Iodine-based Contrast Research Articles

Contrast-enhanced dual-energy mammography: a promising new imaging tool in breast cancer detection.

Contrast-enhanced dual-energy mammography (CEDM) is a promising new breast imaging tool for breast cancer detection. In CEDM, an iodine-based contrast agent is intravenously administered and subsequently, dual-energy mammography is performed. This results in a set of images containing both a regular mammogram and an image that contains contrast enhancement information. Preliminary studies have indicated that CEDM is superior to conventional mammography and might even match the diagnostic performance of breast MRI. In this review, the imaging technique, protocol and patient handling of CEDM is presented. Furthermore, an overview of current results on CEDM and potential future indications are outlined.

Lactobionic Acid-Modified Dendrimer-Entrapped Gold Nanoparticles for Targeted Computed Tomography Imaging of Human Hepatocellular Carcinoma

Development of novel nanomaterial-based contrast agents for targeted computed tomography (CT) imaging of tumors still remains a great challenge. Here we describe a novel approach to fabricating lactobionic acid (LA)-modified dendrimer-entrapped gold nanoparticles (LA-Au DENPs) for in vitro and in vivo targeted CT imaging of human hepatocellular carcinoma. In this study, amine-terminated poly(amidoamine) dendrimers of generation 5 pre-modified with fluorescein isothiocyanate and poly(ethylene glycol)-linked LA were employed as templates to form Au nanoparticles. The remaining dendrimer terminal amines were subjected to an acetylation reaction to form LA-Au DENPs. The prepared LA-Au DENPs were characterized via different methods. Our results reveal that the multifunctional Au DENPs with a Au core size of 2.7 nm have good stability under different pH (5-8) and temperature (4-50 °C) conditions and in different aqueous media, and are noncytotoxic to normal cells but cytotoxic to the targeted hepatocarcinoma cells in the given concentration range. In vitro flow cytometry data show that the LA-Au DENPs can be specifically uptaken by a model hepatocarcinoma cell line overexpressing asialoglycoprotein receptors through an active receptor-mediated targeting pathway. Importantly, the LA-Au DENPs can be used as a highly effective nanoprobe for specific CT imaging of hepatocarcinoma cells in vitro and the xenoplanted tumor model in vivo. The developed LA-Au DENPs with X-ray attenuation property greater than clinically employed iodine-based CT contrast agents hold a great promise to be used as a nanoprobe for targeted CT imaging of human hepatocellular carcinoma.

The utility of routine postoperative upper gastrointestinal swallow studies following laparoscopic sleeve gastrectomy.

Laparoscopic sleeve gastrectomy (LSG) has grown in popularity in recent years for the treatment of morbid obesity. Controversy exists regarding the usefulness of upper gastrointestinal (UGI) swallow studies on the first postoperative day in detecting possible complications. The aim of our study was to determine the efficacy and cost benefit of routine UGI studies on the first postoperative day following LSG. We retrospectively reviewed the hospital's records to identify patients who underwent LSG between January 2012 and June 2013. All patients had iodine-based contrast swallow study on the first postoperative day. Reports from all imaging studies and medical files were retrospectively reviewed, and complications were recorded. The Institutional Review Board waived the requirement for informed consent. During the study period, 722 patients underwent LSG. Mean BMI was 43 kg/m(2) (range 25-70). Of the 722 UGI studies, 721 were normal. The 1 abnormal study showed complete obstruction due to an incarcerated hiatal hernia. Five patients presented with a leak (0.7%). UGI swallow studies failed to detect any of the leaks resulting in a sensitivity of 0%. All leaks were apparent on computed tomography (CT) scans on postoperative days 2, 5, 7, 23, and 90. The total cost of the UGI swallow studies was $180,500. Performing routine UGI studies on the first postoperative day following LSG is clearly not cost beneficial. UGI contrast studies are not efficient to screen for suture line leaks. We recommend obtaining a CT scan when there is clinical suspicion for a complication.

