Tomography Fusion Imaging Research Articles

Multimodality Image-Guided Sclerotherapy of Low-Flow Orbital Vascular Malformations: Report of Single-Center Experience

PurposeTo evaluate the role of multimodality imaging tools for intraprocedural guidance and outcome evaluation during sclerotherapy of low-flow orbital vascular malformations. Materials and MethodsA retrospective review was performed of 17 consecutive patients with low-flow orbital malformations (14 lymphatic, two venous, and one venolymphatic) who underwent multimodality image-guided sclerotherapy between November 2012 and May 2015. Sclerotherapy technique, image guidance tools, and complications were recorded. Sclerotherapy outcome was evaluated using clinical response, magnetic resonance (MR) image–based lesion volumetry, and proptosis quantification. ResultsThere were 22 sclerotherapy sessions performed. Intraprocedural ultrasound (US), fluoroscopy, cone-beam computed tomography (CT) and MR image fusion were used for image guidance with 100% technical success. Resolution of presenting symptoms was observed in all patients at 1-month follow-up. Four major sclerotherapy complications were successfully managed. Statistically significant reduction in lesion volume (P = .001) and proptosis (P = .0117) by MR image analysis was achieved in all patients in whom 3-month follow-up MR imaging was available (n = 13/17). There was no lesion recurrence at a median follow-up of 18 months (range, 8–38 mo). ConclusionsMultimodality imaging tools, including US, fluoroscopy, cone-beam CT, and MR fusion, during sclerotherapy of low-flow orbital malformations provide intraprocedural guidance and quantitative image-based evaluation of treatment outcome.

Significance of functional hepatic resection rate calculated using 3D CT/(99m)Tc-galactosyl human serum albumin single-photon emission computed tomography fusion imaging.

To evaluate the usefulness of the functional hepatic resection rate (FHRR) calculated using 3D computed tomography (CT)/(99m)Tc-galactosyl-human serum albumin (GSA) single-photon emission computed tomography (SPECT) fusion imaging for surgical decision making. We enrolled 57 patients who underwent bi- or trisectionectomy at our institution between October 2013 and March 2015. Of these, 26 patients presented with hepatocellular carcinoma, 12 with hilar cholangiocarcinoma, six with intrahepatic cholangiocarcinoma, four with liver metastasis, and nine with other diseases. All patients preoperatively underwent three-phase dynamic multidetector CT and (99m)Tc-GSA scintigraphy. We compared the parenchymal hepatic resection rate (PHRR) with the FHRR, which was defined as the resection volume counts per total liver volume counts on 3D CT/(99m)Tc-GSA SPECT fusion images. In total, 50 patients underwent bisectionectomy and seven underwent trisectionectomy. Biliary reconstruction was performed in 15 patients, including hepatopancreatoduodenectomy in two. FHRR and PHRR were 38.6 ± 19.9 and 44.5 ± 16.0, respectively; FHRR was strongly correlated with PHRR. The regression coefficient for FHRR on PHRR was 1.16 (P < 0.0001). The ratio of FHRR to PHRR for patients with preoperative therapies (transcatheter arterial chemoembolization, radiation, radiofrequency ablation, etc.), large tumors with a volume of > 1000 mL, and/or macroscopic vascular invasion was significantly smaller than that for patients without these factors (0.73 ± 0.19 vs 0.82 ± 0.18, P < 0.05). Postoperative hyperbilirubinemia was observed in six patients. Major morbidities (Clavien-Dindo grade ≥ 3) occurred in 17 patients (29.8%). There was no case of surgery-related death. Our results suggest that FHRR is an important deciding factor for major hepatectomy, because FHRR and PHRR may be discrepant owing to insufficient hepatic inflow and congestion in patients with preoperative therapies, macroscopic vascular invasion, and/or a tumor volume of > 1000 mL.

