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Rectal cancer staging with PET/MRI

Patient’s history

A 59 years old male patient presented with rectal bleeding and recently pathologically proven rectal adenocarcinoma. PET/MRI was performed for local rectal staging, nodal and metastatic workup.

Local staging: [T]

• Circumferential irregular mural thickening is seen implicating the mid and upper rectum where this mass lesion is measuring about 6.7 x 4.5 x3.5 cm. (Yellow arrows)
• It is infiltrating the muscularis propria with multiple sizable extra mural extension into the surrounding meso-rectum, reaching a thickness of about 23mm. (White arrows)
• Significant extra mural vascular invasion is seen.
• There is infiltration of the peritoneal reflection noted at the pelvis. (red arrows)
• The mass showed:
  • Significant restricted diffusion with mean ADC value of about 0.5×10-3 mm2 /sec.
  • Increased metabolic activity reaching 30 SUVmax.
  • Significant hyper-enhancement with pronounced increased K-trans value of 0.616, for the mass compared to 0.08, for the normal lower rectum.

Nodal staging: [N]

• Multiple enlarged hypermetabolic lymph nodes are noted at perirectal, presacral and right internal iliac regions. (Yellow arrows)
• The perirectal lymph nodes are seen inseparable from the meso-rectal fascia on both sides. (positive circumferential resection margin) (White arrows).

Distant Metastasis: [M]

• The liver shows multiple hypermetabolic and diffusion restricted bilobar focal lesions. (yellow arrows)

Overall staging:

• T4a, N2, M1.