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CT after Pancreaticoduodenectomy with Portal Vein and/or Superior Mesenteric Vein Reconstruction: Review of Current Surgical Techniques and Associated Post Surgical Imaging Findings

Elliot K. Fishman, M.D.

The Russell H. Morgan Department of Radiology and Radiological Science
The Johns Hopkins Medical Institutions
Baltimore, Maryland

Introduction

Pancreatic adenocarcinoma is the fourth leading cause of all cancer-related mortality in the US and continues to carry a poor prognosis, with a 5-year survival rate of approximately 7%. (1)
Complete surgical resection is currently the only curative option, despite advances in chemotherapy and radiation regimens.
Surgical techniques have been evolving in the past decade in order to offer patients with increasing degrees of vascular involvement a chance at a surgical cure.
Current surgical techniques include several methods of resecting and reconstructing the PV and SMV in order to completely remove tumors with venous involvement.

Purpose

To review the current venous reconstruction techniques being performed in conjunction with pancreaticoduodenectomy
To establish patterns of findings on post operative CT that are associated with venous reconstruction techniques
To distinguish post venous reconstruction CT appearances from recurrent disease

Materials and Methods: Patients

Approval for this retrospective review was obtained from our Institutional Review Board and a waiver of informed consent was provided for medical record and CT review.
We retrospectively reviewed our database of all patients who underwent pancreaticoduodenectomy (PD) with concurrent PV-SMV reconstruction (PVR) from 2004-2014 at our institution.
The database includes patients with planned venous resection and reconstruction for venous tumor involvement, and patients who underwent venous reconstruction to repair an intra-operative injury during a PD procedure.

Materials and Methods: Patients

Inclusion criteria:
- Contrast enhanced CT available within 60 days post-op
- Pathologic R0 or R1 resection
Recurrent malignancy is highly unusual in the immediate post-operative period in patients for whom a complete surgical resection has been achieved.
Therefore we considered the CT findings in this limited patient population to represent the range of post-operative imaging appearances, without the presence of confounding residual or recurrent tumor.

Materials and Methods: Patients

70 patients in our database met the inclusion criteria.
- Pathologic diagnoses:
  - Pancreatic ductal adenocarcinoma - 71% (50)
  - Pancreatic neuroendocrine tumor – 6% (4)
  - Cholangiocarcinoma – 6% (4)
  - Gallbladder carcinoma – 3% (2)
  - Other – 14% (10) - benign bile duct stricture, adenosquamous carcinoma, pancreatic intraepithelial neoplasia, mucocele, SPEN, solitary fibroid tumor, undifferentiated carcinoma, chronic pancreatitis, ampullary carcinoma, serous cystic neoplasm
- Average number of days between surgery and CT follow-up: 17
- Males: 53% (37)
- Females: 47% (33)

Materials and Methods: Post-PD CT protocol

All post-PD patients at our institution are followed with dual phase pancreatic protocol CT
- Dual-phase technique
  - Nonionic IV contrast material is injected at 3-5 mL/s
  - Arterial phase images acquired at 30 sec after contrast and portal venous phase images acquired at about 1 minute.
  - Water is used as a neutral oral contrast
- Multiplanar reconstruction
  - Coronal and sagittal planes automatically created at CT console
  - Coronal plane often best for evaluating PV-SMV changes
- 3D postprocessing
  - Maximum-intensity-projection (MIP)
    - Projection of the highest-attenuation voxels in a dataset into a 2D image
    - MIP images are most valuable for evaluation of mesenteric vasculature
  - Volume rendered images
    - Computer algorithm assigns specific color and transparency to each voxel based on attenuation characteristics
    - Data presented in interactive 3D display

Materials and Methods: Surgical Analysis

Reconstruction of tangential venous resection or repair of tear:
- For tumor adherent to a small segment of the PV-SMV, the involved portion of the vein is removed by tangential resection and either a primary closure (longitudinal or transverse) or a secondary closure with a vein patch is performed.
- Primary venorrhaphy can also be performed for repair of intra-operative venous tears.

