Contrast CT Images Research Articles

Coverage‐based treatment planning to accommodate delineation uncertainties in prostate cancer treatment

To compare two coverage-based planning (CP) techniques with fixed margin-based (FM) planning for high-risk prostate cancer treatments, with the exclusive consideration of the dosimetric impact of delineation uncertainties of target structures and normal tissues. In this work, 19-patient data sets were involved. To estimate structure dose for each delineated contour under the influence of interobserver contour variability and CT image quality limitations, 1000 alternative structures were simulated by an average-surface-of-standard-deviation model, which utilized the patient-specific information of delineated structure and CT image contrast. An IMRT plan with zero planning-target-volume (PTV) margin on the delineated prostate and seminal vesicles [clinical-target-volume (CTV prostate) and CTVSV] was created and dose degradation due to contour variability was quantified by the dosimetric consequences of 1000 alternative structures. When D98 failed to achieve a 95% coverage probability objective D98,95 ≥ 78 Gy (CTV prostate) or D98,95 ≥ 66 Gy (CTVSV), replanning was performed using three planning techniques: (1) FM (PTV prostate margin = 4,5,6 mm and PTVSV margin = 4,5,7 mm for RL, PA, and SI directions, respectively), (2) CPOM which optimized uniform PTV margins for CTV prostate and CTVSV to meet the D98,95 objectives, and (3) CPCOP which directly optimized coverage-based objectives for all the structures. These plans were intercompared by computing percentile dose-volume histograms and tumor-control probability/normal tissue complication probability (TCP/NTCP) distributions. Inherent contour variability resulted in unacceptable CTV coverage for the zero-PTV-margin plans for all patients. For plans designed to accommodate contour variability, 18/19 CP plans were most favored by achieving desirable D98,95 and TCP/NTCP values. The average improvement of probability of complication free control was 9.3% for CPCOP plans and 3.4% for CPOM plans. When the delineation uncertainties need to be considered for prostate patients, CP techniques can produce more desirable plans than FM plans for most patients. The relative advantages between CPCOP and CPOM techniques are patient specific.

SU‐D‐207‐06: Clinical Validations of Shading Correction for Cone‐Beam CT Using Planning CT as a Prior

Purpose:Current cone‐beam CT (CBCT) images contain severe shading artifacts mainly due to scatter, hindering their quantitative use in current radiation therapy. We have previously proposed an effective shading correction method for CBCT using planning CT (pCT) as prior knowledge. In this work, we investigate the method robustness via statistical analyses on studies of a large patient group and compare the performance with that of a state‐of‐the‐art method implemented on the current commercial radiation therapy machine ‐‐ the Varian Truebeam system.Methods:Since radiotherapy patients routinely undergo multiple‐detector CT (MDCT) scans in the planning procedure, we use the high‐quality pCT as “free” prior knowledge for CBCT image improvement. The CBCT image with no correction is first spatially registered with the pCT. Primary CBCT projections are estimated via forward projections of the registered image. The low frequency errors in the projections, which stem from mainly scatter, are estimated by filtering the difference between original line integral and the estimated scatter projections. The corrected CBCT image is then reconstructed from the scatter corrected projections. The proposed method is evaluated on 40 cancer patients.Results:On all patient images, we compare errors on CT number, spatial non‐uniformity (SNU) and image contrast, using pCT as the ground truth. T‐tests show that our algorithm improves over the Varian method on CBCT accuracies of CT number and SNU with 90% confident. The average CT number error is reduced from 54.8 HU on the Varian method to 40.9 HU, and the SNU error is reduced from 7.7% to 3.8%. There is no obvious improvement on image contrast.Conclusion:Large‐group patient studies show that the proposed pCT‐based algorithm outperforms the Varian method of the Truebeam system on CBCT shading correction, by providing CBCT images with higher CT number accuracy and greater image uniformity.