Three-Dimensional Visualization of Ligamentum Flavum Relative to the Affected Spinal Nerve Root by MRI/CT Fusion Imaging: Three Case Reports of Lumbar Radiculopathy and Motor Palsy

The objective of this study was to introduce a technique that enables the virtual anatomy of the ligamentum flavum (LF) to be assessed using 3D magnetic resonance (MR)/computed tomography (CT) fusion images that show the compression of the lumbar nerve root by both the herniated disc and the LF at the lateral canal zone or the foraminal zone in patients with lumbar radiculopathy or motor palsy. MR and CT images were obtained from three patients with lumbar radiculopathy with or without lower limb motor palsy. The most important characteristic evident on the images was flattening of the nerve root related to the LF, likely resulting from degenerative changes. Occasionally, the LF may play a role in root compression. In cases of motor palsy secondary to a herniated disc, the affected root was compressed with tortuosity. The flattened portion of the root seemed to change the angle of its path. In the case with lateral canal stenosis, the root was observed to be compressed between the disc and LF, resulting in constriction. In the case of degenerative lumbar scoliosis, abnormal complicated paths are seen as a result of vertebral rotation, which can change the angle of the nerve root path twice. The 3D MR/CT fusion imaging technique enhances visualization of the pathoanatomy in an otherwise blind area in the lumbar spine that is composed of the root and intervertebral foramen. Clinicians can more clearly identify the narrowest portion of the root using this 3D visualization of both the LF and disc.

Ultrasound Computed Tomography Image Fusion- Guided Radiofrequency Ablation for Difficult Hepatocellular Carcinoma: A Case Report

Ultrasound is a widely used tool for screening and treating hepatocellular carcinoma (HCC) to prolong patient survival, particularly for those who are unable to undergo surgery. Although ultrasound is less expensive and highly accessible, the use of ultrasound alone is sometimes limited in terms of detecting tumors with isoechogenicity, thus hampering further ultrasound-guided therapy. Here, we report a 64-year-old man with chronic hepatitis C-related cirrhosis. A 1-cm HCC was detected during an abdominal computed tomography assessment. Two attempts at ultrasound-guided radiofrequency ablation failed to target the lesion because of the inaccurate localization of the lesion using ultrasound alone. After the introduction of an ultrasound image fusion system in the hospital, the third attempt at radiofrequency ablation of the tumor was successful. Therefore, this case study suggests the use of an ultrasound image fusion system to improve treatment outcomes in complicated HCC cases.

Value of C-Arm Cone Beam Computed Tomography Image Fusion in Maximizing the Versatility of Endovascular Robotics

To report our initial experience and highlight the value of using intraoperative C-arm cone beam computed tomography (CT; DynaCT(®)) image fusion guidance along with steerable robotic endovascular catheter navigation to optimize vessel cannulation. Between May 2013 and January 2015, all patients who underwent endovascular procedures using DynaCT image fusion technique along with Hansen Magellan vascular robotic catheter were included in this study. As a part of preoperative planning, relevant vessel landmarks were electronically marked in contrast-enhanced multi-slice computed tomography images and stored. At the beginning of procedure, an intraoperative noncontrast C-arm cone beam CT (syngo DynaCT(®), Siemens Medical Solutions USA Inc.) was acquired in the hybrid suite. Preoperative images were then coregistered to intraoperative DynaCT images using aortic wall calcifications and bone landmarks. Stored landmarks were then overlaid on 2-dimensional (2D) live fluoroscopic images as virtual markers that are updated in real-time with C-arm, table movements and image zoom. Vascular access and robotic catheter (Magellan(®), Hansen Medical) was setup per standard. Vessel cannulation was performed based on electronic virtual markers on live fluoroscopy using robotic catheter. The impact of 3-dimensional (3D) image fusion guidance on robotic vessel cannulation was evaluated retrospectively, by assessing quantitative parameters like number of angiograms acquired before vessel cannulation and qualitative parameters like accuracy of vessel ostium and centerline markers. All 17 vessels were cannulated successfully in 14 patients' attempted using robotic catheter and image fusion guidance. Median vessel diameter at origin was 5.4 mm (range, 2.3-13 mm), whereas 12 of 17 (70.6%) vessels had either calcified and/or stenosed origin from parent vessel. Nine of 17 vessels (52.9 %) were cannulated without any contrast injection. Median number of angiograms required before cannulation was 0 (range, 0-2). On qualitative assessment, 14 of 15 vessels (93.3%) had grade = 1 accuracy (guidewire inside virtual ostial marker). Fourteen of 14 vessels had grade = 1 accuracy (virtual centerlines that matched with the actual vessel trajectory during cannulation). In this small series, the experience of using DynaCT image fusion guidance together with a steerable endovascular robotic catheter indicates that such image fusion strategies can enhance intraoperative 2D fluoroscopy by bringing preoperative 3D information about vascular stenosis and/or calcification, angulation, and take off from main vessel thereby facilitating ultimate vessel cannulation.

