A 62-year-old woman undergoes staging workup for biopsy-proven pancreatic adenocarcinoma of the body. Contrast-enhanced CT shows a 3.5 cm hypodense lesion with no distant metastases. The clinician needs to assess for vascular invasion (superior mesenteric vein and artery involvement) and distant lymph node metastases to determine resectability. Which investigation is most appropriate for detailed vascular assessment and staging?