Abstract 19973: Dynamic Thallium-201 SPECT/CT Provides Quantitative Index of Myocardial Flow and Viability: Validation in Porcine Post-Myocardial Infarction Model

Introduction: Thallium-201 (Tl-201) SPECT imaging is routinely used to evaluate relative myocardial perfusion and/or viability. In this study, we have evaluated Tl-201 kinetics in a porcine model of myocardial infarction (MI) with dynamic imaging on a hybrid SPECT/CT system. Methods: Tl-201 SPECT and contrast CT imaging were performed on hybrid SPECT/64-slice CT (GE Discovery NM/CT 570c) in Yorkshire pigs (n=5) one week following a 90 min balloon occlusion of the LAD below the first diagonal branch. Tl-201 (83-158 MBq) was injected after the initiation of a 900s list-mode acquisition. The list-mode data was reconstructed with MLEM using 30 iterations creating 23 frames (12 x 10s; 6 x 30s; 5 x 120s). Reconstructed dynamic SPECT data was analyzed using FlowquantTM semi-automated analysis software with a 1-compartment model. K1 (index of flow) and k2 (index of viability) were assessed within a 17-segment model of the left ventricle. Four segments within the central infarcted LAD territory were compared to six segments of the contralateral inferolateral wall. The same segments were analyzed for wall thickening from ECG-gated contrast CT scans using centerline approach (GE AW Cardiac Function Xpress). Results: K1 was significantly decreased in the MI vs contralateral normal regions (0.52 ± 0.17 vs 0.61 ± 0.16 ml/min/g, p<0.02). K2 an index of tissue viability was significantly increased in the MI region (0.42 ± 0.19 vs 0.32 ± 0.12 /min, p<0.04), reflecting accelerated Tl-201 washout in MI. Wall thickening in the same MI region was significantly decreased (0.33 ± 1.5 mm vs 3.3 ± 1.9 mm, p<0.005). Conclusions: Dynamic Tl-201 SPECT/CT imaging provides a quantitative index of both myocardial flow and viability using a 1-compartment model. This preliminary pre-clinical demonstrates the potential for dynamic Tl-201 SPECT imaging to quantify myocardial viability early post-MI.

Reninoma: an uncommon cause of Renin-mediated hypertension.

Reninoma (juxtaglomerular cell tumor) is a rare cause of renin-mediated hypertension. Reninomas are usually diagnosed in adolescents and young adults with occasional reports in younger children. Patients typically present with a long history of headaches leading to a diagnosis of severe hypertension that responds well to antihypertensive treatment targeting the renin-angiotensin-aldosterone system. The clue to clinical diagnosis is the presence of hypokalemia and metabolic alkalosis on the first blood sample drawn before any treatment is instituted. Elevated blood levels of renin and aldosterone confirm the clinical suspicion of renin-mediated hypertension. Diagnostic imaging is employed to identify the source of excessive renin production. While renal ultrasound can miss reninoma, contrast CT or magnetic resonance imaging of the kidneys are diagnostic modalities of choice leading to the correct diagnosis. Renal vein renin sampling with lateralization might help to identify the site of excessive renin production. Nephron-sparing surgery is curative with maintenance of normal blood pressure after discontinuation of antihypertensive medications in the majority of patients. In this paper, we present the case of reninoma in an adolescent girl emphasizing clinical presentation, diagnostic evaluation, and medical and surgical treatment of this rare tumor. We also discuss important points in the management of children presenting with renin-mediated hypertension.

SU‐E‐I‐58: Detecting Tumors with Extremely Low Contrast in CT Images

Purpose:Tumors such as the prostate focal lesions and the brain metastases have extremely low CT contrast and MRI is usually used for target delineation. The target contours are propagated to the CT for treatment planning and patient positioning. We have employed an advanced denoising method eliminating the noise and allow magnification of subtle contrast of these focal lesions on CT.Methods:Five prostate and two brain metastasis patients with MRI T2, diffusion or dynamic contrast enhanced (DCE) images confirmed focal lesions were included. One brain patients had 5 metastases. A block matching 3D (BM3D) algorithm was adapted to reduce the noise of kVCT images used for treatment planning. The gray‐level range of the resultant images was narrowed to magnify the tumor‐normal tissue contrast.Results:For the prostate patients, denoised kVCT images showed focal regions at 5, 8,11‐1, 2, and 8–10 oclock for the 5 patients, this is highly consistent to the radiologist confirmed focal lesions based on MRI at 5, 7, 11‐1, 2 and 8–10 oclock in the axial plane. These CT focal regions matched well with the MRI focal lesions in the cranio‐caudal position. The average increase in density compared to background prostate glands was 0.86%, which corresponds to ∼50% increase in cellularity and is lower than the average CT noise level of 2.4%. For the brain patients, denoised kVCT showed 5/6 metastases. The high CT‐density region of a metastasis is 2‐mm off from its corresponding elevated MRI perfusion center. Overall the detecting sensitivity was 91%.Conclusion:It has been preliminarily demonstrated that the higher tumor cellularity can be detected using kVCT. The low contrast‐to‐noise information requires advanced denoising to reveal. The finding is significant to radiotherapy by providing an additional tool to locate focal lesions for confirming MRI‐CT registration and providing a highly accessible outcome assessment tool.

