A previous study preferred a fixed delay time for bolus tracking owing to the lack of consistency in optimal triggering. The standard contrast material used for IV administration is a non-ionic, low-osmolar contrast agent with a concentration between 240 and 400 mg I/ml (most frequently 300 mg I/ml). With our study protocol of a 30-second injection and 10-second saline flush, the optimal temporal window to achieve pulmonary artery enhancement greater than 200 H was from 16 seconds to 41 seconds after the start of the injection. 18g -22g, Location: No lower than 2 below the AC crease of the elbow, pressure approved TLC, PICC lines, (NOTE: For PV IV flush with the arm in the position it will be for the scan), OMNI 350, 1ml/kg Omni 300 @ 1.5-2ml/sec (maximum dose 125mL). This makes it easy to reconstruct 3D volume-rendered images with fusion of the arteries and veins. Federal government websites often end in .gov or .mil. PEG and Volumen have the advantage that there is better bowel distension. the contents by NLM or the National Institutes of Health. Young patients and especially pregnant women have a high cardiac output, which results in dilution of the contrast and poor enhancement. Rodallec MH, Krainik A, Feydy A et-al. Optimal scan timing allowed us to visualize intracranial arteries or veins with minimal superimposition. Exam is ordered as Stereotactic for Surgery Planning. The ability to distinguish between vascular sections from the cerebral sulcus and tubercle was also improved (P<0.01). CT lumbar spine (protocol) | Radiology Reference Article - Radiopaedia.org Dynamic perfusion CT: optimizing the temporal resolution and contrast volume for calculation of perfusion CT parameters in stroke patients. OMNI 350 mixed volume 60ml (80% contrast & 20% saline) with a saline flush. Background and purpose: Contrast-enhanced spiral CT studies of the head and neck are performed frequently using contrast material volumes of approximately 30 g iodine and a scan delay of 30-45 seconds. The purpose of contrast-enhanced CT (CECT) is to find pathology by enhancing the contrast between a lesion and the normal surrounding structures. NB: This article is intended to outline some general principles of protocol design. The marks of contrast phases on all images obtained were erased, then images were analyzed by 2 professional radiologists according to the following scoring method: for the size of isolated lesion, larger at the delayed phase (DP) than the immediate phase (IP): DP scored 2, and IP scored 0; larger at IP than DP: DP scored 0, and IP scored 2, equal on the both phase images: both phases scored 1; for the marginal definitions, more clearly at DP than IP: the DP scored 2, and IP scored 0; more clearly at IP than DP: the DP scored 0, and the IP scored 2; same on the 2 phase images: both phases scored 1; and quantitative analysis of the ability to distinguish the isolated lesion from the vascular section: tightly associated or indistinguishable: scored 1, otherwise (easily distinguishable), scored 2. Orrison WW, Jr, Snyder KV, Hopkins LN, Roach CJ, Ringdahl EN, Nazir R, et al. Purpose The CTA of the cerebral arteries is performed to demonstrate the full patency of the cerebral arteries via contrast enhancement. 5. The site is secure. Lammie GA, Hewlett RH, Schoeman JF, Donald PR. Lell MM, Anders K, Uder M, Klotz E, Ditt H, Vega-Higuera F, et al. Diagnostic Task Detect collections of blood; Identify brain masses; Detect brain edema or ischemia; Identify shift in the normal locations of the brain structures including in the cephalad or caudal directions; Evaluate the location of shunt hardware and the size of the ventricles; On a non enhanced CT-scan (NECT) liver tumors are not visible, because the inherent contrast between tumor tissue and the surrounding liver parenchyma is too low. All patients were received immediate and 5-min delayed head scanning after contrast agent injection. Optimal contrast enhancement is important for a succesful diagnostic CT-scan. The optimal scan delays of the arterial and pancreatic parenchymal phase in multi-phase CT scan using fixed scan delay or bolus-tracking should be determined with consideration of the injection duration. Smit et al21 reported the usefulness of a simultaneous evaluation technique for the arteries and veins with their CT perfusion data. If there was disagreement, a consensus decision was reached through consultation. Finally, 60 subjects (32 females and 28 males; age range, 1786 years; median