Everything you need to know about Computed Tomography (CT) & CT Scanning

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Musculoskeletal: Bone Tumors Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Musculoskeletal ❯ Bone Tumors
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  • Sclerotic Metastases to the Spine: Differential Diagnosis
    • Prostate cancer
    • Breast cancer
    • Carcinoid tumor and other neuroendocrine tumors
    • Mucinous adenocarcinoma of the GI tract
    • Lymphoma
    • Neuroblastoma
  • “Fibrous dysplasia is a noninherited bone disease in which abnormal differentiation of osteoblasts leads to replacement of normal marrow and cancellous bone by immature bone and fibrous stroma. It is usually an incidental imaging finding, generally not requiring further investigation. However, fibrous dysplasia may be complicated by pathologic fracture, and rarely by malignant degeneration.”

    
Imaging Findings of Fibrous Dysplasia with Histopathologic and Intraoperative Correlation 
Fitzpatrick KA et al.
AJR 2004;182:1389–139
  • “Fibrous dysplasia is categorized as either monostotic or polyostotic and may occur as a component of McCune-Albright syndrome or the rare Mazabraud syndrome.”


    Imaging Findings of Fibrous Dysplasia with Histopathologic and Intraoperative Correlation 
Fitzpatrick KA et al.
AJR 2004;182:1389–139
  • “The polyostotic form of fibrous dysplasia may involve many or few bones, most commonly the skull and facial bones, pelvis, spine ,and shoulder. Polyostotic fi- brous dysplasia is often unilateral, some- times showing a monomelic pattern. It tends to involve larger segments of bone and is frequently associated with fractures and severe deformities.”


    Imaging Findings of Fibrous Dysplasia with Histopathologic and Intraoperative Correlation 
Fitzpatrick KA et al.
AJR 2004;182:1389–139
  • “McCune-Albright syndrome is an endocrin- opathy occurring mainly in girls, consisting of the triad of precocious puberty, polyostotic fi- brous dysplasia, and characteristic cutaneous pigmentation. The cutaneous lesions are flat pigmented macules, often referred to as “café au lait” spots and likened to the coast of Maine because of their irregular contour. Fibrous dysplasia lesions associated with McCune-Albright syndrome tend to be more disabling than those of pure polyostotic disease.”

    
Imaging Findings of Fibrous Dysplasia with Histopathologic and Intraoperative Correlation 
Fitzpatrick KA et al.
AJR 2004;182:1389–139
  • OBJECTIVE. The purpose of this study was to determine whether CT attenuation thresholds can be used to distinguish untreated osteoblastic metastases from enostoses.


    CONCLUSION. CT attenuation measurements can be used to distinguish untreated osteoblastic metastases from enostoses. A mean attenuation of 885 HU and a maximum attenuation of 1060 HU provide reliable thresholds below which a metastatic lesion is the favored diagnosis.

    Distinguishing Untreated Osteoblastic Metastases From Enostoses Using CT Attenuation Measurements 
Ulano A et al.
AJR 2016; 207:362–368
  • “The most common malignancy of bone is metastatic disease, affecting approximately 400,000 people in the United States each year. Prostate, breast, and lung cancer account for approximately 80% of skeletal metastases.”


    Distinguishing Untreated Osteoblastic Metastases From Enostoses Using CT Attenuation Measurements 
Ulano A et al.
AJR 2016; 207:362–368
  • “Our study shows that a mean CT attenuation threshold of 885 HU and a maximum attenuation threshold of 1060 HU can be helpful in differentiating untreated osteoblastic metastasis from enostosis with 95% sensitivity and 96% specificity.”


    Distinguishing Untreated Osteoblastic Metastases From Enostoses Using CT Attenuation Measurements 
Ulano A et al.
AJR 2016; 207:362–368
  • “An enostosis is a benign osseous lesion that consists of a focal area of mature compact (cortical) bone within the cancellous bone (spongiosa). The finding was initially described by Stieda and Fischer  in the early 20th century as “compact bone nuclei” and “islands,” respectively.”