Correction algorithm for environmental scattering in industrial computed tomography

Scattering of X-ray photons in the environment causes artefacts in high-energy X-ray computed tomography (CT). Here, an analytical correction formula applied to transmission images is presented and experimentally validated on data from a 450kV cone-beam CT-system. This method increases the contrast of CT-images from a large aluminium step cylinder by a factor exceeding 2.5. For complex objects, the procedure reduces the variance of the attenuation values for the material given an optimal correction parameter. For the considered source parameters, this correction parameter could be derived from the measurement data by a simple procedure with a correlation coefficient of 0.996±0.005.

Phase contrast imaging X-ray computed tomography: Quantitative characterization of human patellar cartilage matrix with topological and geometrical features.

Current assessment of cartilage is primarily based on identification of indirect markers such as joint space narrowing and increased subchondral bone density on x-ray images. In this context, phase contrast CT imaging (PCI-CT) has recently emerged as a novel imaging technique that allows a direct examination of chondrocyte patterns and their correlation to osteoarthritis through visualization of cartilage soft tissue. This study investigates the use of topological and geometrical approaches for characterizing chondrocyte patterns in the radial zone of the knee cartilage matrix in the presence and absence of osteoarthritic damage. For this purpose, topological features derived from Minkowski Functionals and geometric features derived from the Scaling Index Method (SIM) were extracted from 842 regions of interest (ROI) annotated on PCI-CT images of healthy and osteoarthritic specimens of human patellar cartilage. The extracted features were then used in a machine learning task involving support vector regression to classify ROIs as healthy or osteoarthritic. Classification performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The best classification performance was observed with high-dimensional geometrical feature vectors derived from SIM (0.95 ± 0.06) which outperformed all Minkowski Functionals (p < 0.001). These results suggest that such quantitative analysis of chondrocyte patterns in human patellar cartilage matrix involving SIM-derived geometrical features can distinguish between healthy and osteoarthritic tissue with high accuracy.

Correlation of serum apelin level with coronary calcium score in patients with suspected coronary artery disease

Introduction A growing body of evidence indicates that apelin, a relatively recent member of the adipokines family, has a potential anti-atherogenic effect. An association between low serum apelin state and coronary artery disease (CAD) was previously reported; however, the relationship between apelin and the atherosclerotic burden was unclear. Objectives Our aim was to explore the correlation of serum apelin level with coronary calcium score (CCS) as a quantitative marker of coronary atherosclerosis. Methods This observational cross-sectional study enrolled 100 consecutive subjects referred for cardiac multi-detector computed tomography (MDCT) for assessment of CAD (mean age 54 ± 9.7 years, 51 male and 49 females). Clinical parameters, glycemic and lipid profile, high sensitivity CRP (hsCRP), homeostasis model assessment of insulin resistance (HOMA-IR), serum creatinine and complete blood count were assessed. Serum apelin levels were determined using a commercially available Enzyme Immunoassay (EIA) Kit. High resolution non contrast CT images were acquired by a 64-raw MDCT and CCS was calculated using the Agatston scoring method. Results Forty three percent of the studied subjects had positive coronary artery calcification (CAC). The mean CCS was 79 ± 196.5 Agatston units. Subjects with detectable CAC had significantly higher fasting plasma glucose, HbA1c and WBCs count than subjects without detectable CAC (p 0.05). Most importantly, subjects with detectable CAC had significantly lower serum apelin level than subjects without CAC (1.3 ± 0.4 ng/ml vs. 2.8 ± 0.6 ng/ml, p 0.001). In addition, there was a statistically significant inverse correlation between serum apelin levels and CCS (r = 0.591, p 0.001); on multivariate analysis this correlation was found to be independent of traditional cardiovascular risk factors and hs-CRP. Conclusion To the best of our knowledge, this is the first report of an independent association between apelin and CCS in patients with suspected CAD. Apelin emerges as a possible novel biomarker for CAD, but this result remains to be proved prospectively.