Fabrication and characterization of composite hydrogel particles with x-ray attenuating payloads

This paper reports the fabrication and characterization of composite hydrogel particles composed of poly(ethylene glycol) diacrylate (PEG-DA)-based hydrogels and x-ray attenuating payloads. The top–down fabrication method employed herein is demonstrated to yield composite hydrogel particles of varying size and shape for use as computed tomography (CT) imaging contrast agents. Characterization of the materials properties of the PEG-DA hydrogels was undertaken, demonstrating tunable mechanical properties of composite hydrogels based on hydrogel composition and UV cross-linking time. Analyses of the leakage rates of a conventional iodine-based small molecular contrast agent as well as a nanoparticulate x-ray attenuating material from the PEG-DA hydrogels were undertaken. In contradistinction to clinically available iodinated CT contrast agents, as well as recently developed nanoparticulate CT contrast agents, the approach presented herein yields an engineering flexibility to the design of CT contrast agents which may be leveraged to optimize this class of agents to a wide array of specific imaging and sensing applications.

3.9. Value of minimally invasive, whole body postmortem CT angiography in the assessment of massive haemoptysis

Objective Since the demise of advanced pulmonary tuberculosis in our community, fatal haemoptysis is unusual mostly seen after penetrating trauma including surgical procedures and advanced malignancy. Detection of the responsible vessel at autopsy can be technically difficult. Postmortem CT angiography (PMCTA) is routinely used at our institution to identify sites of bleeding. Material and methods 170 PMCTA procedures have been performed since 2010 utilizing a modified Bern technique including a solution of iodine-based radiographic contrast and PEG 200, infused via the femoral artery using a Dodge ® embalming pump and dual energy CT imaging. 10 cases of massive haemoptysis were identified. PMCTA images were reviewed and correlated with autopsy findings. Results Of the 10 cases, 4 were ultimately shown at autopsy to be due to advanced malignancy and 6 traumatic (5 of these iatrogenic). PMCTA was able to detect a bleeding point in 9 of 10 cases, being negative in a case of post CT-guided lung biopsy. In one case, the PMCTA detected a bleeding point in the trachea following oesophagogastrectomy for caustic ingestion. At autopsy the pathologist was unable to detect any specific bleeding vessel. Conclusion PMCTA as applied at our institution is useful for identifying bleeding points in massive haemoptysis. Intervention to the body is remote to the site of pathology (avoiding artefact) and the whole body vascular opacification allows assessment of all possible responsible vessels including sites not necessarily suspected prior to autopsy. Localizing disrupted vessels prior to autopsy allows the pathologist to focus their dissection.

Fluctuations in eGFR in relation to unenhanced and enhanced MRI and CT outpatients

ObjectiveTo study fluctuations in estimated glomerular filtration rate (eGFR) in relation to contrast medium (CM) enhanced magnetic resonance imaging (MRI) and computed tomography (CT) compared to control groups in outpatients. Materials and methodseGFR was determined right before the imaging procedure and three days later at the department or at the patient's home. The iodine-based and gadolinium-based contrast media were the same as used for all other examinations at the department. ResultsA total of 716 patients completed the study. There was a statistically significant, but not clinically relevant rise in eGFR after three days in all four groups. The average eGFR variation was 4.8ml/min/1.73m2. There were large variations in eGFR between the two measurements in 45.8% of the patients as they had a change greater than ±10ml/min/1.73m2. Only three patients fulfilled the contrast-induced nephropathy (CIN) requirement when the definition s-creatinine ≥44μmol/l (0.5mg/dl) was used. ConclusionseGFR in outpatients undergoing MRI or CT did vary independently of whether the patient received contrast or not. The findings probably reflect the natural variations in s-creatinine levels. This should be taken into consideration when CIN is studied.

