Intraoperative Scanning Research Articles

From four-parathyroid gland exploration to a minimally invasive technique. Minimally invasive parathyroidectomy as a current approach in surgery for primary hyperparathyroidism.

Complete surgical resection of hyperfunctioning parathyriod tissue is essential for the treatment of primary hyperparathyroidism. During recent years, minimally invasive surgery has been successfully applied in neck exploration, because of significant developments of guidance by intraoperative scans, the use of quick, intraoperative PTH assay, and also preoperative imaging procedures such as high resolution ultrasonography and sestamibi scintigraphy. The results of operations which are performed with minimally invasive techniques are comparable to those of conventional surgery, and provide advantages with regard to cosmetic result, length of hospitalisation, and reduced post-operative pain.

50. Subcortical mapping and intraoperative DTT 3.0T of the corticospinal tract in supratentorial intrinsic tumor surgery. What should we rely on?

Introduction The course of the corticospinal tract (CST) can be identified using subcortical mapping (sc-MEP). The threshold technique (MEP-trsh) is considered to be reliable in setting the safe zone. Intraoperative DTT and sc-MEP correlation is thought to be more precise because of brainshift elimination. Goal of the study Evaluate intraoperative DTT 3.0T reliability comparing to CST mapping in nonselected patient series. Methods 25 patients were enrolled consecutively and prospectively from 7/2010 to 7/2012. Inclusion criteria: solitary supratentorial intracerebral lesion compressing or infiltrating the CST. Sc-MEP was performed by monopolar (cathodal) stimulation (500 Hz, 400 μ s, 5 pulses) with navigated probe. CST DTT was made both at preoperative and intraoperative 3.0T MRI. MEP-trsh current and probe-CST distance were recorded at 155 points before iMRI (preoperative scans), and at 103 points after iMRI (intraoperative scans). Current-distance correlations were performed both for pre-iMRI and for post-iMRI data separately. Results The correlation coefficient pre-iMRI was R = 0.470 (p 0.001), post-iMRI was R = 0.338 (p 0.001). MRI radical resection was achieved in 17 (68%), subtotal in 5 (24%) and partial in 3 (12%). Postoperative paresis developed in 8 (32%), permanent remained in one case (4%). Intraoperative DTT was unreliable because of image distortion in 9 (36%). Conclusion The linear current-distance correlation was found both in pre-iMRI and in post-iMRI data. Correlation of post-iMRI data was weaker. Intraoperative DTT was unreliable in 36%. Sc-MEPs remains superior, because of direct mapping of neural fibers and lack of technical failure. Supported by IGA MZ CR 12253–5.

2. Subcortical mapping and intraoperative DTT 3.0 T of the corticospinal tract in supratentorial intrinsic tumour surgery. What should we rely on?

Intraoperative subcortical mapping of the corticospinal tract (CST) using the threshold technique (sc-MEPs) is considered to be helpful during tumour resection adjacent to the CST. Diffusion tensor tractography (DTT) of the CST is feasible. Intraoperative DTT and sc-MEP correlation is thought to be more precise because of brainshift elimination. The goal of the study was to evaluate intraoperative DTT 3.0 T reliability compared with CST mapping in a nonselected series. 25 patients were enrolled consecutively and prospectively between June 2010 and June 2012. Inclusion criteria: solitary supratentorial intracerebral lesion compressing or infiltrating the CST according to preoperative MRI. Subcortical CST mapping was performed by monopolar (cathodal) stimulation (500 Hz, 400Î1/4s, 5 pulses) with a navigated probe. CST DTT was performedon both preoperative and intraoperative 3.0 T MRI. sc-MEP threshold current and probe-CST distance were recorded at 155 points before iMRI (intraoperative MRI) (preoperative scans) and at 103 points after iMRI (intraoperative scans). Current-distance correlations were performed both for pre-iMRI and for post-iMRI data separately. The correlation coefficient between pre-iMRI data was R = 0.470 (p < 0.001), post-iMRI data was R = 0.338 (p < 0.001). MRI radical resection was achieved in 17 (68%), subtotal in 5 (24%) and partial in 3 (12%). Postoperative paresis developed in 8 (32%), but was permanent in only one case (4%). The lowest sc-MEP threshold was ⩽ 5.0 mA in 10 (40%); 5–10.0 mA in 9 (36%); > 10.0 mA in 6 patients (24%). Intraoperative DTT became unreliable because of severe image distortion in 9 (36%). The linear current-distance correlation was found both in pre-iMRI and in post-iMRI data. Correlation of post-iMRI data was weaker. Neurophysiological subcortical mapping was more reliable intraoperatively than DTT. Combining these two methods can help increase the safety of tumour resection close to the CST only in selected cases. Supported by IGAMZCR12253-5.

