Gout

Regarding Gout,

1. Involvement of axial skeleton is rare.
2. Radiological changes are seen in 1-2 years after first clinical symtpoms.
3. Joint space loss and periarticular osteopenia are commonly encountered.
4. Tophi typically intensely enhance following gadolinium.
5. On ultraound, 'double counter sign' is highly suggestive of gouty arthritis

Answers: T, F, F, T, T

Explanation: 

1. 1st MTPJ is the most common joint affected, followed by 1st IPJ and TMTJ. Lower limbs are more often affted than upper limbs. Feer, wrist and elbows are commonly affected. Axial skeleton is rarely affected. 
2. It takes 5-10 years to develop the radiological changes after first clinical symtpoms.
3. Punched out periarticular erosion with overhanging margins are hallmark of gouty arthritis. The joint spaces are preserved till late stage. Periarticular osteopenia is not a feature of gout. In late stages, diffuse osteopenia may be seen.
4. Tophi show low-to-intermediate signal on T1 and t2, and intensely enhance following contrast.
5. 'Double counter sign' is seen as a hyperechoic irregular rim over the articular cartilage, and is considered a speific feature of gout, and is believed to be secondary to MSU crystals on the cartilage.

Reference:
S. Dhanda, A re-look at an old disease: A multimodality review on gout, Clinical Radiology, Volume 66, Issue 10, October 2011, Pages 984-992

Tuberculosis

Regarding tuberculosis,

1. Radiographic evidence of hilar lymphadenopathy is more common in adults than in children
2. Cavitation is hallmark of post-primary TB
3. In TB meningitis, abnormal meningeal enhancement is more often seen in the basal cisterns
4. In spinal TB, calcification of abscess is characteristic
5. Calcification is seen more than 50% of renal TB

Answers: F, T, T, T, T

Notes: Radiographic evidence of lymphadenopathy is more common in children (96%) than in adults (46%) and more often seen in the right hilar and right paratracheal location. Cavitation is hallmark of post-primary TB, where as lymphadenopathy is rare (5%). Calcification of abscess is highly specific of TB spine. In renal TB, calcification is seen in more than 50% and the other findings include calcyceal deformity and papillary necrosis.

Reference: Burrill J et al. Tuberculosis: A Radiologic Review. RadioGraphics 2007;27:1255-1273

Stress fractures

Regarding stress fractures,

1. Plain radiographs eventually pick up to 90% of stress fractures
2. Bone scintigraphy is sensitive and specific method of diagnosing stress fractures
3. CT is less sensitive than bone scintigraphy is the early diagnosis of stress fracture
4. T1WI are most sensitive sequences in the diagnosis of early stress injury
5. Fracture line in stress fracture is typically oriented perpendicular to the cortex

Answers: F, F, T, F, T

Notes: Plain radiographs detect 15% of early fractures and eventually pick up to 50% of stress fractures. Bone scintigraphy is sensitive but not a specific method of diagnosing stress fractures as infection, necrosis and tumors can mimic stress fractures. Fluid sensitive sequences (STIR or fat-sat T2WI) are most sensitive MR sequences in early detetction of stress injuries and T1WI better demonstrate advanced fractures.

Reference: Datir AP et al. Stress-related bone injuries with emphasis on MRI.Clinical Radiology Volume 62 Pages 828-836

Sickle cell disease

Regarding sickle cell disease,

1. Mandible is usually spared from marrow expansion
2. On MR, irregular peripheral marrow enhancement around a nonenhancing center is more suggestive of osteomyelitis than infarction
3. Extramedullary haemopoitic tissue is shown as low signal on T1WI and high signal on T2WI
4. Hand-foot syndrome commonly affects infants
5. Sickle cell dactylitis is usually secondary to salmonella species

Answers: F, T, F, T, F

Notes:
Facial bones are usually spared from marrow expansion. Gadolinium enhanced MR demonstrates irregular peripheral marrow enhancement around a nonenhancing center in osteomyelitis. Extramedullary haemopoitic tissue is shown as intermediate signal on both T1WI and T2WI. Hand foot syndrome (sickle cell dactylitis) commonly affects between 6months and 2 years and is infarction of small bones of hands and feet.

