Damiano Caruso

Cinematic Rendering in CT: A Novel, Lifelike 3D Visualization Technique

OBJECTIVE The purpose of this article is to present an overview of cinematic rendering, illustrating its potential advantages and applications. CONCLUSION Volume-rendered reconstruction, obtaining 3D visualization from original CT datasets, is increasingly used by physicians and medical educators in various clinical and educational scenarios. Cinematic rendering is a novel 3D rendering algorithm that simulates the propagation and interaction of light rays as they pass through the volumetric data, showing a more photorealistic representation of 3D images than achieved with standard volume rendering.

The optimal contrast media policy in CT of the liver. Part I: Technical notes

Latest developments of multidetector computed tomography (MDCT), which is today considered a real volumetric technique, have revolutionized abdominal imaging. Technological improvements such as higher spatial resolution, larger volume coverage and higher temporal resolution, have reduced scan times allowing CT studies of the abdomen within a single breath-hold. Furthermore, the increased number of slices, the submillimetric collimation, and the use of multiple dynamic post-contrast phases per single examination, may all contribute to increase the radiation exposure of single patients. The aim of this review is to discuss different parameters affecting contrast media enhancement, as vascular enhancement, parenchymal enhancement and timing, in order to minimize the amount of contrast medium injected and the radiation exposure.

Optimization of window settings for virtual monoenergetic imaging in dual-energy CT of the liver: A multi-reader evaluation of standard monoenergetic and advanced imaged-based monoenergetic datasets.

OBJECTIVES To evaluate optimal window settings for display of virtual monoenergetic reconstructions in third-generation dual-source, dual-energy computed tomography (DECT) of the liver. METHODS Twenty-nine subjects were prospectively evaluated with DECT in arterial (AP) and portal venous (PVP) phases. Three reconstructed datasets were calculated: standard linearly-blended (LB120), 70-keV standard virtual monoenergetic (M70), and 50-keV advanced image-based virtual monoenergetic (M50+). Two readers assessed optimal window settings (width and level, W/L), establishing a mean for each reconstruction which was used for a blinded assessment of liver lesions. RESULTS The optimal W/L for M50+ were significantly higher for both AP (W=429.3 ± 44.6 HU, L=129.4 ± 9.7 HU) and PVP (W=376.1 ± 14.2HU, L=146.6 ± 7.0 HU) than for LB120 (AP, W=215.9 ± 16.9 HU, L=82.3 ± 9.4 HU) (PVP, W=173.4 ± 8.9 HU, L=69.3 ± 6.0 HU) and M70 (AP, W=247.1 ± 22.2 HU, L=72.9 ± 6.8 HU) (PVP, W=232.0 ± 27.9 HU, L=91.6 ± 14.4 HU). Use of the optimal window setting for M50+ vs. LB120 resulted in higher sensitivity (AP, 100% vs. 86%; PVP, 96% vs. 63%). CONCLUSIONS Application of dedicated window settings results in improved liver lesion detection rates in advanced image-based virtual monoenergetic DECT when customized for arterial and portal venous phases.

Virtual unenhanced imaging of the liver with third-generation dual-source dual-energy CT and advanced modeled iterative reconstruction

OBJECTIVES To compare image quality and diagnostic accuracy for the detection of liver lesions of virtual unenhanced (VU) images based on third-generation dual-source dual- energy computed tomography (DECT) compared to conventional unenhanced (CU) images. METHODS Thirty patients underwent triphasic abdominal CT consisting of single-energy CU (120kV, 147 ref.mAs) and dual-energy CT arterial and portal-venous phase acquisitions (100/Sn150kV, 180/90 ref.mAs). VU images were generated from arterial (AVU) and portal venous (PVU) phases. CU, AVU and PVU datasets were reconstructed. Quantitative image quality analysis was performed and two abdominal radiologists independently analyzed all datasets to evaluate image quality and identify liver lesions. Radiation dose was recorded and potential radiation dose reduction was estimated. RESULTS Image quality was rated diagnostic in 100% of the VU datasets. The mean subjective image quality of the CU datasets was higher than that of VU images (p<0.0001). No significant difference was observed in the mean attenuation values of the liver parenchyma (p>0.99) and hypoattenuating liver lesions (p≥0.21) between CU, AVU and PVU. However, a significant reduction in the attenuation values of calcified lesions (p<0.0001), metallic clips (p<0.0001) and gallstones (p≤0.047) was observed in the AVU and PVU images compared with CU images. A total of 122 liver lesions were found in 25 patients. VU images were more sensitive than CU images for detection of small hypoattenuating liver lesions (≤1cm). However, CU images were more sensitive than VU for calcified liver lesions. The mean radiation dose reduction achievable by avoiding the unenhanced acquisition was 32.9%±1.1% (p<0.01). CONCLUSIONS Third-generation DSCT VU images of the liver provide diagnostic image quality and improve small (≤1cm) liver lesion detection; however calcified liver lesions can be missed due to complete subtraction.

