Stomach cancer, also known as gastric cancer, is a disease where abnormal cells grow uncontrollably in the stomach lining. It represents a significant global health concern, ranking as the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. Medical imaging plays a central role in the detection, diagnosis, and ongoing management of this condition, providing healthcare professionals with insights into the disease’s presence and extent.
Imaging Techniques for Stomach Cancer
Several imaging techniques are used to detect and evaluate stomach cancer. Endoscopy, particularly upper endoscopy with biopsy, is a primary method. During an upper endoscopy, a thin, flexible tube with a camera is inserted through the mouth into the esophagus, stomach, and the upper small intestine. This allows for direct visual inspection of the stomach lining and collection of tissue samples (biopsies) from suspicious areas for laboratory analysis.
Computed Tomography (CT) scans are widely used and provide detailed, cross-sectional images of the stomach and surrounding structures. Multi-detector CT (MDCT) scanners offer faster scanning and allow for multiplanar and 3D image reconstructions. Magnetic Resonance Imaging (MRI) uses magnetic fields and radio waves to generate detailed soft tissue images, with good contrast between healthy and diseased tissues. While not as frequently used as CT for initial staging, MRI can be helpful for specific situations like detecting liver metastases.
Positron Emission Tomography (PET) scans involve injecting a small amount of radioactive sugar, which cancer cells tend to absorb more actively. A special camera then identifies areas where this sugar accumulates, detecting cancer spread throughout the body. Often, PET scans are combined with CT scans (PET/CT) to provide both metabolic activity and anatomical detail. A barium swallow, also known as an upper GI series, involves drinking a liquid containing barium, which coats the esophagus and stomach, making them visible on X-rays. This older technique can identify abnormalities, though it is used less frequently than endoscopy because it does not allow for biopsies.
What Stomach Cancer Images Reveal
When clinicians review stomach cancer images, they look for specific visual characteristics that indicate the disease’s presence and extent. On endoscopy, a tumor may appear as a visible mass, an ulcer, or an area of irregular or thickened mucosa. Early gastric cancers, limited to the inner layers, might present as small, circumscribed thickenings, sometimes with ulceration. Advanced cancers, which extend deeper into the stomach wall, may manifest as polypoid (mushroom-like), ulcerating, or diffusely infiltrating lesions, sometimes resembling a “leather bottle” appearance (linitis plastica).
On CT scans, stomach cancer often disrupts the normal multilayered pattern of the gastric wall, consisting of distinct inner and outer layers. A focal thickening of the stomach wall greater than 5 millimeters in a well-expanded stomach is considered a suspicious finding. These images also reveal associated features like increased enhancement of the stomach wall after contrast administration, indicating abnormal blood flow to the tumor. Spread to nearby lymph nodes appears as enlarged nodes, while distant metastases might be seen as new growths in organs like the liver or fluid accumulation in the abdomen, suggesting peritoneal involvement.
MRI, with its superior soft tissue contrast, provides detailed views of tumor invasion into the stomach wall and surrounding tissues. It shows subtle differences in tissue characteristics that might not be as clear on other imaging types. For instance, MRI better demonstrates the fat plane between the stomach and adjacent organs, indicating whether the tumor has invaded these structures. PET scans, by highlighting areas of increased metabolic activity, pinpoints cancerous lesions that might not be structurally obvious on CT or MRI, particularly in cases of widespread disease.
The Role of Imaging in Diagnosis and Treatment Planning
Imaging plays a comprehensive role in managing stomach cancer, influencing every stage of patient care, from initial detection through treatment. After a suspicious area is identified, imaging guides biopsy procedures, ensuring tissue samples are collected from the most representative parts of the lesion for definitive diagnosis. Once cancer is confirmed, imaging becomes central to staging, determining the tumor’s size, its spread to nearby lymph nodes, and the presence of distant metastases.
The TNM staging system, which classifies the primary tumor (T), regional lymph nodes (N), and distant metastasis (M), relies heavily on imaging findings. CT scans are particularly effective for assessing the extent of the primary tumor (T stage) and detecting distant metastases (M stage). Endoscopic ultrasound (EUS) is often used for local staging, especially for early-stage cancers, due to its ability to visualize the layers of the stomach wall and nearby lymph nodes with high accuracy for T staging.
Information from these images directly informs treatment planning. For early-stage cancers confined to the stomach lining, endoscopic removal might be an option. For more advanced diseases, imaging guides decisions regarding surgical resection, indicating the required extent of stomach or lymph node removal. Imaging also determines if chemotherapy or radiation therapy should be administered before surgery (neoadjuvant therapy) to shrink the tumor, or after surgery (adjuvant therapy) to eliminate residual cancer cells. Imaging is also used to monitor the effectiveness of these treatments, showing whether the tumor is shrinking or if the cancer has recurred.
Preparing for Imaging Tests
Preparing for stomach imaging tests involves specific instructions for clear and accurate results. For many imaging procedures, such as CT scans with contrast dye, patients are asked to fast from solid foods for several hours, often three hours, before the test. Clear liquids, like water, black decaffeinated tea or coffee, and clear broth, are permitted. Patients should discuss any current medications with their healthcare provider, as some may need adjustment or temporary stoppage.
For endoscopic procedures like upper endoscopy, fasting for a longer period (6 to 8 hours) is required to ensure the stomach is empty. Patients may also receive a local anesthetic spray to numb the throat or sedation to help them relax and minimize discomfort. For tests involving contrast agents, such as CT or MRI, patients may receive the dye orally or through an intravenous injection. Patients should remove any metal objects or jewelry that could interfere with imaging equipment, especially for MRI scans due to strong magnetic fields. Always consult the healthcare provider for specific instructions tailored to the individual test and medical history.