Reference:
Ejindu VC et al. Musculoskeletal Manifestations of Sickle Cell Disease. RadioGraphics 2007;27:1005-1021

Marfan's syndrome

The following are true regarding Marfan's syndrome (MS):

1. It is autosomal dominant
2. The most common cause of death is secondary to cardiovascular complications
3. Pectus excavatum is commonly seen in Marfan's syndrome
4. Dural ectasia can be seen on the plain radiographs as widening of the interpedicular distance
5. Spontaneous pneumothorax is usually secondary to bullae

Answers: T, T, T, T, T

Notes:
MS is autosomal dominat disease with the gene located on chromosome 15. Aortic dissection, heart failure and vavular disease are the most common causes of death in more than 90%. The cardiovascular manifestations include annuloaortic ectasia, aortic aneurysm, aortic dissection, pulmonary arterial dilatation. Musculoskeletal menifestations include scoliosis, pectus excavatum, pectus carinatum, arachnodactyly, protrusio acetabuli. Dural ectasia may be seen as widened interpedicular distance. Pulmonary manifestations include interstitial lung disease, bullous emphysema, bronchial anomalies, bronchiectasis, spontaneous pneumothorax.

Reference:
Ha H I et al. Imaging of Marfan Syndrome: Multisystemic Manifestations. RadioGraphics 2007;27:989-1004

Sickle cell disease

Regarding sickle cell disease,

1. The most common cause of death is stroke
2. Intracranial anuesysms associated with sickle cell disease are usually single
3. Moya moya is characterictic of sickle cell disease
4. "hair-on-end"appearance on the skull radiograph is characteristic feature of sickle cell disease
5. The most common cause of osteomyelitis is salmonella

Answers: F, F, F, F, T

Notes:
The most common cause of death in sickle cell disease (SCD) is pulmonary complications. Children with SCD are 100 times more risk for pneumonias. Acute chest syndrome is more lethal in adults than children. The most common complication in brain are stroke, ischemia and atrophy. 11% have stroke by the age of 20 years. Infarcts are common in children and haemorrhage in adults. Moyamoya is secondary to large vessel occlusion with telangiectactic colateral circulation and seen in SCD, tuberous sclerosis, neurofibromatosis, vasculitides, infection. Intracranial anuerysms associated with SCD are usually multiple (57%) and 30% are seen in posterior circulation.

"Hair-on-end" appearance is seen in any anaemia. SCD patients are prone for bone infarcts and osteomyelitis, especially from salmonella. Osteomyelitis most commonly affects diaphysis of long bones.

Reference:
Madani G et al. The radiological manifestations of sickle cell disease. Clinical Radiology. Volume 62, Pages 528-538

Renal trauma

Regarding blunt injury of the kidney,

1. Nearly 50% of renal injuries are treated surgically
2. Presence of hematuria is an idication of serioud renal injury
3. Absence of hematuria excludes renal injury
4. Cortical rim sign on CT scan suggests devascularization
5. Hypertension is a known late complication of renal trauma

Answers: F, F, F, T, T
Notes: About 95% of isolated renal injuries are minor and are managed conservatively. Hematuria is seen in 95% of renal injuries, but absence of hematuria does not exclude renal trauma. Hematuria may be absent in severe renal trauma (25% of renal artery thrombosis may not have hematuria). Hematuria with hypotension is associated with increased risk of significant renal injury; but there is poor correlation between severity of hematuria and severity of renal injury. Complete devascularization shows absent nephrogram or cortical rim nephrogram. Early complications include urinary extravasation and urinoma formation, delayed bleeding, infection of the urinoma, perinephric abscess, sepsis, arteriovenous fistula, pseudoaneurysm and hypertension. Late complications include hydronephrosis, hypertension, calculus formation and chronic pyelonephritis.
References:
1. Fanney DR et al.CT in the diagnosis of renal trauma. RadioGraphics 1990; 10: 29.S201-214
2. Kawashima A et al.Imaging of Renal Trauma: A Comprehensive Review. RadioGraphics 2001; 21: 57

Splenic trauma

Regarding splenic injury,

1. Spleen is the most commonly injured abdominal organ in blunt trauma
2. 40% of rib fractures are associated with splenic injuries
3. 40% of splenic injuries are associated with rib fractures
4. Splenic lacerations are seen as an area of low attenuation on contrast enhanced CT scan
5. Most of the splenic injuries are managed surgically

