Rajiv Gupta

Publications

• 2.78

  Impact points

  Computational high-resolution heart phantoms for medical imaging and dosimetry simulations.

  Songxiang Gu, Rajiv Gupta, Iacovos Kyprianou

  Physics in medicine and biology. 08/2011; 56(18):5845-64.

  Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive the... [more] Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive therapies for CAD such as angioplasty and stenting are rendered under fluoroscopic guidance. Both invasive and non-invasive imaging modalities employ ionizing radiation and there is concern for deterministic and stochastic effects of radiation. Accurate simulation to optimize image quality with minimal radiation dose requires detailed, gender-specific anthropomorphic phantoms with anatomically correct heart and associated vasculature. Such phantoms are currently unavailable. This paper describes an open source heart phantom development platform based on a graphical user interface. Using this platform, we have developed seven high-resolution cardiac/coronary artery phantoms for imaging and dosimetry from seven high-quality CTA datasets. To extract a phantom from a coronary CTA, the relationship between the intensity distribution of the myocardium, the ventricles and the coronary arteries is identified via histogram analysis of the CTA images. By further refining the segmentation using anatomy-specific criteria such as vesselness, connectivity criteria required by the coronary tree and image operations such as active contours, we are able to capture excellent detail within our phantoms. For example, in one of the female heart phantoms, as many as 100 coronary artery branches could be identified. Triangular meshes are fitted to segmented high-resolution CTA data. We have also developed a visualization tool for adding stenotic lesions to the coronaries. The male and female heart phantoms generated so far have been cross-registered and entered in the mesh-based Virtual Family of phantoms with matched age/gender information. Any phantom in this family, along with user-defined stenoses, can be used to obtain clinically realistic projection images with the Monte Carlo code penMesh for optimizing imaging and dosimetry.

  Download
• 3.30

  Impact points

  Temporal resolution of dynamic angiography using flat panel volume CT: in vivo evaluation of time-dependent vascular pathologies.

  R Gupta, A Mehndiratta, A P Mitha, M Grasruck, C Leidecker, C Ogilvy, T J Brady

  AJNR. American journal of neuroradiology. 08/2011; 32(9):1688-96.

  Recently introduced fpVCT scanners can capture volumetric (4D) time-varying projections enabling whole-organ dynamic CTA imaging. The main objective of this study was to assess the temporal resolution of dynamic CTA in discriminating various phases of rapid and slow time-dependent neurovascular path... [more] Recently introduced fpVCT scanners can capture volumetric (4D) time-varying projections enabling whole-organ dynamic CTA imaging. The main objective of this study was to assess the temporal resolution of dynamic CTA in discriminating various phases of rapid and slow time-dependent neurovascular pathologies in animal models. Animal models were created to assess phasic blood flow, subclavian steal phenomena, saccular aneurysms, and neuroperfusion under protocols approved by the SRAC. Animals with progressively increasing heart rate-Macaca sylvanus (~100 bpm), Oryctolagus cuniculus (NZW rabbit) (~150 bpm), Rattus norvegicus (~300 bpm), Mus musculus (~500 bpm)-were imaged to challenge the temporal resolution of the system. FpVCT, a research prototype with a 25 × 25 × 18 cm coverage, was used for dynamic imaging with the gantry rotation time varying from 3 to 5 seconds. Volumetric datasets with 50% temporal overlap were reconstructed; 4D datasets were analyzed by using the Leonardo workstation. Dynamic imaging by using fpVCT was capable of demonstrating the following phenomena: 1) subclavian steal in rabbits (ΔT ≅ 3-4 seconds); 2) arterial, parenchymal, and venous phases of blood flow in mice (ΔT ≅ 2 seconds), rabbits (ΔT ≅ 3-4 seconds), and Macaca sylvanus (ΔT ≅ 3-4 seconds); 3) sequential enhancement of the right and left side of the heart in Macaca sylvanus and white rabbits (ΔT ≅ 2 seconds); and 4) different times of the peak opacification of cervical and intracranial arteries, venous sinuses, and the jugular veins in these animals (smallest, ΔT ≅ 1.5-2 seconds). The perfusion imaging in all animals tested was limited due to the fast transit time through the brain and the low contrast resolution of fpVCT. Dynamic imaging by using fpVCT can distinguish temporal processes separated by >1.5 seconds. Neurovascular pathologies with a time constant >1.5 seconds can be evaluated noninvasively by using fpVCT.
• 1.57

  Impact points

  Trabecular structure analysis using C-arm CT: comparison with MDCT and flat-panel volume CT.

  Catherine M Phan, Eric A Macklin, Miriam A Bredella, Monica Dadrich, Paul Flechsig, Albert J Yoo, Joshua A Hirsch, Rajiv Gupta

  Skeletal radiology. 08/2011; 40(8):1065-72.

