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Radiology Quiz
Current Orthopaedics (2008) 22, 295e299
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/cuor
QUIZ
Radiology Quiz R.J. Robinson Department of Radiology, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
Questions Question 1 Figure 1a and 1b are Proton density T2 weighted MRI sequences of the left knee in a patient following an isolated traumatic incident. What radiological signs are visible in each? What is the diagnosis?
Figure 1b
Question 2 What is the diagnosis? What are the complications? Which imaging modality is the most appropriate for further investigation?
Figure 1a 0268-0890/$ - see front matter doi:10.1016/j.cuor.2008.06.001
Figure 2
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Question 3 What is the finding on this plain radiograph of the ankle? Give a differential diagnosis? What investigation should be performed next?
Figure 4b
Question 5 What are the abnormalities on each of the imaging modalities? What is the diagnosis?
Figure 3
Question 4 Fig 4a and 4b are T2 weighted MRI sequences of the knee. What is the diagnosis? Figure 5a
Figure 4a
Figure 5b
Radiology quiz
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Figure 1b
Figure 5c
Question 6 Figure 6 is a coronal CT image on bone windows from a middle aged woman with shoulder pain. What are the differences between the right and left clavicles? What is the diagnosis? What clinical findings might you expect to find?
Figure 6
Answers Answer 1 Figure 1a shows: i) Joint effusion, ii) Double PCL sign with truncated posterior horn of medial meniscus, iii) Intact PCL.
Figure 1b shows: i) Joint effusion, ii) oedema at proximal aspect of LCL, iii) meniscal fragment lying within the intercondylar notch, iv) truncated body of the medial meniscus. Diagnosis: Bucket handle tear of medial meniscus with the displaced fragment lying within the intercondylar notch. Associated lateral collateral ligament (LCL) injury (full extent of the injury is not categorised on a single image). Bucket handle meniscal tears are vertical peripheral tears with displaced medial portion to the intercondylar notch. They occur more commonly in the medial meniscus and clinical presentation usually involves pain and locking following trauma. In normal sagittal imaging the menisci have a ‘‘bow tie’’ appearance. In figure 1a the posterior portion of the ‘‘bowtie’’ is missing and is seen lying anterior to the posterior cruciate ligament (PCL) giving a double PCL sign. In normal coronal imaging the menisci should be roughly symmetrical in size and appearance. In figure 1b the medial meniscal body is small compared to the lateral and there is an extra structure lying within the intercondylar notch along with the ACL and PCL. With all meniscal tears it is important to look for associated injuries. Fluid/oedema gives a bright appearance on T2 weighted imaging. Normal ligaments have a uniform black signal characteristic hence the presence of high signal at the origin of the LCL indicates oedema and injury. The path of the ligament needs to be followed on all images within a sequence to determine whether it is intact or not. Answer 2
Figure 1a
Figure 2 shows posterior dislocation of the medial end of the left clavicle. The displaced clavicular head is seen overlying the manubrium in an infero-medial location. Posterior dislocations are less common than anterior but have more serious implications. Approximately 25% of posterior dislocations are associated with tracheal, esophageal, or great vessel injury. Complications include; tracheal rupture or erosion, pneumothorax, laceration of the superior vena cava, occlusion of the subclavian artery and/or vein, recurrent dislocation, decreased range of motion and residual swelling or deformity. CT is the next appropriate investigation and should include the contralateral clavicle for comparison. CT will
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determine the position of the medial clavicle as well as provide information regarding complications. Figure 2b is an axial image on soft tissue window setting from the CTexamination in the patient in figure 2a. This shows the posteriorly displaced left clavicle (arrow) lying immediately anterior to and indenting the aortic arch (asterix). No vascular injury was demonstrated in this patient.
Figure 3b
Figure 2b
Answer 3 Figure 3 shows an ill-defined lytic lesion with a faint sclerotic margin located in the distal tibial metaphysis of a paediatric patient. There is no periosteal reaction or associated soft tissue mass. The plain film appearances are non-specific. It shows some characteristics of aggressive lesions in being poorly defined but also the characteristics of a less aggressive process in having a sclerotic margin (indicating bone repair). The differential diagnosis therefore includes: osteomyelitis, primary bone tumour, eosinophillic granuloma, lymphoma and metastases (if there is a history of malignancy). The next appropriate imaging step is to perform an MRI with and without gadolinium to look for imaging characteristics on T1 and T2 weighting along with the contrast enhancement pattern. MRI findings of a well defined fluid filled lesion with surrounding enhancing granulation tissue and a sclerotic margin give a diagnosis consistent with a Brodie’s abscess. Figure 3b (coronal T2 fat suppressed image) and figure 3c (coronal T1 weighted image with gadolinium enhancement). T2 weighted images show fluid as bright whilst on T1 fluid is dark. The Lesion in the tibia is revealed to cross into the epiphysis and contain a pocket of fluid surrounded by a large amount of enhancing tissue (gadolinium shows bright signal on T1). The lesion is well defined with a thin sclerotic rim (arrowheads). There is significant oedema and enhancement in the surrounding bone in keeping with an inflammatory response. An ankle joint effusion is demonstrated (arrow). The talus is unaffected and returns normal signal.
