What imaging studies are recommended for the diagnosis and staging of gastric lymphoma?

Imaging for Gastric Lymphoma: Diagnosis and Staging

For gastric lymphoma, the essential imaging workup includes contrast-enhanced CT of chest, abdomen, and pelvis as the primary staging modality, combined with endoscopic ultrasound (EUS) for locoregional assessment of gastric wall infiltration and perigastric lymph nodes 1, 2.

Primary Imaging Studies

Computed Tomography (CT)

• Contrast-enhanced CT of thorax, abdomen, and pelvis is the cornerstone imaging modality for staging gastric lymphoma 1, 2
• Plain CT scans without contrast are inadequate and should not be used
• CT effectively identifies:
  • Lymph node involvement (nodes with short-axis diameter ≥1.5 cm are considered pathologic)
  • Distant metastases (liver, lung, peritoneal disease)
  • Overall disease burden and distribution
• For optimal gastric evaluation, patients should drink 500-700 mL of water to distend the gastric cavity 3
• CT demonstrates gastric wall thickening, ulcerations (43% of cases), masses (36%), and rugal thickening (21%) 3

Endoscopic Ultrasound (EUS)

• EUS is highly valuable for locoregional staging and must be integrated into the standard staging procedure 4, 5
• EUS specifically assesses:
  • Depth of gastric wall infiltration (T-stage)
  • Perigastric lymph node involvement (N-stage)
  • Extent of tumor within the gastric wall layers
• EUS provides important prognostic information regarding response to Helicobacter pylori eradication therapy 4
• Should be performed at qualified centers with experienced operators 1

Important caveat: EUS has limited diagnostic specificity—in one study, 40% of cases suspected to be gastric cancer on EUS were actually lymphoma, highlighting that EUS is better for staging than initial diagnosis 6

Additional Imaging Considerations

PET-CT

• PET-CT is recommended for staging of FDG-avid lymphomas (most non-Hodgkin lymphomas except marginal zone lymphomas unless aggressive transformation is suspected) 2
• May improve detection of involved lymph nodes and metastatic disease beyond conventional CT
• Less useful for gastric MALT lymphoma, which is often not highly FDG-avid

MRI

• Reserved as an alternative when CT contrast is contraindicated 1
• Not routinely recommended as first-line imaging for gastric lymphoma

Staging Algorithm

Follow this systematic approach:

1. Initial endoscopy with multiple biopsies from all gastric regions, duodenum, and gastroesophageal junction—this establishes the diagnosis 1

2. Contrast-enhanced CT chest/abdomen/pelvis—primary staging tool for nodal and distant disease 1, 2

3. EUS of upper GI tract—for locoregional T and N staging 1, 4

4. Bone marrow biopsy—recommended as part of complete staging workup 1

5. Consider PET-CT if high-grade transformation is suspected or for non-MALT lymphoma subtypes 2

Critical Pitfalls to Avoid

• Do not rely on plain CT without contrast—it provides inadequate information for staging
• Do not use EUS alone for diagnosis—its morphologic appearance can mimic gastric cancer; always confirm with histopathology 6
• Do not skip chest CT—thoracic involvement must be evaluated even for gastric primary disease 1
• EUS has limited value for monitoring treatment response to chemotherapy or radiation and should not be used routinely for follow-up 4

Staging Classification

Use the Lugano staging system (widely accepted) or the Paris staging system (better describes depth of gastric wall involvement, which predicts response to H. pylori eradication) 1. The imaging findings should be integrated with endoscopic findings and bone marrow results to assign the final stage.