Image-guided Method Research Articles

CT-guidance interstitial Iodine-125 seed brachytherapy as a salvage therapy for recurrent head and neck carcinoma

Objective: To investigate the efficacy of CT-guidance interstitial Iodine-125 seed brachytherapy as a salvage therapy for recurrent head and neck carcinoma. Methods: A total of 122 patients who had been treated for recurrent head and neck carcinoma with CT-guided Iodine-125 seed permanent implantation were conducted a retrospective analysis at Peking University Third Hospital from February 2003 to December 2015. The study included 78 male and 44 female patients. Of the 122 patients, 76 had undergone radical surgery, 106 had received EBRT. Among the patients who underwent EBRT, the total dose delivered to PTV ranged from 30 to 140 Gy (median, 68.4 Gy). The actuarial median number of the implanted Iodine-125 seeds was 38 (range, 5-158). The specific activity of Iodine-125 seeds ranged from 14.8 to 28.9 MBq/seed (median, 22.2 MBq). The evaluation of post plan showed the actuarial D90 ranged from 46 to 282 Gy (median, 121 Gy). The overall local control and survival times were determined by using the Kaplan-Meier method from SPSS 13.0.Univariate analysis was performed on the local control rate and overall survival rate. Results: Tumor responses rate was 75.4%. The median local control time was 10.0 months (95% CI 9.8-24.2 months), and the 1-, 2-, 3-, and 5-year local control were 41.9%, 21.2%, 3.7%, and 3.7%, respectively. Univariate analysis showed that the local control in D90≥120 Gy group had an increasing tendency, but no statistical difference were found. The effect of local control in the squamous cell carcinoma group was slightly worse than that in the non-squamous cell carcinoma group (P=0.032). Multi-factor analysis showed that the effect of local control in the squamous cell carcinoma group was slightly poor (P=0.03). The median survival time was 14 months (95% CI 14.4-35.8 months), and the 1-, 2-, 3- and 5-year survival rate were 51.5%, 34.2%, 19.4%, and 19.4%, respectively. The three factors, such as the tumor responses, KPS status before the seed implantation, and the D90 after the seed implantation, had a tendency to improve the total survival, but there was still no statistical differences. Multivariate analysis showed no clear influence factors. Conclusions: Interstitial permanent Iodine-125 seed implantation is an effective salvage re-irradiation modality for recurrent head and neck carcinoma after previous surgery and/or EBRT. CT image-guided method could yield the reliable seeds configuration and accurate dose distribution.

Effect of Margin Size and Image Guidance Method on Biochemical Failure and Toxicity in Prostate Cancer Treated with IMRT

Effect of Margin Size and Image Guidance Method on Biochemical Failure and Toxicity in Prostate Cancer Treated with IMRT

Accuracy assessment of a\xa0potential clinical use of navigation-guided intra-operative liver metastasis brachytherapy\u2014a\xa0planning study

For patients with inoperable liver metastases, intra-operative liver high dose-rate brachytherapy (HDR-BT) is a promising technology enabling delivery of a high radiation dose to the tumor, while sparing healthy tissue. Liver brachytherapy has been described in the literature as safe and effective for the treatment of primary or secondary hepatic malignancies. It is preferred over other ablative techniques for lesions that are either larger than 4 cm or located in close proximity to large vessels or the common bile duct. In contrast to external beam radiation techniques, organ movements do not affect the size of the irradiated volume in intra-operative HDR-BT and new technical solutions exist to support image guidance for intra-operative HDR-BT. We have retrospectively analyzed anonymized CT datasets of 5 patients who underwent open liver surgery (resection and/or ablation) in order to test whether the accuracy of a new image-guidance method specifically adapted for intra-operative HDR-BT is high enough to use it in similar situations and whether patients could potentially benefit from navigation-guided intra-operative needle placement for liver HDR-BT.