Nephropathy after administration of iso-osmolar and low-osmolar contrast media: Evidence from a network meta-analysis

Background/objectivesContrast-induced nephropathy (CIN) may be a severe complication to the administration of iodine-based contrast media for diagnostic or interventional procedure using radiation exposure. Whether there is a difference in nephrotoxic potential between the various agents is uncertain. We aimed to perform a systematic review and network meta-analysis of randomized trials on iodine-based contrast agents. MethodsRandomized trials of low-osmolar or iso-osmolar contrast media were searched in CENTRAL, Google Scholar, MEDLINE/PubMed, and Scopus. Risk of CIN was appraised within a hierarchical Bayesian model computing absolute rates (AR) and odds ratios (OR) with 95% credibility intervals, and probability of being best (Pbest) for each agent. ResultsA total of 42 trials (10048 patients) were included focusing on 7 different iodine-based contrast media. Risk of CIN was similarly low with iodixanol (AR=5.7% [2.2%–13.9%], Pbest=18.8%), iomeprol (AR=6.0% [2.2%–15.4%], Pbest=24.8%), iopamidol (AR=6.1% [2.2%–15.5%], Pbest=21.5%), and ioversol (AR=6.0% [2.1%–16.4%], Pbest=31.3%). Conversely, CIN was twice as common with iohexol (AR=11.2% [4.1%–29.5%], Pbest=0.1%) and ioxaglate (AR=11.0% [4.0%–26.9%], Pbest<0.1%), with both proving less safe than iodixanol (respectively OR=2.18 [1.22–3.92] and 2.05 [1.26–3.29]), iomeprol (OR=2.08 [1.04–4.17] and 1.96 [1.06–3.48]) and iopamidol (OR=2.04 [1.15–3.85] and 1.92 [1.06–3.45]). Data on iopromide were less conclusive (AR=6.9% [2.6%–17.1%], Pbest=3.6%). ConclusionsIodixanol, iomeprol, iopamidol and ioversol are iodine-based contrast media with a similar renal safety profile. Iohexol and ioxaglate have a poorer renal safety profile, whereas further data may be required on iopromide.

The studies on highly concentrated complex dispersions of gold nanoparticles and temperature-sensitive nanogels and their application as new blood-vessel-embolic materials with high-resolution angiography.

Recently temperature sensitive polymers have been developed as novel embolization materials. However, their flowability and embolization have been seriously impacted by iodine-based X-ray contrast agents. In order to resolve the drawbacks of these contrast agents, highly concentrated complex (HCC) dispersions of gold nanoparticles (GNPs) with p(N-isopropylacrylamide-co-butyl methylacrylate) (PIB) nanogels were developed as new blood-vessel-embolic materials with high-resolution angiography. Although GNPs have better X-ray attenuation than iodinated compounds, their poor dispersion stability limits their application in digital subtraction angiography (DSA). HCC dispersions show excellent X-ray attenuation ability which is 2.6 times higher than Omnipaque at 0.31 mol L-1. This can be attributed to the fact that the sol-gel transition of nanogel dispersions improves the colloid stability of GNPs. In the two sol-gel transition temperatures (Tg-s and T's-g) of nanogel dispersions, GNPs have no influence on T's-g, and a great influence on Tg-s. The in vivo experimental data indicate that HCC dispersions show high angiographic ability and good blood-vessel embolization, and can be used for postoperative examination for long periods owing to the entrapment of GNPs into the embolic sites. The HCC dispersions have potential to be developed as new blood-vessel-embolic materials with high-resolution angiography.

