Intraoperative Ultrasound as a Screening Modality for the Detection of Liver Metastases during Resection of Primary Colorectal Cancer - A Systematic Review

Ultrasound guidance in navigated liver surgery: toward deep-learning enhanced compensation of deformation and organ motion

PURPOSE

Accuracy of image-guided liver surgery is challenged by deformation of the liver during the procedure. This study aims at improving navigation accuracy by using intraoperative deep learning segmentation and nonrigid registration of hepatic vasculature from ultrasound (US) images to compensate for changes in liver position and deformation.

METHODS

This was a single-center prospective study of patients with liver metastases from any origin. Electromagnetic tracking was used to follow US and liver movement. A preoperative 3D model of the liver, including liver lesions, and hepatic and portal vasculature, was registered with the intraoperative organ position. Hepatic vasculature was segmented using a reduced 3D U-Net and registered to preoperative imaging after initial alignment followed by nonrigid registration. Accuracy was assessed as Euclidean distance between the tumor center imaged in the intraoperative US and the registered preoperative image.

RESULTS

Median target registration error (TRE) after initial alignment was 11.6 mm in 25 procedures and improved to 6.9 mm after nonrigid registration (p = 0.0076). The number of TREs above 10 mm halved from 16 to 8 after nonrigid registration. In 9 cases, registration was performed twice after failure of the first attempt. The first registration cycle was completed in median 11 min (8:00-18:45 min) and a second in 5 min (2:30-10:20 min).

CONCLUSION

This novel registration workflow using automatic vascular detection and nonrigid registration allows to accurately localize liver lesions. Further automation in the workflow is required in initial alignment and classification accuracy.

Usefulness of intraoperative ultrasound examination for laparoscopic right-side colon cancer surgery: a propensity score-matched study

Complete mesocolic excision (CME) with central vascular ligation (CVL) in laparoscopic surgery for right-sided colon cancer (RSCC) requires a precise understanding of the vascular anatomy. The efficacy of intraoperative ultrasound (IUS) in the identification of blood vessels for RSCC surgery was not evaluated. The aim of this study was to compare the intraoperative and short-term outcomes of CME with CVL with or without IUS by laparoscopic surgery for RSCC. We performed IUS on 26 patients of RSCC and compared with a total of 124 patients who underwent the surgery for RSCC at our institution. Propensity score matching (PSM) was performed to reduce the confounding effects to imbalances in the use of IUS. The IUS identified the main feeding artery and the accompanying vein in all 26 cases. After PSM, the amount of intraoperative blood loss in the IUS group was significantly lower than that in the conventional group (5 ml vs. 30 ml, p = 0.035) and no significant difference of the postoperative complications was observed. The IUS reduced the risk of bleeding in the surgery for RSCC. The IUS is a safe and feasible technique that help the surgeons for anatomical understandings under real-time condition in the laparoscopic surgery of RSCC.

Visualization of hydrocarbon chain length and degree of saturation of fatty acids in mouse livers by combining near-infrared hyperspectral imaging and machine learning

Fatty acids play various physiological roles owing to their diverse structural characteristics, such as hydrocarbon chain length (HCL) and degree of saturation (DS). Although the distribution of fatty acids in biological tissues is associated with lipid metabolism, in situ imaging tools are still lacking for HCL and DS. Here, we introduce a framework of near-infrared (1000-1400 nm) hyperspectral label-free imaging with machine learning analysis of the fatty acid HCL and DS distribution in the liver at each pixel, in addition to the previously reported total lipid content. The training data of 16 typical fatty acids were obtained by gas chromatography from liver samples of mice fed with various diets. A two-dimensional mapping of these two parameters was successfully performed. Furthermore, the HCL/DS plot exhibited characteristic clustering among the different diet groups. Visualization of fatty acid distribution would provide insights for revealing the pathophysiological conditions of liver diseases and metabolism.

Artificial intelligence for identification of focal lesions in intraoperative liver ultrasonography

PURPOSE

Intraoperative ultrasonography (IOUS) of the liver is a crucial adjunct in every liver resection and may significantly impact intraoperative surgical decisions. However, IOUS is highly operator dependent and has a steep learning curve. We describe the design and assessment of an artificial intelligence (AI) system to identify focal liver lesions in IOUS.

METHODS

IOUS images were collected during liver resections performed between November 2020 and November 2021. The images were labeled by radiologists and surgeons as normal liver tissue versus images that contain liver lesions. A convolutional neural network (CNN) was trained and tested to classify images based on the labeling. Algorithm performance was tested in terms of area under the curves (AUCs), accuracy, sensitivity, specificity, F1 score, positive predictive value, and negative predictive value.

