Noninvasive Tomographic Imaging Research Articles

The use of non-invasive tomographic imaging to monitor lung condition

The development of ultrasound tomography (UST) aimed to significantly enhance the precision and safety of non-invasive UST imaging, particularly for studying crystallization processes in biological tissues. The initiative sought to address the limitations of previous versions by incorporating advanced technological upgrades and providing a more user-friendly interface. The revised system comprises eight four-channel measurement cards interconnected via a high-speed FD CAN bus capable of 8 MBPS data transfer. Each card features a dedicated square wave generator, band-pass filters tailored to specific ultrasonic transducer frequencies, and a sophisticated signal envelope processing unit. The core processing unit is built around a 32-bit STM32G474RE microcontroller, ensuring robust data handling and image reconstruction capabilities. The UST device presented demonstrates improved image clarity and reduced noise interference. The measurement card redesign has achieved a sampling rate of 4 MBPS per channel and includes a two-stage amplification for dynamic range management. Upgraded power components, comprehensive shielding, and the integration of advanced analog switches have led to an enhanced signal-to-noise ratio, pivotal for high-resolution imaging. The advancements presented in the UST device mark a noteworthy progression in ultrasound imaging technology, extending beyond traditional applications. High-speed data collection, precise signal processing, and user-centered design have all come together to make a system that can image crystallization processes more accurately and accurately over and over again.

The fantastic voyage of solid lipid nanoparticles from the lung to the brain: non-invasive tomographic imaging as a feasible refinement process

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Reconstruction of particle positions and orientations from 3D MRI images of non-spherical particle packings

Packed bed reactors of non-spherical particles are widely used in chemical industry with the aim to obtain a high active surface area and achieve a homogeneous flow. Despite this, little is known about the arrangement of particles within the bed and the influence of this arrangement on the fluid flow distribution. Magnetic Resonance Imaging (MRI) is a non-invasive tomographic imaging technique that allows 3D visualisation of the packing and flow structure. However, the individual particle information is not obtained using MRI. In this work we investigate different particle detection methods to retrieve the particle position and orientation from MRI images. Results show the successful reconstruction of random packing structures of various non-spherical particle shapes: ellipsoid, spherocylinder, cylinder and cube. The applicability of each method in relation to the particle shape, as well as strengths and drawbacks of each particle detection method are discussed. This paper shows the ability to reconstruct real packed beds of non-spherical particle shapes from MRI images, which opens several research opportunities in the field of chemical engineering.

Cell Tracking by Magnetic Particle Imaging: Methodology for Labeling THP-1 Monocytes with Magnetic Nanoparticles for Cellular Imaging.

Magnetic particle imaging (MPI) is a noninvasive tomographic imaging modality for the quantitative visualization of magnetic nanoparticles (MNPs) with high temporal and spatial resolution. The general capability of MPI for cell tracking (e.g., monitoring living cells labeled with MNPs) has successfully been shown. MNPs in cell culture media are often subjected to structural and magnetic changes. In addition to the deteriorating reproducibility, this also complicates the systematic study of the relationship between the MNP properties and their cellular uptake for MPI. Here, we present a method for the preparation of magnetically labeled THP-1 (Tamm–Horsfall Protein-1) monocytes that are used in MPI cell tracking. The method development was performed using two different MPI tracers, which exhibited electrostatic and steric stabilizations, respectively. In the first step, the interaction between the MNPs and cell culture media was investigated and adjusted to ensure high structural and magnetic stability. Furthermore, the influences of the incubation time, MNP concentration used for cellular uptake, and individual preparation steps (e.g., the washing of cells) were systematically investigated. Finally, the success of the developed loading method was demonstrated by the MPI measurements. The presented systematic investigation of the factors that influence the MNP loading of cells will help to develop a reliable and reproducible method for MPI monocyte tracking for the early detection of inflammation in the future.

