clinical manifestation of the disease in childhood.

•  Approximately 67% of patients with choledochal cysts have signs or symptoms related to the cyst before they are 10 years of age. 80% before adulthood.

Infants

• Infants frequently come to clinical attention with jaundice and the passage of acholic stools.

• Infants with choledochal cysts can have a palpable mass in the right upper abdominal quadrant; this may be accompanied by hepatomegaly.

Children

• Intermittent bouts of biliary obstructive symptoms or recurrent episodes of acute pancreatitis.

• May also have jaundice and a palpable mass in the right upper quadrant.

• The correct diagnosis is occasionally more difficult in children with pancreatitis.

• An analysis of biochemical laboratory values reveals elevations in amylase and lipase levels. 

Adults

• In adult patients, subclinical bile duct inflammation and biliary stasis have been ongoing for years.

•  Adults with choledochal cysts can present with hepatic abscesses, cirrhosis, recurrent pancreatitis, cholelithiasis, and portal hypertension.

• Uncommon cause of obstructive jaundice!

The most common symptom in adults is abdominal pain. Classic clinical triad of abdominal pain(70-90%), jaundice(30-50%), and a palpable right upper quadrant abdominal mass(25%) has been described in adults with choledochal cysts, although this is found in only 20-30% of patients. Cholangitis can be part of the clinical presentation in adult patients with biliary obstruction.Choledochal cysts not appearing until adulthood can be associated with a number of serious complications resulting from long-standing biliary obstruction and recurrent bouts of cholangitis.


Complications

• Cholelithiasis/choledocholithiasis

• Severe pancreatitis

• Hepatic abscesses

• Hepatic cirrhosis

• Portal hypertension/portal vein thrombosis

• Cholangitis

• 2% risk of malignancy, which may develop in any part of the biliary tree.

• Cyst rupture – biliary peritonitis

• Bleeding

 Preferred Examination

• According to Miyano and Yamataka, the preferred initial radiologic examination in the diagnostic workup of a choledochal cyst is an abdominal ultrasonography (US) scan.

•  US scanning is noninvasive and involves no radiation exposure, and its findings are sensitive and specific for the diagnosis. 

•  Uss-fusiform cyst beneath porta hepatis.

• Separate from gall bladder(c/o double GB,agenesis).

• Communication with CHD/intrahepatic ducts need to be demonstrated.

• Abrupt change of calibre at junction of dilated segment to normal ducts.

• Intra hepatic ducts may be dilated(16%) due to obstruction, but most peripheral ones do not.

Once a preliminary diagnosis is made using US scanning, other supportive studies , including abdominal computed tomography (CT) scans, magnetic resonance imaging (MRI) studies, or magnetic resonance cholangiopancreatographic (MRCP) examination is confirmatory. These studies demonstrate the cyst with more precise anatomic detail, important anatomic relationships.

• UGI studies- RUQ mass,anterior displacement of 2 nd part of duodenum,widening of c loop.

•  HIDA – may not fill with radionuclide, or late filling up to 1 hour.

Limitations of Techniques

• Its effectiveness is dependent on operator experience.

• Cysts on US images may be misinterpreted as the gallbladder or other structures.

• Decreased sensitivity in the presence of overlying bowel gas, pancreatitis, cholangitis, or other inflammatory processes.

• Differentiating a choledochal cyst from a hepatic cyst, hepatic abscess, acute fluid collection, or pancreatic pseudocyst may be difficult.

• If the diagnosis is unequivocal with US scanning, other supportive studies are usually required to adequately plan the surgical approach.

• If doubt remains despite sonographic evidence suggestive of the diagnosis, CT scanning or MRI/MRCP provides the details needed to confirm the diagnosis.

Differential Diagnoses

• Pseudocyst( Pancreatic)

•  Gallbladder duplication

• Enteric duplication cyst

• Other Problems to Be Considered

• Hepatic cystCholangiocarcinomaCholedocholithiasisCholangitis

• Biloma

• Hydronephrotic kidney

• Hepatic artery aneurysm 

 Treatments
Choledochal cysts are treated by surgical excision of the cyst with the formation of a roux-en-Y anastamosis to the biliary duct.

Choledochal cysts

Choledochal cysts are rare (<1%)congenital conditions associated with benign cystic dilatation of bile ducts (>20mm). They consist of cystic dilatations of the extrahepatic biliary tree, intrahepatic biliary radicles, or both. (no /mild peripheral intrahepatic bile duct dilatation).


Presentation 
Most of them present in 1st year of life; adult presentation is rare and usually at this stage is associated with complication . Classic triad of intermittent abdominal pain, jaundice, and a right upper quadrant abdominal mass is found only in minority of patients.

• They were classified into 5 types by Todani in 1977.

• Classification was based on site of the cyst or dilatation. 

Type I choledochal cyst

• These are the most common, representing 80-90% of the lesions.

•  Type I cysts are dilatations of the entire common hepatic and common bile ducts or of segments of each.

• They can be saccular or fusiform.

•  Type I cysts can be divided into 3 subclassifications, including type IA cysts, which are typically saccular and involve all or a major portion of the extrahepatic bile duct (common hepatic duct plus common bile duct). 