Urgent endovascular repair for ruptured aortic aneurysm using computed tomography image fusion

Abdominal aortic aneurysm rupture remains a cardiovascular catastrophe with strikingly high morbidity and mortality rates. Endovascular aneurysm repair management has recently emerged as a valuable treatment modality for ruptured abdominal aortic aneurysm, but better outcomes have to be reached. Image fusion may potentially improve perioperative outcomes in selected patients, guiding navigation and device implantation and limiting contrast dosage during interventions. We report an 83-year-old man presenting with an 80-mm infrarenal aortic aneurysm rupture suitable for endovascular aneurysm repair. Endovascular navigation and stent graft deployment were achieved using computed tomography image fusion for the first reported case in English.

Effect of branched-chain amino acid supplementation on functional liver regeneration in patients undergoing portal vein embolization and sequential hepatectomy: a randomized controlled trial.

Portal vein embolization (PVE) can decrease the resection ratio for major hepatectomy. (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy is useful for evaluating quantitative functional liver volume. Branched chain amino acids (BCAAs) modulate liver function and regeneration. We analyzed the effects of BCAAs, in terms of liver function and regeneration after PVE, in combination with major hepatectomy. This randomized controlled trial was conducted for patients receiving PVE through to complete hepatectomy from September, 2011 to June, 2013. BCAA granules were added two times a day to a conventional diet in the BCAA administration group (BCAA group). The primary end point was functional liver regeneration of the future remnant liver after PVE followed by hepatic resection. Functional liver regeneration was assessed by the liver uptake value obtained from (99m)Tc-GSA scintigraphy single-photon-emission computed tomography/computed tomography fusion images. The secondary end points were volumetric liver regeneration and changes in liver function and laboratory data. A BCAA group (n = 13) and a non-BCAA group (control group; n = 15) were included. The primary end point was partially met: the liver uptake value significantly increased in the BCAA group compared with the control group 6 months after hepatic resection (266.7% vs 77.6%, P = 0.04) and marginally increased after PVE (43.8% vs 17.4%, P = 0.079). Following PVE, the increment of the uptake ratio of the liver to the liver plus heart at 15 min was significantly less in the BCAA group than in the control group (0.0 and 0.01, P = 0.023). BCAA supplementation improved functional liver regeneration and function in patients undergoing PVE followed by major hepatic resection.

A measure to assess the ablative margin using 3D-CT image fusion after radiofrequency ablation of hepatocellular carcinoma

ObjectivesTo examine the feasibility of three-dimensional computed tomography (3D-CT) image fusion in facilitating assessment of the ablative margin (AM) after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC). MethodsThis study involved 75 patients with solitary HCC who underwent RFA. The AM was evaluated using 3D-CT image fusion. All cases were categorized into two groups based on the extent of the AM: in Group A, sufficient AM was obtained, which was greater than or equal to 5 mm; in Group B, the lesion was also ablated successfully, but a 5 mm AM was not obtained. Results3D-CT Image Fusion was performed on 36 and 39 patients in Group A and Group B, respectively. The 1, 3, 5 year RFS was 87.6%, 63.2%, 50.6% for Group A, and 77.2%, 51.5%, 35.6% for Group B, respectively (P = 0.042); the corresponding OS was 94.3%, 73.8%, 64.6%, and 86.2%, 60.5%, 47.6%, respectively (P = 0.046). Multivariate analysis showed that the AM (P = 0.048, HR = 2.15, 95% CI 1.01–4.60) and Pre-NLR were independent prognostic factors for PFS. Conclusions3D-CT image fusion is a feasible and useful method to evaluate the AM after RFA of HCC.

Cone beam computed tomography images fusion in predicting lung ablation volumes: a feasibility study.

