scholarly journals The presence of contrast agent increases organ radiation dose in contrast-enhanced CT

2021 ◽  
Author(s):  
Mahta Mazloumi ◽  
Gert Van Gompel ◽  
Veerle Kersemans ◽  
Johan de Mey ◽  
Nico Buls
Keyword(s):  
Radiation Dose ◽  
Contrast Media ◽  
Contrast Agent ◽  
Linear Relation ◽  
Left Kidney ◽  
Organ Dose ◽  
Liver Parenchyma ◽  
Radiation Absorption ◽  
Contrast Enhanced ◽  
Absorbed Radiation Dose

Abstract Objectives Routine dosimetry calculations do not account for the presence of iodine in organs and tissues during CT acquisition. This study aims to investigate the impact of contrast agent (CA) on radiation dose. Methods First, relation between absorbed radiation dose and iodine concentrations was investigated using a cylindrical water phantom with iodine-saline dilution insertions. Subsequently, a retrospective study on abdominal dual-energy CT (DECT) patient data was performed to assess the increase of the local absorbed radiation dose compared to a non-contrast scan. Absorbed doses were estimated with Monte Carlo simulations using the individual CT voxel data of phantom and patients. Further, organ segmentations were performed to obtain the dose in liver, liver parenchyma, left kidney, right kidney, aorta, and spleen. Results In the phantom study, a linear relation was observed between the radiation dose normalized by computed tomography dose index (CTDI) and CA concentrations Iconc (mg/ml) for three tube voltages; $$ \frac{D_{80 kVp}}{CTDI_{vol}} $$ D 80 kVp CTDI vol = 0.14 × Iconc + 1.02, $$ \frac{D_{120 kVp}}{CTDI_{vol}} $$ D 120 kVp CTDI vol = 0.16 × Iconc + 1.21, $$ \frac{D_{140 kVp}}{CTDI_{vol}} $$ D 140 kVp CTDI vol = 0.16 × Iconc + 1.24, and for DECT acquisition; $$ \frac{D_{DECT}}{CTDI_{vol}} $$ D DECT CTDI vol = 0.15 × Iconc + 1.09. Similarly, a linear relation was observed between the dose increase and the organ iodine contents (R2 = 0.86 and pvalue < 0.01) in the patient study. The relative doses increased in the liver (21 ± 5%), liver parenchyma (20 ± 5%), right kidney (37 ± 7%), left kidney (39 ± 7%), aorta (34 ± 6%) and spleen (26 ± 4%). In addition, the local dose distributions changed based on patient’s anatomy and physiology. Conclusions Compared to a non-contrast scan, the organ doses increase by 30% in contrast-enhanced abdominal CT. This study suggests considering CA in dosimetry calculations, epidemiological studies, and organ dose estimations while developing new CT protocols. Key Points • The presence of contrast media increases radiation absorption in CT, and this increase is related to the iodine content in the organs. • The increased radiation absorption due to contrast media can lead to an average 30% increase in absorbed organ dose. • Iodine should be considered in CT radiation safety studies.

Ultrasound imaging with bolus delivered contrast agent for the detection of angiogenesis and blood flow irregularities

2014 ◽  
Vol 307 (8) ◽  
pp. H1226-H1232 ◽  
Author(s):  
Petra Korpisalo ◽  
Jarkko P. Hytönen ◽  
Johannes T. T. Laitinen ◽  
Johanna Närväinen ◽  
Tuomas T. Rissanen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Gene Therapy ◽  
Blood Flow ◽  
Gene Transfer ◽  
Contrast Media ◽  
Contrast Agent ◽  
Contrast Enhanced Ultrasound ◽  
Contrast Enhanced ◽  
Viral Particles ◽  
Angiogenic Gene

Highly increased blood flow and vascularity after angiogenic gene therapy have raised concerns of shunting and hemangioma-like blood pool formation that might decrease effective perfusion and ruin the beneficial effects of the therapy. Contrast enhanced ultrasound is a promising noninvasive tool for studying skeletal muscle perfusion. The objectives of the present study were to test bolus and infusion administrations of ultrasound microbubble contrast media in imaging vascular growth in skeletal muscle and assess the functionality of vessels grown with angiogenic gene therapy. Contrast enhanced ultrasound was used to study changes in skeletal muscle perfusion in normal and gene-transduced rabbit hindlimbs 6 days after gene transfer. Adenoviral gene transfer of VEGF (10 e9–10 e11 viral particles) or β-galactosidase control gene (10 e11 viral particles) was done under anesthesia and induced up to 16-fold increases in relative tissue perfusion. Contrast intensity versus time curves were plotted and analyzed for contrast kinetics. Bolus administration of the contrast media was highly feasible in analyzing skeletal muscle blood flow and its kinetics. Maximal signal intensity of the bolus signal reflected relative changes in both blood flow and volume equally to the infusion method. Flow irregularities were detected after angiogenic gene therapy. In conclusion, bolus delivery of ultrasound contrast agent is highly feasible for the relative analysis of both quantity and quality of blood flow after angiogenic gene therapy. The kinetics of blood flow can and should be studied more extensively in both preclinical and clinical trials of angiogenic gene therapy since there is increasing evidence of flow irregularities in angiogenic vessels.