Answers: T, F, T, T, F
Notes:
Spleen is the most commonly injured solid abdominal organ. Most often due to blunt trauma and often (30-60%) associated with other organ injuries. 25% of left renal injury and 20% of left rib fractures are associated with splenic injury. 40% of splenic lacerations are associated with rib fractures. 20% of splenic injuries occur during surgical procedures. Spontaneous rupture can occur in an abnormal spleen, like in infectious mononucleosus or malaria. Subcapsular hematoma is seen as cresentic/lentiform low attenuation. Parenchymal lacerations are seen as irregularly low attenuation areas. Fracture is seen as complete seperation. Disruption of the capsule causes intraperitoneal hemorrhage. Late complications include splenic pseudocyst.
Grading: Grade 1 – Minor subcapsular tear or haematoma, Grade 2 – Parenchymal injury not extending to the hilum, Grade 3 – Major parenchymal injury involving vessels and hilum, Grade 4 – Shattered spleen.
Management:Isolated grade 1 and 2 are suitable for conservative management. The patients with cardiovascular instability need surgery, which include repair, spleen conservation surgery (at least 20% of spleen is preserved) and splenectomy. Approximately 30% fail conservative management.
References:
Roberts JL et al. CT in abdominal and pelvic trauma. RadioGraphics 1993; 13: 735

Menisci of the knee

Regarding meniscal injuries of the knee,

1. Posterior horn of the medial meniscus is the most commonly injured meniscus
2. On MRI, the high signal within the menisci has to extend into both parts of articular surfaces to call it a tear
3. Bucket-handle tear is a type of radial tear
4. Bucket-handle tear is more common in the lateral meniscus
5. Meniscal cysts are most commonly associated with horizontal tears

Answers: T, F, F, F, T
Notes: Posterior horn of the medial meniscus is the most commonly injured part of the menisci. The intrasubstance signal change indicated meniscal degeneration. If the high signal reaches at least one articular surface, then it is called a tear (grade 3). Orthoscopically, the meniscal tears are classified as longitudinal, radial and oblique. The bucket-handle tear is a type of longitudinal tear and is 3 times more common in medial meniscus. The meniscal cysts are commonly associated with horizontal tears.
Reference: Click here

Traumatic diaphragmatic rupture

Regarding traumtic diaphragmatic rupture (TDI),

1. TDIs most commonly occur after penetrating trauma
2. Left diaphragm is more commonly ruptured than the right
3. About 50% of TDI are diagnosed acutely
4. The most commonly herniated organ is spleen
5. 'Dependent viscera sign' is a very sensitive CT sign in the diagnosis of TDI

Answers: F, T, F, F, T
Notes: TDIs commonly occur after blunt trauma as in RTA or fall. Because of the liver, the right hemidiaphragm is ruptured less common than the left. Only about 10% of TDIs are diagnosed in acute setting. Stomach is most commonly herniated organ (32%), followed by colon (27%). CT is investigation of choice even in the acute setting. 'Dependent viscera sign' on CT is very sensitive in the diagnosis of TDI. The bowel or abdominal viscera usually do not contact the ribs due to seperation by diaphragm; contact indicates diaphragmatic injury and is known as 'dependent viscera sign'. Sagittal reconstruction is most sensitive and specific in the diagnosis of TDI.
Reference:

1. Eren S et al. Imaging of diaphragmatic rupture after trauma. Clin Rad (2006)61, 467-477
2. ABCs of blunt trauma

posterolateral corner injury of knee

Regarding posterolateral corner injuries of the knee,

1. Posterolateral corner injuries are more common than medial knee injuries
2. Arcuate fracture is a strong indicator of posterior cruciate ligament tear
3. Segond fracture is a strong indicator of posterior cruciate ligament tear
4. Popliteus myotendinous injury is usually associated with other posterolateral corner injuries
5. Lateral collateral ligament injury is a part of posterolateral corner injuries