Type II choledochal cyst

• These are relatively isolated protrusions or diverticula that project from the common bile duct wall.

• They may be either sessile or connected to the common bile duct by a narrow stalk. 

Type III choledochal cyst

• Also called choledochoceles.

• These are found in the intraduodenal portion of the common bile duct. 

Type IV (A) choledochal cyst

Type IVA cysts –These are characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree. Most frequently, a large, solitary cyst of the extrahepatic duct is accompanied by multiple cysts of the intrahepatic ducts.



Type IVB choledochal cysts – These consist of multiple dilatations that involve only the extrahepatic bile duct.

CT scan demonstrating intrahepatic biliary duct dilatation in a type IV choledochal cyst.

ERCP demonstrating extrahepatic and intrahepatic biliary duct dilatation in a type IV choledochal cyst.

Type V choledochal cyst (Caroli disease)

• These are defined by dilatation of the intrahepatic biliary radicles.

• Often, numerous cysts are present with interposed strictures that predispose the patient to intrahepatic stone formation, obstruction, and cholangitis.

• The cysts are typically found in both hepatic lobes. Occasionally, unilobar disease and most frequently involves the left lobe.

Pathophysiology

• Most likely multifactorial.

• Some aspects of the disease are consistent with a congenital etiology, others with a congenital predisposition to acquiring the disease.

• The vast majority,more than 90% have an anomalous junction of the common bile duct with the pancreatic duct (anomalous pancreatobiliary junction [APBJ]).

•  An APBJ is characterized by the entry of the pancreatic duct into the common bile duct 1 cm or more proximal to where the common bile duct reaches the ampulla of Vater (10-58%).

• In some CBD drains into pancreatic duct.

This shows the normal relationship between the common bile and pancreatic ducts as they join and pass through the wall of the duodenum (left) and the abnormal relationship (right) in which there is a common channel that permits destructive digestive pancreatic enzymes to enter and damage the common bile duct.
A.). B.) This dye injection of the bile and pancreas ducts shows the typical picture of an abnormal pancreaticobiliary duct junction in association with a choledochal cyst (arrow).

• The APBJ allows pancreatic secretions and enzymes to reflux into the common bile duct.

• In the relatively alkaline conditions found in the common bile duct, pancreatic proenzymes can become activated. 

• This results in inflammation and weakening of the bile duct wall.

From a congenital standpoint,

• defects in epithelialization and recanalization of the developing bile ducts during organogenesis and congenital weakness of the duct wall. 

Sternum, Clavicle & Ribs - 2

Ribs
PA / AP

• Upper ribs

• Lower ribs

Obliques

• (Usually) posterior obliques (RPO, LPO)

• Anterior obliques (RAO, LAO)

Ribs PA
Patient Position

• Position patient erect or prone.

Part Position

• Center midsagittal plane to grid with chin extended and eyes straight ahead.

• Place top of IR approximately 11/2 inches (3.8 cm) above shoulders.

• Have patient roll shoulders forward and rest back of hands on hips.

Respiration:

• Obtain radiograph during suspended full inspiration to depress diaphragm.

Central Ray

• Direct perpendicular to center of Cassette. This places the CR at level of T7.

Ribs AP (above diaphragm)
Patient Position

• Position patient erect or supine.

Part Position

• Center midsagittal plane to midline of grid.

• Place top of cassette 11/2 inches (3.8 cm) above relaxed shoulders.

• Rotate shoulders anteriorly.

Respiration:

• Obtain radiograph during suspended full inspiration.

Central Ray

• Direct perpendicular to center of cassette.

Ribs AP (below diaphragm)
Patient Position

• Position patient erect or supine.

Part Position

• Center midsagittal plane to midline of grid.

• Center thorax with bottom of cassette at level of iliac crests.

Respiration:

• Obtain radiograph during suspended full expiration.

Central Ray

• Direct perpendicular to center of cassette.

Ribs AP obliques (RPO, LPO)
Patient Position

• Position patient erect or supine.

Part Position

• Rotate patient's body 45 degrees with affected side toward IR.

• Center a plane midway between midsagittal plane and lateral surface of body to the bucky.

• Abduct arm nearest bucky, and place hand on head.

• Abduct opposite limb, and place hand on hip.

Center top of IR 1 & 1/2 inches (3.8 cm) above relaxed shoulder (for above diaphragm) and with lower edge of IR at level of iliac crest (for below diaphragm).


Respiration:

• Above diaphragm: Obtain radiograph during suspended full inspiration. Below diaphragm: Obtain radiograph during suspended full expiration.

Central Ray

• Direct perpendicular to center of cassette.

Exposure:- 75 kV, 30-40 mAs

Ribs PA obliques (LAO, RAO)

• Position patient erect or prone.

• Rotate patient's body 45 degrees with affected side away from IR.

• Center a plane midway between midsagittal plane and lateral body surface.

• Abduct and extend arm nearest IR and rest on hip.

• Abduct opposite arm and rest on film holder or head.