Clinical features of delayed contrast media hypersensitivity

Purpose: Delayed hypersensitivity reaction can occur in a couple of hours to several days after injection of iodine-based contrast media (ICM). ICM-related delayed type hypersensitivity is not common but increasing as rapid growth of ICM use. Nevertheless, objective data on delayed type hypersensitivity are still scarce worldwide including Korea. This study was performed to investigate the clinical features of ICM-induced delayed hypersensitivity in Korean patients. Methods: We retrospectively reviewed the electronic medical records of patients diagnosed with delayed hypersensitivity to ICM from January 2009 to December 2012 at Seoul National University Hospital and analyzed the data to identify the clinical characteristics of these patients. Results: A total of 44 cases were diagnosed as delayed-type hypersensitivity to ICM. The mean age was 54 years, and 70.5% were female. The mean number of previous ICM exposure was 3.8, and skin reactions were the most common symptoms. In 45% of patients, hypersensitivity reaction developed on the first exposure to ICM. Among the 27 patients exposed to ICM again, hypersensitivity reactions recurred in only 4 patients (14.8%). There was no difference of recurrence rate according to the use of premedication or the change in ICM. Conclusion: In this study, we observed a female predominance and a low recurrence rate in delayed hypersensitivity to ICM. Premedication and ICM change was not effective in preventing recurrence of delayed type reactions. (Allergy Asthma Respir Dis 2014;2:352-357)

State of the Heart: CMR in Coronary Artery Disease

The application of magnetic resonance imaging (MRI) in evaluating the heart and its plethora of diseases has grown over the years. Abundant research and advancements in this modality had been made, largely due to the perceived benefits of MRI. These accepted advantages of MRI include absence of ionizing radiation, reproducible technique and does not require iodine-based contrast media. It had even been touted as the ‘one-stop shop’ for cardiac imaging. Cardiac magnetic resonance (CMR) has the ability to assess the heart comprehensively, examining cardiac morphology, ventricular function, perfusion, myocardial viability, as well as delineation and quantification of tissue constituents. Other benefits lie in the intrinsic properties of MRI which provide high temporal and spatial resolution, superb tissue contrast and possibility of imaging in any plane. In view of these superior advantages of CMR, it is currently the modality of choice in a number of cardiac diseases.

Quantitative and qualitative bowel analysis using mannitol, water and iodine-based endoluminal contrast agent on 64-row detector CT

Objective:To assess the performance of mannitol as a luminal contrast as compared to water and positive contrast in evaluation of bowel on multidetector computed tomography (MDCT).Materials and Methods:Three hundred patients were randomly selected for this study and were divided equally into three groups. Each subject received 1500 ml of oral contrast. Group 1 received 3% mannitol in water, group 2 received diluted iodinated positive contrast, and group 3 received plain water without additives. Qualitative and quantitative analysis for distension, fold visibility, and overall image quality were analyzed by actual diameter measurement and point scale system at different bowel levels. One-way analysis of variance (ANOVA) followed by Tukey's HSD Post-hoc test and Pearson's Chi-square (exact test) test were applied.Results:Group 1 showed better results for small bowel distension, intraluminal homogeneity, and visibility of mucosal folds on quantitative and qualitative analysis with statistically significant P value (P<0.001). The ileo-caecal junction distension and mural feature visibility was better with mannitol (P < 0.001). No significant difference in distension of stomach and duodenum was found between the three groups.Conclusion:Mannitol as endoluminal contrast increases the diagnostic accuracy of the investigative studies in comparison to water and iodine-based contrast by producing significantly better bowel distension and visibility of mural features with improved image quality without additional adverse effects.

Evaluation of a method for improving the detection of hepatocellular carcinoma

To improve the detection of liver lesions in patients with hepatocellular carcinoma (HCC) via an iodine contrast enhancement tool. Thirty-two patients with clinically proven HCCs underwent imaging with a three-phase protocol on a 256-slice MDCT. The contrast enhancement in the reconstructed slices was improved via a post-processing tool. Mean image noise was measured in four different regions: liver lesion, healthy liver, subcutaneous fat and bone. For each image set the image noise and contrast-to-noise ratio (CNR) were assessed. For subjective image assessment, four experienced radiologists evaluated the diagnostic quality. While employing the post-processing algorithm, CNR between the liver lesion and healthy liver tissue improves significantly by a factor of 1.78 (CNRwithout vC = 2.30 ± 1.92/CNRwith vC = 4.11 ± 3.05) (P* = 0.01). All results could be achieved without a strengthening of artefacts; mean HU values of subcutaneous fat and bone did not significantly change. Subjective image analysis illustrated a significant improvement when employing post-processing for clinically relevant criteria such as diagnostic confidence. With post-processing we see a significantly improved detection of arterial uptake in hepatic lesions compared with non-processed data. The improvement in CNR was confirmed by subjective image assessment for small lesions and for lesions with limited uptake. • Enhancement with iodine-based contrast agents is an essential part of CT. • A new post-processing tool significantly improves the diagnostics of hepatocellular carcinoma. • It also improves detection of small lesions with limited iodine uptake.

