Total Injection Time Research Articles

Should the dose of contrast medium be determined solely on the basis of body weight regardless of the patient’s sex?

The aim of this study was to evaluate prospectively the difference in contrast enhancement of liver parenchyma between male and female subjects when the total amount of contrast material is determined by the total body weight (TBW). Computed tomography of the abdomen was performed with a total amount of iodine of 597 ± 3.9 mg I/kg (mean ± SD) over a mean ± SD total injection time of 30 ± 0.26 s. Postcontrast attenuation during the portal venous phase was measured in the liver parenchyma, portal vein, and aorta. These values were summed for each and compared to those obtained before contrast injection. A total of 565 consecutive patients without a history of underlying liver/heart disease, including 297 male and 268 female subjects (age 16-92 years, mean 67 years) were scanned and analyzed using a two-tailed t-test. The difference between precontrast and the portal venous phase in the male subjects was 315.4 ± 40.5 HU (mean ± SD), and that in female subjects was 358.6 ± 44.8 HU. This difference was statistically significant (P < 0.0001). The contrast enhancement in females was 13.7% higher than that in males when the amount of iodine administered was based on the TBW. The difference can presumably be attributed to the difference in fat and muscle components. This result suggests that the amount of contrast material used in females should be reduced according to this difference.

Experimental performance evaluation of multi‐echo ICNE pulse sequence in magnetic resonance electrical impedance tomography

Latest experimental results in magnetic resonance electrical impedance tomography (MREIT) demonstrated high-resolution in vivo conductivity imaging of animal and human subjects using imaging currents of 5 to 9 mA. Externally injected imaging currents induce magnetic flux density distributions, which are affected by a conductivity distribution. Since we extract the induced magnetic flux density images from MR phase images, it is essential to reduce noise in the phase images. In vivo human and disease model animal experiments require reduction of imaging current amplitudes and scan times. In this article, we investigate a multi-echo based MREIT pulse sequence where we utilize a remaining time after the first echo within one TR to obtain more echo signals. It also allows us to prolong the total current injection time. From phantom and animal imaging experiments, we found that this method significantly reduces the noise level in measured magnetic flux density images. We describe experimental validation of the multi-echo sequence by comparing its performance with a single-echo method using 3 mA imaging currents. The proposed method will be advantageous for an imaging region with long T2 values such as the brain and knee. Depending on T2 values, we suggest using two or three echoes in future experimental studies.

Letter to the Editor re: Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

Sir, We read with great interest the article by Lenhart and colleagues recently published in European Radiology and reporting effectiveness of selective arterial embolisation using Onyx® in patients with acute gastrointestinal bleeding [1]. We have several comments. First of all, we would like to congratulate the authors for their study which represents the first series to date reporting results on arterial embolotherapy with Onyx® as an embolic agent in the gastrointestinal tract. Until now, the only available data on the use of this embolic material for peripheral applications came from case reports. Indeed, Onyx® is a new liquid embolic agent composed of ethylene-vinyl alcohol copolymer dissolved in dimethyl sulphoxide (DMSO), with emerging applications in neurovascular procedures, predominantly embolisation of cerebral aneurysms and arteriovenous malformations [2]. The main advantages of Onyx® are its nonadhesive properties, high radiopacity, and long solidification periods, which, compared with acrylic glues, make the embolisation procedure more controllable and predictable. However, the authors did not bring to attention several important disadvantageous characteristics of the use of Onyx®. First, DMSO can cause severe vasospasm if injected rapidly. This is most likely to occur early in the procedure and can be avoided by using no more than 0.2 ml of DMSO in the first minute of injection. Even if the authors reported a total injection time of DMSO and Onyx® of 10 min on average for their procedure, in our experience, the duration of injection is often much longer and varies depending on the amount of Onyx® used. Secondly, DMSO is volatile and is excreted via respiration and sweat. This has a typical smell not unlike that of diabetic ketoacidosis and may last a few days. The patient and ward staff should be warned to expect this. Lastly, the use of Onyx® has cost implications as it is much more expensive than alternative embolic materials and it requires specific DMSO-compatible microcatheters. The prohibitive costs of using Onyx® have led to its restricted use in neuroradiology in most of the institutions around the world. In conclusion, we think this embolic agent is very promising but the important cost aspect needs to be borne in mind when there are other cheaper alternatives that would be as effective and faster when used on an emergency basis.

