Intraoperative Ultrasonography Imaging Research Articles

Artificial intelligence for identification of focal lesions in intraoperative liver ultrasonography.

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. 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. 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%. 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.

Superficial Siderosis With Verrucous Vegetation Around a Dural Defect Confirmed by Intraoperative Ultrasonography

Superficial siderosis (SS) of the central nervous system (CNS) is a rare disease caused by repeated hemorrhages in the subarachnoid space. We describe surgical treatment of an SS case in which a dural defect with verrucous vegetation in the spinal canal was detected by intraoperative ultrasonography (US). After laminectomy, intraoperative US imaging confirmed verrucous vegetation and epidural fluid collection around the ventral dural defect before incision of the posterior dura mater. As intraoperative US also showed a dural defect at the ventral and right sides of the spinal cord, the posterior dural incision was made in a manner that was slightly more right lateral than standard midline. The ventral dural defect was repaired by direct sutures. After repair, intraoperative US imaging confirmed dural hole closure, removal of vegetation and resolution of the collected fluid. Dural closure was successful and symptoms partially improved despite the patient’s long history of SS. Intraoperative US can help surgeons make decisions about precise dural incision before repair. Intraoperative US is useful for detecting the level of dural defect and verrucous vegetation before repair and confirming closure of the dural defect, successful removal of vegetation and resolution of fluid collection after repair. J Med Cases. 2020;11(7):192-195 doi: https://doi.org/10.14740/jmc3495

Superficial Siderosis With Verrucous Vegetation Around a Dural Defect Confirmed by Intraoperative Ultrasonography

Superficial siderosis (SS) of the central nervous system (CNS) is a rare disease caused by repeated hemorrhages in the subarachnoid space. We describe surgical treatment of an SS case in which a dural defect with verrucous vegetation in the spinal canal was detected by intraoperative ultrasonography (US). After laminectomy, intraoperative US imaging confirmed verrucous vegetation and epidural fluid collection around the ventral dural defect before incision of the posterior dura mater. As intraoperative US also showed a dural defect at the ventral and right sides of the spinal cord, the posterior dural incision was made in a manner that was slightly more right lateral than standard midline. The ventral dural defect was repaired by direct sutures. After repair, intraoperative US imaging confirmed dural hole closure, removal of vegetation and resolution of the collected fluid. Dural closure was successful and symptoms partially improved despite the patient’s long history of SS. Intraoperative US can help surgeons make decisions about precise dural incision before repair. Intraoperative US is useful for detecting the level of dural defect and verrucous vegetation before repair and confirming closure of the dural defect, successful removal of vegetation and resolution of fluid collection after repair.

Using Real-Time Fusion Imaging Constructed from Contrast-Enhanced Ultrasonography and Magnetic Resonance Imaging for High-Grade Glioma in Neurosurgery

To compare the observation of high-grade glioma (HGG) based on intraoperative multiplane ultrasonography (US) images and preoperative reconstructive coplanar T1-weighted enhanced magnetic resonance imaging (MRI) using volume navigation (V Nav) fusion image technology. We retrospectively evaluated intraoperative data obtained from 16 patients diagnosed with HGG (grade III and IV). Overall, 18 nodules observed in 15 patients were examined. HGG images from US and contrast-enhanced US (CEUS) were compared with those from preoperative reconstructive coplanar enhanced T1-weighted MRI using automatic V Nav fusion image technology. All HGG tumors were detected. Images of 13 of 18 tumors (72.2%) with obscure margins using B-mode US were improved with clear tumor boundaries using CEUS imaging. The relative difference in tumor area between CEUS and enhanced MRI modalities in 14 mainly solid component lesions was considered statistically significant (P value < 0.05). There was a perfect correlation of the enhanced area between coplanar CEUS and enhanced MRI. The V Nav fusion image system combining intraoperative real-time US imaging with reconstructive preoperative coplanar MRI is valuable for image-guided HGG resection. It is suitable for neurosurgeons who lack the expertise in US technology to discern the brain structure and allows better recognition of tumor and edema tissues compared with reconstructive preoperative coplanar-enhanced MRI in real time and in multiplane from different angles. In addition, CEUS combined with B-mode US could improve tumor detection and resection control in neurosurgery, even in single US-guided operations.