Dose optimization in cardiac x‐ray imaging

The aim of this research was to optimize x-ray image quality to dose ratios in the cardiac catheterization laboratory. This study examined independently the effects of peak x-ray tube voltage (kVp), copper (Cu), and gadolinium (Gd) x-ray beam filtration on the image quality to radiation dose balance for adult patient sizes. Image sequences of polymethyl methacrylate (PMMA) phantoms representing two adult patient sizes were captured using a modern flat panel detector based x-ray imaging system. Tin and copper test details were used to simulate iodine-based contrast medium and stents∕guide wires respectively, which are used in clinical procedures. Noise measurement for a flat field image and test detail contrast were used to calculate the contrast to noise ratio (CNR). Entrance surface dose (ESD) and effective dose measurements were obtained to calculate the figure of merit (FOM), CNR(2)∕dose. This FOM determined the dose efficiency of x-ray spectra investigated. Images were captured with 0.0, 0.1, 0.25, 0.4, and 0.9 mm Cu filtration and with a range of gadolinium oxysulphide (Gd2O2S) filtration. Optimum x-ray spectra were the same for the tin and copper test details. Lower peak tube voltages were generally favored. For the 20 cm phantom, using 2 Lanex Fast Back Gd2O2S screens as x-ray filtration at 65 kVp provided the highest FOM considering ESD and effective dose. Considering ESD, this FOM was only marginally larger than that from using 0.4 mm Cu at 65 kVp. For the 30 cm phantom, using 0.25 mm copper filtration at 80 kVp was most optimal; considering effective dose the FOM was highest with no filtration at 65 kVp. These settings, adjusted for x-ray tube loading limits and clinically acceptable image quality, should provide a useful option for optimizing patient dose to image quality in cardiac x-ray imaging. The same optimal x-ray beam spectra were found for both the tin and copper details, suggesting that iodine contrast based imaging and visualization of interventional devices could potentially be optimized for dose using similar x-ray beam spectra.

Is Sucralose Ingestion Acceptable Before 18F-FDG PET/CT Imaging?

A 2009 international survey of 128 PET/CT technologists revealed that 58% of them administered oral contrast agents as part of their protocol for “some or most patients” ([1][1]). Among those using oral contrast agents, iodine-based contrast material was administered 35% of the time. An

Direct visualization of gastrointestinal tract with lanthanide-doped BaYbF5 upconversion nanoprobes

Nanoparticulate contrast agents have attracted a great deal of attention along with the rapid development of modern medicine. Here, a binary contrast agent based on PAA modified BaYbF5:Tm nanoparticles for direct visualization of gastrointestinal (GI) tract has been designed and developed via a one-pot solvothermal route. By taking advantages of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of these well-designed nanoparticles, their feasibility as a multi-modal contrast agent for GI tract was intensively investigated. Significant enhancement of contrast efficacy relative to clinical barium meal and iodine-based contrast agent was evaluated via X-ray imaging and CT imaging in vivo. By doping Tm3+ ions into these nanoprobes, in vivo NIR–NIR imaging was then demonstrated. Unlike some invasive imaging modalities, non-invasive imaging strategy including X-ray imaging, CT imaging, and UCL imaging for GI tract could extremely reduce the painlessness to patients, effectively facilitate imaging procedure, as well as rationality economize diagnostic time. Critical to clinical applications, long-term toxicity of our contrast agent was additionally investigated in detail, indicating their overall safety. Based on our results, PAA-BaYbF5:Tm nanoparticles were the excellent multi-modal contrast agent to integrate X-ray imaging, CT imaging, and UCL imaging for direct visualization of GI tract with low systemic toxicity.