Usefulness of diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging in the diagnosis of prostate transition-zone cancer

Conventional T2-weighted (T2-WI) magnetic resonance imaging (MRI) has poor sensitivity for prostate transition-zone (TZ) cancer detection. To retrospectively evaluate the clinical value of diffusion-weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) in combination with T2-WI for the diagnosis of TZ cancer. Twenty-six TZ cancers in 23 patients with at least one tumor (tumor size >10 mm) located predominantly in the TZ were included in the study. Sixteen peripheral-zone (PZ) cancers in 12 patients with PZ cancer but without TZ cancer (control group) were selected by step-section pathologic maps. All patients underwent MRI and radical prostatectomy. MRI was obtained by a 1.5T superconducting system with a phased-array coil. Imaging sequences were T2-WI with fat saturation (FST2-WI), DW-MRI (single-shot echoplanar image, b=0 and 1000 s/mm(2), apparent diffusion coefficient [ADC] map findings), and DCE-MRI (3D fast spoiled gradient recalled [SPGR], contrast medium [0.2 mmol/kg], total injection time 5 s, image acquisition 30, 60, and 90 s). Sensitivity, specificity, accuracy, and positive predictive value (PPV) for the diagnosis of TZ cancer were evaluated in four protocols: A) FST2-WI alone, B) FST2-WI plus DW-MRI, C) FST2-WI plus DCE-MRI, D) FST2-WI plus DW-MRI plus DCE-MRI. Sensitivity, specificity, accuracy, and PPV in protocol A (FST2-WI alone) were 61.5%, 68.8%, 64.3%, and 76.2%, respectively. FST2-WI plus DW-MRI (protocol B) improved the sensitivity, specificity, accuracy, and PPV. In FST2-WI plus DW-MRI plus DCE-MRI (protocol D), the number of true-negative lesions increased and false-positive lesions decreased, and the sensitivity, specificity, accuracy, and PPV were 69.2%, 93.8%, 78.6%, and 94.7%, respectively. There was a significant difference between protocols A and D (P<0.05). Adding DW-MRI to FST2-WI in the diagnosis of prostate TZ cancer increased the diagnostic accuracy. The addition of DCE-MRI may be an option to improve the specificity and PPV of diagnosing TZ cancer with FST2-WI and DW-MRI.

In-Plane형 마이크로니들의 미세사출공정해석

Micro injection molding analysis for microneedle fabrication was performed in the present study. The dimensions of width and thickness for in-plane microneedle are <TEX>$600{\mu}m$</TEX>, <TEX>$500{\mu}m$</TEX>, respectively. A delivery system based on guidelines for traditional injection molding was designed for four-cavities molding system. To investigate the effects of processing conditions in the mirconeedle fabrication, injection molding analysis using commercial code was performed. It was shown that the total injection time has a significant effect on the fabrication of in-plane microneedles.

Computer-controlled delivery versus syringe delivery of local anesthetic injections for therapeutic scaling and root planing

The authors conducted a study to compare administration of local anesthetic using a computer-controlled delivery device with an aspirating syringe for therapeutic scaling and root planing. The anterior middle superior alveolar, or AMSA, injection was compared with other maxillary injections. Twenty healthy adults with moderate periodontal disease participated in this single-blind crossover study. Subjects were evaluated by a trained examiner and were treated by experienced dental hygienists. Subjects provided written and verbal pain ratings via a visual analog scale, or VAS, and a verbal rating scale, or VRS. AMSA injections were compared with syringe-delivered injections--greater palatine, or GP, and nasopalatine, or NP, blocks, and anterior superior alveolar and middle superior alveolar injections--in maxillary quadrants. Bleeding and changes in attachment were evaluated after one month. VAS and VRS scores for AMSA were significantly lower for computer-controlled delivery when compared with NP injections and combined maxillary injections (VAS scores) and with GP and combined maxillary injections (VRS scores). Mean injection times were similar for both groups. Mean gains in attachment were equal, 0.19 millimeters for quadrants anesthetized using computer-controlled injections and 0.22 mm for syringe injections. Subjects reported having less pain with GP and NP injections delivered using the computer-controlled device, and total injection time was similar to that required for syringe injections. Both techniques provided adequate anesthesia for therapeutic scaling and root planing. Clinical Implications. The two anesthetic delivery techniques were therapeutically equivalent for mandibular injections, and the AMSA injection has clinically significant advantages for maxillary injections.