Patient-Specific Minimum-Dose Imaging Protocols for Statistical Image Reconstruction in C-arm Cone-Beam CT Using Correlated Noise Injection.

A new method for accurately portraying the impact of low-dose imaging techniques in C-arm cone-beam CT (CBCT) is presented and validated, allowing identification of minimum-dose protocols suitable to a given imaging task on a patient-specific basis in scenarios that require repeat intraoperative scans. To accurately simulate lower-dose techniques and account for object-dependent noise levels (x-ray quantum noise and detector electronics noise) and correlations (detector blur), noise of the proper magnitude and correlation was injected into the projections from an initial CBCT acquired at the beginning of a procedure. The resulting noisy projections were then reconstructed to yield low-dose preview (LDP) images that accurately depict the image quality at any level of reduced dose in both filtered backprojection and statistical image reconstruction. Validation studies were conducted on a mobile C-arm, with the noise injection method applied to images of an anthropomorphic head phantom and cadaveric torso across a range of lower-dose techniques. Comparison of preview and real CBCT images across a full range of techniques demonstrated accurate noise magnitude (within ~5%) and correlation (matching noise-power spectrum, NPS). Other image quality characteristics (e.g., spatial resolution, contrast, and artifacts associated with beam hardening and scatter) were also realistically presented at all levels of dose and across reconstruction methods, including statistical reconstruction. Generating low-dose preview images for a broad range of protocols gives a useful method to select minimum-dose techniques that accounts for complex factors of imaging task, patient-specific anatomy, and observer preference. The ability to accurately simulate the influence of low-dose acquisition in statistical reconstruction provides an especially valuable means of identifying low-dose limits in a manner that does not rely on a model for the nonlinear reconstruction process or a model of observer performance.

Intraoperative Magnetic Resonance Imaging for Resection of Intra-Axial Brain Lesions: A Decade of Experience Using Low-Field Magnetic Resonance Imaging, Polestar N-10, 20, 30 Systems

The aim of this study was to determine the utility of an intraoperative magnetic resonance imaging (i-MRI) system (Polestar N-10, 20, 30) in achieving maximal resection of intra-axial brain lesions. The subjects comprised 163 patients with intra-axial brain lesions who underwent resection at Sheba Medical Center using the Polestar from February 2000 through February 2012. Demographic and imaging data were obtained and analyzed retrospectively. The patients included 83 men (50.9%) and had a mean age of 43 years. High-grade gliomas were diagnosed in 72 patients, low-grade gliomas in 35, metastases in 22, and various pathologies (e.g., cavernous angiomas, juvenile pilocytic astrocytoma, pleomorphic xanthoastrocytoma, etc.) were diagnosed in 34. The majority of the lesions (84, 51.5%) were located in or near eloquent areas. Fifty-one patients had nonenhancing lesions. We intended to achieve complete resection in 110 of 163 cases, based on preoperative imaging. Complete resection was achieved in 90 of these 110 (81.8%) cases. Intraoperative MRI led to additional resection in 42.3% of the total cases and to complete resection in 43.3% of all the cases in which a complete resection was achieved. In 76.8% of these cases, 2 intraoperative scans were sufficient to achieve complete resection. Sex, age, intent of resection, recurrence, affected side, and radiologic characteristics did not differ significantly between cases in which intraoperative MRI led to further resection and cases in which it did not. Nonenhancing lesions of all types were 3 times more likely to require additional resection after obtaining intraoperative MRIs (P = .02). The Polestar (N-10, 20, 30) proved useful for evaluating residual intra-axial brain lesions and achieving the maximal extent of resection in 42.3% of the total cases and in 43.3% of cases in which complete resection was achieved. Intraoperative MRI led to extended resection in 46.9% of patients for whom the initial intent was to perform an incomplete resection. Nonenhancement was the only independent variable predicting the usefulness of intraoperative MRI for additional lesion resection.