Characterizing the Impact of Spray Dried Particle Morphology on Tablet Dissolution Using Quantitative X-Ray Microscopy

For oral solid dosage forms, disintegration and dissolution properties are closely related to the powders and particles used in their formulation. However, there remains a strong need to characterize the impact of particle structures on tablet compaction and performance. Three-dimensional non-invasive tomographic imaging plays an increasingly essential role in the characterization of drug substances, drug product intermediates, and drug products. It can reveal information hidden at the micro-scale which traditional characterization approaches fail to divulge due to a lack of resolution. In this study, two batches of spray-dried particles (SDP) and two corresponding tablets of an amorphous product, merestinib (LY2801653), were analyzed with 3D X-Ray Microscopy. Artificial intelligence-based image analytics were used to quantify physical properties, which were then correlated with dissolution behavior. The correlation derived from the image-based characterization was validated with conventional laboratory physical property measurements. Quantitative insights obtained from image-analysis including porosity, pore size distribution, surface area and pore connectivity helped to explain the differences in dissolution behavior between the two tablets, with root causes traceable to the microstructure differences in their corresponding SDPs.

Cellular-resolution in vivo tomography in turbid tissue through digital aberration correction

Noninvasive tomographic imaging of cellular processes in vivo may provide valuable cytological and histological information for disease diagnosis. However, such strategies are usually hampered by optical aberrations caused by the imaging system and tissue turbidity. State-of-the-art aberration correction methods require that the light signal be phase stable over the full-field data acquisition period, which is difficult to maintain during dynamic cellular processes in vivo. Here we show that any optical aberrations in the path length difference (OPD) domain can be corrected without the phase stability requirement based on maximum intensity assumption. Specifically, we demonstrate a novel optical tomographic technique, termed amplitude division aperture synthesis optical coherence tomography (ADAS-OCT), which corrects aberrations induced by turbid tissues by physical aperture synthesis and simultaneously data acquisition from sub-apertures. Even with just two sub-apertures, ADAS-OCT enabled in vivo visualization of red blood cells in human labial mucosa. We further demonstrated that adding sub-apertures could significantly scale up the aberration correction capability. This technology has the potential to impact a number of clinical areas where noninvasive examinations are preferred, such as blood count and cancers detection.

Robust Recovery of Temporal Overlap Between Network Activity Using Transient-Informed Spatio-Temporal Regression.

Functional magnetic resonance imaging is a non-invasive tomographic imaging modality that has provided insights into system-level brain function. New analysis methods are emerging to study the dynamic behavior of brain activity. The innovation-driven co-activation pattern (iCAP) approach is one such approach that relies on the detection of timepoints with a significant transient activity to subsequently retrieve spatially and temporally overlapping large-scale brain networks. To recover temporal profiles of the iCAPs for further time-resolved analysis, spatial patterns are fitted back to the activity-inducing signals. In this crucial step, spatial dependences can hinder the recovery of temporal overlapping activity. To overcome this effect, we propose a novel back-projection method that optimally fits activity-inducing signals given a set of transient timepoints and spatial maps of iCAPs, thus taking into account both spatial and temporal constraints. Validation on simulated data shows that transient-based constraints improve the quality of fitted time courses. Further evaluation on experimental data demonstrates that overfitting and underfitting are prevented by the use of optimized spatio-temporal constraints. Spatial and temporal properties of resulting iCAPs support that brain activity is characterized by the recurrent co-activation and co-deactivation of spatially overlapping large-scale brain networks. This new approach opens new avenues to explore the brain's dynamic core.

Noninvasive imaging analysis of biological tissue associated with laser thermal injury

BackgroundThe purpose of our study is to use a noninvasive tomographic imaging technique with high spatial resolution to characterize and monitor biological tissue responses associated with laser thermal injury. MethodsOptical doppler tomography (ODT) combines laser doppler flowmetry (LDF) with optical coherence tomography (OCT) to obtain high resolution tomographic velocity and structural images of static and moving constituents in highly scattering biological tissues. A SurgiLase XJ150 carbon dioxide (CO2) laser using a continuous mode of 3 watts (W) was used to create first, second or third degree burns on anesthetized Sprague–Dawley rats. Additional parameters for laser thermal injury were assessed as well. ResultsThe rationale for using ODT in the evaluation of laser thermal injury offers a means of constructing a high resolution tomographic image of the structure and perfusion of laser damaged skin. In the velocity images, the blood flow is coded at 1300 μm/s and 0 velocity, 1000 μm/s and 0 velocity, 700 μm/s and 0 velocity adjacent to the first, second, and third degree injuries, respectively. ConclusionODT produces exceptional spatial resolution while having a non-invasive way of measurement, therefore, ODT is an accurate measuring method for high-resolution fluid flow velocity and structural images for biological tissue with laser thermal injury.