Answers: F, T, F, T, T
Notes: Posterolateral corner injuries are less common than medial knee injuries, but more debilitating. The bone injuries include Segond fracture (indicator of ACL injury), Arcuate fracture (avulsion fracture of fibular head - indicator of PCL injury), anterior rim tibial plateau fracture (indicator of PCL injury) and Gerdy's tubercle avulsion fracture. Soft tissue injuries include lateral collateral ligament, biceps tendon, popliteus, lateral head of gastrocnemius, fabellofibular ligament, arcuate ligament and mid-third lateral capsular ligament.
Reference: Harish S et al. Imaging of the posterolateral corner of the knee. Clin Rad (2006) 61, 457-466

Bone tumours of Ribs

Regarding the benign bone tumours of the ribs,

1. Enchondroma (EC) are the most common benging tumours of the ribs.
2. Fibdrous dysplasias (FD) are usually seen in the posterior or lateral aspects of the ribs.
3. MRI is very sensitive in diagnosing the non-calcified cartilage of enchondroma.
4. In osteochondromas (OC), cartilage cap of less than 10mm is highly suspicious for malignant transformation.
5. Aneurysmal bone cysts (ABC) are commonly seen in the anterior aspect of the ribs.

Answers: F, T, T, F, F
Notes: Fibrous dysplasia is the most common benign rib tumour, followed by enchondroma and osteochondroma. FD usually occurs in the posterior or lateral ribs, where as EC and OC occur anteriorly at the costochondral junctions. Hyaline cartilage is not calcified and is best seen on T2WI as a bright signal. Cartilage cap of more than 2 cm in adult and 3 cm in children is highly suspicious for malignant transformation in OC. ABCs are usually seen in the posterolateral aspect of the ribs.
Reference:

1. Hughes et al. Benign primary tumours of the ribs. Clin rad (2006): 61:314-322

Types of knee injuries

Regarding the injuries of the knee joint,

1. In pivot shift injury, the ACL is commonly injured.
2. Dashboard injury commonly results in the disruption of the ACL.
3. In lateral patellar dislocation, the oedema is seen in the inferolateral patella and the anterior aspect of the lateral femoral condyle.
4. In lateral patellar dislocation, the lateral patello-femoral ligament may be injured.
5. 'Kissing contusions' on the anterior aspects of the femur and tibia are seen in hyperextension injury.

Answers: T, F, F, F, T
Notes: Pivot shift injury is a non-contact, vulgus injury with femoral internal rotation commonly seen in skiers and Rugby players and the ACL is commonly disrupted. In dashboard injury, the knee is in 90° flexion with anterior force, leading to disruption of the taut PCL. In lateral patellar dislocation, the injury is on the inferomedial ascpect with injury to the inferomedial aspect of the patella, medial retinaculum, MPFL and medial patellotibial ligament. Hyperextension injuries are commonly seen in footballers, leading to kissing conutions, injury to ACL, PCL or menisci.
Reference: Timothy G. Sanders, Monica A. Medynski, John F. Feller, and Keith W. Lawhorn. Bone Contusion Patterns of the Knee at MR Imaging: Footprint of the Mechanism of Injury. RadioGraphics 2000; 20: 135.

Thalassaemia

Regarding thalassaemia,

1. Skeletal changes are unusual before 6 months of age.
2. 'Hair-on-end' skull appearance is characteristic for thalassaemia.
3. Ethoid air cells are usually absent.
4. Earliest changes are seen in the hand/feet bones.
5. MRI is sensitive in the early diagnosis of chelator toxicity in the skeleton

Answers: T, F, F, T, T
Notes: The skeletal changes in thalassaemia are unusual before 6 months of age and the first changes are usually seen in the hands and feet. 'Hair-on-end' appearance can be seen in any form of severe anaemia. Due to extra-medullary haemopoisis, the paranasal sinuses are not developed, except ethmoid air cells due to the absence of the red marrow around them. Iron chelation also causes changes in the skeleton, in the form of meta-epiphyseal dysplasia (one third of patients) and osteoporosis. Distal ulna is one of the earliest site to show dysplastic changes.
References:

1. Tyler PA et al. The radiological appearances in thalassaemia. Clin Rad 2006:61:40-52.
2. Dahnert W. Radiology review manual 5th edition. Lippincott williams and Wilkins 2003: 165-166