  This paper assesses interscan, interreader, and intrareader variability of C-arm CT and compares it to that of flat-panel volume-CT (fpVCT) and high-definition multi-detector-CT (HD-MDCT). Five cadaver knee specimens were imaged using C-arm-CT, fpVCT, and HD-MDCT. Apparent (app.) trabecular bone vol... [more] This paper assesses interscan, interreader, and intrareader variability of C-arm CT and compares it to that of flat-panel volume-CT (fpVCT) and high-definition multi-detector-CT (HD-MDCT). Five cadaver knee specimens were imaged using C-arm-CT, fpVCT, and HD-MDCT. Apparent (app.) trabecular bone volume fraction (BV/TV), app. trabecular number (TbN), app. trabecular spacing (TbSp), and app. trabecular thickness (TbTh) of the proximal tibia were measured by three readers. Interreader, intrareader, and interscan variability for C-arm CT was expressed as coefficient of variation (CV), standard deviation (SD), and intraclass correlation coefficient (ICC). With the exception of app.TbSp (CV: 7.05-9.35%, SD: 0.06-0.09, ICC: 0.89-0.94), the variability of C-arm CT was low (CV: 2.41-6.43%, SD: 0.01-0.048, ICC: 0.65-0.98). Its interreader reliability (CV: 2.66-4.55%, SD: 0.01-0.03, ICC: 0.81-0.95) was comparable to that of HD-MDCT (CV: 2.41-4.08%, SD: 0.014-0.016, ICC: 0.95-0.96), and fpVCT (CV: 3.13-5.63%, SD: 0.009-0.036, ICC: 0.64-0.98) for all parameters except app.TbSp. C-arm CT is a reliable method for assessing trabecular bone architectural parameters with the exception of app.TbSp due to spatial resolution limitation.
• 47.05

  Impact points

  Case records of the Massachusetts General Hospital. Case 14-2011. A woman with asymmetric sensory loss and paresthesias.

  David A Chad, John H Stone, Rajiv Gupta

  The New England journal of medicine. 05/2011; 364(19):1856-65.
• 3.58

  Impact points

  Usefulness of comprehensive cardiothoracic computed tomography in the evaluation of acute undifferentiated chest discomfort in the emergency department (CAPTURE).

  Ian S Rogers, Dahlia Banerji, Emily L Siegel, Quynh A Truong, Brian B Ghoshhajra, Thomas Irlbeck, Suhny Abbara, Rajiv Gupta, Ricardo J Benenstein, Garry Choy, Laura L Avery, Robert A Novelline, Fabian Bamberg, Thomas J Brady, John T Nagurney, Udo Hoffmann

  The American journal of cardiology. 03/2011; 107(5):643-50.

  Newer cardiac computed tomographic (CT) technology has permitted comprehensive cardiothoracic evaluations for coronary artery disease, pulmonary embolism, and aortic dissection within a single breath hold, independent of the heart rate. We conducted a randomized diagnostic trial to compare the effic... [more] Newer cardiac computed tomographic (CT) technology has permitted comprehensive cardiothoracic evaluations for coronary artery disease, pulmonary embolism, and aortic dissection within a single breath hold, independent of the heart rate. We conducted a randomized diagnostic trial to compare the efficiency of a comprehensive cardiothoracic CT examination in the evaluation of patients presenting to the emergency department with undifferentiated acute chest discomfort or dyspnea. We randomized the emergency department patients clinically scheduled to undergo a dedicated CT protocol to assess coronary artery disease, pulmonary embolism, or aortic dissection to either the planned dedicated CT protocol or a comprehensive cardiothoracic CT protocol. All CT examinations were performed using a 64-slice dual source CT scanner. The CT results were immediately communicated to the emergency department providers, who directed further management at their discretion. The subjects were then followed for the remainder of their hospitalization and for 30 days after hospitalization. Overall, 59 patients (mean age 51.2 ± 11.4 years, 72.9% men) were randomized to either dedicated (n = 30) or comprehensive (n = 29) CT scanning. No significant difference was found in the median length of stay (7.6 vs 8.2 hours, p = 0.79), rate of hospital discharge without additional imaging (70% vs 69%, p = 0.99), median interval to exclusion of an acute event (5.2 vs 6.5 hours, p = 0.64), costs of care (p = 0.16), or the number of revisits (p = 0.13) between the dedicated and comprehensive arms, respectively. In addition, radiation exposure (11.3 mSv vs 12.8 mSv, p = 0.16) and the frequency of incidental findings requiring follow-up (24.1% vs 33.3%, p = 0.57) were similar between the 2 arms. Comprehensive cardiothoracic CT scanning was feasible, with a similar diagnostic yield to dedicated protocols. However, it did not reduce the length of stay, rate of subsequent testing, or costs. In conclusion, although this "triple rule out" protocol might be helpful in the evaluation of select patients, these findings suggest that it should not be used routinely with the expectation that it will improve efficiency or reduce resource use.
• 1.42

  Impact points

  Smaller and deeper lesions increase the number of acquired scan series in computed tomography-guided lung biopsy.