Image-guided therapies for myocardial repair: concepts and practical implementation

Cell- and molecule-based therapeutic strategies to support wound healing and regeneration after myocardial infarction (MI) are under development. These emerging therapies aim at sustained preservation of ventricular function by enhancing tissue repair after myocardial ischaemia and reperfusion. Such therapies will benefit from guidance with regard to timing, regional targeting, suitable candidate selection, and effectiveness monitoring. Such guidance is effectively obtained by non-invasive tomographic imaging. Infarct size, tissue characteristics, muscle mass, and chamber geometry can be determined by magnetic resonance imaging and computed tomography. Radionuclide imaging can be used for the tracking of therapeutic agents and for the interrogation of molecular mechanisms such as inflammation, angiogenesis, and extracellular matrix activation. This review article portrays the hypothesis that an integrated approach with an early implementation of structural and molecular tomographic imaging in the development of novel therapies will provide a framework for achieving the goal of improved tissue repair after MI.

Fluorescence Tomography of Rapamycin-Induced Autophagy and Cardioprotection In Vivo

Autophagy is a biological process during which cells digest organelles in their cytoplasm and recycle the constituents. The impact of autophagy in the heart, however, remains unclear in part because of the inability to noninvasively image this process in living animals. Here, we report the use of fluorescence molecular tomography and a cathepsin-activatable fluorochrome to image autophagy in the heart in vivo after ischemia/reperfusion and rapamycin (RAP) therapy. We show that cathepsin-B activity in the lysosome is upregulated by RAP and that this allows the expanded lysosomal compartment in autophagy to be imaged in vivo with fluorescence molecular tomography. We further demonstrate that the delivery of diagnostic nanoparticles to the lysosome by endocytosis is enhanced during autophagy. The upregulation of autophagy by RAP was associated with a 23% reduction (P<0.05) of apoptosis in the area at risk and a 45% reduction in final infarct size (19.6±5.6% of area at risk with RAP versus 35.9±9.1% of area at risk without RAP; P<0.05). The ability to perform noninvasive tomographic imaging of autophagy in the heart has the potential to provide valuable insights into the pathophysiology of autophagy, particularly its role in cardiomyocyte salvage. Although additional data are needed, our study supports the investigation of RAP therapy in patients with acute coronary syndromes.

Microtomographic Quantification of Hydraulic Clay Mineral Displacement Effects During a CO2 Sequestration Experiment with Saline Aquifer Sandstone

We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the core-flooding experiment at a spatial voxel resolution of 27 μm. No significant changes in microstructure were found at the tomographic imaging resolution including porosity and pore size distribution, except of an increase of depositional heterogeneous distribution of clay minerals in the pores. The digitized rock data were used as direct real microstructure input to the GeoDict software package, to simulate Navier-Stokes flow by a lattice Boltzmann equation solver. This procedure yielded 3D pressure and flow velocity fields, and revealed that the migration of clay particles decreased the permeability tensor probably due to clogging of pore openings.

Abstract 2448: Development of a red fluorescent labeled agent for assessing HER2 expression in vitro and in vivo

Abstract Upregulation of tumor HER2 occurs in approximately 25% women with breast cancer and is often associated with poor prognosis. We developed a red fluorescent imaging agent to non-invasively image and quantify tumor-associated HER2 expression in vivo. A red fluorescent dye (VivoTag 645; α=210,000 μ/cm; abs/em max 643/660 nm) was used to label trastuzumab, which is currently used to treat breast and stomach cancer. The red-labeled trastuzumab (VM4003) preferentially labeled HER2+ SKOV-3 human ovarian adenocarcinoma cells over HER2− human colorectal adenocarcinoma Colo-205 cells (10 fold), and the specificity of binding was confirmed by control experiments using free dye, labeled non-specific IgG, and competitive blockade with unlabeled excess trastuzumab. Fluorescence microscopy confirmed the expected membrane localization of fluorescence. In vivo and ex vivo imaging by fluorescence molecular tomography (FMT), showed significantly higher signal within the tumors, peaking at 6-72 hours following intravenous injection of 2 mg/kg VM4003, decreasing thereafter with a tissue half-life of 3 days. In vivo quantification of tumor signal in nude mice showed significantly higher tumor signal in HER2+ than in HER2− tumors (14.36 + 4 versus 2.39+ 0.74 pmol, at 6h imaging time, p=0.007; 18.77 + 4.45 versus 3.50+ 0.98 pmol, at 24h, p=0.001). Specificity of targeting was confirmed by competition with excess intravenous unlabeled trastuzumab, which achieved 70% signal inhibition in the tumors (tumor signal 16.12 + 3.03 versus 4.72 + 1.96 pmol, p=0.022 at 24h). Tumor volumes, as determined by direct measurements of tumor size, were comparable between both groups of mice (p=0.193). Fluorescence microscopy of ex vivo frozen tissue sections confirmed tumor fluorescence and signal localization associated to cell membranes and cytoplasm. In summary, red fluorescent-labeled trastuzumab selectively targets αER2, allowing both imaging in vitro and the non-invasive real-time tomographic imaging and quantification in vivo of HER-2 expression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2448. doi:1538-7445.AM2012-2448