    Distinguishing Untreated Osteoblastic Metastases From Enostoses Using CT Attenuation Measurements 
Ulano A et al.
AJR 2016; 207:362–368
  • “In our study, the distribution of tumors may have affected the threshold. For example, if more cases of prostate cancer had been included, the threshold may have been higher. Further investigation should also be performed to confirm these thresholds. Because prostate metastases disproportionately measured out- side the thresholds, lesions in patients with a history of prostate cancer should be interpreted with added caution.”


    Distinguishing Untreated Osteoblastic Metastases From Enostoses Using CT Attenuation Measurements 
Ulano A et al.
AJR 2016; 207:362–368
  • “No single imaging modality is consistently best for the assessment of metastatic bone disease across all tumor types and clinical situations. In some cases, no imaging is indicated.”


    ACR appropriateness criteria on metastatic bone disease.
Roberts CC et al.
J Am Coll Radiol. 2010 Jun;7(6):400-9
  • “Skeletal metastases are the most common malignant tumor in bone. Certain types of cancer (e.g., of the prostate or breast) are particularly likely to give rise to skeletal metastases, with prevalences of up to 70%. The diagnosis of skeletal metastases has a major impact on the overall treatment strategy and is an important determinant of the course of illness and the quality of life. The goal of diagnostic imaging is to detect skeletal metastases early, whenever they are suspected on the basis of clinical or laboratory findings or in patients who are at high risk. Other important issues include assessment of the risk of fracture and the response to treatment.” 


    The Diagnostic Imaging of Bone Metastases
Heindel W et al.
Dtsch Arztebl Int. 2014 Oct; 111(44): 741–747.
  • “MM derived from the following malignancies: lung cancer (25.1%), gastrointestinal tumours (21.0%), and urological tumours (13.2%). Other neoplasias with MM were rare. MM were localised most frequently in the thigh muscles, the extraocular musculature, and the gluteal and paravertebral muscles. The localisation of MM was different in several primary malignancies.”

    Muscle metastases: comparison of features in different primary tumours.
    Surov A,
    Cancer Imaging. 2014 May 6;14(1):21
  • “On computed tomography (CT), five different patterns of MM occurred: masses with homogeneous contrast enhancement (type I, 46.5%), abscess-like lesions (type II, 27.7%), diffuse infiltration with muscle swelling (type III, 18.1%), intramuscular calcifications (type IV, 6.5%), or MM presented as intramuscular bleeding (type V, 1.2%). MM from several primary tumours manifested with different CT patterns.”

    Muscle metastases: comparison of features in different primary tumours.
    Surov A,
    Cancer Imaging. 2014 May 6;14(1):21
  • “According to Haygood et al., most common primary malignancies were lung cancer, sarcomas, melanoma, renal cell carcinoma and breast cancer in decreasing order of frequency. In a previously reported mono-center study, MM from urogenital tumours occurred most commonly, followed by gastrointestinal tumours and malignant melanoma. In the present analysis, lung cancer, gastrointestinal tumours, urogenital tumours, and breast cancer were the most frequent primary malignant diseases.”

    Muscle metastases: comparison of features in different primary tumours.
    Surov A,
    Cancer Imaging. 2014 May 6;14(1):21
  • Secondary Bone Involvement by Lymphoma
    - Secondary involvement of the bone with lymphoma (secondary bone lymphoma) much more common than primary bone lymphoma, occurring in ~15% of disseminated lymphomas.
    - Secondary bone lymphoma is defined as lymphoma involving the bone with nodal disease occurring within six months or secondary lymphoma involving the bone at least six months after diagnosis.
  • Secondary bone involvement can result from direct spread from nodal disease or haematogenous metastases. The axial skeleton is more often affected than the appendicular skeleton . Most frequent locations of involvement are :
    - spine
    - bony pelvis
    - skull
    - ribs
    - facial bones
  • “Lymphoma can involve any part of the musculoskeletal system. Primary musculoskeletal lymphoma is rare but can occur in bone (reticulum cell sarcoma) or in the skin and subcutaneous tissues (mycosis fungoides). Secondary involvement in the musculoskeletal system is more common and can have a variety of radiologic findings. The definitive diagnosis of musculoskeletal lymphoma, however, is difficult to make by using imaging criteria alone.” 