Routine spinal navigation for thoraco–lumbar pedicle screw insertion using the O-arm three-dimensional imaging system improves placement accuracy

Modern image-guided spinal navigation employs high-quality intra-operative three dimensional (3D) images to improve the accuracy of spinal surgery. This study aimed to assess the accuracy of thoraco-lumbar pedicle screw insertion using the O-arm (Breakaway Imaging, LLC, Littleton, MA, USA) 3D imaging system. Ninety-two patients underwent insertion of thoraco–lumbar pedicle screws guided by O-arm navigation over a 27month period. Intra-operative scans were retrospectively reviewed for pedicle breach. The operative time of patients where O-arm navigation was used was compared to a matched control group where fluoroscopy was used. A total of 467 pedicle screws were inserted. Four hundred and forty-five screws (95.3%) were placed within the pedicle without any breach (Gertzbein classification grade 0). Sixteen screws (3.4%) had a pedicle breach of less than 2mm (Gertzbein classification grade 1), and six screws (1.3%) had a pedicle breach between 2mm and 4mm (Gertzbein classification grade 2). The grade 2 screws were revised intra-operatively. There was no incidence of neurovascular injury in this series of patients. The mean operative time for O-arm patients was 5.25hours. In a matched control group of fluoroscopy patients, the mean operative time was 4.75hours. The difference in the mean operative time between the two groups was not statistically significant (p=0.15, paired t-test). Stereotactic navigation based on intra-operative O-arm 3D imaging resulted in high accuracy in thoraco–lumbar pedicle screw insertion.

A Fast CT and CT-Fluoroscopy Registration Algorithm With Respiratory Motion Compensation for Image-Guided Lung Intervention

CT-fluoroscopy (CTF) is an efficient imaging technique for guiding percutaneous lung intervention such as biopsy and ablation. In CTF-guided procedures, four to ten axial images are captured in a very short time period during breath holding to provide near real-time feedback of patients' anatomy so that physicians can adjust the needle as it is advanced toward a target lesion. Although popularly used in clinics, this procedure requires frequent scans to guide the needle, which may cause increased procedure time, complication rates, and radiation exposure to both clinicians and patients. In addition, CTF only generates a limited number of 2-D axial images and does not provide sufficient 3-D anatomical information. Therefore, how to provide volumetric anatomical information using CTF while reducing intraoperative scan is an important and challenging problem. In this paper, we propose a fast CT-CTF deformable registration algorithm that warps the inhale preprocedural CT onto the intraprocedural CTF for guidance in 3-D. In the algorithm, the deformation in the transverse plane is modeled using 2-D B-Spline, and the deformation along z-direction is regularized by smoothness constraint. A respiratory motion compensation framework is also incorporated for accurate registration. A parallel implementation strategy is adopted to accomplish the registration in several seconds. With electromagnetic tracking, the needle position can be superimposed onto the deformed inhale CT image, thereby providing 3-D image guidance during breath holding. Experiments were conducted using both simulated CTF images with known deformation and real CTF images captured during lung cancer biopsy studies. The experiments demonstrated satisfactory registration results of our proposed fast CT-CTF registration algorithm.