Figure 3c
This is a form of subacute osteomyelitis which has an insidious clinical onset. It typically occurs in patients from 2e 15 years of age and involves the metaphysis due to its increased blood supply. Diagnosis is important because surgical drainage is required as antibiotics will not penetrate the abscess cavity. Answer 4 Diagnosis: Pigmented Villonodular Synovitis (PVNS). Figure 4a (axial T2 weighted MRI image through the distal femur at the level of the superior patella) and Figure 4b (sagittal T2 weighted MRI) reveal a large knee joint effusion (high signal T2) containing multiple frond like low signal projections. PVNS is characteristically of low signal on all pulse sequences due to the presence of haemosiderin. PVNS is a locally destructive fibrohistiocytic proliferation of synovial membranes which can affect joints, bursae and tendon sheaths. It can occur in a localised form
Radiology quiz (extraarticular) which is termed Giant Cell Tumour of the Tendon Sheath or diffuse (intraarticular) as in this case.
299 Pre-operative angiography reveals peripheral hypervascularity and embolisation is often performed to reduce the risk of haemorrhage during surgery.
Answer 5 Answer 6 Figure 5a (frontal radiograph of the lumbar spine) reveals absence of the right L5 pedicle and destruction of the right side of the vertebra. Figure 5b (axial unenhanced CT on bone windows through the L5 vertebral body) shows destruction of the posterior elements centered on the right side of the L5 vertebra. The lesion is lytic with bone expansion and a thin circumferential cortical rim. Figure 5c (axial T2 weighted MRI corresponding to fig 5b) reveals the lesion to contain multiple fluid-fluid levels. Diagnosis: Aneurysmal Bone Cyst. This case highlights the characteristic findings of a spinal aneurysmal bone cyst (ABC). These are benign bone lesions containing thin-walled blood filled cystic cavities. The most common location for an aneurysmal bone cyst is in the metaphysis of long tubular bones (70e80%) however approx 15% occur in the spine where they have a predilection for the posterior elements. Plain radiography reveals an expanded lytic lesion with a sclerotic margin and internal trabeculation. CT may better define the extent of the lesion and the involvement of soft tissues whilst MRI shows a well-defined lobulated lesion containing multiple fluid-fluid levels. Fluid-fluid levels have been described in many other bone lesions both benign and malignant but are most commonly seen in an ABC. It highlights the importance of characterising any bone lesion using all the imaging modalities available. In this case a single, expanded lytic lesion in the posterior elements with a thin remnant of cortex and multiple fluid fluid levels on MRI make anything other than an ABC very unlikely.
The right clavicle is expanded and uniformly sclerotic consistent with hyperostosis. There is no periosteal reaction. The sterno-clavicular joint space is normal and there is no bony destruction. Findings are suggestive of a non-aggressive process. Hyperostosis of the clavicle in the absence of a known malignancy, signs of infection or aggressive radiological features such as bone destruction and periosteal reaction is suggestive of SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis and osteitis). This syndrome comprises a spectrum of disorders which share some radiological, clinical and pathological characteristics. These range from chronic recurrent multifocal osteomyelitis to sterno-clavicular osteitis with any combination of the dermatological and musculoskeletal findings from which the syndrome is named. The cause of SAPHO is unknown but has been linked by some to bacterial and viral infections, or autoimmune disease but no causative organism or immune complex has ever been isolated. Careful history taking is important as a 20 year interval between skin and bone lesions has been reported. The anterior chest wall and in particular the sterno-clavicular region is the most frequent site of bony involvement being affected in 70e90% of people. Sclerosis is the most common bone finding but lysis can occur early in the disease. Bone lesions can also be seen in the spine and appendicular skeleton. These provide a greater diagnostic challenge as the lesions often mimick infection and tumour especially in the absence of skin lesions. The lesions generally show increased uptake on bone scintigraphy and biopsy may ultimately be necessary to provide a diagnosis.