age, 56 years) were enrolled in this study. In our quantitative and qualitative assessment, the optimal arterial scan timing should be present between 6.0s and 8.0s after Taa. In a future study, an animal cerebral perfusion scan would be carried out, and the time to peak (TTP) of intracranial disease would be studied comprehensively and in detail. Scan range was from the OM line to the parietal lobe of the brain, with a section thickness of 5 mm and a layer spacing of 5 mm. CT Contrast Timing - Radiology Protocols A previous study preferred a fixed delay time for bolus tracking owing to the lack of consistency in optimal triggering.23 In another study of brain CTA at 320-row MDCT, a test bolus was also used for a similar reason.22 However, the combination of our proposed scan timing and detection of the CM arrival at the ICA, confirming the ascent of the ICA attenuation from the baseline, could resolve this defect in 3D-CTA with bolus tracking. This phenomanon is especially seen in younger patients, who are capable of deep inspiration. Brain CT and MRI findings in 100 consecutive patients with intracranial tuberculoma. According to World Health Organization (WHO) data, there were 9 million new cases of tuberculosis (TB) globally in 2007, and China had the worlds second-largest tuberculosis epidemic, with 1.3 million new cases in the same year, accounting for 14% of the overall global incidence [1]. We therefore believe that research for the appropriate CT scanning mode is necessary and has great value in clinical applications. Twenty-seven patients with biopsy-proven squamous cell carcinoma of the head and neck underwent dual-phase helical CT examinations using 100 mL of nonionic contrast material. The present study was conducted to determine the optimal scan timing for arteryvein separation at whole-brain CTA. When we give i.v. Corresponding Author: Xiangxing Ma, e-mail: Received 2014 Mar 19; Accepted 2014 May 15. As a matter of experience, the 5-min delay is usually the proper scanning time. Leakage after bowel surgery is a great clinical problem. Bethesda, MD 20894, Web Policies Murayama K, Katada K, Nakane M, Toyama H, Anno H, Hayakawa M, et al. If there is a closed loop obstruction, this will be more obvious on a CECT. Awai et al17 reported that the time from CM arrival to peak enhancement at the aorta depends on the injection duration. The maximum Dscore in the arterial-dominant phase was observed at 6.0s (Dscore=1.97) followed by the value at 8.0s (Dscore=1.88) after Taa. If 5cc/sec is not possible or not needed because you are only interested in the late portal phase. Detection of intracranial aneurysms: multi-detector row CT angiography compared with DSA. - Delay: 60 sec. Careers, Unable to load your collection due to an error. You do not want to tell the surgeon that there is probably leakage, but you are not sure. 1. Use mAs of 375. AJR 2007; 189:314-322, by Pr Dahlman and Aart J. van der Molen If this scanning mode were used in our routine work, the radiation dose would be greatly reduced. Indications include the diagnosis of cerebral venous thrombosisand preoperative anatomy particularly for posterior fossa surgery where the sigmoid sinuses may be compressed (e.g. Address correspondence to: Mr Takashi Shirasaka. Volume Acquisition for repeats if motion artifacts present. These values were significantly higher than those in other arterial-dominant phases (p<0.001). Good enhancement in SVC and aorta in image 3A, but insufficient enhancement of the pulmonary vessels due to TIC in image 3B. When the blood in the descending aorta reaches a density of 130 hounsfield units, the scanner automatically scans the patient. Example: A CTA Chest ROI is placed in the descending aorta. Nonetheless, a study on the preference of delayed scan in MSCT scanning has never been reported. OHSU is an equal opportunity affirmative action institution. Patient has had a Head WO Contrast within the last 6 hours. With respect to intracranial tuberculoma, regardless of location affected (basal cistern meninges, pia mater, or ependymal), the images obtained from 5-min delayed scan were superior to those obtained from the first phase in terms of both lesion size and margin displaying (P<0.01) (Table 1). The quantitative data acquired was conducted by the normality test method, and was approximately normally distributed (P>0.05), thus the t-test was used. Cerebral CT venography. Include skin surface if possible. Therefore, evaluation was performed within 20.0s after Taa. or at 70 sec p.i. which is comparable to 600 mg I/kg. Measurement of cerebral circulation times using dynamic whole-brain CT-angiography: feasibility and initial experience. At immediate phase scan (B), the lesion showed slight enhancement, while the enhancement was further improved at delayed phase scan (C) because the range of lesion expanded and the boundary was more clearly outlined. Young patients are capable of deeper inspiration, which can lead to transient interruption of contrast. A substantial interrater agreement was observed (=0.613). 