Recently different software with the ability to plan ablation volumes have been developed in order to minimize the number of attempts of positioning electrodes and to improve a safe overall tumor coverage. To assess the feasibility of three-dimensional cone beam computed tomography (3D CBCT) fusion imaging with "virtual probe" positioning, to predict ablation volume in lung tumors treated percutaneously. Pre-procedural computed tomography contrast-enhanced scans (CECT) were merged with a CBCT volume obtained to plan the ablation. An offline tumor segmentation was performed to determine the number of antennae and their positioning within the tumor. The volume of ablation obtained, evaluated on CECT performed after 1 month, was compared with the pre-procedural predicted one. Feasibility was assessed on the basis of accuracy evaluation (visual evaluation [VE] and quantitative evaluation [QE]), technical success (TS), and technical effectiveness (TE). Seven of the patients with lung tumor treated by percutaneous thermal ablation were selected and treated on the basis of the 3D CBCT fusion imaging. In all cases the volume of ablation predicted was in accordance with that obtained. The difference in volume between predicted ablation volumes and obtained ones on CECT at 1 month was 1.8 cm(3) (SD ± 2, min. 0.4, max. 0.9) for MW and 0.9 cm(3) (SD ± 1.1, min. 0.1, max. 0.7) for RF. Use of pre-procedural 3D CBCT fusion imaging could be useful to define expected ablation volumes. However, more patients are needed to ensure stronger evidence.

Virtual pathology of cervical radiculopathy based on 3D MR/CT fusion images: impingement, flattening or twisted condition of the compressed nerve root in three cases.

BackgroundThere have been several imaging studies of cervical radiculopathy, but no three-dimensional (3D) images have shown the path, position, and pathological changes of the cervical nerve roots and spinal root ganglion relative to the cervical bony structure. The objective of this study was to introduce a technique that enables the virtual pathology of the nerve root to be assessed using 3D magnetic resonance (MR)/computed tomography (CT) fusion images that show the compression of the proximal portion of the cervical nerve root by both the herniated disc and the preforaminal or foraminal bony spur in patients with cervical radiculopathy.FindingsMR and CT images were obtained from three patients with cervical radiculopathy. 3D MR images were placed onto 3D CT images using a computer workstation.The entire nerve root could be visualized in 3D with or without the vertebrae. The most important characteristic evident on the images was flattening of the nerve root by a bony spur. The affected root was constricted at a pre-ganglion site. In cases of severe deformity, the flattened portion of the root seemed to change the angle of its path, resulting in twisted condition.ConclusionsThe 3D MR/CT fusion imaging technique enhances visualization of pathoanatomy in cervical hidden area that is composed of the root and intervertebral foramen. This technique provides two distinct advantages for diagnosis of cervical radiculopathy. First, the isolation of individual vertebra clarifies the deformities of the whole root groove, including both the uncinate process and superior articular process in the cervical spine. Second, the tortuous or twisted condition of a compressed root can be visualized.The surgeon can identify the narrowest face of the root if they view the MR/CT fusion image from the posterolateral-inferior direction. Surgeons use MR/CT fusion images as a pre-operative map and for intraoperative navigation. The MR/CT fusion images can also be used as educational materials for all hospital staff and for patients and patients’ families who provide informed consent for treatments.

The utility of single photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging in the diagnosis of a vertebral compression fracture in multiple myeloma

The utility of single photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging in the diagnosis of a vertebral compression fracture in multiple myeloma

Real-Time Pretreatment Review Limits Unacceptable Deviations on a Cooperative Group Radiation Therapy Technique Trial: Quality Assurance Results of RTOG 0933

RTOG 0933 was a phase II trial of hippocampal avoidance during whole brain radiation therapy for patients with brain metastases. The results demonstrated improvement in short-term memory decline, as compared with historical control individuals, and preservation of quality of life. Integral to the conduct of this trial were quality assurance processes inclusive of pre-enrollment credentialing and pretreatment centralized review of enrolled patients. Before enrolling patients, all treating physicians and sites were required to successfully complete a "dry-run" credentialing test. The treating physicians were credentialed based on accuracy of magnetic resonance imaging-computed tomography image fusion and hippocampal and normal tissue contouring, and the sites were credentialed based on protocol-specified dosimetric criteria. Using the same criteria, pretreatment centralized review of enrolled patients was conducted. Physicians enrolling 3 consecutive patients without unacceptable deviations were permitted to enroll further patients without pretreatment review, although their cases were reviewed after treatment. In all, 113 physicians and 84 sites were credentialed. Eight physicians (6.8%) failed hippocampal contouring on the first attempt; 3 were approved on the second attempt. Eight sites (9.5%) failed intensity modulated radiation therapy planning on the first attempt; all were approved on the second attempt. One hundred thirteen patients were enrolled in RTOG 0933; 100 were analyzable. Eighty-seven cases were reviewed before treatment; 5 (5.7%) violated the eligibility criteria, and 21 (24%) had unacceptable deviations. With feedback, 18 cases were approved on the second attempt and 2 cases on the third attempt. One patient was treated off protocol. Twenty-two cases were reviewed after treatment; 1 (4.5%) violated the eligibility criteria, and 5 (23%) had unacceptable deviations. Although >95% of the cases passed the pre-enrollment credentialing, the pretreatment centralized review disqualified 5.7% of reviewed cases, prevented unacceptable deviations in 24% of reviewed cases, and limited the final unacceptable deviation rate to 5%. Thus, pretreatment review is deemed necessary in future hippocampal avoidance trials and is potentially useful in other similarly challenging radiation therapy technique trials.