Isoniazid Hepatotoxicity Requiring Liver Transplantation

A 65-year-old female Peruvian immigrant was initially evaluated for potential initiation of anti-tumor necrosis factor (TNF)-a therapy for her poorly controlled rheumatoid arthritis. The patient had a history of thyroid cancer that had required thyroidectomy and replacement levothyroxine. The patient’s quantiferon test was positive, and she also had a history of aspartate transaminase (AST) and alanine transaminase (ALT) values between 40 and 60 IU/ L for at least the previous 4 years. Previous laboratory evaluation had revealed a positive anti-nuclear antibody (ANA) titer at dilution of 1:640 with homogeneous pattern, positive anti-smooth muscle antibody, and elevated immunoglobulin G (IgG) levels at 2,310 mg/dL. The patient, however, denied any prior history of chronic liver disease; consequently, no further evaluation was pursued. Isoniazid (INH) prophylaxis for latent tuberculosis infection (LTBI), was instituted for an expected nine-month course. The patient did not take any dietary or herbal supplements and did not drink alcohol. One month after initiating INH, the patient sought evaluation for jaundice, nausea, and fatigue. Her total bilirubin level was 11.3 mg/ dL, direct bilirubin level 8.6 mg/dL, AST 1,642 IU/L, ALT 1,576 IU/L, alkaline phosphatase 246 IU/L, albumin 3.0 g/ dL, and international normalized ratio 1.2. Serologic testing for acute viral hepatitis was negative. Because of presumed INH hepatotoxicity, INH was discontinued. Two weeks later, the patient complained of worsening nausea as well as new-onset ascites and lower extremity edema. Her total bilirubin was 27.8 mg/dL, direct bilirubin 21.6 mg/ dL, AST 726 IU/L, ALT 588 IU/L, alkaline phosphatase 254 IU/L, albumin 2.4 g/dL, and international normalized ratio 1.8. Triphasic contrast CT imaging demonstrated a shrunken and nodular liver and moderate-volume ascites. The patient was treated with spironolactone, furosemide, and subcutaneous vitamin K, but continued to feel poorly. Two weeks later, she developed encephalopathy with worsening renal insufficiency and international normalized ratio rising to 2.3. She was transferred to Stanford Hospital for urgent liver transplant evaluation. Upon transfer, WBC was 14.2 K/lL, platelet count 112 K/lL, sodium level 126 mmol/L, potassium level 5.4 mmol/L, CO2 18 mmol/L, BUN 57 mg/dL, creatinine 2.9 mg/dL, AST 229 IU/L, ALT 251 IU/L, total bilirubin 26.1 mg/dL, alkaline phosphatase 502 IU/L, albumin 1.4 g/dL, and international normalized ratio 2.6. The patient’s model for end-stage liver disease (MELD) score was 40. Expedited transplant evaluation was initiated, and supportive care was provided with lactulose, rifaximin, and intravenous albumin. The patient also received intravenous vitamin K as well as fresh frozen plasma transfusions. Despite these measures, the patient experienced worsening encephalopathy, azotemia, and hepatic synthetic dysfunction. On E. Sheen (&) M. H. Nguyen Division of Gastroenterology and Hepatology, Department of Medicine, School of Medicine, Stanford University, Alway Building, Room M-211, 300 Pasteur Drive, Stanford, CA 94305, USA e-mail: esheen@stanford.edu

Successful Excision of a Suspected Mycotic Transplant Renal Artery Patch Aneurysm With Renal Allograft Autotransplantation

Successful Excision of a Suspected Mycotic Transplant Renal Artery Patch Aneurysm With Renal Allograft Autotransplantation

In vivo near-infrared photothermal therapy and computed tomography imaging of cancer cells using novel tungsten-based theranostic probe.

Photothermal therapy, as a physical therapeutic technique to kill cancer, has generated a great deal of interest. Photothermal agents hence play a critical role in this modern therapy. We report the use of transition metal oxides as photothermal agents based on PEGylated WO3-x nanoparticles. The well-prepared nanoparticles presented effective results during photothermal therapy both in vitro and in vivo by using near-IR laser irradiation (980 nm, 0.5 W cm(-2)). The tumor cells were effectively damaged using low power density during a short irradiation time without destroying healthy tissues. In vitro results of photothermal therapy with PEGylated WO3-x nanoparticles proved to be effective on 4T1 murine breast cancer cells via a confocal microscopy method and MTT assay. In vivo results were further confirmed by hematoxylin and eosin (H & E) histological staining. Additionally, PEGylated WO3-x nanoparticles were shown to be effective as a CT imaging contrast agent on a tumor-bearing mouse model. Our results suggest that this generation of PEGylated WO3-x nanoparticles can potentially be used in oncological CT imaging and photothermal therapy.