A pre-operative planning framework for global registration of laparoscopic ultrasound to CT images

PurposeLaparoscopic ultrasound (LUS) enhances the safety of laparoscopic liver resection by enabling real-time imaging of internal structures such as vessels. However, LUS probes can be difficult to use, and many tumours are iso-echoic and hence are not visible. Registration of LUS to a pre-operative CT or MR scan has been proposed as a method of image guidance. However, the field of view of the probe is very small compared to the whole liver, making the registration task challenging and dependent on a very accurate initialisation.MethodsWe propose the use of a subject-specific planning framework that provides information on which anatomical liver regions it is possible to acquire vascular data that is unique enough for a globally optimal initial registration. Vessel-based rigid registration on different areas of the pre-operative CT vascular tree is used in order to evaluate predicted accuracy and reliability.ResultsThe planning framework is tested on one porcine subject where we have taken 5 independent sweeps of LUS data from different sections of the liver. Target registration error of vessel branching points was used to measure accuracy. Global registration based on vessel centrelines is applied to the 5 datasets. In 3 out of 5 cases registration is successful and in agreement with the planning. Further tests with a CT scan under abdominal insufflation show that the framework can provide valuable information in all of the 5 cases.ConclusionsWe have introduced a planning framework that can guide the surgeon on how much LUS data to collect in order to provide a reliable globally unique registration without the need for an initial manual alignment. This could potentially improve the usability of these methods in clinic.

Multiple ultrasound cavitation-enabled treatments for myocardial reduction

BackgroundUltrasound myocardial cavitation enabled treatment (MCET) is an image-guided method for tissue reduction. In this study, a strategy of fractionated (multiple) treatments was tested for efficacy.MethodsDahl SS rats were anesthetized and prepared for treatment with a focused ultrasound transducer in a warm water bath. Aiming at the anterior left ventricular wall was facilitated by imaging with a 10 MHz phased array (10S, GE Vivid 7, GE Vingmed Ultrasound, Horten, Norway). MCET was accomplished at 1.5 MHz by pulse bursts of 4 MPa peak rarefactional pressure amplitude, which were intermittently triggered 1:8 from the ECG during infusion of a microbubble suspension for cavitation nucleation. Test groups were sham, a 200 s treatment, three 200 s treatments a week apart, and a 600 s treatment. Treatment outcome was observed by plasma troponin after 4 h, echocardiographic monitoring and histology at 6 wk.ResultsThe impacts of the fractionated treatments summed to approximately the same as the long treatment; e. g. the troponin result was 10.5 ± 3.2 for 200 s, 22.7 ± 5.4 (p < 0.001) for the summed fractionated treatments and 29.9 ± 6.4 for 600 s (p = 0.06 relative to the summed fractionated). While wall thickness was not reduced for the fractionated treatment, tissue strain was reduced by 35% in the target area relative sham (p < 0.001).ConclusionThe ability to fractionate treatment may be advantageous for optimizing patient outcome relative to all-or nothing therapy by surgical myectomy or alcohol ablation.

Toward computer-assisted image-guided congenital heart defect repair: an initial phantom analysis

Radiation exposure in interventional cardiology is an important consideration, due to risk of cancer and other morbidity to the patient and clinical staff. Cardiac catheterizations rely heavily on fluoroscopic imaging exposing both patient and clinician to ionizing radiation. An image-guided surgery system capable of facilitating cardiac catheterizations was developed and tested to evaluate dose reduction. Several electromagnetically tracked tools were constructed specifically a 7-Fr catheter with five 5-degree-of-freedom magnetic seeds. Catheter guidance was accomplished using our image guidance system Kit for Navigation by Image-Focused Exploration and fluoroscopy alone. A cardiac phantom was designed and 3D printed to validate the image guidance procedure. In mock procedures, an expert clinician guided and deployed an occluder across the septal defect of the phantom heart. The image guidance method resulted in a dose of 1.26mSv of radiation dose per procedure, while traditional guidance resulted in a dose of 3.33mSv. Average overall dose savings for the image-guided method was nearly 2.07mSv or 62%. The work showed significant ([Formula: see text]) decrease in radiation dose with use of image guidance methods at the expense of a modest increase in procedure time. This study lays the groundwork for further exploration of image guidance applications in pediatric cardiology.