Lack of functional patency of the lamina terminalis after fenestration following clipping of anterior circulation aneurysms

Fenestration of the lamina terminalis (FLT) during aneurysm surgery for subarachnoid hemorrhage can, in theory, improve CSF circulation from the lateral and third ventricles to the cortical subarachnoid space, which may, in turn, decrease the incidence of hydrocephalus and vasospasm. However, the actual effects of FLT on CSF circulation have been difficult to determine, due to confounding factors. In addition, it is unclear whether the lamina terminalis remains functionally patent when the brain resumes its normal position. The goal of this study was to assess the functional patency of the fenestrated lamina terminalis in patients who underwent surgery for ruptured aneurysms. This prospective study included 15 patients who underwent surgical clipping of ruptured anterior circulation aneurysms, with FLT performed during surgery. On postoperative Day 1, the external ventricular drain of each patient was closed, and 1 ml of Omnipaque 300, an iodine based contrast agent, was injected intraventricularly, accompanied by cranial maneuvering designed to position the contrast agent adjacent to the lamina terminalis. Three to 5 minutes after cranial maneuvering, the flow of contrast agent into the basal cisterns was assessed with CT imaging. Flow was verified by an increase in Hounsfield units in a prespecified "region of interest" within the basal cisterns on the CT scan. This procedure was performed using a standardized protocol designed in consultation with the Department of Radiology and approved by the institutional review board. One patient who underwent endoscopic third ventriculostomy was recruited as a positive control to validate the technique, and 1 patient who underwent aneurysm clipping but not FLT was recruited as a negative control. Seventeen patients consented to study participation. In the 15 patients who underwent aneurysm clipping and FLT, and the negative control patient who underwent aneurysm clipping but not FLT, the contrast agent followed the normal ventricular pathway from the lateral ventricles into the fourth ventricle, and did not appear in the basal cisterns. In the positive control patient, the contrast agent robustly and immediately filled the basal cisterns. Fenestration of the lamina terminalis did not result in functional patency of the lamina terminalis when performed as part of surgical clipping for ruptured aneurysms.

Gold Nanoparticles Provide Bright Long-Lasting Vascular Contrast for CT Imaging

Iodinated contrast agent for CT has a short half-life in the vasculature. As the field of interventional procedures expands, a more durable contrast agent would be highly useful. Our study investigated whether gold nanoparticles are feasible as a long-lasting vascular contrast agent for CT. Gold nanoparticles were synthesized by a modified Turkevich method, coated with methoxy-polyethylene glycol-thiol chains, and compared with an iodine-based contrast agent used in mice. Contrast agents were imaged in tubes by CT at 40, 60, and 140 kVp and then were tested in vivo by tail vein injection. Nine mice received gold nanoparticles, two received iodine-based contrast agent, and one received saline. CT of mice was performed at 60 kVp immediately, 6 hours, and 24 hours after injection. In an isolated form in tubes, gold nanoparticles had greater radiographic density than did iodine-based contrast agent at 40 kVp and were comparable at the other CT voltages. In mice, gold nanoparticles provided bright contrast enhancement that enabled clear visualization of the abdominal aorta and renal arteries, which could not be distinguished without contrast agent. This persisted up to 24 hours, which was the last time point assessed. Contrast enhancement of the vasculature by iodine-based contrast agent was present immediately after injection but had disappeared by 6 hours. Gold nanoparticles can provide clear and durable contrast enhancement of the vasculature even at 24 hours. These findings merit further study of gold nanoparticles for their potential as a contrast agent in CT and CT-guided interventional procedures.