  Conor J Walsh, Bishnu H Sapkota, Mannudeep K Kalra, Nevan C Hanumara, Bob Liu, Jo-Anne O Shepard, Rajiv Gupta

  Journal of thoracic imaging. 01/2011; 26(3):196-203.

  To determine factors influencing the number of acquired scan series and subsequently the radiation dose and time during computed tomography (CT)-guided lung biopsies. This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, retrospective study reviewed... [more] To determine factors influencing the number of acquired scan series and subsequently the radiation dose and time during computed tomography (CT)-guided lung biopsies. This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, retrospective study reviewed 50 consecutive procedures. Each procedure was separated into the following steps: trajectory planning, needle placement, needle insertion (extrapulmonary and intrapulmonary), and sampling and follow-up. The number of scan series, time, and radiation dose were calculated for each procedure and its steps. The effects of patient characteristics (age, sex, history of surgery that violated the pleura), procedure characteristics (needle-pleural angle, patient position), and lesion characteristics (size, depth, lobar location) on the number of scan series for the procedure and each step were evaluated using stepwise linear regression. The overall diagnostic accuracy, pneumothorax rate, and chest tube insertion rate were also calculated. The mean number of total CT scans was 21, the mean effective dose was 14 mSv, and the mean entrance skin dose was 249 mGy. On average, trajectory planning and needle insertion contributed most to the number of scan series (18.5% and 52.9%, respectively). For trajectory planning, a smaller lesion size and shallower needle-pleural angle were associated with an increased number of scans (R(2)=0.200, P=0.005). During needle insertion, smaller lesions were associated with increased scanning (R(2)=0.296, P<0.001), with both smaller and deeper lesions associated with an increased number of scans during the intrapulmonary component (R(2)=0.372, P<0.001). For the entire procedure, smaller lesions were associated with an increased number of scans (R(2)=0.12, P=0.01). Lesions that are smaller or deeper in the lung result in a higher number of CT scans, resulting in increased radiation dose and procedure time, with most of these performed during the needle insertion step.
• 6.34

  Impact points

  Women with anorexia nervosa: finite element and trabecular structure analysis by using flat-panel volume CT.

  Conor J Walsh, Catherine M Phan, Madhusmita Misra, Miriam A Bredella, Karen K Miller, Pouneh K Fazeli, Harun H Bayraktar, Anne Klibanski, Rajiv Gupta

  Radiology. 10/2010; 257(1):167-74.

  To use finite element modeling based on flat-panel volume computed tomography (CT) and bone mineral density (BMD) provided by dual-energy x-ray absorptiometry (DXA) to compare bone failure load, stiffness, and trabecular structure in women with anorexia nervosa (AN) and age-matched normal-weight con... [more] To use finite element modeling based on flat-panel volume computed tomography (CT) and bone mineral density (BMD) provided by dual-energy x-ray absorptiometry (DXA) to compare bone failure load, stiffness, and trabecular structure in women with anorexia nervosa (AN) and age-matched normal-weight control subjects. The study was approved by the institutional review board and complied with HIPAA guidelines. Informed consent was obtained. Fourteen women, eight with AN (mean age, 26.6 years) and six control subjects (mean age, 26.3 years), underwent flat-panel volume CT of the distal radius to determine apparent trabecular bone volume fraction (BV/TV), apparent trabecular number (TbN), apparent trabecular thickness (TbTh), and apparent trabecular separation (TbSp). Bone strength and stiffness were calculated from uniaxial compression tests by using finite element models created from flat-panel volume CT. DXA was used to determine BMD of the radius, lumbar spine, and hip. Means ± standard deviations of all variables were calculated for both groups and compared (Student t test). Univariate regression analysis and stepwise regression modeling were performed. Patients with AN had lower values for stiffness (284.77 kN/mm ± 76.14 vs 389.97 kN/mm ± 84.90, P = .04), failure load (4.98 kN ± 1.23 vs 7.01 kN ± 1.52, P = .02), BV/TV (0.32% ± 0.09 vs 0.44% ± 0.02, P = .007), and TbN (1.15 mm(-3) ± 0.20 vs 1.43 mm(-3) ± 0.13, P = .008) and higher values for TbSp (0.62 mm ± 0.20 vs 0.40 mm ± 0.04, P = .02) compared with normal-weight control subjects. TbTh was lower in women with AN (P = .1). BMD measurements were significantly lower for the AN group. BMD measurements and trabecular parameters (except TbTh) correlated with stiffness and failure load (r = 0.58 to 0.83). Failure load and stiffness are abnormal in women with AN compared with those in normal-weight control subjects and correlate with BMD and trabecular parameters.
• 6.34

  Impact points

  Evaluation of dual-energy CT for differentiating intracerebral hemorrhage from iodinated contrast material staining.