1 Routine Head 2 Temporal Bones/IAMs 3 Circle of Willis (COW) CTA 4 Facial Bones/Sinuses 5 Soft Tissue Neck 6 Carotid Arteries CTA Routine Head Temporal Bones/IAMs Circle of Willis (COW) CTA scan routine head post-contrast Facial Bones/Sinuses Soft Tissue Neck Carotid Arteries CTA This page was last edited on 11 November 2020, at 16:42. Rock RB, Olin M, Baker CA, et al. Inclusion in an NLM database does not imply endorsement of, or agreement with, So a hypervascular tumor will be best seen in the late arterial phase. A 320-MDCT scanner has z-axis coverage of 16 cm and can acquire whole-brain volumetric data in 0.5 second.For CT angiographic procedures, the subsecond imaging time can be used to reduce the dose of iodinated contrast medium by scanning at the peak contrast attenuation of the vessel and thereby avoiding prolonged contrast medium administration []. British Infection Society guidelines for the diagnosis and treatment of tuberculosis of the central nervous system in adults and children. Figure 3 shows the images at the time after Taa in the arterial-dominant phase. the contents by NLM or the National Institutes of Health. The CT-image shows nice enhancement of the normal bowel wall (yellow arrows) and no enhancement of the infarcted bowel (red arrows). For distinguishing vascular sections from the cerebral sulcus and the tubercle, the images obtained from 5-min delayed scan had much better performance than these obtained from the immediate phase scan (P<0.01) (Table 2). ), Optimal liver enhancement (metastasis, cysts, abscesses, etc. In these situations, consider using the test bolus technique, With any bolus tracking protocol you can have a monitoring delay and a diagnostic scan delay, Monitoring delay is the delay from injection start to actual tracking of the bolus, Diagnostic scan delay is the delay between crossing the HU threshold and the actual scan initiating, Example: A protocol has a 10 second monitoring delay/80 HU threshold/15 second diagnostic scan delay. In the TDCs, we basically estimated the contrast media arrival time as the observed time ascent of the ICA attenuation from the baseline.19 The contrast media arrival time at the ICA (Taa) and contrast media arrival time at the SSS (Tav), peak enhancement time at the ICA (Tpa) and peak enhancement time at the SSS (Tpv) and interval time at the ICA (Tia) and interval time at the SSS (Tiv) were defined as follows: Ta=2.0s earlier than the acquisition time when CT attenuation exceeded 150HU and Ti=time difference between Ta and Tp (TpTa) (Figure 1). For qualitative analyses, two board-certified neuroradiologists (AH and KY with 17 and 13 years' experience) independently evaluated the depiction of the major intracranial arteries and veins on the contralateral side without a mass lesion. The upper images are of a patient with liver cirrhosis and multifocal hepatocellular carcinoma examined after contrast injection at 2.5ml/sec. For late arterial phase imaging 35 sec is the optimal time, so you start at about 25 seconds and end at about 45 seconds. The Cohen's kappa test was used to assess the degree of agreement between the observers, with a kappa value of 0.010.20 for slight agreement, 0.210.40 for fair, 0.410.60 for moderate, 0.610.80 for substantial and 0.811.00 for almost perfect agreement. Ttra was 5.71.4s. The arterial-dominant phase continued until 12.0s, and the venous-dominant phase extended from 12.0 to 20.0s after Taa. Whole-brain perfusion CT performed with a prototype 256-detector row CT system: initial experience, Effect of contrast material injection duration and rate on aortic peak time and peak enhancement at dynamic CT involving injection protocol with dose tailored to patient weight. Smit EJ, Vonken EJ, van der Schaaf IC, Mendrik AM, Dankbaar JW, Horsch AD, et al. May not scan at the right time due to the trigger HU never being reached from factors such as cardiac output, body