Intraoperative Visualization of Residual Tumor

High-field, intraoperative magnetic resonance imaging (iMRI) achieves free tumor margins in glioma surgery by involving anatomic neuronavigation and sophisticated functional imaging. To evaluate the role of perfusion-weighted iMRI as an aid to detect residual tumor and to guide its resection. Twenty-two patients undergoing intraoperative scanning (in a dual-room 1.5-T magnet setting) during the resection of high-grade gliomas were examined with perfusion-weighted iMRI. The generated relative cerebral blood volume (rCBV) maps were scrutinized for any hot spots indicative of tumor remnants, and region-of-interest analysis was performed. Differences among the rCBV region-of-interest estimates in residual tumor, free tumor margins, and normal white matter were analyzed. Histopathology of the tissue specimens and the neurosurgeon's intraoperative macroscopic estimations were considered the reference standards. In all cases, diagnostic rCBV perfusion maps were generated. Interpretation of perfusion maps demonstrated that gross total resection of gliomas was achieved in 4 of 22 cases (18%), which was macroscopically and histopathologically verified, whereas in 18 of 22 cases (82%), the perfusion-weighted iMRI revealed hot spots indicating subtotal tumor removal. The latter proved to be true in all but 1 case. The receiver-operating characteristic curves of the qualitative visual and quantitative analyses showed excellent sensitivity and specificity rates. Statistical analysis demonstrated statistically significant differences for the mean rCBV and maximum rCBV between residual disease and tumor-free margins (P = .002 for both). Perfusion-weighted iMRI may be implemented easily into imaging protocols and may assist the surgeon in detecting residual tumor volume.

Estimating the Effective Radiation Dose Imparted to Patients by Intraoperative Cone-Beam Computed Tomography in Thoracolumbar Spinal Surgery

Observational. To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios. Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses. Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors. Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3. We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.

Intraoperative computed tomography guidance to confirm decompression following endoscopic endonasal approach for cervicomedullary compression.

Introduction Cervicomedullary compression often requires an anterior approach to address the compressive vector. In certain cases an endoscopic endonasal approach (EEA) is ideal for decompression. It is essential that an adequate decompression be achieved and verified before the patient leaves the operating room. The purpose of this study was to evaluate the use intraoperative computed tomography (IO-CT) in assessing the adequacy of decompression. Methods A retrospective chart review revealed 11 cases of EEA odontoid resection IO-CT verification of decompression. Operative reports and review of imaging was used to determine if further decompression was performed following the intraoperative scan. Results Out of 11 EEA cases, 4 (36%) patients showed evidence of residual compression following an initial IO-CT. Further operative decompression was undertaken following the first scan in all cases. A second intraoperative scan was then used to confirm complete decompression. No patient left the operating room with residual compression. Discussion IO-CT provided valuable utility in 36% of the cases after the initial resection was incomplete. The standard fluoroscopic guidance may not provide adequate resolution and enhanced utility like IO-CT.

Intraoperative SD-OCT in Macular Surgery

Intraoperative use of spectral-domain optical coherence tomography (SD-OCT) using an OCT-mounted surgical microscope could provide additional information to predict visual outcomes of macular surgery and identify intraoperative changes in the macular anatomy that affect visual recovery. This interventional retrospective case study included 5 eyes of 5 consecutive patients with various macular pathologies. All patients underwent the standard surgery for idiopathic macular holes and epiretinal membranes (ERMs) using the same 25-gauge three-port pars plana technique. If present, the ERM was removed. The dye procedure was then repeated to stain and remove the internal limiting membrane (ILM). OCT images were obtained with the retinal map or cross-section program preincision, post-hyaloid elevation (if applicable), post-residual ERM peel (if applicable), and post-ILM peel. In 3 of 5 patients, the intraoperative scan revealed an increased area of subretinal hyporeflectivity corresponding with a clinically visible "cuff" of retinal detachment. In 2 patients, the SD-OCT scan taken immediately after ERM removal helped find a cleavage plane for the subsequent ILM peeling, which could be further confirmed by a scan taken immediately after it. In 2 cases, the scans identified intraoperative complications that otherwise would not have been noted and allowed the surgeon to modify the next procedures during surgery. Use of this technology in an operative setting can provide greater insight into the changes in retinal anatomy created during macular surgery.