    Lymphoma of bone, muscle, and skin: CT findings.
    P C Malloy, E K Fishman and D Magid
    AJR 1992;159: 805-809.
  • “Primary and secondary bone lymphoma can be indistinguishable radiologically and histologically, but modern imaging techniques allow more accurate differentiation of primary from secondary bone involvement. This pictorial essay illustrates the CT findings of primary and secondary lymphoma involving bone, muscle, and skin and subcutaneous tissues.”

    Lymphoma of bone, muscle, and skin: CT findings.
    P C Malloy, E K Fishman and D Magid
    AJR 1992;159: 805-809.
  • “ Lung cancer is the most common neoplasm diagnosed worldwide. Metastatic presentation of the disease is frequent. Apart from the usual sites of metastatic disease (bone, adrenals, liver, brain), a particular site for metastases is represented by skin. The case we report is about a 66 year-old man with cutaneous metastasis from lung cancer.”
    Cutaneous metastasis from lung cancer. Case report.
    Fratus G et al.
    Ann Ital Chir. 2014 Jul 21;85(epub).
  • “ FD represents approximately 7% of all benign tumour-like bone lesions. However, the spine is affected in only 2.5% of cases, and FD of the spine is very rarely observed without there being disease elsewhere in the body . Spinal involvement occurs mostly in the polyostotic form of FD; it is unusual for it to occur in the monostotic form. When present in the elderly with multiple vertebral lesions, a biopsy may be indicated because metastatic disease or multiple myeloma may simulate a benign non-aggressive process.”
    CT and MRI of fibrous dysplasia of the spine
    Park SD et al
    Br J Radiol Jul 2012; 85(1015):996-1001
  • “However, typical radiographic findings of FD were represented on spine CT scans, with GGO the most common CT finding. In addition, an expansile nature, lytic lesions, sclerotic rims and a decrease in body height were common CT features in our study.”
    CT and MRI of fibrous dysplasia of the spine
    Park SD et al
    Br J Radiol Jul 2012; 85(1015):996-1001
  • “In conclusion, FD should be included in the differential diagnoses of patients with expansile osteolytic lesions with GGO, sclerotic margins or lesions in the vertebral bodies and posterior elements, especially when seen on spine CT scans. Moreover, these characteristic CT imaging findings of spinal FD may be helpful for diagnosing FD on spine CTs and preventing unnecessary procedures, especially in adult patients.”
    CT and MRI of fibrous dysplasia of the spine
    Park SD et al
    Br J Radiol Jul 2012; 85(1015):996-1001
  • Fibrous Dysplasia: Facts
    - Monostotic form usually presents in 2nd-3rd decade of life (ribs, proximal fenur, tibia, craniofascial)
    - Polyostotic form usually presents under age 10 (femur,tibia, pelvis, foot, ribs, skull and fascial bones
  • Fibrous Dysplasia: CT Findings
    - Ground glass lucencies in bone
    - Shepherd’s crook deformity
    - Tibial bowing
    - Sclerotic margins and well defined borders in bone especially spine
    - Expansile changes in bone
  • Fibrous Dysplasia: Differential DX
    - Pagets disease
    - Neurofibromatosis
    - Hyperparathyroidism
    - Giant cell tumor
    - Osteoblastoma
    - Hemangioma
  • Osteoid Osteoma: CT Findings
    -Nidus surrounded by variable amount of sclerosis
    -Nidus may enhance on contrast enhanced CT
    -Periosteal reaction common
    -CT can be used as a guide for RF ablation of the lesion
  • Osteoid Osteoma: Facts
    -Age 5-25 yrs is 90% of cases
    -M:F is 2-1
    -Local pain usually worse at night
    -Common locations include proxiaml femur, hands and feet
    -Classic finding is nidus which is 1.5 cm or less
  • Extraosseous Myeloma: Sites of Involvement
    - Spleen
    - Liver
    - Kidneys
    - Small bowel
    - Lymph nodes
    - Pulmonary nodules
    - Pleural implants
  • "Extraosseous myeloma can affect virtually any organ, and the imaging findings of extraosseous myeloma are nonspecific and can mimic other disorders."