habitus, etc. Volume Acquisition for repeats if Motion Artifacts are present. Before Cherian A, Thomas SV. NA 60 sec Non-helical 16 x 1.5 mm OR helical 64 x 1.2 mm, 32 x 1.2 mm (128 slice) 4.5 mm OR (helical) 5 mm thick axial reformats, and post-contrast coronal reformats H30s kernel (axials) Rectal contrast is given in cases of suspected bowel perforation or anastomosis leakage. Use for instance a green venflon. With regard to the arteries, 60 (100%) of the 60 patients had a mean score of >2 at 8.0s and 10.0s after Taa. Thin data set must be at 512 matrix with a maximum image count of 690 (or less) to load into the Super D system. Casey SO, Alberico RA, Patel M et-al. Based on our clinical experience, immediate MSCT scanning after contrast agent injection was unable to demonstrate the changes of intracranial TB lesions in morphology and density. A NECT without any oral or rectal contrast is needed to compare with the CECT with rectal contrast, because you don't want to end up in a discussion whether some hyperdense stuff outside the bowel is leakage or some post-operative material, dense bowel content or contrast from an earlier examination. Sixty-four-row multisection CT angiography for detection and evaluation of ruptured intracranial aneurysms: interobserver and intertechnique reproducibility. Intravenous Contrast Medium Administration and Scan Timing at CT Once the HU crosses 80HU, the scanner counts down 15 seconds before the scan is acquired. Alberico RA, Patel M, Casey S, Jacobs B, Maguire W, Decker R. Evaluation of the circle of Willis with three-dimensional CT angiography in patients with suspected intracranial aneurysms. However, there was no quantitative evaluation of the degree of venous contamination relating to the Datt. The difference between the mean score for the intracranial arteries and the mean score for the veins (Dscore) was calculated for each phase: Dscore=mean score for the intracranial arteriesmean score for the intracranial veins. The aim of this study was to determine whether the diagnosis of intracranial tuberculosis (TB) can be improved when multi-slice computed tomography (MSCT) scans are taken with a 5-min delay after contrast media application. Contrast-Enhanced Helical CT of the Head and Neck: CT cerebral venography (also known as a CTV head or CT venogram ) is a contrast-enhanced examination with an acquisition delay providing an accurate detailed depiction of the cerebral venous system. We ask the patient to breath in normally and hold his breath to avoid the transient interruption of contrast, which will be explained in a moment. We have reviewed contrast medium pharmacokinetics and patient, contrast medium, and CT scanning factors associated with contrast enhancement and scan timing and discussed clinical considerations and modifications in protocols required to optimize contrast enhancement for common clinical CT applications. HU, Hounsfield unit. Whole-brain 4D-CTA examinations were performed using a 320-row MDCT volume scanner (Aquilion ONE Vision Edition; Toshiba Medical Systems Corporation, Otawara, Japan). Therefore, we could scan the arterial phase in the time period between 6.0s and 8.0s from Taa. There were 20 meningiomas, 11 gliomas, 9 schwannomas, 7 lymphomas, 5 pituitary adenomas, 4 metastatic tumours, 1 haemangioblastoma, 1 epidermoid tumour, 1 cavernous malformation and 1 demyelinating disease. The optimal scan timing to achieve good arteryvein separation at whole-brain CTA using 320-row MDCT with a CM injection duration of 10.0s was found to be 6.0s or 8.0s for the arteries and 16.0s for the veins after CM arrival at the ICA. Optimal scan timing for artery-vein separation at whole-brain CT A hypovascular liver tumor however will enhance poorly in the late arterial phase, because it is hypovascular and the surrounding liver does also enhance poorly in that phase. In some cases it can be difficult to differentiate a pancreatic carcinoma from a focal chronic pancreatitis. The number of patients with mean scores of >2 for the arteries and veins was also evaluated. 