X-ray phase-contrast CT imaging of the acupoints based on synchrotron radiation

In this paper, the morphology of the acupuncture point (abbreviated as acupoint hereafter) or tissue where there were no acupoints in the fractional rabbit hind limb was studied by in-line phase contrast CT imaging (PCI-CT) methods based on synchrotron radiation. The density of micro-vessels was calculated for tissues with acupoints or without acupoints. Differences between acupoints area and non-acupoint areas determined by the density of the micro-vessels propose a strong evidence of the existence of acupoints. Our results showed that there were two significantly higher densities of the micro-vessels, where two acupoints were located, respectively. In addition, there were large numbers of involutedly microvascular structure in the acupoint areas. Nevertheless, in non-acupoints area, the microvascular structure was relatively simple and flat.

A Rare Case of Concurrent SMA Syndrome and Portal Vein Thrombosis

Purpose: This is a case of a 62-year-old man who presented with complaints of periumbilical abdominal pain and vomiting of 2 days' duration. He noted a 4-month history of watery, non-mucoid diarrhea with a 15lb unintentional weight loss. Prior workup for chronic diarrhea included stool studies, colonoscopy, and CT scan abdomen, all of which were normal. The patient appeared cachectic with a diffusely tender abdomen and voluntary guarding. Initial labwork was pertinent only a mild leukocytosis. Liver function tests, amylase, lipase, and lactate levels were all normal. A CT scan abdomen revealed changes consistent with portal vein thrombosis and SMA syndrome (Figures 1 and 2). An abdominal ultrasound was obtained, revealing changes confirming SMA syndrome. An EGD revealed a dilated stomach with large amounts of gastric contents. A decompressive gastrostomy tube with a feeding jejunal extension was placed radiographically. The patient was started on heparin and broad-spectrum antibiotics. The patient was managed medically with improvement in his clinical status. He was discharged to a rehabilitation facility in stable condition. This case highlights the effects of SMA syndrome on the portal vasculature. Review of the literature reveals a paucity of similar cases, most involving the pediatric population with SMA syndrome, complicated by gastric wall pneumatosis and portal venous gas. In our case, local compression on the SMV well may very well have been the single most important contributing factor. Special attention should also be paid to pressure effects of a dilated proximal duodenum and/or dilated stomach. We should remain alert to the possible association of SMA syndrome with the portal vasculature and rule it out on imaging.Figure 1: Axial contrast CT image obtained during the portal venous phase demonstrates a non-occlusive thrombus within the right portal vein (arrow).Figure 2: Image demonstrates narrowing of the distance between the SMA (arrow) and the aorta (A) at the level of the 3rd portion of the duodenum (arrowhead).

Multi-staged robotic stereotactic radiosurgery for large cerebral arteriovenous malformations

To investigate a multi-staged robotic stereotactic radiosurgery (SRS) delivery technique for the treatment of large cerebral arteriovenous malformations (AVMs). The treatment planning process and strategies to optimize both individual and composite dosimetry are discussed. Eleven patients with large (30.7 ± 19.2 cm(3)) AVMs were selected for this study. A fiducial system was designed for fusion of targets between planar angiograms and simulation CT scans. AVMs were contoured based on single contrast CT, MRI and orthogonal angiogram images. AVMs were divided into 3-8 sub-target volumes (3-7 cm(3)) for sequential treatment at 1-4 week intervals to a prescription dose of 16-20 Gy. Forward and inversely developed treatment plans were optimized for 95% coverage of the total AVM volume by dose summation from each sub-volume, while minimizing dose to surrounding tissues. Dose-volume analysis was used to evaluate the PTV coverage, dose conformality (CI), and R50 and V12 Gy parameters. The treatment workflow was commissioned and able to localize within 1mm. Inverse optimization outperformed forward planning for most patients for each index considered. Dose conformality was shown comparable to staged Gamma Knife treatments. The CyberKnife system is shown to be a practical delivery platform for multi-staged treatments of large AVMs using forward or inverse planning techniques.