  Rajiv Gupta, Catherine M Phan, Christianne Leidecker, Thomas J Brady, Joshua A Hirsch, Raul G Nogueira, Albert J Yoo

  Radiology. 10/2010; 257(1):205-11.

  To evaluate the efficacy of dual-energy computed tomography (CT) in the differentiation of intracerebral hemorrhage (ICH) from iodinated contrast material in patients who received contrast material via intraarterial or intravenous delivery. This retrospective study was approved by the local institut... [more] To evaluate the efficacy of dual-energy computed tomography (CT) in the differentiation of intracerebral hemorrhage (ICH) from iodinated contrast material in patients who received contrast material via intraarterial or intravenous delivery. This retrospective study was approved by the local institutional review board, which waived the informed consent requirement for the analysis. Sixteen patients with acute stroke and two with head trauma who had undergone intraarterial or intravenous administration of iodinated contrast material were evaluated by using dual-energy CT to differentiate areas of hyperattenuation secondary to contrast material staining from those representing ICH. A dual-energy CT scanner was used for imaging at 80 and 140 kV, and a three-material decomposition algorithm was used to obtain virtual unenhanced images and iodine overlay images. The sensitivity, specificity, and accuracy of dual-energy CT in the prospective differentiation of intraparenchymal contrast material from hemorrhage were obtained. Follow-up images were used as the standard of reference. There were 28 intraparenchymal areas of hyperattenuation classified at dual-energy CT as iodinated contrast material staining (n = 20, 71%), hemorrhage (n = 5, 18%), or both (n = 3, 11%). Two of the three areas of hyperattenuation seen on both virtual unenhanced and iodine overlay images were related to mineralization. The sensitivity, specificity, and accuracy of dual-energy CT in the identification of hemorrhage were 100% (six of six areas), 91% (20 of 22 areas), and 93% (26 of 28 areas), respectively. Dual-energy CT can help differentiate ICH from iodinated contrast material staining with high sensitivity and specificity in patients who have recently received intraarterial or intravenous iodinated contrast material.
• 2.78

  Impact points

  Fully automated intrinsic respiratory and cardiac gating for small animal CT.

  J Kuntz, J Dinkel, S Zwick, T Bäuerle, M Grasruck, F Kiessling, R Gupta, W Semmler, S H Bartling

  Physics in medicine and biology. 04/2010; 55(7):2069-85.

  A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-c... [more] A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.

• Discrepancies in reporting the vertebral level of abnormality in MR of the spine.

  Minal Jagtiani Sangwaiya, Shyla Saini, Rajiv Gupta, Albert J Yoo, Markus Stout, Keith Dreyer, Mannudeep Kalra

  Journal of the American College of Radiology : JACR. 10/2009; 6(10):715-20.

  PURPOSE: The aim of this study was to assess discrepancies in the spinal levels of abnormalities stated in the findings or impression (or both) sections of radiology reports of magnetic resonance (MR) imaging. MATERIALS AND METHODS: Radiology reports from January 2006 through December 2007 (n = 2,09... [more] PURPOSE: The aim of this study was to assess discrepancies in the spinal levels of abnormalities stated in the findings or impression (or both) sections of radiology reports of magnetic resonance (MR) imaging. MATERIALS AND METHODS: Radiology reports from January 2006 through December 2007 (n = 2,097,966) were analyzed using an online radiology report search engine. Reports were searched for presence of the key words MR spine and addendum. The addended reports were then manually assessed for any discrepancies in the reported spinal levels between the body and impression sections; the addenda corrected these errors (identified errors). In addition, all reports with the search term MR spine from January 2006 (n = 1,183) and January 2007 (n = 1,354) were assessed manually to recognize unidentified errors in spinal locations of reported pathology. Two neuroradiologists independently graded the clinical significance of errors on a 5-point scale (1 = definitely not significant, 5 = definitely significant). RESULTS: Of the 11,427 spinal MR reports analyzed in 2006, 7 had identified errors in the sites (levels of the spine) of the lesions. In 2007 (n = 11,785 spinal MR reports), 4 reports were detected with identified errors in spinal levels. In January 2006 and January 2007, 8 and 12 reports, respectively, had unidentified erroneous vertebral levels. Errors were related to discrepant vertebral regions (eg, cervical vs thoracic) in 16% of cases (5 of 31), the wrong number of vertebrae (eg, L2 instead of L3) in 68% of cases (21 of 31), and both in 16% of cases (5 of 31). The average time taken to issue an addendum was 5 +/- 7 days in 2006 and 11 +/- 13 days in 2007. Fifteen reports (48%) scored <3 on the scale of clinical significance, 1 report scored 3, and 15 scored >3. CONCLUSIONS: Errors in lesion level on spinal MR do occur in radiology reports. The number of unidentified errors is substantially higher than that of identified errors. Care should be taken before signing off on radiology reports to identify erroneous mentions of the vertebral levels of abnormalities.
• 4.09

  Impact points

  Hormone predictors of abnormal bone microarchitecture in women with anorexia nervosa.