Materials and Methods: Surgical Analysis

Reconstruction of segmental venous resection:
- For tumor involving a long segment of the PV-SMV, or for circumferential venous tumor involvement, the involved portion of the vein is removed by segmental resection and either a primary end-to-end anastomosis or a secondary closure with an interposition graft is performed.

Results – PVR techniques

Primary reconstruction (without the use of a conduit) was performed in 90% of the cases.

Interposition grafts most commonly included the IJ or renal vein. PTFE grafts are rarely used because of association with thrombosis.

Results – PVR techniques

PV-SMV findings: Four patterns of PV-SMV changes are seen on CT after PVR

Results: Patterns of post-op CT findings after PVR

Perivenous findings: Two patterns of perivenous changes are seen on CT after PVR

Results: Patterns of post-op CT findings after PVR

PV-SMV: Venous narrowing on CT after PVR

PVR procedures were associated with post op PV-SMV narrowing in 84% of patients, ranging from mild to severe.

PV-SMV: Venous narrowing on CT after PVR

PV-SMV: Venous thrombosis on CT after PVR

Occlusive thrombosis was seen in 9% of cases after PVR.

PV-SMV: Venous thrombosis on CT after PVR

Perivenous space: Perivenous ST thickening on CT after PVR

Perivenous space: Induration/inflammation/fluid on CT after PVR

Perivenous space: CT Findings after PVR

Mass-like perivenous soft tissue thickening was seen in 19% of patients after PVR, and was limited to patients with primary reconstructions, however, the number of cases of graft reconstruction was small in our sample.

Perivenous space: CT Findings after PVR

Results – Summary

The CT appearance of the PV-SMV after PVR includes four patterns

Results – Summary

The PV-SMV patterns are not mutually exclusive; some patients had findings in more than one category.

Results – Summary

The CT appearance of the PV-SMV after PVR includes four patterns

Results – Summary

The PV-SMV patterns are not mutually exclusive; some patients had findings in more than one category.

91% of the patients had PV-SMV changes that can also be seen with recurrent pancreatic cancer

Results – Summary

The CT appearance of the perivenous space after PVR includes two patterns:

Results – Summary

Results – Summary

The CT appearance of the perivenous space after PVR includes two patterns:

Results – Summary

Perivenous soft tissue thickening mimics the appearance of recurrent or residual pancreatic cancer.

Conclusions

Considerable overlap exists between the post-operative appearance of the PV-SMV and surrounding tissues after PVR, and between the appearance of recurrent pancreatic cancer.

Post-Op PVR

PV-SMV findings
- Concentric narrowing
- Eccentric narrowing/defect
- Thrombosis
- Venous configuration changes
Perivenous findings
- Perivenous soft tissue thickening
- Perivenous induration/inflammation/fluid

Recurrent pancreatic cancer

PV-SMV findings
- Concentric narrowing
- Eccentric narrowing/defect
- Thrombosis
Perivenous findings
- Perivenous soft tissue thickening

Conclusions

Venous resections and reconstructions are becoming increasingly more common components of pancreaticoduodenectomy procedures.
Accurate interpretation of CT for post-op pancreatic cancer patients must include a detailed knowledge of the surgical history in order to avoid the pitfall of mistaking PVR associated findings with recurrent cancer. A venous reconstruction procedure may be an unplanned component of a pancreaticoduodenectomy surgery.
Familiarity with the commonly seen patterns of the PV-SMV and perivenous space after PVR can help to avoid over-calling recurrent pancreatic cancer in this patient population.

Clinical Application

Differentiating post-PVR CT findings from recurrent pancreatic cancer

The spectrum of CT findings after PD with PVR commonly includes aggressive appearances.

Avoid the pitfall of overcalling recurrent local pancreatic cancer.

Clinical Application

Clinical Application

Determine surgical details, beyond “Whipple.”
Note that a PD might include an unplanned PVR.

Clinical Application

Determine surgical details, beyond “Whipple.”
Note that a PD might include an unplanned PVR.

Establish baseline post-operative pattern.
Use coronal images to define post-op PV-SMV configuration.
Compare to post-op baseline CT to assess for changes over time.

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