Organization of Chemically Activated Food Search Behavior in Procambarus clarkii Girard and Orconectes rusticus Girard Crayfishes

The feeding responses of decapod crustaceans to chemical stimuli have most often been evaluated in terms of one defining act, ignoring the organization of the behavior. To gain greater insight into foraging behavior, we considered the organization of food-search behavior in evaluating the responses of two species of crayfishes to a feeding stimulant. We also examined the effects of food deprivation on the behavioral organization and whether a behavioral dichotomy exists between food search and feeding behavior in these species. Individual crayfish of the species Procambarus clarkii and Orconectes rusticus were presented with infusions of a feeding stimulant consisting of a supernatant leachate of 100 ml water and 1 g of fish flakes. The stimulant was injected with a syringe and small-bore plastic infusion tubing into the center of a behavioral arena 25 cm square and 15 cm deep. Total injection time was 20 s. Experimental groups were presented with either the full-strength leachate (100%) or one of five dilutions: 75%, 50%, 25%, 10%, or 0% (controls) of full-strength. The feeding stimulant was presented either the day after the crayfish were fed or after one week of food deprivation. We analyzed three components of food-search behavior--detection, probing (near-field search), and locomotion (far-field, or distant, search)--recording the order of occurrence and the latency time to initiation for each behavior. When presented with the stimulus following regular feeding, both species responded to concentrations {ge}50% full-strength with probing behavior (near-field search) prior to locomotion, and to concentrations <50% full-strength with locomotion prior to, or even in the absence of, probing. Detection always occurred first. These results indicate that chemical stimuli preferentially activate distant food search in both species and that a behavioral dichotomy exists between food search and feeding behavior. One week of food deprivation had no effect on the organization of food-search behavior in P. clarkii; however, groups of unfed O. rusticus presented with 25% and 10% full-strength concentrations probed prior to locomotion, indicating a change in behavioral organization.

Composite Pd-Ag Particles in Aqueous Solution

published in Advance ACS Abstracts, May 15, 1994. 0022-3654/94/2098-62 12%04.50/0 palladium concentration was 1.2 X 10-4 M as determined by atomic emission spectroscopy. In the silver deposition experiments, the palladium solution was diluted by roughly a factor of 4. Experiments were also carried out to reduce Pd(I1) in the absence of the stabilizing PVS. Under these circumstances, the loss of reduced palladium was much greater than in the presence of PVS. This polymer is not removed by the treatment of the solution with Amberlite (in fact, when a pure PVS solution was treated with Amberlite, the conductivity actually increased, because the K+ ions of PVS were exchanged for free H+ ions). In order to coat the Pd colloids, two methods were used to reduce Ag+ ions. First, the radiolytic method was tried, which in many other cases has been quite useful for preparing concentric bimetallic particles. NaAg(CN)2 was added to the palladium colloid as well as 0.5 M propanol-2 and 0.1 M acetone. As described previously,4b exposure to y-rays leads to the formation of organic radicals that transfer electrons to the Pd particles. The Pd particles are polarized cathodically, and the stored electrons reduce the silver-cyano complexon thesurface of the Pd particles, which leads to a silver mantle. However, it was found that part of the radicals reduced the complexed silver ions directly in solution, the result being that individual silver particles were also formed. Second, formaldehyde was used as the reducing agent. When Ag+ ions are reduced by formaldehyde in the absence of colloidal palladium, an induction period of several minutes is observed. However, when Pd particles are present, the reduction occurs practically instantaneously and individual silver particles are not produced. This method was then applied in all experiments. In detail, the procedure was as follows: 2 X 10-4 M formaldehyde was added to 75 mL of Pd solution (at pH = 11). The solution was in a round flaskunder nitrogen, which had a side arm carrying a 1-cm optical cuvette and a septum. Several milliliters of deaerated AgC104 solution ( 5 X 10-5 to 2 X 10-3 M) was slowly injected (less than 1 mL per minute) under strong stirring. The total injection time was about 8 min. During the injection, the spectral changes took place immediately. This means that the stationary concentration of Ag+ ions was low during the injection, which is the reason why practically no spontaneous nucleation of individual Ag, particles occurred. The palladium concentration in the final solution was 2.9 X le5 M, and the total concentration of added silver varied between 2.2 X 10-6 and 2.0 X 10-4 M.