  Elizabeth A Lawson, Karen K Miller, Miriam A Bredella, Catherine Phan, Madhusmita Misra, Erinne Meenaghan, Lauren Rosenblum, Daniel Donoho, Rajiv Gupta, Anne Klibanski

  Bone. 09/2009;

  Osteopenia is a complication of anorexia nervosa (AN) associated with a two- to three-fold increase in fractures. Nutritional deficits and hormonal abnormalities are thought to mediate AN-induced bone loss. Alterations in bone microarchitecture may explain fracture risk independent of bone mineral d... [more] Osteopenia is a complication of anorexia nervosa (AN) associated with a two- to three-fold increase in fractures. Nutritional deficits and hormonal abnormalities are thought to mediate AN-induced bone loss. Alterations in bone microarchitecture may explain fracture risk independent of bone mineral density (BMD). Advances in CT imaging now allow for noninvasive evaluation of trabecular microstructure at peripheral sites in vivo. Few data are available regarding bone microarchitecture in AN. We therefore performed a cross-sectional study of 23 women (12 with AN and 11 healthy controls) to determine hormonal predictors of trabecular bone microarchitecture. Outcome measures included bone microarchitectural parameters at the ultradistal radius by flat-panel Volume CT (fpVCT); BMD at the PA and lateral spine, total hip, femoral neck, and ultradistal radius by dual energy X-ray absorptiometry (DXA); and IGF-I, leptin, estradiol, testosterone, and free testosterone levels. Bone microarchitectural measures, including apparent (app.) bone volume fraction, app. trabecular thickness, and app. trabecular number, were reduced (p<0.03) and app. trabecular spacing was increased (p=0.02) in AN versus controls. Decreased structural integrity at the ultradistal radius was associated with decreased BMD at all sites (p</=0.05) except for total hip. IGF-I, leptin, testosterone, and free testosterone levels predicted bone microarchitecture. All associations between both IGF-I and leptin levels and bone microarchitectural parameters and most associations between androgen levels and microarchitecture remained significant after controlling for body mass index. We concluded that bone microarchitecture is abnormal in women with AN. Endogenous IGF-I, leptin, and androgen levels predict bone microarchitecture independent of BMI.
• 1.57

  Impact points

  Reproducibility of trabecular structure analysis using flat-panel volume computed tomography.

  Arnold Cheung, Miriam Bredella, Ma'moun Al Khalaf, Michael Grasruck, Christianne Leidecker, Rajiv Gupta

  Skeletal radiology. 06/2009;

  PURPOSE: To determine inter-scan, inter-reader and intra-reader variability of trabecular structure analysis using flat-panel volume computed tomography (fp-VCT) in cadaver knee specimens. METHODS: Five explanted knee specimens were imaged at three different time points using fp-VCT. Four parameters... [more] PURPOSE: To determine inter-scan, inter-reader and intra-reader variability of trabecular structure analysis using flat-panel volume computed tomography (fp-VCT) in cadaver knee specimens. METHODS: Five explanted knee specimens were imaged at three different time points using fp-VCT. Four parameters that quantify trabecular bone structure of the proximal tibia were measured by two observers at two different time points. Bland-Altman analysis was used to compute the inter-scan, inter-observer and intra-observer variability. RESULTS: Inter-scan variability was low, with a mean difference of 0% and a standard deviation less than 8.4% for each of the four parameters. The inter-observer and intra-observer variability was less than 2.8% +/- 8.5%. CONCLUSION: Fp-VCT is a method for assessing trabecular structure parameters with low inter-scan, inter-reader and intra-reader variability.
• 2.59

  Impact points

  Dynamic imaging of a model of intracranial saccular aneurysms using ultra-high-resolution flat-panel volumetric computed tomography.

  Alim P Mitha, Benjamin Reichardt, Michael Grasruck, Eric Macklin, Soenke Bartling, Christianne Leidecker, Bernhard Schmidt, Thomas Flohr, Thomas J Brady, Christopher S Ogilvy, Rajiv Gupta

  Journal of neurosurgery. 05/2009;

