1.Importance of X-ray plain film?
X-ray plain film is the first choice and important examination tool in bone tumor diagnosis. According to the location of lesion, type of bone destruction, integrity of bone cortex, edge of lesion, presence or absence of sclerotic border, presence or absence of residual bone in lesion, calcification of tumor cartilage, tumor bone formation, presence or absence of periosteal reaction and its type, change of soft tissue around the lesion area and other signs, it can suggest tumor or non-tumor, benign or malignant, primary and secondary lesions. It can indicate tumor or non-tumor, benign or malignant, primary and secondary lesions. With the development of digital technology, ordinary X-ray plain film has been replaced by CR and DR. The improvement of X-ray plain film quality allows us to obtain more and more accurate information to arrive at an accurate diagnosis, and as the first choice examination method for bone tumor, we should pay attention to it, and we should not neglect the most basic examination because of the emergence of CT, MRI and other large examinations.
2.The role of CT?
CT is a tomography scan of lesion, which can clearly show the location, scope and relationship with muscle, organ, nerve and blood vessel of tumor, and can clearly and unambiguously show the internal structure of tumor, some tiny lesions or early malignant bone tumor can be shown as normal on X-ray, while CT is sensitive to tiny bone destruction, the scope of lesion involvement and the density value inside bone destruction, and can show the internal structure of tumor earlier than plain film. It can show the extent of bone cortex and joint surface destruction, clarify the extra-bony and intramedullary invasion, and detect soft tissue masses at an early stage.
CT intensification scan refers to the rapid injection of contrast agent through the vein with a high-pressure syringe and then rapid and continuous scanning to observe the changes of blood supply in the arterial and venous phases of the lesion and to increase the contrast between the lesion and the surrounding normal tissues to facilitate the detection of the lesion and differential diagnosis. CT scan has become a routine examination for bone tumors.
3.What is the role of MRI?
MRI is what we usually call magnetic resonance imaging. MRI is more sensitive than X-ray plain film and CT in detecting bone tumor, especially in observing the infiltration range of lesion, the relationship between soft tissue mass and blood vessel, the range of muscle edema and the way of tumor expansion, but its display of bone cortex and calcification is poor. Therefore, MRI is mainly used to show the relationship between tumor and surrounding tissues, to clarify the size and invasion range of tumor, to distinguish the tissue components in the lesion area, to determine the extent of intramedullary infiltration of tumor and to judge the relationship between tumor and surrounding important blood vessels and nerves, which is very important for preoperative planning. In addition, MRI is also used to observe and evaluate the efficacy of radiotherapy, chemotherapy and surgery of bone tumor, and to detect the comorbidity and recurrence of tumor and metastasis at an early stage.
4.What is the role of ultrasound?
Under normal physiological conditions, ultrasound is almost completely reflected on the surface of bone, so it is difficult to penetrate bone tissue and obtain images of the deep surface of bone. Ultrasound can more correctly estimate the location, extent and size of tumors, and can indicate whether soft tissue masses are destroying the bone cortex. Ultrasonography is very important for the diagnosis of soft tissue tumors, especially for the masses adjacent to joints. Ultrasonography can be used to understand the size and depth of soft tissue masses, whether the tumor is cystic or solid, and whether the tumor is rich in blood flow, which can help to determine the benignity and malignancy of soft tissue tumors. Therefore, ultrasound is most widely used in preoperative diagnosis and postoperative follow-up of soft tissue tumors.
5.What is the role of whole body bone scan?
Isotope bone scan is to detect metabolic abnormalities of bone tissue by radionuclide, so it can show certain bone tissue lesions before the abnormalities appear in X-ray and CT scan. In addition, bone scan can assist other imaging examinations to clarify the clinical diagnosis. The sensitivity of bone scan is very high, but the disadvantage is that the specificity is not high, the detection of lesions is accurate in localization, but the characterization is difficult, and there is some difficulty in distinguishing tumorigenic and non-tumorigenic diseases. Bone tumors, arthritis, bone infarcts, osteomyelitis, orthopedic surgery and fractures can all show radioactive concentrations. Isotope bone scans are primarily used to screen for multiple bone lesions. It is only a screening and cannot be used as a qualitative diagnosis.
6.What is the role of angiography?
Digital subtraction angiography (DSA) is a new medical imaging diagnostic technique used in clinical practice in recent years to detect the vascular distribution of bone tumors, the main vascular structures of lesions, and to show the abnormal changes of normal vessels and the status of abnormal vessels. The purpose of angiography is, on the one hand, to show the blood supply vessels of tumor and the extent of tumor invasion, such as sacrococcygeal tumor, which can be supplied by one internal iliac artery or bilateral internal iliac arteries, and some of them have lumbar artery or median sacral artery in addition to bilateral internal iliac arteries. On the other hand, the nature and malignancy of the tumor can be accurately judged based on the performance of tumor vessels and blood supply, thus providing an objective basis for the formulation of treatment plan and preparation for surgical resection.
7.What is the role of PET-CT?
PET-CT works by putting PET (Positron Emission Tomography) and CT together, and the data obtained is not only used to reconstruct the CT image, but also the PET image. The image displayed is the result of the fusion of the two images, i.e. the metabolic image of the cells and the anatomical location where they are located.
PET-CT is a combination of functional and anatomical imaging, and its role is first and foremost in the diagnosis of diseases, especially in the diagnosis of tumors. The tracer 18 F-FDG is injected into the body instead of deoxyglucose, and the glucose metabolism in the target area is observed to diagnose the nature of the tumor based on the fact that malignant tumors have high metabolism. PET-CT is especially advantageous for sites with complex anatomical parts and insignificant density contrast. PET-CT is an advanced examination tool with non-invasive characteristics and can show the metabolic situation of all parts of the body, which will definitely play a greater role in the diagnosis and treatment of bone and soft tissue tumors and bone metastasis cancer.
Due to the existence of false positives and false negatives, the results should be determined comprehensively.
8.How to choose the appropriate examination?
Patients need to do many related examinations, and how to choose the appropriate one is a great concern for patients and their families. Each test has its advantages and disadvantages and indications. No one test can replace other tests, and a comprehensive examination and evaluation of bone tumor requires multiple tests to complement each other and respond to each other’s evidence. Based on the medical history provided by the patient, the clinician first conducts a detailed physical examination before prescribing the corresponding tests. The first choice is X-ray plain film for bone lesions, ultrasound for soft tissue masses, enhanced CT has become a routine examination for bone tumors, if malignancy is suspected then pulmonary CT, abdominal ultrasound, whole body bone scan to exclude metastases. MRI, PET-CT are not routine and should be performed as needed.
9.Can we rely on laboratory tests to find out bone tumor?
The diagnosis of bone tumor is a combination of clinical manifestation, imaging and pathology, and the diagnosis of bone tumor cannot be made by laboratory test alone. However, laboratory tests still have an important role in the diagnosis and treatment of bone tumors. Some patients with osteosarcoma have elevated alkaline phosphatase (AKP), and alkaline phosphatase (AKP) and lactate dehydrogenase (LDH) are important for assessing the prognosis of patients, and AKP levels are used to detect recurrence of osteosarcoma and bone metastasis at an early stage. Malignant bone tumors often present with anemia and decreased hematocrit in advanced stages of wasting manifestations. Multiple myeloma tends to have rapid hematocrit, high globulin, and A/G inversion. Increased blood calcium may be a sign of bone metastatic cancer. psa is an indicator of bone metastasis from prostate cancer.