The accuracy of 3D image navigation with a cutaneously fixed dynamic reference frame in minimally invasive transforaminal lumbar interbody fusion

Objective: In contrast to preoperative image-based 3D navigation systems, which require surgeon-dependent registration, an intraoperative cone-beam computed tomography (cb-CT) image-based 3D navigation system allows automatic registration during the acquisition of 3D images intraoperatively. Thus, the need for spinal exposure for point matching is obviated, making a cb-CT image-based navigation system ideal for use in minimally invasive spinal procedures. Conventionally, the dynamic reference frame (DRF) is mounted to an adjacent spinous process or iliac bone through a separate incision. However, the close proximity of the DRF to the surgical area may result in its interfering with the surgical procedure or causing streak artifacts on the navigation images. Cutaneous placement of the DRF overlying the sacral hiatus is one possible solution to these problems, but such a placement does not provide a solid bony fixation point and is distant from the surgical area, both of which factors may hinder the accuracy of the navigation. The purpose of this study was to evaluate the accuracy of a novel idea for DRF placement in a series of mini-open transforaminal lumbar interbody fusion (TLIF) procedures performed with intraoperative cb-CT image-based 3D navigation.Methods: From June 2009 to December 2009, 20 patients underwent mini-open TLIF for a total 82 pedicle screws placed in the lumbar spine with cutaneous placement of the DRF overlying the sacral hiatus. The pedicle screws were inserted under navigational guidance using cb-CT data acquired intraoperatively with a Medtronic O-arm. Screw positions were subsequently checked with a final intraoperative cb-CT scan. Nineteen patients underwent single-level fusion (8 at L4–5, 6 at L5–S1, 4 at L3–4, and 1 at L2–3) and one patient underwent two-level fusion (from L3–5).Results: There were 4 (4.9%) pedicle perforations greater than 2 mm out of the 82 pedicle screw insertions in the 20 patients. Two of these breached screws were repositioned and confirmed to be in place with a final intraoperative cb-CT. There were no complications of neural injury associated with these perforations.Conclusion: A cutaneously mounted DRF overlying the sacral hiatus provides accuracy in intraoperative 3D image guided navigation for mini-open TLIF that is comparable to that obtained in other reported series using a fixed bony attachment point for the DRF.

Sentinella: Portable gamma camera versus conventional scintigram for intraoperative sentinel lymph node detection in breast cancer.