Optimal management of acute nonrenal adverse reactions to iodine-based contrast media

Acute adverse reactions to iodine-based contrast media occur within 60 minutes of administration. The reactions range from mild (flushing, arm pain, nausea/vomiting, headache) to moderate (bronchospasm, hypotension), and severe (cardiovascular collapse, laryngeal edema, convulsions, arrhythmias). Most acute adverse reactions occur in an unpredictable manner. Use of the older group of ionic iodine-based contrast agents increases the risk of acute adverse reactions. Other risk factors include previous reactions to contrast media, asthma, and allergic conditions. The exact pathophysiology of the acute adverse reactions is unknown, but some of the reactions are pseudoallergic mimicking type 1 allergic reactions. As antibodies against contrast media have not been consistently demonstrated, the reactions are, in most cases, not truly allergic in nature. Most of the severe and fatal adverse reactions occur within the first 20 minutes after injection. Thus, it is important that patients are observed in the radiology department during this period. The radiologist should be near the room where contrast media is administered, and be ready to treat any acute nonrenal adverse reaction. Appropriate drugs and resuscitation equipment should be in/near the room where the contrast media is administered. The important first-line management of acute adverse reactions includes the establishment of an adequate airway, oxygen supplementation by mask, intravenous fluid administration, and measurement of blood pressure and heart rate. When severe anaphylactoid reactions occur, adrenaline should be given intramuscularly. Only one concentration of adrenaline (1:1000-1 mg/mL) should be available in the radiology department to avoid dosing errors in stressful acute settings. Resuscitation team specialists should be the only ones giving intravenous adrenaline. It is important that all radiologists maintain the capability of performing first-line treatment of acute adverse reactions

WE-G-103-01: Dual-Energy Temporal Study of Contrast-Enhanced Digital Mammography in 20 Patients: The Use of a Pixel-By-Pixel Weighting Formalism for the Subtraction

Purpose: To study the possible correlation between iodine uptake in contrast-enhanced digital mammography images and microvessel density (MVD) in breast lesions. Methods: 20 BIRADS 4–5 patients were included. Mask images were acquired with low-and high-energy spectra from a SenographeDS. Iodine-based contrast medium (CM) was mechanically injected and high-energy CM images acquired between 1 and 5 minutes after injection. A biopsy was obtained after the images and specific biomarkers for newly-formed blood and lymphatic microvessels were applied; MVD was later evaluated in microscope fields. The subtraction combined dual-energy and temporal modalities. LE masks were subtracted from weighted CM images, and weight factor was a matrix obtained from the masks, containing pixel-by-pixel anatomical and radiological information. Iodine uptake in subtracted temporal series was quantified by contrast between lesion and normal glandular tissue. Alternative metrics for contrast quantification were evaluated. Contrast was transformed into iodine mass-thickness using calibrated samples. Results: 12 cases were malignant and 8, benign. The matrix-based subtraction formalism severely reduced anatomic noise in resulting images, compared with alternative techniques based on mean pixel values within regions-of-interest. Five types of time-intensity curves were identified, qualitatively similar to MRI. If iodine uptake in the lesion was evaluated, most frequent curve was plateau type, for cancer and malignant cases. The normalized Weber contrast indicated a frequency distribution with zero-contrast cases for benign lesions and most-frequent curve type washout for cancer. No correlation was found between contrast indicators and MVD. Blood and lymphatic MVD were correlated (r=0.94, p<0.05) and mean blood MVD values in cancer were about twice those in benign cases. Conclusion: This subtraction formalism, previously validated in non-homogeneous phantom images, adds quantitative features to the resulting clinical images. The statistical distribution of contrast curves for cancer and benign cases seems to be the most relevant parameter with a possible diagnostic value. Funding: DGAPA-UNAM Grants 102610 and 105813; Conacyt Grant Salud 2009-01-112374. No conflict of interest.

Association between the use of computed tomography scans using iodine-based contrast medium and the development of subsequent hyperthyroidism

Association between the use of computed tomography scans using iodine-based contrast medium and the development of subsequent hyperthyroidism