Myocardial perfusion imaging with dual energy CT

Dual-energy CT (DECT) enables simultaneous use of two different tube voltages, thus different x-ray absorption characteristics are acquired in the same anatomic location with two different X-ray spectra. The various DECT techniques allow material decomposition and mapping of the iodine distribution within the myocardium. Static dual-energy myocardial perfusion imaging (sCTMPI) using pharmacological stress agents demonstrate myocardial ischemia by single snapshot images of myocardial iodine distribution. sCTMPI gives incremental values to coronary artery stenosis detected on coronary CT angiography (CCTA) by showing consequent reversible or fixed myocardial perfusion defects. The comprehensive acquisition of CCTA and sCTMPI offers extensive morphological and functional evaluation of coronary artery disease. Recent studies have revealed that dual-energy sCTMPI shows promising diagnostic accuracy for the detection of hemodynamically significant coronary artery disease compared to single-photon emission computed tomography, invasive coronary angiography, and cardiac MRI. The aim of this review is to present currently available DECT techniques for static myocardial perfusion imaging and recent clinical applications and ongoing investigations.

Dynamic CT myocardial perfusion imaging

Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT based technologies. Coronary CT angiography has been shown to reliably assess coronary anatomy and detect high risk coronary artery disease. However, this technique is limited to anatomical assessment, thus non-invasive techniques for functional assessment of the heart are necessary. CT myocardial perfusion is a new CT based technique that provides functional assessment of the myocardium and allows for a comprehensive assessment of coronary artery disease with a single modality when combined with CTA. This review aims to discuss dynamic CT myocardial perfusion as a new technique in the assessment of CAD.

The optimal contrast media policy in CT of the liver. Part II: Clinical protocols

The advent of multidetector computed tomography (MDCT) revolutionized abdominal imaging. In particular, the definitive assessment of CT injection protocols, for the evaluation of the liver parenchyma, is still a critical issue for radiologists. Over the last years, this feature encouraged several authors to address their efforts to find the most accurate delay between the contrast medium injection and the effective scan-start, for the identification and characterization of liver lesions. Technological developments of the present century such as number of slices, submillimetric collimation, and the use of multiple dynamic post-contrast phases per single examination, may all contribute to increase the radiation exposure of single patients. The aim of this review is to propose liver imaging protocols, taking into consideration different clinical needs such as patients with chronic liver disease, healthy patients with focal liver lesion, and oncological patients to minimize radiation exposure. Finally, two recent innovations in MDCT which illustrate the potential application of multi-energy computed tomography (MECT) and perfusion computed tomography (CTp) when evaluating liver parenchyma will be discussed in a short closing paragraph.

T(Rho) and magnetization transfer and INvErsion recovery (TRAMINER)-prepared imaging: A novel contrast-enhanced flow-independent dark-blood technique for the evaluation of myocardial late gadolinium enhancement in patients with myocardial infarction.

To evaluate a new dark‐blood late gadolinium enhancement (LGE) technique called “T(Rho) And Magnetization transfer and INvErsion Recovery” (TRAMINER) for the ability to detect myocardial LGE versus standard “bright‐blood” inversion recovery (SIR) imaging.

Vascular Imaging Before Transcatheter Aortic Valve Replacement (TAVR): Why and How?

Transcatheter aortic valve replacement (TAVR) has become an alternative to surgical intervention for symptomatic or severe aortic valve stenosis in patients with high surgical risk. Successful TAVR requires a multimodality imaging approach for appropriate patient selection and prosthesis sizing. Here, we describe individual imaging modalities and report their respective roles in this emerging field. To date, echocardiography remains the traditional test for determining patient candidacy and prosthesis selection, but computed tomography (CT) has been taking on an increasingly important role in the evaluation of both the aortic root anatomy and aortoiliofemoral vessels as a single examination. Cardiac magnetic resonance (CMR) is useful in grading the severity of aortic stenosis and should be considered a reasonable alternative to CT for the evaluation of the aortic annulus, e.g., when the administration of contrast media is contraindicated.

High concentration (400 mgI/mL) versus low concentration (320 mgI/mL) iodinated contrast media in multi detector computed tomography of the liver: A randomized, single centre, non-inferiority study

OBJECTIVES To compare vascular and parenchymal contrast enhancement in multidetector computed tomography of the liver using two contrast media with different iodine concentration (Iodixanol 320 mgI/mL and Iomeprol 400 mgI/mL) and similar viscosity, using fixed total iodine volume (40 gI) and iodine delivery rate (1.6 gI/s). METHODS 110 patients were prospectively randomized into two groups. Group A received 125 mL of Iodixanol 320 and group B 100 mL of Iomeprol 400. Attenuation values were measured at the level of the aorta, portal vein and liver parenchyma on unenhanced, arterial, portal and equilibrium phases. A non inferiority test was performed on the differences between the two groups. An independent reader evaluated image quality. RESULTS The equivalence of the two CM was demonstrated in all measurements. Higher, but not statistically significant, attenuation values were obtained with Iomeprol 400 in the aorta during the arterial phase (305.3 HU versus 288.4 HU; P=0.32) and with Iodixanol 320 in the liver parenchyma, during both portal (59.8 HU versus 65.5 HU; P=0.78) and equilibrium (40.4 HU versus 41.8 HU; P=0.55) phases. CONCLUSIONS Iodixanol 320 and Iomeprol 400 injected at the same iodine delivery rate (1.6 gI/s) and total iodine load (40 gI) did not provide statistically significant differences in liver parenchymal and vascular contrast enhancement.