Abstract LB-355: Image-guided genomics reveals a symbiotic relationship between heterogeneous phenotypes in collective cancer invasion

Abstract During tumor metastasis, cancer cells invade as a phenotypically heterogeneous collective pack to navigate the tumor microenvironment. Leader cells pioneer invasion into the microenvironment whereas follower cells immediately attach to and follow the leaders. To dissect the molecular mechanisms underlying this phenotypic heterogeneity, we developed a technique termed spatiotemporal genomic and cellular analysis (SaGA), which uses image-guided genomics to precisely select living, rare cell subpopulations that are maintained within a physiologically relevant environment for downstream genomic and molecular analyses. In this manner, we can precisely select, isolate, and amplify any living cell based upon phenotypic criteria. Using H1299 lung cancer cells, we precisely selected as few as 10 leader cells using the SaGA technique and extracted them from the bulk of a multicellular cancer spheroid embedded within a 3-D matrix. These isolated cells were used to create the first leader and follower purified cell cultures. The purified leader cell cultures continually show dynamic invasive patterns over time, while follower cells alone have limited invasive capabilities. Reintroducing limited numbers of leader cells, or even leader cell conditioned media, into follower cell cultures promoted invasion and motility in the follower cells. Gene expression analysis comparing leader versus follower cell lines showed significant enrichment in cell adhesion and vascular endothelial growth factor (VEGF) signaling pathways in leader cells. This was confirmed by protein analysis showing that leader cells secrete high levels of VEGF, and VEGF inhibition abolished leader-follower collective invasion, suggesting vascularity sprouting mimicry during chain formation. Additional analysis confirmed that leader cells utilize focal adhesion kinase-fibronectin signaling to create tension force to promote chain motility. While leader cells provide an escape mechanism for followers, follower cells in turn provide leaders with increased proliferation and survival. These data support a symbiotic model of collective invasion where different cell subtypes cooperate to promote successful escape. Overall, our data demonstrate that SaGA can precisely select living cells based upon dynamic behaviors for genomic analysis and can amplify rare cell populations for subsequent molecular, cellular, and proteomic analyses. Therefore, this image-guided method has the potential to impact the field of tumor heterogeneity by uncovering genomic signatures of rare yet dynamic subpopulations within a heterogeneous cancer population. Citation Format: Jessica Konen, Emily Summerbell, Kornelia Galior, Bhakti Dwivedi, Khalid Salaita, Jeanne Kowalski, Adam Marcus. Image-guided genomics reveals a symbiotic relationship between heterogeneous phenotypes in collective cancer invasion. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-355.

Histotripsy Thrombolysis on Retracted Clots

Retracted blood clots have been previously recognized to be more resistant to drug-based thrombolysis methods, even with ultrasound and microbubble enhancements. Microtripsy, a new histotripsy approach, has been investigated as a non-invasive, drug-free and image-guided method that uses ultrasound to break up clots with improved treatment accuracy and a lower risk of vessel damage compared with the traditional histotripsy thrombolysis approach. Unlike drug-mediated thrombolysis, which is dependent on the permeation of the thrombolytic agents into the clot, microtripsy controls acoustic cavitation to fractionate clots. We hypothesize that microtripsy thrombolysis is effective on retracted clots and that the treatment efficacy can be enhanced using strategies incorporating electronic focal steering. To test our hypothesis, retracted clots were prepared in vitro and the mechanical properties were quantitatively characterized. Microtripsy thrombolysis was applied on the retracted clots in an in vitro flow model using three different strategies: single-focus, electronically-steered multi-focus and dual-pass multi-focus. Results show that microtripsy was used to successfully generate a flow channel through the retracted clot and the flow was restored. The multi-focus and the dual-pass treatments incorporating the electronic focal steering significantly increased the recanalized flow channel size compared to the single-focus treatments. The dual-pass treatments achieved a restored flow rate up to 324 mL/min without cavitation contacting the vessel wall. The clot debris particles generated from microtripsy thrombolysis remained within the safe range. The results of this study show the potential of microtripsy thrombolysis for retracted clot recanalization with the enhancement of electronic focal steering.

