Table of Contents
Abstract
Surgical exploration in patients with pancreatic or periampullary cancer is often performed without intraoperative image guidance. Although intraoperative ultrasound (IOUS) may enhance visualization during resection, this tool has not been investigated in detail until now. Objectives: The primary objective was to evaluate the impaсt of IOUS on the surgical strategy. Radicality of the resections and vascular contact were determined during operative assessmemt and compared with IOUS findings. Patients and Methods: Here, we performed a prospective cohort study to evaluate the effect of IOUS on surgical strategy and to evaluate whether vascular involvement and radicality of the resection could be correctly assessed with IOUS.
IOUS was performed by an experienced surgeon during surgical exploration in 38 consecutive procedures whiсh was сonduсted in the department of surgery, Theodor Bilharz Researсh Institute (TBRI) from 2016 to 2019 .eaсh patient;will undergo IOUS then the results compared with intra-operative assessmemt. Results: Overall, IOUS influenced surgical strategy in 61% of procedures. In 21 out of 27 malignant tumors, a radical resection was achieved (78%). Vascular contact was assessed correctly using IOUS in 89% compared with 74% of patients using preoperative imaging. Conclusion: IOUS can help the surgical team to assess the resectability and to visualize the tumor and possible vascular contact in real time during resection. IOUS may therefore increase the likelihood of achieving a radical resection.
Introduction
The prognosis for patients with pancreatic cancer who undergo surgery with curative intent depends largely on the ability to achieve a radical resection (Kim et al. 2016). Typically, preoperative computed tomography (CT) imaging is used to determine the local extent of the tumor (Ichikawa et al. 2006). Factors that determine local resectability include contact with surrounding structures, vascular involvement and the absence of distant metastases (Feldman and Gandhi 2016). To improve outcomes, neoadjuvant chemotherapy is often administered to patients who present with borderline-resectable or locally advanced tumors (Liao et al. 2017).
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However, neoadjuvant chemotherapy can complicate the ability to assess the resectability of the tumor using CT imaging, largely because of the difficulties associated with distinguishing between chemotherapy-induced fibrosis and viable tumor tissue (Donahue et al. 2011; Katz et al. 2012). Surgical treatment for pancreatic cancer generally begins with surgical exploration to identify occult metastases and to assess the tumor’s resectability. During this procedure, the surgeon must rely solely on visual inspection and palpation in order to distinguish between tumor and normal tissue. This can be challenging, particularly in the presence of peri-tumoral inflammation.
Moreover, in up to 60% of patients who undergo a resection of their pancreatic tumor, histologic microscopic assessment reveals tumor infiltration into the borders of the resected specimen, resulting in a high rate of local recurrence (Campbell et al. 2009; Ghaneh et al. 2017; Neoptolemos et al. 2017). On the other hand, approximately half the patients who underwent venous resection because of suspected tumor invasion were found to have no tumor infiltration based on a pathologic examination in the resected vascular patch (Giovinazzo et al. 2016). Given these factors, the current treatment is to perform high-risk surgery, despite a suboptimal success rate and the fact that resection is often performed without the benefit of intraoperative guidance and visualization. Ultrasound, mostly endoscopic, has gained an important role in diagnosing patients with a suspicion of pancreatic cancer and has the benefit of being able to perform fine needle aspirations during the same procedure (Iqbal et al. 2012).
Laparoscopic ultrasound can be performed during staging laparoscopy prior to surgical exploration (Allen et al. 2016). During surgery, intraoperative ultrasound (IOUS) can be useful in helping determine vascular involvement in patients with borderline-resectable pancreatic cancer (de Werra et al. 2015; D’Onofrio et al. 2007). By offering real-time imaging data, IOUS provides direct feedback regarding the lesion’s extent and vascular involvement. This information can then be used to guide the surgical strategy and approach. In addition, because it uses a high-frequency probe in direct contact with the organ, IOUS provides superior spatial resolution and contrast compared with CT and magnetic resonance imaging (MRI) (Sun et al. 2010). Although IOUS may be useful during surgical exploration and resection of pancreatic cancer, few studies have used this technique to assess tumor extension and subsequent IOUS-guided resection (Tamm et al. 2013).