  Object Imaging of intracranial aneurysms using conventional multidetector CT (MDCT) is limited because of nonvisualization of features such as perforating vessels, pulsatile blebs, and neck remnants after clip placement or coil embolization. In this study, a model of intracranial saccular aneurysms ... [more] Object Imaging of intracranial aneurysms using conventional multidetector CT (MDCT) is limited because of nonvisualization of features such as perforating vessels, pulsatile blebs, and neck remnants after clip placement or coil embolization. In this study, a model of intracranial saccular aneurysms in rabbits was used to assess the ultra-high resolution and dynamic scanning capabilities of a prototype flat-panel volumetric CT (fpVCT) scanner in demonstrating these features. Methods Ten New Zealand white rabbits underwent imaging before and after clipping or coil embolization of surgically created aneurysms in the proximal right carotid artery. Imaging was performed using a prototype fpVCT scanner, a 64-slice MDCT scanner, and traditional catheter angiography. In addition to the slice data and 3D views, 4D dynamic views, a capability unique to fpVCT, were also created and reviewed. The images were subjectively compared on 1) 4 image quality metrics (spatial resolution, noise, motion artifacts, and aneurysm surface features); 2) 4 posttreatment features reflecting the metal artifact profile of the various imaging modalities (visualization of clip or coil placement, perianeurysmal clip/coil anatomy, neck remnant, and white-collar sign); and 3) 2 dynamic features (blood flow pattern and aneurysm pulsation). Results Flat-panel volumetric CT provided better image resolution than MDCT and was comparable to traditional catheter angiography. The surface features of aneurysms were demonstrated with much higher resolution, detail, and clarity by fpVCT compared with MDCT and angiography. Flat-panel volumetric CT was inferior to both MDCT and angiography in terms of image noise and motion artifacts. In fpVCT images, the metallic artifacts from clips and coils were significantly fewer than those in MDCT images. As a result, clinically important information about posttreatment aneurysm neck remnants could be derived from fpVCT images but not from MDCT images. Time-resolved dynamic sequences were judged slightly inferior to conventional angiography but superior to static MDCT images. Conclusions The spatial resolution, surface anatomy visualization, metal artifact profile, and 4D dynamic images from fpVCT are superior to those from MDCT. Flat-panel volumetric CT demonstrates aneurysm surface features to better advantage than angiography and is comparable to angiography in metal artifact profile. Even though the temporal resolution of fpVCT is not quite as good as that of angiography, fpVCT images yield clinically important anatomical information about aneurysm surface features and posttreatment neck remnants not attainable with either angiography or MDCT images.
• 4.64

  Impact points

  Towards regenerating a human thumb in situ.

  Christian Weinand, Rajiv Gupta, Eli Weinberg, Ijad Madisch, Craig Neville, Jesse B Jupiter, Joseph Vacanti

  Tissue engineering. Part A. 03/2009;

  Regenerative technology promises to alleviate the problem of limited donor supply for bone or organ transplants. Most expensive and time consuming is cell expansion in laboratories. We propose a method of magnetically enriched osteoprogenitor stem cells, dispersed in self-assembling hydrogels and ap... [more] Regenerative technology promises to alleviate the problem of limited donor supply for bone or organ transplants. Most expensive and time consuming is cell expansion in laboratories. We propose a method of magnetically enriched osteoprogenitor stem cells, dispersed in self-assembling hydrogels and applied onto new ultra-high resolution, jet-based 3D printing of living human bone in a single-step for in-situ bone regeneration. Human mesenchymal stem-cells (hBMSCs) were enriched with CD 117+ osteoprogenitor cells, dispersed in different collagen I, RAD 16I hydrogels mixes and applied onto 3-dimensional printed (3DP) beta-TCP/PLGA scaffolds, printed from ultra-high-resolution volumetric CT (VCT) images of a human thumb. Constructs were directly implanted subcutaneously into nude mice for 6 weeks. In-vivo radiographic VCT scanning and histological evaluations were performed at 1, 2, 4 and 6 weeks, expression of bone-specific genes and biomechanical compression-testing at 6 weeks endpoint. Time dependant accumulation of bone-like extracellular matrix was most evident in CD 117+ hBMSCs using collagen I/RAD 16I hydrogel mix. This was shown histologically by Toluidine blue, von Kossa and alkaline-phosphatase staining, paralleled by increased radiological densities within implants approximating that of human bone, and confirmed by high expression of bone-specific osteonectin and biomechanical stiffness at 6 weeks. Human origin of newly formed tissue was established by expression of human GAPDH using RT-PCR. Statistical analysis confirmed high correlations between biomechanical stiffness, radiological densities and bone-markers. Bone tissue can be successfully regenerated in-situ using a single-step procedure with constructs comprised of RAD 16I /collagen I hydrogel, CD 117+ enriched hBMSCs and porous beta-TCP/PLGA scaffolds.
• 6.34

  Impact points

  Distal radius in adolescent girls with anorexia nervosa: trabecular structure analysis with high-resolution flat-panel volume CT.

  Miriam A Bredella, Madhusmita Misra, Karen K Miller, Ijad Madisch, Ammar Sarwar, Arnold Cheung, Anne Klibanski, Rajiv Gupta

  Radiology. 12/2008; 249(3):938-46.