Intraoperative mapping and monitoring of the corticospinal tracts with neurophysiological assessment and 3-dimensional ultrasonography-based navigation

Preserving motor function is a major challenge in surgery for intraaxial brain tumors. Navigation systems are unreliable in predicting the location of the corticospinal tracts (CSTs) because of brain shift and the inability of current intraoperative systems to produce reliable diffusion tensor imaging data. The authors describe their experience with elaborate neurophysiological assessment and tractography-based navigation, corrected in real time by 3D intraoperative ultrasonography (IOUS) to identify motor pathways during subcortical tumor resection. A retrospective analysis was conducted in 55 patients undergoing resection of tumors located within or in proximity to the CSTs at the authors' institution between November 2007 and June 2009. Corticospinal tract tractography was coregistered to surgical navigation-derived images in 42 patients. Direct cortical-stimulated motor evoked potentials (dcMEPs) and subcortical-stimulated MEPs (scrtMEPs) were recorded intraoperatively to assess function and estimate the distance from the CSTs. Intraoperative ultrasonography updated the navigation imaging and estimated resection proximity to the CSTs. Preoperative clinical motor function was compared with postoperative outcome at several time points and correlated with incidences of intraoperative dcMEP alarm and low scrtMEP values. The threshold level needed to elicit scrtMEPs was plotted against the distance to the CSTs based on diffusion tensor imaging tractography after brain shift compensation with 3D IOUS, generating a trend line that demonstrated a linear order between these variables, and a relationship of 0.97 mA for every 1 mm of brain tissue distance from the CSTs. Clinically, 39 (71%) of 55 patients had no postoperative deficits, and 9 of the remaining 16 improved to baseline function within 1 month. Seven patients had varying degrees of permanent motor deficits. Subcortical stimulation was applied in 45 of the procedures. The status of 32 patients did not deteriorate postoperatively (stable or improved motor status): 27 of them (84%) displayed minimum scrtMEP thresholds > 7 mA. Six patients who experienced postoperative deterioration quickly recovered (within 5 days) and displayed minimum scrtMEP thresholds > 6.8 mA. Five of the 7 patients who had late (> 5 days postoperatively) or no recovery had minimal scrtMEP thresholds < 3 mA. An scrtMEP threshold of 3 mA was found to be the cutoff point below which irreversible disruption of CST integrity may be anticipated (sensitivity 83%, specificity 95%). Combining elaborate neurophysiological assessment, tractography-based neuronavigation, and updated IOUS images provided accurate localization of the CSTs and enabled the safe resection of tumors approximating these tracts. This is the first attempt to evaluate the distance from the CSTs using the threshold of subcortical monopolar stimulation with real-time IOUS for the correction of brain shift. The linear correlation between the distance to the CSTs and the threshold of subcortical stimulation producing a motor response provides an intraoperative technique to better preserve motor function.

Real-Time Ultrasonography-Computed Tomography Fusion Imaging for Staging of Hepatic Metastatic Involvement in Patients With Colorectal Cancer

To prospectively evaluate the role of real-time ultrasonography (US)-computed tomography (CT) fusion imaging (US-CT) in comparison with US seeing separate CT images (US + CT) and multidetector-row CT (MDCT) for the correct staging of hepatic metastatic involvement in patients with colorectal cancer. Sixty-four patients with newly diagnosed colorectal cancer and who were referred for abdominopelvic staging before primary tumor resection underwent same-day MDCT, US + CT, and US-CT. Examinations were evaluated on-site by 2 investigators in consensus. Investigators recorded the size and location of detected lesions on segmental liver maps, classified them as being benign, malignant, or indeterminate, and finally assessed the M stage of the liver as being M0, M1, or Mx (indeterminate). All patients underwent surgical exploration including intraoperative US. Reference standard diagnosis was based on findings at surgery, intraoperative US, histopathology, and MDCT follow-up imaging. Differences among investigated modalities were analyzed using McNemar's test. The reference standard verified 109 (45 < or = 1 cm) hepatic lesions in 25 patients, including 65 (25 < or = 1 cm) metastases in 16 patients (M1). Regarding the 45 < or = 1 cm liver lesions, rates for detection were significantly higher (P < 0.05) for MDCT (80%, 36/45) and US-CT (77.8%, 35/45) than for US + CT (64.4%, 29/45); the rate for correct classification by US-CT (71.1%, 32/45) was significantly higher than for US + CT (48.9%, 22/45) and MDCT (31.1%, 14/45) (all P < 0.05). On patient-based analysis, specificity of MDCT (85.4%, 41/48) was significantly lower (P < 0.05) than for US-CT (97.9%, 47/48) and US + CT (93.7%, 45/48); the positive predictive value of MDCT (63.1%, 12/19) was not significantly different (P = 0.27) compared with US + CT (82.3%, 14/17) but significantly lower (P < 0.05) than for US-CT (93.7%, 15/16). In 13 patients (59 lesions) with only benign (stage M0) or coexistent benign and malignant lesions (stage M1), indeterminate lesion ratings and indeterminate liver stagings (Mx) occurred both significantly lower (P < 0.05) with US-CT (3.4%, 2/59; and 0%, 0/13) than with US + CT (11.9%, 7/59; and 23.1%, 3/13) or with MDCT (30.5%, 18/59; and 53.8%, 7/13). Based on these initial diagnostic experiences, complementary US-CT fusion imaging of small CT-indeterminate liver lesions may have value in staging patients with colorectal cancer, focusing on patients who were likely to harbor only benign or coexisting benign and malignant liver lesions and in whom change of M staging would change the clinical management.

