Common imaging examination methods for melanoma in clinical practice

Malignant melanoma is a rare malignant tumor. The annual incidence rate in Queensland, Australia is relatively high, reaching 16/100,000 people. Blacks and Asians rarely suffer from this disease. Among them, the 5-year survival rate of freckle melanoma is as high as 80%; the 5-year survival rate of patients with nodular melanoma who have been treated before metastasis is about 50%.

1. X-ray examination: Through X-ray examination, chest X-ray examination should be performed for possible asymptomatic lung metastasis. If metastasis is indicated, lung tomography or CT scan should be used to confirm it.

2. Ultrasound imaging: It helps to understand the location and range of melanoma and determine the nature of the shadow. The success rate of puncture biopsy under ultrasound guidance can reach 80% to 90%.

3. Magnetic resonance imaging (MRI): MRI can display high-definition images of soft tissue structures around bones, chest and abdominal organs, including the lungs, liver, spleen, pancreas and blood vessels, so that doctors can diagnose tumors more accurately. MRI can not only improve the accuracy and high contrast of images, but also reduce blur and defects, provide optimized anatomical images, and facilitate accurate detection of melanoma.

4. Computerized tomography (CT): A CT scan of the head should be performed for suspected brain metastasis. However, CT has low sensitivity in detecting normal-sized lymph nodes infiltrated by tumors and small abdominal metastases. The clinical value of judging whether malignant transformation has occurred based solely on the size of lymph nodes on CT is limited, and CT cannot detect all parts of the body at the same time.

5. Positron emission tomography (PET): The basic principle is to reflect the changes and differences in the utilization of glucose by tissues. The sensitivity and specificity of PET in diagnosing melanoma are higher than those of CT. A single whole-body PET scan can also detect new lesions and lymph node metastases in multiple organ systems throughout the body. However, PET cannot provide accurate anatomical localization information of metastatic lesions, so it needs to be supplemented by other imaging methods.