22 Background: Sentinel lymph node biopsy (SLNB) is a standard practice for staging the axilla in breast cancer. Access to nuclear medicine department and sentinel node imaging remain an issue in number of hospitals in the UK and rest of the world. Preoperative scintigrams are performed to confirm uptake of radioactivity and localisation of nodes in centres where facilities are available. Sentinella is a portable imaging camera used intraoperatively to produce real time visual localisation of SLNs. Sentinella was tested in a controlled laboratory environment at our centre followed by the first use of this device in breast cancer patients from UK. Methods: Sensitivity and spatial resolution of Sentinella was compared with conventional gamma camera (CGC).Intraoperative Sentinella Scans were performed in 130 patients and their yield compared with Lymphoscintigrams from CGC. Further Sentinella scans were performed after the axilla was deemed clear by silent activity of hand held gamma probe. Results: Sentinella resolution is comparable with the CGC for objects close to the camera. Sentinella detects high radioactivity (500 kBq) faster than CGC (1 vs 2.5min). In cases of low radioactivity (10kBq) Sentinella was equally accurate and faster than CGC, when placed nearer to skin.Intra-operative Sentinella scans detected an average of 2 sentinel nodes compared to 1.4 nodes by CGC scans. Sentinella demonstrated a serial decay in activity with removal of every hot node and its LED guidance helped in detecting residual nodes. Sentinella picked up extra nodes in 5/130 cases after the axilla was found silent using hand held gamma probe. In 2/130 cases extra nodes found using Sentinella had presence of cancer that led to a complete axillary clearance. Conclusions: This data confirms the excellent sensitivity and specificity of the machine in localisation of radioactive nodes. This new imaging technique increases our pick up of SLNs intraoperatively that are missed due to inadequate visualisation and provide a superior detection compared to static scintigram imaging. This portable gamma camera can replace the use of conventional lymphoscintigrams saving camera time and cost.

Application of high-field intraoperative magnetic resonance imaging in stereotactic aspiration and drainage of hypertensive hematomas

To explore the application values of high-field intraoperative magnetic resonance imaging (MRI) in stereotactic aspiration and drainage of hypertensive hematomas. During a period of August 2011 to January 2012, 11 patients with hypertensive hemorrhage were examined preoperatively by conventional MRI and diffusion tensor imaging (DTI) with 1.5T intraoperative MRI system (Signa HDi, GE, USA) at Tianjin Medical University General Hospital. The anatomic relationship of corticospinal tract (CST) and hematoma was used for the operative planning with the neuronavigation planning workstation (iPlan Cranial 3.0 software, BrainLab, Germany) for 3D reconstruction. During stereotactic surgery, intraoperative MRI scan was performed. According to the clearance rate of hematomas, the operators decided to finish the operation or update the operative planning to continue hematoma removal. All patients were reexamined by conventional MRI and DTI at Week 3 postoperation. Then comparative analysis was performed for the preoperative and postoperative integrity of CST. No death or severe complications occurred. All patients showed improvement of motor function and the postoperative integrity of CST. The intracranial condition may be monitored effectively by intraoperative MRI throughout surgery so as to increase the rate of hematoma removal and reduce the postoperative complications.

Research on the application of intraoperative magnetic resonance in transnasal ⁃sphenoidal surgery for pituitary adenoma

Objective To discuss the application of the intraoperative magnetic resonance imaging (iMRI) ⁃ based neuronavigation system in transnasal ⁃ sphenoidal surgery for pituitary adenoma. Methods Thirty ⁃ eight pituitary adenomas were resected via nasal ⁃ sphenoidal approach with assistance of the American GE Signa 1.5T intraoperative magnetic resonance system associating German Brain LAB neuronavigation system. The clinical materials, iMRI quality and its influence on the surgical process and results were analyzed. Results Intraoperative scanning was performed 2 or 3 times in each patient, averaging (2.11 + 0.41) times. The scanning time was 3-5 min, and adding the packaging and transporting process, the whole procedure required 15-20 min. Posing the position, fixing the head rest and navigation registering took 32-40 min in all. So the total operation may last 47-60 min, averaging (51.20 + 0.66) min. The iMRI was used to scan and collect pictures. Residual tumor tissue was revealed in 11 cases. Eight of the 11 cases underwent total resection according to the new neuronavigation plan. The other 3 cases under⁃ went subtotal resection because the adenomas were tenacious and adhered closely to the surrounding significant structures. By using this iMRI system, the total resection rate (TRR) of adenoma increased from 71.05% (27/38) to 92.10% (35/38). It was raised by 21.05% (8/38; χ2 = 4.290, P = 0.018). There was no iMRI related complication occurred. Conclusion The application of iMRI ⁃ based neuronavigation technology in transnasal ⁃ sphenoidal operations for pituitary adenoma provides objective evidence for the guidance of surgical procedure and real time assessment of surgical results, which may lead to higher TRR and avoid deviation of navigation caused by brain⁃drift in transnasal⁃sphenoidal operation. DOI：10.3969/j.issn.1672⁃6731.2012.02.022