8:16 AM Abstract No. 187 - ■ Dr. Constantin Cope Medical Student Research Award Alginate microspheres with magnetically triggered gemcitabine release

Purpose Alginate microspheres could serve as an ideal drug delivery platform for selective transcatheter administration of gemcitabine to pancreatic tumors. This study aimed to modify gemcitabine release with ultrasmall superparamagnetic iron oxide (USPIO) clusters. We tested the hypothesis that USPIOs will adsorb drug and slow drug release. Further, we hypothesized that drug release can be accelerated by magnetic induction heating. Lastly, we investigated the CT and MR imaging properties of these microspheres loaded with USPIOs and barium salts. Materials and Methods Alginate microspheres were synthesized by gelation of alginate, calcium salts, USPIOs, and hydroxypropyl cellulose using microfluidic channels. USPIOs were prepared by chemical reduction of iron (III) chloride. Gemcitabine was added by diffusion in drug solution. Drug release studies were performed in triplicate by dialyzing microspheres and quantifying drug release via absorption spectroscopy. Heat triggered drug release studies were performed with an Ambrell EasyHeat producing oscillating magnetic fields (1.85 kW, 200 kHz). Imaging of microspheres was performed with Bruker 7T MRI and Somatom Sensation Cardiac 64 CT. Results At physiological conditions, the presence of USPIOs in alginate microspheres slowed the rate of drug release by an average of 25% compared with drug release from microspheres without USPIOs. Magnetic induction heating accelerated drug release by an average of 18% compared with control. Microspheres were imaged with CT and MRI demonstrating image contrast well correlated with barium and USPIO content. Conclusion USPIOs can slow the rate of gemcitabine release and induction heating can trigger an acceleration of drug release from these USPIO containing alginate microspheres. These microspheres provide image contrast for visualization with both CT and MRI modalities. Future animal model studies will evaluate the efficacy of these microspheres for selective transcatheter delivery of gemcitabine to pancreatic tumors.

Assessment of a novel compressed sensing algorithm for reconstructing phase contrast CT images of the canine prostate

Phase contrast computed tomography (PC CT) represents a generational advance in medical and anatomical imaging with greatly improved spatial and soft tissue contrast resolution. Achieving good image quality with PC CT can require up to 4000 image projections leading to a high radiation dose and long image acquisition time. New image reconstruction methods would greatly reduce the number of projections without substantially sacrificing image quality. In sparse‐view imaging, strong streak artifacts may appear in conventionally reconstructed images, compromising image quality. Compressed sensing algorithm has shown potential to accurately recover images from highly incomplete data. The main feature of our algorithm is the use of two sparsity transforms: discrete wavelet transform and discrete gradient transform, both of which are proven to be powerful sparsity transforms. We reconstructed canine prostate images with filtered back projection and our compressed sensing algorithm using 50, 100, 120, 150, and 180 projections. Our results demonstrate that our proposed method can produce satisfactory images from only 150 projections. Research funding was provided by the Saskatchewan Health Research Fund.

Esophagus Segmentation from 3D CT Data Using Skeleton Prior-Based Graph Cut

The segmentation of organs at risk in CT volumes is a prerequisite for radiotherapy treatment planning. In this paper, we focus on esophagus segmentation, a challenging application since the wall of the esophagus, made of muscle tissue, has very low contrast in CT images. We propose in this paper an original method to segment in thoracic CT scans the 3D esophagus using a skeleton-shape model to guide the segmentation. Our method is composed of two steps: a 3D segmentation by graph cut with skeleton prior, followed by a 2D propagation. Our method yields encouraging results over 6 patients.

Image guidance in trans-sphenoidal surgery for giant pituitary adenomas: Luxury or necessity?