RESULTS

Overall, the dataset included 5043 IOUS images from 16 patients. Of these, 2576 were labeled as normal liver tissue and 2467 as containing focal liver lesions. Training and testing image sets were taken from different patients. Network performance area under the curve (AUC) was 80.2 ± 2.9%, and the overall classification accuracy was 74.6% ± 3.1%. For maximal sensitivity of 99%, the classification specificity is 36.4 ± 9.4%.

CONCLUSIONS

This study provides for the first time a proof of concept for the use of AI in IOUS and show that high accuracy can be achieved. Further studies using high volume data are warranted to increase accuracy and differentiate between lesion types.

The utility of laparoscopic ultrasound during minimally invasive liver procedures in patients with malignant liver tumors who have undergone preoperative magnetic resonance imaging

BACKGROUND

The aim of this study was to assess the utility of laparoscopic ultrasound (LUS) during minimally invasive liver procedures in patients with malignant liver tumors who underwent preoperative magnetic resonance imaging (MRI).

METHODS

Medical records of patients with malignant liver lesions who underwent laparoscopic liver surgery between October 2005 and January 2018 and who underwent an MRI examination at our institution within a month before surgery were collected from a prospectively maintained database. The size and location of tumors detected on LUS, as well as whether they were seen on preoperative imaging, were recorded. Univariate and multivariate regression analyses were performed to identify factors that were associated with the detection of liver lesions on LUS that were not seen on preoperative MRI.

RESULTS

A total of 467 lesions were identified in 147 patients. Tumor types included colorectal cancer metastasis (n = 53), hepatocellular cancer (n = 38), neuroendocrine metastasis (n = 23), and others (n = 33). Procedures included ablation (67%), resection (23%), combined resection and ablation (6%), and diagnostic laparoscopy with biopsy (4%). LUS identified 39 additional lesions (8.4%) that were not seen on preoperative MRI in 14 patients (10%). These were colorectal cancer (n = 20, 51%), neuroendocrine (n = 11, 28%) and other metastases (n = 8, 21%). These additional findings on LUS changed the treatment plan in 13 patients (8.8%). Factors predicting tumor detection on LUS but not on MRI included obesity (p = 0.02), previous exposure to chemotherapy (p < 0.001), and lesion size < 1 cm (p < 0.001).

CONCLUSION

This study demonstrates that, despite advances in MRI, LUS performed during minimally invasive liver procedures may detect additional tumors in 10% of patients with liver malignancies, with the highest yield seen in obese patients with previous exposure to chemotherapy. These results support the routine use of LUS by hepatic surgeons.

The use of ultrasound in central vascular ligation during laparoscopic right-sided colon cancer surgery: technical notes

BACKGROUND

Complete mesocolic excision (CME) with central vascular ligation (CVL) requires the surgeon to sharply dissect the mesocolon and approach the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) for ligation of the supplying vessels relating to right-sided colon cancer at their origin. Even with preoperative images, it can still be challenging to identify these structures during laparoscopic surgery because of various intraoperative conditions. The aim of this study was to assess the efficacy of intraoperative ultrasound (IOUS) for identification of blood vessels during right-sided colon cancer surgery.

METHODS

We performed IOUS on 19 patients diagnosed with right-sided colon cancer at our institution, in January-October 2020. Preoperatively, a three-dimensional computed tomography (3D-CT) angiogram was obtained for the majority of patients to visualize the SMA, SMV, and their respective branches. The running position of the ileocolic artery (ICA) and right colic artery (RCA) related to the SMV and the presence of the middle colic artery were identified and compared using preoperative 3D-CT, IOUS, and intraoperative findings.

RESULTS

Nineteen patients [seven men and 12 women with a mean age of 73.9 ± 8.4 years (range 58-82 years)] were studied, including some with a body mass index of > 30 kg/m², locally advanced cancer, and severe adhesion. There were IOUSs that detected the SMA, SMV, and their tributaries in all patients. The positional relationships between the SMV and the ICA and RCA revealed by IOUS were consistent with the preoperative and intraoperative findings.

CONCLUSION

IOUS is a safe, feasible, and reproducible technique that can assist in detecting the branching of the SMA and SMV during CME with CVL in laparoscopic right-sided colon cancer surgery, regardless of individual conditions.