Optic radiation tractography and vision in anterior temporal lobe resection

ObjectiveAnterior temporal lobe resection (ATLR) is an effective treatment for refractory temporal lobe epilepsy but may result in a contralateral superior visual field deficit (VFD) that precludes driving in the seizure-free patient. Diffusion tensor imaging (DTI) tractography can delineate the optic radiation preoperatively and stratify risk. It would be advantageous to incorporate display of tracts into interventional magnetic resonance imaging (MRI) to guide surgery.MethodsWe studied 20 patients undergoing ATLR. Structural MRI scans, DTI, and visual fields were acquired before and 3 to 12 months following surgery. Tractography of the optic radiation was performed on preoperative images and propagated onto postoperative images. The anteroposterior extent of the damage to Meyer's loop was determined, and visual loss was quantified using Goldmann perimetry.ResultsTwelve patients (60%) suffered a VFD (10–92% of upper quadrant; median, 39%). Image registration took <3 minutes and predicted that Meyer's loop was 4.4 to 18.7mm anterior to the resection margin in these patients, but 0.0 to 17.6mm behind the resection margin in the 8 patients without VFD. The extent of damage to Meyer's loop significantly correlated with the degree of VFD and explained 65% of the variance in this measure.InterpretationThe optic radiation can be accurately delineated by tractography and propagated onto postoperative images. The technique is fast enough to propagate accurate preoperative tractography onto intraoperative scans acquired during neurosurgery, with the potential to reduce the risk of VFD. ANN NEUROL 2012;

Reconstruction of portal vein in liver surgery

As an essential technique involved in complicated liver surgery,portal vein reconstruction results in eradication of macro- or microscopic tumor residual on surgical margins when combined with precise hepatectomy,improving both the living quality and the survival rate of patients.The application of this reconstruction technique needs precise evaluation of pre-operational image data,clearly dissection of portal vessels and tremendous amount of collaborative effort by the surgery team. Other techniques performed during the surgical procedure include intra-operative ultrasound scan,revitalizing the cryopreserved vessels,and angioplasty. Key words: Portal vein reconstruction; Liver surgery; Hepatocellular carcinoma; Hilar carcinoma; Gallbladder carcinoma

The Accuracy of Intraoperative O-arm Images for the Assessment of Pedicle Screw Postion

Human cadaveric study. The objective of the study was to determine the accuracy of intraoperative O-arm images in determining pedicle screw position using open dissection as the gold standard. Pedicle screws are widely used in the treatment of various spinal disorders. Postoperative computed tomographic scans are the imaging gold standard to detect pedicle screw malposition. However, a second procedure is necessary if such malpositioned screws have to be revised. The O-arm is an intraoperative scanner that allows revision of a screw without having to return the patient to the operating room for a separate procedure. No previous studies have looked at the accuracy of intraoperative O-arm images in determining pedicle screw position. This factorial validation study utilized 9 cadavers in a comparison of intraoperative O-arm images and the dissection gold standard. Four hundred sixteen screws were inserted using 3-dimensional image (O-arm) guidance from C2 to S1. The screw positions were randomized into 3 groups: "IN" (fully contained within the pedicle), "OUT-lateral," or "OUT-medial." After screw insertion, O-arm images were obtained and reviewed in a blinded fashion by 3 independent observers. Dissection identified the true position of the screws. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using dissection results as the gold standard. The interobserver reliability was also determined. The overall accuracy, specificity, sensitivity, PPV, and NPV of O-arm images for the thoracic and lumbar spine were 73%, 76%, 71%, 74%, and 72%, respectively. Accuracy of surgeon perception in the cervical spine was significantly less than in the thoracic and lumbosacral spine. There was substantial interobserver agreement between the 3 readers. Intraoperative O-arm images accurately detect significant pedicle screw violations in the thoracic and lumbosacral spine but are less accurate for the cervical spine.