Abstract A61: A novel image-guided genomics approach to dissect the mechanisms of collective cancer cell invasion

Abstract During tumor metastasis, cancer cells invade as a collective pack to navigate the tumor microenvironment. In experimental models, this collective pack is phenotypically heterogenous and contains leader cells which pioneer invasion into the microenvironment and follower cells that immediately attach to and follow the leaders. To dissect the molecular mechanisms underlying this phenotypic heterogeneity, we developed a technique termed spatiotemporal genomic and cellular analysis (SAGA), which uses image-guided genomics to precisely select living, rare cell populations that are maintained within a physiologically relevant environment for downstream genomic and molecular analyses. In this manner, we can select, isolate, and amplify any living cell based upon phenotypic criteria. Using 3-D H1299 lung cancer cell spheroids, we precisely selected as few as 10 leader cells using the SAGA technique and extracted them from the bulk of a multicellular cancer spheroid embedded within a 3-D matrix. These isolated cells were used to create the first leader and follower purified cell cultures. The purified leader cell cultures continually show dynamic invasive patterns over time, while follower cells alone have limited invasive capabilities. Reintroducing limited numbers of leader cells, or even leader cell conditioned media, into follower cell cultures promoted invasion and motility in the follower cells. Genomic analysis comparing leader versus follower cell lines show significant enrichment in cell adhesion and vascular endothelial growth factor (VEGF) signaling pathways in leader cells. This was confirmed by protein analysis showing that leader cells secrete significantly higher levels of VEGF compared to follower cells, and VEGF inhibition abolished leader-follower collective invasion. Overall, our data show that SAGA can precisely select living cells based upon dynamic behaviors for genomic analysis and can amplify rare cell populations for subsequent molecular, cellular, and proteomic analyses. Therefore, this image-guided method has the potential to impact the field of tumor heterogeneity by uncovering genomic signatures of rare yet dynamic subpopulations within a heterogeneous cancer population. Citation Format: Jessica Konen, Bhakti Dwivedi, Jeanne Kowalski, Adam Marcus. A novel image-guided genomics approach to dissect the mechanisms of collective cancer cell invasion. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A61.

Real-Time 3D Image Guidance Using a Standard LINAC: Measured Motion, Accuracy, and Precision of the First Prospective Clinical Trial of Kilovoltage Intrafraction Monitoring–Guided Gating for Prostate Cancer Radiation Therapy

Kilovoltage intrafraction monitoring (KIM) is a new real-time 3-dimensional image guidance method. Unlike previous real-time image guidance methods, KIM uses a standard linear accelerator without any additional equipment needed. The first prospective clinical trial of KIM is underway for prostate cancer radiation therapy. In this paper we report on the measured motion accuracy and precision using real-time KIM-guided gating. Imaging and motion information from the first 200 fractions from 6 patient prostate cancer radiation therapy volumetric modulated arc therapy treatments were analyzed. A 3-mm/5-second action threshold was used to trigger a gating event where the beam is paused and the couch position adjusted to realign the prostate to the treatment isocenter. To quantify the in vivo accuracy and precision, KIM was compared with simultaneously acquired kV/MV triangulation for 187 fractions. KIM was successfully used in 197 of 200 fractions. Gating events occurred in 29 fractions (14.5%). In these 29 fractions, the percentage of beam-on time, the prostate displacement was >3 mm from the isocenter position, reduced from 73% without KIM to 24% with KIM-guided gating. Displacements >5 mm were reduced from 16% without KIM to 0% with KIM. The KIM accuracy was measured at <0.3 mm in all 3 dimensions. The KIM precision was <0.6 mm in all 3 dimensions. Clinical implementation of real-time KIM image guidance combined with gating for prostate cancer eliminates large prostate displacements during treatment delivery. Both in vivo KIM accuracy and precision are well below 1 mm.

Establishment of quality control evaluation system for 3D-ultrasound-based image-guided radiotherapy

Objective To analyze the stability and accuracy of the equipment for three-dimensional ultrasound-based image-guided radiation therapy (3DUS-IGRT) in daily practice, and to provide a basis for clinical application of radiotherapy for soft tissue tumors. Methods A specific calibration phantom was used for continuous calibration and quality control of the 3DUS-IGRT equipment in a year. The method for daily quality control of ultrasound-guided equipment was explored, and its stability and accuracy were monitored. Results The phantom position errors in both Sim and Guide stations of the 3DUS-IGRT equipment were within 1 mm. Conclusions The 3DUS-IGRT equipment has a stable performance with the support of a complete set of stringent and accurate calibration and quality control, which provides a new image-guided method for precise radiotherapy for soft tissue tumors. Key words: Three-dimensional ultrasound; Image-guided radiation therapy; Quality control; Phantom