Routine Intraoperative Ultrasound for the Detection of Liver Metastases during Resection of Primary Colorectal Cancer - A Systematic Review

During the discovery of ColoRectal Cancer (CRC), 20% to 30% of patients have synchronous liver metastases. Ten to 30% of patients have non-evidence of Liver Metasteses (LM) following preoperative imaging such as Contrast-Enhanced Ultrasound (CE-US), multi-slice Contrast-Enhanced Computed Tomography (CE-CT), Contrast-Enhanced Magnetic Resonance Imaging (CE-MRI), and Positron Emission Tomography-Computed Tomography (PET-CT). Today, IntraOperative UltraSound (IOUS) in open surgery and Laparoscopic UltraSound (LUS) in laparoscopic or robotic surgery are considered the "gold standard" for detecting liver metastases. The object of this review is to demonstrate the higher sensitivity and specificity of IOUS and LUS in the detection rate of liver metastases.

Intraoperative ultrasound visualization of paravertebral anatomy in the retroperitoneal space during lateral lumbar spine surgery

OBJECTIVE

Lumbar surgery via a lateral approach is a minimally invasive and highly useful procedure. However, care must be taken to avoid its potentially fatal complications of intestinal and vascular injuries. The object of this study was to evaluate the usefulness of intraoperative ultrasound in improving the safety of lateral lumbar spine surgery.

METHODS

A transvaginal ultrasound probe was inserted into the operative field, and the intestinal tract, kidney, psoas muscle, and vertebral body were identified using B-mode ultrasound. The aorta, vena cava, common iliac vessels, and lumbar arteries and their associated branches were identified using the color Doppler mode.

RESULTS

The study cohort comprised 100 patients who underwent lateral lumbar spine surgery, 92 via a left-sided approach. The intestinal tract and kidney lateral to the psoas muscle on the anatomical approach pathway were visualized in 36 and 26 patients, respectively. A detachment maneuver displaced the intestinal tract and kidneys in an anteroinferior direction, enabling confirmation of the absence of organ tissues above the psoas. In all patients, the major vessels anterior to the vertebral bodies and the lumbar arteries and associated branches in the psoas on the approach path were clearly visualized in the Doppler mode, and their orientation, location, and positional relationship with regard to the vertebral bodies, intervertebral discs, and psoas were determined.

CONCLUSIONS

When approaching the lateral side of the lumbar spine in the retroperitoneal space, intraoperative ultrasound allows real-time identification of the blood vessels surrounding the lumbar spine, intestinal tract, and kidney in the approach path and improves the safety of surgery without increasing invasiveness.

Application of ultrasonography to high-tie and low-tie vascular ligation of the inferior mesenteric artery in laparoscopic colorectal cancer surgery: technical notes

BACKGROUND

Two ligation techniques can be applied in laparoscopy for left-sided colorectal cancer: (1) high-tie (HT), transection at the level of the inferior mesenteric artery (IMA); and (2) low-tie (LT), transection below the IMA, at the level of superior rectal artery (SRA), preserving the left colic artery (LCA). However, even with preoperative images, it can still be a challenge to identify these structures due to intraoperative individual conditions. In this study, we assess the use intraoperative ultrasonography (IOUS) to aid us in identifying the IMA and its branches to the SRA, LCA, and sigmoid artery.

METHODS

We performed IOUS in 18 patients diagnosed with left-sided colorectal cancer. Preoperatively, a three-dimensional computed tomography (3D-CT) angiography was obtained in majority of the patients, to visualize the IMA and its branches. Two patients were contraindicated to receive a contrast study, hence, was unable to undergo 3D-CT angiography. The resected specimen was grossly examined for the study. The bifurcation types were identified and compared using different modalities: preoperative 3D-CT, IOUS, and gross examination of the resected specimen.

RESULTS

The branching of the IMA revealed by IOUS was consistent to the findings preoperatively by the 3D-CT and postoperatively by the resected specimen. The IOUS result of the two patients without preoperative 3D-CT evaluation was also consistent with the post-operative bifurcation type.

CONCLUSIONS

IOUS is an easy and feasible modality which aids in detecting the branching of the IMA during LT and HT ligation in laparoscopic left-sided colorectal surgery. It can serve as an adjunct modality for 3D-CT angiography and can also be considered a safe alternative option for cases wherein 3D-CT angiography is unavailable.