Technological value of SPECT/CT fusion imaging for the diagnosis of lower gastrointestinal bleeding.

The aim of this study was to assess the clinical value of diagnosing and locating lower gastrointestinal (GI) bleeding using single photon emission computed tomography (SPECT)/computed tomography (CT) fusion imaging with 99mTc labeled red blood cells ((99m)Tc-RBC). Fifty-six patients with suspected lower GI bleeding received a preoperative intravenous injection of (99m)Tc-RBC and each underwent planar, SPECT/CT imaging of the lower abdominal region. The location and path of lower GI bleeding were diagnosed by contrastive analysis of planar and SPECT/CT fusion imaging. Among the 56 patients selected, there were abnormalities in concentrated radionuclide activity with planar imaging in 50 patients and in SPECT/CT fusion imaging in 52 patients. Moreover, bleeding points that were coincident with the surgical results were evident with planar imaging in 31 patients and with SPECT/CT fusion imaging in 48 patients. The diagnostic sensitivity of planar imaging and SPECT/CT fusion imaging were 89.3% (50/56) and 92.9% (52/56), respectively, and the difference was not statistically significant (χ(2) = 0.11, P > 0.05). The corresponding positional accuracy values were 73.8% (31/42) and 92.3% (48/52), and the difference was statistically significant (χ(2) = 4.63, P < 0.05). (99m)Tc- RBC SPECT/CT fusion imaging is an effective, simple, and accurate method that can be used for diagnosing and locating lower GI bleeding.

SPET–CT in thyroid cancer: a systematic review

The purpose of this study was to systematically review the utility of single-photon emission tomography–computed tomography (SPET–CT) fusion imaging in the investigation of thyroid cancer. We performed a systematic search of the world literature on radionuclide SPET–CT imaging of thyroid cancer using the medical databases Medline (OVID) and PubMed. The following search terms were used to identify relevant studies: (a) thyroid, combined with (b) SPECT/CT or SPECT–CT or SPET/CT or SPET–CT. The electronic searches returned citations for 1,189 potentially eligible articles and 98 abstracts were reviewed for relevance by two co-authors. Thirty-one peer-reviewed full articles reporting the utility, value and diagnostic performance of radioiodine SPET–CT for the imaging of well-differentiated thyroid cancer were selected. The quality of these studies was assessed using the quality assessment of diagnostic accuracy studies-2 tool. As there was heterogeneity in the studies, a systematic review analysis was conducted as our chosen research synthesis method. A total of 31 studies published between 2003 and 2014 report the utility of radioiodine SPET–CT. These studies uniformly found incremental diagnostic value of I-123 and I-131 SPET–CT over SPET and/or planar imaging. SPET–CT allows accurate characterization of radioiodine uptake in the neck and at distant sites, clarifies equivocal foci of radioactivity, improves specificity for disease, and evaluates benign physiological etiologies. Additional pilot uses of SPET–CT have been reported, e.g., for thyroid nodule evaluation, medullary thyroid cancer work-up, and investigation of lingual thyroid. Radioiodine SPET–CT fusion imaging of thyroid cancer has incremental utility, improving image interpretation as compared to planar and SPET imaging. It is likely to see more widespread application in the future.

Imaging spectrum of peritoneal carcinomatosis on FDG PET/CT.

Recognition of patterns has always been extremely important in cross-sectional imaging. Peritoneal involvement, both primary and as dissemination from abdominopelvic malignancies, is manifested in different forms, purely because of anatomical complexity. We studied series of peritoneal involvement by (18)F-fluorodeoxyglucose positron-emission tomography/computed tomography fusion imaging and derived patterns of tracer uptake on maximum intensity projection and cross-sectional fusion images.