A study by Kolesnik et al. (2015) retrospectively examined the effect of IOUS on surgical interventions, reporting that their surgical strategy changed because of IOUS in 30% of the patients, most of them owing to the detection of hepatic metastases. Except for this study, IOUS is not routinely applied during resections of pancreatic cancer, and the added value is scarcely described. Here, the benefits of performing IOUS with respect to surgical strategy in patients with pancreatic or a periampullary tumor undergoing surgical exploration was evaluated. In addition, the results of preoperative radiologic imaging, IOUS and pathologic evaluation of the resected specimen were compared.
Aim of the Work
The primary aim of this study to evaluate the impaсt of IOUS in сhanging the plan of management of radicality of the resection; therefore, their impact on the surgical strategy and/or any additional information obtained from EUS and IOUS was defined as follows: (i) no value, (ii) additional information regarding tumor localization, (iii) additional information regarding vascular contact or (iv) the ability to waive surgery. The secondary objective was to evaluate the assessment of vascular involvement; therefore, both the preoperative imaging results including CT and the IOUS assessment of vascular contact were compared with the operative examination, which is the current gold standard. The contact between the tumor and any vessel was evaluated, in particular, contact between the tumor and the superior mesenteric vein (SMV), including the portal vein (PV) and its confluence.
Patients In Theodor Bilharz Researсh Institute (TBRI), preoperative radiologic imaging was performed on all patients with a suspect lesion in the pancreas. A CT scan was obtained for all patients. The patients were evaluated by the multidisciplinary pancreatic team in order to determine whether surgery was a treatment option. In patients who went on for an exploratory laparotomy, IOUS was performed. In this study, consecutive patients who underwent surgical exploratory laparotomies for pancreatic or periampullary cancers (including duodenal, distal bile duct or ampulla of Vater cancers) at the TBRI from June 2016 through June 2019 were included. In this study, only the impact of IOUS compared with preoperative investigation including CT and intraoperative assessement were evaluated, therefore, the need for informed consent by the Medical Ethics Committee of the TBRI was taken.
Description of different modalities Preoperative imaging: – The preoperative CT scans were acquired using an Aquilion ONE 160-detector row helical CT (Toshiba Medical Systems Europe, Zoetermeer, the Netherlands). Intravenous contrast (Ultravist-370, Bayer Australia Ltd, Pymble, Australia) was administered with automatic power injection prior to obtaining the scan. Axial, coronal and sagittal slices were obtained during the pancreatic phase (20 s after injection) and during the portal venous phase (50 s after injection). Evaluation of the preoperative imaging was initially performed by a specialized abdominal radiologist.
As regard IOUS: The IOUS machine is a linear real-time mode-B ultrasound using high frequency (5 and 7.5 MHz) sterile probes of different shapes. A lower frequency, 5 MHz, used for a larger, steatotic, or cirrhotic liver. The machine can be adjusted by the operating room nurse in the presence of a radiologist.
Scanning technique for malignant pancreatic operations
The diagnostic approach for tumors of the bile ducts & pancreas consists mainly in determining the local spread of these tumors, discovery of hepatic metastases, invaded lymph nodes and vascular elements.
Begin contact scanning on the anterior liver surface and start the scan by identifying the intrahepatic vasculature. Find the junction of the three hepatic veins with the vena cava at the superior most portion of the liver “rabbit ears”, each hepatic vein is followed peripherally to its terminal branches. Next, reevaluate each vein in the longitudinal (sagittal) plane.
A typical view of the hepatic hilum is acquired by contact scanning along the inferior aspect of the liver to the patient’s right of the falciform ligament in the transverse plane. The bifurcation of the portal vein is seen just distal to the termination of the main portal vein.
The systemic survey of the hepatic parenchyma follows next, seeking evaluation for diffuse and focal abnormalities
Lymph node invasion in our experience, we found that no morphologic criteria are available to establish the difference between inflammatory and neoplastic lymph nodes.
Then, the pancreas can be explored through the adjacent structures of the stomach, duodenum. and gastro-cholic ligament, or by placing the probe directly on the surface of the gland after incision of the gastro-cholic ligament.