6. Seo H, Choi DS, Shin HS et-al. CT Protocols | OHSU For arteryvein separation, a period of at least Ttra, the cerebral circulation time, is required between the arterial phase and the venous phase. CT Protocols - Head, Face, & Neck - wikiRadiography 150cc contrast at 5cc/sec. Indirect CT venography of the lower extremities: impact of scan delay They are based on a 64-slice scanner but can be used for any CT-scanner independent of manufacturer. Bethesda, MD 20894, Web Policies Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. When you know in advance, that you are dealing with hypovascular metastases, a hepathic phase at 70 sec p.i. CT Perfusion of the Head - RadiologyInfo.org Check for errors and try again. There were no statistically significant differences in Datt (p=0.375) or Dscore (p=0.139) between these scan timings. Contrast: - Contrast Type: Per site. Tuberculous encephalitis, tuberculous vasculitis, and tuberculous brain abscess were excluded from the present study. A graph showing the scanning protocol for whole-brain four-dimensional CT angiography: the scanning speed was 1.0s per rotation. The contrast agent iohexol (350 mg/mL) was injected intravenously with a dose of 1.2 ml/kg (patient body weight) and a speed of 2.5 ml/sec. The table shows an overview of some of the CT-protocols, that we use (click to enlarge). CT examination of the pancreas should always be done with maximum amount of contrast at a maximum flow rate, because both small pancreatic carcinomas aswell as pancreatic necrosis in pancreatitis are difficult to detect. Image acquisition with 5-min delay after contrast agent injection should be performed as a standard scanning protocol to diagnose intracranial TB. Image of the immediate phase scan (B) showed detectable enhancement of the affected meninges, but was hardly distinguished from the peripheral vasculature due to poor display. In the arterial-dominant phase, attenuation of the vein begins to rise after around 6.0s from Taa. Our study shows that delayed acquisition at 5-min after contrast agent injection can improve precision and accuracy for imaging evaluation and clinical diagnosis, and be the preferred scanning type. The coronal reconstruction nicely shows bowel wall enhancement in a patient with ileus due to a small bowel obstruction. 2. Figure 2 shows the mean TDCs of the ICA and SSS after Taa. The hounsfield units of a chosen region of interest (ROI) is monitored during the contrast bolus injection. Images obtained with 5-min delayed scan time were superior in terms of lesion size and meningeal thickening outlining in all disease types (P<0.01). In a total of 51 subjects, 27 patients with cerebrovascular disease, 8 patients with multiple metastatic tumours, 10 patients with post-operative status and 6 patients with severe motion artefacts during scanning were excluded owing to the exclusion criteria. In the late arterial phase at 35 sec hypervascular lesions like HCC, FNH, adenoma and hemangioma wil enhance optimally, while the normal parenchyma shows only minimal enhancement. Early brain CT can help diagnose TB and provides important baseline information, particularly when considering surgical interventions for hydrocephalus [3]. We enrolled 30 patients, including 19 males and 11 females, ages 1058 years (mean age=29.3 years) who were clinically diagnosed with intracranial TB between January 2008 and November 2011. This is a closed loop obstruction with strangulation. 2006;187 (6): 1637-43. At delayed phase scan (C), the enhancement of blood vessel receded and the lesions become more obvious. Bone subtraction 3D CT venography for the evaluation of cerebral veins and venous sinuses: imaging techniques, normal variations, and pathologic findings. Dynamic Expiration for Peds breathe out and hold it out. and only a little bit in the late arterial phase at 35-40 sec p.i.. All liver tumors however get 100% of their blood supply from the hepatic artery. Results: The CE increased with increasing scan delay and reached a plateau from 120 to 210 s. The percentages of examinations achieving enhancement above . Tamura Y, Utsunomiya D, Sakamoto T, Hirai T, Nishiharu T, Urata J, et al. Notes: - Noncontrast for trauma, contrast for infection or mass. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License, Medicare Part C, Tomography, Spiral Computed, Tuberculosis, Central Nervous System. The present study suffers from a number of limitations. This figure is to summarize the enhancement patterns. 