scholarly journals Decreasing the radiation dose for contrast-enhanced abdominal spectral CT with a half contrast dose: a matched-pair comparison with a 120 kVp protocol

BJR|Open ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 20200006
Author(s):  
Daisuke Sakabe ◽  
Takeshi Nakaura ◽  
Seitaro Oda ◽  
Masafumi Kidoh ◽  
Daisuke Utsunomiya ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Renal Dysfunction ◽  
Organ Dose ◽  
Matched Pair ◽  
Spectral Ct ◽  
Abdominal Ct ◽  
Organ Doses ◽  
Imaging Protocol ◽  
Contrast Enhanced ◽  
Enhanced Ct

Objectives: To compare the estimated radiation dose of 50% reduced iodine contrast medium (halfCM) for virtual monochromatic images (VMIs) with that of standard CM (stdCM) with a 120 kVp imaging protocol for contrast-enhanced CT (CECT). Methods: We enrolled 30 adults with renal dysfunction who underwent abdominal CT with halfCM for spectral CT. As controls, 30 matched patients without renal dysfunction using stdCM were also enrolled. CT images were reconstructed with the VMIs at 55 keV with halfCM and 120 kVp images with stdCM and halfCM. The Monte-Carlo simulation tool was used to simulate the radiation dose. The organ doses were normalized to CTDIvol for the liver, pancreas, spleen, and kidneys and measured between halfCM and stdCM protocols. Results: For the arterial phase, the mean organ doses normalized to CTDIvol for stdCM and halfCM were 1.22 and 1.29 for the liver, 1.50 and 1.35 for the spleen, 1.75 and 1.51 for the pancreas, and 1.89 and 1.53 for the kidneys. As compared with non-enhanced CT, the average increase in the organ dose was significantly lower for halfCM (13.8% ± 14.3 and 26.7% ± 16.7) than for stdCM (31.0% ± 14.3 and 38.5% ± 14.8) during the hepatic arterial and portal venous phases (p < 0.01). Conclusion: As compared with stdCM with the 120 kVp imaging protocol, a 50% reduction in CM with VMIs with the 55 keV protocol allowed for a substantial reduction of the average organ dose of iodine CM while maintaining the iodine CT number for CECT. Advances in knowledge: This study provides that the halfCM protocol for abdominal CT with a dual-layer-dual-energy CT can significantly reduce the increase in the average organ dose for non-enhanced CT as compared with the standard CM protocol.

scholarly journals Liver fibrosis staging by deep learning: a visual-based explanation of diagnostic decisions of the model

2021 ◽  
Author(s):  
Yunchao Yin ◽  
Derya Yakar ◽  
Rudi A. J. O. Dierckx ◽  
Kim B. Mouridsen ◽  
Thomas C. Kwee ◽  
...  
Keyword(s):  
Deep Learning ◽  
Liver Fibrosis ◽  
Liver Parenchyma ◽  
Ct Images ◽  
Fibrosis Stage ◽  
Contrast Enhanced Ct ◽  
Contrast Enhanced ◽  
Enhanced Ct ◽  
Liver Surface ◽  
Fibrosis Staging

Abstract Objectives Deep learning has been proven to be able to stage liver fibrosis based on contrast-enhanced CT images. However, until now, the algorithm is used as a black box and lacks transparency. This study aimed to provide a visual-based explanation of the diagnostic decisions made by deep learning. Methods The liver fibrosis staging network (LFS network) was developed at contrast-enhanced CT images in the portal venous phase in 252 patients with histologically proven liver fibrosis stage. To give a visual explanation of the diagnostic decisions made by the LFS network, Gradient-weighted Class Activation Mapping (Grad-cam) was used to produce location maps indicating where the LFS network focuses on when predicting liver fibrosis stage. Results The LFS network had areas under the receiver operating characteristic curve of 0.92, 0.89, and 0.88 for staging significant fibrosis (F2–F4), advanced fibrosis (F3–F4), and cirrhosis (F4), respectively, on the test set. The location maps indicated that the LFS network had more focus on the liver surface in patients without liver fibrosis (F0), while it focused more on the parenchyma of the liver and spleen in case of cirrhosis (F4). Conclusions Deep learning methods are able to exploit CT-based information from the liver surface, liver parenchyma, and extrahepatic information to predict liver fibrosis stage. Therefore, we suggest using the entire upper abdomen on CT images when developing deep learning–based liver fibrosis staging algorithms. Key Points • Deep learning algorithms can stage liver fibrosis using contrast-enhanced CT images, but the algorithm is still used as a black box and lacks transparency. • Location maps produced by Gradient-weighted Class Activation Mapping can indicate the focus of the liver fibrosis staging network. • Deep learning methods use CT-based information from the liver surface, liver parenchyma, and extrahepatic information to predict liver fibrosis stage.

The effect of dynamic wedge angle in breast cancer's absorbed radiation dose

2020 ◽  
Author(s):  
Nurul Fitriyah ◽  
Rahmatul Izza Nur Amalia ◽  
Bambang Haris Suhartono ◽  
Suryani Dyah Astuti
Keyword(s):  
Radiation Dose ◽  
Wedge Angle ◽  
Dynamic Wedge ◽  
Absorbed Radiation Dose
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