3D evaluation of composite resin restoration at practical training using swept-source optical coherence tomography (SS-OCT)

Internal adaptation of restorations to the cavity wall is one of the important topics in clinical dentistry. The purpose of this study was to investigate the possibility to utilize the non-invasive tomographic imaging system for teaching the importance of cavity adaptation at dental school pre-clinical training. Swept-source optical coherence tomography (SS-OCT) was used for detection of marginal and internal defects in the composite resin restorations as an educational device. Class 1 and Class 2 composite restorations to melamine resin molar tooth were assigned to the students and prepared during the skill test, and SS-OCT imaging was performed to evaluate students' works. SS-OCT could detect the internal gaps and voids within the restorations in tomography images synthesized based on the backscatter signal from within the restoration. It is suggested that the SS-OCT is promising diagnostic modality, as well as educational imaging device for the detection of internal gaps in adhesive restorations.

Aortic intramural hematoma: aspects of pathogenesis 2011

Non-invasive tomographic imaging modalities have recently contributed to identifying aortic intramural hematoma, a variant form of classic dissection, which is characterized by the absence of an intimal tear and thus the absence of direct flow communication, and which represents an important disease entity in acute aortic syndrome. Clinical investigations have revealed that intramural hematoma has characteristic clinical features and that the natural remodeling process of hematoma is different from that of classic aortic dissection. These findings suggest that intramural hematoma is not just a precursor to aortic dissection, but may be a unique disease entity with a more favorable prognosis compared to aortic dissection. There is regional heterogeneity regarding the relative incidence of this hematoma, with higher incidence seen in Eastern countries. Due to favorable outcomes with medical treatment in Asian patients with type A intramural hematoma, a tailored or individualized approach based on risk stratification using initial clinical information and including imaging studies and timely surgical repair has been suggested in hemodynamically stable patients; however, these results need to be confirmed in other patient populations. The concept of a "micro-tear" which cannot be easily visualized using conventional imaging modalities has been raised: "echo-free space" on transesophageal echocardiography and "focal contrast enhancement" on ultra-fast computerized tomography have drawn many physicians' attention, and the possibility of a pathophysiologic link between classic aortic dissection and intramural hematoma has been discussed. Further investigations are needed to test whether intramural hematoma begins with an initial intimal tear and a different aortic status--characterized by a more rigid and non-compliant aorta associated with old age or long-standing hypertension--and results in an apparently absent intimal flap.

Quantitative Whole Body Biodistribution of Fluorescent-Labeled Agents by Non-Invasive Tomographic Imaging

When small molecules or proteins are injected into live animals, their physical and chemical properties will significantly affect pharmacokinetics, tissue penetration, and the ultimate routes of metabolism and clearance. Fluorescence molecular tomography (FMT) offers the ability to non-invasively image and quantify temporal changes in fluorescence throughout the major organ systems of living animals, in a manner analogous to traditional approaches with radiolabeled agents. This approach is best used with biotherapeutics (therapeutic antibodies, or other large proteins) or large-scaffold drug-delivery vectors, that are minimally affected by low-level fluorophore conjugation. Application to small molecule drugs should take into account the significant impact of fluorophore labeling on size and physicochemical properties, however, the presents studies show that this technique is readily applied to small molecule agents developed for far-red (FR) or near infrared (NIR) imaging. Quantification by non-invasive FMT correlated well with both fluorescence from tissue homogenates as well as with planar (2D) fluorescence reflectance imaging of excised intact organs (r2 = 0.996 and 0.969, respectively). Dynamic FMT imaging (multiple times from 0 to 24 h) performed in live mice after the injection of four different FR/NIR-labeled agents, including immunoglobulin, 20–50 nm nanoparticles, a large vascular imaging agent, and a small molecule integrin antagonist, showed clear differences in the percentage of injected dose per gram of tissue (%ID/g) in liver, kidney, and bladder signal. Nanoparticles and IgG1 favored liver over kidney signal, the small molecule integrin-binding agent favored rapid kidney and bladder clearance, and the vascular agent, showed both liver and kidney clearance. Further assessment of the volume of distribution of these agents by fluorescent volume added information regarding their biodistribution and highlighted the relatively poor extravasation into tissue by IgG1. These studies demonstrate the ability of quantitative FMT imaging of FR/NIR agents to non-invasively visualize and quantify the biodistribution of different agents over time.