1Department of Medical Technology, Division of Radiology, Kyushu University Hospital, Fukuoka, Japan, 2Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 3Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. PDF Adult Head CT - AAPM: The American Association of Physicists in Medicine PRACTICE PARAME TER 1 CT Head The American College of Radiology, with more than 30,000 members, is the principal organization of radiologists, radiation on cologists, and clinical medical . Position patient's head as straight as possible. Developmental delay [29,59] 4. In this study, we investigated the optimal scan timing for the case of bolus tracking. Ertl-Wagner BB, Hoffmann RT, Bruning R, Herrmann K, Snyder B, Blume JD, et al. A 320-row multidetector CT (MDCT) is expected for a good arteryvein separation in terms of temporal resolution. To solve this problem, dual-phase MSCT scanning was done in a group of patients with intracranial TB to discover the optimal scan timing window for displaying intracranial TB. PRACTICE PARAME TER 4 CT Head C. Contrast Studies . By Carole A. Ridge et al. Comparison on image qualities of various types of lesions between delayed phase and immediate phase scans. 2014;202 (2): W169-75. 2004;25 (5): 787-91. If you want to characterize a liver lesion, you need maximum contrast at a maximum flow rate, i.e. For instance, a non-gated flash aorta will move into scan position and acquire much quicker than a gated flash aorta due to the heart rate synchronization of gated protocols. Siebert E, Diekmann S, Masuhr F, Bauknecht HC, Schreiber S, Klingebiel R, et al. Unable to process the form. First, we analyzed 4D-CTA data scanned with a tube voltage of 80kVp. Diversity, Equity, Inclusion and Belonging Committee, Creatinine Testing Prior to Injecting Intravenous Iodinated Contrast Media, Iodinated Contrast Administration in Patients Receiving Metformin, Guidelines for Periprocedural Coagulation Management, Stereotactic/synthes head without contrast, Office of Civil Rights Investigations and Compliance, 2ml/kg OMNI 300 @ 1.0-4.0ml/sec. Volume Acquisition for repeats if Motion Artifacts are present. Sometimes a lesion will be hypovascular compared to the normal tissue and in some cases a lesion will be hypervascular to the surrounding tissue in a certain phase of enhancement. For quantitative analyses, we investigated the time when the maximum difference in CT attenuation between the intracranial arteries and veins was observed. A ROI is placed in the pulmonary trunk. At pre-contrast CT scan (A), partial obstruction of cisterna ambiens was revealed. Granulation tissue was the pathological basis of the meningitis-related meningeal thickening, regardless of which portion of meninges (basal cistern meninges, pia mater or ependymal) was affected. Pozzi-Mucelli F, Bruni S, Doddi M, Calgaro A, Braini M, Cova M. Detection of intracranial aneurysms with 64 channel multidetector row computed tomography: comparison with digital subtraction angiography. MSCT of the head was performed using a GE LightSpeed 16-Slice CT scanner (MSF Medical Equipment & Service LTD., Lightspeed). Certain indications require . After contrast enhancement, the vascular sulcus sections were highly enhanced at the immediate phase and were difficult to differentiate from the tubercle due to its smaller diameter. Central nervous system tuberculosis: pathogenesis and clinical aspects. The CT-images show an early arterial phase in comparison to a late arterial phase. For Late portal venous phase imaging it is different. At immediate phase scan (B), thickening of left parietal lobe pia was seen, with significant enhancement. government site. For monitoring the CM arrival at the circle of Willis for 3D-CTA using bolus tracking, we investigated the time from CM arrival at the internal carotid artery (ICA). If this patient would have been given positive oral contrast, you probably would not have notice the ischemic bowel. A diagnostic delay is good for venogram type protocols where you still want a tight bolus (4-5ml/s) but you have a long delay for the venous system, 90-120s before the scan is actually acquired. The technique was considered as a revolutionary advance in medical imaging, especially in high quality CT angiography [9]. Matsumoto et al10 reported a technique for obtaining a separate demonstration of the arterial and venous phases on brain three-dimensional (3D)-CTA at 16-row multidetector CT (MDCT). Youssef FG, Afifi SA, Azab AM, et al. The explanation is the following: Thick MIP reconstructions can be helpful in following the vessels and detecting emboli. For a pulmonary embolism CT, an ROI is placed in the pulmonary artery and a test bolus is given. The ordering Provider or Radiologist does not want it. Timing of CT-series is important in order to grab the right moment of maximal contrast differences between a lesion and the normal parenchyma.
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