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/cuor
QUIZ
Radiology Quiz R.J. Robinson Department of Radiology, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
Questions Question 1 Figure 1a and 1b are Proton density T2 weighted MRI sequences of the left knee in a patient following an isolated traumatic incident. What radiological signs are visible in each? What is the diagnosis?
Figure 1b
Question 2 What is the diagnosis? What are the complications? Which imaging modality is the most appropriate for further investigation?
Figure 1a 0268-0890/$ - see front matter doi:10.1016/j.cuor.2008.06.001
Figure 2
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R.J. Robinson
Question 3 What is the finding on this plain radiograph of the ankle? Give a differential diagnosis? What investigation should be performed next?
Figure 4b
Question 5 What are the abnormalities on each of the imaging modalities? What is the diagnosis?
Figure 3
Question 4 Fig 4a and 4b are T2 weighted MRI sequences of the knee. What is the diagnosis? Figure 5a
Figure 4a
Figure 5b
Radiology quiz
297
Figure 1b
Figure 5c
Question 6 Figure 6 is a coronal CT image on bone windows from a middle aged woman with shoulder pain. What are the differences between the right and left clavicles? What is the diagnosis? What clinical findings might you expect to find?
Figure 6
Answers Answer 1 Figure 1a shows: i) Joint effusion, ii) Double PCL sign with truncated posterior horn of medial meniscus, iii) Intact PCL.
Figure 1b shows: i) Joint effusion, ii) oedema at proximal aspect of LCL, iii) meniscal fragment lying within the intercondylar notch, iv) truncated body of the medial meniscus. Diagnosis: Bucket handle tear of medial meniscus with the displaced fragment lying within the intercondylar notch. Associated lateral collateral ligament (LCL) injury (full extent of the injury is not categorised on a single image). Bucket handle meniscal tears are vertical peripheral tears with displaced medial portion to the intercondylar notch. They occur more commonly in the medial meniscus and clinical presentation usually involves pain and locking following trauma. In normal sagittal imaging the menisci have a ‘‘bow tie’’ appearance. In figure 1a the posterior portion of the ‘‘bowtie’’ is missing and is seen lying anterior to the posterior cruciate ligament (PCL) giving a double PCL sign. In normal coronal imaging the menisci should be roughly symmetrical in size and appearance. In figure 1b the medial meniscal body is small compared to the lateral and there is an extra structure lying within the intercondylar notch along with the ACL and PCL. With all meniscal tears it is important to look for associated injuries. Fluid/oedema gives a bright appearance on T2 weighted imaging. Normal ligaments have a uniform black signal characteristic hence the presence of high signal at the origin of the LCL indicates oedema and injury. The path of the ligament needs to be followed on all images within a sequence to determine whether it is intact or not. Answer 2
Figure 1a
Figure 2 shows posterior dislocation of the medial end of the left clavicle. The displaced clavicular head is seen overlying the manubrium in an infero-medial location. Posterior dislocations are less common than anterior but have more serious implications. Approximately 25% of posterior dislocations are associated with tracheal, esophageal, or great vessel injury. Complications include; tracheal rupture or erosion, pneumothorax, laceration of the superior vena cava, occlusion of the subclavian artery and/or vein, recurrent dislocation, decreased range of motion and residual swelling or deformity. CT is the next appropriate investigation and should include the contralateral clavicle for comparison. CT will
298
R.J. Robinson
determine the position of the medial clavicle as well as provide information regarding complications. Figure 2b is an axial image on soft tissue window setting from the CTexamination in the patient in figure 2a. This shows the posteriorly displaced left clavicle (arrow) lying immediately anterior to and indenting the aortic arch (asterix). No vascular injury was demonstrated in this patient.
Figure 3b
Figure 2b
Answer 3 Figure 3 shows an ill-defined lytic lesion with a faint sclerotic margin located in the distal tibial metaphysis of a paediatric patient. There is no periosteal reaction or associated soft tissue mass. The plain film appearances are non-specific. It shows some characteristics of aggressive lesions in being poorly defined but also the characteristics of a less aggressive process in having a sclerotic margin (indicating bone repair). The differential diagnosis therefore includes: osteomyelitis, primary bone tumour, eosinophillic granuloma, lymphoma and metastases (if there is a history of malignancy). The next appropriate imaging step is to perform an MRI with and without gadolinium to look for imaging characteristics on T1 and T2 weighting along with the contrast enhancement pattern. MRI findings of a well defined fluid filled lesion with surrounding enhancing granulation tissue and a sclerotic margin give a diagnosis consistent with a Brodie’s abscess. Figure 3b (coronal T2 fat suppressed image) and figure 3c (coronal T1 weighted image with gadolinium enhancement). T2 weighted images show fluid as bright whilst on T1 fluid is dark. The Lesion in the tibia is revealed to cross into the epiphysis and contain a pocket of fluid surrounded by a large amount of enhancing tissue (gadolinium shows bright signal on T1). The lesion is well defined with a thin sclerotic rim (arrowheads). There is significant oedema and enhancement in the surrounding bone in keeping with an inflammatory response. An ankle joint effusion is demonstrated (arrow). The talus is unaffected and returns normal signal.