3D超音波装置を用いたバスキュラーアクセス穿刺法の検討 両手穿刺を可能とするプローブ保持機構と手元観察システムの開発

3D超音波装置を用いたバスキュラーアクセス穿刺法の検討 両手穿刺を可能とするプローブ保持機構と手元観察システムの開発

Comparative Oncology: Evaluation of 2-Deoxy-2-[18F]fluoro-D-glucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) for the Staging of Dogs with Malignant Tumors.

Introduction2-Deoxy-2-[18F]fluoro-D-glucose PET/CT is a well-established imaging method for staging, restaging and therapy-control in human medicine. In veterinary medicine, this imaging method could prove to be an attractive and innovative alternative to conventional imaging in order to improve staging and restaging. The aim of this study was both to evaluate the effectiveness of this image-guided method in canine patients with spontaneously occurring cancer as well as to illustrate the dog as a well-suited animal model for comparative oncology.MethodsTen dogs with various malignant tumors were included in the study and underwent a whole body FDG PET/CT. One patient has a second PET-CT 5 months after the first study. Patients were diagnosed with histiocytic sarcoma (n = 1), malignant lymphoma (n = 2), mammary carcinoma (n = 4), sertoli cell tumor (n = 1), gastrointestinal stromal tumor (GIST) (n = 1) and lung tumor (n = 1). PET/CT data were analyzed with the help of a 5-point scale in consideration of the patients’ medical histories.ResultsIn seven of the ten dogs, the treatment protocol and prognosis were significantly changed due to the results of FDG PET/CT. In the patients with lymphoma (n = 2) tumor extent could be defined on PET/CT because of increased FDG uptake in multiple lymph nodes. This led to the recommendation for a therapeutic polychemotherapy as a treatment. In one of the dogs with mammary carcinoma (n = 4) and in the patient with the lung tumor (n = 1), surgery was cancelled due to the discovery of multiple metastasis. Consequently no treatment was recommended.ConclusionFDG PET/CT offers additional information in canine patients with malignant disease with a potential improvement of staging and restaging. The encouraging data of this clinical study highlights the possibility to further improve innovative diagnostic and staging methods with regard to comparative oncology. In the future, performing PET/CT not only for staging but also in therapy control could offer a significant improvement in the management of dogs with malignant tumors.

Microrecording and image-guided stereotactic biopsy of deep-seated brain tumors.

Image-guided stereotactic brain tumor biopsy cannot easily obtain samples of small deep-seated tumor or selectively sample the most viable region of malignant tumor. Image-guided stereotactic biopsy in combination with depth microrecording was evaluated to solve such problems. Operative records, MRI findings, and pathological specimens were evaluated in 12 patients with small deep-seated brain tumor, in which image-guided stereotactic biopsy was performed with the aid of depth microrecording. The tumors were located in the caudate nucleus (1 patient), thalamus (7 patients), midbrain (2 patients), and cortex (2 patients). Surgery was performed with a frameless stereotactic system in 3 patients and with a frame-based stereotactic system in 9 patients. Microrecording was performed to study the electrical activities along the trajectory in the deep brain structures and the tumor. The correlations were studied between the electrophysiological, MRI, and pathological findings. Thirty-two patients with surface or large brain tumor were also studied, in whom image-guided stereotactic biopsy without microrecording was performed. The diagnostic yield in the group with microrecording was 100% (low-grade glioma 4, high-grade glioma 4, diffuse large B-cell lymphoma 3, and germinoma 1), which was comparable to 93.8% in the group without microrecording. The postoperative complication rate was as low as that of the conventional image-guided method without using microelectrode recording, and the mortality rate was 0%, although the target lesions were small and deep-seated in all cases. Depth microrecording revealed disappearance of neural activity in the tumor regardless of the tumor type. Neural activity began to decrease from 6.3 ± 4.5 mm (mean ± SD) above the point of complete disappearance along the trajectory. Burst discharges were observed in 6 of the 12 cases, from 3 ± 1.4 mm above the point of decrease of neural activity. Injury discharges were often found at 0.5-1 mm along the trajectory between the area of decreased and disappeared neural activity. Close correlations between electrophysiological, MRI, and histological findings could be found in some cases. Image-guided stereotactic biopsy performed using depth microrecording was safe, it provided accurate positional information in real time, and it could distinguish the tumor from brain structures during surgery. Moreover, this technique has potential for studying the epileptogenicity of the brain tumor.