Abstract LB-147: 18F-FAZA-PET as a pharmacodynamic biomarker of anti-tumor activity for the novel HIF-1α pathway inhibitor BAY 87–2243 in preclinical tumor models

Abstract BAY 87–2243 is a novel small molecule inhibitor of hypoxia inducible factor-1α (HIF-1α) activity. Preclinical studies with BAY 87–2243 in a number of murine tumor models showed moderate to high tumor growth inhibition. The present study describes a non-invasive positron emission tomographic (PET) imaging method that monitors early therapeutic efficacy of this drug. To identify optimal tracer(s) for monitoring BAY 87–2243 anti-tumor activity, female nude mice were implanted on both scapulae with either 3.5×106 human non-small cell lung cancer (H460) or 2×106 human prostate cancer cells (PC3). Both are growth-inhibited by BAY 87–2243. Xenografts were grown to 200 mm3 over 10 days. Four PET tracers were assessed for uptake into tumor xenografts: 18F-FDG, 18F-FPP(RGD)2, 18F-FLT and 18F-FAZA. Tracers were injected via the tail vein. After pre-scan, BAY 87–2243 was orally administered, daily at 9mg/kg to 7 days. Tracer uptake was examined 1 and 3 day(s) after initial administration. Each treatment group for each PET tracer tested consisted of 6 tumors in 3 animals. At each imaging time point, RNA from BAY 87–2243-treated and vehicle-treated H460 tumor xenografts (3 additional animals each) was isolated. HIF target genes were quantified by Real-Time polymerase chain (RT-PCR) reaction. For both 18F-FDG and 18F-FPP(RGD)2, uptake was not significantly altered. However, 18F-FAZA tumor uptake (%ID mean/g) declined by 55–70% (1.21 ± 0.10 %ID/g to 0.35 ± 0.1 %ID/g, n=6, vehicle vs. treatment) in both H460 (p&amp;lt;0.001) and PC3 (p&amp;lt;0.05) models at both 1 and 3 days after drug administration. The decline occurred before any significant difference in tumor volume between drug- and vehicle-treated animals was observed, thus suggesting that decline in 18F-FAZA uptake reflected early changes in tumor biochemistry. A similar observation was noted for 18F-FLT in the H460 model, although the decline was less pronounced (30%; p&amp;lt;0.05 for all time-points). Analysis of HIF target gene expression by RT-PCR revealed that BAY 87–2243 reduced expression of the hypoxia regulated genes CA IX and ANGPTL4 by 99 % and 93 % respectively (p&amp;lt;0.001 for both) which corresponds with reduced 18F-FAZA uptake upon drug treatment. Reduced 18F-FLT uptake was not accompanied by reduced expression of TK1. Expression level of genes associated with glucose metabolism was heterogeneous and did not fully match with unchanged 18F-FDG uptake: GLUT-1 expression was unchanged while HK-2 decreased by 75 % (p&amp;lt;0.01). We detected low ITGB3 expression in untreated xenografts but were unable to detect transcripts after BAY 87–2243 treatment. This findings may explain the lack of change in 18F-FPP(RGD)2 uptake. In conclusion, our pilot studies suggest the suitability of 18F-FAZA-PET to monitor the efficacy of anti-cancer agents targeting the HIF pathway (e.g. BAY 87–2243) as an early PD marker prior to changes in tumor volume Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-147. doi:10.1158/1538-7445.AM2011-LB-147

Multimodality Imaging Reveals a Gradual Increase in Matrix Metalloproteinase Activity at Aneurysmal Lesions in Live Fibulin-4 Mice