    Imaging of Extraosseous Myeloma: CT, PET/CT, and MRI Features
    Hall MN et al.
    AJR 2010; 195:1057-1065

  • "The presence of radiologically detectable extraosseous myeloma is associated with a poor prognosis and thus is an important factor in the initial workup and follow-up evaluation"

    Imaging of Extraosseous Myeloma: CT, PET/CT, and MRI Features
    Hall MN et al.
    AJR 2010; 195:1057-1065

  • "Extraosseous myeloma may affect any organ and can mimic other malignancies. The objective of this article is to describe the clinical relevance of extraosseous myeloma and to present the diverse imaging findings of extraosseous myeloma."

    Imaging of Extraosseous Myeloma: CT, PET/CT, and MRI Features
    Hall MN et al.
    AJR 2010; 195:1057-1065

  • Secondary Osteosarcoma: facts
    - Tumor arises in preexisting condition in bone like;
    - Pagets disease
    - Prior radiated bone
    - Dedifferentiated chondrosarcoma
    - Bone infarct
  • Osteosarcoma: Differential Dx includes
    - Ewing sarcoma
    - Chondrosarcoma (clear cell)
    - Fibrous dysplasia
    - Metastases
    - Aggressive osteomyelitis
  • Osteosarcoma: Facts
    - Most common primary bone tumor in children and young adults
    - Occurs in metaphysis of long bones in 80% of cases 55% of cases occur around the knee
    - 20% of cases occur in flat bones and spine
    - Aggressive periosteal reaction with sunburst appearance
  • Classic Osteosarcoma: facts
    - Origin in metaphysis
    - Most common in long bones (70-80%) and especially around the knee
    - Usually has aggressive periosteal reaction with new bone formation
    - CT shows osteoid component of the tumor very nicely
  • Osteosarcoma: Facts
    - Most common primary bone tumor in childhood and young adulthood
    - 2nd most common primary bone tumor
    - High grade intramedullary osteosarcoma makes up 75% of cases
  • Clinical presentation

    - Lower back pain
    - Sensory loss
    - Gait disturbances
    - Bladder and bowel dysfunction
  • Extradural Sacral Myxopapillary Ependymoma: Factoids
    - Patients in 3rd or 4th decade
    - Slow, insidious onset
  • Differential Dx

    - Chordoma-age 60-70
    - Metastases-usually >40
    - Myeloma or plasmacytoma-age >40
    - Giant cell tumor
    - Aneurysmal bone cyst-age 10-20
    - Neurogenic tumor
  • Extradural Sacral Myxopapillary Ependymoma
    - Myxopapillary Ependymoma almost always occurs in the region corresponding to the filum terminale or cauda equina
    - May be extradural in the presacral space or within the sacrum
    - Although primarily suggesting a bone tumor on imaging a presacral mass is not uncommon
    - These are slow growing tumors with local recurrence common
  • Extradural Sacral Myxopapillary Ependymoma
    - Ependymomas represent 4-6% of primary CNS lesions
    - Ependymomas make up 63% of intraparenchymal lesions of the spinal cord
    - Myxopapillary ependymoma account for 25% of all ependymomas (most common type)
  • “Whole body MDCT leads to a significantly lower detection rate and staging in patients with multiple myeloma.” Whole Body MRI Versus Whole Body MDCT for Staging of Multiple Myeloma
    Baur-Melnyk A et al.
    AJR 2008; 190:1097-1104
All images on this site are © 2017 Elliot K. Fishman, MD.