The first clinical treatment with kilovoltage intrafraction monitoring (KIM): a real-time image guidance method.

Kilovoltage intrafraction monitoring (KIM) is a real-time image guidance method that uses widely available radiotherapy technology, i.e., a gantry-mounted x-ray imager. The authors report on the geometric and dosimetric results of the first patient treatment using KIM which occurred on September 16, 2014. KIM uses current and prior 2D x-ray images to estimate the 3D target position during cancer radiotherapy treatment delivery. KIM software was written to process kilovoltage (kV) images streamed from a standard C-arm linear accelerator with a gantry-mounted kV x-ray imaging system. A 120° pretreatment kV imaging arc was acquired to build the patient-specific 2D to 3D motion correlation. The kV imager was activated during the megavoltage (MV) treatment, a dual arc VMAT prostate treatment, to estimate the 3D prostate position in real-time. All necessary ethics, legal, and regulatory requirements were met for this clinical study. The quality assurance processes were completed and peer reviewed. During treatment, a prostate position offset of nearly 3 mm in the posterior direction was observed with KIM. This position offset did not trigger a gating event. After the treatment, the prostate motion was independently measured using kV/MV triangulation, resulting in a mean difference of less than 0.6 mm and standard deviation of less than 0.6 mm in each direction. The accuracy of the marker segmentation was visually assessed during and after treatment and found to be performing well. During treatment, there were no interruptions due to performance of the KIM software. For the first time, KIM has been used for real-time image guidance during cancer radiotherapy. The measured accuracy and precision were both submillimeter for the first treatment fraction. This clinical translational research milestone paves the way for the broad implementation of real-time image guidance to facilitate the detection and correction of geometric and dosimetric errors, and resultant improved clinical outcomes, in cancer radiotherapy.

Real Time Target Tracking in a Phantom Using Ultrasonic Imaging

In this paper we present a real-time ultrasound image guidance method suitable for tracking the motion of tumors. A 2D ultrasound based motion tracking system was evaluated. A robot was used to control the focused ultrasound and position it at the target that has been segmented from a real-time ultrasound video. Tracking accuracy and precision were investigated using a lesion mimicking phantom. Experiments have been conducted and results show sufficient efficiency of the image guidance algorithm. This work could be developed as the foundation for combining the real time ultrasound imaging tracking and MRI thermometry monitoring non-invasive surgery.

Feasibility of the combination of 3D CTA and 2D CT imaging guidance for clipping microsurgery of anterior communicating artery aneurysm

Objective. We report the technique of three-dimensional computed tomography angiography (3D CTA) + two-dimensional computed tomographic (2D CT) imaging as an adjunct in early surgery for a ruptured anterior communicating artery (ACoA) aneurysm by adopting an anterior interhemispheric approach. These combined imaging modalities provide accurate intraoperative anatomical information. Methods. To produce images for an anterior interhemispheric approach, 3D CTA + 2D coronal CT images, which are perpendicular to the direction of the surgical approach at three levels (brain surface, genu of the corpus callosum and aneurysm neck), were constructed. We also produced two 3D CTA + 2D CT images of the lamina terminalis, with a horizontal 10-degree difference, to clarify the vascular architecture around the aneurysm stereotactically, as well as the dissection point and direction to open the lamina terminalis. Furthermore, we produced a 3D CTA + 2D sagittal CT image at the midline, which allowed us to understand the anatomical architecture of the aneurysm, planum sphenoidale and tuberculum sellae. In addition, four different 3D CTA aneurysm images were produced for deciding the clip size preoperatively. Results. The imaging findings in 28 patients with 28 ACoA aneurysms facilitated early clipping. Based on these 3D CTA + 2D CT images, we conducted aneurysm surgery, and successfully performed neck clipping via an anterior interhemispheric approach. Conclusion. The combination of 3D CTA and 2D CT images is a feasible and useful method of image guidance for ACoA aneurysm microsurgery.