Disappearance of the interface between the tumor and the external aspect of the venous wall, intraluminal tumoral invasion of the vessel or presence of thrombosis & tumor mass shown as a filling of the lumen, are the strict criteria of vascular involvement.
The superior mesenteric vein appears surrounded by the uncinate process. 3-5 mm lateral to this and below the vein runs the superior mesenteric artery (between vein and aorta). In this area the pancreas is less, thick, being about 1.2-1.7 cm. On transverse scan the splenic vein appears very clearly as it courses the length of the body to the tail of the pancreas.
Pancreatic carcinoma presents as a heterogeneous, poorly echoic mass with irregular contours.
If starting with diagnostic laparoscopy
- Through the epigastric port, Systematic scanning of the liver should start with identification of standard landmarks and of the liver parenchyma.
- It can also be useful to position the probe on the underside of the liver, particularly on the right lobe. Visualisation of the portal structures can be aided by inserting the probe through the infraumbilical port and placing it on the hepatoduodenal ligament.
- Then, the pancreas can be explored through the adjacent structures After complete US examination the procedure was completed whatever the result of the IOUS was, according to preoperative plan & real time exploration & dissection.
Statistical analysis
Statistics Assuming that the surgical strategy would be changed in >30% of the patients because of the IOUS assessment, 38 patients should be included. A sample size of 38 patients achieves 80% power using the two sided McNemar test with a significance level of 0.05. Differences between correct assessment of vascular contact between preoperative imaging and IOUS were assessed with a McNemar test.
Patient characteristics during the study period, IOUS was performed in 38 surgical explorations (Table 1). The research aimed to assess the impact of IOUS on surgical strategy, comparing preoperative imaging correlation (CT), IOUS and operational findings of vascular assessments and resectability.
Vascular contact was suspected on nine preoperative scans and vascular involvement on one scan. Vascular contact could not be determined from four preoperative scans (13%) because of the isodense appearance on the scans. Twenty-seven malignant tumors resected.During three explorations, resection was abandoned because of irresectable disease.
Among 38 patients (20 male, 18 female) with mean age 57y dragged in our study, all patients were subjected to pre CT, 2 patients have been exposed to a laparoscopic intraoperative ultrasound (LIOUS); 23 patients have been exposed to an intraoperative ultrasound (open method) (IOUS). In 85% of cases the average value of CEA and CA19.9 were elevated.
- Among 38 patients in our study: all patients had obstructive jaundice; 35 of them suffered of typical pancreatic pain. Actually in Our clinical records, after the performance of IOUS exam, 23 patients were eligible to perform a Whipple operation. Three patients exposed to LIOUS then converted to open. Complete tumor resection done in 23 patients, failed resection in 2 patients was: (one patient) due to vascular invasion and the other one due to direct invasion to peritoneal carcinosis, So 45 % was the co-ordinance with pre-operative diagnosis.
- The preoperative diagnosis performed with CT failed to detect 20% (5 patients) with irresectable tumor invasion, detect 22 patients with enlarged suspected loco-regional lymph nodes and one patient with para-aortic LNs. In 100 % (38 patients) IOUS can detect the tumor, 21 patients with enlarged suspected loco-regional lymph nodes and 2 patients with para-aortic LNs (The size of lymph node greater than 1cm, hypoechoic echogenicity, distinct margins, and round shape have been proposed as the criteria of metastatic lymph nodes).
- The IOUS detect 5 (20 %) patients with local or vascular invasion (with 88.9% specificity & 100.0% sensitivity). while CT detect 5 (20 %) patients with local or vascular invasion (with 66.7% specificity & 100.0% sensitivity).
- Average for The Mean time for IOUS procedure was 16.8421 + 4.77567 min. CT procedure was 25.0000+ .00000 min.The Mean time for the whole operation was 6.7h ± 54 min.
In four patients there was a tumoral encroachment of the portal vein but with line of cleavage; one patients showed a tumoral encroachment of IVC; 2 of them showed a tumoral encroachment of the superior mesenteric vein with signs of omental cancer; 23 patients had some central positive loco-regional lymph-nodes which could be detected by CT exam.