Current status of surgical treatment of colorectal liver metastases

Liver metastasis (LM) is one of the major causes of death in patients with colorectal cancer (CRC). Approximately 60% of CRC patients develop LM during the course of their illness. About 85% of these patients have unresectable disease at the time of presentation. Surgical resection is currently the only curative treatment for patients with colorectal LM (CRLM). In recent years, with the help of modern multimodality therapy including systemic chemotherapy, radiation therapy, and surgery, the outcomes of CRLM treatment have significantly improved. This article summarizes the current status of surgical treatment of CRLM including evaluation of resectability, treatment for resectable LM, conversion therapy and liver transplantation for unresectable cases, liver resection for recurrent CRLM and elderly patients, and surgery for concomitant hepatic and extra-hepatic metastatic disease (EHMD). We believe that with the help of modern multimodality therapy, an aggressive oncosurgical approach should be implemented as it has the possibility of achieving a cure, even when EHMD is present in patients with CRLM.

Adjuvant Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) in resected high-risk colon cancer patients - study protocol for the PIPAC-OPC3 Trial. A prospective, controlled phase 2 Study

BACKGROUND

Peritoneal metastasis (PM) is the second most common site of recurrence in colon cancer (CC) patients and accounts for approximately one-third of all recurrences. Patients with T4 or intraperitoneal perforated colon cancers have an increased risk of developing PM, and since manifest PM is difficult to treat, high-risk patients should be offered prophylactic treatment. Here, we propose a study of adjuvant oxaliplatin administered as pressurized intraperitoneal aerosol chemotherapy (PIPAC OX) in patients with high-risk colon cancer (T4, perforated tumors, ovarian metastasis).

METHODS

PIPAC-OPC3 CC is a non-randomized, non-blinded phase 2 cohort study designed to treat high-risk colon cancer patients with adjuvant PIPAC-directed therapy. Based on an expected 90 % peritoneal recurrence-free survival with adjuvant PIPAC against the estimated 75 % without, 60 patients are needed (α: 0.05, power: 0.8). Eligible patients will receive two PIPAC treatments with oxaliplatin (92 mg/m2) at 4-6 week intervals. During laparoscopy, the peritoneum is biopsied at two locations, and peritoneal lavage with 500 mL of saline and laparoscopic ultrasound is performed. The patients are screened for adverse medical events and surgery-related complications after each PIPAC procedure. After the second PIPAC procedure, the patients will be examined in the outpatient clinic and followed with CT scans 12, 24 and 36 months after resection. The primary outcome of the PIPAC-OPC3 CC trial is to evaluate if PIPAC-directed adjuvant therapy can reduce the risk of PM. Secondary outcomes include the number of conversions from positive to negative peritoneal lavage cytology after one PIPAC procedure, completion rate of two adjuvant PIPAC treatments, toxicity and complication rate and recurrence-free and overall survival rates after 1, 3 and 5 years.

RESULTS

It is expected that PIPAC-directed adjuvant therapy can provide an absolute risk reduction of 15 % regarding the development of PM in high-risk colon cancer patients, and that this may result in increased survival rates. We expect that free intraperitoneal tumor cells (FITC) may be detected by peritoneal lavage performed just prior to the administration of PIPAC-directed therapy, and that this treatment may convert FITC-positive patients to a FITC-negative status.

CONCLUSIONS

This study may provide important knowledge to be used in designing additional studies on PIPAC in the adjuvant setting of other primary cancers.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT03280511 (2017-09-12). European Clinical Trials Database (EudraCT) 2017-002637-37.

Review of the literature laparoscopic surgery for metastatic hepatic leiomyosarcoma associated with smooth muscle tumor of uncertain malignant potential: Case report

Metastatic hepatic leiomyosarcoma is a rare malignant smooth muscle tumor. We report a case of metastatic hepatic leiomyosarcoma associated with smooth muscle tumor of uncertain malignant potential (STUMP). A 68-year-old female presented with a liver mass (60 mm × 40 mm, Segment 4). She underwent left salpingo-oophorectomy for an ovary tumor with STUMP in a broad ligament 6 years ago. Though FDG-PET showed obvious metabolically active foci, abnormal metabolically active foci other than the lesion were not detected. A malignant liver tumor was strongly suspected and laparoscopic partial liver resection was performed with vessel-sealing devices using the crush clamping method and Pringle maneuver. Immunohistochemical findings revealed metastatic liver leiomyosarcoma associated with STUMP in a broad ligament. This case is an extremely rare case of malignant transformation from primary STUMP to metastatic hepatic leiomyosarcoma. It provides important evidence regarding the treatment for metastatic hepatic leiomyosarcoma associated with STUMP.