Multi dose computed tomography image fusion based on hybrid sparse methodology.

With the increasing utilization of X-ray Computed Tomography (CT) in medical diagnosis, obtaining higher quality image with lower exposure to radiation has become a highly challenging task in image processing. In this paper, a novel sparse fusion algorithm is proposed to address the problem of lower Signal to Noise Ratio (SNR) in low dose CT images. Initial fused image is obtained by combining low dose and medium dose images in sparse domain, utilizing the Dual Tree Complex Wavelet Transform (DTCWT) dictionary which is trained by high dose image. And then, the strongly focused image is obtained by determining the pixels of source images which have high similarity with the pixels of the initial fused image. Final denoised image is obtained by fusing strongly focused image and decomposed sparse vectors of source images, thereby preserving the edges and other critical information needed for diagnosis. This paper demonstrates the effectiveness of the proposed algorithm both quantitatively and qualitatively.

Functional discrepancy between two liver lobes after hemilobe biliary drainage in patients with jaundice and bile duct cancer: an appraisal using (99m)Tc-GSA SPECT/CT fusion imaging.

To determine the functional discrepancy between the two liver lobes using technetium 99m ((99m)Tc) diethylenetriamine-pentaacetic acid-galactosyl human serum albumin ( GSA diethylenetriamine-pentaacetic acid-galactosyl human serum albumin ) single photon emission computed tomography (SPECT)/computed tomography (CT) fusion imaging following preoperative biliary drainage and portal vein embolization ( PVE portal vein embolization ) in patients with jaundice who have bile duct cancer ( BDC bile duct cancer ). This retrospective study was approved by the institutional review board, with waiver of informed consent. Preoperative (99m)Tc- GSA diethylenetriamine-pentaacetic acid-galactosyl human serum albumin SPECT/CT fusion images from 32 patients with extrahepatic BDC bile duct cancer were retrospectively reviewed. Patients were classified into four groups according to the extent of biliary drainage and presence of a preoperative right PVE portal vein embolization : right lobe drainage group (right drainage), bilateral lobe drainage group (bilateral drainage), left lobe drainage group (left drainage), and left lobe drainage with right PVE portal vein embolization group (left drainage with right PVE portal vein embolization ). Percentage volume and percentage function were measured in each lobe using fusion imaging. The ratio between percentage function and percentage volume (the function-to-volume ratio) was calculated for each lobe, and the results were compared among the four groups. Statistical analysis was performed with Wilcoxon signed-rank tests and Mann-Whitney U tests. The median values for the function-to-volume ratio in the right drainage, bilateral drainage, left drainage, and left drainage with right PVE portal vein embolization group were 1.12, 1.05, 1.02, and 0.81 in the right lobe; and 0.51, 0.88, 0.96, and 1.17 in the left lobe. Significant differences in the function-to-volume ratio were observed among the four groups (right drainage vs bilateral drainage vs left drainage vs left drainage with right PVE portal vein embolization ; with P < .002, P = .023, and P < .002 for the right lobe and P < .001, P = .023, and P < .002 for the left lobe). Hepatic lobar function significantly differs between the two lobes, depending on the extent of biliary drainage and the presence of portal vein embolization.

Electrical characterization of bolus material as phantom for use in electrical impedance and computed tomography fusion imaging

Abstract Phantoms are widely used in medical imaging to predict image quality prior to clinical imaging. This paper discusses the possible use of bolus material, as a conductivity phantom, for validation and interpretation of electrical impedance tomography (EIT) images. Bolus is commonly used in radiation therapy to mimic tissue. When irradiated, it has radiological characteristics similar to tissue. With increased research interest in CT/EIT fusion imaging there is a need to find a material which has both the absorption coefficient and electrical conductivity similar to biological tissues. In the present study the electrical properties, specifically resistivity, of various commercially available bolus materials were characterized by comparing their frequency response with that of in-vivo connective adipose tissue. It was determined that the resistivity of Gelatin Bolus is similar to in-vivo tissue in the frequency range 10 kHz to 1MHz and therefore has potential to be used in EIT/CT fusion imaging studies.