The significance of intraoperative computed tomograph scan for complex acetabular fractures

Objective To investigate the application of intraoperative Computed Tomograph (CT) using in surgery for complex acetabular fractures.Methods From June 2008 to December 2010,14 patients (9 males,5 females; with the mean age of 45.1 years; range,28-62 years) with complex acetabular fractures were operated using intraoperative CT.Preoperative radiotherapy and CT scan were adopted to evaluate the fractures.Three dimensional reconstruction based on CT scan was used to mimic surgery.The surgery approach and the type of internal fixators were noted.Intraoperative C-arm and CT scan were used to evaluate the fractures reduction respectively.Decision of additional reduction was made by surgeons according to above mentioned methods respectively and the results were noted.Comparing to preoperative design,the change of surgery plan were noted.Overall time,frequency and radiation dose of intraoperative CT scan were also noted.Results All patients in this study received average 2.7 times of intraoperative CT scan.Mean time of CT scan was 40.4 min and the overall dose of radiation was 47.2 mGy.Decision of additional reduction was made in 3 cases according to C-arm radiography and 4 cases according to CT scan (above mentioned 3 cases were included).The change of surgery plan was made in one case.In postoperative radiography evaluation according to Matta's score system,anatomical reduction were achieved in 8 cases,imperfect reduction in 3 cases and poor reduction in 3 cases.Conclusion Intraoperative CT scan increases the radiation time and dose of patients dramatically.When used to evaluate fracture reduction intraoperatively,it can't take the advantage of traditional C-arm radiography.When delicate preoperative plan is made with radiography and three dimensional reconstruction based on CT data,the efficiency of intraoperative CT scan for complex acetabular fractures are to be discussed. Key words: Acetabulum; Fractures, bone; Surgery, computer-assisted

Evaluation of the rate of decompression in anterior cervical corpectomy using an intra-operative computerized tomography scan (O-Arm system)

The purpose of this study was to evaluate the efficacy of intra-operative computerized tomography (CT) scanning in the analysis of bone removal accuracy during anterior cervical corpectomy, in order to allow any necessary immediate correction in the event of inadequate bone removal. From September 2009 to December 2010 we performed an intra-operative (CT) scan using the O-Arm(™) Image system to assess the rate of central and lateral decompression in all patients treated for cervical spondylotic myelopathy by anterior cervical corpectomy and fusion. Out of a population of 187 patients admitted to our department, with a diagnosis of myelopathy due to spondylotic degenerative cervical stenosis, 15 patients underwent a surgical treatment with anterior cervical corpectomy and fusion. There were nine males (60%) and six females (40%); the mean age was 52.4 years, ranging from 41 to 57 years. The pre-operative radiologic investigations (MRI and CT scans) revealed in the nine patients (60%) the extent of the compression to one vertebral body (C4 one case, C5 four cases, C6 four cases), while in the six cases (40%) the compression regarded two vertebral body (C3 and C4 one case, C4 and C5 two cases, C5 and C6 three cases). During surgery, when the decompression was judged completely, a CT scan was performed: in 11 cases (73.3%) the decompression was considered adequate, while in four cases (26.7%) it was deemed insufficient and the surgical strategy was changed in order to optimize the bone removal. In these cases an additional scan was taken to prove the efficacy of decompression, achieved in all patients. Intra-operative CT scan performed during cervical corpectomy is a really useful tool in helping to ensure complete bone removal and the adequacy of surgery. The O-arm(™) Image system grants optimal image quality, allowing correctly assessing the rate of decompression and, in any case of doubt, allows an intra-operative evaluation of the final correct positioning of the graft.