Figure 3c
This is a form of subacute osteomyelitis which has an insidious clinical onset. It typically occurs in patients from 2e 15 years of age and involves the metaphysis due to its increased blood supply. Diagnosis is important because surgical drainage is required as antibiotics will not penetrate the abscess cavity. Answer 4 Diagnosis: Pigmented Villonodular Synovitis (PVNS). Figure 4a (axial T2 weighted MRI image through the distal femur at the level of the superior patella) and Figure 4b (sagittal T2 weighted MRI) reveal a large knee joint effusion (high signal T2) containing multiple frond like low signal projections. PVNS is characteristically of low signal on all pulse sequences due to the presence of haemosiderin. PVNS is a locally destructive fibrohistiocytic proliferation of synovial membranes which can affect joints, bursae and tendon sheaths. It can occur in a localised form
Radiology quiz (extraarticular) which is termed Giant Cell Tumour of the Tendon Sheath or diffuse (intraarticular) as in this case.
299 Pre-operative angiography reveals peripheral hypervascularity and embolisation is often performed to reduce the risk of haemorrhage during surgery.
Answer 5 Answer 6 Figure 5a (frontal radiograph of the lumbar spine) reveals absence of the right L5 pedicle and destruction of the right side of the vertebra. Figure 5b (axial unenhanced CT on bone windows through the L5 vertebral body) shows destruction of the posterior elements centered on the right side of the L5 vertebra. The lesion is lytic with bone expansion and a thin circumferential cortical rim. Figure 5c (axial T2 weighted MRI corresponding to fig 5b) reveals the lesion to contain multiple fluid-fluid levels. Diagnosis: Aneurysmal Bone Cyst. This case highlights the characteristic findings of a spinal aneurysmal bone cyst (ABC). These are benign bone lesions containing thin-walled blood filled cystic cavities. The most common location for an aneurysmal bone cyst is in the metaphysis of long tubular bones (70e80%) however approx 15% occur in the spine where they have a predilection for the posterior elements. Plain radiography reveals an expanded lytic lesion with a sclerotic margin and internal trabeculation. CT may better define the extent of the lesion and the involvement of soft tissues whilst MRI shows a well-defined lobulated lesion containing multiple fluid-fluid levels. Fluid-fluid levels have been described in many other bone lesions both benign and malignant but are most commonly seen in an ABC. It highlights the importance of characterising any bone lesion using all the imaging modalities available. In this case a single, expanded lytic lesion in the posterior elements with a thin remnant of cortex and multiple fluid fluid levels on MRI make anything other than an ABC very unlikely.
The right clavicle is expanded and uniformly sclerotic consistent with hyperostosis. There is no periosteal reaction. The sterno-clavicular joint space is normal and there is no bony destruction. Findings are suggestive of a non-aggressive process. Hyperostosis of the clavicle in the absence of a known malignancy, signs of infection or aggressive radiological features such as bone destruction and periosteal reaction is suggestive of SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis and osteitis). This syndrome comprises a spectrum of disorders which share some radiological, clinical and pathological characteristics. These range from chronic recurrent multifocal osteomyelitis to sterno-clavicular osteitis with any combination of the dermatological and musculoskeletal findings from which the syndrome is named. The cause of SAPHO is unknown but has been linked by some to bacterial and viral infections, or autoimmune disease but no causative organism or immune complex has ever been isolated. Careful history taking is important as a 20 year interval between skin and bone lesions has been reported. The anterior chest wall and in particular the sterno-clavicular region is the most frequent site of bony involvement being affected in 70e90% of people. Sclerosis is the most common bone finding but lysis can occur early in the disease. Bone lesions can also be seen in the spine and appendicular skeleton. These provide a greater diagnostic challenge as the lesions often mimick infection and tumour especially in the absence of skin lesions. The lesions generally show increased uptake on bone scintigraphy and biopsy may ultimately be necessary to provide a diagnosis.