Prediction of Clinical Results of Laminoplasty for Cervical Myelopathy Focusing on Spinal Cord Motion in Intraoperative Ultrasonography and Postoperative Magnetic Resonance Imaging

Retrospective analysis of preoperative imaging and clinical data from patients undergoing cervical expansive laminoplasty for cervical myelopathy. To investigate preoperative parameters that predict the floating status of the spinal cord at the anterior elements of the cervical spine in both intraoperative ultrasonography (US) and postoperative magnetic resonance imaging (MRI), and to evaluate the association between clinical outcome and spinal cord floating. Intraoperative US has been used to evaluate the status of the spinal cord after cervical laminoplasty for cervical myelopathy. Few studies have evaluated the predictive preoperative parameters for intraoperative US results. Imaging and clinical outcome data were collected from 101 consecutive patients who underwent cervical expansive laminoplasty for cervical myelopathy at Kaikoukai Nagoya Kyouritsu Hospital, Japan, from April 2004 to April 2008. The preoperative parameters associated with spinal cord floating in intraoperative US and postoperative MR images were investigated. Predictive parameters for the rate of recovery according to the Japanese Orthopedic Association score for cervical myelopathy at each follow-up session were also investigated. Predictive parameters for spinal cord floating after decompression in intraoperative US were the cervical vertebrae 2 to 7 (C2-C7) sagittal alignment in the standing neutral position on preoperative plain radiograph radiography (cut-off value=3 degrees) and the C5/6 "beak angle" in preoperative MRI (cut-off value=20 degrees). A predictive parameter for spinal cord floating in postoperative MRI was the C5/6 beak angle in preoperative MRI (cut-off value=21 degrees). The preoperative Japanese Orthopedic Association score and spinal cord floating at anterior elements of the cervical spine in intraoperative US were predictive parameters for clinical outcome. Intraoperative US was more useful than postoperative MRI for predicting the clinical outcome of cervical expansive laminoplasty. Knowledge of the predictive parameters for spinal cord floating after cervical expansive laminoplasty could help evaluate the limitations of posterior decompression.

Intraoperative US of the Liver: Techniques and Clinical Applications

Intraoperative ultrasonography (US) of the liver provides the operating surgeon with useful real-time diagnostic and staging information that may result in an alteration in the planned surgical approach. Current applications for intraoperative US of the liver include tumor staging, metastatic survey, guidance for metastasectomy and various tumor ablation procedures, documentation of vessel patency, evaluation of intrahepatic biliary disease, and guidance for whole-organ or split-liver transplantation. To obtain the most useful information with intraoperative US, the sonographer should use a dedicated transducer and a scanning method appropriate for the purpose of the examination. In addition, the radiologist must be familiar with the relevant intraoperative and vascular anatomy and the spectrum of normal and abnormal findings and should be alert to the pitfalls that frequently occur in the interpretation of intraoperative US images of the liver.

Sacroperineal anorectoplasty using intraoperative ultrasonography: A preliminary report

Intraoperative ultrasonography (US) was applied to sacroperineal anorectoplasty for the purpose of making a pull-through tunnel under visual guidance. Intraoperative US images the horizontal plane of the muscle complex and the tip of the forceps, which is placed at the entrance of the tunnel (ie, the space anterior to the puborectalis sling), ready to penetrate the muscle complex. A surgeon can thus penetrate the center of the muscle by confirming the relation between the muscle and forceps on the US screen. Postoperative computed tomography of four patients on whom this technique was applied demonstrated that the rectum was pulled through the exact center of the puborectalis and external sphincter muscles.