• Center top of IR 11/2 inches (3.8 cm) above relaxed shoulder (for above diaphragm) and with lower edge of IR at level of iliac crest (for below diaphragm).

• Above diaphragm: Obtain radiograph during suspended full inspiration. Below diaphragm: Obtain radiograph during suspended full expiration.

• Direct perpendicular to center of IR.

Exposure factors

•  Low kV (70 -80) is recommended to obtain high contrast between bone and soft tissue.

Sternum, Clavicle & Ribs

Sternum
    Projections

•  Oblique (RAO or LAO)

•  Lateral

Sternum Oblique

Oblique (RAO or LAO)
Patient position

• Stands or sits (or lying down) facing the bucky. Midsagittal plane perpendicular.

Part position

• Rotate right or left side 20-30 degrees away from the bucky.

Position of cassette

• Upper edge at 7th cervical vertebra.

• Centre of the cassette at the level of the Midsternum.

Central ray

• To enter perpendicularly at the level of the medial border of the scapula of the raised side & lateral to the spine, exiting midsternum.

Respiration

• Gentle breathing during a long exposure time to blur out the lung markings.

• Exposure :- 75kV, 50 mAs(25mA x 2 sec).

Sternum Lateral
Patient position

• Standing, seated in lateral position (or recumbent).

Part position

• Rotate shoulders  and arms posteriorly for erect position, or, place arms above head for recumbent position.

• Center sternum to bucky in true lateral position.

Position of cassette

• Upper edge 4-5 cm above sternal notch.

• Vertical Centre of the cassette at the level of the sternum.

Central ray 

• To Enter and exit perpendicularly at the lateral border   of midsternum.
• Respiration  :- Suspended deep inspiration.

 Sterno-clavicular joints  Obliques
Patient position

• Prone or seated erect facing the bucky.

 Part position

• Keeping affected side closer to bucky rotate patient’s body enough to project the vertebrae  away from the joint (45 degrees).

• Center sternoclavicular joint centred to the bucky & cassette

 Central ray

• perpendicularly to a point 5 -10cm away from the midline at the level of T2-T3  to exit at the joint.

 Respiration  :- Suspended deep inspiration.

Clavicle AP
 Patient Position

• Position patient erect or supine.

• Turn patient's head away from affected side.

Part Position

• Center clavicle to center of cassette, midway between midline of body and lateral border of shoulder.

Respiration:

• Obtain radiograph during suspended expiration.

Central Ray

• Direct perpendicular to mid-shaft of clavicle.

NOTE: If necessary to decrease part-cassette distance and improve recorded detail, obtain PA clavicle. Place patient facing grid using perpendicular central ray and position using above landmarks.

Clavicle AP axial

• Position patient erect or supine.

• Center clavicle to lower third of cassette, midway between midsagittal plane and lateral border of shoulder.

• Turn patient's head away from affected side if needed.

• Obtain radiograph during suspended inspiration.

• Direct angle 15 to 30 degrees cephalad centered to midshaft of clavicle.

• NOTE: If necessary to decrease part-cassette distance and improve recorded detail, obtain PA axial clavicle. Place patient facing grid using 15 to 20 degrees caudal central ray angulation.

SUBINTIMAL ANGIOPLASTY

Subintimal Angioplasty performed by creating a channel between the intima and the media by means of an intentional dissection and then to perform an angioplasty on this channel to enlarge it and maintain patency.

Indications

• Chronic occlusive arterial disease

• Failed percutaneous transluminal angioplasty (PTA)

• Dissection of native vessel in the presence of an occluded bypass graft

• Long diffuse stenotic disease, particularly in calcified vessels where the long-term patency of PTA is poor

• Flush SFA occlusions where PTA is likely to be impossible

• Reconstructing run-off vessels in the presence of popliteal or trifurcation occlusion

 

                                           SFA and Popliteal occlusion with gangrenoeus foot

                                                          Popliteal occlusion with rest pain

Technique

• Puncture  is  usually  antegrade  SFA  puncture

• A catheter is introduced proximally to the occlusion.

• Catheters

         4F  short catheter with an angled tip
            (Bolia mini-catheter, Terumo, Japan) is used.
        A 5F  pre-dilating straight catheter
             (Van Andel catheter, Cook, UK)
        5F  Cobra catheter may also be used

• Hydrophilic angle tipped  guide wire.

• Baloon catheter of appropriate diameter inflated with 10-12 atm pressure.

Drugs

• Prior to dissection 3000-5000iu intra arterial bolus of heparin is administered.

• Vasodilaters like nitrates or tolazoline.

• Premedicated with aspirin.

• Clopidogrel stopped 7 days prior.

Complications

• Haematoma    - Local             Retroperitoneal

• Peripheral embolism.

• Vessel perforation

• Elastic recoil -treated  vasodilators.

Limitations

• Fresh occlusions

• Heavy plaque Ca++

• Fine cylindrical Ca++

• Extensive diffuse disease

• Common femoral occlusions

Conclusion
A valuable technique that offers:
–  Scope of treatment
–  Long term patency
–  Success with less complication rate
–  Major impact on CLI