Moderne Technologien in der Mund-, Kiefer- und Gesichtschirurgie

Modern technologies are influencing medicine everyday. The oral and maxillofacial surgery meet the worlds from medicine and dentistry. So technologies from both fields are utilized. This article provides an overview about technologies in clinical use, which are typical for the specialty. Their principles and indications are described as well as benefits and limitations. Based on Cone Beam Computed Tomography image fusion and mirroring techniques are explained as well as patient specific models and implants, template guided and free surgical navigation with and without intraoperative three-dimensional imaging. An overall assessment reveals further need of research regarding indications and patient benefit.

Magnetic Resonance Imaging and Computed Tomography Image Fusion–Based Aorta and Coronary Artery Model for In Silico Feasibility Evaluation of Perfusion With an Ascending Aortic Pump Using Computational Fluid Dynamics

Left ventricular assist devices are mechanical pumps that provide full or partial support of the circulation in patients with varying degrees of heart failure. These devices are usually connected to the heart through the ventricular apex and placed in an abdominal pocket or pericardial sac, which requires open heart surgery. However, investigators have suggested advantages of catheter deployment of an intra-aortic pump, positioned in the ascending aorta using an anchoring device [1]. This simulation study explores the hemodynamic effects of a continuous flow, axial flow pump deployed in the ascending aorta (AAo), specifically focusing on: (a) perfusion of the coronary arterial circulation and (b) the effect of induced nonphysiologic, swirling flow discharged by the pump on perfusion to head-neck vessels of the aortic arch.A 3D numerical model of an adult aorta with coronary arterial branches was reconstructed by fusion of segmented vascular anatomies extracted from magnetic resonance (MR) angiography and contrast-enhanced computed tomography (CT) data resolving the coronary arteries (Fig. 1(a)). A cylindrical object, representative of the pump, was virtually positioned into the AAo with a diameter ∼2/3rd of the aortic dimension at the midplane of insertion. Incompressible, Newtonian blood flow (ρ = 1060 kg/m3; μ = 0.00371 Pa.s) and rigid, impermeable walls were assumed. The pressure field upstream of the pump was modeled using a validated in-house artificial compressibility computational fluid dynamics solver used extensively in previous studies for in silico cardiovascular flow assessment. A constant AAo inflow was modeled at the aortic root (Reynolds number, Re = 1000), and coronary outlet flow splits were prescribed to ensure normal coronary perfusion of 3% (∼163.28 ml/min) of cardiac output (CO = 5.44 l/min). The running average flow field was analyzed after 1 second of unsteady flow. The flow downstream of the pump was assessed in a second set of steady-state simulations conducted in ansys fluent 14.0 (ANSYS Inc., Cannonsburg, PA). Simulative of a pump outlet, an inlet mass flow rate was specified with local rotational components at the downstream model inlet. Swirling effects of increasing intensity were modeled by specifying the percentage tangential component (0%, 20%, and 40%) of inflow, where no swirling inlet component was an approximation of off-pump aortic flow. Aortic outlets were numerically modeled by defining constant resistance boundary conditions tuned in a manner such that a 40%–60% mass flow split between head-neck vessels and descending aorta (DAo) was maintained.In the upstream model, in order to maintain coronary flow at 3% of CO, during steady AAo outflow, a remarkably low pressure gradient (&lt;0.25 mm Hg) was found necessary to be maintained across the aortic root (Fig. 1(b)). Increased swirling component (from 0% to 40%) modeled at the outlet of the pump resulted in decreased mass flow in the brachiocephalic artery (BCA) (from 1.78 to 1.62 l/min, p &lt; 0.001) with a corresponding increase flow to the DAo (from 3.33 to 3.54 l/min, p &lt; 0.001), owing to the Venturi effect created by virtue of the swirling flow at the base of the BCA. Mass flow rate in the left common carotid and left subclavian artery did not show significant variation with inlet swirling component changes. The mean wall shear stress in the transverse aortic arch was observed to increase and became more uniform as the swirling component was increased (Fig. 1(c)), which was congruent with the noted increases in the DAo flow split.An AAo blood pump is promising in regard to its potential transcatheter deployment. Swirling/helical flow patterns from the axial aortic pumps bear closer resemblance to physiological flows in a normal aortic arch. Device anchoring in the AAo that, by design, facilitates annular reverse flow between pump and AAo walls could potentially avert issues relating to improper coronary perfusion. New boundary condition implementations facilitating more realistic modeling of the suction effects of the AAo pump is a subject of ongoing efforts.