We imaged the protease activity of matrix metalloproteinases (MMPs) upregulated during aneurysm formation, using protease-activatable near-infrared fluorescence probes. We tested whether these protease-activatable sensors can directly report the in vivo activity of the key biomarkers in aneurysm, using our genetically modified fibulin-4 mouse models for aneurysm formation. Mice homozygous for the fibulin-4 reduced-expression allele (fibulin-4(R/R)) show dilatation of the ascending aorta and a tortuous, stiffened aorta resulting from disorganized elastic fiber networks. Strikingly, even a moderate reduction in expression of fibulin-4 in the heterozygous fibulin-4(+/R) mice occasionally results in modest aneurysm formation. Aorta transcriptome and protein expression analysis of fibulin-4(+/R) and fibulin-4(R/R) animals identified excessive transforming growth factor-β signaling as the critical event in the pathogenesis of aneurysm formation. To determine whether a perturbed elastin lamellar structure arose from induction of transforming growth factor-β-regulated MMPs, we performed gelatin zymography and used a protease-activatable near-infrared fluorescence probe to monitor and quantify MMP upregulation in animals, using various in vivo optical imaging modules and coregistration of the fluorescence signal with CT images of the same animals. Gelatin zymography demonstrated a significant increase in the presence of the active form of MMP-9 in the aortic arch of fibulin-4(R/R) mice. In vivo analysis of MMP upregulation using the near-infrared fluorescence probe and subsequent isosurface concentration mapping from reconstructed tomographic images from fibulin-4(+/R) and fibulin-4(R/R) mice revealed a graded increase in activation of MMPs within the aneurysmal lesions. We aimed to develop molecular imaging procedures for faster, earlier, and easier recognition of aortic aneurysms. We show that in vivo coregistration of MMP activity by noninvasive tomographic imaging methods allows the detection of increased MMP activity, even before the aneurysm has actually formed.

Immediate ex-vivo optical coherence tomography of suspicious oral lesions

The aim of this study was to compare findings of optical coherence tomography (OCT) with histopathology of various oral lesions to see if this technique could be used as an adjunct or alternative to histopathology in assessing oral dysplasia. The technique is a non-invasive interferometric tomographic imaging modality which allows millimetre penetration with micrometer-scale axial and lateral resolution.

2006 Charles T. Dotter Memorial Lecture—Cardiac Surgery: Pre- &amp; Post-Operative Insights From MR &amp; CT

Advancements in MR and CT imaging of the cardiovascular system have permitted unique insights into the appearance and behavior of the cardiac chambers, myocardium, coronary arteries, pericardium, and proximal great vessels in disease states directly involving or indirectly affecting (eg, such as due to valve disease) these structures. However, the impact of the 3D anatomic, functional, tissue-characterizing, or flow-quantification capabilities of these two noninvasive tomographic imaging modalities specifically on pre–cardiac surgery planning and/or post–cardiac surgery monitoring has not often been addressed. With concurrent advances in catheter-based therapy, there has been significant reduction in the volume of traditional cardiac surgical procedures such as coronary artery bypass grafting. Because of the life-saving nature of these surgical alternatives, traditional surgeries, and medical therapies, older patients with complicated medical histories, including prior interventions, leading to highly patient-specific cardiac conditions, are more and more commonly cardiac surgery candidates. Thus, there is increasing need for highly specialized and individualized imaging in order for cardiac surgeons to understand the specific details of such patients’ current cardiac anatomic and physiological abnormalities in the context of their past disease course and history of therapy to plan future surgical treatments. Cardiac surgical procedures performed at major heart centers that benefit from insights provided by cardiac MR and CT include ventricular restoration of the dilated dysfunctional left ventricle, myocardial revascularization of the chronically ischemic left ventricle, septal myectomy for hypertrophic obstructive cardiomyopathy, pericardiectomy for constrictive or adhesive pericardial disease, cardiac mass resection, and aortic root and/or valve replacement.

Visualising noncalcified coronary plaques by CT

Due to a rapid improvement of the new generation submillimetre multislice CT-technology noninvasive tomographic imaging of the coronary vessel wall has become reality. First clinical studies have shown the ability in particular of 16-slice CT to determine plaque burden, plaque composition and compensatory vessel-wall remodelling. These novel findings already constitute an important step forward to assess coronary atherosclerosis noninvasively in a detailed manner which opens promising new opportunities for a better understanding and riskstratification of coronary atherosclerosis. Current limitations, mainly the insufficient accuracy to detect small lesions in distal coronary segments, might be overcome by improved spatial and temporal resolution of the new generation scanners operating with 64 and more detectors.