Augmenting interventional ultrasound using statistical shape model for guiding percutaneous nephrolithotomy: Initial evaluation in pigs

Successful percutaneous nephrolithotomy (PCNL) highly depends on an accurate needle puncture of the kidney. This puncture step is challenging and must be performed under intraoperative image guidance. This paper presents an image guidance method for PCNL by augmenting interventional ultrasound (US) using a 3D statistical kidney model. First, a 3D statistical kidney model is built aforehand from a collection of aligned training shapes. Intraoperatively, a patient-specific 3D kidney model is reconstructed in a fine-tune way using sparse manually picked points from calibrated US at maximum exhalation. The US images are then augmented with the kidney model and a real-time tracked virtual needle. Under the augmented-US guidance, percutaneous renal puncture can be performed. Experiments results based on Wuzhishan pig data have validated the accuracy and inter-operator repeatability of the presented kidney model reconstruction. The feasibility and efficiency of the proposed augmented US-guided puncture for PCNL have been demonstrated in pigs. With careful setup by trained surgeons, our proposed guidance has the potential to reduce the occurrence of complications such as PCS access failure and bleeding compared with a traditional US-guided method.

Use of 4D-CBCT to Assess Target and Organ Motion in Esophageal Cancer Patients

Radiotherapy for esophageal cancer is challenged by intra-fractional organ movement. Daily image guidance is used to assess patient set-up errors and correct for positional offsets of the target and organs at risk. There exists a paucity of published data on four-dimensional cone-beam computed tomography (4D-CBCT) as a method of image guidance for these patients. This study utilized 4D-CBCTs to compare the efficacy of different registration volumes (bone, internal target volume (ITV), carina) for image guidance with focus on whether carina is a useful ITV surrogate. The study also assessed our centre's current planning target volume (PTV) margins of 0.5 cm around the ITV. This retrospective study involved 17 esophageal cancer patients treated radically from July 2012-July 2013 using volumetric-modulated arc therapy. Daily CBCTs (402) were reconstructed into 4D Medium Resolution 8-phase 4D-CBCTs using Elekta XVI software and registered to the helical CT simulation scan in voluntary exhale. Two separate dual registration matches were done; the first registered a clipbox around the vertebrae and a mask around the ITV, and the second used carina as the mask. T-test was used to test for significant difference between X,Y,Z-offsets; means and standard deviations were calculated. For each directional shift, the average difference in amplitude (absolute value of maximum inhale plus maximum exhale) between 4DCT and 4D-CBCT was determined. In some comparisons of vertebrae/ITV/carina mean offsets, statistical significance was found (t-test, p=0.05). However, only comparison of vertebrae and ITV mean offsets revealed clinical significance for the Y-dimension with the magnitude being >0.2 cm. For 14 patients (3 excluded due to unavailable data), average difference in amplitude between 4DCT and 4D-CBCT in the X,Y,Z-directions were determined to be 0.12 cm, -0.05 cm, and 0.04 cm, respectively. In 8.4% of the cases, movement of the ITV in the Y-direction was greater than the PTV margin. Carina appears to be a better ITV surrogate versus vertebrae for image guidance on 4D-CBCTs in the Y-dimension. In the majority of cases, PTV margins are sufficient for target coverage. Future research on patient-specific indicators for significant ITV movement in the Y-direction is needed.

Applications of Intraoperative Ultrasound in Epilepsy Surgery for Focal Cortical Dysplasia

The definite margins of focal cortical dysplasias (FCDs) are usually not clear, and all epileptic surgeons have tried to identify them by advanced navigation, fusing magnetic resonance imaging and positron emission tomography, intraoperative magnetic resonance imaging, and intraoperative mapping in past decades. In this report, we present a convenient tool to define the boundary of FCD and improve the surgical outcome. The safe and effective method of image guidance by intraoperative ultrasound was demonstrated, and is time-saving and of a high resolution. In the future, intraoperative ultrasound will be useful in defining subtle epileptogenic lesions, especially when the surgeons encounter FCDs.