Abstract In spite of availability of image guidance (neuronavigation) at major centers around the world, most trans-sphenoidal surgeries for pituitary adenomas continue to be done under fluoroscopic control. On the other hand, the high mortality and morbidity for giant pituitary adenomas is mainly due to inadequate tumor removal. The objective of this study was to study to utility of image guidance in trans-sphenoidal surgeries for optimizing tumor removal in giant pituitary adenomas. This was a prospective study carried out over a two years (January 2009-December 2010) in the Department of Neurosurgery, All India Institute of Medical Sciences. Patients with giant pituitary adenomas who underwent trans-sphenoidal surgery by the author were included. All surgeries were done under image-guidance only and no fluoroscopy was employed. Trajectory was defined using the image guidance and bone work done accordingly to optimize tumor removal. All patients had a contrast CT of the head done within 48 h of surgery to see for residual tumor. Sixteen patients with pituitary adenomas were operated using only image-guidance in the study period. Twelve patients had virgin tumors and four patients had recurrent/residual tumors. In four patients, noncontrast MR images were used in for image guidance and contrast CT images were used in the rest. The mean set up time for image-guidance was 11 min (range 7–15 min). The mean “overall accuracy of registration” was 1.6 mm (range 1.4–2.1 mm). The mean operating time was 72 min (range 52–96 min). In all cases, midline and the relation of the carotid artery to the sella could be confirmed using the image-guidance. There were no intraoperative complications. Postoperative scans showed residual tumor in nine patients. The residual tumor was &lt;10% in four patients, &lt;25% in four patients and &gt;25% in one patient (with a fibrous recurrent/residual tumor). Image guidance markedly improves the visualization of sellar floor and its relation to the carotid arteries, thereby improving the safety and quality of the surgical procedure, besides being free of limitations of fluoroscopy. More importantly the trajectory can be defined for optimizing tumor removal in such patients. Image-guidance can easily replace flouroscopy for trans-sphenoidal surgeries and when available should be the first choice when operating pituitary tumors trans-sphenoidally.

Sequential combination treatment (arterial embolization and percutaneous radiofrequency ablation) of inoperable renal cell carcinoma: single-center pilot study

Potential drawbacks of percutaneous radiofrequency ablation (RFA) for renal cell carcinoma (RCC) include local recurrence after RFA due to a limited ablation area, massive hemorrhage induced by kidney puncture, and difficulty in visualizing the tumor at CT-guided puncture. To evaluate retrospectively the technical success, effectiveness, and complications elicited in patients with unresectable RCC following single-session sequential combination treatment consisting of renal arterial embolization followed by RFA. Ten patients (12 RCCs) who were not candidates for surgery were included in this pilot study. All tumors ranged from 18-66 mm in size (mean 31 ± 3.9 mm), and were percutaneously ablated several hours after embolization of the tumor vessels with iodized oil and gelatin sponges. We evaluated the technical success, effectiveness, effect on renal function, and complications of this treatment. Effectiveness was judged on CT and/or MR images obtained every three months after RFA. The effect on renal function was assessed based on the creatinine level and glomerular filtration rate (GFR) before, one week, and three months after the procedure. Renal arterial embolization followed by percutaneous RFA was technically successful in all patients. On contrast CT and/or MR images obtained one week and three months after RFA we observed necrosis in the embolized segment of all RCCs. There were no major complications during and after the procedure. All patients reported tolerable pain and a burning sensation during RFA. After the procedure, five patients (50%) experienced back pain, one each manifested fluid collection, subcapsular hematomas, hematuria, or nausea. There were no instances of recurrence during a mean follow-up period of 47 ± 3.8 months. We noted no significant difference in serum creatinine and GFR before and after treatment. Our pilot study suggests that sequential combination treatment by renal arterial embolization followed by percutaneous RFA is feasible in patients with inoperable RCC. The treatment complications were acceptable and excellent effects were obtained.

Anti-VEGFR2-conjugated PLGA microspheres as an x-ray phase contrast agent for assessing the VEGFR2 expression

The primary goal of this study was to evaluate the feasibility of using anti-vascular endothelial growth factor receptor 2 (VEGFR2)-conjugated poly(lactic-co-glycolic acid) (PLGA) microspheres as an x-ray phase contrast agent to assess the VEGFR2 expression in cell cultures. The cell lines, mouse LLC (Lewis lung carcinoma) and HUVEC (human umbilical vein endothelial cell), were selected for cell adhesion studies. The bound PLGA microspheres were found to better adhere to LLC cells or HUVECs than unbound ones. Absorption and phase contrast images of PLGA microspheres were acquired and compared in vitro. Phase contrast imaging (PCI) greatly improves the detection of the microspheres as compared to absorption contrast imaging. The cells incubated with PLGA microspheres were imaged by PCI, which provided clear 3D visualization of the beads, indicating the feasibility of using PLGA microspheres as a contrast agent for phase contrast CT. In addition, the microspheres could be clearly distinguished from the wall of the vessel on phase contrast CT images. Therefore, the approach holds promise for assessing the VEGFR2 expression on endothelial cells of tumor-associated vessels. We conclude that PLGA microsphere-based PCI of the VEGFR2 expression might be a novel, promising biomarker for future studies of tumor angiogenesis.