A Pressure-History-Matching Method for Determination of Relative Permeabilities

Summary A pressure-history-matching method for determining relative permeabilities was developed and verified in a one-dimensional (1D), analytical/experimental study. The matching method is based on a pressure history induced by injecting a gas (nitrogen in this study) into an incompressible-fluid-saturated porous medium. The analytical model uses relative permeabilities expressed as two-parameter functions of saturation. A parametric study with a finite-difference implicit pressure, explicit saturation (IMPES) solution of the analytical model showed that the relative permeabilities can be determined by matching pressure histories in three steps: (1) match calculated pressure history with measured pressure history during the initial period of 1% of the total injection time, (2) match calculated pressure history with measured pressure history during the final period of 1 % of the total injection time, and (3) minimize differences between calculated and measured pressure histories at no fewer than three selected intermediate times. The parametric study also showed that determining relative permeabilities with this pressure-history-matching method requires a knowledge of porosity and specific permeability. Experimental verification compared relative permeabilities of a core determined by the pressure-history-matching method with the relative permeabilities measured by the classic transient-displacement method. The comparison showed errors in the relative permeability of ±5% for water flow and +30% for gas flow.

Combined superior vena cavography and azygography in patients with suspected lung carcinoma.

Intraosseous costal or spinous process azygography has occasionally been used for visualization of the thoracic venous system in the preoperative assessment of carcinoma of the lung (2, 7). Obstruction of the superior vena cava or extrinsic compression or invasion of its lumen is a relatively frequent finding in the natural history of pulmonary carcinoma, especially when the lesion originates in the right lung (3). In 85 per cent of 33 cases coming to autopsy in one series, cancer was the etio-logic agent producing superior vena caval obstruction (1). To our knowledge, the combined use of superior vena cavography and azygography as part of the preoperative assessment of pulmonary carcinoma has not been previously reported. Our experience with 63 consecutive patients who have been evaluated for suspected primary lung carcinoma by the use of superior vena cavography and azygography forms the basis of this report. The roentgenographic patterns of abnormality are evaluated and presented. The importance of proper technic is discussed. Assessment of each study separately and in combination is made to determine its value in defining resectability. Materials and Technic Sixty-three patients with suspected primary pulmonary cancer were evaluated by a diagnostic work-up which included pos-tero-anterior and lateral chest roentgenograms, transtracheal bronchography (6), azygography and superior vena cavography, scalene node biopsy, bronchoscopy, sputum cytology, and pulmonary function studies. The clinical records of each patient were reviewed, and the significance of the findings from azygography and superior vena cavography was correlated with the operative and pathological findings. Azygography and superior vena cavography were performed at the same time in all cases. Each patient was premedicated with 50 mg meperidine (Demerol), 100 mg secobarbital (Seconal), and 25 mg Phener-gan thirty minutes before the start of the procedure. A rapid-sequence film-changer should be used for both azygography and superior vena cavography if really meaningful results are to be obtained. False-negative examinations are greatly minimized (Fig.1). False-positive examinations due to spurious physiologic obstruction from the Valsalva maneuver or tightening of neck and shoulder musculature are eliminated by using serial exposures and by cautioning the patient to remain relaxed and to continue breathing normally throughout the injection and exposure times (Fig. 2, A and B). The equipment for superior vena cavography includes two 30 cc syringes, each containing 25 cc of 50 per cent Hypaque and No. 16 gauge needles with plastic connecting tubing. The basilic veins in both antecubital fossae are injected simultaneously by hand to give complete visualization of the innominate veins as well as of the superior vena cava. The total injection time is between two and three seconds.