  PURPOSE: To examine trabecular microarchitecture with high-resolution flat-panel volume computed tomography (CT) and bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) in adolescent girls with anorexia nervosa (AN) and to compare these results with those in normal-weight control ... [more] PURPOSE: To examine trabecular microarchitecture with high-resolution flat-panel volume computed tomography (CT) and bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) in adolescent girls with anorexia nervosa (AN) and to compare these results with those in normal-weight control subjects. MATERIALS AND METHODS: The study was approved by the institutional review board and complied with HIPAA guidelines. Informed consent was obtained. Twenty adolescent girls, 10 with mild AN (mean age, 15.9 years; range, 13-18 years) and 10 age- and sex-matched normal-weight control subjects (mean age, 15.9 years; range, 12-18 years) underwent flat-panel volume CT of distal radius to determine apparent trabecular bone volume fraction (BV/TV), apparent trabecular number (TbN), apparent trabecular thickness (TbTh), and apparent trabecular separation (TbSp). All subjects underwent DXA of spine, hip, and whole body to determine BMD and body composition. The means and standard deviations (SDs) of structure parameters were calculated for AN and control groups. Groups were compared (Student t test). Linear regression analysis was performed. RESULTS: AN subjects compared with control subjects, respectively, showed significantly lower mean values for BV/TV (0.37% +/- 0.05 [SD] vs 0.46% +/- 0.03, P = .0002) and TbTh (0.31 mm +/- 0.03 vs 0.39 mm +/- 0.03, P < .0001) and higher mean values for TbSp (0.54 mm +/- 0.13 vs 0.44 mm +/- 0.04, P = .02). TbN was lower in AN subjects than in control subjects, but the difference was not significant (1.17 mm(-3) +/- 0.15 vs 1.22 mm(-3) +/- 0.07, P = .43). There was no significant difference in BMD between AN and control subjects. BMD parameters showed positive correlation with BV/TV and TbTh in the control group (r = 0.55-0.84, P = .05-.01) but not in AN patients. CONCLUSION: Flat-panel volume CT is effective in evaluation of trabecular structure in adolescent girls with AN and demonstrates that bone structure is abnormal in these patients compared with that in normal-weight control subjects despite normal BMD. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/249/3/938/DC1.
• 1.78

  Impact points

  Intrinsic gating for small-animal computed tomography: a robust ECG-less paradigm for deriving cardiac phase information and functional imaging.

  Julien Dinkel, Soenke H Bartling, Jan Kuntz, Michael Grasruck, Annette Kopp-Schneider, Masayoshi Iwasaki, Stefanie Dimmeler, Rajiv Gupta, Wolfhard Semmler, Hans-Ulrich Kauczor, Fabian Kiessling

  Circulation. Cardiovascular imaging. 11/2008; 1(3):235-43.

  BACKGROUND: A projection-based method of intrinsic cardiac gating in small-animal computed tomography imaging is presented. METHODS AND RESULTS: In this method, which operates without external ECG monitoring, the gating reference signal is derived from the raw data of the computed tomography project... [more] BACKGROUND: A projection-based method of intrinsic cardiac gating in small-animal computed tomography imaging is presented. METHODS AND RESULTS: In this method, which operates without external ECG monitoring, the gating reference signal is derived from the raw data of the computed tomography projections. After filtering, the derived gating reference signal is used to rearrange the projection images retrospectively into data sets representing different time points in the cardiac cycle during expiration. These time-stamped projection images are then used for tomographic reconstruction of different phases of the cardiac cycle. Intrinsic gating was evaluated in mice and rats and compared with extrinsic retrospective gating. An excellent agreement was achieved between ECG-derived gating signal and self-gating signal (coverage probability for a difference between the 2 measurements to be less than 5 ms was 89.2% in mice and 85.9% in rats). Functional parameters (ventricular volumes and ejection fraction) obtained from the intrinsic and the extrinsic data sets were not significantly different. The ease of use and reliability of intrinsic gating were demonstrated via a chemical stress test on 2 mice, in which the system performed flawlessly despite an increased heart rate. Because of intrinsic gating, the image quality was improved to the extent that even the coronary arteries of mice could be visualized in vivo despite a heart rate approaching 430 bpm. Feasibility of intrinsic gating for functional imaging and assessment of cardiac wall motion abnormalities was successfully tested in a mouse model of myocardial infarction. CONCLUSIONS: Our results demonstrate that self-gating using advanced software postprocessing of projection data promises to be a valuable tool for rodent computed tomography imaging and renders ECG gating with external electrodes superfluous.

  Download
• 6.34

  Impact points

  Calcified Plaque: Measurement of Area at Thin-Section Flat-Panel CT and 64-Section Multidetector CT and Comparison with Histopathologic Findings.

