Pancreatic cancer ultrasound

The appearance of pancreatic cancer relative to normal pancreatic tissue may be hypoechoic, isoechoic or hyperechoic on transabdominal ultrasound. An ill defined hypoechoic mass is seen infiltrating into a bright pancreatic parenchyma in majority of the cases. This may be accompanied by pancreatic and biliary duct dilatation. Endoscopic Ultrasound (EUS) has a higher resolution than transabdominal ultrasound, due to the small distance between the endoscope and pancreas through the wall of the duodenum. EUS plays an important role in the preoperative staging of pancreatic cancer and also has a high efficacy in the detection of tumors smaller than 2 cm, for local T and N staging, and prediction of vascular invasion. Moreover, EUS-guided fine needle aspiration biopsy (FNA) is the best modality for obtaining a tissue diagnosis.

• Pancreatic cancer has a variable appearance on USG.
• The appearance relative to normal pancreatic tissue may be:^[1]
  •  Hypoechoic
  •  Isoechoic
  • Hyperechoic
• In majority of the cases, an ill defined hypoechoic mass is seen infiltrating into a bright pancreatic parenchyma. Ascites may also be visible.
• Pancreatic and biliary duct dilatation is seen in case of carcinoma of the head of pancreas (Double duct sign ^[2])

• The drawbacks of transabdominal USG are as follows:^[3]
  • USG does not clearly demarcate
    • Lymphadenopathy
    • Tumor margins
    • The relation of the tumor to vessels around the pancreas

• USG has lower sensitivity as compared to other modalities in the detection of pancreatic cancer smaller than 2 cm.
• For pancreatic cancer detection:
  •  Sensitivity=  70%
  •  Specificity= 95%

Advantages of EUS are as follows:^[4][5]

• EUS has a high efficacy in the detection of tumors smaller than 2 cm, for local T and N staging, and prediction of vascular invasion.
• EUS has a higher resolution than transabdominal ultrasound, due to the small distance between the endoscope and pancreas through the wall of the duodenum.
• EUS has a role in the preoperative staging of pancreatic cancer particularly in cases where CT evaluation suggests equivocal findings.
•  EUS-guided fine needle aspiration biopsy (FNA) is the best modality for obtaining a tissue diagnosis.

Drawbacks of EUS are as follows: ^[6]

• EUS is inferior to CT for evaluation of distant metastasis.

• EUS is also operator-dependent; hence its value varies with physician expertise.

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