  Ammar Sarwar, Johannes Rieber, Eline A Q Mooyaart, Sujith K Seneviratne, Stuart L Houser, Fabian Bamberg, O Christopher Raffel, Rajiv Gupta, Mannudeep K Kalra, Homer Pien, Hang Lee, Thomas J Brady, Udo Hoffmann

  Radiology. 09/2008;

  The purpose of this study was to assess the blooming artifacts in ex vivo coronary arteries at multidetector computed tomography (CT) and flat-panel-volume CT by comparing measured areas of calcified plaque with respect to the reference standard of histopathologic findings. Three ex vivo hearts were... [more] The purpose of this study was to assess the blooming artifacts in ex vivo coronary arteries at multidetector computed tomography (CT) and flat-panel-volume CT by comparing measured areas of calcified plaque with respect to the reference standard of histopathologic findings. Three ex vivo hearts were scanned with multidetector CT and flat-panel-volume CT after institutional review board approval. The area of calcified plaque was measured at histopathologic examination, multidetector CT, and flat-panel-volume CT. The plaque area was overestimated at multidetector CT by 400% (4.61/1.15) on average, and the predicted difference between the measurements was significant (3.46 mm(2), P = .018). The average overestimation of plaque area at flat-panel-volume CT was twofold (214% [2.18/1.02]), and the predicted difference was smaller (1.16 mm(2), P = .08). The extent of the blooming artifact in visualizing calcified coronary plaque is reduced by using flat-panel-volume CT. (c) RSNA, 2008.
• 3.59

  Impact points

  Intrinsic respiratory gating in small-animal CT.

  Soenke H Bartling, Julien Dinkel, Wolfram Stiller, Michael Grasruck, Ijad Madisch, Hans-Ulrich Kauczor, Wolfhard Semmler, Rajiv Gupta, Fabian Kiessling

  European radiology. 08/2008; 18(7):1375-84.

  Gating in small-animal CT imaging can compensate artefacts caused by physiological motion during scanning. However, all published gating approaches for small animals rely on additional hardware to derive the gating signals. In contrast, in this study a novel method of intrinsic respiratory gating of... [more] Gating in small-animal CT imaging can compensate artefacts caused by physiological motion during scanning. However, all published gating approaches for small animals rely on additional hardware to derive the gating signals. In contrast, in this study a novel method of intrinsic respiratory gating of rodents was developed and tested for mice (n=5), rats (n=5) and rabbits (n=2) in a flat-panel cone-beam CT system. In a consensus read image quality was compared with that of non-gated and retrospective extrinsically gated scans performed using a pneumatic cushion. In comparison to non-gated images, image quality improved significantly using intrinsic and extrinsic gating. Delineation of diaphragm and lung structure improved in all animals. Image quality of intrinsically gated CT was judged to be equivalent to extrinsically gated ones. Additionally 4D datasets were calculated using both gating methods. Values for expiratory, inspiratory and tidal lung volumes determined with the two gating methods were comparable and correlated well with values known from the literature. We could show that intrinsic respiratory gating in rodents makes additional gating hardware and preparatory efforts superfluous. This method improves image quality and allows derivation of functional data. Therefore it bears the potential to find wide applications in small-animal CT imaging.

  Download
• 1.57

  Impact points

  Musculoskeletal applications of flat-panel volume CT.

  Benjamin Reichardt, Ammar Sarwar, Soenke Bartling, Arnold Cheung, Michael Grasruck, Christianne Leidecker, Miriam Bredella, Thomas Brady, Rajiv Gupta

  Skeletal radiology. 05/2008;

  Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volume... [more] Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).
• 1.23

  Impact points

  Large scan field, high spatial resolution flat-panel detector based volumetric CT of the whole human skull base and for maxillofacial imaging.

  S H Bartling, O Majdani, R Gupta, T Rodt, C Dullin, P F Fitzgerald, H Becker

  Dento maxillo facial radiology. 10/2007; 36(6):317-27.

  OBJECTIVES: To assess the feasibility of flat-panel detector based volumetric CT (fpVCT) scanning of the whole human skull base and maxillofacial region, which has thus far only been demonstrated on small, excised specimens. Flat-panel detectors offer more favourable imaging properties than image in... [more] OBJECTIVES: To assess the feasibility of flat-panel detector based volumetric CT (fpVCT) scanning of the whole human skull base and maxillofacial region, which has thus far only been demonstrated on small, excised specimens. Flat-panel detectors offer more favourable imaging properties than image intensifiers. It is therefore likely that they will replace them in cone-beam CT scanners that are currently used to scan parts of the skull base and maxillofacial region. Furthermore, the resolution of current CT imaging limits diagnosis, surgical planning and intraoperative navigation within these regions. fpVCT might overcome these limitations because it offers higher resolution of high contrast structures than current CT. METHODS: Three embalmed cadaver heads were scanned in two scanners: an experimental fpVCT that offers a scan field large enough for a whole human head, and in a current multislice CT (MSCT). 28 structures were compared. RESULTS: Both scanners produced bone images of diagnostic quality. Small high contrast structures such as parts of the ossicular chain and thin bony laminas were better delineated in fpVCT than in MSCT. fpVCT of maxillofacial region and skull base was rated superior to MSCT (P=0.002) as found in this limited, experimental study. CONCLUSIONS: High spatial resolution fpVCT scanning of both regions in a whole human head is feasible and might be slightly superior to MSCT. fpVCT could improve diagnostic accuracy in selected cases, as well as surgical planning and intraoperative navigation accuracy.

  Download